High-intensity Interval Training in Children With A Chronic Disease Or Condition

Our aim was to investigate the effects and prevalence of nonresponders (NR) to high-intensity interval training (HIIT) and resistance training (RT) in women with insulin resistance on cardiometabolic health parameters. Sedentary overweight/obese insulin-resistant women (age = 33.5 ± 6.5 yr; body mass index = 29.9 ± 3.7 kg/m2) were randomly assigned to a triweekly HIIT program (HIIT; n = 18) or resistance training (RT; n = 17). Anthropometry (body mass, fat mass, muscle mass, waist circumference, and skinfold thickness), cardiovascular (blood pressure), metabolic [fasting glucose, fasting insulin, and homeostatic model of insulin resistance (HOMA-IR)], as well as muscle strength, and endurance performance covariables were measured before and after 12 wk in both intervention groups. The interindividual variability to exercise training of the subjects was categorized as responders and NR using as cut points two times the typical error of measurement in mean outcomes. After intervention, significant reduction in waist circumference, skinfold thicknesses, fat mass, blood pressure, fasting glucose, insulin, and HOMA-IR (P < 0.05) were identified to HIIT and RT group, respectively. Both HIIT and RT groups exhibited a significant decrease in the endurance performance, whereas only RT exhibited increased muscle strength. Significant differences in the NR prevalence between the HIIT and RT groups were identified for a decrease in fat mass (HIIT 33.3% vs. RT 70.5%; P = 0.028), muscle mass (HIIT 100% vs. RT 52.9%; P = 0.001), and tricipital skinfold (HIIT 5.5% vs. RT 29.4%; P < 0.041). For diastolic blood pressure, significant differences were observed in the NR prevalence between the HIIT and RT groups (55.5% vs. 94.1; P = 0.009). However, there were no differences in the NR prevalence between HIIT and RT for decreasing fasting glucose. Twelve weeks of HIIT and RT have similar effects and NR prevalence to improve glucose control variables; however, there is different NR prevalence in other anthropometric, cardiovascular, strength, and endurance performance measurements in insulin-resistant women. These findings were displayed with a similar time investment per week of 114 vs. 108 min, respectively, to HIIT and RT.NEW & NOTEWORTHY The effects and prevalence of nonresponders (NR) to improve glucose control variables have predominately been reported by endurance training. A uniqueness of the present study was to examine the NR prevalence in women with insulin resistance after high-intensity interval (HIIT) and resistance training (RT). This study demonstrates that 12 wk of HIIT and RT have similar effects and NR prevalence to improve glucose control variables. However, significantly different NR prevalence were observed in other anthropometric, cardiovascular, strength, and endurance performance measurements.

High-intensity interval training (HIIT) and sprint interval training (SIT) can improve physiological (eg,maximal oxygen uptake [V˙O2max]) and locomotor (eg,maximal aerobic speed, MAS; maximal sprinting speed, MSS) variables. However, the influence of an athlete's locomotor profile on training adaptations to HIIT and SIT remains unclear. We aimed to (1)compare physiological and locomotor adaptations to HIIT and SIT and (2)assess how locomotor profiles affect these adaptations. Twenty-seven trained male and female runners (27.7 [7.5]y; n = 12 women) completed 6 weeks of HIIT (4-6 × 4min @90%-95% MAS) or SIT (6-10 × 20-s all-out sprints), performed twice weekly. Pretest and posttests included 40-m sprinting (MSS) and incremental treadmill tests (V˙O2max, MAS, lactate thresholds [eg,v4mmo]). Anaerobic speed reserve was calculated as MSS minus MAS and speed reserve ratio as MSS divided by MAS. Linear mixed models and moderation analyses were performed. Both HIIT and SIT significantly improved MAS (P ≤ .03). While only SIT enhanced MSS (interaction: P < .01), HIIT increased v4mmol (P < .01). In both groups, speed types (ie,higher speed reserve ratio and anaerobic speed reserve) showed greater MAS (P < .01) and v4mmol increases (P < .05) than endurance types (ie,lower speed reserve ratio and anaerobic speed reserve). Within the SIT group, endurance types improved MSS (P < .01) and V˙O2max more, while speed types increased V˙O2max more with HIIT (interaction: P ≤ .03). HIIT and SIT improve endurance outcomes in trained runners. Adaptations vary depending on locomotor profile, with speed types responding better to HIIT and endurance types benefiting more from SIT. Accordingly, individualizing training by locomotor profile may optimize outcomes.

