High-intensity Interval Exercise Research Articles

Moderate continuous or high intensity interval exercise in heart failure with reduced ejection fraction: Differences between ischemic and non-ischemic etiology

BackgroundExercise for heart failure (HF) with reduced ejection fraction (HFrEF) is recommended by guidelines, but exercise mode and intensities are not differentiated between HF etiologies. We, therefore, investigated the effect of moderate or high intensity exercise on left ventricular end-diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF) and maximal exercise capacity (peak VO2) in patients with ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM). MethodsThe Study of Myocardial Recovery after Exercise Training in Heart Failure (SMARTEX-HF) consecutively enrolled 231 patients with HFrEF (LVEF ≤ 35 %, NYHA II-III) in a 12-weeks supervised exercise program. Patients were stratified for HFrEF etiology (ICM versus NICM) and randomly assigned (1:1:1) to supervised exercise thrice weekly: a) moderate continuous training (MCT) at 60–70 % of peak heart rate (HR), b) high intensity interval training (HIIIT) at 90–95 % peak HR, or c) recommendation of regular exercise (RRE) according to guidelines. LVEDD, LVEF and peak VO2 were assessed at baseline, after 12 and 52 weeks. Results215 patients completed the intervention. ICM (59 %; n = 126) compared to NICM patients (41 %; n = 89) had significantly lower peak VO2 values at baseline and after 12 weeks (difference in peak VO2 2.2 mL/(kg*min); p < 0.0005) without differences between time points (p = 0.11) or training groups (p = 0.15). Etiology did not influence changes of LVEDD or LVEF (p = 0.30; p = 0.12), even when adjusting for sex, age and smoking status (p = 0.54; p = 0.12). Similar findings were observed after 52 weeks. ConclusionsEtiology of HFrEF did not influence the effects of moderate or high intensity exercise on cardiac dimensions, systolic function or exercise capacity. Clinical Trial Registration–URLhttp://www.clinicaltrials.gov. Unique identifier: NCT00917046.

The effect of one bout high intensity interval exercise (HIIE) on serum levels of decorin and IGF-I in active young men

The effect of one bout high intensity interval exercise (HIIE) on serum levels of decorin and IGF-I in active young men

Higher Oxygen Uptake And Heart Rate Response In Recovery From Acute High Intensity Interval Exercise

Optimizing energy expenditure is paramount to achieving negative energy balance and promoting weight loss. High intensity interval exercise (HIIE) has been popularized for its ability to reduce body fat despite its time efficiency, yet it is unknown if the majority of calories burned during acute HIIE stems from completion of each interval or subsequent recovery period. Moreover, it is thought that the adaptive response to HIIE is mediated by the acute metabolic stress, but it is unknown if this stems from the interval or recovery phase of training. PURPOSE: To compare oxygen uptake (VO2) and heart values (HR) acquired during HIIE and in subsequent recovery to various HIIE regimens. METHODS: Data from 6 previously-published studies requiring various cycling-based HIIE regimens were analyzed from 89 healthy and active men and women (age, BMI, PPO, and VO2max = 25 ± 6 yr, 24 ± 3 kg/m2, 276 ± 59 W, and 40 ± 7 mL/kg/min). HIIE protocols included six to twelve 30 s - 2.5 min efforts at intensities ranging from 70 - 85 %PPO, with recovery periods ranging from 30 - 75 s. During exercise, VO2, HR, and blood lactate concentration (BLa) were acquired. RESULTS: HIIE bouts elicited peak HR, VO2, and BLa equal to 90 ± 6 %HRmax, 76 ± 12 %VO2max, and 10 ± 4 mM, respectively, and calorie expenditure was equal to 173 ± 47 kcal. Paired t-test revealed significantly higher VO2 (1.95 ± 0.46 L/min vs. 2.02 ± 0.46 L/min, p < 0.001) and HR (158 ± 14 b/min vs. 161 ± 15 b/min, p < 0.001) during recovery from acute HIIE versus the intervals. Significant inverse associations were demonstrated between VO2max and peak VO2 (r = -0.40, p < 0.001) and peak HR (r = -0.30, p = 0.004) attained during HIIE. CONCLUSIONS: Data reveal a significantly higher VO2 during recovery from HIIE compared to each interval, which may be due to slow O2 kinetics of these average fitness adults. HR was also higher in recovery suggesting a severe stress on the cardiovascular system not only during each interval, but also in recovery despite the low power outputs completed. More fit participants showed a blunted VO2 and HR response to HIIE suggesting that they may be at lower relative intensities versus less fit individuals. The structure of recovery periods as well as the interval efforts may be modified by clinicians to optimize calorie expenditure and metabolic stress of acute HIIE.

