Muscle Oxygenation Threshold in More and Less Active Muscles and 3,000-m Running Pace

Area of Science:

• Exercise Physiology
• Sports Science
• Biomedical Engineering

Background:

• Muscle oxygenation thresholds are critical physiological markers.
• Understanding these thresholds in different muscle groups aids performance analysis.
• Near-infrared spectroscopy (NIRS) offers non-invasive monitoring.

Purpose of the Study:

• To compare the second muscle oxygenation threshold (MOT2) in the vastus lateralis (VL) and biceps brachii (BB) muscles.
• To investigate the correlation between MOT2 in these muscles and 3,000-m running performance.
• To analyze muscle oxygenation responses during a free-paced 3,000-m time trial in elite athletes.

Main Methods:

• Graded exercise test (GXT) to determine MOT2 using wearable NIRS.
• Measurement of tissue saturation index (TSI) breakpoints in VL and BB muscles.
• 3,000-m outdoor running time trial conducted 48 hours post-GXT.

Main Results:

• No significant difference was found between MOT2 velocity in BB (19.3±1.3 km/h) and VL (19.4±1.2 km/h).
• Significant correlations were observed between BB MOT2 and 3,000-m mean velocity (r=0.88) and VL MOT2 and 3,000-m mean velocity (r=0.86).
• Integrated muscle oxygenation responses were noted in both muscles during GXT and the 3,000-m run.

Conclusions:

• Maximal aerobic capacity, as indicated by MOT2 in different muscles, influences 3,000-m running performance.
• VL and BB muscles function in an integrated manner during graded exercise and sustained running efforts.
• NIRS-derived MOT2 provides valuable insights into the physiological demands of endurance running.