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Reduced Scattering Coefficient During Incremental Exercise Is Constant Without Being Affected by Changes in Muscle
Tasuki Endo1, Ryotaro Kime2, Sayuri Fuse1
1Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo, Japan.
Advances in Experimental Medicine and Biology
|May 9, 2021
Summary
During ramp-incremental exercise, significant changes in deoxygenated hemoglobin and myoglobin and total hemoglobin and myoglobin occur. However, these physiological changes do not affect the reduced scattering coefficient in the vastus lateralis muscle.
Area of Science:
- Exercise Physiology
- Biophotonics
- Muscle Physiology
Background:
- Reduced scattering coefficient (μs') in vastus lateralis is known to change during exercise.
- These changes are attributed to blood volume fluctuations and metabolic byproduct accumulation.
- The specific impact of deoxygenation and blood volume shifts on μs' dynamics across varying aerobic capacities remains unclear.
Purpose of the Study:
- To investigate the influence of exercise-induced deoxygenation and blood volume changes on μs' dynamics.
- To compare these effects between individuals with lower and higher aerobic capacities during ramp-incremental exercise.
Main Methods:
- Twenty-three healthy young men performed ramp-incremental cycling to exhaustion.
- Participants were categorized into lower (Low) and higher (High) aerobic capacity groups based on VO2peak.
- Time-resolved near-infrared spectroscopy (NIRS) monitored deoxygenated hemoglobin and myoglobin (deoxy[Hb+Mb]), total hemoglobin and myoglobin (total[Hb+Mb]), and μs' in the vastus lateralis.
Main Results:
- Deoxy[Hb+Mb] and total[Hb+Mb] significantly increased with exercise intensity in both groups.
- Peak amplitudes showed a 106.4% increase for deoxy[Hb+Mb] and 17.9% for total[Hb+Mb] from baseline.
- No significant changes in μs' were observed during exercise, nor were there differences between the Low and High aerobic capacity groups.
Conclusions:
- Despite substantial deoxygenation and blood volume changes in the vastus lateralis during incremental exercise, μs' dynamics remain largely unaffected.
- Aerobic capacity does not appear to influence the relationship between these physiological changes and μs'.
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