No abstract

The digit ratio (2D:4D) is said to be a potential marker of exposure to prenatal sex steroids. Some studies suggest that the 2D:4D is also linked with the testosterone response to challenging situations due to organizational effect of prenatal hormonal milieu on adult endocrine functioning. However, up to date, there were only four studies (conducted on small samples) that examined the 2D:4D and the testosterone response to a challenging situation (i.e. physical exertion or aggressive context). Here, we examined the relationship between the 2D:4D and the testosterone change under an acute exercise among 97 men. We found that the digit ratios (the right 2D:4D, the left 2D:4D, and the right minus left 2D:4D) were neither predictors of pre-exercise testosterone, nor the change in testosterone level after a cycling task. Our results add a contradictory to previous studies evidence in a discussion on the links of the 2D:4D and the testosterone change. More than 100 years ago, a difference in the length of the 2 nd , index finger (2D) and the 4 th , ring finger (4D) has been described 1. Further studies provided evidence that men and women vary when it comes to the magnitude of this difference 2. The ratio between the length of the 2 nd and the 4 th finger (2D:4D) has been reported to be smaller among men compared to women (men have longer the 4 th finger than the 2 nd finger) (but see also: 3,4). Since then, researchers have been interested in the origins and implications of the 2D:4D sexual dimorphism. Manning and colleagues 5 suggested that the difference between the 2D:4D among men and women develops during gestation under prenatal sex steroids control. The 2D:4D is said to be directly connected with the exposure to androgens in the uterus (with the lower digit ratios associated with the exposure to higher levels of testosterone, and higher digit ratios associated with the exposure to lower levels of testosterone). Hence, the 2D:4D is perceived as an index of prenatal testosterone level. However, correlational studies on the relationship between the 2D:4D and the prenatal testosterone level conducted on human fetuses brought conflicting results 6-11. Similar, mixed results have been found in experimental studies on animals 12,13 , thus, it is not surprising that such links are perceived as questionable and unclear 14-16. Even more speculative is that some researchers presume that the low 2D:4D may reflect higher adult testosterone 17-27. Interestingly, only a few studies reported a negative link between the 2D:4D and adult sex hormone levels 5,18-21,23 , whereas a meta-analysis conducted by Hönekopp et al. 28 and Zhang et al. 15 found no such association. Because there are many mixed findings on the mechanism of the observed differences in digit ratios 12-14,28 , and at the same time, there is a constantly growing body of literature showing positive associations between the 2D:4D and, for instance, psychological or physiological 29,30 characteristics, new hypotheses explaining the potential relationship between the...

Hebisz, R, Hebisz, P, Danek, N, Michalik, K, and Zatoń, M. Predicting changes in maximal oxygen uptake in response to polarized training (sprint interval training, high-intensity interval training, and endurance training) in mountain bike cyclists. J Strength Cond Res 36(6): 1726–1730, 2022—The aim of this study was to determine the predictors of change in maximal oxygen uptake (ΔV̇o2max) in response to a polarized training program. Twenty well-trained mountain bike cyclists completed an 8-week intervention of sprint interval training (SIT) (8–16 30-second maximal sprints), high-intensity interval training (4–6 bouts at 85–95% maximal aerobic power), and endurance training (2–3 hours cycling at 70–80% power at the ventilatory threshold). An incremental exercise test was performed to determine preintervention and postintervention maximal oxygen uptake (V̇o2max) and maximal pulmonary ventilation (VEmax) normalized to lean body mass (LBM). The frequency and time domain of heart rate variability (HRV) was also determined during recovery after moderate warm-up in the first and last SIT. Training status was quantified as the total distance cycled in the previous year. V̇o2max, VEmax, and the root mean square of the successive differences of normal-to-normal time interval between heartbeats (RMSSD), which is the time domain of HRV all increased significantly. Multiple significant correlations were observed between ΔV̇o2max and training status and baseline measures of VEmax·LBM−1, RMSSD, and V̇o2max·LBM−1 and a regression equation was developed (r = 0.87, r2 = 0.76; p = 0.0001). The change in V̇o2max in response to polarized training can be predicted with high accuracy based on several measurable variables.

Background: The aim of the study was to compare acute physiological, biochemical, and perceptual responses during sprint interval exercise (SIE) with breathing through a device increasing added respiratory dead space volume (ARDSV) and without the device. Methods: The study involved 11 healthy, physically active men (mean maximal oxygen uptake: 52.6 ± 8.2 mL∙kg1∙min−1). During four visits to a laboratory with a minimum interval of 72 h, they participated in (1) an incremental test on a cycle ergometer; (2) a familiarization session; (3) and (4) cross-over SIE sessions. SIE consisted of 6 × 10-s all-out bouts with 4-min active recovery. During one of the sessions the participants breathed through a 1200-mL ARDSv (SIEARDS). Results: The work performed was significantly higher by 4.4% during SIEARDS, with no differences in the fatigue index. The mean respiratory ventilation was significantly higher by 13.2%, and the mean oxygen uptake was higher by 31.3% during SIEARDS. Respiratory muscle strength did not change after the two SIE sessions. In SIEARDS, the mean pH turned out significantly lower (7.26 vs. 7.29), and the mean HCO3– concentration was higher by 7.6%. Average La− and rating of perceived exertion (RPE) did not differ between the sessions. Conclusions: Using ARDSV during SIE provokes respiratory acidosis, causes stronger acute physiological responses, and does not increase RPE.