This study tested the hypothesis that 6 weeks of high-intensity interval training (HIIT) would induce greater physiological adaptations than moderate-intensity continuous training (MICT) in Thoroughbred horses. Seven untrained horses completed two distance-matched treadmill training protocols (three sessions per week) in a randomized crossover design, separated by a three-month washout: MICT (6 min at 70% ) and HIIT (6 × [30 s at 100% with 30 s at 30% ]). Incremental exercise tests were conducted at weeks 0, 3, and 6 to assess exercise performance and physiological responses. Mixed-effects models were used to analyze the effects of time, protocol, and their interaction (p < 0.05). After 6 weeks, HIIT elicited greater improvements than MICT in run distance to exhaustion (+29% vs. +4.5%), speed at (+9.8% vs. +2.4%), and speed at maximal heart rate (+15% vs. +4.3%). Speed at 10 mmol/L of plasma lactate increased only after HIIT (+13% vs. +6.0%). Both protocols similarly improved (+13%) and maximal cardiac output (+7%-8%). In conclusion, despite being matched for total running distance, HIIT induced superior improvements in performance, cardiovascular function, and lactate kinetics compared with MICT, highlighting training intensity as a key determinant of training adaptations in horses.

Aerobic exercise training can increase brain volume and blood flow, but the impact on brain metabolism is less known. We determined whether high-intensity interval training (HIIT) increases brain metabolism by measuring brain glucose uptake in younger and older adults. Brain glucose uptake was measured before and after HIIT or a sedentary (SED) control period within a larger exercise study. Study procedures were performed at the Mayo Clinic in Rochester, MN. Participants were younger (18 to 30 years) or older (65 to 80 years) SED adults who were free of major medical conditions. Group sizes were 15 for HIIT (nine younger and six older) and 12 for SED (six younger and six older). Participants completed 12 weeks of HIIT or SED. HIIT was 3 days per week of 4 × 4 minute intervals at over 90% of peak aerobic capacity (VO2peak) with 2 days per week of treadmill walking at 70% VO2peak. Resting brain glucose uptake was measured using 18F-fluorodeoxyglucose positron emission tomography scans at baseline and at week 12. Scans were performed at 96 hours after exercise. VO2peak was measured by indirect calorimetry. Glucose uptake increased significantly in the parietal-temporal and caudate regions after HIIT compared with SED. The gains with HIIT were not observed in all brain regions. VO2peak was increased for all participants after HIIT and did not change with SED. We demonstrate that brain glucose metabolism increased after 12 weeks of HIIT in adults in regions where it is reduced in Alzheimer's disease.

BackgroundStudies have shown that high-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) for increasing peak oxygen uptake (VO2peak) and reducing cardiovascular disease (CVD) and mortality. To our knowledge, previously published systematic reviews have neither compared different HIIT models with MICT nor investigated intervention frequencies of HIIT vs. MICT for purposes of improving cardiorespiratory fitness in patients with CVD.ObjectiveThe purpose of this meta-analysis was to compare the effects of different training models, intervention frequencies and weeks of HIIT vs. MICT on changes in cardiorespiratory fitness during cardiac rehabilitation (CR).MethodsA systematic search was carried out for research articles on randomized controlled trials (RCTs) indexed in the PubMed, Cochrane Library, Web of Science, Embase and Scopus databases for the period up to December 2021. We searched for RCTs that compared the effect of HIIT vs. MICT on cardiorespiratory fitness in patients with CVD.ResultsTwenty-two studies with 949 participants (HIIT: 476, MICT: 473) met the inclusion criteria. Sensitivity analysis revealed that HIIT increased VO2peak more than MICT (MD = 1.35). In the training models and durations, there was a greater increase in VO2peak with medium-interval HIIT (MD = 4.02) and more than 12 weeks duration (MD = 2.35) than with MICT. There were significant improvements in VO2peak with a HIIT frequency of 3 times/week (MD = 1.28). Overall, one minor cardiovascular and four non-cardiovascular adverse events were reported in the HIIT group, while six non-cardiovascular adverse events were reported in the MICT group.ConclusionHIIT is safe and appears to be more effective than MICT for improving cardiorespiratory fitness in patients with CVD. Medium-interval HIIT 3 times/week for more than 12 weeks resulted in the largest improvement in cardiorespiratory fitness during CR.Systematic Review Registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021245810, identifier: CRD42021245810.

