Impact of differing eccentric-concentric phase durations on muscle damage and anabolic hormones

Abstract

BACKGROUND: Resistance exercises are widely used to enhance muscle hypertrophy. Hypertrophy occurs with effect of mechanical loading, metabolic stress, and muscle damage. The time under tension in eccentric, isometric, and concentric phases of resistance exercises can alter muscle damage and anabolic hormone responses. OBJECTIVES: The aim of the study was to reveal the effect of the time spent in the concentric and eccentric phases of the movement on muscle damage and anabolic hormone response during resistance exercise. METHODS: Ten male subjects participated in the study. A, B, C tempo protocols were created by changing the time under tension to be 1 or 2 seconds in the eccentric and concentric phases of bench press and squat movements. In all protocols, isometric phases were 0 sec. The metronome was used to apply tempos. Blood samples were taken before each protocol, after administration, and in the 24th, 48th and 72nd hours after exercise; and serum insulin, testosterone, Insuline-like Growth Factor-1 (IGF-1), Creatine Kinase (CK) and Lactate Dehydrogenase (LDH) levels were evaluated. RESULTS: Time-wise changes in CK were statistically different for all protocols (p< 0.05). CK levels in the 24th hour of the protocol C and the 48th hour of the protocol B were significantly higher than those in the other protocols (p< 0.05). IGF-1 and testosterone levels were significantly higher in the protocol B in the post-test, compared to the other protocols (p< 0.05). Insulin levels in the 24t⁢h hour were significantly higher in the protocol B compared to those in others (p< 0.05). Time-wise changes in LDH parameters were not statistically significant in any hours (p> 0.05). CONCLUSIONS: Extending time under tension in the eccentric phase of a bout of resistance exercise appears to affect the anabolic hormone response and muscle damage. In this way, increased metabolic response and mechanical stress can induce muscle mass gain.