Enjoyment And Tolerance Of Exercise Intensity In Objectively Versus Subjectively Regulated Interval Exercise In Older Adults

High-intensity interval exercise (HIIE) has led to significant improvements in fitness in healthy and clinical populations, including older adults. Recent evidence suggests that treadmill based HIIE using subjectively regulated HIIE may be more practically applicable to the real world and generates a similar training load for older adults to heart rate regulated HIIE. According to the guidelines of the American College of Sports Medicine, information regarding exercise enjoyment and individual preference for and tolerance of exercise intensity should be considered when developing and modifying exercise prescriptions for successful exercise adherence. PURPOSE: To examine the associations of preference for and tolerance of exercise intensity with physiological performance and perceptual outcomes during single sessions of HIIE using either subjectively (SUB) or objectively (OBJ) prescribed exercise in a treadmill in apparently healthy older adults. METHODS: Fourteen participants (71 ± 9 yrs) completed the Physical Activity Enjoyment Scale to measure exercise enjoyment and Preference for and Tolerance of the Intensity of Exercise Questionnaire to measure Preference (PREF) and Tolerance (TOL). Participants underwent an incremental exercise test on a treadmill in order to prescribe the OBJ session. This was followed by two randomly assigned HIIE sessions wherein the intensity of the exercise was prescribed and regulated by either heart rate (OBJ) or ratings of perceived exertion (RPE; SUB). The HIIE bouts consisted of 10 cycles of 1-min intervals at 80-90% and 30-40% HRpeak and at 8-9 and 3-4 RPE values for the OBJ and SUB sessions, respectively. Oxygen consumption (VO2), speed, and incline were measured during the OBJ and SUB sessions. RESULTS: Enjoyment was positively associated with speed during the OBJ (r = .60, p = .02) and SUB (r = .84, p < .01) sessions, incline during the OBJ (r = .60, p.03) session, and VO2 during the SUB (r = .73, p < .01) session. PREF was not significantly associated with any of the outcomes. TOL was negatively associated with incline during the SUB session (r = -.51, p = .05). CONCLUSIONS: Enjoyment and TOL scores, through associations with speed and VO2 in subjectively-regulated HIIT sessions, may be important for personalizing and modifying exercise prescriptions in older adults.

Work Rate Adjustments, Cardiovascular Strain, And Thermal Strain During High-intensity Interval Exercise In The Heat

Work Rate Adjustments, Cardiovascular Strain, And Thermal Strain During High-intensity Interval Exercise In The Heat

Effects Of Different Exercise Modes On The Bbb Leptin Filtration Rate In High-fat Diet Rats

PURPOSE:Obese people have a higher level of leptin, but due to the impaired transmission of leptin in the blood-brain barrier (BBB), the body's sensitivity to leptin is reduced, so that leptin can not fully play its biological function. Exercise is an effective intervention, but the mechanism of its effect on leptin unclear. Therefore, we investigated the effects of aerobic exercise and high-intensity interval exercise (HIIT) on the leptin filtration rate in BBB in high-fat diet rats, providing experimental evidence for the possible mechanism of exercise regulating energy metabolism. METHODS:36 4-week-old male SD rats were divided into 4 groups, namely control group (C), high-fat diet group (H), high-fat diet aerobic exercise group (HE), high-fat diet HIIT group (HH). HE exercised at 65%VO2max continuously, and HH exercised at 50% VO2max and 90% VO2max alternately every 3 minutes for 8 times in total. Both exercise groups exercised 60 minutes, 5 days a week for 8 weeks. VO2max was measured every two weeks. After 8 weeks of intervention, cerebrospinal fluid was extracted from the foramen magnum, and blood was taken from abdominal aorta to measure leptin content, hypothalamus was taken to measure Proopiomelancortin (POMC) and neuropeptide Y (NPY) protein expression. RESULTS:(1) compared with C, BBB leptin filtration rate and POMC expression in H were decreased (P < 0.05), NPY expression, food intake, body weight and body fat percentage were significantly increased (P < 0.05); (2) compared with H, BBB leptin filtration rate and POMC expression were increased in HE and HH (P < 0.05), NPY expression, food intake, body weight and body fat percentage were decreased significantly (P < 0.05); (3) compared with HH, BBB leptin filtration rate were increased significantly in HE, however, there was no significant difference in other indicators. CONCLUSIONS:8-week exercise intervention can achieve the goal of reducing fat and weight by inhibiting the body's energy intake, and the intervention effect of aerobic exercise is better than that of HIIT exercise, the mechanism is related to the changes of BBB leptin filtration rate and downstream proteins related to appetite regulation.

