Muscle Swelling and Neuromuscular Responses Following Blood Flow Restricted Exercise in Untrained Women

Area of Science:

• Exercise Physiology
• Sports Science
• Muscle Physiology

Background:

• Conflicting evidence exists regarding exercise-induced muscle damage (EIMD) following blood flow restriction (BFR) training protocols.
• Two common BFR protocols are 75 total repetitions (BFR-75) and training to volitional failure (BFR-F).

Purpose of the Study:

• To investigate and compare muscle swelling, peak torque, and neuromuscular responses after BFR-75 and BFR-F protocols.
• To clarify the extent of EIMD caused by different BFR training intensities.

Main Methods:

• Thirteen untrained women performed unilateral isokinetic leg extensions using BFR-75 and BFR-F protocols.
• Muscle swelling was assessed via ultrasound (thickness, cross-sectional area, echo intensity) at multiple time points post-exercise.
• Peak torque and surface electromyography (sEMG) were measured to evaluate neuromuscular responses.

Main Results:

• No significant differences in muscle swelling, peak torque, or neuromuscular responses were observed between the BFR-75 and BFR-F conditions.
• Both protocols induced an acute increase in muscle thickness and cross-sectional area, which returned to baseline within 24 hours.
• No changes in echo intensity, sEMG amplitude, sEMG frequency, or neuromuscular efficiency were detected. Peak torque increased post-exercise.

Conclusions:

• Neither the BFR-75 nor the BFR-F protocol induced exercise-induced muscle damage in untrained women.
• Both BFR protocols resulted in transient muscle swelling that resolved within 24 hours post-exercise.
• These findings suggest that BFR training, within these parameters, is safe and does not lead to significant muscle damage.