Influence of crank length and crank-axle height on standing arm-crank (grinding) power.
OBJECTIVE
To determine the optimal crank length and crank-axle height for maximum power production during standing arm cranking ("grinding").


METHODS
Nine elite professional America's Cup grinders (age = 36 +/- 2 yr, body mass = 104 +/- 1 kg, body fat = 13% +/- 2%) performed eight maximal 6-s sprints on an adjustable standing arm-crank ergometer fitted with an SRM power crank. The protocol included crank lengths of 162, 199, 236, and 273 mm and crank-axle heights of 850, 950, 1050, and 1150 mm. Peak power, ground reaction forces, and joint angles were determined and compared for different crank lengths and crank-axle heights with repeated-measures ANOVA.


RESULTS
Peak power was significantly different between crank lengths (P = 0.006), with 162 mm lower than all others (P < 0.03). Optimal crank length was 12.3% of arm span or 241 +/- 9 mm for this cohort of athletes. Peak power was significantly less for the crank-axle height of 850 mm compared with 1150 mm (P = 0.01). The optimal crank-axle height for peak power was between 50% and 60% of stature (950-1150 mm in this study). Hip flexion was greater at the lowest crank-axle height (850 mm) than at 1050 and 1150 mm (P < 0.01), and the resultant ground reaction force was also reduced compared with all other heights, indicating greater weight bearing by the upper body.


CONCLUSIONS
Changes in crank length and crank-axle height influence performance during maximal standing arm-crank ergometry. These results suggest that standard leg-cycle crank lengths are inappropriate for maximal arm-cranking performance. In addition, a crank-axle height of <50% of stature, which is typically used in America's Cup sailing, may attenuate performance.
Neville
Vernon
V
Sports Technology Institute, Loughborough University, Leicestershire, United Kingdom. dswedler@jhsph.edu
Pain
Matthew T G
MT
Kantor
Jonathan
J
Folland
Jonathan P
JP
D000328:Adult; D000886:Anthropometry; D001132:Arm; D004867:Equipment Design; D016552:Ergometry / Q000295:instrumentation; D006801:Humans; D008297:Male; D008328:Man-Machine Systems; D053580:Muscle Strength; D011187:Posture; D012767:Ships; D013177:Sports; D013647:Task Performance and Analysis; D019415:Torque