title: The effect of exercise mode on the acute response of satellite cells in old men.
abstract: OBJECTIVE
  A dysregulation of satellite cells may contribute to the progressive loss of muscle mass that occurs with age; however, older adults retain the ability to activate and expand their satellite cell pool in response to exercise. The modality of exercise capable of inducing the greatest acute response is unknown. We sought to characterize the acute satellite cell response following different modes of exercise in older adults.
  
  
  METHODS
  Sedentary older men (n = 22; 67 ± 4 years; 27 ± 2.6 kg*m(-2) ) were randomly assigned to complete an acute bout of either resistance exercise, high-intensity interval exercise on a cycle ergometer or moderate-intensity aerobic exercise. Muscle biopsies were obtained before, 24 and 48 h following each exercise bout. The satellite cell response was analysed using immunofluorescent microscopy of muscle cross sections.
  
  
  RESULTS
  Satellite cell expansion associated with type I fibres was observed 24 and 48 h following resistance exercise only (P ˂ 0.05), while no expansion of type II-associated satellite cells was observed in any group. There was a greater number of activated satellite cells 24 h following resistance exercise (pre: 1.3 ± 0.1, 24 h: 4.8 ± 0.5 Pax7 + /MyoD+cells/100 fibres) and high-intensity interval exercise (pre: 0.7 ± 0.3, 24 h: 3.1 ± 0.3 Pax7 + /MyoD+cells/100 fibres) (P ˂ 0.05). The percentage of type I-associated SC co-expressing MSTN was reduced only in the RE group 24 h following exercise (pre: 87 ± 4, 24 h: 57 ± 5%MSTN+ type I SC) (P < 0.001).
  
  
  CONCLUSIONS
  Although resistance exercise is the most potent exercise type to induce satellite cell pool expansion, high-intensity interval exercise was also more potent than moderate-intensity aerobic exercise in inducing satellite cell activity.
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
authors.forename: J P
authors.initials: JP
authors.lastname: Nederveen
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Joanisse
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
authors.forename: C M L
authors.initials: CM
authors.lastname: Séguin
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
authors.forename: K E
authors.initials: KE
authors.lastname: Bell
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: S K
authors.initials: SK
authors.lastname: Baker
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
authors.forename: S M
authors.initials: SM
authors.lastname: Phillips
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada.|Department of Medical Physics & Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Parise
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D049109:Cell Proliferation / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055435:Myostatin / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism*
chemical_list: D055435:Myostatin
keywords: ageing; exercise; satellite cells