Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults.

We performed a systematic review, meta-analysis, and meta-regression to determine if increasing daily protein ingestion contributes to gaining lean body mass (LBM), muscle strength, and physical/functional test performance in healthy subjects. A protocol for the present study was registered (PROSPERO, CRD42020159001), and a systematic search of Medline, Embase, CINAHL, and Web of Sciences databases was undertaken. Only randomized controlled trials (RCT) where participants increased their daily protein intake and were healthy and non-obese adults were included. Research questions focused on the main effects on the outcomes of interest and subgroup analysis, splitting the studies by participation in a resistance exercise (RE), age (<65 or ≥65 years old), and levels of daily protein ingestion. Three-level random-effects meta-analyses and meta-regressions were conducted on data from 74 RCT. Most of the selected studies tested the effects of additional protein ingestion during RE training. The evidence suggests that increasing daily protein ingestion may enhance gains in LBM in studies enrolling subjects in RE (SMD [standardized mean difference] = 0.22, 95% CI [95% confidence interval] 0.14:0.30, P < 0.01, 62 studies, moderate level of evidence). The effect on LBM was significant in subjects ≥65 years old ingesting 1.2-1.59 g of protein/kg/day and for younger subjects (<65 years old) ingesting ≥1.6 g of protein/kg/day submitted to RE. Lower-body strength gain was slightly higher by additional protein ingestion at ≥1.6 g of protein/kg/day during RE training (SMD = 0.40, 95% CI 0.09:0.35, P < 0.01, 19 studies, low level of evidence). Bench press strength is slightly increased by ingesting more protein in <65 years old subjects during RE training (SMD = 0.18, 95% CI 0.03:0.33, P = 0.01, 32 studies, low level of evidence). The effects of ingesting more protein are unclear when assessing handgrip strength and only marginal for performance in physical function tests. In conclusion, increasing daily protein ingestion results in small additional gains in LBM and lower body muscle strength gains in healthy adults enrolled in resistance exercise training. There is a slight effect on bench press strength and minimal effect performance in physical function tests. The effect on handgrip strength is unclear.

Surgical Soft Tissue Management for Glenohumeral Deformity and Contractures in Brachial Plexus Birth Injury : A Systematic Review and Meta-analysis.

PURPOSE OF THE REVIEW: Consensus on the effects of soft tissue surgical intervention in the management of brachial plexus birth injury (BPBI) sequalae is lacking. The purpose of this review is to examine the available literature on the functional and structural outcomes following soft tissue surgical management of BPBI sequalae. RECENT FINDINGS: EMBASE, PubMed, and MEDLINE were searched for related literature from the point of database inception until April 2021. Relevant papers were screened by two reviewers independently and in duplicate. A meta-analysis was performed using a random effects model. A total of 25 studies (852 patients) were included in the review, with the number included in each meta-analysis varying based on outcome of interest. There were significant improvements from pre- to post-operative time points for the following measures: Mallet aggregate scores (5.0 points, p<0.0001), active external rotation in adduction (48.9°, p=0.003), passive external rotation in adduction (64.6°, p< 0.00001), active abduction (46.2°, p<0.00001), glenoid version (14.4°, p< 0.00001), and percentage of the humeral head anterior to the scapular line (17.53°, p< 0.00001). Furthermore, data revealed an overall complication rate of 9.3% (79/852 patients) and a major complication rate of 0.47% (4/852 patients). Patients with BPBI sequela experience statistically significant improvements in functional, structural, and range of motion outcomes of the GH joint following soft tissue surgical management. Understanding the ideal indications for each procedure and age of surgical management with future prospective studies will help to optimize surgical management of these patients.

A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults.

OBJECTIVE: We performed a systematic review, meta-analysis and meta-regression to determine if dietary protein supplementation augments resistance exercise training (RET)-induced gains in muscle mass and strength. DATA SOURCES: A systematic search of Medline, Embase, CINAHL and SportDiscus. ELIGIBILITY CRITERIA: Only randomised controlled trials with RET ≥6 weeks in duration and dietary protein supplementation. DESIGN: Random-effects meta-analyses and meta-regressions with four a priori determined covariates. Two-phase break point analysis was used to determine the relationship between total protein intake and changes in fat-free mass (FFM). RESULTS: Data from 49 studies with 1863 participants showed that dietary protein supplementation significantly (all p<0.05) increased changes (means (95% CI)) in: strength-one-repetition-maximum (2.49 kg (0.64, 4.33)), FFM (0.30 kg (0.09, 0.52)) and muscle size-muscle fibre cross-sectional area (CSA; 310 µm2 (51, 570)) and mid-femur CSA (7.2 mm2 (0.20, 14.30)) during periods of prolonged RET. The impact of protein supplementation on gains in FFM was reduced with increasing age (-0.01 kg (-0.02,-0.00), p=0.002) and was more effective in resistance-trained individuals (0.75 kg (0.09, 1.40), p=0.03). Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM. SUMMARY/CONCLUSION: Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults. Increasing age reduces and training experience increases the efficacy of protein supplementation during RET. With protein supplementation, protein intakes at amounts greater than ~1.6 g/kg/day do not further contribute RET-induced gains in FFM.