Incremental Cycle Research Articles

The Effects of Beverage Intake after Exhaustive Exercise on Organ Damage, Inflammation and Oxidative Stress in Healthy Males.

Strenuous exercise induces organ damage, inflammation and oxidative stress. To prevent exercise-induced organ damage, inflammation and oxidative stress, rehydrating may be an effective strategy. In the present study, we aimed to examine whether beverage intake after exhaustive exercise to recover from dehydration prevents such disorders. Thirteen male volunteers performed incremental cycling exercise until exhaustion. Immediately after exercise, the subjects drank an electrolyte containing water (rehydrate trial: REH) or did not drink any beverage (control trial: CON). Blood samples were collected before (Pre), immediately (Post), 1 h and 2 h after exercise. Urine samples were also collected before (Pre) and 2 h after exercise. We measured biomarkers of organ damage, inflammation and oxidative stress in blood and urine. Biomarkers of muscle, renal and intestinal damage and inflammation increased in the blood and urine after exercise. However, changes in biomarkers of organ damage and inflammation did not differ between trials (p > 0.05). The biomarker of oxidative stress, thiobarbituric acid reactive substances (TBARS), in plasma, showed different changes between trials (p = 0.027). One hour after exercise, plasma TBARS concentration in REH had a higher trend than that in CON (p = 0.052), but there were no significant differences between Pre and the other time points in each trial. These results suggest that beverage intake after exercise does not attenuate exercise-induced organ damage, inflammation or oxidative stress in healthy males. However, rehydration restores exercise-induced oxidative stress more quickly.

Novel Real-Time OEP Phase Angle Feedback System for Dysfunctional Breathing Pattern Training-An Acute Intervention Study.

Dysfunctional breathing patterns (DBP) can have an impact on an individual’s quality of life and/or exercise performance. Breathing retraining is considered to be the first line of treatment to correct breathing pattern, for example, reducing ribcage versus abdominal movement asynchrony. Optoelectronic plethysmography (OEP) is a non-invasive 3D motion capture technique that measures the movement of the chest wall. The purpose of this study was to investigate if the use of a newly developed real-time OEP phase angle and volume feedback system, as an acute breathing retraining intervention, could result in a greater reduction of phase angle values (i.e., an improvement in movement synchrony) when compared to real-time OEP volume feedback alone. Eighteen individuals with a DBP performed an incremental cycle test with OEP measuring chest wall movement. Participants were randomly assigned to either the control group, which included the volume-based OEP feedback or to the experimental group, which included both the volume-based and phase angle OEP feedback. Participants then repeated the same cycle test using the real-time OEP feedback. The phase angle between the ribcage versus abdomen (RcAbPhase), between the pulmonary ribcage and the combined abdominal ribcage and abdomen (RCpAbPhase), and between the abdomen and the shoulders (AbSPhase) were calculated during both cycle tests. Significant increases in RcAbPhase (pre: −2.89°, post: −1.39°, p < 0.01), RCpAbPhase (pre: −2.00°, post: −0.50°, p < 0.01), and AbSPhase (pre: −2.60°, post: −0.72°, p < 0.01) were found post-intervention in the experimental group. This indicates that the experimental group demonstrated improved synchrony in their breathing pattern and therefore, reverting towards a healthy breathing pattern. This study shows for the first time that dysfunctional breathing patterns can be acutely improved with real-time OEP phase angle feedback and provides interesting insight into the feasibility of using this novel feedback system for breathing pattern retraining in individuals with DBP.

Mechanisms of Exertional Dyspnea in Patients with Mild COPD and a Low Resting DLCO

