Relative Exercise Intensity Research Articles

The kinetics of cardiac troponin T release during and after 1- and 6-h maximal cycling trials

ObjectivesIn this study, the effects of short-duration high-intensity exercise and long-duration exercise on high-sensitivity cardiac troponin T (hs-cTnT) levels were compared. MethodsTwelve male amateur cyclists performed 1- and 6-h cycling trials. In both exercise trials, hs-cTnT was assessed at rest, immediately postexercise and at 1, 3, 6, 12, and 24 h postexercise. Additionally, hs-cTnT levels were assessed every hour during the 6-h trial. ResultsExercise resulted in an increase in hs-cTnT levels in all subjects. Circulating hs-cTnT levels increased in both exercise trials (p < 0.001), with higher peak values occurring after the 1-h trial compared with those of the 6-h trial (p = 0.023). The upper reference limit (URL) exceeded 83 % of the participants in the 1-h trial and 42 % of the participants in the 6-h trial. There was substantial individual variability in peak hs-cTnT in both trials. Values of hs-cTnT were greater after exercise than during exercise for the 6-h trial. For both exercise trials, the maximum postexercise hs-cTnT values correlated with the %HRMAX (r = 0.906 for the 1-h trial, r = 0.735 for the 6-h trial). For the 1-h trial, the maximum postexercise hs-cTnT values were observed at 3 h in all subjects. No significant difference in the hs-cTnT values was observed for the 6-h trial during the first 12 h postexercise. ConclusionsOur results demonstrated greater hs-cTnT levels in young male participants after a 1-h cycling trial than after a 6-h cycling trial, despite a substantially greater energy expenditure and total external work completed in the 6-h trial. Postexercise hs-cTnT values are associated with relative exercise intensity.

The delta concept does not effectively normalise exercise responses to exhaustive interval training

ObjectivesThis study was designed to quantify inter- and intra-individual variability in performance, physiological, and perceptual responses to high-intensity interval training prescribed using the percentage of delta (%Δ) method, in which the gas exchange threshold and maximal oxygen uptake (V̇O2max) are taken into account to normalise relative exercise intensity. DesignRepeated-measures, within-subjects design with mixed-effects modelling. MethodsEighteen male and four female cyclists (age: 36 ± 12 years, height: 178 ± 10 cm, body mass: 75.2 ± 13.7 kg, V̇O2max: 51.6 ± 5.3 ml·kg−1·min−1) undertook an incremental test to exhaustion to determine the gas exchange threshold and V̇O2max as prescription benchmarks. On separate occasions, participants then completed four high-intensity interval training sessions of identical intensity (70 %Δ) and format (4-min on, 2-min off); all performed to exhaustion. Acute high-intensity interval training responses were modelled with participant as a random effect to provide estimates of inter- and intra-individual variability. ResultsGreater variability was generally observed at the between- compared with the within-individual level, ranging from 50 % to 89 % and from 11 % to 50 % of the total variability, respectively. For the group mean time to exhaustion of 20.3 min, inter- and intra-individual standard deviations reached 9.3 min (coefficient of variation = 46 %) and 4.5 min (coefficient of variation = 22 %), respectively. ConclusionsDue to the high variability observed, the %Δ method does not effectively normalise the relative intensity of exhaustive high-intensity interval training across individuals. The generally larger inter- versus intra-individual variability suggests that day-to-day biological fluctuations and/or measurement errors cannot explain the identified shortcoming of the method.

Sex differences in fatiguability during single-joint resistance exercise in a resistance-trained population.

The primary aim of this study was to compare the fatiguability and acute recovery from a session of unilateral biceps curl exercise between habitually resistance-trained males and females. Twenty participants performed biceps curl one repetition maximum (1RM) and maximal voluntary contraction (MVC) testing of the elbow flexors. The exercise protocol consisted of four sets of unilateral biceps curls at 50% of the measured 1RM to volitional failure. MVC force and EMG activity of the elbow flexors were assessed following each set and during the recovery phase. The outcome variables compare the repetition volume, MVC strength loss, and EMG responses between males and females during the exercise and recovery phases. Across the exercise protocol, females completed significantly more repetitions compared to males (p < 0.01, d = 1.7) and lost significantly less strength across time (76% versus 69%, d = 0.48, p = 0.046). Additionally, females maintained a higher level of normalized EMG amplitude compared to males across the protocol (p = 0.035; d = 0.510). However, there were no sex differences in the strength (p = 0.562) or EMG (p = 0.607) responses during the recovery phase. In a resistance-trained population, females were able to perform a greater number of repetitions during the biceps curl exercise compared to their male counterparts at the same relative intensity of exercise. The ability of females to maintain a greater proportion of their maximal elbow flexor strength and muscle excitation during exercise suggests females can tolerate greater upper-body resistance exercise volume than males.

