Background: The aim of this study was to compare the number of repetitions to volitional failure, the blood lactate concentration, and the perceived exertion to resistance training with and without an airflow-restricting mask. Methods: Eight participants participated in a randomized, counterbalanced, crossover study. Participants were assigned to an airflow-restricting mask group (MASK) or a control group (CONT) and completed five sets of chest presses and parallel squats until failure at 75% one-repetition-maximum test (1RM) with 60 s of rest between sets. Ratings of perceived exertion (RPEs), blood lactate concentrations (Lac−), and total repetitions were taken after the training session. Results: MASK total repetitions were lower than those of the CONT, and (Lac−) and MASK RPEs were higher than those of the CONT in both exercises. Conclusions: We conclude that an airflow-restricting mask in combination with resistance training increase perceptions of exertion and decrease muscular performance and lactate concentrations when compared to resistance training without this accessory. This evidence shows that the airflow-restricting mask may change the central nervous system and stop the exercise beforehand to prevent some biological damage.

The aim of this study was to compare the velocities found in the protocols used to measure the indirect individual anaerobic threshold (IAT ind ), glucose threshold (GT) and critical velocity (CV) with the gold standard, the maximum lactate steady state (MLSS) protocol. Fourteen physically active young adults (23±3.1 years; 72±10.97 kg; 176±7 cm; 21±5.36% body fat) performed a 3000-m track running test to determine IAT ind using the prediction equation and an incremental test on a treadmill to determine GT. The CV was identified by linear regression of the distance-time relationship based on 3000-m and 500-m running performance. The MLSS was identified using two to five tests on different days to identify the intensity at which there was no increase in blood lactate concentration greater than 1 mmol/L between the 10 th and 30 th minute. A significant difference was observed between mean CV and MLSS (P≤0.05) and there was a high correlation between MLSS and IAT ind (R 2 =0.82; P≤0.01) and between MLSS and GT (R 2 =0.72; P≤0.01). The Bland-Altman method showed agreement between MLSS and IAT ind [mean difference -0.24 (confidence interval -1.72 to 1.24) km/h] and between MLSS and GT [0.21 (-1.26 to 1.29) km/h]. We conclude that the IAT ind and GT can predict MLSS velocity with good accuracy, thus making the identification of MLSS practical and efficient to prescribe adequate intensities of aerobic exercise.

This study aimed to verify whether different stage length affects the intensity of the Blood Glucose Threshold (BGT), and the agreement between evaluators for BGT determination. Methods: Fourteen subjects attended the laboratory during the first session to perform anthropometric measures and become familiar with procedures. In the following three sessions, subjects performed an incremental test on the ergometer bicycle and in each test a different protocol was performed in randomized order (1, 3-and 5-min stage) to identify BGT. Three different evaluators determined the BGT. Results: Our data show that the BGT is stage length-dependent (1, 3-and 5-min; P<0.0001). The intraclass correlation coefficient showed that there was a strong correlation among evaluators for all protocols (ICC = 0.8 to 1 min; ICC = 0.8 to 3 min; and ICC 0.9 to 5 min). However, one evaluator determined the BGT at a higher intensity than others. The peak load was lower at long stage length. Conclusion: We concluded that stage length influences the BGT intensity determination. The BGT presents a good agreement among evaluators. However, a minimum of two evaluators is needed for BGT determination. The peak load is affected by stage length.