Effects Of Short-term Strength Training With Recumbent-type Cycle Ergometer On Muscular Function Of Lower Limbs

Abstract

Evaluation of muscular function of lower limbs with a servo-controlled dynamometer (SCD) was previously reported (Yamauchi et al. 2004). PURPOSE We introduced the similar methodology to the recumbent-type cycle ergometer and investigated the effects of a 2-wk strength training with pedaling exercise on muscular function of lower limbs. METHODS 6 healthy untrained women (age, 18–27yr) were trained with pedaling exercise using a recumbent-type ergometer for 2 wk, preceded by a 2-wk of sedentary period (control). Training session consisted of 5 sets of 1 minute exercise at 30 rpm and with a 30s rest interval between sets. Intensity was 10,30,40,50 and 10% of the maximum isometric torque (Tmax) in each of 1st to 5th set for the first 7 days, thereafter increased by 10% in each set. Tmax was determined by a “stepwise loading method (S)” using an electromagnetic load control, in which the load was successively increased within a bout. The torque-velocity relation obtained with S showed no significant difference from that obtained with a conventional method, in which a varied load was applied to each bout independently. It was well described with a linear function, as previously shown in knee-hip extension movements (Yamauchi et al. 2004). The effects of training were evaluated by measuring Tmax and the extrapolated maximum unloaded rate of revolutionary (Rmax) with S. Also, the maximum isometric force (Fmax) and the unloaded velocity (Vmax) of knee-hip extension movements were measured with SCD. During knee-hip extension, EMGs were simultaneously recorded by using surface electrodes from knee-hip extensor muscles. RESULTS After initial 2-wk of sedentary period, all measured variables did not change significantly. After the training period, both Tmax and Rmax measured with the recumbent-type cycle ergometer did not change significantly, whereas both Fmax and Vmax measured with SCD increased by 9.4% and 11.2%, respectively (P<0.05, compared to pre-training values). This is consistent with the previous result on inertia-free strength training (Yamauchi et al. 2003), and suggests an improvement in muscular coordination. CONCLUSIONS Although the present training was specific to the movement for measurement (recumbent-type cycle), it failed to improve the pedaling performance. On the other hand, it caused increases in both force and velocity of the bilateral knee-hip extension, which is slightly different type of movement. Although the exact mechanism for this remains unclear, measurements using an explosive bout of movement may be more sensitive for detecting change in muscular coordination than measurements using repeated movements.