High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis

Faster age-related decline in cardiorespiratory fitness in rheumatoid arthritis patients: an observational study in the Trøndelag Health Study

Primary aim: Compare change in estimated cardiorespiratory fitness (eCRF change) in rheumatoid arthritis (RA) patients with population-based age- and sex-matched controls during ~ 11-year follow-up and identify variables associated with eCRF change. Secondary aim: Compare eCRF level in RA patients and controls. eCRF change from the second (HUNT2 1995–1997) to the third (HUNT3 2006–2008) surveys of the Norwegian Trøndelag Health Study was compared between RA patients (n = 188) and controls (n = 26,202) attending both surveys. Predictors of eCRF change were identified by Lasso regression followed by multiple linear regression. Mean eCRF level in RA patients (n = 436) and controls (n = 67,910) was compared using age-adjusted linear regression stratified on sex, as well as two-sample t tests including RA patients (n = 432) and controls (n = 59,124) who attended either HUNT2, HUNT3 or both HUNT2 and HUNT3. The mean eCRF decline from HUNT2 to HUNT3 in RA patients was 8.3 mL min⁻¹ kg⁻¹ versus 6.7 mL min⁻¹ kg⁻¹ in controls (p < 0.001). The decline was faster in RA patients and larger with higher baseline age (standardized regression coefficient for RA patients: (− 0.482 × age + 0.044); controls: (− 0.367 × age, p < 0.001). The decline was also associated with smoking, cardiovascular disease, increasing body mass index, asthma, and hypertension. Mean differences in age-adjusted eCRF level for RA patients versus controls (p < 0.001): women HUNT2: − 3.2 mL min⁻¹ kg⁻¹; HUNT3: − 5.0 mL min⁻¹ kg⁻¹; men HUNT2: − 1.8 mL min⁻¹ kg⁻¹; HUNT3: − 4.0 mL min⁻¹ kg⁻¹. Higher age at baseline was associated with faster decline in eCRF. This change was more pronounced in RA patients than controls, indicating a larger negative effect on fitness of aging in RA. RA patients had lower eCRF compared to healthy individuals.

Moderate-Intensity Continuous Training or High-Intensity Interval Training with or without Resistance Training for Altering Body Composition in Postmenopausal Women

PURPOSE

This study aimed to compare body composition changes induced by moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), or HIIT + resistance training (RT) programs (3 d·wk, 12 wk) in overweight/obese postmenopausal women, and to determine whether fat mass reduction is related to greater fat oxidation (FatOx).

METHODS

Participants (n = 27) were randomized in three groups: MICT (40 min at 55%-60% of peak power output), HIIT (60 × 8 s at 80%-90% of peak HR, 12 s active recovery), and HIIT + RT (HIIT + 8 whole-body exercises: 1 set of 8-12 repetitions). Dual-energy x-ray absorptiometry was used to measure whole-body and abdominal/visceral fat mass (FM) and fat-free mass. FatOx was determined at rest, during a moderate-intensity exercise (40 min at 50% of peak power output), and for 20 min postexercise, before and after training.

RESULTS

Overall, energy intake and physical activity levels did not vary from the beginning to the end of the intervention. Body weight and total FM decreased in all groups over time, but significant abdominal/visceral FM losses were observed only in HIIT and HIIT + RT groups. When expressed in percentage, total FM, fat-free mass, and muscle mass were significantly modified only by HIIT + RT training. FatOx did not change at rest but increased similarly in the three groups during and after exercise. Therefore, the HIIT-induced greater FM loss was not related to higher FatOx during or after exercise.

CONCLUSIONS

MICT or HIIT ± RT could be proposed to nondieting postmenopausal women who are overweight/obese to decrease weight and whole-body FM. The HIIT programs were more effective than MICT in reducing abdominal/visceral FM. RT addition did not potentiate this effect but increased the percentage of muscle mass.

Cardiometabolic Effects of High-Intensity Hybrid Functional Electrical Stimulation Exercise after Spinal Cord Injury

INTRODUCTION

The prevalence of cardiometabolic disease following spinal cord injury is known to be high. However, it is unknown whether engaging in high-intensity exercise, which is advocated by recent guidelines, is beneficial or feasible for these individuals.

OBJECTIVE

To assess the effects of high-intensity, whole-body exercise on the prevalence of cardiometabolic disease in individuals with spinal cord injury.

