Low-intensity Cycling Research Articles

Physiological responses to low-intensity stationary cycling with intermittent positive and negative pressure an exploratory study

Background: This study evaluated the physiological responses to intermittent positive and negative pressure (IPNP) in 17 healthy, recreationally active individuals (10 males, average age 33.1 years, mean BMI 26.1 kg/m²) during stationary, upright cycling. Methods: We assessed acute IPNP effects on heart rate variability (HRV), blood pressure, and cardiovascular responses during moderate-intensity exercise. Participants engaged in two exercise modalities: Monark cycle ergometry (Mc) and cycling with IPNP, ranging from ±15 to ±25 Mbar. Results: Results indicated normal physiological responses in heart rate and systolic blood pressure (SBP) from rest to peak exercise in both modalities. A non-significant difference in SBP was observed during Mc compared to IPNP. Significant differences in mean arterial pressure were noted during recovery from IPNP cycling, highlighting a distinct cardiovascular response. HR increased in both conditions during exercise, with a more pronounced increase during Mc. Comfort and perceived exertion revealed no significant differences between the two modalities, indicating the potential acceptability of IPNP therapies. Conclusion: The study provides valuable insights into cardiovascular dynamics during stationary cycling with intermittent positive and negative pressure and highlights key physiological responses that warrant further investigation.

Exercise-induced sweating decreases 24-h sodium balance compared to rest in recreational exercisers

Daily sodium intake in England is ∼3.3 g/day(1), with government and scientific advice to reduce intake for cardiovascular health purposes having varying success(2). Eccrine sweat is produced during exercise or exposure to warm environments to maintain body temperature through evaporative cooling. Sweat is primarily water, but also contains appreciable amounts of electrolytes, particularly sodium, meaning sweat sodium losses could reduce daily sodium balance without the need for dietary manipulation. However, the effects of sweat sodium losses on 24-h sodium balance are unclear.Fourteen active participants (10 males, 4 females; 23 ± 2 years, 45 ± 9 mL/kg/min) completed a preliminary trial and two 24-h randomised, counterbalanced experimental trials. Participants arrived fasted for baseline (0-h) measures (blood/urine samples, blood pressure, nude body mass) followed by breakfast and low-intensity intermittent cycling in the heat (∼36⁰C, ∼50% humidity) to turnover ∼2.5% body mass in sweat (EX), or the same duration of room temperature seated rest (REST). Further blood samples were collected post-EX/REST (1.5-3 h post-baseline). During EX, sweat was collected from 5 sites and water consumed to fully replace sweat losses. During REST, participants drank 100 mL/h. Food intake was individually standardised over the 24-h, with bottled water available ad-libitum. Participants collected all urine produced over the 24-h and returned the following morning to repeat baseline measures fasted (24-h). Sodium balance was estimated over the 24-h using sweat/urine losses and dietary intake. Data were analysed using 2-way ANOVA followed by Shapiro-Wilk and paired t-tests/Wilcoxon signed-rank tests. Data are mean (standard deviation).Dietary sodium intake was 2.3 (0.3) g and participants lost 2.8 (0.3) % body mass in sweat (containing 2.5 (0.9) g sodium). Sodium balance was lower for EX (-2.0 (1.6) g vs -1.0 (1.6) g; P = 0.022), despite lower 24-h urine sodium losses in EX (1.8 (1.2) g vs 3.3 (1.7) g; P = 0.001). PostEX/REST blood sodium concentration was lower in EX (137.6 (2.3) mmol/L vs 139.9 (1.0) mmol/L; P = 0.002) but did not differ at 0-h (P = 0.906) or 24-h (P = 0.118). There was no difference in plasma volume change (P = 0.423), urine specific gravity (P = 0.495), systolic (P = 0.324) or diastolic (P = 0.274) blood pressure between trials over the 24-h. Body mass change over 24-h was not different between trials (REST +0.25 (1.10) %; EX +0.40 (0.68) %; P = 0.663).Sweat loss through low-intensity exercise resulted in a lower sodium balance compared to rest. Although urine sodium output reduced with EX, it was not sufficient to offset exercise-induced sodium losses. Despite this, body mass, plasma volume and blood sodium concentration were not different between trials, suggesting sodium may have been lost from non-osmotic sodium stores. This suggests sweat sodium losses could be used to reduce sodium balance, although longer studies are required to confirm this thesis.