Differential effects of contracting muscle mass and relative exercise intensity on arterial plasma potassium concentration during and following incremental arm and leg cycling exercise

Whilst arm cycling is commonly used during clinical testing and rehabilitation, the associated changes in arterial plasma K+ concentration ([K+]a) and thus possible risks of associated hyperkalaemia and hypokalaemia are unknown. During exercise, K+ is released from contracting skeletal muscles and simultaneously taken up by inactive muscles, with [K+]a increasing markedly during intense exercise. Hence during exercise [K+]a should be influenced by both the contracting muscle mass and the relative exercise intensity. We therefore investigated the effects of incremental one-arm (1ARM) and two-leg (2LEGS) cycling on [K+]a, and on lactate ([Lac-]), hydrogen ([H+]), adrenaline and noradrenaline. Eight healthy participants performed 1ARM, rested (3.0 ± 0.2 h, mean±SE) then performed 2LEGS, with radial arterial blood sampled at rest, during common submaximal workrates (25, 50 W), peak workrate and 1–30 min post-exercise. During exercise at 50 W, VO2, [K+]a and [Lac-]a were higher during 1ARM than 2LEGS (P < 0.05). In contrast, at peak exercise, 2LEGS (272 ± 15 W) elicited higher VO2, [K+]a, [Lac-]a, [adrenaline]a and [noradrenaline]a than 1ARM (57 ± 4 W) (P < 0.05), with [H+]a elevated only in 2LEGS (P < 0.05). A curvilinear response for [K+]a versus %VO2peak was similar between modes, until diverging close to VO2peak. The slope of the log[K+]a versus %VO2peak regression was higher in 2LEGS (P < 0.01), indicating greater [K+]a throughout exercise utilising a larger muscle mass, and similarly for [Lac-]a. In conclusion, during exercise utilising a smaller contracting muscle mass, [K+]a and [Lac-]a were greater at the same absolute submaximal work rate compared to utilising a large muscle mass. Whilst responses were similar between modes when expressed against relative exercise intensity, [K+]a and [Lac-]a were higher during exercise with a large muscle mass. Hence, for submaximal exercise, the relative intensity is more important in determining [K+]a and [Lac-]a, but the size of the contracting muscle mass still exerts a positive effect, whilst during peak exercise, the size of the active muscle mass was more important in determining [K+]a and [Lac-]a. Furthermore, arm cycling did not induce marked disturbances in [K+]a during or after exercise, suggesting minimal associated myocardial risks and thus supporting its safe use in clinical and aged populations.

P047 Deconditioning in quiescent Crohn’s Disease patients with heightened fatigue perception