Acute Effects Of Different Exercise Modes On Salivary Iga And Plasma Cortisol Secretory Responses

Salivary Immunoglobulin A (IgA) prevent bacterial attachment to the mucosal surfaces. High-intensity or long-term exercise causes a transient decrease in oral immune function through decreased salivary IgA secretion, and this response is associated with exercise-induced stress, such as cortisol. However, it is unclear whether differences in exercise modes affect salivary IgA and plasma cortisol secretory responses. PURPOSE:The purpose of this study was to examine whether differences in exercise modes affect salivary IgA and plasma cortisol secretory responses to a single bout of exercise. METHODS:Seven healthy young males with no exercise habits participated in the study. Subjects randomly performed two conditions: moderate-intensity continuous exercise (MICE) for 20 min cycle exercise at a work rate equivalent to 70% VO2max, and high-intensity interval exercise (HIIE, same total exercising volume to MICE) for 20 min cycle exercise, consisting of five 2 min bouts at 90% VO2max with 2 min active recovery at 50% VO2max. Saliva and blood samples were collected before, immediately after, 30 min after each exercise condition. The salivary IgA secretion rate was calculated from salivary IgA concentration and saliva volume per minute. RESULTS:In MICE, change in salivary IgA secretion rate at immediately after and 30 min after exercise was significantly lower than that before exercise (P < 0.05), but did not change in HIIE. In addition, the amount of change (area under the curve) in salivary IgA secretion rate in MICE was lower than that in HIIE (P < 0.05). Plasma cortisol concentration did not change in both MICE and HIIE. However, there was a significant negative correlation between salivary IgA secretion rate and plasma cortisol concentration in MICE (r = -0.544, P < 0.05). CONCLUSIONS:These results suggest that the salivary IgA secretory response may differ with different exercise modes. In MICE, the reduced salivary IgA secretory response may be associated with the increase in systemic cortisol concentration. Supported by Grants-in-Aid for Scientific Research (#19 K22828, M. Iemitsu)

Cerebrovascular Regulation In Response To High-intensity Interval Exercise

Cerebrovascular Regulation In Response To High-intensity Interval Exercise

Cardiometabolic Disease Risk in Normal Weight Obesity and Exercise Interventions for Proactive Prevention

PURPOSE: Normal weight obesity (NWO) is characterized by a normal body mass index but a high body fat mass percentage and low skeletal muscle mass, thereby increasing the risk of cardiometabolic dysfunction and morbidity. However, the effects of exercise intervention in reducing the risk of cardiometabolic disease in NWO have not been fully elucidated. Therefore, this review aimed to summarize the potential cardiometabolic disease risk and to provide implications of exercise interventions for the proactive prevention of cardiometabolic disease risk in NWO.METHODS: We searched and summarized the literature on the cardiometabolic risk factors in NWO. In addition, we summarized literature investigating the effects of exercise intervention on the cardiometabolic risk factors in NWO. We performed the literature search using PubMed, Web of Science, and Google Scholar databases.RESULTS: NWO was associated with increased visceral fat, ectopic fat, oxidative stress, inflammatory cytokines, insulin resistance, dyslipidemia, and subclinical atherosclerosis compared with normal weight lean. NWO requires exercise interventions that induce alterations in body composition, such as decreased body fat percentage and increased muscle mass. Resistance exercise (RE) and high-intensity interval exercise (HIIE) can improve lipid components and alter body composition in NWO. In addition, low-intensity blood flow restriction resistance exercise (BFR-RE) may enhance muscular strength and anaerobic power in NWO.CONCLUSIONS: The cardiometabolic disease risk is increased in NWO. We suggest that exercise interventions (RE, HIIE, and BFR-RE) may effectively prevent cardiometabolic disease risk and alter body composition in NWO. As this has potential implications for exercise interventions in NWO, further investigations are needed to find the optimal exercise for proactive prevention of cardiometabolic risk in NWO.

The Role of Fitness Status and Sex on Metabolic Flexibility during a Bout of High-Intensity Interval Exercise and a High-Fat Meal Challenge

We explored whether High-Intensity Interval Exercise (HIIE) could provide a novel method to test metabolic flexibility during exercise. We also aimed to assess substrate oxidation during HIIE and in response to a high-fat meal to determine if these assessments of metabolic flexibility are influenced by fitness and sex.

Acute high-intensity interval exercise is less pro-oxidative/thrombotic compared to isovolumic moderate-intensity steady-state exercise.

While high-intensity interval training (HIIT) has emerged as a more time-efficient alternative to moderate-intensity steady-state exercise (MISS), the impact on systemic free radical formation and link to activated coagulation remains unknown. We recruited sixteen healthy males aged 21 ± 3 y who performed incremental cycle ergometry to determine peak oxygen uptake ([Formula: see text] PEAK). Participants were randomly assigned single blind to two separate groups (MISS: n = 8; HIIT: n = 8) matched for [Formula: see text] PEAK. HIIT participants completed five exercise cycles, each consisting of 3min at 80%[Formula: see text] PEAK alternating with 3min at 40% [Formula: see text] PEAK, whereas MISS participants performed an isovolumic bout of 30min at 60% [Formula: see text] PEAK. Cephalic venous blood was assayed for ascorbate free radical (A•-, electron paramagnetic resonance spectroscopy) and clot fractal dimension (df, rheometry) at rest every hour over a 6-h period to determine critical difference (CD) and before/after submaximal/peak exercise. Submaximal MISS increased A• - and df to a greater extent compared to HIIT (P = 0.039 to 0.057) although elevations generally fell within CD boundaries (54.2% and 5.5% respectively). No further elevations were observed during peak exercise (P = 0.508 to 0.827) and no relationships were observed between A•- and df (r = 0.435 to - 0.121, P = 0.092 to 0.655). Collectively, these findings suggest that HIIT is less pro-oxidative/thrombotic compared to more traditional MISS, advocating its prescription in patients given the potential for superior vascular adaptive benefit.

Interleukin-6, undercarboxylated osteocalcin, and brain-derived neurotrophic factor responses to single and repeated sessions of high-intensity interval exercise

ObjectivesThe purpose of this study was to compare the effects of a single session of high-intensity interval exercise (HIIE) with 2 consecutive HIIEs, separated by 3 h of recovery, on plasma interleukin-6 (IL-6), undercarboxylated osteocalcin (ucOC), and brain-derived neurotrophic factor (BDNF) responses. MethodsTwenty male recreational endurance athletes completed two HIIE trials in a randomized crossover design: a single session of HIIE on the single exercise day (HIIE-S) and two sessions of HIIE 3 h apart on the double exercise day (HIIE-D). The HIIE protocol consisted of 10 × 1 min cycling at 100 % of peak oxygen uptake, with 75 s of low-intensity cycling at 60 W. Blood samples were collected to analyze IL-6, ucOC, and BDNF levels before and immediately after HIIE on the HIIE-S and before and immediately after the second HIIE on the HIIE-D. ResultsBoth HIIE interventions significantly increased (p < 0.001) plasma IL-6 (HIIE-S 33.90 % vs HIIE-D 31.04 %; p = 0.64), ucOC (HIIE-S 37.18 % vs HIIE-D 39.54 %; p = 0.85), and BDNF levels (HIIE-S 236.01 % vs HIIE-D 216.68 %; p = 0.69), with no group effect. ConclusionsOur results demonstrate that performing two consecutive HIIEs on the same day with a 3-h rest results in similar changes in plasma levels of IL-6, BDNF, and ucOC compared with a single session of HIIE.

Effects of Acute High-Intensity Interval Exercise and High-Intensity Continuous Exercise on Inhibitory Function of Overweight and Obese Children.

