SIMILAR EMG TO FORCE RATIOS IN SEDENTARY SUBJECTS AND SPRINTERS

1439 One method of assessing neural activation of muscles in different conditions or subject populations is to compare the EMG to force ratios. A long-debated issue is whether exercise training influences muscle activation with the implied hypothesis of athletes compared with sedentary subjects possessing a greater neuromuscular efficiency (i.e., a lower EMG to force ratio). Thus, we have compared EMG-to-force ratios in sedentary women (n = 21, age 21) and Olympic level male and female sprinters (n = 14, age 20). Subjects performed maximal effort isokinetic 90 °/s eccentric and concentric and isometric knee extensions on a dynamometer (Kin-Com, Chattanooga, TN). Surface EMG activity of the vastus lateralis was monitored and analyzed for the peak EMG activity (Noraxon, Scottsdale, AZ). The Table shows the EMG-to-force ratios (±S.D.) for each group of subjects under the 3 conditions and that the Group by Contraction mode interaction was not significant. The Contraction mode main effect was significant (F = 4.1, p = 0.0001); the eccentric (1.86 ±0.98) and isometric (2.59 ±1.29) ratios were significantly smaller than the concentric ratio (3.67±1.71). These data suggest that, as reported previously, the neural cost of muscle contraction is the least for eccentric and the greatest for concentric muscle actions. However, the current data suggest that the EMG-to-force ratios are independent of training status.Table