3.4.3. Muscle Recovery Adaptations

Perceived muscle soreness after a six-mile hike was reduced by 7% with post-exercise protein supplementation compared to increases of 10% and 16% in the placebo and control conditions, respectively (*p* < 0.05) [61]. The remaining studies found no significant difference between protein and placebo conditions for the recovery of muscle function [60], muscle damage [59] or both [52]. Blacker et al. [60] reported no effect of protein compared to CHO on muscle function recovery. At 48 hours post-exercise, knee extensor isometric force was reduced by 10 ± 10% for the low caloric placebo condition (*p* = 0.008) but had returned to baseline in the CHO (*p* = 0.199) and protein condition (*p* = 0.099). At 72 h post-exercise, participants in the placebo condition returned to baseline (*p* = 0.145), whereas both the CHO (*p* = 0.457) and protein conditions (*p* = 0.731) remained at baseline at 48 h post-exercise. Only one study assessed the impact of protein supplementation on markers of exercise induced muscle damage and inflammation [59]. It was found that there were no differences between protein and isocaloric placebo conditions for changes in blood concentrations of cortisol (placebo: −0.79 ± 0.89; protein: 1.39 ± 1.08 <sup>μ</sup>g·dL−1, *p* = 0.160), C-reactive protein (placebo: 0.13 ± 0.77; protein: 0.99 ± 0.16 mg·L−1, *p* = 0.305), creatine kinase (placebo: 278.65 ± 50.23; protein: 422.18 ± 149.87 <sup>U</sup>·L−1, *p* = 0.722) or aldolase (placebo: 2.06 ± 0.46; protein: 1.98 ± 0.91 <sup>U</sup>·L−1, *p* = 0.704). Based on the limited number of studies and available data, it was not possible to complete a meta-analysis of studies assessing the effect of protein supplementation on muscle recovery adaptations. These

limitations include the SD not being reported [61] and different outcome measures, such as muscle damage [59], muscle function [52,60] and muscle soreness [61].
