EFFECTS OF CONTINUOUS CYCLING TRAINING ON MOTOR UNIT BEHAVIOR DURING CONSECUTIVE CONTRACTIONS IN SEDENTARY MALES
Michael A. Trevino1, Adam J. Sterczala2, Jonathan D. Miller3, Mandy E. Wray3, Hannah L. Dimmick4, and Trent J. Herda3. 1Oklahoma State University, Stillwater, OK; 2University of Pittsburg, Pittsburgh, PA; 3University of Kansas, Lawrence, KS; 4University of Calgary, Calgary, Alberta.
PURPOSE: To examine the effects of a 10 week continuous cycling intervention on maximal aerobic capacity (VO2MAX), maximal strength (MVC) of the leg extensors, and MU behavior of the vastus lateralis (VL) in previously sedentary males. METHODS: Nine males completed 40 supervised training sessions. Pre-and post-intervention, participants performed a cycling VO2MAX test and MVCs on an isokinetic dynamometer followed by two consecutive submaximal (40% relative to pre-training MVC) contractions of the right leg extensors. Surface electromyographic (EMG) decomposition assessed recruitment thresholds (RT), motor unit action potential amplitudes (MUAPAMPS) and mean firing rates (MFR) for each observed MU from the VL for the 40% MVCs and linear regressions determined the y-intercepts (y-ints) and slopes for the MFR and MUAPAMP vs. RT relationships. EMG amplitude for the 40% MVCs was normalized (N-EMG) to the MVC for the current visit. Separate paired samples t-tests examined VO2MAXand MVC. Separate two-way ANOVAs (time x repetition) examined N-EMG and the y-ints and slopes for the MFR vs. RT and MUAPAMP vs. RT relationships. Alpha was 0.05. RESULTS: Ten weeks of training resulted in significant increases in VO2MAX (P =0.005) while MVC was unchanged (P = 0.056). For the slopes and y-intercepts from the MFR and MUAPAMP vs. RT relationships, there were no significant two-way interactions (P = 0.152 –0.669) or main effects for time (P = 0.213 –0.753) or repetition (P = 0.313 –0.639). For N-EMG, there was no significant two-way interaction (P = 0.485). There were main effects for time (P = 0.035) and repetition (P = 0.044). N-EMG was greater for post-training and repetition 2 when collapsed across time and repetition. CONCLUSION: As expected, continuous cycling increased maximal aerobic capacity. Although maximal strength of the leg extensors and firing rates in relation to recruitment thresholds for the VL were unchanged following the cycling training program, participants exhibited greater muscle activation and decreased fatigue resistance when completing consecutive contractions at pre-training absolute torque levels.
Trevino, MA; Sterczala, AJ; Miller, JD; Wray, ME; Dimmick, HL; and Herda, TJ
"EFFECTS OF CONTINUOUS CYCLING TRAINING ON MOTOR UNIT BEHAVIOR DURING CONSECUTIVE CONTRACTIONS IN SEDENTARY MALES,"
International Journal of Exercise Science: Conference Proceedings: Vol. 11:
7, Article 75.
Available at: https://digitalcommons.wku.edu/ijesab/vol11/iss7/75