Abstract Background Heightened fatigue perception and premature exercise fatigue are common in inflammatory bowel disease (IBD). Physical deconditioning is greater in patients with increased fatigue perception relative to patients with a lower perception of fatigue, implicating deconditioning as an aetiological factor. This study used physiology and multiparametric Magnetic Resonance Imaging and Spectroscopy (MRI/MRS) during exercise to comprehensively phenotype quiescent IBD fatigue. Methods Participant body mass and regional body composition was assessed by DEXA, and tknee extensor strength and fatiguability using isokinetic dynamometry (Cybex, USA). A supine CPET was performed using an MR-compatible Ergometer (Cardiostepper, Ergospect) to standardize relative exercise intensity for in-bore 1H MRI measures. 1H MRI data were collected on a Philips 3T Ingenia wide bore scanner using a Philips Head/Neck coil and in-built posterior coil. Across rest, steady-state exercise (50% VO2 peak) and recovery, Phase Contrast-MRI was used to compute cardiac output and cerebral blood flow (CBF), and T2 Relaxation under spin tagging (TRUST-MRI) to measure brain oxygen extraction fraction (OEF). 31P MRS data was collected on a 3T Philips Achieva using a 14cm 31P coil over the medial gastrocnemius. Ischaemic plantar flexion exercise was performed at 50% maximum voluntary contraction (MVC) using an MR-compatible ergometer (Trispect, Ergospect) during non-localized pulse-acquire 31P-MRS. 31P spectra were analysed using the AMARES function in jMRUI Beta 6.0. In vivo muscle mitochondrial flux during post-exercise PCr recovery (VPCr = kPCr * ΔPCr) where ΔPCr is PCrendrecovery –PCrendex) was quantified after reinstating limb blood flow and fitting PCr recovery to a mono-exponential function in GraphPad prism (PCr(t) = PCrinitial+(PCrend – PCrinitial)(1-exp(-k.t) where t is time from start of non-ischaemic recovery). Results 16 quiescent CD patients and 12 age and BMI matched HV’s completed the study. General fatigue score was greater in CD relative to HV (P = 0.001, Table 1). Body composition, isometric strength, fatigue development were not different between groups (Table 1). CBF response to steady-state exercise was less in CD (P = 0.003) alongside the maintenance of cardiac output and brain OEF in HV (Figure 1). VPCr following ischemic plantar flexion exercise was less in CD than HV (P = 0.02, Figure 1) (Figure 1). Conclusion Greater fatigue perception in CD was accompanied by lower CBF on exercise and blunted post-exercise PCr resynthesis, but no differences in body composition, strength and fatiguability relative to HV. These finding point to greater deconditioning in CD, corroborated by their lower daily step count relative to HV.

Competitive Cross-Country Skiers Have Longer Time to Exhaustion Than Recreational Cross-Country Skiers During Intermittent Work Intervals Normalized to Their Maximal Aerobic Power.

To investigate differences in time to exhaustion (TTE), O2 uptake (V˙O2), and accumulated O2 deficit (O2def) between competitive and recreational cross-country (XC) skiers during an intermittent-interval protocol standardized for maximal aerobic power (MAP). Twelve competitive (maximal V˙O2 [V˙O2max]=76.5±3.8 mL·kg-1·min-1) and 10 recreational (V˙O2max=63.5±6.3 mL·kg-1·min-1) male XC skiers participated. All tests were performed on a rollerski treadmill in the V2 ski-skating technique. To quantify MAP and maximal accumulated oxygen deficit(MAOD), the skiers performed a steady-state submaximal test followed by a 1000-m time trial. After a 60-minute break, TTE, V˙O2, and accumulated O2def were measured during an intermittent-interval protocol (40-s work and 20-s recovery), which was individually tailored to 120% and 60% of each subject's MAP. During the 1000-m time trial, the competitive skiers had 21% (95% CI, 12%-30%) shorter finish time and 24% (95% CI, 14%-34%) higher MAP (all P < .01) than the recreational skiers. No difference was observed in relative exercise intensity (average power/MAP; P = .28), MAOD (P = .18), or fractional utilization of V˙O2max. During the intermittent-interval protocol, the competitive skiers had 34% (95% CI, 3%-65%) longer TTE (P = .03) and accumulated 61% (95% CI, 27%-95%) more O2def (P = .001) than the recreational skiers during work phases. Competitive XC skiers have longer TTE and accumulate more O2def than recreational XC skiers during an intermittent-interval protocol at similar intensity relative to MAP. This implies that performance in intermittent endurance sports is related to the ability to repeatedly recharge fractions of MAOD.

Exercise intensity domains determined by heart rate at the ventilatory thresholds in patients with cardiovascular disease: new insights and comparisons to cardiovascular rehabilitation prescription recommendations

ObjectivesTo compare the elicited exercise responses at ventilatory thresholds (VTs: VT1 and VT2) identified by cardiopulmonary exercise testing (CPET) in patients with cardiovascular disease (CVD) with the guideline-directed exercise intensity...

Effects of a Home-Based Physical Activity Program on Blood Biomarkers and Health-Related Quality of Life Indices in Saudi Arabian Type 2 Diabetes Mellitus Patients: A Randomized Controlled Trial.

