Maximal Incremental Cycling Test Research Articles

Detrended fluctuation analysis to determine physiologic thresholds, investigation and evidence from incremental cycling test.

Training zones are generally assessed by gas-exchange thresholds (GET). Several mathematical analyses of heart rate variability (HRV) are proposed for indirect GET determination. Our study aimed to investigate the accordance of the detrend fluctuation analysis (DFA α1) for determining GET with first (VT1) and second ventilatory (VT2) thresholds in well-trained subjects. Eighteen female and 38 male sub-elite cyclists performed a maximal incremental cycling test of 2-min stage duration with continuous gas exchange and HR measurements. Power output (PO), Oxygen uptake ( O2) and HR at VT1 and VT2 were compared with DFA α1 0.75 (HRVT1) and 0.50 (HRVT2). Agreements between PO, O2 and HR values were analyzed using Bland-Altman analysis. Large limits of agreement between VT1 and HRVT1 were observed for measures of O2 expressed in mL.min-1.kg-1 [-21.3; + 14.1], HR [39.2; + 26.9] bpm and PO [-118; + 83] watts. Indeed, agreements were also low between VT2 and HRVT2 for measures of O2 [-26.7; + 4.3] mL.min-1.kg-1, HR [-45.5; + 10.6] bpm and PO [-157; + 35] watts. Our results also showed a sex effect: women obtained worst predictions based on DFA α1 than men for HR (p = 0.014), PO (p = 0.044) at VT1 and (p = 0.045), HR (p = 0.003) and PO (p = 0.004) at VT2. There was unsatisfactory agreement between the GET and DFA α1 methods for VT1 and VT2 determination in both sex well-trained cyclists. Trial registrationnumber 2233534 on 2024/03/05 retrospectively registered.

Difference in expiratory flow limitations development in normoxia and hypoxia in healthy individuals

The present study investigated the maintenance/repeatability of expiratory flow limitation (EFL) between normoxia and hypoxia.Fifty-one healthy active individuals (27 men and 24 women) performed a lung function test and a maximal incremental cycling test in both normoxia and hypoxia (inspired oxygen fraction = 0.14) on two separate visits.During exercise in normoxia, 28 participants exhibited EFL (55 %). In hypoxia, another cohort of 28 participants exhibited EFL. The two groups only partly overlapped.Individuals with EFL only in normoxia reported lower maximal ventilation values in hypoxia than in normoxia (n=5; −13.5 ± 7.8 %) compared to their counterparts with EFL only in hypoxia (n=5; +6.7 ± 6.3 %) or without EFL (n=18; +5.1 ± 10.3 %) (p=0.004 and p<0.001, respectively).EFL development may be induced by different mechanisms in hypoxia vs. normoxia since the individuals who exhibited flow limitation were not the same between the two environmental conditions. This change seems influenced by the magnitude of the maximal ventilation change.

The 2-Minutes Walking Test Is Not Correlated with Aerobic Fitness Indices but with the 5-Times Sit-to-Stand Test Performance in Apparently Healthy Older Adults.

The 2-minutes walking test (2-MWT) is a valid and reliable test that has a high correlation with the distance walked in the 6-minutes walking test (6-MWT). However, to date, no study has determined the relationship between 2-MWT performance and the aerobic fitness indices obtained during a maximal incremental test to confirm if this test is a valid surrogate of aerobic fitness in apparently healthy older adults. The main objective of this work was to identify the factors associated to the performance in the 2-MWT, including aerobic fitness, functional and spatial-temporal gait parameters. Seventeen elderly adults performed a maximal incremental cycling test to determine maximum oxygen consumption (VO2max) and ventilatory thresholds (VT1 and VT2), two static standing balance tests with open and close eyes, a 5-times sit-to-stand test (5-TSTS), a handgrip test, and a 2-MWT on three different days over 2 weeks. No correlations were found between aerobic fitness indices and the distance covered in 2-MWT, but significant moderate correlations were found between the distance covered in 2-MWT and the time to perform the 5-TSTS (rho = -0.49) and with stride length (rho = 0.52) during the test. In conclusion, the 2-MWT does not seem a good test to assess aerobic capacity while it showed to be associated to the 5-TSTS performance of the elderly.

Fitness Level- and Sex-Related Differences in Pulmonary Limitations to Maximal Exercise in Normoxia and Hypoxia.

