Neuromuscular function following muscular unloading and blood flow restricted exercise

Area of Science:

• Neuromuscular Physiology
• Exercise Science
• Rehabilitation Medicine

Background:

• Unilateral lower limb suspension (ULLS) is a model for unloading, inducing muscle atrophy and neuromuscular dysfunction.
• Understanding the impact of unloading on both central and peripheral neuromuscular function is crucial for developing effective countermeasures.

Purpose of the Study:

• To evaluate central and peripheral neuromuscular function in knee extensors (KE) and plantar flexors (PF) after 30 days of ULLS.
• To examine the effects of low-load blood flow restricted (BFR) resistance training on the KE during ULLS.

Main Methods:

• Assessed strength, cross-sectional area (CSA), central activation, evoked force, and rates of force development/relaxation in KE and PF before and after ULLS.
• Eight subjects underwent BFR resistance training on the KE three times per week during ULLS (ULLS + Exercise).

Main Results:

• ULLS led to significant decrements in KE and PF strength and CSA.
• ULLS + Exercise maintained KE strength and CSA but not PF.
• KE central activation declined in ULLS but was maintained in ULLS + Exercise; however, no significant time × group interaction was found. PF central activation reduced in both groups.

Conclusions:

• ULLS compromises central and peripheral neuromuscular function.
• BFR resistance training during ULLS can preserve muscle mass and strength in trained muscles (KE).
• BFR training may only partially mitigate neuromuscular dysfunction induced by unloading.