Background: High-intensity interval training (HIIT) has been shown to improve cardiometabolic health during supervised lab-based studies but adherence, enjoyment, and health benefits of HIIT performed independently are yet to be understood. We compared adherence, enjoyment, and cardiometabolic outcomes after 8 weeks of HIIT or moderate-intensity continuous training (MICT), matched for energy expenditure, in overweight and obese young adults. Methods: 17 adults were randomized to HIIT or MICT. After completing 12 sessions of supervised training over 3 weeks, participants were asked to independently perform HIIT or MICT for 30 min, 4 times/week for 5 weeks. Cardiometabolic outcomes included cardiorespiratory fitness (VO2 peak), lipids, and inflammatory markers. Exercise enjoyment was measured by the validated Physical Activity Enjoyment Scale. Results: Exercise adherence (93.4 ± 3.1% vs. 93.1 ± 3.7%, respectively) and mean enjoyment across the intervention (100.1 ± 4.3 vs. 100.3 ± 4.4, respectively) were high, with no differences between HIIT and MICT (p > .05). Similarly, enjoyment levels did not change over time in either group (p > .05). After training, HIIT exhibited a greater decrease in low-density lipoprotein cholesterol than MICT (−0.66 mmol L−1 vs. −0.03 mmol L−1, respectively) and a greater increase in VO2 peak than MICT (p < .05, +2.6 mL kg min−1 vs. +0.4 mL kg min−1, respectively). Interleukin-6 and C-reactive protein increased in HIIT (+0.5 pg mL−1 and + 31.4 nmol L−1, respectively) and decreased in MICT (−0.6 pg mL−1 and −6.7 nmol L−1, respectively, p < .05). Conclusions: Our novel findings suggest that HIIT is enjoyable and has high unsupervised adherence rates in overweight and obese adults. However, HIIT may be associated with an increase in inflammation with short-term exercise in this population.

Salivary concentrations of IL-8 and IL-1ra after HIIT and MICT in young, healthy adults: A randomized exercise study

The purpose of this study was to examine the effects of a 6 week high-intensity interval training (HIT) program, followed by 2 weeks recovery, on iron status in cyclists. Eleven male collegiate cyclists (21.8 +/- 0.8 yr, 71.4 +/- 2.2 kg, and 8.6 +/- 0.9 % body fat) participated in a 6 week cycle training program that consisted of 5 days of high intensity interval and endurance training per week. Hematocrit (Hct), hemoglobin (Hb), red blood cell (RBC) count, serum iron, serum ferritin, and total iron binding capacity (TIBC) were analyzed from venous blood samples taken at baseline (B), and each week following interval training (T1-T6) and recovery (R1-R2). Dietary intakes including iron were monitored weekly. The dependent variables were analyzed by repeated measures ANOVA (p < 0.05). RBC count, Hb and Hct were significantly decreased compared to baseline at T3. Serum iron did not change significantly. Serum ferritin decreased significantly from 55.9 +/- 9.7 at B to 42.2 +/- 8.0 ng x ml -1 at T5 and remained depressed at T6, R1 and R2. TIBC was significantly increased above baseline at T3, T4, T6, R1 and R2. These results suggest that 6 weeks of high-intensity interval training can reduce iron stores. It is possible that this reduction in iron stores over time could adversely affect aerobic cycling performance.