DESIGN

Combination of a randomized controlled trial and an open label intervention study of functional electrical stimulation legs plus arms rowing.

SETTING

Outpatient academic rehabilitation hospital.

PARTICIPANTS

Forty individuals with spinal cord injury, with American Spinal Injury Association (ASIA) impairments scales A-D and neurological levels of injury C1-T12.

INTERVENTION

Six months of high-intensity, hybrid-functional electrical stimulation rowing.

MAIN OUTCOME MEASURES

Change in VO_2max , serum lipids, and insulin resistance, prevalence of cardiometabolic disease.

RESULTS

Individuals averaged 42.1 ± 22.0 minutes of hybrid-functional electrical stimulation rowing a week over an average of 1.69 sessions per week over the 6 months of intervention. This amounted to an average of 170.9 ± 100 km rowed, at a mean heart rate of 82.7% of individualized maximum. Only one of 40 individuals met current exercise guidelines for the full 6 months. VO_2max increased significantly (P < .001), yet prevalence of cardiometabolic disease did not change significantly (decrease from 22.5% to 20%, P = .70). Hemoglobin A1c did decrease significantly over this time (P = .01), although serum lipids and fasting glucose/insulin levels were unchanged. In exploratory subanalyses assessing individuals injured ≤12 months, those with more chronic injuries decreased their triglyceride-to-high-density lipoprotein (HDL) ratio (P = .04), a marker of cardiac mortality. Stratifying by neurological level of injury, individuals with paraplegia had worsened low-density lipoprotein (LDL) level (P = .02) and total cholesterol-to-HDL ratio (P = .04) over the 6-month intervention.

CONCLUSIONS

Sustained high-intensity exercise with hybrid functional electrical stimulation rowing does not decrease the prevalence of cardiometabolic disease after spinal cord injury.

Football - Novel Approaches to Tackle Diabetes

Balanced diet and regular physical activity are of key importance to the prevention of the development and progression of non-communicable diseases. In 2050, 50% of the European population is expected to be obese. Cardiovascular diseases, diabetes mellitus, cancer, as well as joint impairments, will further increase. Therefore, programmes are critical to the improvement of the population's health status in the long run. New ways have to be found that allow addressing more people than with the current approaches. Football has a great potential to attract people at risk for or with already existing non-communicable diseases, such as type 2 diabetes, to participate in health-promoting programmes. The novel football version, walking football was developed for elderly players, aiming at avoiding injuries and physical overload. The present article gives a brief overview on the metabolic effects of recreational football, particularly walking football, as well as health-promoting programmes offered by professional football clubs in humans at risk for or with already existing non-communicable diseases.

High-Intensity Interval Training Decreases Muscle Sympathetic Nerve Activity in Men With Essential Hypertension and in Normotensive Controls

Exercise training is a cornerstone in reducing blood pressure (BP) and muscle sympathetic nerve activity (MSNA) in individuals with essential hypertension. High-intensity interval training (HIIT) has been shown to be a time efficient alternative to classical continuous training in lowering BP in essential hypertension, but the effect of HIIT on MSNA levels has never been investigated. Leg MSNA responsiveness to 6 weeks of HIIT was examined in 14 hypertensive men (HYP; age: 62 ± 7 years, night time BP: 136 ± 12/83 ± 8 mmHg, BMI: 28 ± 3 kg/m²), and 10 age-matched normotensive controls (NORM; age: 60 ± 8 years, night time BP: 116 ± 2/68 ± 4 mmHg and BMI: 27 ± 3 kg/m²). Before training, MSNA levels were not different between HYP and NORM (burst frequency (BF): 41.0 ± 10.3 vs. 33.6 ± 10.6 bursts/min and burst incidence (BI): 67.5 ± 19.7 vs. 64.2 ± 17.0 bursts/100 heart beats, respectively). BF decreased (P < 0.05) with training by 13 and 5% in HYP and NORM, respectively, whereas BI decreased by 7% in NORM only, with no difference between groups. Training lowered (P < 0.05) night-time mean arterial- and diastolic BP in HYP only (100 ± 8 vs. 97 ± 5, and 82 ± 6 vs. 79 ± 5 mmHg, respectively). The change in HYP was greater (P < 0.05) compared to NORM. Training reduced (P < 0.05) body mass, visceral fat mass, and fat percentage similarly within- and between groups, with no change in fat free mass. Training increased (P < 0.05) V̇O₂-max in NORM only. Six weeks of HIIT lowered resting MSNA levels in age-matched hyper- and normotensive men, which was paralleled by a significant reduction in BP in the hypertensive men.

