A COMPARISON OF THE RECOVERY RESPONSES FOLLOWING ISOMETRIC AND VARIABLE RESISTANCE EXERCISE IN TRAINED MEN

INTRODUCTION: Despite isometric exercise performed at long muscle length (LML), short muscle length (SML) and variable resistance exercise (VAR) represent effective methods to achieve neuromuscular and morphological adaptations [1,2], no studies to date investigated the recovery responses of the pectoral muscles following these training methods. Thus, the aim of the present study was to compare acute effects, muscle damage and the recovery responses following LML, SML and VAR exercise sessions involving the pectoral muscles in resistance trained men. METHODS: Twelve trained men (age: 25.3 ± 4.1 years; height: 177.6 ± 7.3 cm; body mass: 81.6 ± 10.1; training experience: 6.7 ± 3.7; 1RM bench press: 108.5 ± 21.6 kg) performed a LML, SML and VAR exercise protocol in random order, with a 10-day washout between them. Participants were assessed prior to each protocol, 15 minutes (P-15min), 24 hours (P-24h) and 48 hours (P-48h) post-exercise for muscle architecture (muscle thickness [PECMT] and echo-intensity [PECEI]), and performance (peak isometric force [PF], power at bench press throw [BTP]) and muscle soreness. Blood samples were also collected at BL and at P-24h and Creatine Phosphokinase (CPK) was measured. RESULTS: A longer time to recover the initial PECMT (p = 0.003) was registered in VAR, compared to LML and SML. This parameter returned to baseline at P-48h following VAR, and in correspondence of P-24h following LML and SML protocols. Similar recovery responses between the protocols were detected for PECEI (p = 0.369), PF (p > 0.319), BPT (p = 0.614) and muscle soreness (p = 0.115). The PECEI, PF and BPT parameters returned to BL within 24 h following all the protocols while muscle soreness was still present at P-48h without differences between the protocols. In addition, all the exercise protocols resulted in similar (p = 0.727) elevations of CPK (382.64 ± 172.95). CONCLUSION: Results of the present investigation indicated that upper body isometric exercises performed at LML and SML and VAR exercise may result in muscle damage. The metabolic stimulus and the presence of eccentric phases in VAR protocol only, may have delayed the return to baseline registered for muscle architecture compared to both LML and SML protocols. A recovery period of 24-48h was required to dissipate performance reductions and partially muscle soreness following both isometric and VAR exercise protocols for the upper body muscles.