Patients with mild chronic obstructive pulmonary disease (COPD) and lower resting diffusing capacity for carbon monoxide (DLCO) often report troublesome dyspnea during exercise although the mechanisms are not clear. We postulated that in such individuals, exertional dyspnea is linked to relatively high inspiratory neural drive (IND) due, in part, to the effects of reduced ventilatory efficiency. This cross-sectional study included 28 patients with GOLD I COPD stratified into two groups with (n = 15) and without (n = 13) DLCO less than the lower limit of normal (<LLN; Global Lung Function Initiative criteria) and 16 healthy controls. We compared dyspnea (Borg scale), IND (by diaphragm electromyography), ventilatory equivalent for CO2 (V̇ E/V̇CO2), and respiratory mechanics during incremental cycle exercise in the three groups. Spirometry and resting lung volumes were similar between COPD groups. During exercise, dyspnea, IND and V̇ E/V̇CO2 were higher at equivalent work rates (WR) in the DLCO<LLN group compared with the other two groups (all p < 0.05). In patients with DLCO<LLN, severe respiratory mechanical constraints, indicated by end-inspiratory lung volume of approximately 90% of total lung capacity, occurred at a lower WR than the other two groups (p < 0.05). The dyspnea/IND relationship was similar across groups; therefore, the increased dyspnea at a standardized WR in the low DLCO<LLN group reflected the higher corresponding IND. Higher dyspnea ratings in patients with mild COPD and DLCO<LLN were associated with higher IND and V̇ E/V̇CO2 at a given work rate. Higher ventilatory requirements in the DLCO<LLN group accelerated dynamic mechanical abnormalities earlier in exercise, further increasing IND and dyspnea.

Sex differences in post‐inspiratory inspiratory activity and evolution of net respiratory muscle pressures during incremental exercise

The respiratory muscle pressure (Pmus) waveform allows observation of net inspiratory andexpiratory muscle recruitment under a wide variety of conditions, including mechanical ventilation, spontaneous breathing, and during exercise. Observation of the Pmus waveform during incremental and constant work rate cycling reveals that inspiratory and expiratory muscle recruitment systematically increase with rising minute ventilations. Additionally, measuring Pmus allows one to assess the post-inspiratory inspiratory muscle activity (PIIA), whereby the inspiratory muscles “brake” some or all of expiration to allow for a smoother transition in muscle recruitment. In recent years, it has become increasingly evident that the work of breathing is systematically higher for women compared with men at a given minute ventilation during exercise. It is possible that a greater evolution of net respiratory pressures, as well as longer PIIA duration, may be a contributing factor to the greater work of breathing observed in women during exercise. However, to date, no study has examined the potential sex differences in Pmus, nor PIIA, during exercise. Thus, a comprehensive assessment of the Pmus and PIIA during exercise between sexes is warranted. PURPOSE To compare PIIA and inspiratory and expiratory Pmus between men and women during incremental cycling. METHODS Fifteen women (21 ± 2 yrs; 167 ± 7 cm; 62 ± 7 kg) and 19 men (24 ± 4 yrs; 182 ± 5 cm; 81 ± 10 kg) visited the laboratory on two separate occasions. The first occasion was used to obtain informed consent and to screen participants for normal pulmonary function (>85% age-predicted). On the second visit, participants were instrumented with an esophageal balloon catheter to estimate variations in pleural pressure (Ppl). Quasi-static relaxation curves were obtained to measure chest wall recoil pressure (Pcw). Participants then completed an incremental cycling protocol until volitional exhaustion. Pmus was calculated at given minute ventilations during the exercise protocol as follows: Pmus = Pcw – Ppl. RESULTS Total Pmus (sum of average inspiratory and expiratory Pmus) was greater in women than men (P < 0.05). Peak inspiratory Pmus was similar between sexes, but peak expiratory Pmus was greater in women. The average rates of change (slope) in Pmus during inspiration and expiration were significantly faster in women than men at a given minute ventilation (P < 0.05). Finally, the duration of PIIA (expressed as a fraction of expiratory time) gradually decreased with increasing minute ventilation during exercise in both sexes (P < 0.05), but the decrease was comparable between sexes (P > 0.05). CONCLUSION The primary finding of this study was that the pattern of respiratory muscle recruitment was different between sexes during incremental cycling, given that women displayed systematically faster rates, and greater magnitude, of net inspiratory and expiratory pressure-development compared with men at matched ventilations. Additionally, the duration of PIIA was similar in both women and men, which implies no difference in the pattern of transition from inspiration to expiration between sexes.