Is Structured Exercise Performed with Supplemental Oxygen a Promising Method of Personalized Medicine in the Therapy of Chronic Diseases?

Aim: This systematic review aimed to explore the literature to identify in which types of chronic diseases exercise with supplemental oxygen has previously been utilized and whether this type of personalized therapy leads to superior effects in physical fitness and well-being. Methods: Databases (PubMed/MEDLINE, CINHAL, EMBASE, Web of knowledge and Cochrane Library) were searched in accordance with PRISMA. Eligibility criteria included adult patients diagnosed with any type of chronic diseases engaging in supervised exercise training with supplemental oxygen compared to normoxia. A random-effects model was used to pool effect sizes by standardized mean differences (SMD). Results: Out of the identified 4038 studies, 12 articles were eligible. Eleven studies were conducted in chronic obstructive pulmonary disease (COPD), while one study included coronary artery disease (CAD) patients. No statistical differences were observed for markers of physical fitness and patient-reported outcomes on well-being between the two training conditions (SMD −0.10; 95% CI −0.27, 0.08; p = 0.26). Conclusions: We found that chronic exercise with supplemental oxygen has mainly been utilized for COPD patients. Moreover, no superior long-term adaptations on physical fitness, functional capacity or patient-reported well-being were found, questioning the role of this method as a personalized medicine approach. Prospero registration: CRD42018104649.

Four weeks of high-intensity interval training (HIIT) improve the cardiometabolic risk profile of overweight patients with type 1 diabetes mellitus (T1DM)

This study investigated the effects of a four-week HIIT intervention on the cardiometabolic risk profile, liver fat content, insulin requirement, hypoglycaemia, physical fitness, and health-related quality of life in patients with T1DM. A supervised exercise intervention with baseline to follow-up comparison between overweight (BMI = 28.6 ± 2.1 kg/m²) and normal weight (BMI = 23.2 ± 1.40 kg/m²) T1DM patients was performed. Eleven overweight (age = 40.7 ± 14.3 years) and 11 normal weight (age = 42.2 ± 15.5 years) T1DM patients performed a four-week, low-volume, all-out cycling HIIT (4-6 bouts, work/relief ratio 1:1) twice weekly. HIIT lowered low-density lipoprotein and uric acid levels in overweight patients by up to 10.5% (vs. normal weight, p≤0.0312). HbA1c, high-density lipoprotein, and triglyceride levels did not change in any of the groups. Participants' maximal exercise capacity and power output at individual anaerobic lactate threshold increased to an equal extend of up to 10% (p≤0.0002) in both groups. During the intervention, participants used fewer daily bolus insulin (-5.22 ± 12.80%) and less total units of insulin (-4.42 ± 10.20%, p≤0.023) compared to the pre-intervention period with no between-group difference. Overall, the average daily number of hypoglycaemias increased from 0.90 ± 0.56-1.08 ± 0.63 during the intervention (p = 0.033). SF-36 subscales showed higher scores after the intervention, with a significant improvement of "role limitations due to physical problems" (p<0.05) for both groups. We conclude that in T1DM, HIIT may exert beneficial effects on physical fitness, insulin requirement and health-related quality of life. Of note, beneficial HIIT effects on the cardiometabolic risk profile in T1DM may be larger in overweight T1DM patients.

The Role of Exercise in Patients with Obesity and Hypertension

PURPOSE OF REVIEW

This review sought to evaluate the role of exercise in patients with obesity and comorbid hypertension, with a focus on contemporary literature (since January 2015).

RECENT FINDINGS

No reviews have included patients classified with both obesity and hypertension and there is a paucity of randomised controlled trials examining the benefits of exercise in this population. Moreover, just one of 19 reviews examining the role of exercise on blood pressure included studies that met pre-defined inclusion criterion for hypertension, although seven conducted subgroup analyses stratified by mean baseline blood pressure. These demonstrated significantly larger reductions in blood pressure in hypertensive than pre-hypertensive and normotensive samples. There is a significant research-practice gap for understanding and influencing the role of exercise for patients with obesity and hypertension. This review provides recommendations for future research and consensus-based recommendations that promote exercise as a principle therapy for patients with obesity and hypertension.