On the characterization of patterning in spruce budworm time-series data

I outline the “definitional problem” in forest insect outbreak analytics and show how it is related to the “counting problem” in dendroentomology and the “forecasting problem” in forest insect population dynamics, through the ubiquitous presence of non-stationary complex periodicity. Using real-world examples from the spruce budworm ( Choristoneura fumiferana Clem.) system, I show that regardless how outbreak patterning is characterized—whether by peak impact, cycle frequency, interval duration, or interval severity—the distribution in pattern attributes appears to be extremely variable, regardless how the data are processed through definitional filters. I show that this extreme variability is an unavoidable and key feature of the system’s dynamics and argue that it needs to be viewed as an object of study, instead of a nuisance problem to be swept under the rug. The single biggest opportunity for rapid gains in spruce budworm predictive ecology is determining the environmental and ecological factors that separate high-intensity from low-intensity outbreak cycling.

Effect of low-intensity aerobic cycling ergometer on ability to perform activity of daily living of patients with myasthenia gravis in RSUD Dr. Soetomo Surabaya

Background and objectives. Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction causing fluctuating skeletal muscle weakness and fatigue that result in increased restrictions on physical activity, affecting the patient's ability to perform daily activities in the family, social, and work environment. The MG-ADL scale is an assessment of the ability of the daily activities of MG patients that does not require equipment or special skills for the examiner and can be done in a short time. This study analyzes the effect of low intensity aerobic exercise cycle ergometer on the ability to perform daily activities of MG patients. Materials and methods. Twenty-two MG patients, MGFA class IIa and IIb, aged 18–59, participated in this study. The subjects were randomly divided into a treatment group and a control group. The treatment group received aerobic cycle ergometer exercise for 30 minutes, three times per week, for eight weeks. Both groups were educated to continue medication from neurology, perform physical activity as usual, and breathing exercises. Assessment of MG-ADL performed before and after intervention. Results. There was an improvement in scores on breathing and lower limb function in the treatment group. There was significant decrease in MG-ADL scores at the intervention group (p = 0.000) with large effect size (1.09). The comparison of MG-ADL scores between groups showed a significant value (p = 0.009) with a large effect size (1.24). Conclusion. Low intensity aerobic exercise cycle ergometer for 8 weeks improves the ability to perform ADL in MG patient.

The effect of low-intensity intradialytic cycling aerobic exercise on cognitive function in patients undergoing continuous hemodialysis

Background. End-stage renal disease (ESRD) patients often experience neurological complications. Mounting evidence suggests cognitive impairment associated with end-stage renal disease is likely related to vascular disruption in the brain, particularly in white matter integrity. Hemodialysis is an independent risk factor for mild cognitive decline (MCD) of ESRD patients and have serious implications for the quality of life. Intradialysis training is the most ideal choice for hemodialysis patients, because not requiring extra time and the patient is also under the supervision of a doctor when doing the exercises. Method. Eighteen patients with end-stage renal disease (ESRD) were randomized into two groups: a treatment group and a control group, with 9 patients in each group. The treatment group participated in low-intensity aerobic exercise on a cycle ergometer, consisting of two 30-minute sessions per week for 12 weeks. Both groups were instructed to continue their regular hemodialysis and medication regimen. MoCA-INA scores were measured before the intervention and again after 12 weeks for both groups. Comparisons of MoCA-INA scores were made within each group as well as between the two groups before and after the 12-week intervention. Results. In the treatment group, the MoCA-INA scores showed a significant improvement from baseline to after the intervention (p < 0.001; effect size = 1.88). In contrast, the control group did not exhibit a significant change in MoCA-INA scores (p = 0.468). Additionally, there was a significant difference in the change in MoCA-INA scores between the treatment and control groups after 12 weeks of intervention (p = 0.001).

The Effect of Low-Intensity Interval Exercise with Blood Flow Restriction on Plasma Cardiac Troponin: A Cross-Design Trial.

