Harding et al (2009a)

Automated Scoring For Elite Half-Pipe Snowboard Competition – Important Sporting Development Or Techno Distraction?

JASON WILLIAM HARDING1, 2, 3, COLIN GORDON MACKINTOSH4, DAVID THOMAS MARTIN1, ALLAN GEOFFREY HAHN5, DANIEL ARTHUR JAMES3, 6 

  1. Department of Physiology, Australian Institute of Sport, Canberra, Australian Capital Territory, Australia
  2. Olympic Winter Institute of Australia, Melbourne, Australia
  3. Centre for Wireless Monitoring and Applications, Griffith University, Brisbane, Australia
  4. Applied Sensors Unit, Australian Institute of Sport, Canberra, Australia
  5. Applied Research Centre, Australian Institute of Sport, Canberra, Australia
  6. Centre of Excellence for Applied Sport Science Research, Queensland Academy of Sport, Brisbane, Australia

* Correspondence to: Department of Physiology, Australian Institute of Sport, PO BOX 176 Belconnen ACT 2616, AUSTRALIA

E-mail: Jason.Harding@ausport.gov.au

ABSTRACT:  The authors have previously reported a strong relationship between video based objective data (air-time and degree of rotation) and subjectively judged scores awarded during elite half-pipe snowboard competition.  Advancements in sports monitoring technologies now provide the capacity to accurately and automatically quantify this objective information. This may assist current subjective coaching and competition judging protocols provided the integration process imparts a large element of control to key players within the sport.  The authors therefore recently hosted an invitational half-pipe snowboard competition (2007 Australian Institute of Sport (AIS) Micro-Tech Pipe Challenge) designed to evaluate whether the snowboard community would embrace a competition where results were in part determined by automated objectivity, explore the practical, logistical and technical challenges associated with conducting such an event and evaluate the relationship between subjective judging and results predicted from objective information to see if prior research had ecological validity.  Ten elite male half-pipe snowboarders were instrumented with inertial sensors throughout this competition.  A prediction equation using previously established weightings of average air-time and average degree of rotation accounted for 74% of the shared variance in subjectively judged scores awarded during this competition.  Although our predictions of overall scores and rankings were good there was still 26% of the total variance unexplained.  This should not be considered a weakness of this approach but a strength as the subjective components of style and execution should never be removed from the sport.  The future of half-pipe snowboarding however may be best guided a judging protocol that incorporates both objective and subjective criteria.

KEY WORDS: Half-pipe Snowboarding, Technology, Judging, Accelerometers, Rate Gyroscopes, Objectivity, Subjectivity.

1- INTRODUCTION

1.1 – Overview

The snowboarding practice community perceives air-time and degree of rotation as important components in successful half-pipe riding however athletic training progression and competition performances are currently assessed by purely subjective measures.  We have previously provided quantitative evidence of the effect air-time and degree of rotation has on competition performance that supports this practice community perception.  Furthermore both of these objective performance variables can now be calculated and classified using basic signal processing of inertial sensor data.  Such sport specific automated objectivity is theorised to enhance training and competition performance assessment protocols however it is imperative that key members within the sport be part of any integration process.  We have recently conducted an invitational half-pipe snowboard competition in collaboration with the practice community that required athletes to compete whilst wearing inertial sensors.  The main purpose was to evaluate the utility of micro-technology to enhance current subjective judging protocols and to compare scores predicted from purely objective data to subjectively established scores and rankings made by an expert judge.  In addition we hosted a special event where the overall rankings were established entirely based on inertial sensor data to gauge the acceptance of this objective evaluation technique within the sport of half-pipe snowboarding.    

1.2 – Elite-Level Half-Pipe Snowboarding

Snowboarding was originally a counter-culture recreational activity derived from surfing and skateboarding.  Antagonistic to the accepted use of alpine ski resorts around the time of the sporting discipline’s inception, snowboarding was initially banned in most ski resorts.  Snowboarding has subsequently been somewhat partitioned from the skiing fraternity ever since.  The sport however has been a part of the Winter Olympic competition program since the 2002 Winter Olympic Games.  Snowboard half-pipe courses are shaped like a long half cylinder and are usually created from large amounts of snow that is shaped into the preferred profile using specially designed snow groomers.  Although the dimensions vary within different ski resorts, Federation International de Ski (FIS) World Cup and Winter Olympic snowboard half-pipes are commonly 160 – 200m long, 18m wide, are situated on transitions of approximately 18 degrees and have wall transitions of 5 – 6m.  Recent developments within the sport however have seen the introduction of grooming machines capable of creating wall transitions of 7 – 8m (Figure 1).  Half-pipe snowboarding is a sporting discipline where athletes are required to perform an aerial acrobatic routine on a half-pipe snowboard course made of snow.  The aerial acrobatic routines performed by half-pipe snowboard competitors are currently judged in competition by a purely subjective measure termed overall impression.  This performance assessment measure takes into account a large number of sport specific components such as the amplitude, degree of rotation, difficulty, style and execution associated with each aerial acrobatic manoeuvre, the sequence and combination of aerial acrobatic manoeuvres, the amount of risk in the routine, the overall use of the half-pipe including the line taken through the course and how the run progresses and flows.  Half-pipe snowboarding has until recently received very little attention from scientists and the subsequent focus on objectifying sport specific parameters to enhance athletic performance and assist elite-level judging protocols. 

calgary-olympic-park-edited1

Figure 1. A current Olympic Standard snowboard half-pipe in Calgary Olympic Park. This half-pipe has been shaped by the new "22ft Zaugg Pipe Cutter" (generating wall transitions of approximately 7 - 8m) and will most likely be the size and shape of the half-pipe course that will be used in the 2010 Winter Olympics in Vancouver. Image: Ben Alexander 2008.

1.3 – Automated Objectivity – Air-Time

There is evidence from coaches, judges and spectators that suggests that air-time (Figure 2) and amplitude are crucial components of half-pipe snowboarding competitive success [1, 2].  The components of air-time and amplitude however, are currently assessed subjectively by elite-level coaches and competition judges when providing performance feedback to athletes.  The authors have previously shown that air-time can be objectively calculated using video based analysis and that there is a significant and large linear relationship (r = 0.56 ± 0.26, p value < 0.001, r2 = 0.31, SEE = 4.60, n = 30) between total air-time and an athletes subjectively judged score during two FIS World Cup half-pipe snowboarding competition finals held in Bardonecchia Italy 2005 [3].  It is believed however that the use of video analysis to objectively calculate information on air-time during half-pipe snowboarding would be difficult to incorporate on a routine basis.  This is a result of the labour intensive nature of manual post-processing of video data and the subsequent time delay in information feedback.  The authors have therefore promoted the use of micro-technology to provide automated objective feedback on air-time and have recently shown that air-time can be accurately and reliably calculated using inertial sensor output (provided by tri-axial accelerometers) and basic signal processing techniques [3].  This particular study showed there was a very large correlation (r = 0.78 ± 0.08; p value < 0.0001; r2 = 0.61, SEE = 0.08; n = 92) between a criterion measure (video based analysis) and novel technology-based (accelerometer signal processing technique) methods.  Approximately 95% (94.57%) of the accelerometer measures lie within ± 0.15s of the criterion measure. The two pass signal processing technique promoted within this study was able to detect 100 percent of the aerial acrobatic manoeuvres performed [3].  The capacity of micro-technology and basic signal processing techniques to accurately and reliably calculate air-time for 100 percent of aerial acrobatic manoeuvres is theorised to allow successful integration of this concept into half-pipe snowboarding training and competition judging environments.

