Moderate-intensity Cycling Research Articles

Circulating endotoxin and inflammation: associations with fitness, physical activity and the effect of a 6-month programme of cycling exercise during haemodialysis.

Intradialytic cycling (IDC) may provide cardiovascular benefits to individuals receiving haemodialysis, but the exact mechanism behind these improvements remains unclear. The primary aim of this study was to investigate the effect of a 6-month programme of IDC on circulating endotoxin (secondary analysis from the CYCLE-HD trial). Secondary aims were to investigate changes in circulating cytokines [interleukin-6 (IL-6), IL-10, tumour necrosis factor-α, C-reactive protein (CRP) and the IL-6:IL-10 ratio] and their associations with physical activity, fitness and cardiovascular outcomes. Participants were randomized to either a 6-month programme of IDC (thrice weekly, moderate intensity cycling at a rating of perceived exertion of 12-14) in addition to usual care (n = 46) or usual care only (control group; n = 46). Outcome measures were obtained at baseline and then again at 6 months. There was no significant (P = 0.137) difference in circulating endotoxin between groups at 6 months (IDC group: 0.34 ± 0.08 EU/mL; control group: 0.37 ± 0.07 EU/mL). There were no significant between-group differences in any circulating cytokine following the 6-month programme of IDC. Higher levels of physical activity and fitness were associated with lower levels of endotoxin, IL-6, CRP and IL-6:IL-10 ratio. Our data show no change in circulating endotoxin or cytokines following a 6-month programme of IDC. However, higher levels of physical activity outside of haemodialysis were associated with lower levels of inflammation.

Spleen Contraction During Step‐Transition Supine Cycling Exercise: Preliminary findings

The current literature suggests that the spleen plays a significant role during physiological stress like exercise or apnea, primarily due to its capacity to contract and release additional red blood cells (RBC) into the systemic circulation. Besides the RBC release, human spleen emptying is also associated with circulating platelets release. However, data on the circulating platelets release following acute exercise have not yet been examined thoroughly. This is especially important since the spleen platelet volume is ~20% larger compared to the volume of circulating platelets, and some authors suggest that increased spleen platelet concentration is associated with the greater risk of a cardiovascular or cerebrovascular event during exercise. The present study aims to explore the magnitude of spleen contraction during on-transient supine cycling exercise in healthy humans. We hypothesized that the spleen is capable of rapid contractions during on-transient cycling, thereby releasing an additional amount of both RBC and platelets into the systemic circulation. Such an increase in RBC count in particular may facilitate O2 transport, and result in faster oxygen kinetics during on transient supine cycling. Healthy, active volunteers (age= 22±3, V̇O2 max.= 48±5 mL·kg·min-1), completed three laboratory visits, including a detailed medical examination, resting ultrasound imaging of the spleen, V̇O2 max. test until voluntary exhaustion, and a supine step-transition test from 20 W to a moderate-intensity cycling power output (PO), corresponding to V̇O2 at 90% gas exchange threshold (GET). During the step-transitions breath-by-breath pulmonary oxygen uptake (V̇O2p), near-infrared spectroscopy derived muscle oxygenation, and beat-by-beat cardiovascular response (via Finapres) were continuously monitored. In parallel, minute by minute ultrasonic measurements of the spleen function were performed in successive, 3 sec. time frames. Blood samples were drawn from the antecubital vein before and immediately after the acute exercise intervention.Currently, six participants completed all study procedures. Compared to baseline readings, the largest spleen volume reduction (~40%) was observed during the 6th minute of cycling at 90% GET. Spleen volume recovered to baseline values after 20 minutes. Immediately after exercise cessation the mean RBC and platelet count increased significantly by 3.2% and 6.5%, respectively. In parallel, the V̇O2p was 46±10 sec, while the mean V̇O2 uptake was ~2.5 L·min-1. Secondary to these findings, transient rises in mean arterial pressure (MAP) and heart rate (HR), were observed during the step-transition exercise, with MAP and HR reaching the highest value of 110±4 mmHg and 149±2 bmp, respectively. In conclusion, these preliminary findings indicate that splenic contraction evoked by a series of on-transient cycling bouts at 90% GET results in a rapid increase in RBC and platelet count into the systemic circulation of healthy active individuals.

