Effect of eccentric versus concentric exercise training on mitochondrial function.

Area of Science:

• Exercise physiology
• Skeletal muscle metabolism

Background:

• The impact of eccentric (ECC) versus concentric (CON) muscle training on metabolic properties remains unclear.
• This study investigated oxidative capacity and mitochondrial hydrogen peroxide (H2 O2) production following ECC and CON training at matched power outputs.

Purpose of the Study:

• To compare the effects of ECC and CON training on skeletal muscle oxidative capacity.
• To assess mitochondrial H2 O2 production and skeletal muscle damage after ECC and CON training.

Main Methods:

• Forty-eight rats underwent 5- or 20-day ECC or CON training regimens.
• Assessed mitochondrial respiration, H2 O2 production, citrate synthase activity (CS), and muscle damage in gastrocnemius (GAS), soleus (SOL), and vastus intermedius (VI) muscles.

Main Results:

• Maximal mitochondrial respiration improved only in GAS and SOL after 20 days of CON training.
• Mitochondrial H2 O2 production increased in VI exclusively after 20 days of ECC training.
• Transient skeletal muscle damage was observed in VI following 5 days of ECC training.

Conclusions:

• Twenty days of ECC or CON training at similar mechanical power did not enhance skeletal muscle oxidative capacities.
• ECC training elevated mitochondrial H2 O2 production in the VI muscle, potentially due to transient muscle damage.