jarryd-air-time

Figure 2. Australian athlete performing an aerial acrobatic manoeuvre focussed purely on maximising air-time whilst ensuring the subjective components of good style and execution are not lost in the process. Photo captured during a routine national team training session at Persiher Blue Ski Resort. Image: Heidi Barbay © www.AnarchistAthlete.com 2007

1.4 – Automated Objectivity – Degree Of Rotation

Air-time is only one component of successful half-pipe snowboarding performance.  The aerial acrobatics and the associated degree of rotation associated with those acrobatics (Figure 3) also contribute to a competitor’s overall score.  As is the case with air-time, there is evidence that promotes the degree of rotation associated with each aerial acrobatic manoeuvre as an important component in successful half-pipe snowboarding [1, 2].  The authors have recently shown that there is a strong relationship (r = 0.55 ± 0.26, p value = 0.002, r2 = 0.30, SEE = 4.63, n = 30) between total degree of rotation alone and overall competition score during two World Cup finals in Bardonecchia Italy 2005 [4].  It is believed that for a given air-time, an athlete that accumulates more degree of rotation will score better in competition, provided the aerial acrobatic manoeuvres have been executed well.  Similar to the case with air-time, there is reason to believe that automatic calculation of degree of rotation may prove beneficial in assisting elite-level coaching and competition judging protocols by allowing the individuals in charge of assessing performance to focus on the more stylistic components of the sport.  The authors have recently shown that it is possible to automatically and reliably classify aerial acrobatics into sport specific rotational groups by processing rate gyroscope data using integration by summation to provide a composite rotational parameter termed Air Angle (AA) [4].  Provided rotations are performed predominantly around a single horizontal axis, the signal processing method provides reliable classification of aerial acrobatics. Mean differences in AA measurement between preceding rotational groups (for example between 360 and 180, 540 and 360, 720 and 540) were statistically significant (mean difference ± SEM = 180.67 ± 21.36, 189.86 ± 22.62, 176.74 ± 11.64; P = 0.004, 0.002, <0.001 respectively). Of the utmost importance however, was the absence overlapping AA measurement limits between different rotational groups. The absence of overlapping AA measurement limits affords some flexibility outside the statistically derived likelihoods whilst still ensuring reliable classification of aerial acrobatics [4].  Although the experienced snowboard community are trained to recognise rotational aerial acrobatics, there is potential for automated acrobatic classification to provide continual performance assessment focussed on degree of rotation (albeit a purely objective assessment) without constant human attention. Coaches, judges and support staff may thereby focus their attention on the more subjective aspects of performance.

mates-rotation-ii

Figure 3. Australian athlete performing an aerial acrobatic manoeuvre focussed on achieving a high degree of rotation whilst again, ensuring air-time, amplitude and the subjective components of good style and execution are not lost in the process. Photo captured during a routine national team training session at Perisher Blue Ski Resort. Image: Heidi Barbay © www.AnarchistAthlete.com 2007

  1.5 – Sociological Perception Toward Automated Objectivity

The key performance variables associated with air-time and degrees of rotation are major components of successful half-pipe snowboarding competition performance.  It is however important to note that the shared variance of subjectively judged scores each objective variable explains seems to be dynamic and subsequently shifts according to a number of different factors; i.e. athletic ability of competitors, environmental and snow conditions and half-pipe course shape and size.  There is evidence however that shows that air-time and degree of rotation are always strongly and positively associated with subjectively judged scores.  Furthermore these variables can now be assessed objectively by either video based analysis or by utilising the recent developments with micro-technology and basic signal processing techniques.  This objective assessment is theorised to provide coaches and competition judges access to performance feedback that until this point has been unavailable.  There is however a potential issue associated with the integration of this concept.  The most significant aspect of technological change in sport is that any integration can dictate the future of a sport in a way that makes reversing such changes very difficult [5].  Technology can additionally have unintended negative consequences with the potential to effect change beyond its original purpose [6, 5].  Half-pipe snowboarding is a sporting discipline that has assessed athletic performance with subjective measures since its inception and currently prides itself on the provision of a competitive platform allowing individuality and athletic freedom of expression. It is believed that for any integration of automated objectivity to be successful within half-pipe snowboarding, a large component of control needs to be designated to key players within the sporting community (Figure 4).  Although there is an awareness that the focus on subjective perception of style and execution in the current competition judging system has an inability to consistently identify correct competition results there is also a strong and somewhat paradoxical community perception that this performance assessment focus is a major strength [1].  There is therefore a dominant negative perception of a proposed automated judging concept based solely on objective information unless the system integrates with the current subjective judging protocol and continues to allow athletic freedom of expression and the capacity for athletes to showcase individual style and flair in elite competition. Athletes, coaches and judges are not totally opposed to the idea however there is a strong practice community perception that further development and integration of this concept be conducted in close association with core community members and be controlled from within the sport (Figure 4).

practice-community

Figure 4. Australian athletes relaxing prior to the start of the AIS Micro-Tech Pipe Challenge. It is imperative that sport scientists considering integrating any form of automated objectivity into elite-level snowboarding work alongside the practice community and allow key community members such as athletes, coaches, judges and the supporting industry to play a major role in the overall direction. Image: Heidi Barbay © www.AnarchistAthlete.com 2007

1.6 – AIS Micro-Tech Pipe Challenge

The 2007 AIS Micro-Tech Pipe Challenge (Figure 5) was the culmination of evaluations focussed on the importance of air-time and degree of rotation in half-pipe snowboard competition scores, the recent capacity to automatically calculate objective information on air-time and degree of rotation using micro-technology and a continual observation of the practice community’s coveted future directions.  The 2007 AIS Micro-Tech Pipe Challenge was an elite-level Australian invitational half-pipe snowboarding competition that utilised both traditional subjective judging measures and innovative micro-technology developed at the Australian Institute of Sport (AIS), Griffith University’s (GU) Centre for Wireless Monitoring and Applications and Catapult Innovations to assess half-pipe snowboarding performance. The event, conducted on July 30th 2007, is believed to be the first half-pipe snowboarding competition in Australia to utilise micro-technology based objective feedback to award athletic performance. The 2007 AIS Micro-Tech Pipe Challenge was primarily a concept event designed to evaluate whether the snowboard community would embrace a competition where results were in part determined by automated objectivity, explore the practical, logistical and technical challenges associated with conducting such and event and evaluate the relationship between subjective judging and results predicted from objective information to see if prior research had ecological validity.   This paper is focussed primarily on the ecological validity of prior research and evaluates the relationship between subjectively judged scores and results predicted from objective information using previously established weightings.

ai-31658-ais-micro-tech-pipe-jam-flier_1

 

 

 

 

Figure 5. AIS Micro-Tech Pipe Challenge 2007 Competition Flier.

2-EXPERIMENTAL

2.1 – Subjects

Ten elite-level male Australian half-pipe snowboarders were recruited and ultimately volunteered to participate in this study. Data collection was performed during the southern hemisphere winter season of 2007 on Monday 30th July at Perisher Blue Ski Resort (altitude 1720 m) on the resort’s custom snowboard half-pipe (length 80 m, width 18 m, transition height 5 m, gradient approximately 15 degrees). Data collection was performed during a total of 50 competition runs. Experimental procedures were approved by the Ethics Committee of the Australian Institute of Sport on 18th August 2005 (ref: 20050808) and in accordance with Griffith University requirements, cleared under special review in January 2008 (ref : PES/01/08/HREC).

