1.
Individual Participant Data Meta-Analysis Provides No Evidence of Intervention Response Variation in Individuals Supplementing With Beta-Alanine.
Esteves, GP, Swinton, P, Sale, C, James, RM, Artioli, GG, Roschel, H, Gualano, B, Saunders, B, Dolan, E
International journal of sport nutrition and exercise metabolism. 2021;(4):305-313
Abstract
Currently, little is known about the extent of interindividual variability in response to beta-alanine (BA) supplementation, nor what proportion of said variability can be attributed to external factors or to the intervention itself (intervention response). To investigate this, individual participant data on the effect of BA supplementation on a high-intensity cycling capacity test (CCT110%) were meta-analyzed. Changes in time to exhaustion (TTE) and muscle carnosine were the primary and secondary outcomes. Multilevel distributional Bayesian models were used to estimate the mean and SD of BA and placebo group change scores. The relative sizes of group SDs were used to infer whether observed variation in change scores were due to intervention or non-intervention-related effects. Six eligible studies were identified, and individual data were obtained from four of these. Analyses showed a group effect of BA supplementation on TTE (7.7, 95% credible interval [CrI] [1.3, 14.3] s) and muscle carnosine (18.1, 95% CrI [14.5, 21.9] mmol/kg DM). A large intervention response variation was identified for muscle carnosine (σIR = 5.8, 95% CrI [4.2, 7.4] mmol/kg DM) while equivalent change score SDs were shown for TTE in both the placebo (16.1, 95% CrI [13.0, 21.3] s) and BA (15.9, 95% CrI [13.0, 20.0] s) conditions, with the probability that SD was greater in placebo being 0.64. In conclusion, the similarity in observed change score SDs between groups for TTE indicates the source of variation is common to both groups, and therefore unrelated to the supplement itself, likely originating instead from external factors such as nutritional intake, sleep patterns, or training status.
2.
Efficacy and Safety of Inorganic Nitrate Versus Placebo Treatment in Heart Failure with Preserved Ejection Fraction.
Gui, Y, Chen, J, Hu, J, Ouyang, M, Deng, L, Liu, L, Sun, K, Tang, Y, Xiang, Q, Xu, J, et al
Cardiovascular drugs and therapy. 2020;(4):503-513
Abstract
BACKGROUND Heart failure with preserved ejection fraction (HFpEF) is common, yet there is a lack of effective treatments. In this meta-analysis, we assessed the efficacy and safety of inorganic nitrate in patients with HFpEF. METHODS AND RESULTS We systematically searched PubMed, Embase, and the Cochrane Library from the inception of the database through March 2020. We included randomized controlled trials that compared the efficacy and safety of inorganic nitrate with a placebo in the treatment of patients with HFpEF. The primary outcome of the meta-analysis was exercise capacity (measured as a change in peak oxygen uptake). We also assessed the effect of inorganic nitrate on diastolic function (measured as changes in E/A and E/e', assessed by echocardiography), quality of life (estimated using the Kansas City Cardiomyopathy Questionnaire), and rest and exercise hemodynamics (measured by invasive cardiac catheterization). In the pooled data analysis, there were no significant differences in peak oxygen uptake (mL/kg/min) [mean difference (MD), 0.25; 95% CI, - 0.07 to 0.57], diastolic function [E/A-standardized mean difference (SMD), 0.51; 95% CI, - 0.17 to 1.20; or E/e'-SMD, 0.02; 95% CI, - 0.23 to 0.27], or quality of life. However, a significant change was observed in the rest and exercise hemodynamics between the inorganic nitrate and placebo treatment in HFpEF patients. No study has reported the effect of inorganic nitrate on hospitalization and mortality of patients with HFpEF. CONCLUSIONS In patients with HFpEF, the use of inorganic nitrate is not associated with improvements in exercise capacity, diastolic function, and quality of life but is associated with significant changes in rest and exercise hemodynamics.
3.
Effects of Intermittent Fasting on Specific Exercise Performance Outcomes: A Systematic Review Including Meta-Analysis.
Correia, JM, Santos, I, Pezarat-Correia, P, Minderico, C, Mendonca, GV
Nutrients. 2020;(5)
Abstract
Intermittent fasting (IF) has been studied in athletes during Ramadan and in those willing to decrease adiposity while maintaining or increasing lean body mass. The purpose of this systematic review was to summarize the effects of IF on performance outcomes. We searched peer-reviewed articles in the following databases: PubMed, Web of Science and Sport Discus (up to December 2019). Studies were selected if they included samples of adults (≥18 years), had an experimental or observational design, investigated IF (Ramadan and time-restricted feeding (TRF)), and included performance outcomes. Meta-analytical procedures were conducted when feasible. Twenty-eight articles met the eligibility criteria. Findings indicated that maximum oxygen uptake is significantly enhanced with TRF protocols (SMD = 1.32, p = 0.001), but reduced with Ramadan intermittent fasting (Ramadan IF; SMD = -2.20, p < 0.001). Additional effects of IF may be observed in body composition (body mass and fat mass). Non-significant effects were observed for muscle strength and anaerobic capacity. While Ramadan IF may lead to impairments in aerobic capacity, TRF may be effective for improving it. As there are few studies per performance outcome, more research is needed to move the field forward.
4.
The Effect of Nitrate Supplementation on Exercise Tolerance and Performance: A Systematic Review and Meta-Analysis.
Van De Walle, GP, Vukovich, MD
Journal of strength and conditioning research. 2018;(6):1796-1808
Abstract
Van De Walle, GP and Vukovich, MD. The effect of nitrate supplementation on exercise tolerance and performance: a systematic review and meta-analysis. J Strength Cond Res 32(6): 1796-1808, 2018-The purpose of this article was to systematically review the current literature and evaluate the overall efficacy of nitrate supplementation on exercise tolerance and performance by meta-analysis. Studies were eligible for inclusion if they met the following criteria: (a) were an experimental trial published in an English peer-reviewed journal; (b) compared the effects of inorganic nitrate consumption with a non-bioactive supplement control or placebo; (c) used a quantifiable measure of exercise performance; and (d) was carried out in apparently healthy participants without disease. A total of 29 studies were identified that investigated the effects of nitrate supplementation on exercise tolerance or performance in accordance with the criteria outlined. Analysis using time to exhaustion as the outcome variable revealed a significant effect of nitrate supplementation on exercise tolerance (ES = 0.28; 95% confidence interval [CI]: 0.08-0.47; p = 0.006) compared with placebo. Analysis using time to complete a specific distance as the outcome variable revealed no significant effect of nitrate supplementation on exercise performance (ES = -0.05; 95% CI: -0.28 to 0.17; p = 0.64) compared with placebo. Nitrate supplementation is likely to improve exercise tolerance and capacity that may improve exercise performance. More research is required to determine the optimal dose and duration of nitrate supplementation. It would also be important to consider the type of athlete performing the exercise and the duration, intensity, and mode of the exercise performed because these factors are likely to influence the efficacy of nitrate supplementation.