BackgroundIt is important to include large sample sizes and different factors that influence the six-minute walking distance (6MWD) in order to propose reference equations for the six-minute walking test (6MWT). ObjectiveTo evaluate the influence of anthropometric, demographic, and physiologic variables on the 6MWD of healthy subjects from different regions of Brazil to establish a reference equation for the Brazilian population. MethodIn a multicenter study, 617 healthy subjects performed two 6MWTs and had their weight, height, and body mass index (BMI) measured, as well as their physiologic responses to the test. Delta heart rate (∆HR), perceived effort, and peripheral oxygen saturation were calculated by the difference between the respective values at the end of the test minus the baseline value. ResultsWalking distance averaged 586±106m, 54m greater in male compared to female subjects (p<0.001). No differences were observed among the 6MWD from different regions. The quadratic regression analysis considering only anthropometric and demographic data explained 46% of the variability in the 6MWT (p<0.001) and derived the equation: 6MWDpred=890.46-(6.11×age)+(0.0345×age2)+(48.87×gender)-(4.87×BMI). A second model of stepwise multiple regression including ∆HR explained 62% of the variability (p<0.0001) and derived the equation: 6MWDpred=356.658-(2.303×age)+(36.648×gender)+(1.704×height)+(1.365×∆HR). ConclusionThe equations proposed in this study, especially the second one, seem adequate to accurately predict the 6MWD for Brazilians.

Background Aortic stenosis is a valvular heart disease characterised by fixed obstruction of the left ventricular outflow. It can be managed by surgical aortic valve replacement (sAVR) or transcatheter aortic valve implantation (TAVI). This review aimed to describe the evidence supporting a cardiac rehabilitation programme on functional capacity and quality of life in aortic stenosis patients after sAVR or TAVI. Methods The search was conducted on multiple databases from January to March 2016. All studies were eligible that evaluated the effects of a post-interventional cardiac rehabilitation programme in aortic stenosis patients. The methodological quality was assessed using the PEDro scale. Meta-analysis was performed separately by procedure and between procedures. The walked distance during the six-minute walk test (6MWD) and Barthel index were evaluated. The analysis was conducted in Review Manager. Results Five studies were included (292 TAVI and 570 sAVR patients). The meta-analysis showed that a cardiac rehabilitation programme was associated with a significant improvement in 6MWD (0.69 (0.47, 0.91); P < 0.001) and Barthel index (0.80 (0.29, 1.30); P = 0.002) after TAVI and 6MWD (0.79 (0.43, 1.15); P < 0.001) and Barthel index (0.93 (0.67, 1.18); P < 0.001) after sAVR. In addition, the meta-analysis showed that the cardiac rehabilitation programme promoted a similar gain in 6MWD (4.28% (-12.73, 21.29); P = 0.62) and Barthel index (-1.52 points (-4.81, 1.76); P = 0.36) after sAVR or TAVI. Conclusions The cardiac rehabilitation programme improved the functional capacity and quality of life in aortic stenosis patients. Patients who underwent TAVI benefitted with a cardiac rehabilitation programme similar to sAVR patients.

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Recently, low-level laser (light) therapy (LLLT) has been used to improve muscle performance. This study aimed to evaluate the effectiveness of near-infrared light-emitting diode therapy (LEDT) and its mechanisms of action to improve muscle performance in an elite athlete. The kinetics of oxygen uptake (VO2), blood and urine markers of muscle damage (creatine kinase – CK and alanine) and fatigue (lactate) were analyzed. Additionally, some metabolic parameters were assessed in urine using proton nuclear magnetic resonance spectroscopy (1H NMR). A LED cluster with 50 LEDs (λ = 850 nm; 50mW 15 s; 37.5 J) was applied on legs, arms and trunk muscles of a single runner athlete 5 min before a high-intense constant workload running exercise on treadmill. The athlete received either Placebo-1-LEDT; Placebo-2-LEDT; or Effective-LEDT in a randomized double-blind placebo-controlled trial with washout period of 7 d between each test. LEDT improved the speed of the muscular VO2 adaptation (~−9 s), decreased O2 deficit (~−10 L), increased the VO2 from the slow component phase (~+348 ml min−1) and increased the time limit of exercise (~+589 s). LEDT decreased blood and urine markers of muscle damage and fatigue (CK, alanine and lactate levels). The results suggest that a muscular pre-conditioning regimen using LEDT before intense exercises could modulate metabolic and renal function to achieve better performance.

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