2.2 – Equipment And Signal Processing

Implementation of previously developed sensors [7, 8, 9] comprising of one tri-axial accelerometer (100Hz, ± 6g) and one tri-axial rate gyroscope (100Hz ± 1200 deg s-1, 20.94 rad s-1) were used throughout data collection and the associated competition.  Sensors were attached to the lower back of each athlete, situated approximately 5cm to the left of the spine as previously described [3] and as shown in Figure 6.  Raw data was stored on board the sensor unit (256MB Trans Flash) for the duration of data collection process, sampled and analysed post collection by a computer software suite developed in house [8].  Accelerometer components underwent 2-point static calibration in three orthogonal axes (up/down, forward/back and left/right) aligning each axes of sensitivity with and against the direction of gravity. Rate gyroscope components underwent a 2-point calibration integrating angular velocity over time throughout 0 and 90 degrees in three orthogonal axes (yaw, pitch, roll) prior to each data collection session [8, 10].  Panning video footage of each half-pipe run was collected using a Sony 3CCD 50Hz digital video camera from the bottom and centre of the half-pipe to provide feedback on style and execution to athletes and to serve as a back up method of key performance variable calculation in the advent of failure of any of the sensors.

Data was processed with previously documented methods of automated air-time calculation [3] and degree of rotation classification [4] in order to objectively assess these sport specific key performance variables during an elite-level competition environment.  We have previously shown [3] that basic signal processing techniques can calculate air-times associated with individual aerial acrobatic manoeuvres.  The air-time specific signal processing technique is a two-pass method to detect locations of half-pipe snowboard runs using power density in the frequency domain and a subsequent threshold based search algorithm in the time domain which is focussed on the detection of when a snowboarder leaves the snow surface on take off and contact the snow surface upon landing during half-pipe snowboarding.  This technique correctly identified the air-times of 100 percent of aerial acrobatic manoeuvres within each half-pipe snowboarding run (n = 92 aerial acrobatic manoeuvres from 4 subjects) and displayed a very strong correlation with a video based reference standard for air-time calculation (r = 0.78 ± 0.08; p value < 0.0001; SEE = 0.08 ×/÷ 1.16; mean bias = -0.03 ± 0.02s) (value ± or ×/÷ 95% CL) [3]. 

We have also previously shown [4] that basic signal processing of inertial sensor data can classify aerial acrobatic manoeuvres into four sport specific rotational groups (aerial acrobatics with 180, 360, 540 or 720 degree rotations). Classification of aerial acrobatics is achieved using integration by summation. Angular velocity (ω i, j, k) quantified by tri-axial rate gyroscopes was integrated over time (t = 0.01s) to provide angular displacements (θi, j, k). Absolute angular displacements for each orthogonal axes (i, j, k) were then accumulated over the duration of an aerial acrobatic manoeuvre to provide the total angular displacement achieved in each axis over that time period. The total angular displacements associated with each orthogonal axes were then summed to calculate a composite rotational parameter called Air Angle (AA). We observed a statistically significant difference between AA across four half-pipe snowboarding acrobatic groups which involved increasing levels of rotational complexity (P = 0.000, n = 216) [4]. 

Sensors were switched on (Figure 6) and began collecting data at the beginning of the competition (8.30am) and were switched off and ceased data collection immediately after the competitions’ completion (11.00am).  All objective data derived from micro-technology sensors was processed immediately following the competition and required approximately 2-hours to generate a complete assessment of all objective information related to air-time and degree of rotation.

sensor-placement

Figure 6. Australian athlete preparing for the AIS Micro-Tech Pipe Challenge whilst an inertial sensor unit is switched on by a project collaborator from Griffith University's Centre for Wireless Monitoring and Applications Department. The inertial sensor unit was mounted inside a small padded carry bag and positioned on the lower back to the left of the spine. Image: Heidi Barbay © www.AnarchistAthlete.com 2007.

2.3 – Air-Time And Degree Of Rotation Definitions

This paper is focussed upon the utilisation and promotion of objectivity in assessing half-pipe snowboarding performance.  As such the key performance variables of air-time (Figure 2) and degree of rotation (Figure 3) and their associated sub-components require definition for repeatable and reliable measurement.  Air-time begins the first moment there is no longer contact between the snowboard and the snow and ends the moment any part of the snowboard comes in contact with the snow following an attempted aerial acrobatic manoeuvre. It is also believed there are additional variations in aerial acrobatic air-time that have practical relevance to half-pipe snowboarding performance and will allow enhanced training and judging protocols.  These variations also require definition to allow accurate and reliable assessment. 

- Air-time (AT) is measured in seconds and reflects the amount of time the athlete spends in the air during a half-pipe snowboarding aerial acrobatic manoeuvre, beginning the first moment there is no longer contact between the snowboard and the snow and ending the moment any part of the snowboard comes in contact with the snow following an attempted aerial acrobatic manoeuvre.

- Total air-time (TAT) is measured in seconds and calculated by adding together all recorded air-times (typically 6 – 8) during a half-pipe snowboard run [3].

- Average air-time (AAT) is also measured in seconds and is calculated by dividing total air-time (TAT) by number of by the total number of aerial acrobatic manoeuvres completed throughout the duration of a half-pipe snowboarding run [3]. 

- Highest individual air-time (HIAT) is measured in seconds and is the individual aerial acrobatic manoeuvre performed throughout a half-pipe snowboard run that achieves the largest air-time [3].  

Rotation terminology used by half-pipe snowboarding practice communities is not based upon assessment of exact degree of rotation achieved. It is based upon a sport specific approximation that has been previously described [4].  The take-off and more specifically the landing angles (similar but opposite to the take-off angle) associated with half-pipe snowboarding aerial acrobatics generate a situation where exact degree of rotation achieved will always be less than the terminology used to describe it. Theoretically, the degree of rotation achieved during rotations performed predominantly around a single axis is at least, 90 degrees less than the rotation the athlete is credited with based on conventional terminology. Rotational terminology can be based upon the following rules; an athlete will land aerial acrobatics travelling in the same direction they were initiated with in 180 (straight air), 540, 900 and 1260 degree rotations. In contrast an athlete will land travelling in the opposite direction of the initiation during 360, 720 and 1080 degree rotations. These rules apply only in half-pipe and quarter-pipe snowboarding (resultant of the take-off and landing occurring on the same lip). Although snowboarders can ride forwards or backwards, these rules apply regardless of the direction of travel when aerials are initiated [4].  As with air-time, it is believed the key performance variable of degree of rotation should be defined in order for sport scientists to accurately and reliably calculate degree of rotation.  Degree of rotation begins the first moment there is no longer contact between the snowboard and the snow and ends the moment any part of the snowboard comes in contact with the snow following an attempted aerial acrobatic manoeuvre. There are subcomponents of aerial acrobatic degree of rotation that have practical relevance to half-pipe snowboarding performance and will allow enhanced training and judging protocols.  These variations therefore require definition to allow accurate and reliable assessment. 