Respiratory Response to Underwater and Land‐based Cycling at the Matched Oxygen Uptake

Water immersion increases breathing effort against elevated hydrostatic pressure. Thus, aquatic exercise training may have a greater benefit for the respiratory function when compared to the same intensity of exercise performed on dryland. The purpose of this study was to investigate the effect of underwater cycling on the respiratory function and breathing pattern when compared to land-based cycling performed at the matched exercise intensity. Ten healthy men performed maximal graded exercise test and 15 minutes of incremental water-based cycling exercise (WE) and land-based cycling exercise (LE) on separate days. In WE, cycling began at 30 rpm, and the cadence was increased by 15 rpm every 5 minutes. 3 paddles were attached to the wheel of stationary bicycle to increase pedaling resistance. In LE, participants cycled continuously at 60 rpm for 15 minutes while wattage was adjusted to match oxygen uptake (VO2) to the WE condition. Using spirometry, respiratory function and respiratory muscle pressure were measured before and after cycling, and the magnitude of change between pre- and post- exercise was also measured. Breathing pattern was measured continuously during cycling. Water temperature and immersion level were kept at 31.5 ℃ and xiphoid appendix, respectively. VO2 duringcycling in water and on dryland was similar. Minute ventilation, inspiratory and expiratory volumes, and respiratory rate increased whereas, inspiratory and expiratory times decreased as the cycling intensity (VO2) increased (all P < 0.05). Respiratory rate was slightly higher at 60 rpm in WE than LE (27 ± 3 vs. 24 ± 3 bpm, P = 0.053). Inspiratory time was significantly higher at rest in WE than LE (1.4 ± 0.1 vs. 1.2 ± 0.0 sec, P < 0.05). After cycling exercise, change in the forced expiratory volume in one second and change in the peak expiratory flow were significantly lower in WE than LE (-0.04 ± 0.15 vs. 0.06 ± 0.10 L, P < 0.05. -0.37 ± 0.87 vs. 0.04 ± 0.63 L, P < 0.05, respectively). These data suggest that the respiratory and breathing responses were mostly similar during underwater and land-based cycling when VO2 is matched in both conditions. However, breathing may slightly be shallower during a higher-intensity aquatic cycling which may have chronic effects on respiratory function after multiple bouts of aquatic cycling for a longer term.

The Effects of using Deep Heat on Enhancing Aerobic Performance

Most studies have shown that athletes use deep heat cream for rehabilitative and pain-relief purposes for pre-, post- and during exercise. However, limited studies have indicated the effects of deep heat on enhancing aerobic performance. Purpose To determine whether the application of deep heat cream on the skin before exercise will allow individuals to prolong the duration of their aerobic activity. Methods Nine healthy male participants ((age: 23.78 ± 1.20 years, height: 1.71 ± 0.08 m, weight (WT): 65.53 ± 8.14 kg, body mass index (BMI): 22.43 ± 2.30 kg·m-2, 80% of maximal oxygen consumption(80%VO2max): 25.35 ± 10.32 mL·kg-1·min-1)) who engaged in aerobic exercise at least 3 times a week participated in this study. All participants underwent an incremental cycling test to determine VO2max. Subsequently, they completed two treatment tests – deep heat application (DH) and placebo cream application (PC). Each treatment required the participants to cycle at their 80%VO2max workload (175.56 ± 17.40 W) until volitional exhaustion. The time-to-exhaustion (TE) was recorded. Polar heart rate (HR) transmitters were used to measure HR and participants rated their rate of perceived exertion (RPE) using Borg's RPE scale. HR and RPE were recorded throughout both DH and PC. Using a power of 0.90, an a of 0.05, and an effect size of 0.9, it was determined that a minimum of 9 participants were required to test interaction effects. Results Results indicated no significant differences between both tests for last stage of HR (LSHR) and RPE (LSHR: DH: 170.00 ± 17.46 beats·min-1 vs. PC: 167.63 ± 20.09 beats·min-1, p = 0.63; RPE: DH: 18.88 ± 1.89 vs. PC: 18.25 ± 1.28, p = 0.42). There were positive significant correlations between WT and BMI (WT: 65.53 ± 8.14 kg vs. BMI: 22.43 ± 2.30 kg·m-2, r = 0.71, p = 0.03); DHLSHR and DHTE (DHLSHR: 172.44 ± 17.90 beats·min-1 vs. DHTE: 510.22 ± 231.66 secs, r = 0.85, p = 0.00); PCLSHR and PCTE (PCLSHR: 167.63 ± 20.09 beats·min-1 vs. PCTE: 391.67 ± 211.44 secs, r = 0.82, p = 0.01). There was also significant difference between DHTE and PCTE (DHTE: 510.22 ± 231.66 secs vs. PCTE: 391.67 ± 211.44 secs, p = 0.02). Conclusion The application of deep heat cream before exercise has shown to significantly improve endurance performance. Athletes or sports enthusiasts may consider using deep heat before exercise to achieve optimal endurance performance. More studies are needed to explore the benefits of the application of deep heat on exercise performance.