The purpose of this study was to undertake a randomized control trial examining the effects of a 12-week home-based physical activity program on Saudi Arabian adults with type 2 diabetes. Sixty-four patients with type 2 diabetes mellitus were recruited from the Jazan Diabetes and Endocrinology Center, located in the Jazan region of southwestern Saudi Arabia. Patients were randomly assigned to either control, i.e., usual care (males = 46.9% and females = 53.1%, age = 45.88 ± 8.51 years, mass = 76.30 ± 15.16 kg, stature = 160.59 ± 8.94 cm, body mass index (BMI) = 29.73 ± 6.24 kg/m2, years since diagnosis = 8.12 ± 6.22 years) or a home-based physical activity (males = 50% and females = 50%, age = 42.07 ± 9.72 years, mass = 74.58 ± 13.67 kg, stature = 158.94 ± 9.38 cm, BMI = 29.44 ± 4.38 kg/m2, years since diagnosis = 12.17 ± 8.38 years) trial arms. The home-based physical activity group was required to undertake aerobic training by increasing their habitual step count by 2000 steps per day and performing resistance training 3 times per week for 12 weeks. The primary outcome was hemoglobin A1c (HbA1c), and secondary measures of anthropometrics, blood biomarkers, physical fitness, and patient-reported quality of life outcomes pertinent to type 2 diabetes were measured at timepoints, i.e., baseline, 12 weeks, and 24 weeks (follow-up). Intention-to-treat analyses revealed no significant alterations in the primary outcome (control: baseline = 8.71%, 12-weeks = 8.35%, and follow-up = 8.72%; home-based physical activity: baseline = 8.32%, 12-weeks = 8.06%, and follow-up = 8.39%) between trial arms. However, improvements in psychological wellbeing at follow-up measured using the Patient Health Questionnaire-9 were significantly greater in the home-based physical activity group (baseline = 6.84, 12-weeks = 5.96, and follow-up = 5.00) compared to the control (baseline = 6.81, 12-weeks = 5.73, and follow-up = 8.53). No other statistically significant observations were observed. Home-based physical activity is not effective in mediating improvements in HbA1c levels or secondary hematological, blood pressure, anthropometric, or fitness indices. However, given the link between psychological wellbeing and the etiology/progression of disease activity in type 2 diabetes, home-based physical activity may be effective for tertiary disease management. Future trials should examine the efficacy of relative exercise intensities greater than those in the current study.

Fitness and metabolic response to exercise in young adult survivors of childhood lymphoma.

Childhood lymphoma survivors (CLSs) are at high risk of reduced daily activity. This work studied metabolic substrate use and cardiorespiratory function in response to exercise in CLSs. Twenty CLSs and 20 healthy adult controls matched for sex, age, and BMI took an incremental submaximal exercise test to determine fat/carbohydrate oxidation rates. Resting echocardiography and pulmonary functional tests were performed. Physical activity level, and blood metabolic and hormonal levels were measured. CLSs reported more physical activity than controls (6317 ± 3815 vs. 4268 ± 4354 MET-minutes/week, p = 0.013), had higher resting heart rate (83 ± 14 vs. 71 ± 13bpm, p = 0.006), and showed altered global longitudinal strain (- 17.5 ± 2.1 vs. - 19.8 ± 1.6%, p = 0.003). We observed no difference in maximal fat oxidation between the groups, but it was reached at lower relative exercise intensities in CLSs (Fatmax 17.4 ± 6.0 vs. 20.1 ± 4.1mL/kg, p = 0.021). At V̇O2 peak, CLSs developed lower relative exercise power (3.2 ± 0.9 vs. 4.0 ± 0.7 W/kg, p = 0.012). CLSs reported higher levels of physical activity but they attained maximal fat oxidation at lower relative oxygen uptake and applied lower relative power at V̇O2peak. CLSs may thus have lower muscular efficiency, causing greater fatigability in response to exercise, possibly related to chemotherapy exposure during adolescence and childhood. Long-term follow-up is essential and regular physical activity needs to be sustained.

Blood Pressure Responses to Postexercise Circulatory Occlusion Are Attenuated After Exercise-Induced Muscle Weakness.