Background: Recent studies in nondisabled individuals have demonstrated that low-volume high-intensity interval training (HIIT) can improve cardiometabolic health similar to moderate-intensity training (MIT) despite requiring 20% of the overall time commitment. To date, there have been no studies assessing the effects of HIIT for improving cardiometabolic health in individuals with SCI. Objectives: The primary purpose of this pilot study was to compare the effects of 6 weeks of low-volume HIIT vs MIT using arm crank ergometer exercise to improve body composition, cardiovascular fitness, glucose tolerance, blood lipids, and blood pressure in a cohort of individuals with longstanding SCI. Methods: Participants were randomized to 6 weeks of HIIT or MIT arm crank exercise training. Aerobic capacity, muscular strength, blood lipids, glucose tolerance, blood pressure, and body composition were assessed at baseline and 6 weeks post training. Results: Seven individuals (6 male, 1 female; n = 3 in MIT and n = 4 in HIIT; mean age 51.3 ± 10.5 years) with longstanding SCI completed the study. The preliminary findings from this pilot study demonstrated that individuals with SCI randomized to either 6 weeks of HIIT or MIT displayed improvements in (a) insulin sensitivity, (b) cardiovascular fitness, and (c) muscular strength (p < .05). However, MIT led to greater improvements in arm fat percent and chest press strength compared to HIIT (p < .05). Conclusion: No differences between MIT and HIIT were observed. Both conditions led to improvements in insulin sensitivity, aerobic capacity, muscle strength, and blood lipids in individuals with SCI. Future larger cohort studies are needed to determine if the shorter amount of time required from HIIT is preferable to current MIT exercise recommendations.

Background High-intensity interval training (HIIT) has been shown to produce similar improvements in functional capacity and general quality of life (QoL), and a decrease in the Atrial Fibrillation Severity Scale (AFSS) symptom scores of patients with atrial fibrillation (AF), when compared with standard care moderate-to-vigorous intensity continuous training (MICT). However, the long-term effects of exercise programs on disease-specific QoL of patients with AF are unclear. Understanding the long-term effect of exercise programs on symptoms and quality of life is essential to improve the management of the unique needs of patients with AF. Purpose To assess the long-term effects of 12 weeks of HIIT- and MICT-based cardiovascular rehabilitation (CR) on disease-specific QoL in patients with persistent and permanent AF. Methods A randomized clinical trial with patients with persistent and permanent AF randomized (1:1) to either 12 weeks of MICT or HIIT. Disease-specific QoL was assessed using the AFSS, a 19-item self-report validated questionnaire with the following subscales: (1) global well-being, (2) AF total burden (comprising frequency, duration, and severity of AF), and (3) AF symptom score in the previous four weeks. A linear mixed-effect model with repeated measures over time (i.e., baseline, week 12, week 26, 1-year, and 2-year) was used to examine the main effects of time, group, and time by group interactions. The maximum likelihood estimation method was used to address missingness. A p-value of &amp;lt; 0.05 was set for statistical significance. Results The study included 86 participants (mean [SD] age, 69[8] years; 57[66.3%] males). The global well-being scores varied significantly (Time F=17.4, p&amp;lt;0.001) across the two years, irrespective of the exercise program, with a significant decrease at week 26, when compared to week 12 (p&amp;lt;0.001, mean difference[MD]=-5.0 pts) and baseline (p&amp;lt;0.001, MD=-4.6 pts). Next, global well-being increased in years 1 and 2 to similar values from week 12. The frequency of AF was significantly lower (Time F=23.6, p&amp;lt;0.001) at week 26 when compared to week 12 (p&amp;lt;0.001, MD = -0.9 pts), but increased at year 1 (p&amp;lt;0.001, MD=2.4 pts). AF symptom score (Time F=5.0, p=0.004) was lower at week 26 when compared to baseline (p=0.03, MD=-2.6 pts). A significant time by group interaction was observed for AF total burden (F=3.1, p=0.01). Both groups presented a decrease in AF total burden from week 12 to week 26 (p&amp;lt;0.001 both, HIIT MD=-6.4 points; MICT MD=-7.8 pts), followed by an increase to year 1 (p&amp;lt;0.001 both, HIIT MD=6.6 pts; MICT MD=8.0 pts). From year 1 to 2, AF total burden decreased only in HIIT (p&amp;lt;0.001, MD=-5.6 pts). There were no significant changes in the severity and duration of AF. Conclusion No long-term decreases in global well-being or AF symptoms for both groups, although a more pronounced reduction in AF total burden was observed in the HIIT group.