Both maximal-intensity exercise and altitude exposure challenge the pulmonary system that may reach its maximal capacities. Expiratory flow limitation (EFL) and exercise-induced hypoxemia (EIH) are common in endurance-trained athletes. Furthermore, because of their smaller airways and lung size, women, independently of their fitness level, may be more prone to pulmonary limitations during maximal-intensity exercise, particularly when performed in hypoxic conditions. The objective of this study was to investigate the impact of sex and fitness level on pulmonary limitations during maximal exercise in normoxia and their consequences in acute hypoxia. Fifty-one participants were distributed across four different groups according to sex and fitness level. Participants visited the laboratory on three occasions to perform maximal incremental cycling tests in normoxia and hypoxia (inspired oxygen fraction = 0.14) and two hypoxic chemosensitivity tests. Pulmonary function and ventilatory capacities were evaluated at each visit. EIH was more prevalent (62.5% vs 22.2%, P = 0.004) and EFL less common (37.5% vs 70.4%, P = 0.019) in women than men. EIH prevalence was different ( P = 0.004) between groups of trained men (41.7%), control men (6.7%), trained women (50.0%), and control women (75.0%). All EIH men but only 40% of EIH women exhibited EFL. EFL individuals had higher slope ratio ( P = 0.029), higher ventilation (V̇ E ) ( P < 0.001), larger ΔVO 2max ( P = 0.019), and lower hypoxia-related V̇ E increase ( P < 0.001). Women reported a higher EIH prevalence than men, regardless of their fitness level, despite a lower EFL prevalence. EFL seems mainly due to the imbalance between ventilatory demands and capacities. It restricts ventilation, leading to a larger performance impairment during maximal exercise in hypoxic conditions.

The effects of age on dyspnea and respiratory mechanical and neural responses to exercise in healthy men.

The respiratory muscle pressure generation and inspiratory and expiratory neuromuscular recruitment patterns in younger and older men were compared during exercise, alongside descriptors of dyspnea. Healthy younger (n = 8, 28 ± 5 years) and older (n = 8, 68 ± 4 years) men completed a maximal incremental cycling test. Esophageal, gastric (Pga ) and transdiaphragmatic pressures, and electromyography (EMG) of the crural diaphragm were measured using a micro-transducer and EMG catheter. EMG of the parasternal intercostals, sternocleidomastoids, and rectus abdominis were measured using skin surface electrodes. After the exercise test, participants completed a questionnaire to evaluate descriptors of dyspnea. Pga at end-expiration, Pga expiratory tidal swings, and the gastric pressure-time product (PTPga ) at absolute and relative minute ventilation were higher (p < 0.05) for older compared to younger men. There were no differences in EMG responses between older and younger men. Younger men were more likely to report shallow breathing (p = 0.005) than older men. Our findings showed younger and older men had similar respiratory neuromuscular activation patterns and reported different dyspnea descriptors, and that older men had greater expiratory muscle pressure generation during exercise. Greater expiratory muscle pressures in older men may be due to compensatory mechanisms designed to offset increasing airway resistance due to aging. These results may have implications for exercise-induced expiratory muscle fatigue in older men.

Oxygen uptake ( O2) and pulmonary ventilation ( E) during military surface fin swimming in a swimming flume: Effects of surface immersion.

Introduction: During military fin swimming, we suspected that oxygen uptake ( O2) and pulmonary ventilation ( E) might be much higher than expected. In this framework, we compared these variables in the responses of trained military divers during land cycling and snorkeling exercises. Methods: Eighteen male military divers (32.3 ± 4.2years; 178.0 ± 5.0cm; 76.4 ± 3.4kg; 24.1 ± 2.1kgm-2) participated in this study. They performed two test exercises on two separate days: a maximal incremental cycle test (land condition), and an incremental fin swimming (fin condition) in a motorized swimming flume. Results: The respective fin and land O2max were 3,701 ± 39mLmin-1 and 4,029 ± 63mLmin-1 (p = 0.07), these values were strongly correlated (r 2 = 0.78 p < 0.01). Differences in O2max between conditions increased relative to l; O2max (r 2 = 0.4 p = 0.01). Fin E max values were significantly lower than land E max values (p = 0.01). This result was related to both the significantly lower fin Vt and f (p < 0.01 and <0.04, respectively). Consequently, the fin E max / O2max ratios were significantly lower than the corresponding ratios for land values (p < 0.01), and the fin and land E max were not correlated. Other parameters measured at exhaustion-PaO2, PaCO2, and SO2 - were similar in fin and land conditions. Furthermore, no significant differences between land and fin conditions were observed for peak values for heart rate, blood lactate concentration, and respiratory exchange ratio R. Conclusion: Surface immersion did not significantly reduce the O2max in trained divers relative to land conditions. As long as O2 remained below O2max , the E values were identical in the two conditions. Only at O2max was E higher on land. Although reduced by immersion, E max provided adequate pulmonary gas exchange during maximal fin swimming.