Exercise blood pressure (BP) responses are thought to be determined by relative exercise intensity (percent maximal voluntary contraction (MVC) strength). However, cross-sectional studies report that during a static contraction, higher absolute force is associated with greater BP responses to relative intensity exercise and subsequent muscle metaboreflex activation with postexercise circulatory occlusion (PECO). We hypothesized that a bout of unaccustomed eccentric exercise would reduce knee extensor MVC and subsequently attenuate BP responses to PECO. Continuous BP, heart rate, muscle oxygenation, and knee extensor electromyography were recorded in 21 young healthy individuals (female, n = 10) during 2 min of 20% MVC static knee extension exercise and 2 min of PECO, performed before and 24 h after 300 maximal knee extensor eccentric contractions to cause exercise-induced muscle weakness. As a control, 14 participants repeated the eccentric exercise 4 wks later to test whether BP responses were altered when exercise-induced muscle weakness was attenuated via the protective effects of the repeated bout effect. Eccentric exercise reduced MVC in all participants (144 ± 43 vs 110 ± 34 N·m, P < 0.0001). BP responses to matched relative intensity static exercise (lower absolute force) were unchanged after eccentric exercise ( P > 0.99) but were attenuated during PECO (systolic BP: 18 ± 10 vs 12 ± 9 mm Hg, P = 0.02). Exercise-induced muscle weakness modulated the deoxygenated hemoglobin response to static exercise (64% ± 22% vs 46% ± 22%, P = 0.04). When repeated after 4 wks, exercise-induced weakness after eccentric exercise was attenuated (-21.6% ± 14.3% vs -9.3 ± 9.7, P = 0.0002) and BP responses to PECO were not different from control values (all, P > 0.96). BP responses to muscle metaboreflex activation, but not exercise, are attenuated by exercise-induced muscle weakness, indicating a contribution of absolute exercise intensity on muscle metaboreflex activation.

Effects of hypoxia on exercise-induced diaphragm fatigue in healthy males and females.

Following high-intensity, normoxic exercise there is evidence to show that healthy females, on average, exhibit less fatigue of the diaphragm relative to males. In the present study, we combined hypoxia with exercise to test the hypothesis that males and females would develop a similar degree of diaphragm fatigue following cycle exercise at the same relative exercise intensity. Healthy young participants (n=10 male; n=10 female) with a high aerobic capacity (120% predicted) performed two time-to-exhaustion (TTE; ~85% maximum) cycle tests on separate days breathing either a normoxic or hypoxic (FiO2 =0.15) gas mixture. Fatigue of the diaphragm was assessed in response to cervical magnetic stimulation prior to, immediately post-exercise, 10-, 30-, and 60-min post-exercise. Males and females had similar TTE durations in normoxia (males: 690 ± 181 s; females: 852 ± 401 s) and hypoxia (males: 381 ± 160 s; females: 400 ± 176 s) (p > 0.05). Cycling time was significantly shorter in hypoxia versus normoxia in both males and females (p < 0.05) and did not differ on the basis of sex (p > 0.05). Following the hypoxic TTE tests, males and females experienced a similar degree of diaphragm fatigue compared to normoxia as shown by 20%-25% reductions in transdiaphragmatic twitch pressure. This occurred despite the fact that exercise time in hypoxia was substantially shorter relative to normoxia and the cumulative diaphragm work was lower. We also observed that females did not fully recover from diaphragm fatigue in hypoxia, whereas males did (p < 0.05). Sex differences in the rate of diaphragm contractility recovery following exercise in hypoxia might relate to sex-based differences in substrate utilization or diaphragm blood flow.

BENEFÍCIOS DA CORRIDA PARA A PROTEÇÃO CARDÍACA E A CULTURA DA CONSCIÊNCIA SANITÁRIA DO EXERCÍCIO

ABSTRACT Introduction: Several programs to encourage physical activity has been encouraged to reduce the sedentary lifestyle in China. Running is among them because it has potentially positive effects on cardiovascular diseases, hypertension, diabetes mellitus, and hypercholesterolemia, in addition to the intrinsic psychological and social benefits of outdoor sports. Objective: Explore the protective effect of running on the cardiac system by analyzing strategies for cultivating exercise health awareness. Methods: A group of ten healthy volunteers, five women aged 25-35 years, underwent a 45-minute running program, performed four times a week for three weeks. Data collected by spirometry and cardiac monitoring were collected, treated, compared, and discussed. This paper introduced the concept of subjective exercise intensity to find the best analysis and judgment of Cardiac Function. Finally, a quantitative investigation involving the analysis of 315 questionnaires explored the current status of sports health awareness in running fans. Results: Heart rate amplitude during running remained in the range of 120-160, belonging to the normal heart rate range for the surveyed audience. In most cases, women's heart rate was higher than men's (P&lt;0.05). The exercise intensity was fixed at a frequency below the value of 16, which is a slightly strenuous stage, and the relative exercise intensity was controlled between 50% and 71.5%. Conclusion: Running has a good cardiac protective effect, and its followers are highly aware of sports health. Due to the beneficial effect of sports practice, its dissemination is recommended as a form of physical and social therapeutic activity. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Changes in submaximal and maximal measures of cardio-respiratory fitness resulting from 6-days of mountain walking

