Stephanie. A. Sontag*1, Michael A. TrevinoƗ2, Adam J. SterczalaƗ1, Jonathan D. MillerƗ1, and Trent J. Herdaǂ1. 1University of Kansas, Lawrence, KS; 2Armstrong State University, Savannah, GA

Differences in motor unit (MU) control strategies have been reported as a function of chronic training. The effects of aerobic training on cardiovascular markers are well understood; however, less is known regarding the effects on neuromuscular behavior. PURPOSE: This study examined the effects of 10 weeks of continuous cycling training on maximal aerobic fitness (VO2MAX), maximal strength (MVC) of the leg extensors, and the electromyographic amplitude (EMGRMS)-force relationships for the vastus lateralis (VL). METHODS: Thirteen sedentary individuals (mean ± SD, age = 22.31 ± 5.34 yrs) completed 40 aerobic cycling training sessions over 10 weeks. Weeks 1 – 3 consisted of 30 mins of cycling at 70% of heart rate reserve (HRR), whereas, weeks 4 – 6 and 7 – 10 were 40 mins at 75% and 80% of HRR. Pre- and post-training, participants performed (1) incremental cycling to determine relative VO2MAX and maximal HR, and (2) MVC on an isokinetic dynamometer followed by a submaximal (70% relative to pre-training MVC) linearly increasing muscle action of the leg extensors. An EMG sensor was placed over the VL prior to strength. For the linearly increasing muscle action, linear regression models were fit to the log-transformed EMGRMS-force relationships and the slope (b term) was calculated. Separate paired samples t-tests were used to examine relative VO2MAX, MVC, and the b terms. Alpha was set at 0.05. RESULTS: There was a significant increase (P<0.001) in relative VO2MAX (Pre=34.38±6.89 ml/kg/min, Post=39.87±7.30 ml/kg/min) following 10 weeks of continuous cycling training. For MVC, there was no significant difference (P=0.442) between pre- (150.17±46.38 Nm) and post-training (147.30±48.46 Nm). In addition, there was no significant difference (P=0.901) for the b terms (Pre=1.099±0.188 µV/Nm; Post=1.106±0.214 µV/Nm) from the EMGRMS-force relationships. CONCLUSION: Ten weeks of continuous cycling training improved maximal aerobic capacity while maximal strength for the leg extensors was unaffected. The EMGRMS patterns of response (b terms) during an increasing muscle action were not different between pre- and post-testing and, thus, muscle activation for the VL was unchanged following 10 weeks of continuous cycling training.

This work was supported in part by a National Strength and Conditioning Association Foundation (NSCAF) Graduate Research Doctoral Grant.

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