This study aimed to examine whether a single bout each of high-intensity interval exercise (HIIE) and high-intensity continuous exercise (HICE) could improve inhibitory functions of overweight and obese children, and which mode of exercise was more beneficial. Seventy-two overweight and obese children, with (26.02 ± 1.05 kg/m2), aged 10–14 years (11.56 ± 1.03 years), were randomly assigned to three groups. The HIIE group completed a 30-min treadmill exercise session (5-min warm up, 20-min HIIE, and 5-min cool-down). The HICE group performed 30 min of rope skipping, while the control (CON) group watched a designated cartoon on a tablet computer for the same duration. Reaction time and number of errors in the Stroop test were determined before and after the intervention. The difference between pre- and post-test reaction time scores was higher in the HIIE and HICE groups than in the CON group, while the pre- and post-test difference in the number of errors was similar between groups. Overall, it is likely that both acute HIIE and HICE were similarly efficient in facilitating cognitive and inhibitory functions of children with overweight and obesity conditions, supporting the benefits of acute high-intensity exercise probability for cognitive functions of children in general, as well as of the population with overweight and obesity conditions.

Implementation of exercise countermeasures during spaceflight and microgravity analogue studies: Developing countermeasure protocols for bedrest in older adults (BROA).

Significant progress has been made in the development of countermeasures to attenuate the negative consequences of prolonged exposure to microgravity on astronauts’ bodies. Deconditioning of several organ systems during flight includes losses to cardiorespiratory fitness, muscle mass, bone density and strength. Similar deconditioning also occurs during prolonged bedrest; any protracted time immobile or inactive, especially for unwell older adults (e.g., confined to hospital beds), can lead to similar detrimental health consequences. Due to limitations in physiological research in space, the six-degree head-down tilt bedrest protocol was developed as ground-based analogue to spaceflight. A variety of exercise countermeasures have been tested as interventions to limit detrimental changes and physiological deconditioning of the musculoskeletal and cardiovascular systems. The Canadian Institutes of Health Research and the Canadian Space Agency recently provided funding for research focused on Understanding the Health Impact of Inactivity to study the efficacy of exercise countermeasures in a 14-day randomized clinical trial of six-degree head-down tilt bedrest study in older adults aged 55–65 years old (BROA). Here we will describe the development of a multi-modality countermeasure protocol for the BROA campaign that includes upper- and lower-body resistance exercise and head-down tilt cycle ergometry (high-intensity interval and continuous aerobic exercise training). We provide reasoning for the choice of these modalities following review of the latest available information on exercise as a countermeasure for inactivity and spaceflight-related deconditioning. In summary, this paper sets out to review up-to-date exercise countermeasure research from spaceflight and head-down bedrest studies, whilst providing support for the proposed research countermeasure protocols developed for the bedrest study in older adults.

Telehealth high-intensity interval exercise and cardiometabolic health in spinal cord injury

BackgroundThe number of exercise trials examining cardiometabolic outcomes in spinal cord injury (SCI) is low, and prescribed exercise is often inconvenient for individuals with SCI to perform within their community. Individuals with SCI experience a myriad of barriers to exercise participation, which can include a lack of time, accessible or usable equipment and facilities, and transportation. Thus, it is imperative to identify effective modes of exercise that provide the greatest overall health benefits but do not require a significant time commitment. Low-volume high intensity interval training (HIIT) has demonstrated the same improvements in cardiometabolic health as moderate intensity exercise training (MIT), despite only requiring 20% of the total time commitment in adults without disabilities and more recently in individuals with SCI.ObjectivesThe primary purpose of this study is to integrate a 16 week home-based telehealth HIIT arm crank exercise training program in individuals with SCI and assess changes in cardiometabolic health.MethodsMen and women between the ages of 19 and 60 with a confirmed diagnosis of SCI between C7 and T12 will be recruited for this study. Participants will be randomized to 16 weeks of telehealth HIIT exercise two days per week or a no-exercise control group. Aerobic capacity, muscular strength, blood lipids, glucose tolerance, resting energy expenditure, blood pressure, and body composition will be assessed at baseline and 16 weeks post-training.DiscussionInactivity associated with SCI leads to chronic cardiometabolic health conditions. The majority of exercise interventions to date show that exercise is capable of increasing physical function, aerobic capacity, and muscle mass, and strength. Additionally, we have recently shown the ability of HIIT to improve blood lipid and glucose concentrations. Advances in telehealth exercise approaches have improved the capability to prescribe home-based exercise programs. Therefore, we hypothesize that the utilization of a home-based telehealth HIIT program will improve cardiometabolic health markers, yield high adherence (> 75%), and will be more enjoyable in individuals with SCI.Trial registrationTelehealth High-Intensity Interval Exercise and Cardiometabolic Health in Spinal Cord Injury NCT04940598