Laboratory-based determinants of simulated time trial performance in cyclists.

Different laboratory-based variables are individually associated with cycling performance, but scarce evidence exists on which of them, when all assessed in combination, could best explain cycling performance. The present study aimed to examine the combined association between laboratory-based endurance, strength/power and body composition indicators with time trial performance in high-level cyclists. Ninety-four male cyclists were recruited (age: 20 ± 3.5 years, maximum oxygen uptake [V̇O2max]: 77.7 ± 5.4 ml · kg-1 · min-1). Participants performed a maximal incremental cycling test for the assessment of endurance indicators (peak power output [PPO], V̇O2max, ventilatory threshold [VT] and respiratory compensation point [RCP]), and an incremental loading test to assess muscle strength and power-related outcomes (1-repetition maximum, mean maximal power) in the squat, lunge and hip-thrust exercises. Body composition was assessed by dual energy X-ray absorptiometry. On a separate visit, participants performed a simulated 8-minute time trial to assess cycling performance (determined as the mean power output attained). Strong-to-very-strong correlations were found between all endurance indicators and time trial performance (most r-values ranging between 0.68-0.92), whereas weaker correlations were found for strength/power (r-values < 0.5) or body composition (r-values < 0.7) indicators. Multivariate regression analyses revealed that VT, RCP and PPO explained together 92% of the variance in time trial performance (p < 0.001), with no significant contribution of the remaining variables. Although different endurance, strength/power and body composition individually correlate with simulated time trial performance in high-level cyclists, the former (and particularly VT, RCP and PPO) show the strongest association when all studied in combination. These findings underscore the importance of endurance capabilities (above strength/power or body composition) for maximizing time trial performance.

Durability in Professional Cyclists: A Field Study.

To assess durability in professional cyclists, as well as potential associated indicators. Twelve male professional cyclists participated in the study (age: 26 [5]y, VO2max: 83.0 [3.6]mL·kg-1·min-1). They performed a 20-minute time trial (TT) on 2 different sessions separated by a 48-hour period: (1)with no previous fatigue (TTFresh) and (2)immediately after a long submaximal ride (approximately 4h, 40kJ/kg) (TTFatigue). We then assessed the decay (in percentage) in mean power output (PO) from TTFresh to TTFatigue and its association with different laboratory-based endurance indicators (ventilatory threshold, peak PO, and VO2max) determined through a previous maximal incremental cycling test, as well as with training loads during the 4 weeks preceding the TTs. While no differences were noted in the average heart rate (177 [7] vs 176 [6] beats·min-1, P = .118), there was a significant decay in PO between TTFresh and TTFatigue (386 [29]W vs 375 [28]W [-2.9%], respectively; P = .007), albeit with signs of interindividual variability (range = -8.5% to 1.1%; coefficient of variation = 105%). No significant associations were found between the PO decay and any of the analyzed indicators (all P > .05). Performance is significantly impaired after a certain amount of work completed (approximately 40kJ·kg-1) in professional cyclists, and the magnitude of this impairment seems to be not related to "traditional" laboratory-based endurance indicators or to markers of training load. These findings might support the need for specifically assessing durability in cyclists and confirming potential determinants of this parameter.