Low-intensity training with blood flow restriction (BFR) training could induce endurance adaptations, its impact on myocardial markers is still unclear compared to training without BFR. Consequently, the influence of low-intensity interval exercise with and without BFR and high-intensity interval exercise (HIIE) on cardiac troponin was determined in this study. Twelve physically active males between 18 and 26 years volunteered as participants. The participants completed 3 exercise tests in random order, which included 40% VO2max low-intensity cycling without BFR (group L), 40% VO2max low-intensity cycling with BFR set at 60% limb occlusion pressure (LOP) (group B), and 80% VO2max high-intensity cycling without BFR (group H). Participant muscle oxygen, blood flow, oxygen uptake, heart rate (HR), perceived exertion (RPE) rating, and pain levels were determined before and after exercise, after cuff inflation, and pre- and post-each exercise. Moreover, before each protocol, immediately after the exercises, and 3-4 hours after each exercise, elbow vein blood samples were collected to evaluate lactate (LA) and high-sensitivity cardiac troponin T (cTnT). Increased LA was recorded after exercise by the individuals in group H, which was more significant than in group B. Moreover, group B documented a more significant LA increment than group L (P < .05). The peak cTnT of groups B and H after exercise was significantly higher (P < .05). Furthermore, the increase was more significant than the values recorded by group L (P < .05). The present study demonstrated that low-intensity interval exercise combined with BFR could cause cTnT elevations compared to training without BFR. The increase was similar to HIIE protocols.

The effects of combining visual-auditory stimuli with exercise on short-term affect improvement: a randomized controlled trial

Abstrac tPrior research has explored the effects of engaging with real or virtual natural landscapes and listening to music during aerobic exercise on short-term affect, however, the specific differences in the improvement of short-term affect by different combinations of Virtual Reality (VR) and music rhythm require further investigation. The objective of this study is to investigate the effects of various combinations of VR and music on short-term mood, thereby providing a reference for future research on public fitness. This study recruited 132 valid participants (mean age 24.0 ± 0.9 years), with a gender distribution of 68 males and 64 females. Participants were randomly assigned to one of four groups: Visual-Music (V-M), Music-Visual (M-V), Visual-only (V), and Music-only (M). The exercise mode was 15 min of aerobic power cycling with 2 min of low-intensity power cycling intervals in the middle. After the exercise, the participants were asked to sit and then performed either a VR intervention or a music intervention for 15 min. The collected indicators included blood pressure, positive/negative affect, and heart rate variability indicators (RMSSD, SDNN, LF/HF). Data analysis included descriptive statistics, repeated measures ANOVA, and multifactor ANOVA. The effect of different VR and Music combined with exercise interventions on the improvement of short-term affect was analyzed based on the effect size (ɳp2) and combined with the significance p-value. Intra-group results showed that DBP, positive and negative affect, SDNN, RMSSD indicators in V-M group were significant differences (p < 0.05), while SBP, positive affect, negative affect, SDNN, RMSSD, LF/HF indicators in M-V group were significant differences (p < 0.05). Only SDNN and RMSSD indicators in M group had significant differences (p < 0.05), and only SBP and RMSSD indicators in V group had significant differences (p < 0.05). The results between groups showed that only SDNN and LH/HF groups had a significant difference (p < 0.05), other indicators had a trend of improvement or positive promotion to a certain extent, but the statistical difference was not significant (p > 0.05). Aerobic exercise with consistent intensity and the combined visual-auditory interventions (M-V and V-M) significantly improved blood pressure, and the short-term affect of physiological responses (LF/HF, SDNN, RMSSD), along with subjective affect measures, compared to other groups. These findings suggest that incorporating VR and music with exercise can effectively enhance short-term affect, recommending an integrated approach to aerobic exercise and relaxation through music and visual exposure to natural environments.

Exploring immediate cardiorespiratory responses: low-intensity blood flow restricted cycling vs. moderate-intensity traditional exercise in a randomized crossover trial