Effect of High-Intensity Interval Training on Glycemic Control in Adults With Type 1 Diabetes and Overweight or Obesity: A Randomized Controlled Trial With Partial Crossover

OBJECTIVE

To study the effect of 12 weeks of high-intensity interval training (HIIT) on glycemic control in adults with type 1 diabetes and overweight or obesity.

RESEARCH DESIGN AND METHODS

Thirty inactive adults with type 1 diabetes who had BMI ≥25 kg/m² and HbA_1c ≥7.5% were randomized to 12 weeks of either HIIT exercise intervention consisting of 4 × 4-min HIIT (85-95% peak heart rate) performed thrice weekly or usual care control. In a partial crossover design, the control group subsequently performed the 12-week HIIT intervention. The primary end point was the change in HbA_1c from baseline to 12 weeks. Glycemic and cardiometabolic outcomes were measured at 0, 12, and 24 weeks.

RESULTS

Participants were aged 44 ± 10 years with diabetes duration 19 ± 11 years and BMI 30.1 ± 3.1 kg/m². HbA_1c decreased from 8.63 ± 0.66% at baseline to 8.10 ± 1.04% at 12 weeks in the HIIT intervention group (P = 0.01); however, this change was not significantly different from the control group (HIIT -0.53 ± 0.61%, control -0.14 ± 0.48%, P = 0.08). In participants who undertook at least 50% of the prescribed HIIT intervention, the HbA_1c reduction was significantly greater than control (HIIT -0.64 ± 0.64% [n = 9], control -0.14 ± 0.48% [n = 15], P = 0.04). There were no differences in insulin dose, hypoglycemia on continuous glucose monitoring, blood pressure, blood lipids, body weight, or body composition between groups.

CONCLUSIONS

Overall, there was no significant reduction in HbA_1c with a 12-week HIIT intervention in adults with type 1 diabetes. However, glycemic control may improve for people who undertake HIIT with greater adherence.

The effect of exercise training on cardiometabolic health in men with prostate cancer receiving androgen deprivation therapy: a systematic review and meta-analysis

BACKGROUND

Growing evidence suggests that men exposed to androgen deprivation therapy (ADT) have an increased risk of cardiovascular disease. While exercise has shown to attenuate some adverse effects of ADT, the effects on cardiometabolic health have not been systematically evaluated.

OBJECTIVE

To evaluate the effect of exercise on cardiometabolic health in men with prostate cancer (PCa) receiving ADT.

METHODS

A systematic literature search of MEDLINE, EMBASE, CINHAL, SCOPUS, WEB OF SCIENCE and SPORTSDICUS from database inception to April 2020 was performed. A quantitative synthesis using Cohens d effect size and a meta-analysis using random-effects models were conducted.

RESULTS

Overall, fourteen randomised controlled trials (RCTs) and four non-randomised studies were included. Eleven RCTs (n = 939 patients) were included in the meta-analysis. Exercise training improved the 400-m-walk test (MD -10.11 s, 95% CI [-14.34, -5.88]; p < 0·00001), diastolic blood pressure (-2.22 mmHg, [-3.82, -0.61]; p = 0.007), fasting blood glucose (-0.38 mmol/L, [-0.65, -0.11]; p = 0.006), C-reactive protein (-1.16 mg/L, [-2.11, -0.20]; p = 0.02), whole-body lean mass (0.70 kg, [0.39, 1.01]; p < 0.0001), appendicular lean mass (0.59 kg, [0.43, 0.76]; p < 0.00001), whole-body fat mass (-0.67 kg, [-1.08, -0.27]; p = 0.001), whole-body fat percentage (-0.79%, [-1.16, -0.42]; p < 0.0001), and trunk fat mass (-0.49 kg, [-0.87, -0.12]; p = 0.01), compared to usual care. No significant effects on systolic blood pressure or blood lipid metabolism were detected.

CONCLUSIONS

In a small subset of evaluated studies, exercise may favourably improve some but not all markers of cardiometabolic health. Future exercise intervention trials with cardiometabolic outcomes as primary endpoints are needed to confirm these initial findings.

