APPLICATION OF NEUROMUSCULAR ELECTRICAL STIMULATION IN DEVELOPING ROWERS' MUSCLES

Abstract

INTRODUCTION Rowing technique can be divided into three categories by the characteristics of F-t curves. Category A emphasises the strength of the legs, Category B pays more attention to the cooperation of upper body and anns, and Category C emphasises the beginning of the rowing cycle and neglects the middle and end of the cycle. Different kinds of rowing style are the result of different habits and training, but they also reflect the conditions of specific muscle groups of each individual. Neuromuscular electrical stimulation is developed from clinical electrical stimulation. Many researchers are interested in its applications in sports training. Pan Huiju et al. found out that neuromucular electrical stimulation (NMES) has many advantages compared with direct muscle electrical stimulation. So we applied NMES to the rowers as a supplemental training method. METHODOLOGY 'henty elite male rowers in Zhejiang Rowing Team volunteered to take part in this study. The subjects were devided into two groups, group A received NMES from NMES-168 Stimulators every night plus normal training every day for two weeks, and the muscle groups that received NMES were decided by the features of their F-t curves measured with a strain gauge set in a Concept-I1 rowing ergometer. Group B was trained normally. Heart rates were monitored during the stimulations. Before the stimulations , two tests were done. Test 1 is to measure the blood lactate acid concentration (BLAC) 2 minutes after the 20 mins rowing with intensity of 1:50/500m and rowing frequency of 18 on a Concept -11 rowing ergometer. 10 mins after Test 1. Test 2 measured the time the rowers take to finish 2500 m on a Concept-two rowing ergometer. After two weeks of stimulation, the F-t curves, Testl and Test2 were done again. RESULTS AND DISCUSSION The F-t curves of both Group A and Group B were generally in better form after two weeks of intensive training. In Testl, the average BLAC of Group A decreased from 5.38mmoYI to 4.27 mmoV1, and the average BLAC of Group B decreased from 5.32 to 4.89 after the experiment. In Test2, the average time for rowing 2500m of Group A decreased from 8:20 to 8:03, and the average time for rowing 2500m of Group B decreased from 8:21 to 8: 11. Both tests showed that that all the rowers had significant progress after two weeks of conscious training, and that Group A had greater improvement. After measuring the Force-time curve, the rowers learned the weaknesses of their technique, and then trained with a definite aim to reach the best model. The improved technique of the rowers caused the decrement of BLAC after the same amount of training. Rowers of Group A not only know the features of their techniques through F-t measurement, but also adopt NMES to the weak part of the muscle groups besides normal training. That is why they got better results after two weeks of experimental training. During the stimulations, the heart rates of the subjects increased by 10- 15%. which were much smaller than those in general strength training. We concluded that by measuring F-t curves we can train the rowers according to the characteristics of each rower, and that NMES-168 played a positive role in the development of muscles of elite rowers.