Muscle Oxygenation Responses to Low-intensity Steady Rate Concentric and Eccentric Cycling

Area of Science:

• Exercise Physiology
• Sports Science
• Muscle Physiology

Background:

• Muscle deoxygenation during exercise provides insights into training load and adaptation.
• Understanding muscle oxygenation during different exercise types is crucial for optimizing training protocols.

Purpose of the Study:

• To investigate and compare muscle oxygenation profiles during prolonged low-intensity eccentric (ECC) and concentric (CON) cycling.
• To determine if muscle action type influences muscle oxygenation responses under matched metabolic conditions.

Main Methods:

• Twelve healthy men completed two 45-minute cycling sessions (ECC and CON) at matched initial heart rates.
• Measurements included oxygen uptake, blood lactate, cardiac output, blood pressure, and muscle oxygenation.
• Mechanical power output was significantly higher during ECC cycling compared to CON cycling.

Main Results:

• Oxygen uptake, blood lactate, and cardiac output did not differ between ECC and CON cycling.
• Heart rate increased progressively during ECC cycling and was higher than CON after 15 minutes.
• Despite higher power output and heart rate during ECC, muscle oxygenation profiles showed no significant differences between the two exercise types.

Conclusions:

• Muscle oxygenation responses during prolonged low-intensity exercise are not significantly affected by the type of muscle action (eccentric vs. concentric).
• This finding holds true when metabolic demand and cardiac output are maintained at similar levels.
• Muscle oxygenation monitoring may not differentiate training responses between eccentric and concentric cycling under these specific conditions.