- Degree of rotation (DR) is measured in degrees and reflects the amount of rotations (calculated using the rules [4] associated with the sport specific approximations) an athlete completes during individual aerial acrobatic manoeuvres performed during a half-pipe snowboarding routine. Note: aerial acrobatic manoeuvres that contain no sport specific rotational component (‘straight airs’) still generate a degree of rotation value of 180 degrees by micro-technology and signal processing and should also be deemed a 180 degree rotation when using video based analysis.  This is because the athlete takes off and lands on the same half-pipe lip and therefore turns through approximately 180 degrees in the horizontal plane.  The first aerial acrobatic manoeuvre with a sport specific rotational component is a 360 degree rotation [4].

- Total degree of rotation (TDR) is measured in degrees and calculated by adding together all recorded rotations associated with each aerial acrobatic manoeuvre performed (typically 6 – 8) during a half-pipe snowboard run.

- Average degree of rotation (ADR) is also measured in degrees and is calculated by dividing total degree of rotation (TDR) by the total number of aerial acrobatic manoeuvres completed throughout the duration of a half-pipe snowboarding run. 

- Highest individual degree of rotation (HIDR) is measured in degrees and is the individual aerial acrobatic manoeuvre performed throughout a half-pipe snowboard run that achieves the largest degree of rotation. 

- Highest cumulative degree of rotation (HCDR) is measured in degrees and is calculated by adding together the total degree of rotation associated with the largest consecutive series of rotational aerial acrobatic manoeuvres.  For example this parameter is associated with the total degree of rotation associated with aerial acrobatic manoeuvres that contain a rotational component that are performed ‘back to back’ or in a consecutive ‘group’. Athletes can perform a string or cluster of consecutive aerial acrobatic manoeuvres that all possess a rotational component during a half-pipe snowboard run.  Strings of consecutive rotational manoeuvres can however be interspaced with what is termed a straight air or a number of straight airs (aerial acrobatic manoeuvres that contain no rotational component) generating a half-pipe snowboard run containing a number of different clusters of ‘back to back’ rotational acrobatic manoeuvres.  There is evidence [1, 2] that athletes who string together a consecutive series of aerial acrobatics with a high rotational component score highly in competition as sequences of consecutive rotational acrobatics increase the difficulty and risk associated with the routine.  The Highest Cumulative Degree of Rotation is focussed on the series of consecutively performed rotational manoeuvres that obtains the highest total degree of rotation throughout a half-pipe snowboard run.  This is different to total degree of rotation which simply adds together the degree of rotation associated with all aerial acrobatic manoeuvres that have a rotational component performed within a completed half-pipe snowboard run, regardless of whether or not those rotational manoeuvres were performed consecutively or ‘back to back’.

2.4 – Competition Format and Judging

The purpose of this competition was to compare traditional subjective judging results with those predicted using purely objective data with no reference to style or execution.  The competition also focussed on an initial integration of automated objectivity into elite half-pipe snowboarding by awarding three separate prizes based on objective information judged solely by micro-technology.  Competition performances judged purely by objective measures were 1) Highest average air-time.  2) Highest average degree of rotation.  3) Highest individual air-time.  A World Cup and Olympic Games snowboard judge was appointed as the sole judge for the traditional subjective judging component associated with this competition.  Athletes were awarded an overall impression score out of 10 for each competition routine by this judge.  Objective data was provided by post-event processing of micro-technology outputs.  The athletes themselves were also asked immediately following the completion of the event to provide (anonymously) their selections associated with the top 5 athletic performances to award an athlete judged best rider award.  Athletes were provided with a 30 minute warm up period prior to the start of the competition.  All athletes had access to ‘over-snow’ transport (skidoo) providing them quick access to the top of the half-pipe following each warm up and competition run (Figure 7).  Athletes were allowed three runs to contest the traditional subjective judging component of the competition, the objective judging components of highest average air-time and highest average degree of rotation and the athlete judged best rider component.  The objectively judged highest individual air-time was decided with an additional two run format that immediately followed the main competition allowing each athlete the chance to perform only one aerial acrobatic manoeuvre per-run with the specific instruction to complete straight airs focussed on as much amplitude and air-time as possible. 

skidoo-transport

Figure 7. Australian athletes had access to "over-snow" transport during the AIS Micro-Tech Pipe Challenge to allow for effective use of the practice session and to ensure the competition itself was run in an efficient manner. Image: Jason Harding © www.AnarchistAthlete.com 2007

2.5 – Predicted Scoring Using Objective Data

Predicted scores and rankings were calculated using objective data in a multiple regression prediction equation based on previously established weightings.  Previous established weightings were derived from an unpublished video based analysis of an elite-level event conducted on the same half-pipe almost a year earlier (Burton Australian Open 2006).  The prediction equation included the key performance variables of average air-time and average degree of rotation:

PS = 11.424 AAT + 0.013 ADR – 2.223                               (1)

Where PS is the predicted score, the combined key performance variable, AAT is average air-time and ADR is average degree of rotation.

The prediction equation was determined by multiple linear regression (enter method) and displayed a very large correlation with subjectively judged scores at the 2006 Burton Open conducted on the same half-pipe course (r = 0.88 ± 0.11, p value < 0.001, r2 = 0.77, SEE = 2.82, n = 28).  Each run in the 2006 Burton Open event was scored out of 30 and as the 2007 AIS Micro-Tech Challenge event was scored out of a total 10 available points.  The predicted score generated by the aforementioned regression was subsequently divided by a factor of 3.  Data associated with predicted scores and subjectively judged scores were then examined to determine retrospectively if rankings would be any different if entire scores were established using automated objectivity. 

2.6 – Statistical Analysis 

This study allowed a criterion (subjectively judged scores) referenced validation of predicted competition scores (objective practical measure) associated with 18 cleanly completed runs performed during the AIS Micro-Tech Pipe Challenge.  Cleanly completed runs were deemed to be competition aerial acrobatic routines performed without major mistakes such as falls, stops, placing hands onto snow surface upon landing and associated losses of momentum.  All correlations are presented as correlation co-efficient ( r ) ± 95% confidence limits, p value (p), goodness of fit ( r2 ), standard error of the estimate (SEE) and sample size (n).  All mean bias results are presented as mean bias ± 95% confidence limits.  All correlations ( r ), goodness of fit statistics ( r2 ), standard error of the estimates (SEE), and p-values were calculated using SPSS 13.0 for Windows (Graduate Student Version).  All confidence limits (CL) and mean bias calculations were performed using excel spreadsheets provided by [11].  All confidence limits were set at 95% and statistical significance was set at p < 0.05.  Stacked graphs were generated using Prism graphing software (version 4.01).  The 3D scatter graph was generated with triplet data sets using Sigma Plot software (version 8.00). 

3- RESULTS

3.1 – Objective And Subjective Competition Data

The use of micro-technology based automated objectivity can potentially allow coaches, athletes and judges access to information pertaining to half-pipe snowboard competitions that has previously been unavailable.  Table 1 shows the objective key performance variable information associated with total air-time (TAT), average air-time (AAT), highest individual air-time (HIAT), total degree of rotation (TDR), average degree of rotation (ADR), highest individual degree of rotation (HIDR) and highest cumulative degree of rotation (HCDR), the subjectively judged competition scores awarded for each run and the overall position for each athlete.  A total of 18 cleanly completed runs out of a possible 30 were performed throughout the 2007 AIS Micro-Tech Pipe Challenge and not all athletes were able to perform more than one completely clean competition run. Any run deemed to have suffered from falls, stops, major places of hands onto snow following aerial acrobatic landings and associated losses of momentum were removed from the retrospective analysis.  The scores shown in Table 1 were provided by the subjective judge throughout the competition.  The objective key performance variable information shown in Table 1 was analysed post-competition from data obtained from micro-technology sensors.