Thoracoabdominal asynchrony associates with exercise intolerance in fibrotic interstitial lung diseases.

The precise coordination of respiratory muscles during exercise minimizes work of breathing and avoids exercise intolerance. Fibrotic interstitial lung disease (f-ILD) patients are exercise-intolerant. We assessed whether respiratory muscle incoordination and thoracoabdominal asynchrony (TAA) occur in f-ILD during exercise, and their relationship with pulmonary function and exercise performance. We compared breathing pattern, respiratory mechanics, TAA and respiratory muscle recruitment in 31 f-ILD patients and 31 healthy subjects at rest and during incremental cycle exercise. TAA was defined as phase angle (PhAng) >20°. During exercise, when compared with controls, f-ILD patients presented increased and early recruitment of inspiratory rib cage muscle (p< 0.05), and an increase in PhAng, indicating TAA. TAA was more frequent in f-ILD patients than in controls, both at 50% of the maximum workload (42.3% vs. 10.7%, p= 0.01) and at the peak (53.8% vs. 23%, p= 0.02). Compared with f-ILD patients without TAA, f-ILD patients with TAA had lower lung volumes (forced vital capacity, p< 0.01), greater dyspnoea (Medical Research Council > 2 in 64.3%, p= 0.02), worse exercise performance (lower maximal work rate % predicted, p= 0.03; lower tidal volume, p= 0.03; greater desaturation and dyspnoea, p< 0.01) and presented higher oesophageal inspiratory pressures with lower gastric inspiratory pressures and higher recruitment of scalene (p< 0.05). Exercise induces TAA and higher recruitment of inspiratory accessory muscle in ILD patients. TAA during exercise occurred in more severely restricted ILD patients and was associated with exertional dyspnoea, desaturation and limited exercise performance.

Clinical evaluation of a novel subcutaneous lactate monitor

Lactate levels are commonly used as an indirect measure to assess metabolic stress in clinical conditions like sepsis. Dynamic lactate measurements are recommended to assess and guide treatment in patients with shock and other critical care conditions. A minimally invasive, continuous lactate monitor has potential to improve clinical decisions and patient care. The purpose of the study was to evaluate continuous lactate measurements of a novel enzymatic Continuous Lactate Monitor (CLM) developed in our laboratory. Lactate levels were monitored during incremental cycling exercise challenges as a tool for hyperlactatemia. Six healthy individuals 18–45 y/o (4 males, 2 females) participated in the study. CLM devices were inserted subcutaneously in the postero-lateral trunk below the renal angle, one hour before the exercise challenge. Each exercise challenge consisted of a 3 to 12-min warm up period, followed by up to 7, 4-min incremental workload bouts separated by rest intervals. Continuous lactate measurements obtained from CLM were compared with commercial lactate analyzer (Abbott iSTAT) measurements of venous blood (plasma) drawn from the antecubital vein. Blood was drawn at up to 25 time points spanning the duration of before exercise, during exercise, and up to 120 min post exercise. Area under the curve (AUC), and delay time were calculated to compare the CLM readings with plasma lactate concentration. Average plasma lactate concentration increased from 1.02 to 16.21 mM. Ratio of AUC derived from CLM to plasma lactate was 1.025 (0.990–1.058). Average dynamic delay time of CLM to venous plasma lactate was 5.22 min (2.87–10.35). Insertion sites examined 48 h after CLM removal did not show signs of side effects and none required medical attention upon examination. The newly developed CLM has shown to be a promising tool to continuously measure lactate concentration in a minimally invasive fashion. Results indicate the CLM can provide needed trends in lactate over time. Such a device may be used in the future to improve treatment in clinical conditions such as sepsis.

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.