Psychological and psychophysiological mechanisms underlying the effects of meditation during moderate-intensity exercise

ABSTRACT The present experiment sought to further understanding of the psychological and psychophysiological mechanisms underlying the effects of a single session of audio-guided meditation during moderate-intensity cycling exercise. Twenty-four healthy participants were recruited. A portable EEG device was employed to investigate the cerebral responses associated with the effects of meditation on exercise. Psychological measures were administered at three timepoints during the exercise bout. Two experimental conditions (endurance meditation [EM] and catastrophic meditation [CM]) and a control condition (CO) were administered. Participants were asked to exercise for 8 min (2 min of warm-up performed at 20% below the first ventilatory threshold + 6 min of exercise performed at the first ventilatory threshold) at 60 rpm. The EEG signal from frontal electrode sites was decomposed using Morlet Complex Wavelets, and event-related perturbation was calculated to investigate changes in beta frequency associated with the cycling phase. The results indicate that EM was sufficiently potent to ameliorate exertion and enhance affect to a greater degree than CO and CM. The neural mechanisms underlying the effects of EM appear to be associated with increased beta activity in the right frontal regions. The results of this study also indicate that exertional fatigue can be modulated through an alternative route that is not reliant upon the use of dissociative thoughts and does not require motivation to be up-regulated.

Moderate intensity cycling is better than running on recovery of eccentric exercise-induced muscle damage

ObjectiveTo compare the effects of moderate intensity running and cycling on markers of exercise-induced muscle damage in men. Study designRandomized controlled trial. SettingLaboratory. ParticipantsThirty volunteers were randomized in three groups [running (RG; n = 10), cycling (CG; n = 10) and control (CON; n = 10)] and were evaluated at baseline, post 24, 48 and 72 h of knee extensors’ muscle damage protocol. CON performed passive recovery, while RG and CG performed active recovery immediately after the protocol, as well as 24 h and 48 h afterwards. Main outcomes(i) maximal voluntary isometric contraction (MVIC); (ii) delayed-onset muscle soreness (DOMS); (iii) plasma creatine kinase (CK) and lactate dehydrogenase (LDH) levels. ResultsNo group-by-time interaction was found in any outcome evaluated (p > 0.05). All groups presented decreases in MVIC and increases in DOMS (p < 0.001), without differences in CK and LDH. Compared with CON, exercise groups presented likely beneficial effects for LDH, while only CG had a likely beneficial effect for DOMS. Lastly, CG presented likely/very likely beneficial effects for MVIC and DOMS compared to RG. ConclusionAlthough the null hypothesis analysis did not find differences, the magnitude-based inference analysis suggested that moderate intensity cycling have likely beneficial effects on knee extensor muscle recovery after eccentric exercise protocol.

Multiple-day high-dose beetroot juice supplementation does not improve pulmonary or muscle deoxygenation kinetics of well-trained cyclists in normoxia and hypoxia

Dietary nitrate (NO3−) supplementation via beetroot juice (BR) has been reported to lower oxygen cost (i.e., increased exercise efficiency) and speed up oxygen uptake (VO2) kinetics in untrained and moderately trained individuals, particularly during conditions of low oxygen availability (i.e., hypoxia). However, the effects of multiple-day, high dose (12.4 mmol NO3− per day) BR supplementation on exercise efficiency and VO2 kinetics during normoxia and hypoxia in well-trained individuals are not resolved. In a double-blinded, randomized crossover study, 12 well-trained cyclists (66.4 ± 5.3 ml min−1∙kg−1) completed three transitions from rest to moderate-intensity (~70% of gas exchange threshold) cycling in hypoxia and normoxia with supplementation of BR or nitrate-depleted BR as placebo. Continuous measures of VO2 and muscle (vastus lateralis) deoxygenation (ΔHHb, using near-infrared spectroscopy) were acquired during all transitions. Kinetics of VO2 and deoxygenation (ΔHHb) were modeled using mono-exponential functions. Our results showed that BR supplementation did not alter the primary time constant for VO2 or ΔHHb during the transition from rest to moderate-intensity cycling. While BR supplementation lowered the amplitude of the VO2 response (2.1%, p = 0.038), BR did not alter steady state VO2 derived from the fit (p = 0.258), raw VO2 data (p = 0.231), moderate intensity exercise efficiency (p = 0.333) nor steady state ΔHHb (p = 0.224). Altogether, these results demonstrate that multiple-day, high-dose BR supplementation does not alter exercise efficiency or oxygen uptake kinetics during normoxia and hypoxia in well-trained athletes.

