High-intensity exercise induces the accumulation of hydrogen ions, resulting in a decrease in plasma and muscle pH (i.e., metabolic acidosis), a key mechanism contributing to fatigue. Alleviating metabolic acidosis is crucial for improving high-intensity exercise performance. Voluntary hyperventilation increases carbon dioxide (CO₂) elimination, reduces arterial CO₂ partial pressure (hypocapnia), and an increase in plasma pH (i.e., respiratory alkalosis). Pre-exercise voluntary hypocapnic hyperventilation is a potentially effective intervention for alleviating metabolic acidosis and has been proposed to enhance exercise performance during cycling and resistance exercise. Furthermore, this technique may reduce aerobic metabolism while increasing anaerobic metabolism by decreasing active skeletal muscle blood flow and inhibiting oxidative phosphorylation during subsequent exercise. According to the overload principle, stimulating the anaerobic energy system during each high-intensity training session can improve its capacity, ultimately enhancing high-intensity exercise performance. High-intensity exercise performed under hypoxic conditions such as using hypoxic chambers or hypoxic gas inhalation, has traditionally been employed to stimulate anaerobic metabolism more effectively than normoxic environments. However, such hypoxic interventions are often inaccessible to many athletes due to logistical constraints. This short review highlights recent findings on the acute effects of pre-exercise voluntary hypocapnic hyperventilation on exercise performance and metabolic responses during high-intensity exercise.

Lactate administration has been suggested to affect energy metabolism by acting as an energy fuel and/or exhibiting various physiological responses. Although some previous studies have found that the intravenous infusion of lactate might increase energy expenditure, the effect of oral supplementation is unknown. In this study, we investigated the effects of acute oral lactate supplementation on energy metabolism during rest and exercise. Twelve healthy subjects (ten men and two women, average age 21.2 ± 0.8 years) participated in this single-blind, placebo-controlled, randomized crossover study. All subjects received two different supplements: supplements containing 1115 mg of lactate (LAC) and placebo supplements consisting of the same mass of glucose as the supplements in LAC (PLA). 1 hour after ingesting the supplements, they performed cycling exercise (unloaded, 70 rpm, 30 min). Measurements taken included oxygen consumption, blood lactate and glucose concentrations, heart rate, rating of perceived exertion, and gastric discomfort level. The results showed that the area under the curve for oxygen consumption during rest was significantly higher with LAC than with PLA treatment (LAC: 41.3 ± 3.7 ml/kg vs. PLA: 37.2 ± 5.5 ml/kg, p < 0.01). By contrast, no significant differences were observed between LAC and PLA treatments in any of the measurements during exercise. In conclusion, acute oral lactate supplementation increased oxygen consumption during rest.

This study sought to determine the concurrent validity and reliability of 6-s peak power test (6PT) on an air and magnetically braked cycle ergometer (Wattbike). Firstly, 17 physically active male and female adults performed 6PT and force-velocity test (FVT), consisting of 3 short all-out cycle sprints against 3 different loads on an electromagnetically braked cycle ergometer (Power Max), on the same day in part 1 of the study (i.e., concurrent validity). Subsequently, 11 out of those participants performed the respective tests on three different days (a total of 6 measurements for each participant) in part 2 of the study (i.e., inter-day reliability). The order of the tests was counterbalanced in both parts of the study, and maximal power output (MPO) and peak power output (6PP) derived from FVT and 6PT, respectively, were retained for the subsequent analyses. A high correlation between MPO and 6PP (r = 0.97, [95% CI: 0.90-0.99], p < 0.01) was observed with the standard error of the estimate of 59.7 W in part 1 of the study. Moreover, excellent inter-day reliability was confirmed for both tests in part 2 of the study (coefficient of variation: MPO = 2.08 [95% CI: 1.56-3.28%], 6PP = 2.81 [95% CI: 2.11-4.43%]; intraclass correlation coefficient: MPO = 0.987 [95%CI: 0.959-0.996], 6PP = 0.965 [95%CI: 0.899-0.990]). This study showed that a valid and reliable value is obtained from a single short all-out cycle test (i.e., 6PT), which would enable a frequent follow-up of power production capacity of individuals.

Strengthening of the hip external rotator muscles may improve pelvic floor muscle function. In this study, we examined the relationship between hip external rotator strength and pelvic floor muscle function in nulliparous women. This cross-sectional study included 59 women aged ≥18 years who had never given birth. Pelvic floor muscle function was measured using transabdominal ultrasound. Muscle strength during hip flexion, abduction, and external rotation, and handgrip strength were also measured. Multiple regression analysis was performed to examine the association between pelvic floor muscle function and hip external rotator strength. Fifty-five participants (average age: 20.3 years) were included in the final analysis. A single correlation was observed between pelvic floor muscle and hip flexor strength (r = 0.334, p = 0.013), hip abductors (r = 0.203, p = 0.038), and hip external rotators (r = 0.413, p < 0.001). Conversely, no relationship was observed between pelvic floor muscle function and handgrip strength (r = −0.124, p = 0.369). Multiple regression analysis revealed an independent association between pelvic floor muscle and hip external rotator muscle strength (β = 0.605, p = 0.032). However, no association was observed between pelvic floor muscle function and hip flexor (β = 0.086, p = 0.545), abductor (β = −0.052, p = 0.902), and handgrip strength (β = −0.012, p = 0.101). Hip external rotator muscle strength was associated with pelvic floor muscle function independently of hip flexor and abductor, and handgrip strength in nulliparous women. The findings suggest that hip external rotator strength may be related to pelvic floor muscle function in nulliparous women.