High-intensity interval training (HIIT) is effective for generating positive cardiovascular health and fitness benefits. This study compared HIIT and moderate-intensity continuous training (MICT) for affective state and enjoyment in sedentary males with overweight or obesity. Twenty-eight participants performed stationary cycling for 6 weeks × 3 sessions/week. Participants were randomly allocated to HIIT (N=16) (10 × 1-minute intervals at ~90% peak heart rate) or MICT (N=12) (30 minutes at 65-75% peak heart rate). Affective state changes were assessed after 6-weeks training. Enjoyment and acute change in affect were assessed after individual training sessions. HIIT participants reported improved positive affect following 6 weeks training (∆ 3.6 ± 4.6, p = 0.007, effect size d = 0.70), without corresponding improvement in negative affect (p = 0.48, d = -0.19). MICT did not induce any improvement in positive affect (p = 0.56, d = 0.16) or negative affect (p = 0.23, d = -0.41). Enjoyment ratings were comparable for both exercise formats (HIIT: 4.4 ± 0.4 on a 7-point scale; MICT: 4.3 ± 0.3; p = 0.70, d = 0.15). Six weeks of HIIT induced improvement in positive affect in sedentary participants with overweight or obesity. Enjoyment of training was only slightly above neutral levels for both training formats. What’s already known about this topic? Exercise training can improve general affect however the optimal exercise characteristics for improving affect are unclear. Studies assessing the relative enjoyment of HIIT in comparison to MICT have largely been equivocal to date. What does this study add? HIIT can improve affective state in males with overweight or obesity. Six weeks of stationary cycling HIIT were rated as only mildly enjoyable, comparable to ratings for MICT.

Aims: In recent years, consumption of nutrition supplements such as LArginine has increased in athletes in order to increase efficiency and reduce fatigue. The purpose of the present study was to examine the effects of 4 weeks of high-intensity interval training (HIT) with and without L-Arginine supplementation on anaerobic and aerobic performance in women’s futsal players. Materials & Methods: In this research study (2013), 20 healthy women futsal players in Kermanshah City, Iran, were selected by available sampling method. Subjects were randomly divided into two groups; training-supplement (n=10) and training-placebo (n=10). Both groups, in addition to futsal specific training, performed RAST (anaerobic sprint test) test as high-intensity interval training protocol, 2 sessions per week for 4 weeks. Before and after the training protocol, subjects performed Bruce and RAST tests in order to measure aerobic and anaerobic power, respectively. Blood samples were collected 30 seconds after the RAST test to measure the levels of serum lactate concentration. All data were analyzed using independent T and paired T tests. Findings: After the training, both groups showed significant increasing in VO2max and anaerobic power (p<0.05) and significant decreasing in blood lactate concentrations (p<0.05); percentage of changes were greater for the first than the second group in all three factors. Conclusion: Using high-intensity interval training in combination with LArginine lead to improvement of aerobic and anaerobic fitness in women futsal players.

This study investigated the effects of 10 weeks of crossover point (COP) exercise training and high-intensity interval training (HIIT) on cardiovascular risk factors and vascular health in overweight young women. Overweight young women were randomized into HIIT and COP groups. Participants in the HIIT group (n=10; age=22±2, body mass index (BMI)=25.72±0.90) and COP group (n=10, age=21±2, BMI=25.90±1.90) took part in 10 weeks of HIIT and COP exercise training, respectively. Cardiorespiratory fitness, cardiovascular health, and oxidative stress indicators were measured before and after the intervention period. After 10 weeks of exercise intervention, both COP exercise and HIIT led to a significant increase in maximal oxygen uptake (p<0.001). The systolic blood pressure (p=0.006), diastolic blood pressure (p=0.006), and brachial-ankle pulse wave velocity (p=0.002) were significantly decreased in both COP group and HIIT group, while serum interleukin-6 levels were increased in HIIT and COP groups. The present study shows that a training program at COP could be an effective strategy to protect vascular health.