3.2 – Air-Time And Degree Of Rotation In The 2007 AIS Micro-Tech Pipe Challenge

There is a strong practice community perception that air-time and degree of rotation play important roles in elite-level half-pipe snowboarding competition success however it is only ever assessed subjectively.  The information generated by micro-technology following the 2007 AIS Micro-Tech Pipe Challenge provided objective support for this practice community perception.  Average air-time and average degree of rotation were selected as the most important key performance variables within the 2007 AIS Micro-Tech Pipe Challenge based on their correlation to score (r = 0.48 ± 0.38, p = 0.04, r2 = 0.23, SEE = 1.67, n = 18 and r = 0.87 ± 0.14, p < 0.001, r2 = 0.76, SEE = 0.94, n = 18 respectively) and on their relevance to elite-level half-pipe snowboarding performance (Figure 8A and Figure 8B respectively).  Individually, average air-time and average degree of rotation can account for approximately 23% and 76% (respectively) of the shared variance associated with an athlete’s subjectively judged score (Figure 8A and Figure 8B respectively).  When combined in a multiple linear regression however,

PS = 3.421 AAT + 0.011 ADR – 1.794                     (2) 

Where PS is the predicted score, the combined key performance variable, AAT is average air-time and ADR is average degree of rotation.

they show a very strong correlation and can account for approximately 80% of the shared variance associated with an athlete’s subjectively judged score within the 2007 AIS Micro-Tech Pipe Challenge (r = 0.89 ± 0.11, p < 0.001, r2 = 0.80, SEE = 0.88, n = 18) (Figure 8C).  It is important to note that the key performance variable of total air-time also showed a very large correlation (the same as average air-time) to an athlete’s subjectively judged score within this event however it was not selected as a variable entered into the multiple regression analysis as it was deemed to rely heavily on the number of aerial acrobatic manoeuvres performed throughout a routine; something not always associated with a high level of performance in competition by the half-pipe snowboard community.

It is the combination of average air-time and average degree of rotation that is important in half-pipe snowboarding competition.  In this particular competition (2007 AIS Micro-Tech Pipe Challenge), average degree of rotation explained a large amount of the shared variance in scores (Figure 8B).  The combinations of average air-time and average degree of rotation that achieved specific subjectively judged scores within this competition are displayed in the 3D scatter plot in Figure 9.  There are a number of things to note within this graph.  1) Average air-time and average degree of rotation do have an effect on competition scores however an athlete must achieve highly on both to be awarded high competition scores.  In this event, a run with a combination of an average air-time over 1.2s and an average degree of rotation over 400 degrees provided an athlete with a score that placed them into one of the top 4 highest overall positions.  2) Athletes who focussed on average air-time only and not on the amount of rotations did not achieve high scores. For example; for an average air-time of 1.29s there is a large effect of average degree of rotation from 180 to 420 degrees which takes an athlete’s score from 4.2 to 8.0.  In this particular competition average degree of rotation played a major role in successful outcomes.  3) An athlete needs a certain amount of air-time in order to be able to achieve high degree of rotations.  Average air-times under 1.2s seemed to provide little opportunity to achieve high degree of rotations.  4) It was also interesting to note that for an average degree of rotation of approximately 250 degrees it did not seem to matter whether airtime goes from 1 to 1.4 s. 

3.3 – Criterion Referenced Validation Of Predicted Scores

This study allowed a criterion (subjectively judged scores) referenced validation of predicted (using purely objective data) competition scores (Figure 10A) and rankings (Figure 10B) associated with 18 cleanly completed runs performed during the 2007 AIS Micro-Tech Pipe Challenge.  The capacity of purely objective information used within the previously weighted prediction equation (Equation 1) to generate scores and rankings associated with the 2007 AIS Micro-Tech Pipe Challenge is shown in (Table 2, Figure 10A) and (Table 2, Figure 10B) respectively.  Scores predicted using equation 1 (practical measure) displayed a very large correlation to actual subjectively judged competition scores (criterion measure) achieved in the 2007 AIS Micro-Tech Pipe Challenge and could account for approximately 74% of the shared variance associated with subjective judging using purely objective information (r = 0.86 ± 0.14, p < 0.001, r2 = 0.74, SEE = 0.97 x 1.43, n = 18).  The mean bias between the criterion and practical measures of air-time was -0.65 ± 0.59 and the 95% confidence limits related to the mean bias were -1.24 and -0.06.   The prediction equation (practical measure) additionally displayed an almost perfect correlation to actual subjectively judged competition rankings (criterion measure) achieved in the 2007 AIS Micro-Tech Pipe Challenge and could account for approximately 82% of the shared variance associated with subjective judging using purely objective information (r = 0.90 ± 0.17, p < 0.001, r2 = 0.82, SEE = 1.38 x 1.54, n = 10).  The mean bias between the criterion and practical measures of air-time was 0.00 ± 0.77 and the 95% confidence limits related to the mean bias were -0.77 and 0.77.   

Table 1.  Key performance variable information associated with each ‘clean run’ during the AIS Micro-Tech Pipe Challenge.  Data is shown in descending order of subjectively judged score. Not all athletes completed more than one ‘clean run’ throughout the competition.  Subjectively judged scores were generated by the competition judge during the competition.  Objective information pertaining to average air-time, average degree of rotation and highest individual air-time were analysed immediately post competition for the provision of the awards judged purely by objective measures.  – - denotes second or third cleanly completed runs associated with a particular athlete (same bib number) that was not used to generate a final score or ranking as the run did not achieve that athlete’s best score.  As described in section 2.3, an aerial acrobatic manoeuvre containing no sport specific rotational component still generates a value of 180 degrees as the athlete turns through approximately 180 degrees taking off and landing on the same half-pipe lip [4].  The first meaningful sport specific rotational acrobatic manoeuvre is a 360 degree rotation.  A value of zero (0) in the HCDR column denotes that the athlete did not perform any aerial acrobatics that had rotational components in a consecutive series (more than one manoeuvre consecutively) i.e. All aerial acrobatics with a rotational component were performed singularly with straight airs (aerial acrobatics with no rotational component) in between each rotational acrobatic.

Rider

(bib)

Score

(points)

Final

Ranking

TAT

(secs)

AAT

(secs)

HIAT

(secs)

TDR

(deg)

ADR

(deg)

HIDR

(deg)

HCDR

(deg)

 

 

 

 

 

 

 

 

 

 

10

9.20

1

6.28

1.26

1.52

3240

648

900

3240

8

9.00

2

7.78

1.30

1.46

2880

480

720

2520

2

8.50

3

6.94

1.39

1.48

2520

504

720

1260

8

8.00

- -

7.76

1.29

1.38

2520

420

720

1440

2

7.70

- -

6.36

1.27

1.46

2520

504

720

2340

7

7.60

4

7.34

1.22

1.5

2880

480

720

2520

7

7.20

- -

7.40

1.23

1.46

2520

420

720

2160

2

6.50

- -

6.72

1.34

1.46

2160

432

720

1260

5

5.60

5

8.22

1.37

1.5

1260

210

720

0

1

5.50

6

5.14

1.29

1.44

1080

270

540

0

3

5.20

7

8.24

1.18

1.34

1440

206

360

0

4

5.00

8

6.30

1.26

1.44

1980

396

720

1620

6

4.80

9

5.86

0.98

1.4

1440

240

540

0

3

4.60

 –

7.98

1.33

1.4

1080

180

180

0

6

4.50

 –

6.32

1.05

1.24

1440

240

540

0

3

4.20

 –

7.76

1.29

1.42

1080

180

360

0

6

4.00

 –

6.02

1.00

1.24

1440

240

540

0

9

3.40

10

6.94

1.16

1.48

1800

300

540

0

jason-harding-figure-8-website-image-compressed

Figure 8. The impact average air-time (A), average degree of rotation (B) and the multiple linear regression of both average air-time and average degree of rotation (C) had with an athlete's subjectively judged score during the 2007 AIS Micro-Tech Pipe Challenge i.e. PS according to Equation 2. Bold lines denote the linear regression line; dashed lines denote the 95% confidence limits.