PurposeBlood-flow restriction (BFR) endurance training may increase endurance performance and muscle strength similar to traditional endurance training while requiring a lower training intensity. We aimed to compare acute cardiorespiratory responses to low-intensity interval exercise under BFR with moderate-intensity traditional interval exercise (TRA).MethodsWe conducted a randomized crossover study. The protocol involved three cycling intervals interspersed with 1 min resting periods. With a 48-h washout period, individuals performed the protocol twice in random order: once as BFR-50 (i.e., 50% incremental peak power output [IPPO] and 50% limb occlusion pressure [LOP]) and once as TRA-65 (65% IPPO without occlusion). TRA-65 intervals lasted 2 min, and time-matched BFR-50 lasted 2 min and 18 s. Respiratory parameters were collected by breath-by-breath analysis. The ratings of perceived breathing and leg exertion (RPE, 0 to 10) were assessed. Linear mixed models were used for analysis.ResultsOut of the 28 participants initially enrolled in the study, 24 healthy individuals (18 males and 6 females) completed both measurements. Compared with TRA-65, BFR-50 elicited lower minute ventilation (VE, primary outcome) (-3.1 l/min [-4.4 to -1.7]), oxygen consumption (-0.22 l/min [-0.28 to -0.16]), carbon dioxide production (-0.25 l/min [-0.29 to -0.20]) and RPE breathing (-0.9 [-1.2 to -0.6]). RPE leg was significantly greater in the BFR-50 group (1.3 [1.0 to 1.7]).ConclusionBFR endurance exercise at 50% IPPO and 50% LOP resulted in lower cardiorespiratory work and perceived breathing effort compared to TRA at 65% IPPO. BFR-50 could be an attractive alternative for TRA-65, eliciting less respiratory work and perceived breathing effort while augmenting perceived leg muscle effort.Trial registrationNCT05163600; December 20, 2021.

An Aerobic Cooldown After Morning, Fasted Resistance Exercise Has Limited Impact on Post-exercise Hyperglycemia in Adults With Type 1 Diabetes: A Randomized Crossover Study

ObjectivesExpert guidelines recommend an aerobic cooldown to lower blood glucose for the management of post-exercise hyperglycemia. This strategy has never been empirically tested. Our aim in this study was to compare the glycemic effects of performing an aerobic cooldown vs not performing a cooldown after a fasted resistance exercise session. We hypothesized that the cooldown would lower blood glucose in the 30 minutes after exercise and would result in less time in hyperglycemia in the 6 hours after exercise. MethodsParticipants completed 2 identical resistance exercise sessions. One was followed by a low-intensity (30% of peak oxygen consumption) 10-minute cycle ergometer cooldown, and the other was followed by 10 minutes of sitting. We compared the changes in capillary glucose concentration during these sessions and continuous glucose monitoring (CGM) outcomes over 24 hours post-exercise. ResultsSixteen participants completed the trial. Capillary glucose was similar between conditions at the start of exercise (p=0.07). Capillary glucose concentration decreased by 0.6±1.0 mmol/L during the 10-minute cooldown, but it increased by 0.7±1.3 mmol/L during the same time in the no-cooldown condition. The resulting difference in glucose trajectory led to a significant interaction (p=0.02), with no effect from treatment (p=0.7). Capillary glucose values at the end of recovery were similar between conditions (p>0.05). There were no significant differences in CGM outcomes. ConclusionsAn aerobic cooldown reduces glucose concentration in the post-exercise period, but the small and brief nature of this reduction makes this strategy unlikely to be an effective treatment for hyperglycemia occurring after fasted exercise.

The difference of affect improvement effect of music intervention in aerobic exercise at different time periods.

Objectives: A randomized controlled experimental design that combines exercise and music intervention was adopted in this study to verify whether this approach could help improve human affect. The differences in the effect of music listening on affective improvement were compared in four different periods: before, during, and after aerobic power cycling exercise and the whole exercise course. Method: A total of 140 subjects aged 19-30 years (average age: 23.6 years) were recruited and randomly divided into four music intervention groups, namely, the pre-exercise, during-exercise, post-exercise, and the whole-course groups. The subjects' demographic and sociological variables and daily physical activities were collected using questionnaires. Individual factors, such as the subjects' noise sensitivity, personality traits, and degree of learning burnout, were collected via scale scoring. A laboratory in Zhejiang Normal University was selected as the experimental site. The testing procedure can be summarized as follows. In a quiet environment, the subjects were asked to sit quietly for 5min after completing a preparation work, and then they were informed to take a pre-test. The four subject groups wore headphones and completed 20min of aerobic cycling (i.e., 7min of moderate-intensity cycling [50%*HRR + RHR] + 6min of low-intensity interval cycling [30%*HRR + RHR] + 7min of moderate-intensity cycling [50%*HRR + RHR] after returning to a calm state (no less than 20min) for post-testing. The affect improvement indicators (dependent variables) collected in the field included blood pressure (BP), positive/negative affect, and heart rate variability indicators (RMSSD, SDNN, and LF/HF). Results: 1) Significant differences were found in the participants' systolic BP (SBP) indices and the effect of improvement of the positive affect during the exercise-music intervention among the four groups at different durations for the same exercise intensity (F = 2.379, p = 0.030, ɳp 2 = 0.058; F = 2.451, p = 0.043, ɳp 2 = 0.091). 2) Music intervention for individuals during exercise contribute more to the reduction of SBP than the other three time periods (F = 3.170, p = 0.047, ɳp 2 = 0.068). Improvement in the participants' negativity affective score was also better during exercise, and it was significantly different than the other three time periods (F = 5.516, p = 0.006, ɳp 2 = 0.113). No significant differences were found in the improvement effects of the other effective indicators for the four periods. Conclusion: Exercise combined with music intervention has a facilitative effect on human affect improvement, and listening to music during exercise has a better impact on affective improvement than music interventions at the other periods. When people perform physical activities, listening to music during exercise positively affects the progress effect among them.

