title: There Are No Nonresponders to Resistance-Type Exercise Training in Older Men and Women.
abstract: OBJECTIVE
  To assess the proposed prevalence of unresponsiveness of older men and women to augment lean body mass, muscle fiber size, muscle strength, and/or physical function following prolonged resistance-type exercise training.
  
  
  METHODS
  A retrospective analysis of the adaptive response to 12 (n = 110) and 24 (n = 85) weeks of supervised resistance-type exercise training in older (>65 years) men and women.
  
  
  METHODS
  Lean body mass (DXA), type I and type II muscle fiber size (biopsy), leg strength (1-RM on leg press and leg extension), and physical function (chair-rise time) were assessed at baseline, and after 12 and 24 weeks of resistance-type exercise training.
  
  
  RESULTS
  Lean body mass increased by 0.9 ± 0.1 kg (range: -3.3 to +5.4 kg; P < .001) from 0 to 12 weeks of training. From 0 to 24 weeks, lean body mass increased by 1.1 ± 0.2 kg (range: -1.8 to +9.2 kg; P < .001). Type I and II muscle fiber size increased by 324 ± 137 μm(2) (range: -4458 to +3386 μm(2); P = .021), and 701 ± 137 μm(2) (range: -4041 to +3904 μm(2); P < .001) from 0 to 12 weeks. From 0 to 24 weeks, type I and II muscle fiber size increased by 360 ± 157 μm(2) (range: -3531 to +3426 μm(2); P = .026) and 779 ± 161 μm(2) (range: -2728 to +3815 μm(2); P < .001). The 1-RM strength on the leg press and leg extension increased by 33 ± 2 kg (range: -36 to +87 kg; P < .001) and 20 ± 1 kg (range: -22 to +56 kg; P < .001) from 0 to 12 weeks. From 0 to 24 weeks, leg press and leg extension 1-RM increased by 50 ± 3 kg (range: -28 to +145 kg; P < .001) and 29 ± 2 kg (range: -19 to +60 kg; P < .001). Chair-rise time decreased by 1.3 ± 0.4 seconds (range: +21.6 to -12.5 seconds; P = .003) from 0 to 12 weeks. From 0 to 24 weeks, chair-rise time decreased by 2.3 ± 0.4 seconds (range: +10.5 to -23.0 seconds; P < .001). Nonresponsiveness was not apparent in any subject, as a positive adaptive response on at least one training outcome was apparent in every subject.
  
  
  CONCLUSIONS
  A large heterogeneity was apparent in the adaptive response to prolonged resistance-type exercise training when changes in lean body mass, muscle fiber size, strength, and physical function were assessed in older men and women. The level of responsiveness was strongly affected by the duration of the exercise intervention, with more positive responses following more prolonged exercise training. We conclude that there are no nonresponders to the benefits of resistance-type exercise training on lean body mass, fiber size, strength, or function in the older population. Consequently, resistance-type exercise should be promoted without restriction to support healthy aging in the older population.
authors.affiliation: Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands; Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Tyler A
authors.initials: TA
authors.lastname: Churchward-Venne
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands; Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Michael
authors.initials: M
authors.lastname: Tieland
authors.affiliation: Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands; Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Lex B
authors.initials: LB
authors.lastname: Verdijk
authors.affiliation: Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands; Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Marika
authors.initials: M
authors.lastname: Leenders
authors.affiliation: Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands.
authors.forename: Marlou L
authors.initials: ML
authors.lastname: Dirks
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands; Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Lisette C P G M
authors.initials: LC
authors.lastname: de Groot
authors.affiliation: Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands; Top Institute Food and Nutrition, Wageningen, The Netherlands. Electronic address: L.vanLoon@maastrichtuniversity.nl.
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D015577:Geriatric Assessment / Q000379:methods; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D011597:Psychomotor Performance; D055070:Resistance Training / Q000379:methods*; D012189:Retrospective Studies
keywords: Resistance exercise; aging; lean body mass; muscle function; muscle strength; sarcopenia