Analysis of the Additive Effects of Nutritional Strategies in Strength Training Interventions on Body Composition, Muscle Strength and Bone Mineral Density in Postmenopausal Women: A Systematic Review

During menopause, women experience a range of physiological changes, including reduction in skeletal muscle mass, bone mineral density, and an increase in fat mass. Although strength training and dietary strategies have individually been shown to counteract these changes, evidence for their combined effects is currently lacking. This review aims to investigate the combinatory effects on body composition, muscle strength, and bone mineral density. Three databases (PUBMED, Web of Science, and SPORTDiscus) were screened following the PRISMA guidelines. The PEDro scale was utilized to evaluate methodological quality and potential bias risk. The analyzed outcome parameters were body composition, muscle strength, and bone mineral density. A total of 34 studies including postmenopausal women (N = 1,541) were identified; 31 of these had a PEDro score of 6 or higher. In general, body composition, muscle strength, and bone mineral density have been significantly altered through systematic strength training. Eleven studies focused on an additional calorie deficit (250-750 kcal/day) which enhanced the reduction of fat mass. Protein intake was examined in nine studies and has no significant additional effect on muscle strength and lean body mass with a minimal intake of 0.8 g/kg bodyweight. Only a few studies could be identified on other nutritional and supplementation strategies. A total of three studies were identified investigating strength training in conjunction with amino acid supplementation, four studies examining calcium and vitamin D, four studies on creatine, one study on zataria multiflora, one study on omega-3 supplementation and one study on shatavari. Systematic strength training has been consistently demonstrated to improve body composition, strength capacity, and bone mineral density. However, the evidence supporting the effectiveness of additional nutritional and supplementation strategies remains inconclusive. While a calorie-restricted diet and adequate protein intake appear to promote favourable changes in body composition, the available data is still insufficient to derive specific and evidence-based recommendations regarding supplementation in conjunction with strength training. Moreover, research on additional nutritional and supplementation strategies remains inconsistent or scarce, underscoring the need for further studies to allow for more precise recommendations. PROSPERO Registration Number CRD42023412915 (12th April 2023).