Effect of low-intensity aerobic cycling ergometer on disease severity and depression of patients with myasthenia gravis in “Dr. Soetomo” General Hospital, Surabaya

Background and objectives. Myasthenia gravis (MG) is a chronic autoimmune disease characterized by muscle weakness. Muscle weakness leads to impairment of daily activities and leads to psychiatric symptoms, including depression. The lack of exercise methods in MG patients is a problem in rehabilitation. This study evaluates the effect of an 8-week low-intensity aerobic exercise program on Myasthenia Gravis Composite (MGC) and Beck Depression Inventory (BDI) scores in MG patients. Materials and methods. This is a randomized controlled trial conducted from May to June 2023. Twenty subjects were randomly divided into treatment group and control group. The treatment group received low-intensity aerobic exercise with cycle ergometer 3 sessions per week for 8 weeks. Both groups were informed about lifestyle changes and effective breathing exercises. MGC and BDI scores were measured and compared before and after intervention. Results. In the treatment group, MGC and BDI scores was significantly decreased with strong effect size after 8 weeks (5.4 ± 2.32 to 2.4 ± 1.84, p = 0.001, Cohen’s D = 1.57; and 10.4 ± 2.88 to 5.9 ± 2.77, p = 0.001, Cohen’s D = 1.86). In the control group, MGC and BDI scores were not significantly different (5.4 ± 2.68 to 6.0 ± 2.49, p = 0.193, Cohen’s D = 0.44; and 10.4 ± 1.71 to 9.6 ± 1.65, p = 0.247, Cohen’s D = 0.39). The MGC score strongly correlated with the BDI score (r = 0.50). Conclusion. 8 weeks of low-intensity aerobic exercise with cycling ergometer reduces disease severity and depression severity in myasthenia gravis.

Sex differences in thermophysiological responses of elderly to low-intensity exercise during uncompensable heat strain

PurposeThe rising frequency of extreme heat events poses an escalating threat of heat-related illnesses and fatalities, placing an additional strain on global healthcare systems. Whether the risk of heat-related issues is sex specific, particularly among the elderly, remains uncertain.Methods16 men and 15 women of similar age (69 ± 5 years) were exposed to an air temperature of 39.1 ± 0.3 °C and a relative humidity (RH) of 25.1 ± 1.9%, during 20 min of seated rest and at least 40 min of low-intensity (10 W) cycling exercise. RH was gradually increased by 2% every 5 min starting at minute 30. We measured sweat rate, heart rate, thermal sensation, and the rise in gastrointestinal temperature (Tgi) and skin temperature (Tsk).ResultsTgi consistently increased from minute 30 to 60, with no significant difference between females and males (0.012 ± 0.004 °C/min vs. 0.011 ± 0.005 °C/min; p = 0.64). Similarly, Tsk increase did not differ between females and males (0.044 ± 0.007 °C/min vs. 0.038 ± 0.011 °C/min; p = 0.07). Females exhibited lower sweat rates than males (0.29 ± 0.06 vs. 0.45 ± 0.14 mg/m2/min; p < 0.001) in particular at relative humidities exceeding 30%. No sex differences in heart rate and thermal sensation were observed.ConclusionElderly females exhibit significantly lower sweat rates than their male counterparts during low-intensity exercise at ambient temperatures of 39 °C when humidity exceeds 30%. However, both elderly males and females demonstrate a comparable rise in core temperature, skin temperature, and mean body temperature, indicating similar health-related risks associated with heat exposure.

Active ischemic pre-conditioning does not additively improve short-term high-intensity cycling performance when combined with caffeine ingestion in trained young men.