Evaluation of the repeatability and reliability of the cross-training specific Fight Gone Bad workout and its relation to aerobic fitness

Cross-training is a high-intensity functional training (HIFT) with multiple workout modalities. Despite the increasing number of studies in HIFT, there is still no validated test to measure its specific performance. It would also be advisable to determine whether selected cross-training workouts can implement a stimulus corresponding to maximize aerobic work. For these reasons, the purpose of our study was to evaluate the repeatability and reliability of Fight Gone Bad (FGB) workout and to assess its relationship with aerobic fitness. Twenty-one cross-training participants (9 females) finished the study protocol which included three two-day measurement sessions separated by 10 days. During each session, participants had their body composition measured, and they performed two exercise tests. The first test was an incremental cycling test to measure aerobic fitness, and the second was a cross-training specific FGB workout performed the next day. Reliability and repeatability were calculated from the three measurements. The total FGB Score (FGBTOTAL) showed excellent reliability (ICC 0.9, SEM 6%). Moreover, FGBTOTAL was strongly correlated with aerobic fitness (i.e., time to exhaustion (Texh, R2 = 0.72), maximal workload (Wmax, R2 = 0.69), time to gas exchange threshold (TGET, R2 = 0.68), and peak oxygen uptake (VO2peak, R2 = 0.59). We also found that agreement between standardized FGB and standardized aerobic performance indices such as Texh, VO2peak, Wmax, maximum heart rate, TGET, and workload at gas exchange threshold was high by the Bland–Altman method. In conclusion, FGB is a reliable test that can be used in order to measure changes in cross-training performance caused by an intervention. Moreover, FGB is strongly correlated to aerobic fitness.

Situational interest impacts college students’ physical activity in a design-based bike exergame

BackgroundActive videogames or exergames have been used as an innovative way to promote physical activity (PA) among various populations. A player's interest in active videogames is associated with the fun and entertaining nature of the games and may trigger situational interest, thus increasing engagement. The goal of this study was to examine the impact of situational interest dimensions on college students’ PA when playing the design-based bike exergame Greedy Rabbit (Vescape, Berlin, Germany). MethodsSixty undergraduate students (age: 20.8 ± 1.3 years, mean ± SD, 18–25 years old; 51.7% males) were recruited from the kinesiology department of a university located in the southern region of Belgium. The participants were assigned to an experimental group (n = 41) or a control group (n = 19) based on an incremental cycling test. Students in the experimental group engaged in 1 session of Greedy Rabbit (Vescape) while students in the control group engaged in 1 session of a placebo version of Greedy Rabbit (Vescape). The length of the sessions ranged from 24 min to 31 min. ResultsResults for the control group indicated that the players’ PA metrics (cadence: F(19, 360) = 1.43, p = 0.11; heart rate: F(19, 360) = 1.16, p = 0.29; oxygen consumption: F(19, 360) = 0.83, p = 0.67) were stable during the exergame. Results for the experimental group demonstrated the effects of time on the players’ PA metrics and revealed significant associations between the change in the players’ situational interest dimensions and PA metrics (cadence: F(19, 800) = 26.30, p < 0.01; heart rate: F(19, 800) = 19.77, p < 0.01; oxygen consumption: F(19, 800) = 10.04, p < 0.01). ConclusionAn approach using a design-based exergame may be a relevant strategy for promoting levels of PA that yields positive health-related outcomes among college students.

Characteristics and reference values for cardiopulmonary exercise testing in the adult Chinese population – The Xiangya hospital exercise testing project (the X-ET project)

