Recovery response comparisons between variable resistance and long and short muscle length isometric exercise

Area of Science:

• Exercise Physiology
• Muscle Adaptation
• Sports Science

Background:

• Isometric exercises at long muscle length (LML) and short muscle length (SML), and variable resistance (VAR) exercises, are established methods for inducing neuromuscular and morphological adaptations.
• Previous research has not directly compared the recovery of the pectoralis major muscle following these specific training modalities.

Purpose of the Study:

• To investigate and compare muscle damage and recovery of the pectoralis major in trained men after LML, SML, and VAR exercise protocols.

Main Methods:

• Twelve trained men participated in a randomized crossover study with a 10-day washout period between protocols.
• Muscle thickness (MT), echo intensity (EI), isometric peak force, bench press throw power (BPT), muscle soreness, and creatine phosphokinase (CPK) levels were assessed at baseline and at various time points post-exercise (15 min, 24 h, 48 h).

Main Results:

• Variable resistance (VAR) exercise led to more pronounced changes in muscle thickness (MT) at 15 min and 24 h post-exercise compared to SML and LML protocols.
• No significant differences were observed between protocols for echo intensity (EI), isometric peak force, bench press throw power (BPT), or muscle soreness.
• Muscle soreness persisted for 48 hours across all conditions, while EI, peak force, and BPT returned to baseline by 24 hours. Creatine phosphokinase (CPK) levels showed similar elevations across all protocols.

Conclusions:

• All three exercise protocols (LML, SML, VAR) induce muscle damage in trained individuals.
• Variable resistance (VAR) exercise may impose greater initial mechanical and metabolic stress, potentially leading to a longer recovery period for muscle architecture compared to LML and SML isometric exercises.