Explore the vast range of titles available.

PurposeThe aim of this study was to examine how respiratory (RT) and lactate thresholds (LT) are affected by acute heat exposure in the two most commonly used incremental exercise test protocols (RAMP and STEP) for functional evaluation of aerobic fitness, exercise prescription and monitoring training intensities.MethodsEleven physically active male participants performed four incremental exercise tests, two RAMP (30 W·min−1) and two STEP (40 W·3 min−1), both in 18 °C (TEMP) and 36 °C (HOT) with 40% relative humidity to determine 2 RT and 16 LT, respectively. Distinction was made within LT, taking into account the individual lactate kinetics (LTIND) and fixed value lactate concentrations (LTFIX).ResultsA decrease in mean power output (PO) was observed in HOT at LT (−6.2 ± 1.9%), more specific LTIND (−5.4 ± 1.4%) and LTFIX (−7.5 ± 2.4%), compared to TEMP, however not at RT (−1.0 ± 2.7%). The individual PO difference in HOT compared to TEMP over all threshold methods ranged from −53 W to +26 W. Mean heart rate (HR) did not differ in LT, while it was increased at RT in HOT (+10 ± 8 bpm).ConclusionThis study showed that exercise thresholds were affected when ambient air temperature was increased. However, a considerable degree of variability in the sensitivity of the different threshold concepts to acute heat exposure was found and a large individual variation was noticed. Test design and procedures should be taken into account when interpreting exercise test outcomes.

PurposePeak power output (W˙peak) in an incremental exercise test (EXT) is considered an important predictor of performance for cyclists. However, W˙peak is protocol dependent. The purpose of this study was to model the effect of EXT design on W˙peak.MethodsAn adapted version of a previously developed mathematical model was used. For the purpose of validity testing, we compared predicted W˙peak differences (predicted ΔW˙peak) with actual ΔW˙peak found in sports science literature.ResultsThe model quantified ΔW˙peak between 36 EXT designs with stage durations in the range 1–5 min and increments in the range 10–50 W. Predicted ΔW˙peak and actual ΔW˙peak across a wide range of performance levels of cyclists were in good agreement. Depending on the specific combination of increment and stage duration, W˙peak may be widely different or equivalent. A minimum difference in increment (5 W) or in stage duration (1 min) already results in significantly different W˙peak. In EXTs having the same ratio between increment and stage duration, W˙peak in the EXT with the shortest stage duration or the greatest increment is significantly higher. Tests combining 15 W, 25 W or 40 W increments with 2, 3 and 4 min stage durations, respectively, are ‘special’ in that their W˙peak approximates the power output associated with maximal oxygen uptake (P-V˙O2max).ConclusionsThe modeling results allow comparison of W˙peak between widely different EXT designs. Absolute performance level does not affect ΔW˙peak. W˙peak15/2, W˙peak25/3 and W˙peak40/4 constitute a practical physiologic reference for performance diagnostics and exercise intensity prescription.

The accurate detection of several physiological milestones, such as maximal fat oxidation (MFO), is an important factor for cycling performance and for programming effective and individualised training. However, the procedure to identify the MFO is often too complex and expensive. Near‐infrared spectroscopy (NIRS) technology provides a noninvasive measurement that can be used to detect different physiological variables. The aim of this study was to assess the validity of utilising the muscular oxygen saturation visualisation methodology for the identification of the MFO point in trained cyclists. Twenty‐two recreational endurance‐trained cyclists (19 men and 3 women; age: 27.9 ± 5.4 years; body mass: 69.7 ± 7.1 kg and VO2max: 60.3 ± 7.0 mL/kg/min) performed a submaximal and maximal exhaustion test. All the data were collected on a single day. The validity of the visualisation methodology for the maximal fat oxidation point was analysed against a gas analyser. The detection of maximal fat oxidation (MFO) using the methodology and device employed does not appear to accurately specify the precise point at which MFO occurs (bias = 90 ± 218 s and LOA = 429 s). However, our results indicate that it may be a valid technique for identifying the MFO zone; biases were HR = 4.7 ± 11.9 bpm, VO2 = 1.49 ± 5.7 mL/kg/min and power = 19.5 ± 31.2 W, whereas the concordance coefficients were 0.783, 0.243 and 0.170, respectively. It is not possible to detect MFO using NIRS device. However, it is possible to detect a general zone in which MFO occurs. Highlights The detection of the maximal fat oxidation point using muscle oxygen saturation plotted as a function of time does not appear to accurately specify the precise point at which maximal fat oxidation occurs. It is possible to detect a general zone in which the maximal fat oxidation occurs. Near‐infrared spectroscopy technology is useful for coaches without time to do complicated analyses.