Background: Knowledge of acute responses to different sprint interval exercise (SIE) helps to implement new training programs. The aim of this study was to compare the acute physiological, metabolic and perceptual responses to two different SIE cycling protocols with different recovery durations. Methods: Twelve healthy, active male participants took part in this study and completed four testing sessions in the laboratory separated by a minimum of 72h. Two SIE protocols were applied in randomized order: SIE6×10”/4’—six “all-out” repeated 10-s bouts, interspersed with 4-min recovery; and SIESERIES—two series of three “all-out” repeated 10-s bouts, separated by 30-s recovery and 18-min recovery between series. Protocols were matched for the total work time (1 min) and recovery (20 min). Results: In SIESERIES, peak oxygen uptake and peak heart rate were significantly higher (p < 0.05), without differences in peak blood lactate concentration and mean rating of perceived exertion compared to SIE6×10”/4’. There were no differences in peak power output, peak oxygen uptake and peak heart rate between both series in SIESERIES. Conclusions: Two series composed of three 10-s “all-out” bouts in SIESERIES protocol evoked higher cardiorespiratory responses, which can provide higher stimulus to improve aerobic fitness in regular training.

The avoidance of respiratory muscle fatigue and its repercussions may play an important role in swimmers’ health and physical performance. Thus, the aim of this study was to investigate whether a six-week moderate-intensity swimming intervention with added respiratory dead space (ARDS) resulted in any differences in respiratory muscle variables and pulmonary function in recreational swimmers. A sample of 22 individuals (recreational swimmers) were divided into an experimental (E) and a control (C) group, observed for maximal oxygen uptake (VO2max). The intervention involved 50 min of front crawl swimming performed at 60% VO2max twice weekly for six weeks. Added respiratory dead space was induced via tube breathing (1000 mL) in group E during each intervention session. Respiratory muscle strength variables and pulmonary and respiratory variables were measured before and after the intervention. The training did not increase the inspiratory or expiratory muscle strength or improve spirometric parameters in any group. Only in group E, maximal tidal volume increased by 6.3% (p = 0.01). The ARDS volume of 1000 mL with the diameter of 2.5 cm applied in moderate-intensity swimming training constituted too weak a stimulus to develop respiratory muscles and lung function measured in the spirometry test.

The aim of the study was to investigate the response of testosterone and cortisol to sprint interval exercises (SIEs) and to determine the role of dominance. The experiment was conducted in a group of 96 men, divided into endurance-training, strength-training, and non-training groups. Participants performed SIEs consisting of 5 × 10-s all-out bouts with a 50-s active recovery. Using the passive drool method, testosterone and cortisol concentrations were measured in saliva samples at rest at 10 min pre and 12 min post exercise. Participants’ heart rate (HR) was measured during the whole exercise. Dominance was assessed by the participants before the study; the rating of perceived exertion (RPE) was measured immediately after each bout. The study showed that those who trained in endurance and strength sports had significantly lower mean HRs after five acute 10-s interval bouts than those in the non-training group (p = 0.006 and p = 0.041, respectively). Dominance has an inverse relation to changes in HR; however, it has no relation to hormone response. No significant differences were observed in testosterone and cortisol changes in the endurance-training, strength-training, and non-training groups after SIE (p > 0.05), which may indicate that the exercise volume was too low.

Introduction. The aim of the study was to verify the influence of warm-up before a ramp incremental exercise test with linearly increasing loads on the maximal values of physiological variables which determine performance.Material and methods. Thirteen healthy and physically active male students (age = 23.3 ± 1.5 years, body height = 179.1 ± 8.6 cm and body mass = 79.5 ± 9.1 kg) completed a cross-over comparison of two incremental exercise test interventions – an incremental exercise test with a 15-minute warm-up at an intensity of 60% of the maximal oxygen uptake obtained in the first incremental exercise test and the same test without warm-up.Results. The peak values of physiological variables were statistically significantly higher for the incremental exercise test with warm-up, the differences between tests being 2.66% for peak power output (p = 0.039, t = 2.312, ES = 0.24), 7.75% for peak oxygen uptake (p = 0.000, t = 5.225, ES = 0.56), 7.72% for peak minute ventilation (p = 0.005, t = 3.346, ES = 0.53) and 1.62% for peak heart rate (p = 0.019, t = 2.690, ES = 0.60).Conclusions. Warm-up before a ramp incremental exercise test resulted in higher values of maximal oxygen uptake, maximal minute ventilation, maximal heart rate and peak power output.