RESUMO
The purpose of this review was to critically appraise articles that have investigated the association between lower-body strength and power during load carriage in tactical personnel. Literature databases were searched with specific search terms, yielding 921 articles. Additional studies found from article reference lists were also assessed for eligibility. Out of these articles, 16 met the inclusion/exclusion criteria and were critically appraised. Articles were assessed by the Downs and Black evaluation tool with inter-rater agreement determined by Cohen's kappa and final results graded according to the Kennelly quality grading system. Of the 940 identified articles, 16 studies met the criteria for inclusion in this review. The average score of the eligible articles was 58%, considered to be of fair quality by the Kennelly grading system. The strength and volume of evidence reviewed suggests that: measures of lower-body strength and power can predict load carriage performance and appear to be important physical factors for load carriage ability, and that load carriage tasks negatively impact the performance of leg strength and power. Together these findings suggest that leg strength and power should be important considerations for tactical personnel training and assessment, as well as managing the impact of load carriage on tactical performance.
RESUMO
BACKGROUND & AIM: Calorie restriction (CR) reduces co-morbidities associated with obesity, but also reduces lean mass thereby predisposing people to weight regain. Since we demonstrated that glycine supplementation can reduce inflammation and muscle wasting, we hypothesized that glycine supplementation during CR would preserve muscle mass in mice. METHODS: High-fat fed male C57BL/6 mice underwent 20 days CR (40% reduced calories) supplemented with glycine (1 g/kg/day; n = 15, GLY) or l-alanine (n = 15, ALA). Body composition and glucose tolerance were assessed and hindlimb skeletal muscles and epididymal fat were collected. RESULTS: Eight weeks of a high-fat diet (HFD) induced obesity and glucose intolerance. CR caused rapid weight loss (ALA: 20%, GLY: 21%, P < 0.01), reduced whole-body fat mass (ALA: 41%, GLY: 49% P < 0.01), and restored glucose tolerance to control values in ALA and GLY groups. GLY treated mice lost more whole-body fat mass (14%, p < 0.05) and epididymal fat mass (26%, P < 0.05), less lean mass (27%, P < 0.05), and had better preserved quadriceps muscle mass (4%, P < 0.01) than ALA treated mice after 20 d CR. Compared to the HFD group, pro-inflammatory genes were lower (P < 0.05), metabolic genes higher (P < 0.05) and S6 protein phosphorylation lower after CR, but not different between ALA and GLY groups. There were significant correlations between %initial fat mass (pre CR) and the mRNA expression of genes involved in inflammation (r = 0.51 to 0.68, P < 0.05), protein breakdown (r = -0.66 to -0.37, P < 0.05) and metabolism (r = -0.59 to -0.47, P < 0.05) after CR. CONCLUSION: Taken together, these findings suggest that glycine supplementation during CR may be beneficial for preserving muscle mass and stimulating loss of adipose tissue.