Effect of high-intensity interval training on cardiorespiratory fitness, physical activity and body composition in people with schizophrenia: a randomized controlled trial

BACKGROUND

Exercise may improve cardiorespiratory fitness in people with schizophrenia, however, possible condition-specific cardiorespiratory disadvantages, a scarcity of methodologically sound studies, and conflicting results raise questions about the effect of exercise on maximal oxygen uptake (VO2max) in this group. The primary aim of this study, therefore, was to investigate the effect of high-intensity interval training on VO2max in people with schizophrenia. Second, we sought to determine whether the intervention would have an effect on general physical activity (PA) level and body composition.

METHODS

Eighty-two patients with schizophrenia were randomly assigned to supervised high-intensity interval training or computer gaming skills training, performed twice a week for 12 weeks. Oxygen uptake was measured directly, during a maximum exercise session on a treadmill. PA level were assessed using ActiGraph accelerometer, and body composition was assessed by bioelectrical impedance. Differences between groups were assessed by analysis of variance using a univariate general linear model.

RESULTS

There were no significant differences between the groups on any of the cardiorespiratory variables neither at baseline nor after the program. There were also no significant within-group differences in any of the cardiorespiratory fitness variables between the baseline and post-program time points, despite that 61% of the participants performing high-intensity interval training showed a significant increase in workload on the treadmill. However, 47% of the participants in the high-intensity interval training group had a ≥ 5% increase in VO2max. Participants supervised by mental health care providers with PA competence (e.g. rehabilitation center staff, sport scientist, physical trainer) had a much larger increase in VO2max compared to participants supervised by mental health workers without such competence, and when adding PA competence to the model, the intervention group increased VO2max significantly compared to the comparison group. The intervention had no significant effect on PA level or body composition.

CONCLUSIONS

The intervention did not improve VO2max, PA level or body composition but succeeded in increasing workload on the treadmill. With regard to VO2max, approximately half of the patients may be considered responders.

TRIAL REGISTRATION

ClinicalTrials.gov ; NCT02205684 , registered July 2014.

H″IT″ting the Barriers for Exercising during Social Isolation

Aerobic exercise is traditionally recommended to improve general health and prevent many non-communicable diseases. However, the measures adopted to control the novel Coronavirus (COVID-19) outbreak culminated with closing of exercise facilities and fitness centers and, as a primary consequence, impaired aerobic exercise practice. This contributed to an increase in risk factors associated with physical inactivity such as insulin resistance, high blood pressure, low-grade inflammation, weight gain, and mental health problems. The scenario is worrisome, and it is important to propose alternatives for exercise practice during the COVID-19 pandemic. Interval training (IT) emerges as an exercise mode that might be feasible, low-cost, and potentially safe to be performed in many different places. IT consists of interspersing relative brief bouts of high-intensity exercise with recovery periods and promotes similar or greater health benefits when compared to moderate-intensity continuous exercise. Among the different types of IT, sprint interval training and "Tabata protocols" might be particularly useful during social isolation. These protocols can be controlled and performed without the need of complex equipment and can be adapted to different places, including domestic environments. In this article, we present variations of IT as possible alternatives to cope physical inactivity during COVID-19 pandemics with a focus on its practical applications. The protocols suggested can be performed without the need of specialized equipment or facilities, in a time-efficient manner, and aiming to prevent detraining or even improve physical fitness and general health.

Acute partial sleep deprivation and high-intensity interval exercise effects on postprandial endothelial function

PURPOSE

Acute-total and chronic-partial sleep deprivation increase the risks for cardiovascular disease (CVD). Cardiovascular function assessed by flow mediated dilation (FMD) is reduced after sleep deprivation. High-intensity interval exercise (HIIE) improves postprandial FMD. Sleep-deprived individuals may practice HIIE followed by a high-fat breakfast. This study investigated the acute-partial sleep deprivation (APSD) and HIIE interaction on postprandial FMD.

METHODS

Fifteen healthy males (age 31 ± 5 years) participated in: (a) reference sleep (~ 9.5 h) with no HIIE (RS), (b) RS and HIIE (RSX), and (c) APSD and HIIE (SSX). HIIE was performed in 3:2 min intervals at 90% and 40% of VO₂ reserve. FMD was assessed the night before (D1), the morning of the next day (D2), 1 h (1hrPE) and 4 h post HIIE (4hrPE).