Effect of a single bout of high-intensity sprint exercise programme compared to traditional high-intensity sprint interval exercise and endurance exercise on inflammatory markers, lipid profile and health-related physical fitness measurements in participants with elevated cardiovascular disease risk (PhD Academy Award)

Effect of a single bout of high-intensity sprint exercise programme compared to traditional high-intensity sprint interval exercise and endurance exercise on inflammatory markers, lipid profile and health-related physical fitness measurements...

Effects of Acute Exercise on Cognitive Flexibility in Young Adults with Different Levels of Aerobic Fitness.

This study aimed to evaluate the effects of high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) on cognitive flexibility in young adults with differing levels of aerobic fitness. Sixty-six young adults were grouped into high- and low-fit groups based on their final running distance on the 20 m Progressive Aerobic Cardiovascular Endurance Run (PACER) test. Individuals participated in a 10 min HIIE, a 20 min HIIE, a 20 min MICE, and a control session (reading quietly in a chair) in a counterbalanced order. The more-odd shifting task was completed before and approximately 5 min after each intervention to assess cognitive flexibility. The results showed that young adults with a high fitness level gained greater benefits in terms of switch cost from the 20 min HIIE, while low-fitness participants benefited more from the 10 min HIIE and the 20 min MICE. These findings suggest that aerobic fitness may influence the effect of acute HIIE and MICE on cognitive flexibility. Young adults should consider individual fitness level when adopting time-effective and appropriate exercise routines to improve cognitive flexibility.

The Effect of Sleep Restriction, With or Without Exercise, on Skeletal Muscle Transcriptomic Profiles in Healthy Young Males.

BackgroundInadequate sleep is associated with many detrimental health effects, including increased risk of developing insulin resistance and type 2 diabetes. These effects have been associated with changes to the skeletal muscle transcriptome, although this has not been characterised in response to a period of sleep restriction. Exercise induces a beneficial transcriptional response within skeletal muscle that may counteract some of the negative effects associated with sleep restriction. We hypothesised that sleep restriction would down-regulate transcriptional pathways associated with glucose metabolism, but that performing exercise would mitigate these effects.Methods20 healthy young males were allocated to one of three experimental groups: a Normal Sleep (NS) group (8 h time in bed per night (TIB), for five nights (11 pm – 7 am)), a Sleep Restriction (SR) group (4 h TIB, for five nights (3 am – 7 am)), and a Sleep Restriction and Exercise group (SR+EX) (4 h TIB, for five nights (3 am – 7 am) and three high-intensity interval exercise (HIIE) sessions (performed at 10 am)). RNA sequencing was performed on muscle samples collected pre- and post-intervention. Our data was then compared to skeletal muscle transcriptomic data previously reported following sleep deprivation (24 h without sleep).ResultsGene set enrichment analysis (GSEA) indicated there was an increased enrichment of inflammatory and immune response related pathways in the SR group post-intervention. However, in the SR+EX group the direction of enrichment in these same pathways occurred in the opposite directions. Despite this, there were no significant changes at the individual gene level from pre- to post-intervention. A set of genes previously shown to be decreased with sleep deprivation was also decreased in the SR group, but increased in the SR+EX group.ConclusionThe alterations to inflammatory and immune related pathways in skeletal muscle, following five nights of sleep restriction, provide insight regarding the transcriptional changes that underpin the detrimental effects associated with sleep loss. Performing three sessions of HIIE during sleep restriction attenuated some of these transcriptional changes. Overall, the transcriptional alterations observed with a moderate period of sleep restriction were less evident than previously reported changes following a period of sleep deprivation.

The acute effect of exercise intensity on peripheral and cerebral vascular function in healthy adults.