Reproducibility of Glucose Fluctuations Induced by Moderate Intensity Cycling Exercise in Persons with Type 1 Diabetes.

Aims The purpose was to assess the reproducibility of glucose changes during three sessions of standardized moderate intensity continuous training of cycling on an individual level in people with type 1 diabetes. Methods Twelve adults (six females) with type 1 diabetes performed three test sessions on an ergometer bicycle (30 min, 67% of predicted heart rate) on three different days. The participants were 36.5 (26.6-45.5) (median, IQR) years old, and their HbA1c was 65 ± 15 mmol/mol (mean ± SD). Two hours before the tests, the participants had a standard meal. Interstitial glucose (IG) and capillary glucose (CG) were measured using an iPro2 Medtronic continuous glucose monitor and the Bayer Contour XT-device, respectively. Prior to the test sessions, resting heart rate was measured using a digital blood pressure monitor to estimate the desired intensity of the exercise. Results The average within-participant relationship between the average slope in glucose during sessions 2 and 1 was in IG -0.29 (95% CI -1.11; 0.58) and in CG -0.04 (-0.68; 0.77). Between sessions 3 and 2, IG is 0.18 (-0.27; 0.64) and in CG 0.13 (-0.25; 0.55). Between sessions 3 and 1, IG was 0.06 (-0.57; 0.71) and in CG 0.06 (-0.39; 0.52). The results indicate low reproducibility at participant levels and remained unchanged after adjustment for baseline glucose values. Conclusion On an individual level, the glucose declines during three standardized sessions of PA were not associated with identical responses of the measured IG and CG levels. An overall anticipated decline of glucose concentrations was found in the moderate intensity cycling sessions. This highlights the importance of regular CG measurements during and after physical activity and awareness towards potential exercise-induced hypoglycemia in persons with type 1 diabetes.

Cognitive Effects of Aerobic Exercise in Alzheimer's Disease: A Pilot Randomized Controlled Trial.

Background:Aerobic exercise has shown inconsistent cognitive effects in older adults with Alzheimer’s disease (AD) dementia.Objective:To examine the immediate and longitudinal effects of 6-month cycling on cognition in older adults with AD dementia.Methods:This randomized controlled trial randomized 96 participants (64 to cycling and 32 to stretching for six months) and followed them for another six months. The intervention was supervised, moderate-intensity cycling for 20–50 minutes, 3 times a week for six months. The control was light-intensity stretching. Cognition was assessed at baseline, 3, 6, 9, and 12 months using the AD Assessment Scale-Cognition (ADAS-Cog). Discrete cognitive domains were measured using the AD Uniform Data Set battery.Results:The participants were 77.4±6.8 years old with 15.6±2.9 years of education, and 55% were male. The 6-month change in ADAS-Cog was 1.0±4.6 (cycling) and 0.1±4.1 (stretching), which were both significantly less than the natural 3.2±6.3-point increase observed naturally with disease progression. The 12-month change was 2.4±5.2 (cycling) and 2.2±5.7 (control). ADAS-Cog did not differ between groups at 6 (p = 0.386) and 12 months (p = 0.856). There were no differences in the 12-month rate of change in ADAS-Cog (0.192 versus 0.197, p = 0.967), memory (–0.012 versus –0.019, p = 0.373), executive function (–0.020 versus –0.012, p = 0.383), attention (–0.035 versus –0.033, p = 0.908), or language (–0.028 versus –0.026, p = 0.756).Conclusion:Exercise may reduce decline in global cognition in older adults with mild-to-moderate AD dementia. Aerobic exercise did not show superior cognitive effects to stretching in our pilot trial, possibly due to the lack of power.

Time course of changes in V̇o2peak and O2 extraction during ramp cycle exercise following HIIT versus moderate-intensity continuous training in type 2 diabetes.