BackgroundReference values of cardiopulmonary exercise testing (CPX) vary with race/ethnicity. Chinese Americans are the fastest-growing racial/ethnic group in the United States. However, there is limited information about the reference values of cardiopulmonary exercise testing (CPX) variables in the Chinese population. MethodsAs part of the Xiangya Hospital Exercise Testing project (the X-ET project), this cross-sectional study screened 20,696 consecutive CPXs performed by 17,802 unique individuals at Xiangya Hospital of Central South University, China, from January 1, 2002, to December 31, 2019. A total of 964 unique healthy adults/tests (42% female) aged 49 ± 12 who completed a maximal ramp incremental CPX with cycle ergometry were included in this study. The reference values of primary CPX variables were expressed as the lower limit or upper limit of normal. Stepwise linear regression was used to fit the equations of key CPX variables. Predictive accuracy analysis for the equations with a comparison between present and previous studies were performed. ResultsPeak oxygen consumption (V̇O2), carbon dioxide production, ventilation/min, work rate, and V̇O2 at the anaerobic threshold were regressed on age, height, weight, and sex. These predictive equations showed good in- and out-sample predictive accuracy. Comparison with prior research revealed that prediction equations of peak V̇O2 resultant from studies in which populations were entirely or primarily Caucasian had overestimated our subjects' actual values. ConclusionThe reference values and predicted equations of CPX variables in this study may provide a more appropriate framework to interpret the response to maximal ramp incremental cycle ergometry in the Chinese adult population.

Validity and reproducibility of VO2 max testing in a respiration chamber.

The aim of this study was to investigate whether VO2max can be accurately measured in a respiration chamber. Thirty participants aged 23.4 ± 3.9 years with a wide range in VO2max were included. Participants performed four incremental cycle ergometer tests (VO2max) with a minimum of 5 days between tests. These tests consisted of one familiarization test with face mask, followed by two VO2max tests in the respiration chamber and one test with face mask in randomized order. Oxygen consumption and CO2 production were measured continuously using Omnical (Maastricht University, the Netherlands) gas analysis system. The mean VO2max was 3634 ± 766 ml, which resulted in mean VO2max per lean body mass of 60.8 ± 8.0 ml/kg. Repeated respiration chamber tests showed a high concordance, and no significant differences were detected between tests (Lin's concordance correlation coefficient (Rc) = 0.99; ∆70 ± 302 ml/min; p = .38). There was high concordance between the mean VO2max from both respiration chamber tests and the mean face mask tests, and no significant difference (Rc = 0.99; ∆41 ± 173 ml/min; p = .22) was observed. The Bland‐Altman plots showed no proportional bias between different tests. In conclusion, the respiration chamber has been found to be a valid and reproducible method for measuring VO2max. New research opportunities are possible in the respiration chamber, such as maximal exercise testing during 24‐hour measurements.

Relationship of characteristic duration and magnitude of the oscillatory breathing related with exercise functional capacity in patients with chronic heart failure

Objective: To find out the relationship between the duration and amplitude of oscillatory breathing (OB) and their exercise capacity in patients with chronic heart failure (CHF) we did this study. Methods: Two hundred and thirty-seven CHF patients performed a maximum incremental upright cycle ergometry cardiopulmonary exercise testing (CPET). Respiratory gas exchange was measured on a breath-by-breath basis throughout the test. OB was defined as 3 or more continuous cycle fluctuations of ventilation during CPET, and the amplitude of VE oscillations exceed 25% of concurrent mean value. The CHF patients with OB (OB+) were divided into 3 sub-groups according to their Peak VO2. Group1 (mild OB+) Peak VO2 of ≥16 ml/min/kg, group 2 (moderate OB+) Peak VO2 is between 12~16 ml/min/kg, group 3 (severe OB+) Peak VO2 ≤ 12 ml/(min·kg). Results: There were 78(32.6%) patients detected as OB+ in 237 CHF patients. Among OB+ patients, OB duration in s related negatively to Peak VO2 in mL/min/kg (r=-0.82), Peak VO2 in %pred (r=-0.65), VO2 at AT (r=-0.78), and related positively to VE/VCO2 at AT (r=0.61). Conclusion: OB duration is related negatively to exercise capacity of CHF patients.

Effects of Post-Exertional Malaise on Markers of Arterial Stiffness in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Background: Evidence is emerging that individuals with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) may suffer from chronic vascular dysfunction as a result of illness-related oxidative stress and vascular inflammation. The study aimed to examine the impact of maximal-intensity aerobic exercise on vascular function 48 and 72 h into recovery. Methods: ME/CFS (n = 11) with gender and age-matched controls (n = 11) were randomly assigned to either a 48 h or 72 h protocol. Each participant had measures of brachial blood pressure, augmentation index (AIx75, standardized to 75 bpm) and carotid-radial pulse wave velocity (crPWV) taken. This was followed by a maximal incremental cycle exercise test. Resting measures were repeated 48 or 72 h later (depending on group allocation). Results: No significant differences were found when ME/CFS were directly compared to controls at baseline. During recovery, the 48 h control group experienced a significant 7.2% reduction in AIx75 from baseline measures (p < 0.05), while the matched ME/CFS experienced no change in AIx75. The 72 h ME/CFS group experienced a non-significant increase of 1.4% from baseline measures. The 48 h and 72 h ME/CFS groups both experienced non-significant improvements in crPWV (0.56 ms−1 and 1.55 ms−1, respectively). Conclusions: The findings suggest that those with ME/CFS may not experience exercise-induced vasodilation due to chronic vascular damage, which may be a contributor to the onset of post-exertional malaise (PEM).

