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The benefits of altitude/hypoxic training for sea level performance are still under debate. This study examined the effects of low altitude training supported by normobaric hypoxia on hematological status and endurance performance predictors in elite female cyclists. Twenty-two female cyclists trained for 3 weeks at low altitude (<1100 m) and 2 weeks near sea level. During the first 3 weeks, 15 subjects stayed in hypoxic rooms simulating an altitude of 2200 m (+NH group, = 8) or 1000 m (placebo group, = 7), and 7 (control group) stayed in regular rooms. Significant increases in total hemoglobin mass (tHb-mass: p = 0.008, p = 0.025), power at 4 mmol·l lactate (PAT4: p = 0.004, p = 0.005) (in absolute and relative values, respectively) and maximal power (PF: p = 0.034) (in absolute values) were observed. However, these effects were not associated with normobaric hypoxia. Changes in tHb-mass were not associated with initial concentrations of ferritin or transferrin receptor, whereas changes in relative tHb-mass (r = -0.53, p = 0.012), PF (r = -0.53, p = 0.01) and PAT4 (r = -0.65, p = 0.001) were inversely correlated with initial values. Changes in tHb-mass and PAT4 were positively correlated (r = 0.50, p = 0.017; r = 0.47, p = 0.028). Regardless of normobaric hypoxia application, low altitude training followed by sea-level training might improve hematological status in elite female cyclists, especially with relatively low initial values of tHb-mass, which could translate into enhanced endurance performance.

This study explored the impact of circadian rhythms on the circulating cardiac troponin T (cTnT) response to a graded exercise test (GXT) and examined whether an initial GXT influenced the cTnT response to a subsequent GXT performed 7–9 days later. Twenty‐one healthy young males (age: 20.6 ± 2.2 years, body mass index: 22.2 ± 2.6 kg/m2, V̇O2max: 31.8 ± 8.7 mL.kg−1.min−1) participated in three trials: an initial GXT (GXT1), a resting control trial (CON) and a second GXT (GXT2), separated by at least 72 h. The serum cTnT levels were measured pre‐exercise, 4 h post‐exercise or during the control. In GXT1, the cTnT levels did not show significant changes (median [range], pre: 3.80 [3.00–10.59] ng.L−1, post: 4.22 [3.00–9.08] ng.L−1, p > 0.05). During CON, the cTnT levels decreased significantly from morning to early afternoon (3.52 [3.00–10.84] vs. 3.00 [3.00–7.57] ng.L−1, p < 0.05), reflecting a circadian rhythm. Interestingly, GXT1 appeared to prevent this circadian decline. Furthermore, in GXT2, the cTnT levels significantly decreased post‐exercise (4.13 [3.00–15.48] vs. 3.24 [3.00–12.96] ng.L−1, p < 0.05), suggesting a possible “late exercise preconditioning” effect from GXT1. These findings suggest that GXT can interact with circadian rhythms, altering cTnT dynamics, and that prior exercise may induce prolonged cardioprotective effects. This study highlights the importance of accounting for circadian variability and late preconditioning effects in future research on exercise‐induced cTnT release.

This study characterizes high-altitude training camps and their effect on the aerobic capacity of a Polish national team member (M.W.), who was a participant in the PyeongChang 2018 Winter Olympic Games (body weight: 59.6 kg, body height: 161.0 cm, fat mass: 10.9 kg and 18.3% of fat tissue, fat-free mass: 48.7 kg, muscle mass: 46.3 kg, and BMI = 23.0 kg/m2). The tests were conducted in the periods from April 2018 to September 2018 and April 2019 to September 2019 (period of general and special preparation). The study evaluated aerobic and anaerobic capacity determined by laboratory tests, a cardiopulmonary graded exercise test to exhaustion performed on a cycle ergometer (CPET), and the Wingate anaerobic test. Based on the research, training in hypobaric conditions translated into significant improvements in the skater’s exercise capacity recorded after participating in the Olympic Winter Games in Korea (February 2018). In the analyzed period (2018–2019), there was a significant increase in key parameters of aerobic fitness such as anaerobic threshold power output (AT-PO) [W]—223; power output POmax [W]—299 and AT-PO [W/kg]—3.50; (POmax) [W/kg]—4.69; and AT-VO2 [mL/kg/min]—51.3; VO2max [mL/kg/min]—61.0. The athlete showed high-exercise-induced adaptations and improvements in the aerobic metabolic potential after two seasons, in which four training camps were held in altitude conditions.

The maximal lactate steady state, abbreviated as MLSS, is the maximal exercise intensity where the concentration of earlobe capillary or arterial blood lactate remains constant over time. In the late 1970s and early 1980s, we (i.e. Hermann Heck and co-workers) developed a direct test to determine the MLSS to investigate whether it occurred at a lactate concentration of 4 mmol.L − 1 , as earlier predicted by Alois Mader and colleagues. The test consisted of each participant performing several constant-intensity running bouts of ≈ 30 min at intensities close to the estimated MLSS. During each run, we measured lactate every 5 min. Based on the results, we defined the MLSS as the “ workload where the concentration of blood lactate does not increase more than 1 mmo . L − 1 during the last 20 min of a constant load exercise ”. This MLSS protocol is impractical for performance testing as it requires too many exercise bouts, but it is a gold standard to determine the real MLSS. It is especially useful to validate indirect tests that seek to estimate the MLSS.