Surgical shortening of lengthened iliac arteries in endurance athletes: Short-term and long-term satisfaction

ObjectiveEndurance athletes are prone to develop flow limitations in iliac arteries (FLIA). Especially in cyclists and ice speed skaters, excessive hemodynamic loading coupled with hip hyperflexion may cause kinking in lengthened iliac arteries necessitating surgical correction. This study investigated the short-term (≤1.5 years) and long-term (≥5 years) satisfaction of operative shortening of the iliac artery in endurance athletes. MethodsAll patients who were diagnosed and operated for FLIA owing to lengthened and kinked iliac arteries between 1997 and 2015 in one center were analyzed. Short-term follow-up consisted of an incremental maximal cycling test, ankle-brachial index with flexed hips, echo-Doppler examination with peak systolic velocity measurements and contrast-enhanced magnetic resonance angiography before and 6 to 18 months after surgery. Both short- and long-term satisfaction were assessed using questionnaires. ResultsA total of 83 patients (90 operated legs; 96.7% males; median age of 34 years at the time of surgery; interquartile range [IQR], 29-47) were analyzed. In the short-term, 87.5% reported symptom reduction with an 86.4% overall satisfaction rate. Symptom-free cycling improved from 272 ± 84 W to 384 ± 101 W (P < .001), whereas the maximal workload increased from 419 ± 72 W to 428 ± 67 W (P = .01). The ankle-brachial index with flexed hips increased from 0.55 (IQR, 0.45-0.65) to 0.62 (IQR, 0.52-0.74; P = .008), and the peak systolic velocity measured with hips flexed decreased from 2.50 m/s (IQR, 1.77-3.13 m/s) to 1.57 m/s (IQR, 1.20-2.04 m/s; P < .001). After a median of 12 years (IQR, 9.0-15.4 years), symptoms were still decreased in 84.1% of patients with an 81.2% overall satisfaction rate (79.5% response rate). Three patients needed a reintervention (recurrent FLIA, n = 2; failure, n = 1). ConclusionsOperative shortening of a lengthened and kinked iliac artery causing FLIA is successful both in the short- and long-term.

Intensified training before Olympic-distance triathlon in recreational triathletes: "Less pain, more gain".

To examine 1) the contribution of physiological performance variables to Olympic-distance (OD) triathlon performance, and 2) the links between an 8-wk intensified training plus competition preceding the main OD triathlon race and the changes in the physiological status in triathletes. An observational longitudinal study. Endurance performance variables during maximal incremental running and cycling tests, and average velocity during an all-out 400-m swimming performance test (V400) were assessed before (T1) and after (T2) the intensified training in 7 recreational-level triathletes. Overall main OD triathlon time was extremely largely (r = -0.94; P = 0.01) correlated with peak running velocity (PRV). Best correlation magnitude between exercise modes' partial race times and the corresponding specific physiological criterion tests was observed for swimming (r = -0.97; P<0.001). Improvement in V400 (2.9%), PRV (1.5%) and submaximal running blood lactate concentration (17%) was observed along the training period, whereas no changes were observed in the cycling endurance performance variables. Higher volume of training plus competition at high intensity zones during cycling, running and swimming were associated with lower improvements or declines in their corresponding exercise mode-specific criterion performance variables (r = 0.81-0.90; P = 0.005-0.037). Results indicate that: 1) PRV is highly associated with overall OD triathlon performance, and 2) spending much time at high relative intensities during swimming, cycling or running may lead, in a dose-response manner, to lower improvements or decreases on those exercise-specific physiological performance variables. This may favor the emergence of overreaching or diminished performance.

High‐intensity Interval Training Combined With Blood‐flow Restriction Predominantly Alters Anaerobic Capacity in Endurance‐trained Athletes