ABSTRACT Trekking is a popular activity associated with cardiovascular benefits. The aim of the present study was to investigate changes in the submaximal heart rate, oxygen uptake, oxygen pulse, and blood lactate concentration associated with a 6-day mountain walk. Over a 12-year period, 134 male (age 21.0 ± 1.4 years) and 124 female undergraduates (age 20.8 ± 1.6 years) participated. Three days before the trek submaximal and maximal laboratory measures were made on participants walking on a motorized treadmill using a breath-by-breath system to measure oxygen uptake (VO2) during exercise. Oxygen uptake and heart rate were recorded during steady-state exercise at treadmill gradients 0, 4, 8, 12, and 16%. Measurements were made, at the same time of day, two days after the trek. There were significant improvements in both the walking economy and the relative exercise intensity (%VO2max) at submaximal treadmill gradients 0-16%. Post-trek, heart rate was lower while oxygen pulse was higher, at each treadmill gradient. There was a significant increase in the maximal oxygen uptake for men (+2.7%) and women (+2.9%). The results of the present study suggest that improvements in cardiorespiratory fitness are associated with a 6-day mountain walk with no sex difference in the exercise response. .

Power Profile Index: An Adjustable Metric for Load Monitoring in Road Cycling

Workload is calculated from exercise volume and intensity. In endurance sports, intensity has been measured using heart rate or RPE, giving rise to load indexes such as sRPE or TRIMP. In cycling, the advent of power meters led to new indexes, such as TSS. All these indexes have limitations, especially for high intensity exercise. Therefore, a new index for cycling is proposed, the Power Profile Index (PPi), which includes a weighting factor obtained from the relative exercise intensity and stage type. Using power data from 67 WorldTour cyclists and fatigue records in different stage types from 102 road cyclists, weighting factors for intensity and stage type were determined. Subsequently, the PPi was computed and compared to current indexes using data from a WorldTour team during the 2018 Tour de France. The proposed index showed a strong correlation with perceived fatigue as a function of stage type (R2 = 0.9996), as well as no differences in the load quantification in different types of stage profiles (p = 0.292), something that does not occur with other indexes such as TSS, RPE, or eTRIMP (p &lt; 0.001). Therefore, PPi is a new index capable of quantifying the high intensity efforts that produce greater fatigue, as well as considering the stage type.

Maximizing anaerobic performance with repeated-sprint training in hypoxia: In search of an optimal altitude based on pulse oxygen saturation monitoring.

Purpose: Repeated-sprint training in hypoxia (RSH) leads to great improvements in anaerobic performance. However, there is no consensus about the optimal level of hypoxia that should be used during training to maximize subsequent performances. This study aimed to establish whether such an optimal altitude can be determined and whether pulse oxygen saturation during RSH is correlated with training-induced improvement in performance. Methods: Peak and mean power outputs of healthy young males [age (mean ± SD) 21.7 ± 1.4 years] were measured during a Wingate (30 s) and a repeated-sprint ability (RSA; 10 x 6-s sprint with 24-s recovery) test before and after RSH. Participants performed six cycling sessions comprising three sets of 8 x 6-s sprint with 24-s recovery in normobaric hypoxia at a simulated altitude of either 1,500 m, 2,100 m, or 3,200 m (n = 7 per group). Heart rate variability was assessed at rest and during recovery from Wingate test before and after RSH. Results: The subjective rating of perceived exertion and the relative exercise intensity during training sessions did not differ between the three groups, contrary to pulse oxygen saturation (p < 0.001 between each group). Mean and peak power outputs were significantly increased in all groups after training, except for the mean power in the RSA test for the 3200 m group. Change in mean power on RSA test (+8.1 ± 6.6%) was the only performance parameter significantly correlated with pulse oxygen saturation during hypoxic training (p < 0.05, r = 0.44). The increase in LnRMSSD during recovery from the Wingate test was enhanced after training in the 1,500 m (+22%) but not in the two other groups (≈– 6%). Moreover, the increase in resting heart rate with standing after training was negatively correlated with SpO2 (p < 0.01, r =–0.63) suggesting that hypoxemia level during training differentially altered autonomic nervous system activity. Conclusion: These data indicate that RSH performed as early as 1,500 m of altitude is effective in improving anaerobic performance in moderately trained subjects without strong association with pulse oxygen saturation monitoring during training.