We investigated the effect of ischemic preconditioning (IPC) with and without caffeine supplementation on mean power output (MPO) during a 4-min cycling time-trial (TT). In a double-blinded, randomized, crossover-design, 11 trained men performed a TT on 4days separated by ∼1week. One hour before TT, participants ingested either caffeine (3mgkgbw-1) or placebo pills, after which femoral blood-flow was either restricted with occlusion cuffs inflated to ∼180mmHg (IPC), or sham-restricted (0-10mmHg; Sham) during 3×2-min low-intensity cycling (10% of incremental peak power output). Then, participants performed a standardized warm-up followed by the TT. Plasma lactate and K+ concentrations and ratings of perceived exertion (RPE) were measured throughout trials. TT MPO was 382±17W in Placebo+Sham and not different from Placebo+IPC (-1W; 95% CI: -9 to 7; p=0.848; d: 0.06), whereas MPO was higher with Caffeine+Sham (+6W; 95% CI: -2 to 14; p=0.115; d: 0.49) and Caffeine+IPC (+8W; 95% CI: 2-13; p=0.019; d: 0.79) versus Placebo+Sham. MPO differences were attributed to caffeine (caffeine main-effect: +7W; 95% CI: 2-13; p=0.015; d: 0.54. IPC main-effect: 0W; 95% CI: -6 to 7; p=0.891; d: 0.03; caffeine×IPC interaction-effect: p=0.580; d: 0.17). TT RPE and plasma variables were not different between treatments. In conlcusion, IPC with co-ingestion of placebo does not improve short-term high-intensity performance in trained men versus a double-placebo control (Placebo+Sham) and does not additively enhance performance with caffeine. These data do not support IPC as a useful strategy for athletes prior to competition but confirms caffeine's performance-enhancing effect.

Exploring the direct and indirect effects of cardiovascular disease risk factors on exercise blood pressure.

Exaggerated exercise blood pressure (BP) is independently associated with cardiovascular disease (CVD) outcomes. However, it is unknown how individual CVD risk factors may interact with one another to influence exercise BP. The aim of this study was to quantify direct and indirect associations between CVD risk factors and exercise BP, to determine what CVD risk factor/s most-strongly relate to exercise BP. In a cross-sectional design, 660 participants (44 ± 2.6 years, 54% male) from the population-based Childhood Determinants of Adult Health Study had BP measured during low-intensity fixed-workload cycling. CVD risk factors were measured, including body composition, clinic (rest) BP, blood biomarkers, and cardiorespiratory fitness. Associations between CVD risk factors and exercise BP were assessed using linear regression, with direct and indirect pathways of association assessed via structural equation model. Sex, waist-to-hip ratio, fitness, and clinic BP were independently associated with exercise systolic BP (SBP), and along with age, had direct associations with exercise SBP (p < 0.05 all). Most CVD risk factors were indirectly associated with exercise SBP via a relation with clinic BP (p < 0.05 all). Clinic BP, waist-to-hip ratio, and fitness were most-strongly associated (direct and indirect association) with exercise SBP (β[95% CI]: 9.35 [8.04, 10.67], 4.91 [2.56, 7.26], and -2.88 [-4.25, -1.51] mm Hg/SD, respectively). Many CVD risk factors are associated with exercise BP, mostly with indirect effects via clinic BP. Clinic BP, body composition, and fitness were most-strongly associated with exercise BP. These results may elucidate how lifestyle modification could be a primary strategy to decrease exaggerated exercise BP-related CVD risk.

Impact of 14 Days of Bed Rest in Older Adults and an Exercise Countermeasure on Body Composition, Muscle Strength, and Cardiovascular Function: Canadian Space Agency Standard Measures