RESULTS

FMD% change was lower at RS compared to both RSX (F_1,14 = 23.96, p < 0.001, η² = 0.631) and SSX (F_1,14 = 4.8, p = 0.47, η² = 0.253) at 1hrPE. RSX and SSX did not differ at 1hrPE (F_1,14 = 0.2, p = 0.889, η² = 0.001), but SSX elicited greater FDM responses. Absolute FMD change was lower at RS compared to both RSX (F_1,14 = 21.5, p < 0.001, η² = 0.606) and SSX (F_1,14 = 7.01, p = 0.019, η² = 0.336) at 1hrPE. RSX and SSX did not differ at 1hrPE (F_1,14 = .03, p = 0.858, η² = 0.002), but SSX elicited greater FDM responses.

CONCLUSIONS

HIIE short-term effects on cardiovascular function remain cardioprotective even after an acute-partial sleep deprivation.

Can Active Aerobic Exercise Reduce the Risk of Cardiovascular Disease in Prehypertensive Elderly Women by Improving HDL Cholesterol and Inflammatory Markers?

This study aims to verify the efficacy of exercise programs designed to prevent and treat hypertension-induced cardiovascular disease (CVD) by analyzing the effects of a 6-month active aerobic exercise program, administered to prehypertensive elderly women, on reducing the risk of developing CVD by enhancing their physical fitness level and improving the detailed markers of high-density lipoprotein cholesterol (HDL-C) and inflammatory markers. We assigned the elderly women (≥65 years) recruited into normal blood pressure (120–129/80–84; NBP, n = 18) and high-normal blood pressure (130–139/85–89; HNBP, n = 12) groups according to the European guidelines for the management of arterial hypertension. The exercise program was made up of combined workouts of elastic band resistance exercise and aerobics with dance music. The program took place three times a week for six months, with each session lasting 60 min. We measured pre- and post-intervention body composition, blood pressure, physical fitness level, blood lipids profile, HDL-C, SAA, TNF-α, IL-6, IL-4, IL-15, CRP, and HSP70 and calculated the Framingham risk scores for comparison. A significant post-intervention reduction in the mean systolic blood pressure (SBP) was observed in the HNBP group (p < 0.001), with significant increase in HDL-C (p < 0.01) and significant decrease in serum amyloid A (SAA) concentration (p < 0.01). A significant improvement in physical fitness factors such as physical efficiency index (PEI) was also observed in the HNBP group (p < 0.05). The post-intervention TNF-α, IL-6, and SAA concentrations were more significantly lower in the HNBP than in the NBP group (p < 0.05). Compared to the baseline values, a significant decrease in SAA concentration (p < 0.01) and significant increase in HSP70 concentration (p < 0.001) were observed in the HNBP group. The HNBP group’s 10-year CVD risk was also significantly reduced (p < 0.05). The pre–post differences in SBP and DBP were significantly correlated with those in the anti-inflammatory markers IL-4 and IL-15 (p < 0.01). In conclusion, the 6-month active aerobic exercise program of moderate intensity administered to prehypertensive elderly women (≥65 years) had the effect of reducing the 10-year CVD risk through a substantial reduction in SBP, overall physical fitness improvement, increase in HDL-C, decrease in SAA concentration, and substantial decrease in inflammatory biomarkers. It was also confirmed that an increase in anti-inflammatory markers, which showed a small range of increase with respect to the decrease in blood pressure, may have a major effect.

Exercise intensity and cardiovascular health outcomes after 12 months of football fitness training in women treated for stage I-III breast cancer: Results from the football fitness After Breast Cancer (ABC) randomized controlled trial

PURPOSE

To examine the exercise intensity and impact of 12 months of twice-weekly recreational football training on cardiorespiratory fitness (CRF), blood pressure (BP), resting heart rate (HR_rest), body fat mass, blood lipids, inflammation, and health-related quality of life in women treated for early-stage breast cancer (BC).

METHODS

Sixty-eight women who had received surgery for stage I-III BC and completed adjuvant chemo- and/or radiation therapy within 5 years were randomized in a 2:1 ratio to a Football Fitness group (FFG, n = 46) or a control group (CON, n = 22). Football Fitness sessions comprised a warm-up, drills and 3-4 × 7 min of small-sided games (SSG). Assessments were performed at baseline, 6 months and 12 months. Outcomes were peak oxygen uptake (VO₂peak), blood pressure (BP), HR_rest, total body fat mass, and circulating plasma lipids and hs-CRP, and the 36-Item Short Form Health Survey (SF36). Intention-to-treat (ITT) analyses were performed using linear mixed models. Data are means with SD or 95% confidence intervals.

