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Title: THE ALPHA-ACTININ-3 (ACTN3) R577X POLYMORPHISM INFLUENCES KNEE EXTENSOR PEAK POWER RESPONSE TO STRENGTH TRAINING IN OLDER ADULTS

Author
item DELMONICO, MATTHEW - UMD, COLLEGE PARK, KINES.
item KOSTEK, MATTHEW - UMD, COLLEGE PARK, KINES.
item DOLDO, NEIL - UMD, COLLEGE PARK, KINES.
item HAND, BRIAN - UMD, COLLEGE PARK, KINES.
item BAILEY, JASON - UMD, COLLEGE PARK, KINES.
item LANG, JESSE - UMD, COLLEGE PARK, KINES.
item WALSH, SEAN - UMD, COLLEGE PARK, KINES.
item Conway, Joan
item CARIGAN, CRAIG - UMD, COLLEGE PARK, AERO.
item ROTH, STEPHEN - UMD, COLLEGE PARK, KINES.
item HURLEY, BEN - UMD, COLLEGE PARK, KINES.

Submitted to: Journal of Gerontology Medical Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2006
Publication Date: 2/1/2007
Citation: Delmonico, M.J., Kostek, M.C., Doldo, N.A., Hand, B.D., Walsh, S., Conway, J.M., Carignan, C.R., Roth, S.M., Hurley, B.F. 2007. Alpha-actinin-3 (ACTN3) R577X polymorphism influences knee extensor peak power response to strength training in older men and women. Journal of Gerontology A: Biological Sciences and Medical Sciences. 62(2):206-212.

Interpretive Summary: It is known that muscle size, strength and power can decrease with age. These changes in muscle can have serious health and quality of life consequences in the aging population. One of the genetic markers for muscle power (the ACTN3 R577X polymorphism) has been associated with muscle power performance in cross-sectional studies among aging adults. We studied the effect of strength training on the ability of the muscle to resist a known weight, which is called peak power (PP), in 71 older men and 86 older women. At baseline, women who had two copies of this gene (XX) had higher peak power than the other genotypes in whom the gene was absent (RR) or those who had only one copy of the gene (RX). In men and women who had no copies of the gene, the response to strength training was greater than in those who had two copies of the gene. The results indicate that this genetic characteristic (the ACTN3 R577X polymorphism) influences the response of quadriceps muscle power to strength training in older adults. These findings contribute to the understanding of the causes for variation in response to strength training in older adults and will have impact on the design of exercise strength training regimens for older men and women and are of interest to health professionals, physical therapists, and exercise physiologists.

Technical Abstract: The ACTN3 R577X polymorphism has been associated with muscle power performance in cross-sectional studies. We examined baseline knee extensor concentric peak power (PP) and PP change with 10 weeks of unilateral knee extensor strength training (ST) using pneumatic resistance machines in 71 older men (mean =65, SD=8 years) and 86 older women (mean = 64, SD=9 years). At baseline, XX women had an absolute (same resistance) and relative PP (70% of 1 RM) that was higher than the RR and RX groups (P less than 0.05). In men, absolute PP change with ST in the RR (n=16) group tended to be higher than the XX group (n=9; P=0.07). In women, relative PP change with ST in the RR group (n=16) was higher than the XX group (n=17; P less than 0.05). The results indicate that the ACTN3 R577X polymorphism influences the response of quadriceps muscle power to ST in older adults.