Electromyographic adjustments during continuous and intermittent incremental fatiguing cycling

Area of Science:

• Exercise Physiology
• Biomedical Engineering
• Sports Science

Background:

• Electromyography (EMG) is crucial for understanding muscle activation during exercise.
• Differentiating between continuous and intermittent cycling protocols is important for exercise prescription and fatigue management.
• Identifying sensitive EMG parameters for load and fatigue is key to optimizing training and performance monitoring.

Purpose of the Study:

• To investigate the sensitivity of various EMG variables to exercise load and muscle fatigue during continuous and intermittent incremental cycling.
• To compare the effects of different cycling protocols on EMG signal characteristics.
• To determine the most suitable EMG parameter for monitoring muscle activation and fatigue during cycling.

Main Methods:

• Fifteen male participants completed incremental cycling tests under continuous and intermittent protocols.
• Multichannel EMG signals were recorded from the vastus lateralis muscle.
• Analysis included muscle fiber conduction velocity (MFCV), instantaneous mean frequency (iMNF), and absolute and normalized root mean square (RMS).

Main Results:

• MFCV differed between protocols and increased with power output only during intermittent cycling.
• RMS parameters increased linearly with power output, with normalized RMS being higher at 100% peak power output (PPO) in the continuous protocol.
• iMNF showed no significant sensitivity to load or fatigue (P = 0.14).

Conclusions:

• Continuous and intermittent cycling protocols differentially affect MFCV and normalized RMS.
• Normalized RMS is the most suitable EMG parameter, demonstrating sensitivity to both power output increases and muscle fatigue.
• Normalized RMS can effectively monitor changes in muscle activation during cycling exercise.