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The aim of this study is to develop equations for aerobic exercise prescription for the intensities of 50, 60, 70 and 80% in healthy subjects of both sexes. Method. This is a cross-sectional study with convenience sampling drawn from a database of 228 healthy subjects who were randomized into the regression group (GR: 197 subjects (male = 143 and female = 54)) and cross-validation group (CVG: 31 individuals [men = 20 and women = 11]). Kohavi’s assumptions were followed in relation to cross-validation and bootstrap for precision estimation and model selection. The GR was used to build the estimation equations from the multiple linear regression. The CVG was determined to analyze the validity in the estimation equations. The equations to determine the intensities were constructed by means of multiple regression, the independent variables were determined by the stepwise method, observing the significance level of p < 0.05. Results. The reliability level of Cronbach’s alpha of the multiple linear regression equations was moderate for the intensity of 50% (0.51); for the intensities of 60, 70 and 80%, it corresponded to 0.50, 0.53 and 0.57, respectively. Conclusion. The results show that it is possible to apply the equations in the determination of aerobic exercise intensities for healthy individuals. However, the need for further studies in other populations to prove the reliability of the proposed equations is evident.

The objective was to analyze anthropometric and physical performance variables as a function of chronological age and biological maturity in young Chilean tennis players. The study was observational, cross-sectional, with descriptive and analytical characteristics. Eighty-seven tennis players were evaluated (58 men 15.1 ± 0.8 years and 29 women, 15.3 ± 0.8 years). The measured anthropometric variables were a sprint test of 20m, a modified agility test, a sit-and-reach test and shoulder flexibility, manual grip strength, horizontal jump in feet, a medicine ball throw, a countermovement vertical jump, an abalakov vertical jump and a 20-m shuttle-run test. The growth velocity acceleration peak (APHV), skeletal muscle mass and fat mass were calculated, R2 and standard error of estimate (SEE) were examined. The results show that chronological age explained the anthropometric variables between 1 and 23% in men and 1 and 29% in women, by biological age, variables were explained between 3 and 53% in men and 2 and 42% in women. Of the physical performance variables, chronological age described between 2 and 24% of them in men and 1 and 29% in women, the same were explained by biological age between 1 and 19% in men and 1 and 26% in women. We conclude that anthropometric variables showed a better relationship with biological age, except for volume of fat tissue, while physical performance variables showed low association with both biological and chronological age.

COVID-19 causes cardiovascular and lung problems that can be aggravated by confinement, but the practice of physical activity (PA) could lessen these effects. The objective of this study was to evaluate the association of maximum oxygen consumption (V˙O2max) with vaccination and PCR tests in apparently healthy Chilean adults. An observational and cross-sectional study was performed, in which 557 people from south-central Chile participated, who answered an online questionnaire on the control of COVID-19, demographic data, lifestyles, and diagnosis of non-communicable diseases. V˙O2max was estimated with an abbreviated method. With respect to the unvaccinated, those who received the first (OR:0.52 [CI:0.29;0.95], p = 0.019) and second vaccine (OR:0.33 [CI:0.18;0.59], p = 0.0001) were less likely to have an increased V˙O2max. The first vaccine was inversely associated with V˙O2max (mL/kg/min) (β:−1.68 [CI:−3.06; −0.3], p = 0.017), adjusted for BMI (β:−1.37 [CI:−2.71; −0.03], p = 0.044) and by demographic variables (β:−1.82 [CI:−3.18; −0.46], p = 0.009); similarly occur for the second vaccine (β: between −2.54 and −3.44, p < 0.001) on models with and without adjustment. Having taken a PCR test was not significantly associated with V˙O2max (mL/kg/min). It is concluded that vaccination significantly decreased V˙O2max, although it did not indicate cause and effect. There is little evidence of this interaction, although the results suggest an association, since V˙ O2max could prevent and attenuate the contagion symptoms and effects.