INTRODUCTION:
The Powercranks use an independent clutch design to maximize use of the hip flexors during the upward pull phase of the pedal stroke. This may improve gross cycling efficiency by increasing the amount of work performed per unit of energy expenditure.
PURPOSE:
To examine the effects of 6 weeks of training in well-trained endurance cyclists using Powercranks (n = 6) or normal cranks (n = 6) on maximal oxygen uptake (VO2max) and anaerobic threshold (AT) during a graded exercise test (GXT), and heart rate (HR), oxygen consumption (VO2), respiratory exchange ratio (RER), gross efficiency (GE), and blood lactate concentration ([La]) during a 1-h constant load ride.
METHODS:
Subjects in both groups performed supervised training on a cycle ergometer for 1-h, 3 d.wk-1 for 6 wk, with training intensity set at 70 percent of VO2max. The GXT and 1-h submaximal test was performed using normal cranks pre- and post-training to assess differences in the variables tested. The 1-h submaximal ride was performed at 70 percent of VO2max. VO2, RER, GE, and HR were determined at 15-min intervals during the 1-h submaximal test. Blood [La] was determined from samples collected pre- and post-exercise.
RESULTS:
No significant differences were observed between or within groups for VO2max or AT during the GXT. The Powercranks group had significantly higher GE values than the Normal Cranks group (23.6 ± 1.3 percent versus 21.3 + 1.7 percent, and 23.9 + 1.4 percent versus 21.0 + 1.9 percent at 45 and 60 min., respectively), and significantly lower HR and VO2 values during the 1-h submaximal ride following training. No significant differences in blood [La-] or RER were reported.
CONCLUSION:
These results indicate that 6 weeks of training with the Powercranks reduces energy expenditure during a 1-h submaximal ride compared to training with normal cranks. The use of the Powercranks during training may improve submaximal cycling performance during competition.
