A simple isokinetic cycle for measurement of leg muscle function

The measurement of net pedaling torque during isokinetic cycling allows for the evaluation of leg muscle strength and work capacity over fixed time intervals. However, the expense and difficulty of constructing an isokinetic cycle have limited the widespread application of this useful research tool. We have modified a simple commercially available isokinetic cycle that uses hydraulics to maintain pedaling velocity. A strain gauge on the flywheel axle strut measures the torsion on the strut caused by pedaling. To evaluate this device, seven healthy subjects (3 males and 4 females) were each tested twice at 60, 90, and 120 rpm for peak power during a 10-s sprint and at 100 rpm for total work performed during a 30-s sprint. These results were compared with predicted values for age, height, and sex developed on a more complicated isokinetic cycle. Subjects also performed a progressive cycle ergometry test. For the group, peak power was 97.30 +/- 12.64% of predicted (males 883.70 +/- 202.76 W; females 657.00 +/- 66.42 W) and work output was 107.70 +/- 15.75% of predicted (males 15.50 +/- 2.85 kJ; females 11.70 +/- 2.17 kJ), whereas maximal progressive exercise capacity was 126.40 +/- 25.84% (males 245.30 +/- 56.58 W; females 212.30 +/- 35.49 W). The relatively lower work values generated on this cycle (compared with the maximal progressive exercise capacity) can be attributed to the location of the strain gauge, resulting in measurement of effective work output on the flywheel.(ABSTRACT TRUNCATED AT 250 WORDS)