Effects of 16 weeks of two different high-protein diets with either resistance or concurrent training on body composition, muscular strength and performance, and markers of liver and kidney function in resistance-trained males

Abstract

Purpose It is unclear whether resistance (RT) and concurrent training (CT; resistance plus endurance training) combined with different protein intakes have differential effects on muscle hypertrophy, strength, and performance. Therefore, we compared the effects of two high-protein diets (1.6 or 3.2 g.kg −1. d −1 ) during 16 weeks of either CT or RT alone in resistance-trained males. Methods Forty-eight resistance-trained males (age: 26 ± 6 yr, body mass index: 25.6 ± 2.9 kg.m −2 ) performed 16 weeks (four sessions·w −1 ) of CT or RT with either 1.6 g.kg −1. d −1 protein (CT1; n = 12; RT1; n = 12) or 3.2 g.kg −1. d −1 protein (CT2; n = 12; RT2; n = 12). Training adaptations were assessed pre-, mid-, and post-intervention. Results All measures of performance (endurance, vertical jump, and pull-up), lean mass, muscle strength, and power significantly increased post-intervention in all groups, but peak power gains were greater in RT2 compared with RT1 and CT1 ( p < .05). VO 2max significantly increased in both CT groups ( p < .001). Select biochemical markers of kidney and liver function significantly increased within the RT2 and CT2 groups ( p < .05), however, no between-group differences were apparent ( p > .05). Conclusions With the exception of peak power, intake of 1.6 g.kg −1. d −1 of protein appears sufficient to maximize gains in lean mass, muscle strength, performance, and aerobic capacity during both RT and CT without influencing markers of kidney and liver function, indicating this daily protein amount is effective and safely tolerated in young, healthy adults.

High-Protein Diets during either Resistance or Concurrent Training Have No Detrimental Effect on Bone Parameters in Resistance-Trained Males

“…The current investigation enlisted a sample of 48 male participants who were young, healthy, and engaged in RT. The same participant cohort was used in a previous publication that investigated the effects of different high protein intakes on body composition, muscular strength and performance, and markers of liver and kidney [ 30 ]. These individuals were between the ages of 18 and 36 and were recruited via the use of advertising on various social media platforms.…”

“…As previously published [30], following the collection of baseline measures, participants underwent a familiarization process with this research tests and procedures. Subsequently, they were randomized to one of four groups using the use of an online resource, namely www.randomizer.org (accessed on 30 January 2022): CT + 1.6 g kg −1 d −1 of protein (CT1; n = 12), CT + 3.2 g kg −1 d −1 of protein (CT2; n = 12), RT + 1.6 g kg −1 d −1 of protein (RT1; n = 12), or RT + 3.2 g kg −1 d −1 of protein (RT2; n = 12).…”

Timing matters? The effects of two different timing of high protein diets on body composition, muscular performance, and biochemical markers in resistance-trained males

“…Relative to total daily protein intakes, higher protein intakes are superior to lower protein intakes (1,(6)(7)(8). A threshold for total daily protein intake has been reported to be approximately 1.6 g kg −1 d −1 for individuals looking to improve hypertrophy outcomes (1,6,9).…”

“…Relative to total daily protein intakes, higher protein intakes are superior to lower protein intakes (1,(6)(7)(8). A threshold for total daily protein intake has been reported to be approximately 1.6 g kg −1 d −1 for individuals looking to improve hypertrophy outcomes (1,6,9). Protein intakes surpassing this threshold are not likely to provide further benefit relative to gains in skeletal muscle mass (SMM) or strength (10,11).…”

“…For individuals looking to optimize improvements in muscle hypertrophy and strength, participation in a resistance training program in conjunction with adequate dietary protein intake is necessary ( 1 , 2 ). Key variables in resistance training that are often manipulated to maximize muscle hypertrophy include training volume, intensity, and frequency ( 3 ).…”