Influence of the ACTN3 Genotype and the Exercise Intensity on the Respiratory Exchange Ratio and Excess Oxygen Consumption After Exercise.

ABSTRACT: de L. Corrêa, H, Ribeiro, HS, Maya, ÁTD, Neves, RP, de Moraes, MR, Lima, RM, Nóbrega, OT, and Ferreira, AP. Influence of the ACTN3 genotype and the exercise intensity on the respiratory exchange ratio and excess oxygen consumption after exercise. J Strength Cond Res 35(5): 1380-1388, 2021-This study aimed to assess the respiratory exchange ratio (RER) and excess postexercise oxygen consumption (EPOC) after high-intensity interval training and continuous moderate-intensity aerobic training in accordance with the ACTN3 genotype. A cross-sectional study with 30 physically active individuals who participated in 3 experimental sessions, as follows: a high-intensity interval aerobic exercise, for 3 minutes at 115% anaerobic threshold, with 90 seconds of passive recovery; a continuous moderate-intensity aerobic exercise at 85% anaerobic threshold; and a control session. Respiratory exchange ratio and V̇o2 were obtained through an indirect, calorimetry-based gas analysis method, using a breath-by-breath approach, assessed at baseline, during the trials, and at 1, 2, 3, and 4 hours after exercise. We found that lower postexercise RER values were observed only in subjects with the X allele, in both the high- and the moderate-intensity training protocols. Homozygous RR subjects showed no differences in postexercise RER compared with the scores at the control day. After both sessions of exercise, EPOC levels were higher compared with scores at the control day for 2 hours among X allele carriers, and only in the first hour among RR homozygous. Thus, the RER and EPOC presented different responses after moderate and intense exercise according to the ACTN3 genotype. Moreover, individuals with the X allele of the ACTN3 gene show a higher oxidation of fats in the postexercise period.

High Supervised Resistance Training in Elderly Women: The Role of Supervision Ratio.

The objective of this study was to compare the effects of very high supervision (VHS-RT) versus high supervision (HS-RT) ratio resistance training (RT) on irisin, brain-derived neurotrophic factor (BNDF), muscle strength, functional capacity, and body composition in elderly women. Participants performed daily undulating periodized RT over 16 weeks with two different supervision ratios: VHS-RT at 1:2 (supervisor/subject) or HS-RT at 1:5. Serum was used to analyze brain derived neurotropic factor (BDNF) and irisin by enzyme-linked immunosorbent assay (ELISA). Body composition was evaluated by dual-energy X-ray absorptiometry, while functional capacity was evaluated using the Six-minute walk test, and Timed Up and Go (TUG). One- repetition maximum (1RM) was determined for bench press and 45° leg press exercises. For both groups, no differences between baseline and post-training were identified for irisin and lean mass (p > 0.05). Both groups improved bench press 1-RM, 45° leg press 1-RM, and TUG (p < 0.05). The VHS-RT group displayed higher effect sizes for 1-RM tests. Moreover, only VHS-RT group reduced body fat and body fat percentage (p < 0.05). In contrast, the HS-RT increased BDNF (p < 0.01). In this sense, RT enhances muscle strength and functional capacity in elderly women independent of supervision ratio. A greater supervision ratio during RT may induce more improvements in muscle strength, and body composition than lower supervision ratio during RT.

Hydration Status After an Ironman Triathlon: A Meta-Analysis.

The Ironman is one of the most popular triathlon events in the world. Such a race involves a great number of tactical decisions for a healthy finish and best performance. Dehydration is widely postulated to decrease performance and is known as a cause of dropouts in Ironman. Despite the importance of hydration status after an Ironman triathlon, there is a clear lack of review and especially meta-analysis studies on this topic. Therefore, the objective was to systematically review the literature and carry out a meta-analysis investigating the hydration status after an Ironman triathlon. We conducted a systematic review of the literature up to June 2016 that included the following databases: PubMed, SCOPUS, Science Direct and Web of Science. From the initial 995 references, we included 6 studies in the qualitative analysis and in the meta-analysis. All trials had two measures of hydration status after a full Ironman race. Total body water, blood and urine osmolality, urine specific gravity and sodium plasma concentration were considered as hydration markers. Three investigators independently abstracted data on the study design, sample size, participants' and race characteristics, outcomes, and quantitative data for the meta-analysis. In the pooled analysis, it seems that the Ironman event led to a moderate state of dehydration in comparison to baseline values (SMD 0.494; 95% CI 0.220 to 0.767; p = 0.001). Some evidence of heterogeneity and consistency was also observed: Q = 19.6; I2 = 28.5%; τ2 = 2.39. The results suggest that after the race athletes seem to be hypo-hydrated in comparison to baseline values.