Introduction: Head-down bed rest (HDBR) has long been used as an analog to microgravity, and it also enables studying the changes occurring with aging. Exercise is the most effective countermeasure for the deleterious effects of inactivity. The aim of this study was to investigate the efficacy of an exercise countermeasure in healthy older participants on attenuating musculoskeletal deconditioning, cardiovascular fitness level, and muscle strength during 14 days of HDBR as part of the standard measures of the Canadian Space Agency. Methods: Twenty-three participants (12 males and 11 females), aged 55–65 years, were admitted for a 26-day inpatient stay at the McGill University Health Centre. After 5 days of baseline assessment tests, they underwent 14 days of continuous HDBR followed by 7 days of recovery with repeated tests. Participants were randomized to passive physiotherapy or an exercise countermeasure during the HDBR period consisting of 3 sessions per day of either high-intensity interval training (HIIT) or low-intensity cycling or strength exercises for the lower and upper body. Peak aerobic power (V̇O2peak) was determined using indirect calorimetry. Body composition was assessed by dual-energy X-ray absorptiometry, and several muscle group strengths were evaluated using an adjustable chair dynamometer. A vertical jump was used to assess whole-body power output, and a tilt test was used to measure cardiovascular and orthostatic challenges. Additionally, changes in various blood parameters were measured as well as the effects of exercise countermeasure on these measurements. Results: There were no differences at baseline in main characteristics between the control and exercise groups. The exercise group maintained V̇O2peak levels similar to baseline, whereas it decreased in the control group following 14 days of HDBR. Body weight significantly decreased in both groups. Total and leg lean masses decreased in both groups. However, total body fat mass decreased only in the exercise group. Isometric and isokinetic knee extension muscle strength were significantly reduced in both groups. Peak velocity, flight height, and flight time were significantly reduced in both groups with HDBR. Conclusion: In this first Canadian HDBR study in older adults, an exercise countermeasure helped maintain aerobic fitness and lean body mass without affecting the reduction of knee extension strength. However, it was ineffective in protecting against orthostatic intolerance. These results support HIIT as a promising approach to preserve astronaut health and functioning during space missions, and to prevent deconditioning as a result of hospitalization in older adults.

Sex Difference In Muscle Sympathetic Nerve Activity During Low-intensity Leg Cycling

Sex Difference In Muscle Sympathetic Nerve Activity During Low-intensity Leg Cycling

Effects of Low-Intensity Aerobic Exercise on Neurophysiological and Behavioral Correlates of Cognitive Function.

Acute aerobic exercise exerts a small beneficial effect on cognition. Previous research primarily examines cognitive changes following a bout of exercise, while little is currently known about changes in cognitive performance during exercise. The primary purpose of this study was to examine the effects of low-intensity cycling on cognitive function indexed by behavioral (response accuracy; reaction time) and neurocognitive (P3 mean amplitude; P3 centroid latency) responses. Twenty-seven (Mage = 22.9 ± 3.0 years old) individuals were counterbalanced into low-intensity exercise (EX) and seated control (SC) conditions spread across two testing sessions. During each condition, participants completed a 10 min resting baseline period, 20 min of either sustained cycling or seated rest, and a 20 min recovery period. Primary outcomes were assessed at 10 min intervals (five blocks total) throughout each condition via a modified visual oddball task while electroencephalography (EEG) responses were measured. Across time blocks, both conditions exhibited faster reaction times on frequent trials but reduced accuracy to rare trials, suggesting a speed-accuracy tradeoff. There were no differences between conditions in P3 centroid latency, whereas a significant reduction in P3 amplitude was observed during the 20 min exercise period compared to the control condition. Taken together, results suggest that exercise at lower doses may have minimal influence on behavioral outcomes of cognitive performance but may impact more basic measures of brain function. Information gathered from this study may aid in the development of appropriate exercise prescriptions for populations looking to specifically target cognitive function deficits.

Restricted nasal-only breathing during self-selected low intensity training does not affect training intensity distribution.

Introduction: Low-intensity endurance training is frequently performed at gradually higher training intensities than intended, resulting in a shift towards threshold training. By restricting oral breathing and only allowing for nasal breathing this shift might be reduced. Methods: Nineteen physically healthy adults (3 females, age: 26.5 ± 5.1years; height: 1.77 ± 0.08m; body mass: 77.3 ± 11.4kg; VO2peak: 53.4 ± 6.6mL·kg-1min-1) performed 60min of self-selected, similar (144.7 ± 56.3 vs. 147.0 ± 54.2 W, p = 0.60) low-intensity cycling with breathing restriction (nasal-only breathing) and without restrictions (oro-nasal breathing). During these sessions heart rate, respiratory gas exchange data and power output data were recorded continuously. Results: Total ventilation (p < 0.001, ηp 2 = 0.45), carbon dioxide release (p = 0.02, ηp 2 = 0.28), oxygen uptake (p = 0.03, ηp 2 = 0.23), and breathing frequency (p = 0.01, ηp 2 = 0.35) were lower during nasal-only breathing. Furthermore, lower capillary blood lactate concentrations were found towards the end of the training session during nasal-only breathing (time x condition-interaction effect: p = 0.02, ηp 2 = 0.17). Even though discomfort was rated marginally higher during nasal-only breathing (p = 0.03, ηp 2 = 0.24), ratings of perceived effort did not differ between the two conditions (p ≥ 0.06, ηp 2 = 0.01). No significant "condition" differences were found for intensity distribution (time spent in training zone quantified by power output and heart rate) (p ≥ 0.24, ηp 2 ≤ 0.07). Conclusion: Nasal-only breathing seems to be associated with possible physiological changes that may help to maintain physical health in endurance athletes during low intensity endurance training. However, it did not prevent participants from performing low-intensity training at higher intensities than intended. Longitudinal studies are warranted to evaluate longitudinal responses of changes in breathing patterns.

