title: The effect of resistance training combined with timed ingestion of protein on muscle fiber size and muscle strength.
abstract: Acute muscle protein metabolism is modulated not only by resistance exercise but also by amino acids. However, less is known about the long-term hypertrophic effect of protein supplementation in combination with resistance training. The present study was designed to compare the effect of 14 weeks of resistance training combined with timed ingestion of isoenergetic protein vs carbohydrate supplementation on muscle fiber hypertrophy and mechanical muscle performance. Supplementation was administered before and immediately after each training bout and, in addition, in the morning on nontraining days. Muscle biopsy specimens were obtained from the vastus lateralis muscle and analyzed for muscle fiber cross-sectional area. Squat jump and countermovement jump were performed on a force platform to determine vertical jump height. Peak torque during slow (30 degrees s-1) and fast (240 degrees s-1) concentric and eccentric contractions of the knee extensor muscle was measured in an isokinetic dynamometer. After 14 weeks of resistance training, the protein group showed hypertrophy of type I (18% +/- 5%; P < .01) and type II (26% +/- 5%; P < .01) muscle fibers, whereas no change above baseline occurred in the carbohydrate group. Squat jump height increased only in the protein group, whereas countermovement jump height and peak torque during slow isokinetic muscle contraction increased similarly in both groups. In conclusion, a minor advantage of protein supplementation over carbohydrate supplementation during resistance training on mechanical muscle function was found. However, the present results may have relevance for individuals who are particularly interested in gaining muscle size.
authors.affiliation: Sports Medicine Research, Unit/Team Denmark Test Center, Bispebjerg Hospital, DK-2400 Copenhagen, Denmark. LL_andersen@hotmail.com
authors.forename: Lars L
authors.initials: LL
authors.lastname: Andersen
authors.forename: Goran
authors.initials: G
authors.lastname: Tufekovic
authors.forename: Mette K
authors.initials: MK
authors.lastname: Zebis
authors.forename: Regina M
authors.initials: RM
authors.lastname: Crameri
authors.forename: George
authors.initials: G
authors.lastname: Verlaan
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
authors.forename: Charlotte
authors.initials: C
authors.lastname: Suetta
authors.forename: Peter
authors.initials: P
authors.lastname: Magnusson
authors.forename: Per
authors.initials: P
authors.lastname: Aagaard
mesh_terms: D000328:Adult; D048429:Cell Size / Q000187:drug effects; D004040:Dietary Carbohydrates / Q000494:pharmacology; D004044:Dietary Proteins / Q000494:pharmacology*; D019587:Dietary Supplements; D004435:Eating / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D009929:Organ Size / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D013177:Sports / Q000502:physiology; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins