Bicycle Exercise Research Articles

Healthy urban blue space design: Exploring the associations of blue space quality with recreational running and cycling using crowdsourced data

Urban blue space offers substantial health benefits by encouraging population physical activity. Despite much evidence on the nature-health nexus, the relationship between blue space and recreational exercises remains under-studied, limiting the realisation of health benefits in blue space design. Using crowdsourced data, including volunteered geographic information and street view image data, this study investigates the associations of blue space quality with recreational running and cycling in Rotterdam, the Netherlands. Results show that recreational exercise levels on street segments vary based on the blue space type and design. Compared to inland canals and rivers, small-scale recreational waterbodies are more conducive to running but not cycling, while both activities tend to cluster around the Nieuwe Maas River. Interestingly, the Water View Index shows a general negative association with both activities after adjusting for the blue space type. Besides the waterbody characteristics, eye-level environmental factors, including higher Green View Index, lower building density, more diverse land use, greater connected street network and fewer traffic elements, are associated with more running and cycling exercises. Results for visual complexity and neighbourhood population composition are mixed depending on the exercise type. These findings are further translated into spatial design patterns for developing exercise-supportive and health-promoting blue spaces.

Muscle fatigue, pedalling technique and the slow component during cycling.

Above the first lactate threshold, the steady-state is delayed or prevented due to the slow component ( ). This phenomenon has been associated with muscle fatigue, but evidence for a causal relationship is equivocal. Moreover, little is known about the contribution of pedalling technique adjustments to during fatiguing cycling exercise. Eleven participants completed constant power trials at 10% above the second lactate threshold. Muscle fatigue was assessed, utilizing femoral nerve stimulation and instrumented pedals, while , quadriceps oxygenation, electromyography (EMG) and pedal force components were measured. Correlations between physiological and mechanical variables were estimated at group and individual levels. Group correlations revealed moderate values for with quadriceps twitch force (r=-0.51) and muscle oxygenation (r=-0.52), while weak correlations were observed for EMG amplitude (r=0.26) and EMG mean power frequency (r=-0.16), and with pedalling mechanical variables such as peak total downstroke force (r=-0.16), minimum total upstroke force (r=-0.16) and upstroke index of effectiveness (r=0.16). The findings here align with prior literature reporting significant correlations between the magnitude of muscle fatigue and that of , although there was large interindividual variability for all the reported correlations. Considering the heterogeneity in the data, it is difficult to determine therelative impact of pedalling technique adjustments on overall, but the present study opens the possibility that in some cases, increases in secondary to technical adjustments may be 'superimposed' on the underlying .

Nebulized fentanyl does not improve exercise capacity or dyspnoea in fibrosing interstitial lung disease.

Exercise intolerance and exertional dyspnoea are hallmarks of fibrosing interstitial lung disease (FILD) and are associated with worse prognosis and quality of life. Activation of pulmonary vagal afferents influences the ventilatory pattern and contributes to the sensation of dyspnoea. We tested the hypothesis that nebulized fentanyl, which might attenuate aberrant pulmonary afferent activity in FILD, reduces ventilation and dyspnoea while extending exercise endurance time (EET). In this randomized, single-blind, placebo-controlled study, eight FILD patients (two males, 71±6years of age) performed incremental cardiopulmonary cycle exercise tests following nebulization of either fentanyl citrate (100 µg) or 0.9% saline. Previous work indicated that this dose was unlikely to produce central effects. Comparisons between treatment conditions at rest were undertaken using Student's paired t-test, and exercise data were evaluated with two-way ANOVA with repeated measures. Dyspnoea was assessed using the Borg dyspnoea scale. Resting respiratory variables were not different following treatment with fentanyl and saline; however, resting heart rate was lower following fentanyl (P=0.002) and remained lower throughout exercise compared with placebo (P=0.008). Fentanyl did not increase EET (placebo 334±117s vs. fentanyl 348±126s, P=0.250) although overall minute ventilation was reduced slightly (mean difference: -0.97 L/min, P=0.022). There were no differences in ratings of dyspnoea intensity or unpleasantness between the conditions either at rest or at end-exercise. Nebulized fentanyl did not improve EET or exercise dyspnoea but did decrease minute ventilation during exercise, although the extent of this reduction appears clinically insignificant. These findings suggest that nebulized fentanyl is unlikely to offer significant benefits for enhancing exercise capacity in FILD.

Effects of low and high dietary nitrate intake on human saliva, plasma and skeletal muscle nitrate and nitrite concentrations and their functional consequences

Dietary nitrate (NO3−) supplementation has been shown to reduce blood pressure (BP), improve exercise performance, and alter the oral microbiome. Following a “control” diet (CON), we manipulated dietary NO3− intake to examine the effect of a short-term (7-day) low NO3− diet (LOW) followed by a 3-day high NO3− diet (HIGH), compared to a 7-day standard (STD) NO3− diet followed by HIGH, on saliva, plasma, and muscle [NO3−] and nitrite ([NO2−]), BP, and cycling exercise performance in healthy young adults. We also examined the effect of LOW on the oral microbiome. Saliva [NO3−] and [NO2−], and plasma [NO3−] were significantly lower than CON following LOW (all P < 0.05) but there was no change in plasma [NO2−] or muscle [NO3−] and [NO2−] (all P > 0.05). Following HIGH, saliva and plasma [NO3−] and [NO2−], and muscle [NO3−], were significantly elevated above CON, LOW and STD (all P < 0.05), but there was no difference between CON-LOW-HIGH and CON-STD-HIGH (P < 0.05). BP and exercise performance were not altered following LOW (P > 0.05). HIGH significantly reduced systolic and diastolic BP compared to CON when preceded by STD (both P < 0.05) but not when preceded by LOW (P > 0.05). Peak (+4 %) and mean (+3 %) power output during sprint cycling was significantly improved following HIGH (both P < 0.05), with no differences between CON-LOW-HIGH and CON-STD-HIGH (both P > 0.05). LOW altered the oral microbiome composition, including decreases in relative abundances of phylum Proteobacteria and genus Neisseria. The findings indicate that a short-term low NO3− diet lowers plasma but not skeletal muscle [NO3−]. The maintenance of plasma [NO2−] and muscle [NO3−] and [NO2−] following LOW may be indicative of their importance to biological functions, including BP regulation and exercise performance.

Effects of acetazolamide on exercise performance in patients with COPD going to high altitude: randomised controlled trial

BackgroundIn patients with chronic obstructive pulmonary disease (COPD), preventive treatment with acetazolamide reduces adverse health effects during altitude travel. We investigated whether preventive acetazolamide treatment modifies exercise performance in COPD patients going to high altitude.MethodsIn this randomized, double-blind trial, lowlanders with COPD, FEV1 40–80%predicted, were assigned to acetazolamide (375 mg/24 h) or placebo treatment starting 24 h before ascent and while staying at 3100 m. Patients performed progressive cycling exercise to exhaustion at 760 m, before taking the study drug, and within 4 h after arrival at 3100 m. Primary outcome was the maximal power output (Wmax). ClinicalTrials.govNCT03177837.Results103 patients (32 women), mean ±sdage 57.2±8.1y, FEV1 66±11% predicted, were included in per protocol analyses. In 53 patients receiving acetazolamide, Wmax and oxygen uptake (V'O2max) at 760 m and 3100 m were 105±40 and 91±40watts, and 18.0±6.8 and 15.5±6.8 ml·min−1·kg−1(p&lt;0.001, both changes). Corresponding Wmax and V'O2max in 50 patients receiving placebo were 107±41 and 97±41watts, and 18.9±7.0 and 17.2±7.0 ml·min−1·kg−1(p&lt;0.001, both changes). Between-group differences (95%CI) in altitude-induced Wmax-changes were −3.0 watts (−8.7 to +2.7, p=0.305) and in V'O2max-changes were −0.8 ml·min−1·kg−1(−2.1 to +0.5, p=0.213). Acetazolamide mitigated the altitude-induced reduction of end-exercise PaO2by 0.7kPa (0.1 to 1.3, p=0.016). At 3100 m, maximal work rate with respiratory exchange ratio ≤1 was greater with acetazolamide than with placebo by 10.1 watts (4.0 to 16.2, p=0.022).ConclusionsIn lowlanders with COPD, preventive treatment with acetazolamide did not modify the altitude-induced reduction in maximal work rate. However, acetazolamide enhanced arterial oxygenation and submaximal, moderate-intensity work capacity compared to placebo.

Vascular limitations in blood pressure regulation with age in women: Insights from exercise and acute cardioselective β-blockade.

Younger women rely on altering cardiac output ( ) to regulate blood pressure (BP). In contrast, older women rely more on altering vascular tone. However, evidence suggests that the ability to alter systemic vascular conductance (SVC) is diminished in older women. In the present study, cardioselective β-blockade was utilized to diminish the relative contribution of to BP regulation and thereby evaluate age-related vascular limitations in women at rest and during large muscle dynamic exercise. Younger (n=13, mean age 26.0 years) and older (n=14, mean age 61.8 years) healthy women performed submaximal bouts of semi-recumbent cycling exercise at varying intensities while receiving an intravenous infusion of esmolol, a β1-antagonist, or saline control in a repeated-measures crossover design. was attenuated during esmolol infusion, with greater reductions during exercise (moderate, -1.0 (95% CI, -1.6 to -0.5)L/min, P<0.001; heavy, -2.0 (95% CI, -2.6 to -1.5)L/min, P<0.001) than seated rest (-0.5 (95% CI, -1.1 to 0.0)L/min, P=0.048), and this reduction was not significantly different between age groups (P=0.122). Older women exhibited a greater attenuation in mean arterial pressure (MAP) during esmolol (-7 (95% CI, -9 to -4) mmHg, P<0.001) relative to younger women (-2 (95% CI, -5 to 0) mmHg, P=0.071). These changes coincided with a greater reduction of SVC in the younger women during esmolol (-15 (95% CI, -20 to -10)mL/min/mmHg, P<0.001) compared to older women (-3 (95% CI, -9 to 2)mL/min/mmHg, P=0.242). Together, these findings provide evidence that older, postmenopausal women have a diminished ability to adjust SVC in order to regulate MAP.

Cardiorespiratory Responses to Exercise in Hypobaric versus Normobaric Hypoxia: A Randomized, Single-Blind, Crossover Study.

There is controversy whether there are meaningful physiological differences between hypobaric (HH) and normobaric hypoxia (NH). This study aimed to compare the cardiorespiratory responses to acute HH and NH under strictly controlled conditions. We hypothesized no differences at rest and during submaximal exercise, whereas during maximal exercise, a higher maximal ventilation (V̇Emax), peripheral oxygen saturation (SpO2) and maximal oxygen consumption (V̇O2max) in HH than in NH. In a randomized, single-blind, crossover design, eight young healthy subjects (three females) were studied in an environmental chamber in which either the barometric pressure (HH) or the inspired oxygen fraction (NH) was reduced to the equivalent of ~4000 m altitude. Measurements were taken at rest, during submaximal (moderate and high intensity) and maximal cycling exercise. All resting parameters were similar between HH and NH, except for a lower root mean square of the successive R-R interval differences in HH (p < 0.05). SpO2 was 2% higher in HH at all exercise intensities (p < 0.05). During submaximal exercise, minute ventilation was similar between HH and NH. However, HH yielded a 7% lower tidal volume during moderate-intensity exercise (p < 0.05) and a lower respiratory exchange ratio during high-intensity exercise (p < 0.01). V̇Emax and V̇O2max were 11% and 6% higher in HH, respectively (p < 0.01 for both). SpO2 at maximal exercise was positively correlated with V̇Emax, V̇Emax/V̇O2max and V̇O2max. The higher V̇O2max found in HH than in NH can be attributed to the higher V̇Emax counteracting desaturation at maximal exercise. Conversely, submaximal SpO2 improved in HH through mechanisms other than increased ventilation. These findings are likely due to respiratory muscle unloading in HH, which operated through different mechanisms depending on exercise intensity.

Acute partial sleep deprivation attenuates blood pressure responses to cycling exercise.

Exaggerated blood pressure (BP) responses during exercise are independently associated with future development of hypertension. Partial sleep deprivation (PSD) can increase 24-h ambulatory BP, but the effects on exercise BP are unclear. We hypothesized that acute PSD would augment the BP response to constant load cycling exercise and a 20-min time trial. Twenty-two healthy adults (22 ± 3 yr old; 13 males; V̇o2peak, 43.6 ± 8.2 mL·kg-1·min-1) completed a randomized crossover trial in which they either slept normally (normal sleep-wake schedule for each participant) or sleep was partially deprived (early awakening, 40% of normal sleep duration). Each participant completed a 12-min warm-up consisting of two 6-min steps (step 1, 62 ± 25 W; step 2, 137 ± 60 W) followed by a 20-min time trial on a cycle ergometer. PSD did not alter power output during the 20-min time trial [(control vs. PSD) 170 ± 68 vs. 168 ± 68 W, P = 0.65]. Systolic BP did not differ during step 1 of the warm-up (141 ± 15 vs. 137 ± 12 mmHg, P = 0.39) but was lower following PSD during step 2 (165 ± 21 vs. 159 ± 22 mmHg, P = 0.004) and the 20-min time trial (171 ± 20 vs. 164 ± 23 mmHg, P < 0.001). These results were maintained when peak oxygen uptake (V̇o2peak) was included as a covariate. Systolic BP responses were modulated by sex (time × visit × sex interaction P = 0.03), with attenuated systolic BP during the warm-up and the 20-min time trial in males but not in females. In contrast to our hypothesis, acute PSD attenuates systolic BP responses during constant load and 20-min time trial cycling exercise; however, these observations appear to be primarily driven by changes in males.NEW & NOTEWORTHY A single night of partial sleep deprivation (PSD) can increase ambulatory blood pressure (BP) the following day. Despite this phenomenon, the present study found that acute PSD attenuates systolic BP responses to both constant load cycling and a 20-min cycling time trial in young healthy adults. Interestingly, the attenuated systolic BP responses following PSD appeared to be modulated by sex such that attenuations were observed in males but not in females.

Skeletal muscle myosin heavy chain fragmentation as a potential marker of protein degradation in response to resistance training and disuse atrophy.

We examined how resistance exercise (RE), cycling exercise and disuse atrophy affect myosin heavy chain (MyHC) protein fragmentation. The 1boutRE study involved younger men (n=8; 5±2years of RE experience) performing a lower body RE bout with vastus lateralis (VL) biopsies being obtained prior to and acutely following exercise. With the 10weekRT study, VL biopsies were obtained in 36 younger adults before and 24h after their first/naïve RE bout. Participants also engaged in 10weeks of resistance training and donated VL biopsies before and 24h after their last RE bout. VL biopsies were also examined in an acute cycling study (n=7) and a study involving 2weeks of leg immobilization (n=20). In the 1boutRE study, fragmentation of all MyHC isoforms (MyHCTotal) increased 3h post-RE (∼200%, P=0.018) and returned to pre-exercise levels by 6h post-RE. Interestingly, a greater magnitude increase in MyHC type IIa versus I isoform fragmentation occurred 3h post-RE (8.6±6.3-fold vs. 2.1±0.7-fold, P=0.018). In 10weekRT participants, the first/naïve and last RE bouts increased MyHCTotal fragmentation 24h post-RE (+65% and +36%, P<0.001); however, the last RE bout response was attenuated compared to the first bout (P=0.045). Although cycling exercise did not alter MyHCTotal fragmentation, ∼8% VL atrophy with 2weeks of leg immobilization increased MyHCTotal fragmentation (∼108%, P<0.001). Mechanistic C2C12 myotube experiments indicated that MyHCTotal fragmentation is likely due to calpain proteases. In summary, RE and disuse atrophy increase MyHC protein fragmentation. Research into how ageing and disease-associated muscle atrophy affect these outcomes is needed. HIGHLIGHTS: What is the central question of this study? How different exercise stressors and disuse affect skeletal muscle myosin heavy chain fragmentation. What is the main finding and its importance? This investigation is the first to demonstrate that resistance exercise and disuse atrophy lead to skeletal muscle myosin heavy chain protein fragmentation in humans. Mechanistic in vitro experiments provide additional evidence that MyHC fragmentation occurs through calpain proteases.

Whole body sweat rate prediction: indoor treadmill and cycle ergometer exercise.

This article describes the development and validation of accurate whole body sweat rate prediction equations for individuals performing indoor cycle ergometer and treadmill exercise, where power output can be measured or derived from simple inputs. For cycle ergometry, 112 trials (67 participants) were used for model development and another 56 trials (42 participants) for model validation. For treadmill exercise, 171 trials (67 participants) were used for model development and another 95 trials (63 participants) for model validation. Trials were conducted over a range of dry-bulb temperature (20°C to 40°C), relative humidity (14% to 60%), and exercise intensity (∼40% to 85% of peak aerobic power) conditions, which were matched between model development and model validation. Whole body sweat rates were measured, and proprietary prediction models were developed (accounting for all relevant biophysical factors) and then validated. For model validation, mean absolute error for predicted sweating rate was 0.01 and 0.02 L·h-1 for cycle and treadmill trials, respectively. The 95% confidence intervals were modest for cycle ergometer (+0.25 and -0.22 L·h-1) and treadmill exercise (+0.33 and -0.29 L·h-1). The accounted for variance between predicted and measured values was 92% and 78% for cycle and treadmill exercise, respectively. Bland-Altman analysis indicated that zero and one predicted value exceeded the a priori acceptable level of agreement (equivalent to ±2% of total body mass in 3 h) for cycle and treadmill exercise, respectively. There were fewer trials with female subjects, but their values did not differ from those expected for males. This is the foremost study to develop and validate whole body sweat rate prediction equations for indoor treadmill and cycle ergometer exercise of moderate to high intensity. These prediction equations are publicly available for use (https://sweatratecalculator.com).NEW & NOTEWORTHY This study presents the development of new proprietary whole body sweat rate prediction models for people exercising indoors on a cycle ergometer or treadmill using simple input parameters and delivered through a publicly available online calculator: https://sweatratecalculator.com. In an independent validation group, the predictive models for both indoor cycling and treadmill exercise were accurate across moderate to high exercise intensities in temperate to hot conditions. These equations will enable individualized hydration management during physical training and exercise physiology experiments.

Rating of perceived exertion as a tool for managing exercise intensity during pregnancy: a scoping review

ObjectiveDuring pregnancy, international guidelines recommend ≥150 min of moderate-intensity aerobic physical activity per week, with an intensity perceived as fairly light to somewhat hard on the Borg Rating of Perceived...

Leg cycling efficiency is unaltered in healthy aging regardless of sex or training status.

Muscular efficiency during exercise has been used to interrogate aspects of human muscle energetics, including mitochondrial coupling and biomechanical efficiencies. Typically, assessments of muscular efficiency have involved graded exercises. Results of previous studies have been interpreted to indicate a decline in exercise efficiency with aging owing to decreased mitochondrial function. However, discrepancies in variables such as exercise stage duration, cycling cadence, and treadmill walking mechanics may have affected interpretations of results. Furthermore, recent data from our lab examining the ATP to oxygen ratio (P:O) in mitochondrial preparations isolated from NIA mouse skeletal muscle showed no change with aging. Thus, we hypothesized that delta efficiency (Δ€) during steady-rate cycling exercise would not be altered in older healthy subjects compared with young counterparts regardless of biological sex or training status. Young (21-35 yr) and older (60-80 yr) men (n = 21) and women (n = 20) underwent continual, progressive leg cycle ergometer tests pedaling at 60 RPM for three stages (35, 60, 85 W) lasting 4 min. Δ€was calculated as: (Δ work accomplished/Δ energy expended). Overall, cycling efficiencies were not significantly different in older compared with young subjects. Similarly, trained subjects did not exhibit significantly different exercise efficiencies compared to untrained. Moreover, there were no differences between men and women. Hence, our results obtained on healthy young and older subjects are interpreted to mean that previous reports of decreased efficiency in older individuals were attributable to metabolic or biomechanical comorbidities, not aging per se.NEW & NOTEWORTHY Muscular power is reduced, but the efficiency of movement is unaltered in healthy aging.

Assessing the repeatability of expiratory flow limitation during incremental exercise in healthy adults.

We sought to determine the repeatability of EFL in healthy adults during incremental cycle exercise. We hypothesized that the repeatability of EFL would be "strong" when assessed as a binary variable (i.e., absent or present) but "poor" when assessed as a continuous variable (i.e., % tidal volume overlap). Thirty-two healthy adults performed spirometry and an incremental cycle exercise test to exhaustion on two occasions. Standard cardiorespiratory variables were measured at rest and throughout exercise, and EFL was assessed by overlaying tidal expiratory flow-volume and maximal expiratory flow-volume curves. The repeatability of EFL was determined using Cohen's κ for binary assessments of EFL and intraclass correlation (ICC) for continuous measures of EFL. During exercise, n = 12 participants (38%) experienced EFL. At peak exercise, the repeatability of EFL was "minimal" (κ = 0.337, p = 0.145) when assessed as a binary variable and "poor" when measured as a continuous variable (ICC = 0.338, p = 0.025). At matched levels of minute ventilation during high-intensity exercise (i.e., >75% of peak oxygen uptake), the repeatability of EFL was "weak" when measured as a binary variable (κ = 0.474, p = 0.001) and "moderate" when measured as a continuous variable (ICC = 0.603, p < 0.001). Our results highlight the day-to-day variability associated with assessing EFL during exercise in healthy adults.

Identifying abnormal exertional breathlessness in COPD: comparing mMRC and CAT with CPET

Chronic obstructive pulmonary disease (COPD) management is guided by the respiratory symptom burden, assessed using the modified Medical Research Council (mMRC) scale and/or COPD Assessment Test (CAT). What is the ability of mMRC and CAT to detect abnormally high exertional breathlessness on incremental cardiopulmonary cycle exercise testing (CPET) in people with COPD? Analysis of people aged ≥40 years with post-bronchodilator FEV1/FVC<0.70 and ≥10 smoking pack-years from the Canadian Cohort Obstructive Lung Disease study. Abnormal exertional breathlessness was defined as a breathlessness (Borg 0-10) intensity rating > upper limit of normal (ULN) at the symptom-limited peak of CPET using normative reference equations. We included 318 people with COPD (40% women), age 66.5±9.3 years (mean±SD), FEV1 79.5±19.0%predicted; 26% had abnormally low exercise capacity (V'O2peak <lower limit of normal). Abnormally high exertional breathlessness was present in 24%, including 9% and 11% of people with mMRC=0 and CAT<10, respectively. A mMRC≥2 and CAT≥10 was most specific (95%) to detect abnormal exertional breathlessness, but had low sensitivity of only 12%. Accuracy for all scale cut-offs or combinations was <65%. Compared with 'true negatives', people with abnormal exertional breathlessness but low mMRC and/or CAT scores ('false negatives') had worse self-reported and physiological outcomes during CPET, were more likely to have physician-diagnosed COPD, but were not more likely to have any respiratory medication (37% versus 30%; mean difference 6.1%; 95% confidence interval -7.2 to 19.4; p=0.36). In COPD, mMRC and CAT have low concordance with CPET and fail to identify many people with abnormally high exertional breathlessness.

Reliability Of A Cognitive Test Battery Pre And Post Maximal Cycling Exercise

Reliability Of A Cognitive Test Battery Pre And Post Maximal Cycling Exercise

Relationships between morphological factors and heat extraction from the upper arm using liquid cooling garment

Astronauts wear liquid perfused garments inside their outer spacesuits for regulating body temperature. The present study explored relationships between local heat production from the upper arm and body morphology while wearing liquid perfused sleeve. Heat extraction from the upper arm of 19 subjects (8 males and 11 females) during three different exercise modes (running at 6–8 km∙h−1, cycling at 40–55 W, and arm ergometer at 10–20 W) and rest has been investigated. The total body fat (27.5 ± 7.2%), body mass index (24.4 ± 2.7 kg·m−2), arm surface area (589 ± 90 cm2), and arm volume (1300 ± 300 mL) were considered as covariates. Subjects wore a liquid perfused sleeve over the upper arm (left) with the water inlet temperature of 24.0 ± 0.3 °C and the heat extraction was calculated using the water flow rate and temperature differences. Heat extraction from the upper arm showed no significant differences among the three exercises. During cycling, there was a negative relationship between heat extraction and total body fat (r = − 0.527, P < 0.05). Heat extraction was more related to the arm volume (P < 0.05) than the surface area of the upper arm, which was significant only for the male group in the cycling mode. For the female group, heat extraction was related to upper arm temperature in the cycling and arm exercise modes (for both exercises P < 0.05). These results can be applied to improve liquid cooling garments for astronauts, considering their body morphology and sex.

Heart rate response and recovery in cycle exercise testing - normal values and association with mortality.

Chronotropic incompetence and impaired heart rate (HR) recovery are related to mortality. Guidelines lack specific reference values for HR recovery. We defined normal values and studied blunted HR response and recovery, and mortality risk. We included 9,917 subjects (45% females) aged 18-85 years who performed a cycle exercise test. We defined normal values for peak HR, HR reserve, and HR recovery at 1 and 2 minutes (HRR1 and HRR2) based on individuals apparently healthy (N=2,242). Associations between blunted HR indices (<5th percentile) and mortality over a median follow-up of 8.6 years were analysed using Cox regression and competing risk analysis. All HR indices were age-dependent and independent predictors of all-cause and CV mortality. The 5th percentiles of HR reserve, HRR1, and HRR2 correlated weakly with existing reference values. HR recovery variables were the strongest predictors of all-cause mortality (HRR1, hazard ratio 1.70 [95% confidence interval, 1.49-1.94] and HRR2, 1.57 [1.37-1.79]), including in subjects with normal exercise capacity (HRR1, 1.96 [1.61-2.39] and HRR2, 1.76 [1.46-2.12]). Combining HR indices appeared to increase the risk of all-cause (HRR1 and HRR2, 1.96 [1.68-2.29] and peak HR and HRR1, 1.87 [1.56-2.23]) and CV mortality, although no specific combination was superior for predicting CV mortality. All HR variables were age-dependent and associated with all-cause and CV mortality. Blunted HR recovery variables were the strongest predictors of all-cause mortality, even in subjects with normal exercise capacity. Combined blunted HR indices appeared to add prognostic value.

The Impact of Exercise Intensity and Sex on Endogenous Ghrelin Levels and Appetite in Healthy Humans.