The primary purpose of the present study was to re-visit HRmax prediction by two commonly used equations (i.e., Fox′s and Tanaka′s equation) compared to the direct measured HRmax using the large sample size of Asians. The second aim of the study was to focus on suggesting new equations for the Asian population by separating gender and specific age groups. A total of 672 participants aged from 7 to 55 years were recruited for the study (male: 280 and female: 392), and the maximal graded exercise test with Bruce protocol was used to measure HRmax. All data obtained from the study were analyzed by SPSS 25.0. Additionally, three statistical analysis methods (i.e., Mean Absolute Percent Errors (MAPE), Bland–Altman plots, and equivalence testing) were utilized to confirm the consistency between the measured HRmax and the two prediction equations. The main finding was that two equations showed significant differences in predicting the HRmax of Korean aged from 7 to 55 years. The outcome of children aged from 7 to 14 was a different fit in the agreement compared to other age groups. Fox′s equation had the best fit in the average of the difference closer to zero and completely included within the equivalence zone, but females over 15 years old revealed higher errors than males in the values calculated by the two equations compared to the direct measured HRmax. Consequently, the study demonstrated that both equations tended to overestimate the HRmax for males and females over 15 years old, and the two universal equations were not suitable to predict the HRmax of Koreans except for children aged from 7 to 14 years. The new HRmax prediction equations suggested in this study will more accurately predict the HRmax of Asians, and additional analyses should be examined the cross-validity of the developed HRmax equation by age and gender in the future study.

This study compared exercise performance and comfort while wearing an N95 filtering facepiece respirator (N95), cloth mask, or no intervention control for source control during a maximal graded treadmill exercise test (GXT). Twelve Division 1 athletes (50% female, age = 20.1 ± 1.2, BMI = 23.5 ± 1.6) completed GXTs under three randomized conditions (N95, cloth mask, control). GXT duration, heart rate (HR), respiration rate (RR), transcutaneous oxygen saturation (SpO2), transcutaneous carbon dioxide (TcPCO2), rating of perceived exertion (RPE), and perceived comfort were measured. Participants ran significantly longer in control (26.06 min) versus N95 (24.20 min, p = 0.03) or cloth masks (24.06 min, p = 0.04). No differences occurred in the slope of HR or SpO2 across conditions (p > 0.05). TcPCO2 decreased faster in control (B = −0.89) versus N95 (B = 0.14, p = 0.02) or cloth masks (B = −0.26, p = 0.03). RR increased faster in control (B = 8.32) versus cloth masks (B = 6.20, p = 0.04). RPE increased faster in the N95 (B = 1.91) and cloth masks (B = 1.79) versus control (B = 1.59, p < 0.001 and p = 0.05, respectively). Facial irritation/itching/pinching was higher in the N95 versus cloth masks, but sweat/moisture buildup was lower (p < 0.05 for all). Wearing cloth masks or N95s for source control may impact exercise performance, especially at higher intensities. Significant physiological differences were observed between cloth masks and N95s compared to control, while no physiological differences were found between cloth masks and N95s; however, comfort my differ.

Six-minute walk test (6MWT) performance is more commonly used in clinic patients with chronic cardiopulmonary diseases but not in home-dwelling individuals of similar age, and its correlations with oxygen uptake (VO2) and muscle strength require further investigation. The current study determined the 6MWT performance of 106 home-dwelling residents (mean age of 62 years) in Suzhou, China. VO2 at a respiratory exchange ratio (R) of 1 was measured through graded cycling exercise tests on 46 participants. Handgrip strength of all participants was tested. 6MWT distance measured 543.4 ± 67.2 m (total work 351.0 ± 62.8 kJ) with similar distances ambulated each minute. Heart rate, blood pressure, and rate of perceived exertion scores significantly increased after 6MWT. VO2 at R = 1 reached 1238 ± 342 mL/min (18.6 ± 4.7 mL/kg/min), whereas handgrip strength totaled 29.8 ± 9.6 kg. 6MWT distance showed strong correlations with VO2 (r = 0.549, p ≤ 0.001) and handgrip strength (r = 0.359, p < 0.001). Aside from providing reference values for 6MWT performance (~543 m, ~559 m in males and ~533 in females) for home-dwelling Chinese residents, our results suggest that as a parameter of exercise endurance, 6MWT performance correlates with both aerobic capacity and muscle fitness.

The purpose of the study was to examine the effects of altering from habitual mixed Western-based (HD) to a very low-carbohydrate high-fat (VLCHF) diet over a 4-week timecourse on performance and physiological responses during high-intensity interval training (HIIT). Eighteen moderately trained males (age 23.8 ± 2.1 years) consuming their HD (48 ± 13% carbohydrate, 17 ± 3% protein, 35 ± 9% fat) were assigned to 2 groups. One group was asked to remain on their HD, while the other was asked to switch to a non-standardized VLCHF diet (8 ± 3% carbohydrate, 29 ± 15% protein, 63 ± 13% fat) for 4 weeks. Participants performed graded exercise tests (GXT) before and after the experiment, and an HIIT session (5x3min, work/rest 2:1, passive recovery, total time 34min) before, and after 2 and 4 weeks. Heart rate (HR), oxygen uptake ( O ), respiratory exchange ratio (RER), maximal fat oxidation rates (Fat ) and blood lactate were measured. Total time to exhaustion (TTE) and maximal O (V̇O ) in the GXT increased in both groups, but between-group changes were (ES ± 90% CI: -0.1 ± 0.3) and (0.57 ± 0.5), respectively. Between-group difference in Fat change (VLCHF: 0.8 ± 0.3 to 1.1 ± 0.2 g/min; HD: 0.7 ± 0.2 to 0.8 ± 0.2 g/min) was (1.2±0.9), revealing greater increases in the VLCHF versus HD group. Between-group comparisons of mean changes in V̇O and HR during the HIIT sessions were to , whereas mean RER decreased more in the VLCHF group (-1.5 ± 0.1). Lactate changes between groups were . Adoption of a VLCHF diet over 4 weeks increased Fat and did not adversely affect TTE during the GXT or cardiorespiratory responses to HIIT compared with the HD.

PurposeThis study compared cardio-pulmonary responses between incremental concentric and eccentric cycling tests, and examined factors affecting the maximal eccentric cycling capacity.MethodsOn separate days, nine men and two women (32.6 ± 9.4 years) performed an upright seated concentric (CON) and an eccentric (ECC) cycling test, which started at 75 W and increased 25 W min−1 until task failure. Gas exchange, heart rate (HR) and power output were continuously recorded during the tests. Participants also performed maximal voluntary contractions of the quadriceps (MVC), squat and countermovement jumps.ResultsPeak power output was 53% greater (P < 0.001, g = 1.77) for ECC (449 ± 115 W) than CON (294 ± 61 W), but peak oxygen consumption was 43% lower (P < 0.001, g = 2.18) for ECC (30.6 ± 5.6 ml kg min−1) than CON (43.9 ± 6.9 ml kg min−1). Maximal HR was not different between ECC (175 ± 20 bpm) and CON (182 ± 13 bpm), but the increase in HR relative to oxygen consumption was 33% greater (P = 0.01) during ECC than CON. Moderate to strong correlations (P < 0.05) were observed between ECC peak power output and CON peak power (r = 0.84), peak oxygen consumption (r = 0.54) and MVC (r = 0.53), while no significant relationships were observed between ECC peak power output and squat as well as countermovement jump heights.ConclusionUnexpectedly, maximal HR was similar between CON and ECC. Although ECC power output can be predicted from CON peak power output, an incremental eccentric cycling test performed after 3–6 familiarisation sessions may be useful in programming ECC training with healthy and accustomed individuals.

Background/Objectives: Long-distance runners with exercise-induced hypertension (EIH) are at increased risk for cardiovascular complications. Although blood flow restriction (BFR) training has shown promise in improving vascular function, hemodynamic response, and cardiorespiratory fitness, its effects in EIH runners remain understudied. This study aimed to evaluate the effects of BFR training on cardiovascular responses and exercise performance in this population as a potential non-pharmacological therapy. Methods: Middle-aged male long-distance runners aged 40–65 with peak systolic blood pressure (SBP) ≥ 210 mmHg during graded exercise testing were randomly assigned to either a BFR group (n = 18) or a non-BFR control group (n = 15) using a computer-generated random sequence. There were no significant differences in baseline characteristics between the groups. Both groups performed aerobic training at 40–60% HRR for 20 min twice weekly for 8 weeks. SBP, diastolic blood pressure (DBP), rate pressure product (RPP), ventilatory threshold (VT), VO₂max, and perceived exertion were assessed before and after the intervention at rest, during exercise, and during recovery. Results: Compared to the non-BFR group, the BFR group showed statistically significant reductions in resting and maximal SBP and DBP (p < 0.05), along with significant increases in VO₂max and VT (p < 0.05). During submaximal exercise and post-exercise recovery, SBP and RPP were significantly lower in the BFR group (p < 0.05). The reductions in maximal SBP and DBP were significantly greater in the BFR group than in the control group. Conclusions: BFR training led to reduced myocardial workload and enhanced cardiovascular efficiency in male runners with EIH. These findings suggest that BFR training may be a viable non-pharmacological therapy for mitigating cardiovascular risks associated with EIH. Future studies should explore the long-term effects of BFR in broader populations and assess its applicability in clinical settings.