Blood‐flow restriction (BFR) training has gained popularity amongst athletes and sport practitioners to enhance training adaptations and performance. However, BFR has typically been associated with low‐intensity exercise, and there is still limited evidence of its impact when combined with high‐intensity training. This study investigated the impact of high‐intensity interval training (HIIT) with concurrent BFR on anaerobic and aerobic physical capacities and key physiological responses. In a pre‐post, parallel‐groups design, fifteen endurance‐trained males (VO2max 65.0±4.8 mL/min/kg) included three sessions of HIIT per week (sets of 15 s ON/15 s OFF at 100% maximal aerobic power) into their usual training for three weeks either with (BFR group, n=9) or without restriction (CTL group, n=6). In BFR, cuffs were worn proximal on both quadriceps and inflated progressively from 50 to 70% of arterial occlusion pressure across training weeks. Before and after training, athletes completed a maximal incremental step cycling test, a Wingate anaerobic test (WAnT) and a 5‐km cycling time trial. Blood samples were drawn during the time trials. Maximal aerobic power increased in BFR (364.8±60.7 vs 383.4±61.4 watts, p=0.003, Cohen’s effect size ES 0.27) but not in CTL (381.2±62.1 vs 385.5±64.4 watts, p=0.45, ES 0.05). Concomitantly, mean power output achieved during the WAnt also increased with BFR (23.8±4.0 vs 24.6±4.1 kJ, p=0.08, ES 0.28) but not in CTL (23.4±2.5 vs 23.4±2.4 kJ, p=0.95, ES 0.01). However, there was no change between groups in VO2max (BFR: 0.86% vs CTL: 1.77%, ES ‐0.15) and in both the mean power output (BFR: 1.81% vs CTL: 6.51%, ES ‐0.21) and completion time (BFR: ‐0.69% vs CTL: ‐2.55%, ES ‐0.21) of the 5‐km time trial. During the time trial, BFR also induced greater changes in pH (BFR: ‐0.05 vs CTL: ‐0.03 units, ES ‐0.43) and base excess (BFR: ‐1.55 vs CTL: ‐0.70 units, ES ‐0.37), and lowered the potassium ion concentration (BFR: ‐0.55 vs CTL: 0.44 mmol/L, ES ‐0.63). There was no change between groups in lactate production from pre‐ to post‐training. These findings suggest that short‐term HIIT combined with BFR improved anaerobic capacity in endurance‐trained athletes without meaningful effect on endurance exercise performance.

Aerobic Fitness Is Associated with Cerebral μ-Opioid Receptor Activation in Healthy Humans.

Central μ-opioid receptors (MORs) modulate affective responses to physical exercise. Individuals with higher aerobic fitness report greater exercise-induced mood improvements than those with lower fitness, but the link between cardiorespiratory fitness and the MOR system remains unresolved. Here we tested whether maximal oxygen uptake (V̇O2peak) and physical activity level are associated with cerebral MOR availability and whether these phenotypes predict endogenous opioid release after a session of exercise. We studied 64 healthy lean men who performed a maximal incremental cycling test for V̇O2peak determination, completed a questionnaire assessing moderate-to-vigorous physical activity (MVPA; in minutes per week), and underwent positron emission tomography with [11C]carfentanil, a specific radioligand for MOR. A subset of 24 subjects underwent additional positron emission tomography scan also after a 1-h session of moderate-intensity exercise and 12 of them also after a bout of high-intensity interval training. Higher self-reported MVPA level predicted greater opioid release after high-intensity interval training, and both V̇O2peak and MVPA level were associated with a larger decrease in cerebral MOR binding after aerobic exercise in the ventral striatum, orbitofrontal cortex, and insula. That is, more trained individuals showed greater opioid release acutely after exercise in brain regions especially relevant for reward and cognitive processing. Fitness was not associated with MOR availability. We conclude that regular exercise training and higher aerobic fitness may induce neuroadaptation within the MOR system, which might contribute to improved emotional and behavioral responses associated with long-term exercise.

Obesity Blunts the Ventilatory Response to Exercise in Men and Women.

Rationale: Obesity presents a mechanical load to the thorax, which could perturb the generation of minute ventilation (V̇e) during exercise. Because the respiratory effects of obesity are not homogenous among all individuals with obesity and obesity-related effects could vary depending on the magnitude of obesity, we hypothesized that the exercise ventilatory response (slope of the V̇e and carbon dioxide elimination [V̇co2] relationship) would manifest itself differently as the magnitude of obesity increases.Objectives: To investigate the V̇e/V̇co2 slope in an obese population that spanned across a wide body mass index (BMI) range.Methods: A total of 533 patients who presented to a surgical weight loss center for pre-bariatric surgery testing performed an incremental maximal cycling test and were studied retrospectively. The V̇e/V̇co2 slope was calculated up to the ventilatory threshold. Patients were examined in groups based on BMI (category 1: 30-39.9 kg/m2, category 2: 40-49.9 kg/m2, and category 3: ≥50 kg/m2). Because the respiratory effects of obesity could be sex and/or age specific, we further examined patients in groups by sex and age (younger: <50 yr and older: ≥50 yr). Differences in the V̇e/V̇co2 slope were then compared between BMI category, age, and sex using a three-way ANOVA.Results: No significant BMI category by sex by age interactions was detected (P = 0.75). The V̇e/V̇co2 slope decreased with increases in BMI (category 1, 29.1 ± 4.0; category 2, 28.4 ± 4.1; and category 3, 27.1 ± 3.3) and was elevated in women (28.9 ± 4.1) compared with men (26.7 ± 3.2) (BMI category by sex interaction, P < 0.05). No age-related differences were observed (BMI category by age interaction, P = 0.55). The partial pressure for end-tidal CO2 was elevated at the ventilatory threshold in BMI category 3 compared with BMI categories 1 and 2 (both P < 0.01).Conclusions: These findings suggest that obesity presents a unique challenge to augmenting ventilatory output relative to CO2 elimination, such that the increase in the exercise ventilatory response becomes blunted as the magnitude of obesity increases. Further studies are required to investigate the clinical consequences and the mechanisms that may explain the attenuation of exercise ventilatory response with increasing BMI in men and women with obesity.

