Interactive variable resistance exercise system concept and preliminary results

In order to maximize loading during resistance exercise, muscles should be heavily taxed throughout the entire range of motion for that exercise. Traditional constant resistance squats only tax the lower-extremity muscles to their limits at the "sticking region" or a critical joint configuration of the exercise cycle. Therefore, a Smith machine was modified for pneumatic resistance with appropriate computer control so that it is capable of adjusting force within a repetition of the squat exercise. The control program was designed to increase the loading after accelerating to a specified lifting velocity which indicates increased strength capacity from being past the sticking region. Human subject testing showed the percent increase from initial to final resistance level normalized by body and barbell weight was an average of 14% (+/-5%) for men and 29% (+/-14%) for women with both separately showing a significant increase in resistance level (p>0.00005 each). The men had significantly higher initial (p=0.007) and final (p=0.04) normalized resistance levels than the women. This investigation indicates that interactive variable resistance exercise is capable of significantly increasing the loading after a desired instantaneous velocity is reached; however, further performance testing is required to determine its efficacy.