Active Heat Acclimation Does Not Alter Muscle-Tendon Unit Properties.

Heat acclimation (HA) is recommended before competing in hot and humid conditions. HA has also been recently suggested to increase muscle strength, but its effects on human's muscle and tendon mechanical properties are not yet fully understood. This study investigated the effect of active HA on gastrocnemius medialis (GM) muscle-tendon properties. Thirty recreationally active participants performed 13 low-intensity cycling sessions, distributed over a 17-d period in hot (HA = ~38°C, ~58% relative humidity; n = 15) or in temperate environment (CON = ~23°C, ~35% relative humidity; n = 15). Mechanical data and high-frame rate ultrasound images were collected during electrically evoked and voluntary contractions pre- and postintervention. Shear modulus was measured at rest in GM, and vertical jump performance was assessed. Core temperature decreased from the first to the last session in HA (-0.4°C ± 0.3°C; P = 0.015), while sweat rate increased (+0.4 ± 0.3 L·h -1 ; P = 0.010), suggesting effective HA, whereas no changes were observed in CON (both P ≥ 0.877). Heart rate was higher in HA versus CON and decreased throughout intervention in groups (both P ≤ 0.008), without an interaction effect ( P = 0.733). Muscle-tendon unit properties (i.e., maximal and explosive isometric torque production, contractile properties, voluntary activation, joint and fascicular force-velocity relationship, passive muscle, and active tendon stiffness) and vertical jump performance did not show training ( P ≥ 0.067) or group-training interaction ( P ≥ 0.232) effects. Effective active HA does not alter muscle-tendon properties. Preparing hot and humid conditions with active HA can be envisaged in all sporting disciplines without the risk of impairing muscle performance.

Blood Flow Restricted Cycling Impairs Subsequent Jumping But Not Balance Performance Slightly More Than Non-Restricted Cycling: An Acute Randomized Controlled Cross-Over Trial.

Chronic blood flow restriction (BFR) training has been shown to improve drop jumping (DJ) and balance performance. However, the acute effects of low intensity BFR cycling on DJ and balance indices have not yet been examined. 28 healthy young adults (9 female; 21.8 ± 2.7years; 1.79 ± 0.08m; 73.9 ± 9.5kg) performed DJ and balance testing before and immediately after 20min low intensity cycling (40% of power at maximal oxygen uptake) with (BFR) and without BFR (noBFR). For DJ related parameters, no significant mode × time interactions were found (p ≥ 0.221, ηp 2 ≤ 0.06). Large time effects for DJ heights and the reactive strength index were observed (p < 0.001, ηp 2 ≥ 0.42). Pairwise comparison revealed notably lower values for both DJ jumping height and reactive strength index at post compared to pre (BFR: -7.4 ± 9.4%, noBFR: -4.2 ± 7.4%). No statistically significant mode × time interactions (p ≥ 0.36; ηp 2 ≤ 0.01) have been observed for balance testing. Low intensity cycling with BFR results in increased (p ≤ 0.01; SMD ≥ 0.72) mean heart rate (+14 ± 8bpm), maximal heart rate (+16 ± 12 bpm), lactate (+0.7 ± 1.2 mmol/L), perceived training intensity (+2.5 ± 1.6au) and pain scores (+4.9 ± 2.2au) compared to noBFR. BFR cycling induced acutely impaired DJ performance, but balance performance was not affected, compared to noBFR cycling. Heart rate, lactate, perceived training intensity, and pain scores were increased during BFR cycling.