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Title: ADRENERGIC RECEPTOR GENOTYPE INFLUENCES THE EFFECTS OF STRENGTH TRAINING ON MID-THIGH INTER-MUSCULAR FAT

Author
item YAO, LILI - UNIV OF MD, COLLEGE PARK
item DELMONICO, MATTHEW - UNIV OF MD, COLLEGE PARK
item ROTH, STEPHEN - UNIV OF MD, COLLEGE PARK
item HAND, BRIAN - UNIV OF MD, COLLEGE PARK
item JOHNS, JOSHUA - UNIV OF MD, COLLEGE PARK
item CONWAY, JOAN
item DOUGLASS, LARRY - UNIV OF MD, COLLEGE PARK
item HURLEY, BEN - UNIV OF MD, COLLEGE PARK

Submitted to: Journal of Gerontology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2006
Publication Date: 6/1/2007
Citation: Yao, L., Delmonico, M., Roth, S., Hand, B., Johns, J., Conway, J.M., Douglass, L., Hurley, B. 2007. Adrenergic receptor genotype influences the effects of strength training on mid-thigh inter-muscular fat. Journal of Gerontology A: Biological Sciences and Medical Sciences. 62A (6):658-663.

Interpretive Summary: Intermuscular fat (IMF) can have significant effects on health in the elderly; therefore it is important to determine if specific forms of exercise can reduce IMF. Currently there is little information regarding the effects of strength training (ST) on (IMF) in this population. In addition, response to exercise training is known to be dependent on a person’s genetics. This study was conducted in 98 healthy and sedentary men and women from 50-85 years of age and tested the relationships among strength training, genetics, and IMF. One particular receptor, called the adrenergic receptor (ADR), has been implicated in ability of a person to reduce IMF following ST in younger populations. Mid-thigh IMF and muscle area were measured by computed tomography (CT) before and after 10 weeks of single leg ST in both the trained and untrained (control) legs. The ST program resulted in a substantial increase in thigh muscle strength and muscle area, but no significant changes in IMF in the whole group. However, IMF was significantly reduced with ST in subjects carrying the adrenergic receptor gene, but no significant change was observed with the noncarriers. The presence or absence of this genetically controlled receptor could predict the effectiveness of strength training in an individual. These data would be useful to health care providers, including exercise physiologists, physical therapists, and physicians, who design exercise programs for the elderly.

Technical Abstract: There is little information regarding the effects of strength training (ST) on intermuscular fat (IMF), which can have adverse effects on health status in the elderly. Regional fat alterations resulting from exercise interventions may be influenced by adrenergic receptor (ADR) Beta2 Gln27Glu and ADR alpha2b Glu12/Glu9 gene polymorphisms. Mid-thigh IMF and muscle area were measured by computed tomography (CT) before and after 10 weeks of single leg strength training (ST) in healthy, sedentary middle-aged and older (50 – 83 years) men (n = 46) and women (n = 52) in both their trained and untrained (control) legs. The ST program resulted in a substantial increase in one-repetition maximum (1-RM) strength (P less than 0.001) and muscle area (P less than 0.001), but no significant changes in IMF in the whole group. However, IMF was significantly reduced with ST in subjects carrying ADR beta2 Glu27 (-2. 3 cm squared, P = 0. 028), but no significant change was observed with Glu27 noncarriers. The decrease in IMF in ADR alpha2b Glu9 carriers (-1. 9 cm squared, P = 0. 066) was significantly different (-2. 9 cm squared, P = 0. 043) from a nonsignificant increase in Glu9 noncarriers. Glu27 carriers who also carried ADR alpha2b Glu9 significantly lost IMF with ST (-3. 8 cm2, P = 0. 018). The response of IMF to ST is influenced by ADR beta2 Gln27Glu and ADR alpha2b Glu12/Glu9 polymorphisms.