This study aims to explore the role of Skin Sympathetic Nerve Activity (SKNA) in exercise monitoring and the determination of metabolic thresholds, and to verify the reliability of the SKNA Thresholds (SKNATs). During the Ramp Incremental Exercise Test (RIET), aSKNA, HR, and gas metabolic parameters were recorded and analyzed to assess their changes and the feasibility of SKNATs. Results showed that, compared to the baseline, aSKNA significantly increased during RIET (p < 0.001), and decreased after exercise. The first SKNA threshold (SKNAT1) occurred at 43 ± 6% of exercise time, and the second SKNA threshold (SKNAT2) occurred at 76 ± 5%. At SKNAT1, both HR and aSKNA were significantly lower than at the first ventilatory threshold (VT1) (p < 0.05, p < 0.01), while at SKNAT2, all measures except aSKNA were significantly lower than at the second ventilatory threshold (VT2) (p < 0.05). A strong correlation was observed between SKNATs and VTs, with the highest correlation found at VO2 (r = 0.902, p < 0.0001). ICC showed moderate to strong concordance for all parameters at SKNAT1 and VT1, with higher agreement at the second thresholds. Collectively, aSKNA increases with exercise load during RIET and exhibits non‐linear inflection points. SKNATs show strong potential for predicting VTs, representing a promising emerging indicator for determining metabolic thresholds. Skin Sympathetic Nerve Activity as an Exercise Threshold Indicator. During the incremental load exercise, aSKNA exhibits two distinct inflection points with increasing load intensity, forming SKNATs, a novel metabolic threshold based on SKNA.

Cardiorespiratory coupling (CRC) reflects coordination between heart and lung function, but how it changes with increasing intensity during graded exercise remains unclear. We investigated CRC as real‐time covariation between cardiac timing and breath‐by‐breath pulmonary oxygen uptake (VO2) to test whether coupling strengthens with workload in adolescent athletes. We conducted an observational, within‐subject analysis of the ACTES cycling dataset. Eighteen adolescents cycled at 50, 110, and 140 W. Beat‐to‐beat RR intervals and pulmonary VO2 time series were examined in ultra‐short 60 s segments. Fluctuations were summarized using SDRR/RMSSD and SDVO2/RMSSDVO2. CRC was measured using joint symbolic dynamics (JSD; Shannon entropy, SE, and Miller–Madow–corrected entropy, CSE) and the highest normalized cross‐correlation (X‐Corr). Mean RR decreased and mean pulmonary VO2 increased with workload (both p < 0.0001). SDRR and RMSSD were lower at 110 and 140 W versus 50 W; SDVO2 declined from 50 to 110/140 W, whereas RMSSDVO2 was unchanged. X‐Corr increased from 50 to 110/140 W (p ≤ 0.0014). JSD indices decreased as workload increased (SE: global p = 0.139; CSE: global p = 0.029), suggesting tighter CRC. CRC becomes more pronounced with increased workload, aligning with reduced heart rate variability and reflecting vagal withdrawal and reflex responses that improve heart–lung integration in adolescent athletes.

