Changes in athlete training patterns due to COVID-19 pandemic among Brazilian athletes.

In sports, training needs to be done according to various training patterns to optimize performance. However, this has been a major challenge to athletes due to the COVID-19 pandemic, therefore describing the impacts of lockdown caused by the COVID-19 pandemic on the athlete's training routine is necessary. 52 Brazilian athletes (Age: 31.5±10.3 years; Body Mass Index: 23.9±3.5 kg/m²), Olympic and Paralympic sports practitioners (professional and recreational) answered an online questionnaire [frequency, duration and intensity (subjective perception of effort) of training sessions], before and during lockdown (July to November/2020). The weekly training frequency (sessions/week) reduced by 48.1% (n=25) and was significantly higher among those who performed more than eight sessions before the pandemic (75% of them, p<0.000). The duration of the sessions (hours/day) decreased by 55.8% (n=29) and was significantly higher in athletes who performed training lasting more than one hour/day [75.9% of them (n=22)] and 24.1% (n= 7) performed training for more than two hours/day (p=0.132). The subjective perception of effort significantly decreased by 56%, from 8.4±1.2 to 5.5±1.7 (p=0.001). Because of the lockdown, athletes have suffered a reduction in the frequency, volume and intensity of their training sessions, but only in those with higher pre-pandemic training loads.

Validity of a Smartphone Application and Chest Strap for Recording RR Intervals at Rest in Athletes.

OBJECTIVE: To evaluate the accuracy of the smartphone application (app) HRV Expert (CardioMood) and a chest strap (H10 Polar) for recording R-R intervals compared with electrocardiogram (ECG). METHODS: A total of 31 male recreational runners (age 36.1 [6.3] y) volunteered for this study. R-R intervals were recorded simultaneously by the smartphone app and ECG for 5 minutes to analyze heart-rate variability in both the supine and sitting positions. Time-domain indexes (heart rate, mean R-R, SD of RR intervals, count of successive normal R-R intervals differing by more than 50 ms, percentage of successive normal R-R intervals differing by more than 50 ms, and root mean square of successive differences between normal R-R intervals), frequency-domain indexes (low frequency, normalized low frequency, high frequency, normalized high frequency, low-frequency to high-frequency ratio, and very low frequency), and nonlinear indexes (SD of instantaneous beat-to-beat variability and long-term SD of continuous R-R intervals) were compared by unpaired t test, Pearson correlation, simple linear regression, and Bland-Altman plot to evaluate the agreement between the devices. RESULTS: High similarity with P value varying between .97 and 1.0 in both positions was found. The correlation coefficient of the heart-rate-variability indexes was perfect (r = 1.0; P = .00) for all variables. The constant error, standard error of estimation, and limits of agreement between ECG and the smartphone app were considered small. CONCLUSION: The smartphone app and chest strap provide excellent ECG compliance for all variables in the time domain, frequency domain, and nonlinear indexes, regardless of the assessed position. Therefore, the smartphone app replaces ECG for any heart-rate-variability analysis in runners.

Oxidative stress does not influence weight loss induced by aerobic training in adults: randomized clinical trials.

BACKGROUND: High levels of oxidative stress promote degradation of the cell membrane impairing cellular function in fat oxidation. However, the influence of oxidative stress on exercise-induced weight-loss has not yet been investigated. Therefore, the aim of this study was to verify the influence of a lipidic peroxidation marker (malondialdehyde, MDA) and antioxidant status (total antioxidant capacity marker, TAC) on the magnitude of weight-loss by aerobic-induced exercise in previously sedentary overweight or obese individuals. METHODS: Seventy-five physically inactive adults were randomized into experimental (N.=58) and control (N.=17) groups, who engaged in a 12-week program of aerobic training walking and/or running (3 to 5 days/week) or stretching (1 day/week), respectively. Body composition (DXA), aerobic capacity (ergospirometric) and blood collections for oxidative stress analysis (MDA and TAC) were determined before and after the experimental protocol. Two-way ANOVA for repeated measures or Friedman's test were used to evaluate differences in time/group interaction. Pearson correlation was used to verify the relationship between the variables of oxidative stress and of body composition. RESULTS: Significant reduction was found in fat body mass of experimental when compared to control group (-1.3±1.9 kg versus -0.3±1.3, P=0.04). Experimental group also altered significantly the total body mass (-1.2±4.7 kg; effect size 0.44), body mass index - BMI (-0.3±1.1 effect size 0.37), fat percentage (1.3±1.6%; effect size 0.50) and lean body mass (0.6±1.5 kg; effect size 0.32).There was increase in MDA of 2.3 µmol/L to 2.7 µmol/L (P=0.00), without changes to TAC (25.6±13.9% to 28.0±10.4%). No correlation was found between these variations in body composition with either the initial values of MDA and TAC or delta variation of these indicators of oxidative stress in response to the training program. CONCLUSIONS: Indicators of oxidative stress (MDA and TAC) does not influence the magnitude of weight-loss induced by aerobic training.