Relationships between decreasing force and muscle oxygenation kinetics during sustained static gripping

Area of Science:

• Exercise Physiology
• Biomedical Engineering
• Sports Science

Background:

• Sustained maximal static gripping (SSG) involves complex muscle physiological responses.
• Understanding muscle oxygenation kinetics during force reduction is crucial for performance analysis.
• Near-infrared spectroscopy (NIR) offers non-invasive insights into muscle oxygenation dynamics.

Purpose of the Study:

• To investigate muscle oxygenation kinetics (Oxy-Hb, Deoxy-Hb) during the decreasing force phase of SSG.
• To analyze these kinetics specifically around the inflection point of force decline.
• To correlate muscle oxygenation parameters with force-decreasing metrics.

Main Methods:

• Utilized near-infrared spectroscopy (NIR) to monitor muscle oxygenation (Oxy-Hb, Deoxy-Hb).
• Measured force output during sustained maximal static gripping (SSG) in 20 male adolescents (15-18 years).
• Analyzed time-to-lowest Oxy-Hb, time-to-highest Deoxy-Hb, and regression coefficients during force decline.

Main Results:

• Time to lowest Oxy-Hb correlated significantly with decreasing force times and rate of force decline (0-1 min).
• Time to highest Deoxy-Hb and its decreasing phase coefficient correlated with force decrement (1-2 min).
• The inflection point of gripping force aligns with the highest Deoxy-Hb, indicating blood flow resumption.

Conclusions:

• Muscle oxygenation kinetics, particularly Oxy-Hb and Deoxy-Hb dynamics, are closely linked to force reduction during SSG.
• NIR-derived parameters can quantify oxygenation deficiency and blood flow resumption during fatiguing contractions.
• Findings provide insights into the physiological mechanisms underlying muscle fatigue and force loss in adolescents.