Heart rate variability kinetics during different intensity domains of cycling exercise in healthy subjects

ABSTRACT The purpose of this study was to verify the heart rate variability (HRV) and heart rate (HR) kinetics during the fundamental phase in different intensity domains of cycling exercise. Fourteen males performed five exercise sessions: (1) maximal incremental cycling test; (2) two rest-to-exercise transitions for each intensity domain, that is, heavy (Δ30) and severe (Δ60) domains. HRV markers (SD1 and SD2) and HR kinetics in the fundamental phase were analyzed by first-order exponential fitting. There were no significant differences in amplitude values between SD1Δ30 (8.98 ± 3.52 ms) and SD1Δ60 (9.44 ± 3.24 ms) and SD2Δ30 (24.93 ± 9.16 ms) and SD2Δ60 (25.98 ± 7.29 ms). Significant difference was observed between HRΔ30 (52 ± 7 bpm) and HRΔ60 (63 ± 8 bpm). The time constant (τ) values were significantly different between SD1Δ30 (17.61 ± 6.26 s) and SD1Δ60 (13.86 ± 5.90 s), but not between SD2Δ30 (20.06 ± 3.73 s) and SD2Δ60 (19.47 ± 6.03 s) or HRΔ30 (56.75 ± 18.22 s) and HRΔ60 (58.49 ± 15.61 s). However, the τ values for HRΔ30 were higher and significantly different in relation to SD1Δ30 and SD2Δ30, as well as for HRΔ60 in relation to SD1Δ60 and SD2Δ60. The kinetics of the autonomic variable (SD1 marker) was accelerated by the increased intensity. Moreover, significant differences were found for the τ values, with faster HRV markers than HR, in both intensities of Δ30 and Δ60, which suggests that these variables indicate distinct and specific cardiac autonomic response times during different intensity domains in cycling. HIGHLIGHTS The application of HRV to optimize exercise prescription at different effort intensities is extremely important to obtain assertive and effective results. Analysis of the kinetic responses of HRV is a useful tool for the evaluation of exercise performance and health status. A faster kinetics was found for HRV markers in comparison to HR, for both intensities analysed, which suggests that these variables indicate distinct and specific cardiac autonomic response times during different intensity domains in cycling.

Relationship Between Critical Power and Different Lactate Threshold Markers in Recreational Cyclists.

Purpose: To analyze the relationship between critical power (CP) and different lactate threshold (LT2) markers in cyclists.Methods: Seventeen male recreational cyclists [33 ± 5 years, peak power output (PO) = 4.5 ± 0.7 W/kg] were included in the study. The PO associated with four different fixed (onset of blood lactate accumulation) and individualized (Dmaxexp, Dmaxpol, and LTΔ1) LT2 markers was determined during a maximal incremental cycling test, and CP was calculated from three trials of 1-, 5-, and 20-min duration. The relationship and agreement between each LT2 marker and CP were then analyzed.Results: Strong correlations (r = 0.81–0.98 for all markers) and trivial-to-small non-significant differences (Hedges’ g = 0.01–0.17, bias = 1–9 W, and p > 0.05) were found between all LT2 markers and CP with the exception of Dmaxexp, which showed the strongest correlation but was slightly higher than the CP (Hedges’ g = 0.43, bias = 20 W, and p < 0.001). Wide limits of agreement (LoA) were, however, found for all LT2 markers compared with CP (from ±22 W for Dmaxexp to ±52 W for Dmaxpol), and unclear to most likely practically meaningful differences (PO differences between markers >1%, albeit <5%) were found between markers attending to magnitude-based inferences.Conclusion: LT2 markers show a strong association and overall trivial-to-small differences with CP. Nevertheless, given the wide LoA and the likelihood of potentially meaningful differences between these endurance-related markers, caution should be employed when using them interchangeably.

