L-Citrulline Protects Skeletal Muscle Cells from Cachectic Stimuli through an iNOS-Dependent Mechanism.

Dietary L-citrulline is thought to modulate muscle protein turnover by increasing L-arginine availability. To date, the direct effects of increased L-citrulline concentrations in muscle have been completely neglected. Therefore, we determined the role of L-citrulline in regulating cell size during catabolic conditions by depriving mature C2C12 myotubes of growth factors (serum free; SF) or growth factors and nutrients (HEPES buffered saline; HBS).

Post-exercise protein synthesis rates are only marginally higher in type I compared with type II muscle fibres following resistance-type exercise.

We examined the effect of an acute bout of resistance exercise on fractional muscle protein synthesis rates in human type I and type II muscle fibres. After a standardised breakfast (31 ± 1 kJ kg(-1) body weight, consisting of 52 Energy% (En%) carbohydrate, 34 En% protein and 14 En% fat), 9 untrained men completed a lower-limb resistance exercise bout (8 sets of 10 repetitions leg press and leg extension at 70% 1RM). A primed, continuous infusion of L: -[ring-(13)C(6)]phenylalanine was combined with muscle biopsies collected from both legs immediately after exercise and after 6 h of post-exercise recovery.

Skeletal muscle hypertrophy following resistance training is accompanied by a fiber type-specific increase in satellite cell content in elderly men.

We determined muscle fiber type-specific hypertrophy and changes in satellite cell (SC) content following a 12-week resistance training program in 13 healthy, elderly men (72 +/- 2 years). Leg strength and body composition (dual-energy X-ray absorptiometry and computed tomography) were assessed, and muscle biopsy samples were collected. Leg strength increased 25%-30% after training (p < .

Protein supplementation before and after exercise does not further augment skeletal muscle hypertrophy after resistance training in elderly men.

Background: Considerable discrepancy exists in the literature on the proposed benefits of protein supplementation on the adaptive response of skeletal muscle to resistance-type exercise training in the elderly.

Objective: The objective was to assess the benefits of timed protein supplementation on the increase in muscle mass and strength during prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein.

Design: Healthy elderly men (n = 26) aged 72 +/- 2 y were randomly assigned to a progressive, 12-wk resistance-type exercise training program with (protein group) or without (placebo group) protein provided before and immediately after each exercise session (3 sessions/wk, 20 g protein/session).