  

jason-harding-figure-9-3d-scatter-plot-ii-resized-for-website

Figure 9. 3D scatter plot displaying the effects average air-time and average degree of rotation had on an athlete's subjectively judged competition score during the 2007 AIS Micro-Tech Pipe Challenge. It is the combination of average air-time and average degree of rotation that is important in half-pipe snowboarding competition and in this particular competition average degree of rotation explained a large amount of the shared variance in scores. The winning run shown in Cluster 1 (performed by rider bib number 10) in this competition achieved an average air-time and an average degree of rotation of 1.26s and 648 degree respectively. The run achieved only equal 8th highest average air-time however achieved the highest average degree of rotation. Average degrees of rotation over 400 degrees however is only possible with average air-times over 1.2s on this particular half-pipe course (cluster 1 and 2). Cluster 1 (actual score 9.2): maximal ADR, average AAT; Cluster 2 (actual score 5-9): average ADR, average to high AAT; Cluster 3 (actual score 4-4.8): minimal ADR and AAT; Cluster 4 (actual score 4.2-5.6): minimal ADR, average to high AAT.

 

jason-harding-figure-10-resized-for-website

Figure 10. The capacity of a previously weighted multiple regression equation (1) derived from the 2006 Burton Open using objective data (practical measure) pertaining to average air-time and average degree of rotation to predict actual subjectively judged scores (A) and rankings (B) (criterion measure) achieved in the 2007 AIS Micro-Tech Pipe Challenge i.e. PS according to Equation 1 divided by 3. Bold lines denote the linear regression line; dashed lines denote the 95% confidence limits.

 

Table 2.  Competition scores (both actual and predicted) and associated final rankings (both actual, predicted and athlete judged) achieved in the 2007 AIS Micro-Tech Pipe Challenge.  Athletes perceived the top 4 competition places exactly the same as the subjective judge whilst rankings derived by micro-technology and the objective prediction equation (predicted rankings) switched the 2nd and 3rd rankings.  The prediction equation also ranked the 1st and 4th positions the same as the athletes and the subjective judge.  Interestingly the athletes perceived the 5th ranking position exactly the same as micro-technology and the objective prediction equation whilst the subjective judge ranked that particular run in 8th position. – - denotes second or third cleanly completed runs associated with a particular athlete (same bib number) that was not used to generate a final ranking as the run did not achieve that athlete’s best score. 

Rider

(bib no)

Actual

Score

Actual

Ranking

Predicted

Score

Predicted

 Ranking

 Athlete Judged

 Top 5 Ranking

 

 

 

 

 

 

10

9.20

1

6.85

1

1

8

9.00

2

6.28

3

2

2

8.50

3

6.73

2

3

8

8.00

- -

6.00

- -

- -

2

7.70

- -

6.29

- -

- -

7

7.60

4

6.00

4

4

7

7.20

- -

5.78

- -

- -

2

6.50

- -

6.25

- -

- -

5

5.60

5

5.39

6

- -

1

5.50

6

5.32

7

- -

3

5.20

7

4.63

- -

- -

4

5.00

8

5.77

5

5

6

4.80

9

4.02

10

- -

3

4.60

- -

5.10

8

- -

6

4.50

- -

4.31

- -

- -

3

4.20

- -

4.96

- -

- -

6

4.00

- -

4.12

- -

- -

9

3.40

10

4.96

9

- -

4- DISCUSSION

Half-pipe snowboard competition is now an Olympic sport and growing in popularity. Like other sports that rely on subjective judging criteria the methodology underpinning how coaches routinely assess athletic progression and judges score competition performance is open for debate and discussion. In terms of elite-level competition judging we have previously uncovered an awareness by the practice community of sport’s overall self annihilating teleology [5] occurring within elite-level half-pipe snowboarding [1, 2].  This concept theorises that increased numbers of athletes competing within a specific sporting discipline can eventually achieve optimal performance and thereby outgrow the structure of existing performance assessment measures. From an Olympic perspective, subjective judging protocols are also open for manipulation and corruption. The purpose of the current research was to explore the utility of incorporating micro-technology to enhance the “fairness” of judging world class snowboard athletes.  Based on previous research conducted by our group we constructed a snowboard competition that would require athletes to compete whilst instrumented with inertial sensors.  Objective data collected during competition was then compared to subjectively established scores and rankings made by an expert judge and the athletes themselves unaware of objective data obtained by inertial sensors. In addition we hosted a special event where the overall rankings were established entirely based on inertial sensor data to gauge the acceptance of this objective evaluation approach within an elite snowboard community. 

There is a strong practice community perception that air-time and degree of rotation play a major role in half-pipe snowboard competition success however these variables are currently assessed by purely subjective measures [1, 2].  Two quotes from a recently published study [2] described the perceived importance air-time has on competition performances.  ‘Air-time is considered for every trick from a judging perspective’ and ‘Athletes, coaches, judges, even my own mother agree that the amplitude [associated] with a trick is important’. Although there is a strong practice community perception of the importance of degree of rotation in competition performance there is mixed reaction to this component of the sport.  The ‘spin to win approach’ is a practice community concept that denotes the increasing amount of importance aerial acrobatic degree of rotation is showing in competition results.  This competitive approach, where athletes often increase the number of rotations during each aerial acrobatic manoeuvre performed throughout a half-pipe snowboard run, is not wholly endorsed by all of the practice community.  It is perceived to remove the valued components of air-time, amplitude, style and execution throughout a competition run in an attempt to increase the total and average degree of rotation.  In a recent study of the perception of elite-level judges to the integration of automated objectivity into competition judging protocols, all stated promoting objective information on degree of rotation within competitions could negatively impact the sport’s future directions [2].  Focusing on degree of rotation was largely perceived to promote a ‘spin to win’ approach to competition; an approach strongly opposed by elite-level judges as noted by the following judges’ comment.  ‘As for rotation, it seems to have played an increasing role in separating rider’s scores over the years but I feel this has sometimes been in error. Not everybody agrees with the “spin to win” approach. More [rotations] is not necessarily better. Of course having said that, a rider who does large degree rotations must be rewarded, provided they have been executed well’ [2].  Although the experienced snowboard community are trained to recognise rotational aerial acrobatics and there seems to be an underlying issue with the promotion of degree of rotation as a major determinant of competition outcomes, there is potential for automated acrobatic classification to allow competition judges to focus their attention on the more subjective and stylistic aspects of performance.