Acute Moderate Hypoxia Reduces One-Legged Cycling Performance Despite Compensatory Increase in Peak Cardiac Output: A Pilot Study.

In severe hypoxia, single-leg peak oxygen uptake (VO2peak) is reduced mainly due to the inability to increase cardiac output (CO). Whether moderate altitude allows CO to increase during single-leg cycling, thereby restoring VO2peak, has not been extensively investigated. Five healthy subjects performed an incremental, maximal, two-legged cycle ergometer test, and on separate days a maximal incremental one-leg cycling test in normoxia and in moderate hypoxia (fraction of inspired oxygen (FiO2) = 15%). Oxygen uptake, heart rate, blood pressure responses, power output, and CO (PhysioFlow) were measured during all tests. Moderate hypoxia lowered single-leg peak power output (154 ± 31 vs. 128 ± 26 watts, p = 0.03) and oxygen uptake (VO2) (36.8 ± 6.6 vs. 33.9 ± 6.9 mL/min/kg, p = 0.04), despite higher peak CO (16.83 ± 3.10 vs. 18.96 ± 3.59 L/min, p = 0.04) and systemic oxygen (O2) delivery (3.37 ± 0.84 vs. 3.47 ± 0.89 L/min, p = 0.04) in hypoxia compared to normoxia. Arterial–venous O2 difference (a–vDO2) was lower in hypoxia (137 ± 21 vs. 112 ± 19 mL/l, p = 0.03). The increases in peak CO from normoxia to hypoxia were negatively correlated with changes in mean arterial pressure (MABP) (p < 0.05). These preliminary data indicate that the rise in CO was not sufficient to prevent single-leg performance loss at moderate altitude and that enhanced baroreceptor activity might limit CO increases in acute hypoxia, likely by reducing sympathetic activation. Since the systemic O2 delivery was enhanced and the calculated a–vDO2 reduced in moderate hypoxia, a potential diffusion limitation cannot be excluded.

Effects of a vibrational proprioceptive stimulation on recovery phase after maximal incremental cycle test.

Global Proprioceptive Resonance (GPR) is a recently developed approach conceived to solicit the various cutaneous mechanoreceptors, through application of mechanical multifocal vibration at low amplitude and at definite body sites, limiting the stimulation of the profound structures. This interventional study evaluated the effects of GPR on cardiorespiratory function during the post-exertional recovery period. A group of volunteers involved in Triathlon (a multisport discipline consisting of sequential swim, cycle, and run disciplines higly demanding in terms of metabolic engagment), underwent two maximal incremental exercise tests until exhaustion followed alternatively to (a) a 13 minutes section of GPR or (b) a standard low intensity exercise acute trend of the same duration. These effects of these two approaches were compared in terms of recovery of: heart rate (HR), respiratory rate (RR), peripheral oxygen saturation (SpO2) and venous lactate concentration (Lac). The physiological parameters (HR, RR, SpO2 and Lac) recorded in the pre-exertion session showed similar values between the 40 volunteers while several differences were recorded in the post-exertion phase. After 6 min of GPR recovery it was recorded a drop in RR below baseline (19.4±4.15 min-1 vs. 12.2± 0.4 min-1; p<0.001) coupled with an increase in peripheral oxygen saturation above the baseline (GPR: 99.0%±0.16% vs. 96.6%±0.77%, p<0.001). Moreover, the most striking result was the drop in lactate concentration measured after 13 min of GPR recovery: 84.5±3.5% in GPR vs 2.9±7.6% reduction in standard recovery (p<0.001). Notably no differences were recorded recovery of heart rate. GPR has promising effects on post-exercise recovery on RR, SpO2 and lactate level on young athletes.

Salivary endocrine response following a maximal incremental cycling protocol with local vibration.