Cooper’s 12 min run test: Its validity in Indian swimmers and volleyball players

Objectives: VO2max is globally considered as the gold standard to evaluate the cardiorespiratory fitness that is an essential component to judge one’s aerobic fitness level. The present study was aimed to enumerate the validity for application of Cooper’s 12 min run test (CRT) in predicting VO2max among Indian swimmers and volleyball players. Materials and Methods: Swimmers (male = 66, female = 70) and volleyball players (male = 88, female = 81) were recruited by simple random sampling from reputed clubs of Kolkata. They were segregated into study and confirmatory groups. VO2max was determined by graded incremental cycle ergometer test followed by expired gas analysis and indirect CRT method. Results: Predicted VO2max (PVO2max) showed significant difference with the directly measured VO2max (VO2max) in study groups of both sports. Limits of agreement between PVO2max and VO2max proved inapplicability of current CRT protocol in studied populations. Modified population specific equations were computed from significant correlation of VO2max with distance covered in Cooper run test. Application of these norms in confirmatory groups revealed insignificant difference between PVO2max and VO2max in both genders. Conclusion: Modified equations are validated for application of CRT in evaluating VO2max in swimmers and volleyball players of both genders of Kolkata, India.

Differential Brain and Muscle Tissue Oxygenation Responses to Exercise in Tibetans Compared to Han Chinese

The Tibetans’ better aerobic exercise capacity at altitude remains ill-understood. We tested the hypothesis that Tibetans display better muscle and brain tissue oxygenation during exercise in hypoxia. Using near-infrared spectrometry (NIRS) to provide indices of tissue oxygenation, we measured oxy- and deoxy-hemoglobin ([O2Hb] and [HHb], respectively) responses of the vastus lateralis muscle and the right prefrontal cortex in ten Han Chinese and ten Tibetans during incremental cycling to exhaustion in a pressure-regulated chamber at simulated sea-level (air at 1 atm: normobaric normoxia) and 5,000 m (air at 0.5 atm: hypobaric hypoxia). Hypoxia reduced aerobic capacity by ∼22% in both groups (d = 0.8, p < 0.001 vs. normoxia), while Tibetans consistently outperformed their Han Chinese counterpart by ∼32% in normoxia and hypoxia (d = 1.0, p = 0.008). We found cerebral [O2Hb] was higher in Tibetans at normoxic maximal effort compared Han (p = 0.001), while muscle [O2Hb] was not different (p = 0.240). Hypoxic exercise lowered muscle [O2Hb] in Tibetans by a greater extent than in Han (interaction effect: p < 0.001 vs. normoxic exercise). Muscle [O2Hb] was lower in Tibetans when compared to Han during hypoxic exercise (d = 0.9, p = 0.003), but not during normoxic exercise (d = 0.4, p = 0.240). Muscle [HHb] was not different between the two groups during normoxic and hypoxic exercise (p = 0.778). Compared to Han, our findings revealed a higher brain tissue oxygenation in Tibetans during maximal exercise in normoxia, but lower muscle tissue oxygenation during exercise in hypoxia. This would suggest that the Tibetans privileged oxygenation of the brain at the expense of that of the muscle.

Determinants of Peak Fat Oxidation Rates During Cycling in Healthy Men and Women.

