Effects of higher habitual protein intake on resistance-training-induced changes in body composition and muscular strength in untrained older women: A clinical trial study.

BACKGROUND: Aging is accompanied by progressive and accentuated decline in muscular strength and skeletal muscle mass, affecting health and functional autonomy. Both resistance training (RT) and diet are strategies that may contribute to improvement in the health of the elderly. AIM: The purpose of this study was to evaluate the effects of higher habitual protein intake on RT-induced changes in body composition and strength in untrained postmenopausal women. METHODS: Seventy older women were submitted to an RT program. Body composition, muscular strength, and dietary intake (24 h dietary recall) were performed pre- and post-intervention. To verify different intervention effects according to protein intake of the participants, the sample was separated into tertiles according to protein intake: low, moderate, and high protein intake. RESULTS: A time vs. group interaction ( p < 0.05) was observed, with high protein intake presenting greater increases compared with low protein intake, for skeletal muscle mass (5.3% vs. 1.3%), lower limb lean soft tissue (4.9% vs. 1.4%), upper lean soft tissue (4.9% vs. 1.2%), preacher curl (24% vs. 15.2%), and total strength (16.4% vs. 11.7%). A time vs. group interaction ( p < 0.05) was observed, with high protein intake presenting greater increases compared with moderate protein intake, for skeletal muscle mass (5.3% vs. 3.2%). In all groups, a main effect of time ( p < 0.05) was observed for knee extension and chest press. CONCLUSIONS: We conclude that intake of >1.0 g/kg/day of protein promotes gains in skeletal muscle mass and muscular strength after RT in untrained older women.

Creatine supplementation elicits greater muscle hypertrophy in upper than lower limbs and trunk in resistance-trained men.

BACKGROUND: Creatine (Cr) supplementation associated with resistance training produces greater muscular strength improvements in the upper compared with the lower body; however, no study has investigated if such region-specific results are seen with gains in muscle mass. AIM: We aimed to evaluate the effect of Cr supplementation in combination with resistance training on lean soft tissue changes in the upper and lower limbs and trunk in resistance-trained young adult men. METHODS: In a randomized, double-blind and placebo-controlled design, 43 resistance-trained men (22.7 ± 3.0 years, 72.9 ± 8.7 kg, 177.9 ± 5.7 cm, 23.0 ± 2.5 kg/m2) received either creatine (Cr, n = 22) or placebo (PLA, n = 21) over an 8-week study period. The supplementation protocol included a loading phase (7 days, four doses of 0.3 g/kg per day) and a maintenance phase (7 weeks, single dose of 0.03 g/kg per day). During the same period, subjects performed resistance training four times per week using the following two-way split routine: Monday and Thursday = pectoral, shoulders, triceps, and abdomen, Tuesday and Friday = back, biceps, thighs, and calves. Lean soft tissue of the upper limbs (ULLST), lower limbs (LLLST), and trunk (TLST) was assessed by dual-energy X-ray absorptiometry before and after the intervention. RESULTS: Both groups showed significant ( p < 0.001) improvements in ULLST, LLLST, TLST, and the Cr group achieved greater ( p < 0.001) increases in these outcomes compared with PLA. For the Cr group, improvements in ULLST (7.1 ± 2.9%) were higher than those observed in LLLST (3.2 ± 2.1%) and TLST (2.1 ± 2.2%). Otherwise, for PLA group there was no significant difference in the magnitude of segmental muscle hypertrophy (ULLST = 1.6 ± 3.0%; LLLST = 0.7 ± 2.8%; TLST = 0.7 ± 2.8%). CONCLUSION: Our results suggest that Cr supplementation can positively augment muscle hypertrophy in resistance-trained young adult men, particularly in the upper limbs.