Changes in training activity post COVID-19 infection in recreational runners and cyclists.

Anecdotal evidence suggests that athletes struggle to return to exercise post COVID-19 infection. However, studies evaluating the effect of COVID-19 on athletes' exercise activity are limited. The objectives of this study were: (i) to describe the perceptions of recreational runners and cyclists recovering from COVID-19 on their training activity and general well-being, (ii) to compare device-measured training data in runners and cyclists pre- and post COVID-19, with non-infected controls that had a training interruption. Participants who were recruited via social media completed an online questionnaire (n=61), including demographic, health and COVID-19 descriptive data. In a sub-sample, device-measured training data (heart rate, time, distance and speed, n=27) were obtained from GPS devices for four weeks before infection and on resumption of training. Similar data were collected for the control group (n=9) whose training had been interrupted but by factors excluding COVID-19. Most participants experienced a mild to moderate illness (91%) that was associated with a training interruption time of two-four weeks. Decreases in heart rate, relative exercise intensity, speed, time and distance were observed during the first week of returning to training for both groups, followed by an increase from Week two onwards. Results failed to support a 'COVID-19 effect' on exercise activity as reductions in training variables occurred in both the COVID-19 and control groups. A possible explanation for the reductions observed is a deliberate gradual return to training by athletes post-COVID-19. More research is needed using device-measured training data prior to and post COVID-19 infection to better understand the impact of the SARS-CoV-2 virus on the exercise activity of athletes.

Brain-muscle interplay during endurance self-paced exercise in normobaric and hypobaric hypoxia.

Purpose: Hypoxia is one major environmental factor, supposed to mediate central motor command as well as afferent feedbacks at rest and during exercise. By using a comparison of normobaric (NH) and hypobaric (HH) hypoxia with the same ambient pressure in oxygen, we examined the potential differences on the cerebrovascular and muscular regulation interplay during a self-paced aerobic exercise. Methods: Sixteen healthy subjects performed three cycling time-trials (250 kJ) in three conditions: HH, NH and normobaric normoxia (NN) after 24 h of exposure. Cerebral and muscular oxygenation were assessed by near-infrared spectroscopy, cerebral blood flow by Doppler ultrasound system. Gas exchanges, peripheral oxygen saturation, power output and associated pacing strategies were also continuously assessed. Results: The cerebral oxygen delivery was lower in hypoxia than in NN but decreased similarly in both hypoxic conditions. Overall performance and pacing were significantly more down-regulated in HH versus NH, in conjunction with more impaired systemic (e.g. saturation and cerebral blood flow) and prefrontal cortex oxygenation during exercise. Conclusions: The difference in pacing was likely the consequence of a complex interplay between systemic alterations and cerebral oxygenation observed in HH compared to NH, aiming to maintain an equivalent cerebral oxygen delivery despite higher adaptive cost (lower absolute power output for the same relative exercise intensity) in HH compared to NH.

Training and match demands differ between the regular season and finals in semi-professional basketball.

Basketball competitions often include a scheduled regular season followed by knock-out finals. Understanding training and match demands through the season can help optimize performance and reduce injury risk. This study investigated whether training and/or match demands differed between the regular season and finals, and whether these differences were dependent on player role. Average session intensity and volume and durations of relative exercise intensities (inactive, light, moderate-vigorous, maximal, supramaximal) were quantified during training sessions and matches using accelerometry in two semi-professional basketball teams (n = 23; 10 women, 13 men). Training and match demands were compared between the regular season (training: 445 observations; matches: 387 observations) and finals (training: 113 observations, matches: 75 observations) with consideration of player role (starters, in-rotation bench, out-rotation bench). During finals matches, starters received 4.4 min more playing time (p = 0.03), performed 14% more absolute maximal activity (p < 0.01) and had 8% less relative inactive time (p = 0.02) when compared to the regular season. Out-rotation bench players received 2.1 min less playing time (p < 0.01), performed 33% less absolute maximal activity (p = 0.01) and 57% less absolute supramaximal activity (p < 0.01) in finals when compared to the regular season. During finals training sessions, average training intensity was 5% higher (p = 0.02), absolute moderate-vigorous activity was 3% higher (p = 0.04), relative maximal activity was 12% higher (p < 0.01), and relative inactive time was 5% lower (p = 0.03) when compared to the regular season. These findings suggest starters need to be physically prepared for greater match demands during finals, while out-rotation bench players should supplement their training during finals with extra supramaximal activity to maintain their conditioning levels for matches.

