title: Four-month course of soluble milk proteins interacts with exercise to improve muscle strength and delay fatigue in elderly participants.
abstract: BACKGROUND
  The benefit of protein supplementation on the adaptive response of muscle to exercise training in older people is controversial.
  
  
  OBJECTIVE
  To investigate the independent and combined effects of a multicomponent exercise program with and without a milk-based nutritional supplement on muscle strength and mass, lower-extremity fatigue, and metabolic markers.
  
  
  METHODS
  A sample of 48 healthy sedentary men aged 60.8 ± 0.4 years were randomly assigned to a 16-week multicomponent exercise training program with a milk-based supplement containing, besides proteins [total milk proteins 4 or 10 g/day or soluble milk proteins rich in leucine (PRO) 10 g/day], carbohydrates and fat. Body composition, muscle mass and strength, and time to task failure, an index of muscle fatigue, were measured. Blood lipid, fibrinogen, creatine phosphokinase, glucose, insulin, C-reactive protein, interleukin-6, tumor necrosis factor-α soluble receptors, and endothelial markers were assessed.
  
  
  RESULTS
  Body fat mass was reduced after the 4-month training program in groups receiving 10 g/day of protein supplementation (P < .01). The training program sustained with the daily 10 g/day PRO was associated with a significant increase in dominant fat free mass (+5.4%, P < .01) and in appendicular muscle mass (+4.5%, P < .01). Blood cholesterol was decreased in the trained group receiving 10 g/day PRO. The index of insulin resistance (homeostasis model assessment-insulin resistance) and blood creatine phosphokinase were reduced in the groups receiving 10 g/day PRO, irrespective of exercise. The inflammatory and endothelial markers were not different between the groups. Training caused a significant improvement (+10.6% to 19.4%, P < .01) in the maximal oxygen uptake. Increased maximum voluntary contraction force was seen in the trained groups receiving 10 g/day of proteins (about 3%, P < .05). Time to task failure was improved in the trained participants receiving a 10 g/day supplementation with PRO (P < .01).
  
  
  CONCLUSIONS
  Soluble milk proteins rich in leucine improved time to muscle failure and increase in skeletal muscle mass and strength after prolonged multicomponent exercise training in healthy older men.
authors.affiliation: INRA, UMR1019, UNH, CRNH Auvergne, F-63000 Clermont-Ferrand, France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine, BP 10448, F-63000 Clermont-Ferrand, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Gryson
authors.affiliation: Clermont Université, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171 Aubière Cedex, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Ratel
authors.affiliation: Clermont Université, Université Blaise Pascal, EA 3533, Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques (AME2P), BP 80026, F-63171 Aubière Cedex, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Rance
authors.affiliation: Department of Sport Medicine and Functional Explorations, University Hospital (CHU) Clermont-Ferrand, Hospital Gabriel-Montpied, Clermont-Ferrand, F-63003 France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Penando
authors.affiliation: Lactalis Nutrition Santé, Torcé, F-35370, France; Lactalis Research and Development, Retiers, F-35000/240, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Bonhomme
authors.affiliation: Lactalis Research and Development, Retiers, F-35000/240, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Le Ruyet
authors.affiliation: Department of Sport Medicine and Functional Explorations, University Hospital (CHU) Clermont-Ferrand, Hospital Gabriel-Montpied, Clermont-Ferrand, F-63003 France.
authors.forename: Martine
authors.initials: M
authors.lastname: Duclos
authors.affiliation: INRA, UMR1019, UNH, CRNH Auvergne, F-63000 Clermont-Ferrand, France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine, BP 10448, F-63000 Clermont-Ferrand, France; Clinical Nutrition Department, CHU Clermont-Ferrand, Clermont-Ferrand, F-63003, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Boirie
authors.affiliation: INRA, UMR1019, UNH, CRNH Auvergne, F-63000 Clermont-Ferrand, France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine, BP 10448, F-63000 Clermont-Ferrand, France. Electronic address: swalrand@clermont.inra.fr.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Walrand
mesh_terms: D015415:Biomarkers / Q000097:blood; D001823:Body Composition / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology / Q000517:prevention & control*; D006801:Humans; D007930:Leucine / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D008894:Milk Proteins / Q000008:administration & dosage*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D008894:Milk Proteins; D007930:Leucine
keywords: Soluble milk proteins rich in leucine; exercise; muscle fatigue; muscle strength; older people