Muscle Oxygenation During Running Assessed by Broad Band NIRS

Area of Science:

• Exercise Physiology
• Biomedical Engineering
• Sports Science

Background:

• Muscle oxygenation is critical for exercise performance.
• Non-invasive monitoring of muscle oxygenation during dynamic exercise remains challenging.
• Understanding regional muscle metabolic responses is key to optimizing training.

Purpose of the Study:

• To evaluate the efficacy of spatially resolved near-infrared spectroscopy (SRS-NIRS) for assessing calf and thigh muscle oxygenation during running.
• To investigate the impact of different running protocols on muscle oxygenation and physiological responses.
• To explore the relationship between muscle oxygenation, mechanical efficiency, and exercise intensity.

Main Methods:

• Utilized a SRS-NIRS broadband system to measure total hemoglobin and oxygen saturation (SO2) in calf and thigh muscles.
• Employed two running protocols on a treadmill: incremental speed and a pacing paradigm (varying step frequency).
• Measured limb acceleration using hip-mounted accelerometers and physiological data via spirometry.

Main Results:

• Calf muscle demonstrated significantly greater desaturation compared to thigh muscle.
• Oxygen saturation (SO2) differed significantly between high and low step frequencies during the pacing protocol.
• Differences in VO2 at identical workloads indicated altered mechanical efficiency between pacing conditions.

Conclusions:

• SRS-NIRS is sensitive enough to detect small, meaningful changes in muscle oxygenation during dynamic exercise.
• The findings highlight regional differences in muscle oxygen utilization during running.
• Combined use of SRS-NIRS, spirometry, and accelerometry offers a comprehensive approach for metabolic exercise studies.