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Gender-specific neuromuscular adaptations to unloading in isolated rat soleus muscles
Michael R Deschenes1,2, Colleen M Leathrum1
1Department of Kinesiology & Health Sciences, College of William & Mary, Williamsburg, Virginia, 23187-8795, USA.
Introduction:
The potential of gender to affect unloading-induced neuromuscular adaptations was investigated.
Methods:
Twenty male and 20 female rats were assigned to control (CTL), or unloaded (UL) conditions. After 2 weeks of unloading, soleus muscles were removed, and neuromuscular function was assessed during a train of alternating indirect (neural) and direct (muscle) stimuli.
Results:
In rested muscle, strength showed significant (P ≤ 0.05) main effects for gender (male > female) and treatment (CTL > UL). By the end of the testing protocol, when muscles showed fatigue, gender-related and treatment-related differences in strength had disappeared. Neuromuscular transmission efficiency and strength suffered a greater decline during the testing protocol in males than females. Unloaded male muscles displayed greater contractile velocity than female muscles both when rested and fatigued.
Conclusions:
Gender affected unloading-induced neuromuscular adaptations. The greater strength of rested male muscles was due to greater muscle mass and neuromuscular transmission efficiency. Muscle Nerve 54: 300-307, 2016.
