Neuromuscular Responses During Vigorous Intensity Heart Rate-Clamp Cycling Exercise

Authors

• Clara J. Mitchinson, University of KentuckyFollow
• Pasquale J. Succi, Chestnut Hill CollegeFollow
• Brian Benitez, Stetson UniversityFollow
• Djadmann Gustave, University of KentuckyFollow
• Minyoung Kwak, University of KentuckyFollow
• Erik Snell, University of KentuckyFollow
• Haley C. Bergstrom, University of KentuckyFollow

Abstract

Introduction: Electromyography (EMG) and mechanomyography (MMG) provide non-invasive assessments of neuromuscular function and fatigue during dynamic exercise. This study examined neuromuscular fatigue and cycling performance through changes in power output (PO), total work (TW), EMG and MMG, amplitude (AMP) and mean power frequency (MPF) during three, heart rate (HR)-Clamp trials in the vigorous range (77-95% HR_max). Methods: Ten men (mean±SD, 25.9±5.0yr, 74.9±15.0kg, HR_max=178±12b×min^-1) performed a cycle ergometer graded exercise test, followed by three separate HR-Clamp trials at 77%HR_max (HR_L, time to exhaustion [T_Lim]=58.5±4.6 min, range=45.3-60.0min), 86%HR_max (HR_M, T_Lim=48.4±16.5 min, range=20.33-60.0min), and 95%HR_max (HR_H, T_Lim=9.0±6.7 min, range=2.0-22.0min) to exhaustion or up to 60 min. EMG and MMG signals were measured from the vastus lateralis, and the TW was calculated for each trial. One-way repeated measures ANOVAs and Bonferroni-corrected t-tests examined T_Lim and TW across HR-Clamp trials. Separate, 3 (Trial: HR_H, HR_M, HR_L) x 5 (Time: [0, 25, 50, 75, 100% T_Lim]) repeated measures ANOVAs with appropriate follow-up procedures were used to examine changes in PO, normalized EMG and MMG, AMP and MPF. Results: PO decreased relative to the initial value for each trial but generally plateaued between 25-75%T_Lim. TW was significantly lower for HR_H (109±72kJ) compared to HR_L (475±81kJ) and HR_M (460±162kJ) (all pL and HR_M (p=1.000). There were no significant differences at any time point for EMG and MMG AMP, and MMG MPF. However, there was a significant increase in EMG MPF (p=0.005) at 50%T_Lim, collapsed across Trial. Conclusions: There were limited changes in the EMG and MMG signals during HR-Clamp trials, supporting the idea that reductions in power output may offset some of the influence of metabolic byproduct accumulation to increase muscle excitation during sustained, vigorous cycle ergometry.

Recommended Citation

Mitchinson, Clara J.; Succi, Pasquale J.; Benitez, Brian; Gustave, Djadmann; Kwak, Minyoung; Snell, Erik; and Bergstrom, Haley C. (2026) "Neuromuscular Responses During Vigorous Intensity Heart Rate-Clamp Cycling Exercise," Journal for Sports Neuroscience: Vol. 2: Iss. 1, Article 10.
Available at: https://nsuworks.nova.edu/neurosports/vol2/iss1/10