Proactive balance strategy while maintaining a stationary wheelie.
OBJECTIVE
To test the hypothesis that a reactive balance strategy is used while maintaining a stationary wheelie, specifically that a forward pitch from the wheelie equilibrium position is associated with a forward displacement of the wheelchair and a rear pitch with rear displacement, with the displacement slightly after the change in pitch.


METHODS
Descriptive and quantitative kinematic analysis.


METHODS
Kinesiologic laboratory.


METHODS
A convenience sample of 10 able-bodied adults.


METHODS
Subjects taught to pop and maintain a stationary wheelie for 15 seconds while remaining within a .75 x .75 m2. Three trials of 5 seconds; digitized targets videotaped for analysis.


METHODS
Pitch angle and rear-wheel position of the wheelchair, derived from digitized videotape and time-series analysis of phase lag.


RESULTS
There was an inverse relationship between the direction of pitch and linear displacement-rear pitch was associated with forward wheel displacement and forward pitch was associated with rearward wheel displacement. The mean pitch angle +/- standard deviation was 13.6 degrees +/- 2.3 degrees and the mean horizontal position of the wheelchair was 0.0 +/- 4.9cm. There was little or no phase lag between pitch and displacement.


CONCLUSIONS
Wheelie performers maintaining a stationary wheelie appeared to use a proactive balance strategy, in which they used a functional base of support that was larger than the geometric one. These findings may have significance for those who are learning and teaching wheelies and provide broader insights into the nature of dynamic balance.
Bonaparte
J P
JP
School of Health and Human Performance, Dalhousie University, Halifax, NS, Canada.
Kirby
R L
RL
Macleod
D A
DA
D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D012046:Rehabilitation; D014743:Videotape Recording; D014910:Wheelchairs