Muscle Oxygenation, Performance, and Perceived Fatigability During Low-Intensity Isometric Exercise: Effects of...

Area of Science:

• Exercise Physiology
• Sports Science
• Rehabilitation Medicine

Background:

• Understanding muscle oxygenation and perceived exertion is crucial for optimizing exercise protocols.
• Sex-based differences in physiological responses to exercise require further investigation.
• Blood flow restriction (BFR) is a technique used to enhance training adaptations, but its effects on fatigability need clarification.

Purpose of the Study:

• To investigate the effects of different low-intensity isometric exercise modalities (RPE-Clamp, BFR, NON-BFR) and sex on muscle oxygen saturation (SmO2), perceived exertion, pain, performance fatigability, and time to task failure.
• To compare the physiological and performance outcomes between men and women under these exercise conditions.
• To determine if BFR exercise induces greater fatigability than non-BFR exercise at matched torque levels.

Main Methods:

• Fifteen healthy men and 15 women performed three isometric exercise conditions: RPE-Clamp (RPE=3), torque-matched BFR, and torque-matched NON-BFR.
• Muscle oxygen saturation (SmO2) was monitored using near-infrared spectroscopy.
• Performance fatigability (PF) was assessed by the change in maximal voluntary isometric contraction, and time to task failure (TTF) was recorded.

Main Results:

• No significant differences in TTF were observed across conditions or between sexes.
• SmO2 was highest in RPE-Clamp and lowest in BFR; men showed lower SmO2 than women during BFR task failure.
• Performance fatigability was greater in BFR and NON-BFR compared to RPE-Clamp, with men exhibiting greater PF than women in BFR and NON-BFR conditions.

Conclusions:

• BFR exercise with moderate cuff pressure did not induce greater fatigability than NON-BFR exercise.
• Sex-related differences in absolute target torque may influence fatigability.
• The RPE-Clamp condition presents a less fatiguing option potentially suitable for clinical and rehabilitation settings, though its training efficacy warrants further study.