In the present study, we assessed the time course of adaptations in peak oxygen uptake (V̇o2peak) and muscle fractional oxygen (O2) extraction (using near-infrared spectroscopy) following 12 wk of low-volume high-intensity interval training (HIIT) versus moderate-intensity continuous endurance training (MICT) in adults with uncomplicated type 2 diabetes (T2D). Participants with T2D were randomly assigned to MICT (n = 12, 50 min of moderate-intensity cycling) or HIIT (n = 9, 10 × 1 min at ∼90% maximal heart rate) or to a nonexercising control group (n = 9). Exercising groups trained three times per week and measurements were taken every 3 wk. The rate of muscle deoxygenation (i.e., deoxygenated hemoglobin and myoglobin concentration, Δ[HHb+Mb]) profiles of the vastus lateralis muscle were normalized to 100% of the response, plotted against % power output (PO), and fitted with a double linear regression model. V̇o2peak increased (P < 0.05) by week 3 of MICT (+17%) and HIIT (+8%), with no further significant changes thereafter. Total increases in V̇o2peak posttraining (P < 0.05) were 27% and 14%, respectively. The %Δ[HHb+Mb] versus %PO slope of the first linear segment (slope1) was reduced (P < 0.05) beyond 3 wk of HIIT and MICT, with no further significant changes thereafter. No changes in V̇o2peak or slope1 were observed in the control group. Low-volume HIIT and MICT induced improvements in V̇o2peak following a similar time course, and these improvements were likely, at least in part, due to an improved microvascular O2 delivery.

Substrate-Specific Respiration of Isolated Skeletal Muscle Mitochondria after 1 h of Moderate Cycling in Sedentary Adults.

Skeletal muscle mitochondria have dynamic shifts in oxidative metabolism to meet energy demands of aerobic exercise. Specific complexes oxidize lipid and nonlipid substrates. It is unclear if aerobic exercise stimulates intrinsic oxidative metabolism of mitochondria or varies between substrates. We studied mitochondrial metabolism in sedentary male and female adults (n = 11F/4M) who were free of major medical conditions with mean ± SD age of 28 ± 7 yr, peak aerobic capacity of 2.0 ± 0.4 L·min-1, and body mass index of 22.2 ± 2 kg·m-2. Biopsies were collected from the vastus lateralis muscle on separate study days at rest or 15 min after exercise (1 h cycling at 65% peak aerobic capacity). Isolated mitochondria were analyzed using high-resolution respirometry of separate titration protocols for lipid (palmitoylcarnitine, F-linked) and nonlipid substrates (glutamate-malate, N-linked; succinate S-linked). Titration protocols distinguished between oxidative phosphorylation and leak respiration and included the measurement of reactive oxygen species emission (H2O2). Western blotting determined the protein abundance of electron transfer flavoprotein (ETF) subunits, including inhibitory methylation site on ETF-β. Aerobic exercise induced modest increases in mitochondrial respiration because of increased coupled respiration across F-linked (+13%, P = 0.08), N(S)-linked (+14%, P = 0.09), and N-linked substrates (+17%, P = 0.08). Prior exercise did not change P:O ratio. Electron leak to H2O2 increased 6% increased after exercise (P = 0.06) for lipid substrates but not for nonlipid. The protein abundance of ETF-α or ETF-β subunit or inhibitory methylation on ETF-β was not different between rest and after exercise. In sedentary adults, the single bout of moderate-intensity cycling induced modest increases for intrinsic mitochondrial oxidative phosphorylation that was consistent across multiple substrates.

Effects of ascorbic acid supplementation on immune status in healthy women following a single bout of exercise

This study was designed to determine the effects of ascorbic acid (AA) supplementation on immune status following a single bout of exercise. In a crossover design, 20 healthy sedentary women performed 30 min moderate-intensity cycling with (1000AA) or without (0AA) ingesting 1000 mg of AA daily for 1 week. Blood samples were taken immediately before, immediately after and 24 h post-exercise to determine the oxidative stress markers, immunophenotyping of peripheral blood lymphocytes and neutrophil phagocytic function. Moderate-intensity exercise in participants ranged in age from 21 to 23 years, showed no significant changes in oxidative stress markers in both cohorts. Plasma total creatine kinase was increased immediately after exercise and returned to baseline at 24 h post-exercise in both cohorts. Participants ingesting 1000 mg AA demonstrated significant higher level of plasma AA at pre-exercise and post-exercise as compared with the same time point in 0AA group. White blood cell and absolute neutrophil counts were increased immediately after exercise in both cohorts. Exercise resulted in increased lymphocyte count, CD4 + and CD8 + T cell counts immediately after exercise (p < 0.05) in 0AA group. AA supplement mitigated effects of exercise on CD4 + T cells. No significant change in neutrophil phagocytic function were observed when incubated with low or high concentrations of Candida albicans in both cohorts. These results suggested that a single bout of moderate-intensity exercise caused muscle injury with increased absolute CD4 + and CD8 + T cell counts, accompanied by a transient increase in neutrophil count, while their phagocytic function was not changed. However, a short-term AA supplementation does not show beneficial effects on exercise-induced changes in leukocyte subpopulations.

Changes in the Laterality of Oxygenation in the Prefrontal Cortex and Premotor Area During a 20-Min Moderate-Intensity Cycling Exercise.

A recent study based on near-infrared spectrometry (NIRS) showed that a single session of moderate-intensity exercise increases the cortical oxyhemoglobin (O2Hb) level. However, changes in the laterality of O2Hb throughout such exercises remain unknown. In the present study, we evaluated changes in the laterality of O2Hb in the prefrontal cortex (PFC) and premotor area (PMA) during moderate-intensity cycling for 20 min. Twelve healthy volunteers performed the exercise at 50% of the maximal oxygen consumption after a 3-min rest period. O2Hb levels in the right (R-) and left (L-) PFC and PMA were measured using multichannel NIRS and averaged every 5 min during the exercise period, and the laterality index (LI) for each 5-min period was calculated. LI for PFC showed significant changes in each period (first, second, third, and fourth periods: -0.40±0.21, -0.03±0.12, 0.14±0.15, and 0.16±0.10, respectively; p<0.05), whereas that for PMA showed no significant changes (-0.07±0.09, 0.23±0.08, 0.17±0.12, and 0.19±0.09, respectively; p=0.12). These findings suggest that the laterality of cortical oxygenation in PFC of healthy, young individuals changes during moderate-intensity exercise for 20min, thus providing an insight into the mechanisms underlying exercise-induced improvements in brain function.

Caffeine mouth rinse enhances performance, fatigue tolerance and reduces muscle activity during moderate-intensity cycling.

We investigated the effects of caffeine mouth rinse on endurance performance, muscle recruitment (i.e., electromyographic activity of the vastus lateralis and rectus femoris), rating of perceived effort and heart rate. Twelve physically-active healthy men cycled at 80% of their respiratory compensation point until task failure. The participants rinsed their mouths for 10 seconds with placebo (PLA, 25 mL of a solution composed of non-caloric mint essence) or caffeine (CAF, 25 mL of 1.2% of anhydrous caffeine concentration with non-caloric mint essence) every 15 minutes of exercise. Time until exhaustion increased 17% (effect size = 0.70) in CAF compared to PLA (p = 0.04). The wavebands of low-frequency electromyographic activity (EMG) of the vastus lateralis and rectus femoris was lower in CAF group than PLA at 50% of the time until exhaustion (p = 0.04). The global EMG signal was lower in CAF group than PLA at 100% of the time until exhaustion (p = 0.001). The rating of perceived effort pooled was higher in CAF mouth rinse (p = 0.001) than PLA group. No effect was found on the heart rate between the groups (p > 0.05). Caffeine mouth rinse increases endurance performance, rating of perceived effort and decreases muscle activity during a moderate-intensity exercise.

Prior exercise enhances skeletal muscle microvascular blood flow and mitigates microvascular flow impairments induced by a high-glucose mixed meal in healthy young men.

Exercise, insulin-infusion and low-glucose mixed-nutrient meal ingestion increases muscle microvascular blood flow which in part facilitates glucose delivery and disposal. In contrast, high-glucose ingestion impairs muscle microvascular blood flow which may contribute to impaired postprandial metabolism. We investigated the effects of prior cycling exercise on postprandial muscle microvascular blood flow responses to a high-glucose mixed-nutrient meal ingested 3 and 24h post-exercise. Prior exercise enhanced muscle microvascular blood flow and mitigated microvascular impairments induced by a high-glucose mixed meal ingested 3h post-exercise, and to a lesser extent 24h post-exercise. High-glucose ingestion 3h post-exercise leads to greater postprandial blood glucose, non-esterified fatty acids, and fat oxidation, and a delay in the insulin response to the meal compared to control. Effects of acute exercise on muscle microvascular blood flow persist well after the cessation of exercise which may be beneficial for conditions characterized by microvascular and glycaemic dysfunction. Exercise, insulin-infusion and low-glucose mixed-nutrient meal ingestion lead to increased muscle microvascular blood flow (MBF), whereas high-glucose ingestion impairs MBF. We investigated whether prior cycling exercise could enhance postprandial muscle MBF and prevent MBF impairments induced by high-glucose mixed-nutrient meal ingestion. In a randomized cross-over design, eight healthy young men ingested a high-glucose mixed-nutrient meal (1.1g glucose/kg body weight; 45% carbohydrate, 20% protein and 35% fat) after an overnight fast (no-exercise control) and 3h and 24h after moderate-intensity cycling exercise (1h at 70-75% ). Skeletal muscle MBF, measured directly by contrast-enhanced ultrasound, was lower at 60min and 120min postprandially compared to baseline in all conditions (P<0.05), with a greater decrease occurring from 60min to 120min in the control (no-exercise) condition only (P<0.001). Despite this meal-induced decrease, MBF was still markedly higher compared to control in the 3h post-exercise condition at 0min (pre-meal; 74%, P=0.004), 60min (112%, P=0.002) and 120min (223%, P<0.001), and in the 24h post-exercise condition at 120min postprandially (132%, P<0.001). We also report that in the 3h post-exercise condition postprandial blood glucose, non-esterified fatty acids (NEFAs), and fat oxidation were substantially elevated, and the insulin response to the meal delayed compared to control. This probably reflects a combination of increased post-exercise exogenous glucose appearance, substrate competition, and NEFA-induced insulin resistance. We conclude that prior cycling exercise elicits long-lasting effects on muscle MBF and partially mitigates MBF impairments induced by high-glucose mixed-nutrient meal ingestion.

The effect of acute, moderate intensity indoor cycling on the temporal resolution of human vision system, measured by critical fusion frequency.

Critical fusion frequency (CFF) reflects the basic temporal function of the visual system and therefore is a good measure of its performance. CFF has been implemented in psychological and pharmacological studies to evaluate cognitive functions. The influence of abnormal environmental conditions, such as physical exercise, has been recently explored. Previous studies have presented alterations of cognitive processes due to acute exercise. However, the duration of the effect after the end of exercise has not been investigated. This evaluation is important especially in reference to long‐term conclusions on the effect of training on CFF as an improvement of cognition. The main goal of this study was to check whether a stimulatory effect of acute submaximal physical exercise on CFF among non‐experienced cyclists persists over time. Moreover, we asked whether this effect differs between areas of visual field. CFF thresholds from 15 volunteers were measured by means of an automated medical perimeter PTS 910 (Bogdani) before, immediately after the end, and 30 min after the end of two sessions (training and rest). During rest, CFF did not change significantly, but we observed an increased CFF immediately after training. Interestingly, this increase was maintained 30 min after the end of exercise in fovea. A greater decrease of CFF during rest was observed for lower than for upper hemifield. Our results suggest that an acute, moderate‐intensity cycling improved CFF in non‐experienced cyclists, with the duration of the effect depending on eccentricity. The possible visual hemifield asymmetries of CFF changes over time will be further investigated.

Acute physiological and perceptual responses to moderate intensity cycling with different levels of blood flow restriction.

The aim of this study was to compare: i) the physiological and perceptual responses of low-load exercise [(moderate intensity exercise (MI)] with different levels of blood flow restriction (BFR), and ii) MI with BFR on the bike with high intensity (HI) exercise without BFR. The protocol involved large muscle mass exercise at different levels of BFR, and this differentiates our study from others. Twenty-one moderately trained males (age: 24.6 ± 2.4 years; VO2peak: 47.2 ± 7.0 ml.kg-1.min-1, mean ± sd) performed one maximal graded exercise test and seven 5-min constant-load cycling bouts. Six bouts were at MI [40% peak power (Ppeak), 60%VO2peak], one without BFR and five with different levels of BFR (40%, 50%, 60%, 70%, 80% of estimated arterial occlusion pressure). The HI bout (70%Ppeak, 90%VO2peak) was without BFR. Oxygen uptake (VO2), heart rate (HR), blood lactate (BLa), rate of perceived exertion (RPE), and tissue oxygen saturation (TSI) were recorded. Regardless of pressure, HR, BLa and RPE during MI-BFR were higher compared to MI (p < 0.05, ES: moderate to very large), and TSI reduction was greater in MI-BFR than MI (p < 0.05, ES: moderate to large). The responses of VO2, HR, BLa, RPE and TSI induced by the different levels of BFR in MI-BFR were similar. Regardless of pressure, the responses of VO2, HR, BLa and RPE induced by MI-BFR were lower than HI (p < 0.05), except for TSI. TSI change was similar between MI-BFR and HI. It appears that BFR equal to 40% of arterial occlusion pressure is sufficient to reduce TSI when exercising with a large muscle mass.

Central and Peripheral Postexercise Blood Pressure and Vascular Responses in Young Adults with Obesity.

Adults with obesity are at an increased risk of incident hypertension. Regular aerobic exercise is recommended for the prevention and treatment of hypertension, but whether young adults with obesity exhibit impaired postexercise blood pressure (BP) and vascular responses remains unclear. We tested the hypothesis that young adults with obesity exhibit attenuated postexercise hypotension (PEH) and postexercise peripheral vasodilation compared with young adults without obesity. Thirty-six normotensive adults without and with obesity (11 men and 7 women per group) underwent measurements of brachial and central BP, and leg blood flow (Doppler ultrasound) at baseline and at 30, 60, and 90 min after acute 1-h moderate-intensity cycling. Leg vascular conductance (LVC) was calculated as flow/mean arterial pressure. Both groups exhibited similar brachial and central PEH (peak change from baseline, -2 and -4 mm Hg for brachial and central systolic BPs, respectively, for both groups; time effect, P < 0.05). Both groups also exhibited postexercise peripheral vasodilation, assessed via LVC (time effect, P < 0.05), but its overall magnitude was smaller in young adults with obesity (LVC change from baseline, +47% ± 37%, +29% ± 36%, and +20% ± 29%) compared with young adults without obesity (LVC change from baseline, +88% ± 58%, +59% ± 54%, and +42% ± 51%; group effect, P < 0.05). Although obesity did not impair PEH after acute moderate-intensity exercise, young adults with obesity exhibited smaller postexercise peripheral vasodilation compared with young adults without obesity. Collectively, these findings have identified evidence for obesity-induced alterations in the peripheral vasculature after exercise.

Cognitive effects of acute aerobic exercise: Exploring the influence of exercise duration, exhaustion, task complexity and expectancies in endurance-trained individuals

ABSTRACT The cognitive effects of acute aerobic exercise were investigated in endurance-trained individuals. On two occasions, 21 cyclists; 11 male (VO2max: 57 ± 9 mL·kg−1·min−1) and 10 female (VO2max: 51 ± 9 mL·kg−1·min−1), completed 45 min of fixed, moderate-intensity (discontinuous) cycling followed by an incremental ride to exhaustion. Cognitive function was assessed at Baseline, after 15 and 45 min of exercise (15EX and 45EX) and at Exhaustion using a 4-Choice Reaction Time (CRT) test and the Stroop test (Incongruent and Congruent Reaction Time [RT]). A sham capsule was administered on one occasion to determine whether the cognitive response to exercise was robust to the influence of a placebo. CRT, Congruent RT and Incongruent RT decreased (improved) at 15EX, 45EX and Exhaustion compared to Baseline (p’s<0.005). While CRT and Congruent RT were faster at 45EX than 15EX (p’s<0.020), Incongruent RT was not (p= 1.000). The sham treatment did not affect cognition. When performed at a moderate-intensity, longer duration exercise (up to 45 min) may improve cognition to a greater extent than shorter duration exercise; however, the magnitude of improvement appears to decrease with increasing task complexity. HI/EE performed following a sustained bout of dehydrating activity may not impair cognition.

Heat shock protein 90 modulates cutaneous vasodilation during an exercise-heat stress, but not during passive whole-body heating in young women.