To investigate the effects of high-intensity interval training (HIT) on physical fitness and cardiometabolic health in youth with physical disabilities. For this quasi-experimental study 70 participants were recruited from schools for special education and divided into runners and users of wheelchairs. HIT was performed for 8 weeks, twice a week, containing 30 seconds all-out exercises. Exercise adherence was 84.5%. Following HIT, there were improvements in anaerobic performance, agility, aerobic performance, and systolic and diastolic blood pressure. There were no changes in peak oxygen uptake ((Equation is included in full-text article.)O2peak), arterial stiffness, body composition, lipid profile, and fasting glucose. Both anaerobic and aerobic performance improved after HIT, with no changes in (Equation is included in full-text article.)O2peak. There were no effects on cardiometabolic health, except for a decrease in blood pressure.

It is accepted that regular exercise improves indices of cardiovascular health including resting blood pressure (BP) and blood pressure reactivity. A commonly cited barrier to exercise is time. High-intensity interval training (HIIT) reduces the time demands of exercise compared to moderate-intensity continuous training (MCT), however the effect of HIIT on resting BP and BP reactivity has not been investigated. Objective: To determine the effect of HIIT on resting BP and BP reactivity compared to MCT. Hypothesis: We hypothesized that 8 weeks of HIIT would result in reductions in resting BP and BP reactivity similar to MCT. Methods: Sedentary adults (5M/11F, age: 29 ± 2) were randomly assigned to either 8 weeks (3 sessions/week) of HIIT or MCT. Participants performed a graded exercise test on a cycle ergometer to establish baseline cardiorespiratory fitness and determine maximal heart rate to set training intensities. Resting systolic and diastolic blood pressure (SBP and DBP, respectively) and mean arterial pressure (MAP) were recorded by an oscillometric device. A Finometer was used to measure beat-to-beat BP during the sympatho-excitatory stressors which included 2 minutes of isometric handgrip exercise (HG) at 40% of maximal voluntary contraction, followed immediately by 3 minutes of post-exercise ischemia (PEI). Cardiorespiratory and blood pressure assessments were repeated post-intervention. Results: SBP decreased post-training in both groups (HIIT: 112 ± 4mmHg to 105 ± 3mmHg, p&lt;0.05; MCT: 119 ± 2 to 115 ± 3, p&lt;0.05). There was a main effect for a decrease in DBP following training (HIIT: 69 ± 3 to 67 ± 3; MCT: 73 ± 3 to 69 ± 2, p&lt;0.05). A main effect was also observed for a decrease in MAP following training (HIIT: 83 ± 3 to 80 ± 3; MCT: 88 ± 2 to 85 ± 2, p&lt;0.01). Analysis of BP reactivity during HG revealed a significant interaction (p&lt;0.05) across all measures. BP reactivity was reduced in the MCT group as measured by ΔSBP (24 ± 3 to 18 ± 3, p&lt;0.05), ΔMAP (23 ± 2 to 17 ± 2, p&lt;0.01) and ΔDBP (23 ± 2 to 16 ± 2, p&lt;0.01). No changes in BP reactivity were observed in the HIIT group. Analysis of BP during PEI revealed a significant interaction (p&lt;0.05) across all measures. HIIT augmented ΔSBP (14 ± 3 to 20 ± 4, p&lt;0.05) during PEI and a trend was observed for ΔMAP (p=0.056) whereas MCT resulted in no differences pre to post intervention. Conclusion: These data suggest that both HIIT and MCT interventions can improve resting BP in sedentary individuals; however, there appears to be a divergent effect of HIIT and MCT on BP reactivity in response to HG suggesting a heightened metaboreflex following HIIT which requires further study. NIH Grant P20GM113125 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.