Ghrelin circulates in acylated (AG) and deacylated (DAG) forms, which are known to affect appetite. Although acute exercise has been shown to modulate ghrelin levels, data on the impact of exercise intensity on AG and DAG levels and their effects on appetite are sparse and primarily limited to males. To investigate the effect of exercise intensity and sex on ghrelin levels and appetite in untrained humans. Eight males (age: 43.1 ± 10.9 years; body mass index [BMI]: 22.2 ± 1.7 kg/m2; peak oxygen consumption [VO2peak]: 36.3 ± 6.4 mL/kg/min) and 6 females (age: 32.2 ± 11.1 years; BMI: 22.7 ± 1.0 kg/m2; VO2peak: 29.2 ± 4.0 mL/kg/min) completed a maximal graded cycle ergometer lactate threshold (LT)/VO2peak test. These data were used to determine the exercise intensity on 3 subsequent randomized control or calorically matched cycle exercise bouts: (1) CON, no exercise; (2) MOD, the power output at LT; (3) HIGH, the power output associated with 75% of the difference between LT and VO2peak. Perception of appetite was analyzed using visual analog scales. Females had higher levels of total ghrelin (TG) (P = .03) and DAG (P = .01) at baseline than males. Both groups exhibited reduced DAG levels in HIGH compared with MOD and CON (P < .0001-.004); however, only females had significantly reduced AG in HIGH (P < .0001). Hunger scores were higher in MOD than in CON (P < .01). High-intensity may be superior to moderate-intensity exercise for reducing ghrelin levels and modifying hunger, and sex may impact this response.

Effects of two types of distractions on ratings of perceived exertion and affective response during acute high-intensity cycling exercise for fair cardiorespiratory fitness level in men

Effects of two types of distractions on ratings of perceived exertion and affective response during acute high-intensity cycling exercise for fair cardiorespiratory fitness level in men

Impact of the Menstrual Cycle on the Cardiovascular and Ventilatory Responses During Exercise in Normoxia and Hypoxia.

Citherlet, Tom, Antoine Raberin, Giorgio Manferdelli, Nicolas Bourdillon, and Grégoire P Millet. Impact of the menstrual cycle (MC) on the cardiovascular and ventilatory responses during exercise in normoxia and hypoxia. High Alt Med Biol. 00:00-00, 2024. Introduction: Ovarian hormones influence several physiological functions in women. This study investigated how the hormonal variations across the menstrual cycle (MC) impact cardiovascular and ventilatory responses during rest and moderate exercise in normobaric hypoxia. Methods: Thirteen eumenorrheic women were tested during the early follicular (Fol1), late follicular (Fol2), and mid-luteal (Lut3) phases with measurement of hormonal levels. Heart rate (HR) variability, blood pressure, and baroreflex sensitivity (BRS) were evaluated at rest in normoxia. Ventilation (VE), peripheral oxygen saturation, and HR were monitored at rest and during moderate-intensity cycling exercise in hypoxia (FiO2 = 14%). Results: Despite expected hormone level variations, no significant changes were observed across the MC in HR variability (root mean square of successive differences; 64 (95% confidence interval [47, 81]) at Fol1, 54 [42, 66] at Fol2, 60 [44, 77] ms at Lut3), blood pressure (mean blood pressure; 85 [79, 90]), 87 [81, 93]), 84 [77, 92] mmHg), BRS (26 [17, 36], 28 [20, 35], 23 [17, 29] ms/mmHg), VE (rest: 8.9 [7.9, 9.8], 9.5 [9.0, 9.9], 9.0 [8.1, 9.9]; exercise: 53 [41, 66], 51.1 [36.4, 65.7], 54.4 [34.0, 74.8] l/min), peripheral oxygen saturation (rest: 89.8 [87.4, 92.1], 91.9 [88.7, 95.0], 90.2 [87.8, 92.6]; exercise: 80.5 [77.4, 83.5], 84.4 [80.4, 88.3], 81.9 [78.3, 85.4] %) HR (rest: 69.7 [60.2, 79.1], 70.8 [63.2, 78.3], 70.5 [64.0, 77.0]; exercise: 148 [136, 160], 146 [132, 161], 146 [132, 160] bpm), and cycling efficiency (0.17 [0.16, 0.18], 0.17 [0.13, 0.21], 0.16 [0.15, 0.18] %) (all p > 0.05). Discussion: From a practical point of view, there is no strong evidence of any usefulness of monitoring hormonal variations and the MC phases for women exercising in hypoxia.