title: Dietary intake, serum hormones, muscle mass and strength during strength training in 49 - 73-year-old men.
abstract: Effects of dietary intake on serum hormones, muscle cross-sectional area (CSA) and strength during strength training were studied in two groups of men: 1) strength training + nutritional counseling (n = 22, 59.1 +/- 6.1 yrs), and 2) strength training (n = 23, 58.5 +/- 7.1 yrs). Both groups performed strength training twice a week for 21 weeks. Counseling increased carbohydrate (p < 0.01) and fiber intake (p < 0.001) and polyunsaturated/saturated fat-ratio (p < 0.05) and decreased fat intake (p < 0.01). Muscle strength and CSA increased by 16 - 20 % and by 5.4 - 5.9 % in both groups (p < 0.001). Changes in protein content of diet correlated with the changes in the acute postexercise concentrations of total (r = 0.64, p < 0.01) and free testosterone (r = 0.54, p < 0.05) after training in the counseling group. Moreover, changes in the free testosterone responses to heavy-resistance exercise correlated with the increases in the muscle CSA (r = 0.52, p < 0.05) in the counseling group. Serum basal testosterone/sex hormone-binding globulin-ratios correlated with the body mass normalized energy (kJ/kg: r = 0.54, p < 0.001), protein (g/kg: r = 0.42, p < 0.01) and fat (g/kg: r = 0.51, p < 0.01) intake in all participants during the training. The data indicate that protein and fat intake may influence serum testosterone concentrations and that the changes in exercise-induced testosterone responses may contribute to muscle mass development during strength training.
authors.affiliation: Department of Biology of Physical Activity and Neuromuscular Research Center, University of Jyväskylä, Jyväskylä, Finland. janne.sallinen@sport.jyu.fi
authors.forename: J
authors.initials: J
authors.lastname: Sallinen
authors.forename: A
authors.initials: A
authors.lastname: Pakarinen
authors.forename: M
authors.initials: M
authors.lastname: Fogelholm
authors.forename: M
authors.initials: M
authors.lastname: Alen
authors.forename: J S
authors.initials: JS
authors.lastname: Volek
authors.forename: W J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: K
authors.initials: K
authors.lastname: Häkkinen
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D003376:Counseling; D004032:Diet; D002149:Energy Intake; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D010806:Physical Education and Training; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000097:blood*
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D006854:Hydrocortisone