Heat shock protein 90 (HSP90) modulates exercise‐induced cutaneous vasodilation in young men via nitric oxide synthase (NOS), but only when core temperature is elevated ~1.0°C. While less is known about modulation of this heat loss response in women during exercise, sex differences may exist. Further, the mechanisms regulating cutaneous vasodilation can differ between exercise‐ and passive‐heat stress. Therefore, in 11 young women (23 ± 3 years), we evaluated whether HSP90 contributes to NOS‐dependent cutaneous vasodilation during exercise (Protocol 1) and passive heating (Protocol 2) and directly compared responses between end‐exercise and a matched core temperature elevation during passive heating. Cutaneous vascular conductance (CVC%max) was measured at four forearm skin sites continuously treated with (a) lactated Ringers solution (control), (b) 178 μM Geldanamycin (HSP90 inhibitor), (c) 10 mM L‐NAME (NOS inhibitor), or (d) combined 178 μM Geldanamycin and 10 mM L‐NAME. Participants completed both protocols during the early follicular (low hormone) phase of the menstrual cycle (0–7 days). Protocol 1: participants rested in the heat (35°C) for 70 min and then performed 50 min of moderate‐intensity cycling (~55% VO2peak) followed by 30 min of recovery. Protocol 2: participants were passively heated to increase rectal temperature by 1.0°C, comparable to end‐exercise. HSP90 inhibition attenuated CVC%max relative to control at end‐exercise (p < .05), but not during passive heating. While NOS inhibition and combined HSP90 + NOS inhibition attenuated CVC%max relative to control for both protocols (all p < .05), they did not differ from each other. We show that HSP90 modulates cutaneous vasodilation NOS‐dependently during exercise in young women, with no effect during passive heating, despite a similar NOS contribution.

Natural killer cell mobilization and egress following acute exercise in men with prostate cancer

What is the central question of this study? What are the characteristics of the NK cell response following acute moderate-intensity aerobic exercise in prostate cancer survivors and is there a relationship between stress hormones and NK cell mobilization? What is the main finding and its importance? NK cell numbers and proportions changed similarly between prostate cancer survivors and controls following acute exercise. Consecutive training sessions can likely be used without adverse effects on the immune system during prostate cancer treatment. Prostate cancer treatment affects multiple physiological systems, although the immune response during exercise has been minimally investigated. The objective was to characterize the natural killer (NK) cell response following acute exercise in prostate cancer survivors. Prostate cancer survivors on androgen deprivation therapy (ADT) and those without (PCa) along with non-cancer controls (CON) completed a moderate intensity cycling bout. NK cells were phenotyped before and 0, 2 and 24h after acute exercise using flow cytometry. CD56 total NK cell frequency increased by 6.2% at 0h (P<0.001) and decreased by 2.5% at 2h (P<0.01) with similar findings in CD56dim cells. NK cell counts also exhibited a biphasic response. Independent of exercise, ADT had intracellular interferon γ (IFNγ) expression that was nearly twofold higher than CON (P<0.01). PCa perforin expression was reduced by 11.4% (P<0.05), suggesting these cells may be more prone to degranulation. CD57- NK cells demonstrated increased perforin and IFNγ frequencies after exercise with no change within the CD57+ populations. All NK and leukocyte populations returned to baseline by 24h. NK cell mobilization and egress with acute exercise appear normal, as cell counts and frequencies in prostate cancer survivors change similarly to CON. However, lower perforin proportions (PCa) and higher IFNγ expression (ADT) may alter NK cytotoxicity and require further investigation. The return of NK cell proportions to resting levels overnight suggests that consecutive training sessions can be used without adverse effects on the immune system during prostate cancer treatment.

The Effects of Acute Moderate and High Intensity Exercise on Memory.

Acute cardiovascular exercise can enhance correct remembering but its impact upon false remembering is less clear. In two experiments, we investigated the effect of acute bouts of exercise on correct and false remembering using the Deese–Roediger–McDermott (DRM) memory test. In Experiment 1, healthy adults completed quiet rest or moderate intensity cycling prior to the memory test. In Experiment 2, a similar sample completed moderate intensity running, high intensity sprints, or a period of quiet rest prior to the memory test. In Experiment 1, acute moderate intensity exercise increased short-term correct, but not false, recall. Experiment 2 replicated these findings but also found an acute bout of high intensity exercise had no impact upon either type of short-term recall. Acute moderate intensity exercise, but not acute high intensity exercise, can improve short-term correct recall without an accompanying increase in false recall potentially through processing of contextually specific information during encoding.