The acute effect of exercise intensity on cerebrovascular reactivity and whether this mirrors changes in peripheral vascular function have not been investigated. The aim of this study was to explore the acute effect of exercise intensity on cerebrovascular reactivity (CVR) and peripheral vascular function in healthy young adults (n = 10, 6 females, 22.7 ± 3.5 yr). Participants completed four experimental conditions on separate days: high-intensity interval exercise (HIIE) with intervals performed at 75% maximal oxygen uptake (V̇o2max; HIIE1), HIIE with intervals performed at 90% V̇o2max (HIIE2), continuous moderate-intensity exercise (MIE) at 60% V̇o2max and a sedentary control condition (CON). All exercise conditions were completed on a cycle ergometer and matched for time (30 min) and average intensity (60% V̇o2max). Brachial artery flow-mediated dilation (FMD) and CVR of the middle cerebral artery were measured before exercise, and 1- and 3-h after exercise. CVR was assessed using transcranial Doppler ultrasonography to both hypercapnia (6% carbon dioxide breathing) and hypocapnia (hyperventilation). FMD was significantly elevated above baseline 1 and 3 h following both HIIE conditions (P < 0.05), but FMD was unchanged following the MIE and CON trials (P > 0.33). CVR to both hypercapnia and hypocapnia, and when expressed across the end-tidal CO2 range, was unchanged in all conditions, at all time points (all P > 0.14). In conclusion, these novel findings show that the acute increases in peripheral vascular function following HIIE, compared with MIE, were not mirrored by changes in cerebrovascular reactivity, which was unaltered following all exercise conditions in healthy young adults.NEW & NOTEWORTHY This is the first study to identify that acute improvements in peripheral vascular function following high-intensity interval exercise are not mirrored by improvements in cerebrovascular reactivity in healthy young adults. High-intensity interval exercise completed at both 75% and 90% V̇o2max increased brachial artery flow-mediated dilation 1 and 3 h following exercise, compared with continuous moderate-intensity exercise and a sedentary control condition. By contrast, cerebrovascular reactivity was unchanged following all four conditions.

Investigating Affective Responses to Remotely Delivered "At Home" Low Volume High Intensity Interval Exercise: A Non-Randomized Parallel Group Feasibility Study.

BackgroundLow volume-high intensity interval exercise (LV-HIIE) has gained interest, due to its efficiency in invoking health and fitness benefits. However, little research has studied “at home” feasibility or effects of LV-HIIE. This study aimed to demonstrate that remote “at-home” LV-HIIE research is possible and to investigate if affective responses to the LV-HIIE protocol, subsequent intentions, and self-efficacy to repeat were related to self-reported tolerance of the intensity of exercise.MethodsUsing self-reported tolerance of the intensity of exercise, 41 healthy, physically active participants (25 female and 16 male; age 21.3 ± 1.0 years, body mass index 23.0 ± 2.9 kg.m2) were divided into low tolerance (LT, n = 14), middle tolerance (MT, n = 15), and high tolerance (HT, n = 12) groups. Participants completed a 20-min LV-HIIE circuit training video [2 × (10 ×30 s work, 15 s rest)] at home. Participants reported ratings of perceived exertion, affective valence, and perceived activation at baseline, during the protocol, immediately post-protocol, and during the cool down. 20-min after completion, respondents answered questions on exercise task self-efficacy and intentions to repeat LV-HIIE.ResultsThe study recruited n = 65 individuals, of whom n = 50 passed screening. Ultimately n = 41 (82%) completed the exercise protocol and data collection. Ratings of perceived exertion were not significantly different between groups (p = 0.56), indicating similar perceptions of task difficulty. There was no significant effect of tolerance on affective valence (p = 0.36) or felt arousal (p = 0.06). There was evidence of high individual variability in affective responses within and between participants. Subsequent intentions and self-efficacy to repeat the exercise protocol did not seem to be related to affective valence during or after the protocol.DiscussionRecruitment and data collection indicated that research into “at home” LV-HIIE is possible. High individual differences in affective responses suggest that LV-HEII may be appropriate for some but not all as an exercise option. Assessing self-reported tolerance of intensity of exercise may not appropriately identify whether or not LV-HIIE will be suitable for an individual.