Background: To achieve victory, kayaking and rowing athletes must develop optimal aerobic conditioning and the capacity to sustain anaerobic work production. To assess these characteristics, power output (PO), lactatemia response, and maximum oxygen uptake (VO2max) are usually measured. The goal of this research is to report the values of PO, lactatemia, and VO2max—expressed in relative, absolute, and body size-scaled values—in successful international-level athletes to provide reference values for those striving to compete at the highest level. Methods: A total of 15 international-level medallist boat sports athletes were recruited: 8 male kayakers (age 21 ± 3 years, height 181.7 ± 5.3 cm, body mass 78.7 ± 5.6 kg), 2 female kayakers (age 22 ± 2 years, height 168.0 ± 2.8 cm, body mass 64.9 ± 2.7 kg), and 5 male rowers (age 20 ± 1 years, height 181.9 ± 4.7 cm, body mass 83.9 ± 7.3 kg). The athletes’ PO, lactatemia, and VO2max were assessed using an off-water, sport-specific cardiopulmonary test on a paddle and rowing ergometer. Results: Respectively, in male and female kayakers and male rowers, maximum lactatemia was 11.9 ± 2.2 mmol/L, 9.3 ± 3.6 mmol/L, and 13.2 ± 3.7 mmol/L; maximum PO was 225.0 ± 13.4 W, 162.5 ± 31.8 W and 432.0 ± 33.5 W; and VO2max was 57.6 ± 5.4 mL/min/kg, 52.2 ± 1.0 mL/min/kg, and 63.7 ± 11.7 mL/min/kg. VO2max scaled by body size was, respectively, 311 ± 39 mL/kg0.67/min, 319 ± 15 mL/kg0.67/min, and 330 ± 72 mL/kg0.67/min. Conclusions: This study is the first to report the values of PO, lactatemia, and VO2max—expressed in relative, absolute, and body size-scaled values—assessed during a sport-specific cardiopulmonary test in international-level boat sports athletes. These values could be a preliminary reference guideline for optimal cardiorespiratory conditioning in athletes aiming at international-level competitions.

Treadmill exercise tests assess aerobic capacity in chronic heart failure (CHF) mice, but subjective exhaustion criteria limit reproducibility. Elevated blood lactate (La) at exhaustion may provide an objective fatigue marker. This study evaluated La at exhaustion and the effects of exercise training (ExT) on resting La in CHF mice. Sham and coronary artery ligation‐induced CHF mice were assigned to sedentary (Sed) or ExT groups. Blood La was measured from 0.7 μL tail vein samples at rest and at exhaustion during exercise tests after 8 weeks of ExT. Blood La at rest was slightly higher in CHF‐Sed mice (3.33 ± 1.23 mmol/L) than in Sham‐Sed mice (2.96 ± 0.42 mmol/L; p = 0.86). ExT slightly reduced La in CHF mice (2.55 ± 0.63 mmol/L; p = 0.34 vs. CHF‐Sed), but differences were not significant. At exhaustion, blood La increased significantly across groups. Baseline La in CHF‐Sed mice negatively correlated with running distance (r = −0.84, p = 0.03). Blood La levels at exhaustion offer a cost‐effective method to confirm exhaustion criteria and enhance the reliability of exercise tests. La at rest may not reflect CHF severity or exercise adaptation but correlates better with exercise capacity in CHF.