This study explored lifestyle and biological determinants of peak fat oxidation (PFO) during cycle ergometry, using duplicate measures to account for day-to-day variation. Seventy-three healthy adults (age range: 19-63 years; peak oxygen consumption [V˙O2peak]: 42.4 [10.1] ml·kg BM-1·min-1; n = 32 women]) completed trials 7-28 days apart that assessed resting metabolic rate, a resting venous blood sample, and PFO by indirect calorimetry during an incremental cycling test. Habitual physical activity (combined heart rate accelerometer) and dietary intake (weighed record) were assessed before the first trial. Body composition was assessed 2-7 days after the second identical trial by dual-energy X-ray absorptiometry scan. Multiple linear regressions were performed to identify determinants of PFO (mean of two cycle tests). A total variance of 79% in absolute PFO (g·min-1) was explained with positive coefficients for V˙O2peak (strongest predictor), FATmax (i.e the % of V˙O2peak that PFO occurred at), and resting fat oxidation rate (g·min-1), and negative coefficients for body fat mass (kg) and habitual physical activity level. When expressed relative to fat-free mass, 64% of variance in PFO was explained: positive coefficients for FATmax (strongest predictor), V˙O2peak, and resting fat oxidation rate, and negative coefficients for male sex and fat mass. This duplicate design revealed that biological and lifestyle factors explain a large proportion of variance in PFO during incremental cycling. After accounting for day-to-day variation in PFO, V˙O2peak and FATmax were strong and consistent predictors of PFO.

A pilot study investigating cortical haemodynamic and physiological correlates of exercise cognition in trained and untrained cyclists over an incremental self-paced performance test, while thinking aloud

ObjectivesFew studies have directly investigated changes in cortical haemodynamics during a self-paced interval endurance activity, while collecting conscious cognition and physiological performance data. This pilot study used functional Near Infrared Spectroscopy (fNIRS), while capturing conscious cognition using Think Aloud (TA) during an incremental paced cycling exercise. MethodsA mixed design was implemented with cycling expertise (untrained vs. trained) as the between groups variable and incremental self-paced stage (5 stages of increasing effort) and site (12 optodes across the PFC) as the within groups variables. Dependent measures were the changes in cortical O2Hb, and physiological indicators (% heart rate max (%HRmax), average power output (APO), peak power output (PPO), rate of perceived exertion (RPE) and blood lactate (Bla)) over time. Participants used TA throughout their second interval trial. ResultsTrained cyclists had higher APO and maximum power output (MPO) from stages 2–5, in addition to a greater increase in PPO over the whole trial. There were significant main effects of stage on %HRmax, Bla and RPE. Differences in cortical haemodynamics were found specifically in areas in the mid left and right PFC. TA data demonstrated that untrained participants verbalised more irrelevant information and feelings of pain and fatigue, in addition to both groups verbalising significantly more motivation-related thoughts during the final stage. ConclusionThis pilot is the first to capture changes in Cox, physiological measures and conscious cognition through the use of TA. We demonstrate the potential role of mid- PFC, and how conscious cognition may change over time. This study has implications for coaches and sport psychologists who may want to understand the cognitions of their athlete during an event and support low level athletes in developing a better understanding of the own cognitions.

Dyspnea during exercise and voluntary hyperpnea in women with obesity

Temporal responses of ratings of perceived breathlessness (RBP) during constant-load and incremental exercise, and during voluntary hyperpnea (EVH) were examined in women with obesity. Following 6 min of constant-load (60W) cycling, 34 women rated RPB≥4 (+DOE) and 22 women rated RPB≤2 (–DOE). Both groups completed an incremental cycling test and an EVH test at 40 and 60L/min; RPB was assessed each minute of incremental cycling and at the end of each EVH trial. RPB increased with ventilation during constant-load (+DOE: R2=0.86; –DOE: R2=0.82) and incremental (+DOE: R2=0.91; –DOE: R2=0.92) exercise, but + DOE had a greater y-intercept than –DOE (60W: -0.16±1.53 vs. -0.73±0.55; incremental: -0.50±1.40 vs. -1.71±0.84). Despite matching ventilation, RPB was greater in + DOE at baseline (0.97±1.14 vs. 0.14±0.28), 40L/min (2.50±1.43 vs. 0.98±0.91), and 60L/min (3.94±2.19 vs. 2.07±1.32) during EVH. These findings show that despite linear associations between RPB and ventilation during exercise and voluntary hyperpnea, breathlessness perception at a given ventilatory demand is heightened in +DOE compared with –DOE.