title: Resistance training and pioglitazone lead to improvements in muscle power during voluntary weight loss in older adults.
abstract: BACKGROUND
  The prevalence of obesity in older adults is increasing but concerns exist about the effect of weight loss on muscle function. Demonstrating that muscle strength and power are not adversely affected during "intentional" weight loss in older adults is important given the wide-ranging negative health effects of excess adiposity.
  
  
  METHODS
  Participants (N = 88; age = 70.6 ± 3.6 years; body mass index = 32.8 ± 4.5 kg/m(2)) were randomly assigned to one of four intervention groups: pioglitazone or placebo and resistance training (RT) or no RT, while undergoing intentional weight loss via a hypocaloric diet. Outcomes were leg press power and isometric knee extensor strength. Analysis of covariance, controlling for baseline values, compared follow-up means of power and strength according to randomized groups.
  
  
  RESULTS
  Participants lost an average of 6.6% of initial body mass, and significant declines were observed in fat mass, lean body mass, and appendicular lean body mass. Compared with women not randomized to RT, women randomized to RT had significant improvements in leg press power (p < .001) but not in knee extensor strength (p = 0.12). No significant differences between groups in change in power or strength from baseline were detected in men (both p > .25). A significant pioglitazone-by-RT interaction for leg press power was detected in women (p = .006) but not in men (p = .88).
  
  
  CONCLUSIONS
  In older overweight and obese adults, a hypocaloric weight loss intervention led to significant declines in lean body mass and appendicular lean body mass. However, in women assigned to RT, leg power significantly improved following the intervention, and muscle strength or power was not adversely effected in the other groups. Pioglitazone potentiated the effect of RT on muscle power in women but not in men; mechanisms underlying this sex effect remain to be determined.
authors.affiliation: Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC 27109-7868, USA. marshap@wfu.edu
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Marsh
authors.forename: M Kyla
authors.initials: MK
authors.lastname: Shea
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Vance Locke
authors.forename: Michael E
authors.initials: ME
authors.lastname: Miller
authors.forename: Scott
authors.initials: S
authors.lastname: Isom
authors.forename: Gary D
authors.initials: GD
authors.lastname: Miller
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Nicklas
authors.forename: Mary F
authors.initials: MF
authors.lastname: Lyles
authors.forename: Jeffery J
authors.initials: JJ
authors.lastname: Carr
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
mesh_terms: D000368:Aged; D000375:Aging; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D008297:Male; D053580:Muscle Strength; D009765:Obesity / Q000453:epidemiology / Q000628:therapy*; D050177:Overweight / Q000628:therapy; D000077205:Pioglitazone; D055070:Resistance Training / Q000379:methods; D016037:Single-Blind Method; D045162:Thiazolidinediones / Q000008:administration & dosage*; D016896:Treatment Outcome; D015431:Weight Loss
chemical_list: D007004:Hypoglycemic Agents; D045162:Thiazolidinediones; D000077205:Pioglitazone
keywords: Muscle power; Muscle strength; Obesity; Resistance training; Voluntary weight loss.