Changes in oxidative stress, inflammation and muscle damage markers following eccentric versus concentric cycling in...

To compare concentric and eccentric cycling performed by older adults for metabolic demand and post-exercise oxidative stress, inflammation and muscle damage.

Eight male and two female healthy older adults (60.4 ± 6.8 years) performed 30 min of moderate-intensity concentric (CONC-M: 50% maximum power output; PO_max) and eccentric cycling (ECC-M: 50% PO_max) and high-intensity eccentric cycling (ECC-H: 100% PO_max) in a randomized order. Average power output (PO), oxygen consumption (VO₂), heart rate (HR) and rate of perceived exertion were recorded during cycling. Some indirect markers of muscle damage were assessed before, and immediately, 24 and 48 h after cycling. Markers of oxidative stress (malondialdehyde: MDA, protein carbonyl), antioxidant (total antioxidant capacity, glutathione peroxidase activity: GPx) and inflammation (IL-6, TNF-α) were measured before and 5 min after cycling.

PO in ECC-H (202.6 ± 78.5 W) was > 50% greater (P < 0.05) than that of CONC-M (98.6 ± 33.1 W) and ECC-M (112.0 ± 42.1 W). VO₂ and HR were also greater (P < 0.05) for ECC-H than CONC-M (50% and 17%, respectively) and ECC-M (40% and 23%, respectively). Muscle strength loss at 1 day post-exercise (8-22%), peak soreness (10-62 mm) and creatine kinase activity (30-250 IU/L) after ECC-H were greater (P < 0.05) than those after ECC-M and CONC-M. MDA decreased (P < 0.05) after CONC-M (- 28%) and ECC-M (- 22%), but not after ECC-H. GPx activity increased after all exercises similarly (20-27%). IL-6 increased (P < 0.05) only after ECC-H (18%).

Oxidative stress was minimal after eccentric cycling, but high-intensity eccentric cycling induced moderate muscle damage and inflammation, which is not desirable for older individuals.