We have previously shown that air-time can now be accurately and reliably calculated using tri-axial accelerometer data and that aerial acrobatics can now be reliably classified into sport specific rotational groups using a combination of tri-axial accelerometer and tri-axial rate gyroscope data [3, 4].  There are also a number of studies that have recently focussed on the objective kinematical information associated with technical skill based sports such as snowboarding with the potential to generate similar data.  An electromagnetic tracking system has been used to quantify angular displacement and joint moment torques related to snowboard turns [12] and the same system has been used to calculate the degree of dorsiflexion, eversion and external rotation of the ankle joint complex during on-snow trials of snowboard boots [13].  We feel that although this system could potentially generate objective information on air-time and degree of rotation in a similar manner, the bulky electromagnetic tracking system worn by the subject and the ten kilogram measurement system carried by the researcher tethered to the subject would constrict and alter normal athletic movement patterns thus removing any relevance to real life snowboarding technique.  One study focussed on the development and in-field data acquisition of load components transmitted between boots and snowboard bindings [14] could however potentially be used to calculate objective information on air-time and degree of rotation in half-pipe snowboarding.  The absence of weight, size and tether in this monitoring device would allow half-pipe snowboard athletes to move freely and perform just as they would when not under scientific scrutiny. The technology is therefore subsequently available to assist elite-level coaches and competition judges in an objective manner. 

These recent developments have the potential to enhance the accuracy and reliability of current subjective judging protocols and possibly prevent (or at least delay) what has been perceived by some as the judging system’s inevitable self-annihilation.  In addition to practice community perceptions on the importance of air-time and degree of rotation in competition there is now objective evidence to support these claims.  In this study we used multiple regression techniques and included two major variables; average airtime and average degree of rotation.  When combined in a multiple regression (enter method), these two key performance variables displayed a very large correlation with subjectively judged scores awarded during the 2007 AIS Micro-Tech Pipe Challenge (r = 0.89 ± 0.11, p < 0.001, r2 = 0.80, SEE = 0.88, n = 18) and could account for approximately 80% of the shared variance in these competition scores (Figure 8C).  This provides objective support for the practice community’s perceptions on the importance of air-time and degree of rotation in competition success.  Interestingly 76% of the shared variance on subjectively judged scores could be accounted for by average degree of rotation alone (Figure 8B) providing objective evidence of the increasing importance of degree of rotation in competition scores.  The large amount of shared variance explained by average degree of rotation in the 2007 AIS Micro-Tech Pipe Challenge however seemingly contradicts the negative perception of competition judges to the ‘spin to win’ approach.

Although coaches are aware of the importance air-time and degrees of rotation have on competition scores, most assess athletic performance during routine training sessions in a purely subjective manner.  It is proposed the type of objective information generated by micro-technology during half-pipe snowboarding as shown in this paper could be used to enhance the current coaching protocols and provide a simple objective method to monitor athletic performance progression.  For example objective information generated during the 2007 AIS Micro-Tech Pipe Challenge showed that although average air-time and average degree of rotation did have an effect on subjectively judged scores, an athlete had to achieve highly in both components to produce successful competition performances.  In this particular event, a competition run with a combination of an average air-time over 1.2s and an average degree of rotation over 400 degrees provided an athlete with a score that placed them into one of the top 4 highest overall positions.  It is believed this information alone would provide coaches and athletes who did not perform well in this competition specific objective training targets for future competitive preparation (specifically for competitions to be conducted on the same half-pipe course).  Furthermore athletes who seemed to focus only on average air-time and not on the amount of rotations they performed during their competition runs did not achieve high scores in this particular competition.  For an average degree of rotation of approximately 250 degrees it did not seem to matter whether airtime increased from 1 to 1.4 s (Figure 9).  For an average air-time of 1.29s however there was a large effect of average degree of rotation from 180 to 420 degrees which increased an athlete’s score from 4.2 to 8.0 (Figure 9).  Although average degree of rotation was a major factor determining competition performance in this event, it was also shown that an athlete needs a certain amount of air-time in order to be able to achieve high degree of rotations.  For example average air-times under 1.2s seemed to provide little opportunity to achieve high degree of rotations (Figure 9).  Coaches are experienced in subjectively assessing both air-time and degree of rotation however we believe the information that can be generated by micro-technology (as shown during the 2007 AIS Micro-Tech Pipe Challenge) can be successfully utilised to assist coaches routinely monitor the performance of their athletes in a more objective manner and subsequently allow them to shift some of their subjective assessments toward the more stylistic components of half-pipe snowboarding performance.

We have additionally shown in this paper that it is possible to utilise previously established weightings associated with the objective information on air-time and degree of rotation to predict current competition scores and rankings with no reference to the subjective components of style or execution.  A retrospective analysis of average air-time and average degree of rotation with previously established weightings (from the 2006 Burton Open half-pipe event conducted on the same half-pipe) showed a very large correlation (r = 0.86 ± 0.14, p < 0.001, r2 = 0.74, SEE = 0.97, mean bias = -0.69 ± 0.59, n = 18) with subjectively judged scores awarded in the 2007 AIS Micro-Tech Pipe Challenge (Table 2, Figure 10A).  Furthermore these predicted scores accounted for approximately 74% of the shared variance in competition results.  Additionally we could predict overall competition rankings with an almost perfect correlation with the actual competition rankings awarded in the AIS Micro-Tech Pipe Challenge (r = 0.90 ± 0.17, p < 0.001, r2 = 0.82, SEE = 1.38 x 1.54, n = 10) and account for approximately 82% of the associated shared variance (Table 2, Figure 10B).  Furthermore the athletes themselves perceived the top 4 competition results exactly the same as the subjective judge whilst rankings derived by micro-technology and the objective prediction equation ranked the 1st and 4th positions the same as the athletes and the subjective judge however switched the 2nd and 3rd rankings.  Interestingly the athletes perceived the 5th ranking position exactly the same as micro-technology and the objective prediction equation whilst the subjective judge ranked that particular run in 8th position.

Although our predictions of overall scores and rankings associated with this competition were good there was still approximately 26% of the total variance in athlete scores and 18% of the total variance in actual competition rankings that are unexplained.  It is theorised this unexplained variance is due to a number of important variables associated with the aerial acrobatic routines performed in half-pipe snowboarding that can only ever be assessed with human subjective perception.  These variables include the style and execution associated with each aerial acrobatic manoeuvre, the sequence and combination of aerial acrobatic manoeuvres, the amount of risk in the routine, the overall use of the half-pipe including the line taken through the course and how the run progresses and flows.  The fact that we could not explain one hundred percent of the shared variance associated with athletic performance within this competition using purely objective information should not be considered a weakness of this approach but in fact a strength as the future of the sport may be best guided a judging criteria that incorporates both objective and subjected criteria similar to mogul skiing (time and judges), and ski jumping (distance and judging). 

It is theorised the integration of objectivity into judging protocols could in some ways address the practice community perception that a judging system based on the subjective perception of style and execution is a weakness in elite-level half-pipe snowboarding performance assessment [2].  There is however limits to the capacity of automated objectivity to address this issue. For example, the practice community sampled somewhat paradoxically stated that the subjective perception of style and execution is also the main strength associated with the current performance assessment method used in half-pipe snowboarding.  The practice community also unanimously opposed judging using objective information alone as it would remove what it considered to be prevailing judging strengths; that there is subjective perception of style and run execution and that the current competition platform allows freedom of expression and an opportunity to showcase individual style and flair [1, 2].  An amalgamation of automated objectivity with current subjective measures was however positively perceived by the practice community as it was believed to improve judging reliability and still retain what the practice community values.  This paper therefore proposes additional trials in collaboration with the half-pipe snowboarding community (Figure 11) to assess the potential of automated objectivity to initially provide objective assistance to competition judges. 