This study aimed to elucidate whether muscle blood flow restriction during maximal exercise is associated with alterations in hemodynamics, cerebral oxygenation, cerebral activation, and deterioration of exercise performance in male participants. Thirteen healthy males, cyclists (age 33 ± 2 yrs., body mass: 78.6 ± 2.5 kg, and body mass index: 25.57 ± 0.91 kg·m−1), performed a maximal incremental exercise test on a bicycle ergometer in two experimental conditions: (a) with muscle blood flow restriction through the application of thigh cuffs inflated at 120 mmHg (with cuffs, WC) and (b) without restriction (no cuffs, NC). Exercise performance significantly deteriorated with muscle blood flow restriction, as evidenced by the reductions in V˙O2max (−17 ± 2%, p < 0.001), peak power output (−28 ± 2%, p < 0.001), and time to exhaustion (−28 ± 2%, p < 0.001). Muscle oxygenated hemoglobin (Δ[O2Hb]) during exercise declined more in the NC condition (p < 0.01); however, at exhaustion, the magnitude of muscle oxygenation and muscle deoxygenation were similar between conditions (p > 0.05). At maximal effort, lower cerebral deoxygenated hemoglobin (Δ[HHb]) and cerebral total hemoglobin (Δ[THb]) were observed in WC (p < 0.001), accompanied by a lower cardiac output, heart rate, and stroke volume vs. the NC condition (p < 0.01), whereas systolic blood pressure, rating of perceived exertion, and cerebral activation (as assessed by electroencephalography (EEG) activity) were similar (p > 0.05) between conditions at task failure, despite marked differences in exercise duration, maximal aerobic power output, and V˙O2max. In conclusion, in trained cyclists, muscle blood flow restriction during an incremental cycling exercise test significantly limited exercise performance. Exercise intolerance with muscle blood flow restriction was mainly associated with attenuated cardiac responses, despite cerebral activation reaching similar maximal levels as without muscle blood flow restriction.

Self-paced exercise protocols have gained attention for their potential to optimize performance and manage fatigue by allowing individuals to regulate their efforts based on perceived exertion. This pilot study aimed to investigate the neural and physiological responses during a self-paced V˙O2max (SPV) and incremental exercise tests (IET). Six trained male cyclists (mean age 39.2 ± 13.3 years; V˙O2max 54.3 ± 8.2 mL·kg−1·min−1) performed both tests while recording their brain activity using electroencephalography (EEG). The IET protocol involved increasing the power every 3 min relative to body weight, while the SPV allowed participants to self-regulate the intensity using ratings of perceived exertion (RPE). Gas exchange, EEG, heart rate (HR), stroke volume (SV), and power output were continuously monitored. Statistical analyses included a two-way repeated measures ANOVA and Wilcoxon signed-rank tests to assess differences in alpha and beta power spectral densities (PSDs) and the EEG/V˙O2 ratio. Our results showed that during the SPV test, the beta PSD initially increased but stabilized at around 80% of the test duration, suggesting effective management of effort without further neural strain. In contrast, the IET showed a continuous increase in beta activity, indicating greater neural demand and potentially leading to an earlier onset of fatigue. Additionally, participants maintained similar cardiorespiratory parameters (V˙O2, HR, SV, respiratory frequency, etc.) across both protocols, reinforcing the reliability of the RPE scale in guiding exercise intensity. These findings suggest that SPV better optimizes neural efficiency and delays fatigue compared to fixed protocols and that individuals can accurately control exercise intensity based on perceived exertion. Despite the small sample size, the results provide valuable insights into the potential benefits of self-paced exercise for improving adherence to exercise programs and optimizing performance across different populations.

Context: \"Surya Namaskar\" (SN) may be used as a need-based short-duration aerobic activity in a confined space to establish as a substitute of an equivalent routine physical training in challenging stressful conditions. Materials and Methods: Noninvasive oxygen-kinetics metabolic responses between SN and endurance work on bicycle ergometry (BE) were compared across different phases of maximal oxygen uptake percentage (%VO2 max). SN, comprising three complete rounds per min (36 beats/min of a metronome; SN consists of 12 poses per round), was performed rhythmically and continuously for 5 min to simulate an incremental BE test (25 watts/2 min at 60 rpm). Results: SN results in a significant (P < 0.05) greater increase of arteriovenous oxygen difference at 71%-80% VO2 max while keeping a low respiratory exchange ratio (P < 0.01 and 0.001) at 41%-80% VO2 max exercising state. Conclusions: SN could be an ideal form of aerobic exercise instead of BE.