RESULTS

Adherence to training in participants completing the 12-months follow-up (n = 33) was 47.1% (22.7), and HR during SSG was ≥80% of HR_max for 69.8% (26.5) of total playing time. At baseline, VO₂peak was 28.5 (6.4) and 25.6 (5.9) ml O₂/kg/min in FFG and CON, respectively, and no significant changes were observed at 6- or 12 months follow-up. Systolic BP (SBP) was 117.1 (16.4) and 116.9 (14.8) mmHg, and diastolic BP (DBP) was 72.0 (11.2) and 72.4 (8.5) mmHg in FFG and CON, respectively, at baseline, and a 9.4 mmHg decrease in SBP in CON at 12 months resulted in a between-group difference at 12 months of 8.7 mmHg (p = .012). Blood lipids and hs-CRP were within the normal range at baseline, and there were no differences in changes between groups over the 12 months. Similarly, no differences between groups were observed in HR_rest and body fat mass at 6- and12-months follow-up. A between-group difference in mean changes of 23.5 (0.95-46.11) points in the role-physical domain of the SF36 survey favored FFG at 6 months.

CONCLUSION

Football Fitness training is an intense exercise form for women treated for breast cancer, and self-perceived health-related limitations on daily activities were improved after 6 months. However, 1 year of Football Fitness training comprising 1 weekly training session on average did not improve CRF, BP, blood lipids, fat mass, or HR_rest.

TRIAL REGISTRATION NUMBER

The trial was registered at ClinicalTrials.gov with identifier NCT03284567.

Affective responses to high-intensity interval training with continuous and respite music

Music has been shown to enhance affective responses to continuous exercise, but the most effective application of music during interval exercise is poorly understood. This study examined two contrasting applications of music designed to assuage the decline in pleasure often experienced during high-intensity interval training (HIIT). In a repeated measures crossover design, 18 recreationally active participants (10 men and 8 women; M _age = 25.1 ± 5.1 years; M _BMI = 23.08 ± 2.01 kg/m 2; M VO_2max = 38.82 ± 10.73 ml/kg/min) completed three HIIT sessions (10 x 60 s efforts at 100% Wmax, separated by 75 s recovery) on a cycle ergometer. Participants completed two experimental conditions: respite music (applied only during the recovery periods), continuous music (applied throughout the entire HIIT session); and a no-music control condition. Results indicated that music did not influence affective valence during the work bouts or recovery periods of the HIIT sessions (ps >.05), but that listening to music continuously elicited greater post-task enjoyment (p =.032, d = 0.66) and remembered pleasure (p =.044, d = 0.5). This study is the first to investigate the application of music during a practical HIIT protocol and to compare the effects of respite versus continuous music during interval exercise.

Acute Effect of Interval vs. Continuous Exercise on Blood Pressure: Systematic Review and Meta-Analysis

Fundamento

O exercício aeróbio contínuo (EC) é uma das principais recomendações não farmacológicas para prevenção e tratamento da hipertensão arterial sistêmica. O EC é seguro e eficaz para reduzir a pressão arterial cronicamente, assim como nas primeiras horas após sua realização, fenômeno conhecido por hipotensão pós-exercício (HPE). O exercício intervalado (EI) também gera HPE.

Objetivo

Essa revisão sistemática e metanálise buscou comparar a magnitude da HPE entre o EC e EI em adultos.

Métodos

Realizou-se uma revisão sistemática de estudos publicados em revistas indexadas nas bases PubMed, Web of Knowledge, Scopus e CENTRAL até março de 2020 que compararam a magnitude da HPE entre o EC versus EI. Foi definida HPE entre 45 e 60 minutos pós-exercício. As diferenças entre grupos sobre a pressão arterial foram analisadas por meio do modelo de efeito aleatório. Os dados foram reportados como diferença média ponderada (WMD) e 95% de intervalo de confiança (IC). Valor p menor que 0,05 foi considerado estatisticamente significativo. A escala TESTEX (0 a 15) foi usada para verificação da qualidade metodológica dos estudos.