5- CONCLUSION

This paper has shown objective evidence of the importance air-time and degrees of rotation have in half-pipe snowboard competition subsequently supporting practice community perceptions.  These key performance variables however are currently assessed by purely subjective measures during both coaching and competition judging.  We have previously shown that objective information relating to air-time and degree of rotation associated with aerial acrobatic manoeuvres in half-pipe snowboarding can be accurately and reliably calculated using micro-technology and basic signal processing techniques.  This is proposed to assist coaches and judges in their quest to reliably assess athletic performance and to provide them with the capacity to shift their focus to the more stylistic components of the sport.  In an effort to conduct an initial integration of this concept we recently hosted an invitational half-pipe snowboarding competition (2007 AIS Micro-Tech Pipe Challenge) designed to evaluate whether the snowboard community would embrace a competition where results were in part determined by automated objectivity, explore the practical, logistical and technical challenges associated with conducting such an event and most importantly evaluate the relationship between subjective judging and results predicted from objective information to see if prior research had ecological validity.  Using nothing more than objective information and a prediction equation based on previously established weightings for important key performance variables such as average air-time and average degree of rotation we were able to account for 74% of the shared variance associated with subjectively judged competition scores awarded during the 2007 AIS Micro-Tech Pipe Challenge.  This result provides further evidence of the importance air-time and degree of rotation have on competition score but also that there is potential to assess athletic performance in half-pipe snowboarding competition using a purely objective approach.  Although our predictions of overall scores were good there was still 26% of the total variance unexplained.  We do not consider this a weakness associated with this objective approach but in fact a strength as we believe the sport specific components of style, execution and how the routine progresses and flows can only be assessed via human subjective perception and should therefore never be removed from the sport.  The future of half-pipe snowboarding however may be best guided a judging protocol that incorporates both objective and subjective criteria and we propose additional trials of this concept be conducted in collaboration with the practice community in order to further assess this potential.

jason-harding-figure-11

 

 

 

 

Figure 11. Australian athletes alongside Australian national coach Ben Wordsworth and the contest organiser Jason Harding during the 2007 AIS Micro-Tech Pipe Challenge awards ceremony. This event focused on an initial integration of automated objectivity into elite half-pipe snowboarding in collaboration with the Australian snowboarding practice community. Image: Heidi Barbay © www.AnarchistAthlete.com 2007

6- ACKNOWLEDGMENTS

First and foremost, thank you to the snowboard coaches (Ben Wordsworth and Ben Alexander), the FIS World Cup half-pipe snowboard judge and the Australian snowboard athletes that took part in this competition for their willingness to trial innovative technology and challenge conventional competition judging formats. We also thank the Australian Institute of Sport, Australian Sports Commission, the Olympic Winter Institute of Australia, Griffith University’s Centre for Wireless Monitoring and Applications, Griffith University’s Department of Tourism, Leisure, Hotel & Sport Management, Griffith University’s Centre for Tourism, Sport and Service Innovation, Perisher Blue Ski Resort, Catapult Innovations and the NSW National Parks and Wildlife Service for all funding, sponsorship and in-kind support associated with the AIS Micro-Tech Pipe Challenge 2007 and previous research. A special thanks to the Head of the Department of Physiology at the Australian Institute of Sport, Professor Chris Gore and all his staff for creating an environment focussed on innovative thinking and passionate debate in the name of rigorous scientific enquiry. Thank you to the Head of the Department of Tourism, Leisure, Hotel & Sport Management at Griffith University, Professor Kristine Toohey for her insight into the potential impact of technological integration in elite sport and for her guidance in the subsequent sociological research. Also thank you to Heidi Barbay for her assistance during numerous southern hemisphere winters and to all the staff from the Department of Physiology at the Australian Institute of Sport, Griffith University’s Centre for Wireless Monitoring and Applications and Perisher Blue Ski Resort who helped conduct the AIS Micro-Tech Pipe Challenge; generating the data utilised in this paper. Results, background research, initial media exposure, photographs and video footage related to this competition can be can be viewed at www.AnarchistAthlete.com

7- REFERENCES

  1. 1. Harding JW, Toohey K, Martin DT, Mackintosh C, Lindh AM, James DA. Automated Inertial Feedback For Half-Pipe Snowboard Competition And The Community Perception. The Impact of Technology on Sport II, Fuss F. K., Subic A., Ujihashi S. Taylor & Francis London 2008 ; 20: 845 – 850.
  2. 2.  Harding JW, Toohey K, Martin DT, Hahn AG, James DA. Technology and Half-Pipe Snowboard Competition – Insight From Elite-Level Judges. The Engineering of Sport 7, Estivalet, M., Brisson, P. Springer-Verlag France 2008 ; 2: 467-476.
  3. 3.  Harding JW, Small JW, James DA. Feature Extraction of Performance Variables in Elite Half-Pipe Snowboarding Using Body Mounted Inertial Sensors, BioMEMS and Nanotechnology III, edited by Dan V. Nicolau, Derek Abbott, Kourosh Kalantar-Zadeh, Tiziana Di Matteo, Sergey M. Bezrukov, Proceedings of SPIE Vol. 6799 (SPIE, Bellingham, WA, 2007) 679917 2007.
  4. 4.  Harding JW, Mackintosh CG, Hahn AG, James DA. Classification of Aerial Acrobatics in Elite Half-Pipe Snowboarding Using Body Mounted Inertial Sensors.  The Engineering of Sport 7, Estivalet, M., Brisson, P. Springer-Verlag France 2008 ; 2: 447-456.
  5. 5.  Miah M. New Balls Please: Tennis, Technology, and the Changing Game. S. Haake and O. A. Coe 2000 Tennis, Science and Technology, Blackwell and Science, London 2005 ; 285-292.
  6. 6.  Tenner E. Why Things Bite Back: Predicting the Problems of Progress.  Fourth Estate, London 1996.
  7. 7.  Catapult Innovations. Mini Max. Catapult Innovations Melbourne Australia 2007.
  8. 8.  Mackintosh C., G. LOGAN V21.0 Copyright ©. Australian Institute of Sport, CRC for Micro-Technology 2004.
  9. 9.  James DA, Davey N, Rice T. An Accelerometer Based Sensor Platform for Insitu Elite Athlete Performance Analysis. In IEEE Sensors Conference Vienna 2004 : 24-27 October.
  10. 10.  Green J, Krakauer D. New iMEMS® Angular-Rate-Sensing Gyroscope. In Analog Dialogue 2003; 37: 3.
  11. 11.  Hopkins W.G. Analysis of validity by linear regression (Excel spreadsheet).  A new view of statistics. sportsci.org: Internet Society for Sport Science, sportsci.org/resource/stats/xvalid.xls 2005; viewed on 25 September 2008.
  12. 12.  Doki H, Yamada T, Nagai C. Horaki, M. Development of a measurement system for snowboarding turn analysis. The Impact of Technology in Sport, Subic, A., and Ujihashi, S. Taylor & Francis London 2005; 324 – 325.
  13. 13.  Delorme S, Tavoularis S. Kinematics of the Ankle Joint Complex in Snowboarding. Journal of Applied Biomechanics 2003; 21 : 394-403.
  14. 14.  Bianchi L, Petrone N, Marchiori M. A dynamometric platform for load data acquisition in snowboarding: design and field analysis.  The Engineering of Sport 5, Hubbard, M., Mehta, R. D., Pallis, 2004; 2 : 187-193.

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