The aim of this study was to compare the effects of vibration (Vib versus noVib) during a maximal graded cycling exercise on hormonal response, precisely on cortisol (C) and testosterone (T). Twelve active males (25 ± 5yrs; 181 ± 5cm; 80.7 ± 11.1kg) randomly performed two maximal incremental cycling tests on two separate days and at the same time of the day (09:00). The protocol consisted of incremental steps of 3 min duration performed on a PowerBIKETM that induces vibration cycling. The study was a repeated measures design and participants performed the test with and without vibration. Gas exchange and heart rate (HR) were continuously assessed and blood lactate (Bla) was recorded at the end of each incremental stage. Saliva samples were collected before and immediately after the test, and analysed for (C) and (T).The results show that C and T increased in both cycling conditions; however, the C’s magnitude of change was significantly higher by 83% after Vib cycling in comparison to the no Vib (p = 0.014), whereas the T’s magnitude of change were not statistically different between trials (p = 0.715). Vibration induced a decrease of the T/C ratio (p = 0.046) but no significant changes were observed following noVib (p = 0.476). As a conclusion, the investigation suggests that adding mechanical vibration to cycling may potentiate a catabolic exercise-induced state, which could have potential clinical implications in rehabilitation and injury treatment. Sport experts should take this message home to carefully plan the recovery process and time during training and competitions.

A multidimensional assessment of dyspnoea in healthy adults during exercise.

(1) To determine whether healthy humans can distinguish between the intensity and unpleasantness of exertional dyspnoea; (2) to evaluate the reliability of qualitative dyspnoea descriptors during exercise; and (3) to assess the reliability of the Multidimensional Dyspnoea Profile (MDP) METHODS: Forty-four healthy participants (24M:20F, 25 ± 5years) completed maximal incremental cycling tests on three visits. During visit 1, participants rated the intensity and unpleasantness of dyspnoea simultaneously throughout exercise using the modified 0-10 category-ratio Borg scale. On visits 2 and 3, participants rated either the intensity or unpleasantness of dyspnoea alone at the same measurement times as visit 1. On all visits, participants selected qualitative descriptors throughout all exercise intensities from a list of 4, selected relevant qualitative descriptors from a list of 15 at peak exercise, and completed the MDP. Participants rated their dyspnoea intensity significantly higher for a given minute ventilation ([Formula: see text]) compared to dyspnoea unpleasantness (dyspnoea-[Formula: see text] slope: 0.08 ± 0.02 vs. 0.07 ± 0.03 Borg 0-10/Lmin-1, p < 0.001) during visit 1. The onset of intensity ratings occurred at a significantly lower work rate compared to unpleasantness ratings measured on the same exercise test (52 ± 41 vs. 91 ± 53 watts, p < 0.001). Dyspnoea intensity and unpleasantness remained significantly different for a given ventilation even when measured independently on separate exercise tests (p < 0.05). There was good-to-excellent reliability (ICC > 0.60) for the use of qualitative dyspnoea descriptors and the MDP to measure dyspnoea at peak exercise. Exercise-induced dyspnoea in healthy adults can differ in the sensory and affective dimensions, and can be measured reliably using qualitative descriptors and the MDP.

Impaired Cardiac Autonomic Control in Women With Fibromyalgia Is Independent of Their Physical Fitness.

Evidence has suggested abnormal cardiac autonomic responses to exercise in patients with fibromyalgia (FM). However, it is not clear whether the dysautonomia represents a reduced physical fitness rather directly related to FM pathogenesis. Thus, we aimed to verify the cardiac autonomic responses before, during, and after a maximal incremental exercise in women with FM and whether these hypothesized alterations would be dependent with their physical fitness. This is a cross-sectional study with 23 FM women and 17 healthy women. The participants performed a maximal incremental cycling test to determine their maximal workload (Wmax) and were further matched by their Wmax (14 FM patients, Wmax: 128.6 ± 16.2 W; and 14 healthy women, Wmax: 131.9 ± 15.9 W). Beat-to-beat heart rate (HR) was continuously monitored to calculate HR variability indexes at rest, chronotropic reserve during exercise, and HR recovery. Heart rate variability indexes related to vagal modulation were significantly lower in FM patients than in healthy women (p < 0.05). The chronotropic reserve and the HR recovery at 30, 120, 180, 300, and 600 seconds after exercise were all lower in FM patients compared with those of healthy women (p < 0.05). Similar findings were found when analysis was performed using the matched physical fitness subgroup. The documented cardiac autonomic abnormalities at rest, during, and after exercise in FM patients persist even when physical fitness status is taken in account. Thus, strategies to attenuate the dysautonomia in FM patients must be considered.