A contralateral repeated bout effect attenuates induction of NF-κB DNA binding following eccentric exercise.
We investigated the existence of contralateral repeated bout effect and tested if the attenuation of nuclear factor-kappa B (NF-κB; an important regulator of muscle inflammation) induction following eccentric exercise is a potential mechanism. Thirty-one healthy men performed two bouts of knee extension eccentric exercise, initially with one leg and then with the opposite leg 4 wk later. Vastus lateralis muscle biopsies of both exercised and control legs were taken 3 h postexercise. Knee extension isometric and isokinetic strength (60°/sec and 180°/sec) were measured at baseline, pre-exercise, immediately postexercise, and 1/day for 5 days postexercise. Serum creatine kinase (CK) activity and muscle soreness were assessed at baseline and 1/day for 5 days postexercise. NF-κB (p65) DNA-binding activity was measured in the muscle biopsies. Isometric strength loss was lower in bout 2 than in bout 1 at 24, 72, and 96 h postexercise (P < 0.05). Isokinetic strength (60°/s and 180°/s) was reduced less in bout 2 than in bout 1 at 72 h postexercise (P < 0.01). There were no significant differences between bouts for postexercise CK activity or muscle soreness. p65 DNA-binding activity was increased following eccentric exercise (compared with the control leg) in bout 1 (122.9% ± 2.6%; P < 0.001) and bout 2 (109.1% ± 3.0%; P < 0.05). Compared with bout 1, the increase in NF-κB DNA-binding activity postexercise was attenuated after bout 2 (P = 0.0008). Repeated eccentric exercise results in a contralateral repeated bout effect, which could be due to the attenuated increase in NF-κB activity postexercise.
Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts; and lxin@kin.umass.edu.
Ling
L
Xin
Department of Exercise Sciences, Brigham Young University, Provo, Utah.
Robert D
RD
Hyldahl
Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts; and.
Stuart R
SR
Chipkin
Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts; and.
Priscilla M
PM
Clarkson
D000328:Adult; D004247:DNA / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D015444:Exercise; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D005082:Physical Exertion; D011485:Protein Binding / Q000502:physiology
D016328:NF-kappa B; D004247:DNA
NF-κB; eccentric exercise; inflammatory response; muscle damage