Exercise intensity and energy expenditure of a multicomponent home-based training program: Xiangya hospital circuit training (X-CircuiT).

IntroductionOur previous studies showed that Xiangya Hospital Circuit Training (X-CircuiT) effectively improved physical fitness and reversed pre-frailty in community-dwelling older adults. This study aimed to explore the generalizability and applicability of X-CircuiT in different aged populations in the context of exercise intensity and energy expenditure.MethodsWe prospectively recruited 72 community-dwelling sedentary adults, twelve adults divided into 6 age groups ranging from 20 to 80 years old and separated by decades. Cardiopulmonary exercise testing was performed to determine peak heart rate (HRpeak). An individual HR-oxygen consumption regression equation was fit for each participant, and then a session of remote heart rate monitored X-CircuiT was performed. Exercise intensity (%HRpeak) and energy expenditure of X-CircuiT among the six age groups were assessed. Further sub-analysis was conducted by dividing the participants by peak metabolic equivalent (MET) values, <5 METs, 5–7 METs, and more than 7METs to explore the relationship between maximum exercise capacity and exercise intensity of X-CircuiT.ResultsThe average %HRpeak of X-CircuiT for subjects in the 20–29, 30–39, 40–49, 50–59, 60–69, and 70–80 age groups were 54 ± 6, 59 ± 8, 60 ± 8, 62 ± 5, 66 ± 10, and 67 ± 13, respectively (p = 0.008); and the average energy expenditure was 121.9 ± 26.5, 123.3 ± 33.8, 129.2 ± 40.9, 130.9 ± 31.8, 146.8 ± 29.0, and 125.0 ± 28.4 kcal, respectively. The average %HRpeak for the warm-up, aerobic, acupoint patting, resistance, and stretching stages in overall subjects was 61 ± 9, 70 ± 10, 70 ± 10, 63 ± 9, and 57 ± 9, respectively. Furthermore, when subjects were divided by peak METs, it was found that the lower the peak METs, the greater the value of the relative exercise intensity indicators. The aerobic and acupoint stages of X-CircuiT could illicit a response of high intensity for those with peak METs <5, moderate intensity in those with peak METs of 5–7, and low-intensity for those with peak METs of more than 7.ConclusionXiangya Hospital Circuit Training followed the principle of low-intensity warm-up and medium-intensity training with multicomponent exercise training. It is classified as a moderate-intensity exercise for sedentary middle-aged and older adults, or those with a maximum exercise capacity of 5–7 METs, and is classified as a low-intensity exercise for young people.

Energy Consumption of Water Running and Cycling at Four Exercise Intensities.

Water exercise provides a workload in every direction of motion for training in a reduced impact environment. The selection of an appropriate physical activity and an individual exercise prescription are essential to obtain training effects. The aim of the present study was to determine individualised relative exercise intensities at four speeds of motion for water cycling and water running. Running was tested both in buoyancy and with the feet in contact with the bottom of the pool. To this purpose, gas exchanges, heart rate, and blood lactate were measured in each test session. Fourteen active, healthy females (23.2 ± 1.6 years) underwent a dry land maximal incremental protocol to exhaustion on a treadmill and hydrobike (HB); they engaged in water running with ground contact (RC) and water running suspended (RS) tests in a swimming pool at 30, 40, 50, and 60 cycles per minute (cpm), submerged at the individual xiphoid level. The four motion speeds of the three water exercise modalities ranged from 50% to 95% of the maximal heart rate and the maximal oxygen uptake, representing a moderate-to-vigorous training stimulus. RS elicited the lowest oxygen consumption, whereas HB demanded the significantly highest oxygen consumption and presented the highest blood lactate accumulation, with vigorous intensity being reached at 50 cpm and near maximal intensity at 60 cpm. It appears that water cycling could be more suitable for athletic training, whereas water running could be more appropriate for health and fitness purposes.