Early Muscle Gene Expression Changes With Eccentric Exercise Associated With Peak Delayed Onset Muscle Soreness

Abstract

Testosterone (T) is responsible for the morphological adaptations resulting from systematic physical training and T deficiency is related to worsen the components of physical fitness with a marked effect on muscle mass. However, is still unkwon whether physical exercise can be an factor for maintaining muscle mass in T deficiency. PURPOSE: Evaluate whether Treadmill Interval Training (TIT) is efficient in maintaining muscle mass in castrated mice. METHODS: 14 adult (3-4 months) Swiss mice were separated in two groups, Sham (n=6) and gonadectomized (GDX, n=8). The GDX underwent bilateral orchiectomy while the Sham underwent a surgical trauma. After recovery mice were subjected to a 10-day treadmill familiarization step within 2 weeks, 5 days/wk, 25º inclination, having both session duration and speed progressively increased from 5 to 15 min and 5 to 10 m/min, respectively. Next a maximum exercise tests were carried out with an interval of 48h to assess the average maximum distance and speed reached (MSR). The test consisted of 5 min warm-up at 6m/min followed by incremental speed stages of 2 m/min every 2 min.Test were considered maximum when the mice were unable to, or refused to run even with mechanical stimulation. Then, the animals were submitted to a 4 weeks of an TIT, consisting of an initial warm-up at 5 m/min during 5min, then 10 bouts of 4 min with interspersed with 2 min of active rest 5 m/min. The training starts with an intensity of 55-65% MSR, with an increase of 10% each week reaching the intensity range of 85-95%. After the training mice were euthanized and the soleus and gastrocnemius muscles were collected and weighed. We compared muscle weight between groups using One-way ANOVA/Tukey (p≤0.05). Data are presented as mean±SEM. RESULTS: No difference was observed in the soleus and gastrocnemius mass between Sham and GDX groups. CONCLUSION: Our finds showed that the T deficiency did not change soleus and gastrocnemius mass of male mice submitted to TIT. Supported by FAP-DF.