Resultados

O EI apresentou HPE de maior magnitude sobre a pressão arterial sistólica (WMD: -2,93 mmHg [IC95%: -4,96, -0,90], p = 0,005, I² = 50%) e pressão arterial diastólica (WMD: -1,73 mmHg [IC95%: -2,94, -0,51], p = 0,005, I² = 0%) quando comparado ao EC (12 estudos; 196 participantes). A pontuação dos estudos na escala TEXTEX variou entre 10 e 11 pontos.

Conclusões

O EI gerou HPE de maior magnitude quando comparado ao EC entre 45 e 60 minutos pós-exercício. A ausência de dados sobre eventos adversos durante o EI e EC nos estudos impede comparações sobre a segurança dessas estratégias. (Arq Bras Cardiol. 2020; 115(1):5-14)

Effects of 2 Methods of Combined Training on Cardiometabolic Risk Factors in Adolescents: A Randomized Controlled Trial

PURPOSE

To analyze the effects of 2 combined training methods on the cardiometabolic risk factors in adolescents.

METHODS

A total of 76 adolescents (16.1 [1.1] y, n = 44 female) were randomized into groups of moderate-intensity continuous training combined with resistance training (MICT + RT), high-intensity interval training combined with resistance training (HIIT + RT), or control. The training sessions were performed twice weekly for 12 weeks. The outcomes evaluated included body fat percentage, waist circumference, fasting blood glucose, fasting insulin, total cholesterol, triglycerides, low-density lipoprotein, high-density lipoprotein, glycated hemoglobin, insulin resistance index, blood pressure, peak oxygen consumption (VO2peak), and cardiometabolic risk Z score.

RESULTS

The intervention groups presented a significant reduction in the cardiometabolic risk Z score after 12 weeks of the combined exercise program. In relation to the cardiometabolic risk Z score between groups, the HIIT + RT group presented a significant intervention effect when compared with the control group (Cohen d = 0.23; P < .05). Significant intervention effects were found when comparing the MICT + RT and control groups for body fat percentage, high-density lipoprotein, and VO2peak. Between the HIIT + RT and control groups, significant intervention effects were found for body fat percentage, blood pressure, and VO2peak. There were not significant differences between the HIIT + RT and MICT + RT groups.

CONCLUSION

Twelve weeks of HIIT + RT and MICT + RT were effective in significantly reducing the cardiometabolic risk in these adolescents.

Circulating and Adipose Tissue miRNAs in Women With Polycystic Ovary Syndrome and Responses to High-Intensity Interval Training

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression post-transcriptionally. In women with polycystic ovary syndrome (PCOS), several miRNAs are differentially expressed compared to women without PCOS, suggesting a role for miRNAs in PCOS pathophysiology. Exercise training modulates miRNA abundance and is primary lifestyle intervention for women with PCOS. Accordingly, we measured the expression of eight circulating miRNAs selected a priori along with miRNA expression from gluteal and abdominal adipose tissue (AT) in 12 women with PCOS and 12 women matched for age and body mass index without PCOS. We also determined the miRNA expression “signatures” before and after high-intensity interval training (HIT) in 42 women with PCOS randomized to either: (1) low-volume HIT (LV-HIT, 10 × 1 min work bouts at maximal, sustainable intensity, n = 13); (2) high-volume HIT (HV-HIT, 4 × 4 min work bouts reaching 90–95% of maximal heart rate, n = 14); or (3) non-exercise control (Non-Ex, n = 15). Both HIT groups trained three times/week for 16 weeks. miRNAs were extracted from plasma, gluteal and abdominal AT, and quantified via a customized plate array containing eight miRNAs associated with PCOS and/or exercise training responses. Basal expression of circulating miRNA-27b (c-miR-27b), implicated in fatty acid metabolism, adipocyte differentiation and inflammation, was 1.8-fold higher in women with compared to without PCOS (P = 0.006) despite no difference in gluteal or abdominal AT miR-27b expression. Only the HV-HIT protocol increased peak oxygen uptake (VO₂peak L/min; 9%, P = 0.008). There were no changes in body composition. In LV-HIT, but not HV-HIT, the expression of c-miR-27b decreased (0.5-fold, P = 0.007). None of the remaining seven circulating miRNAs changed in LV-HIT, nor was the expression of gluteal or abdominal AT miRNAs altered. Despite increased cardiorespiratory fitness, HV-HIT did not alter the expression of any circulating, gluteal or abdominal AT miRNAs. We conclude that women with PCOS have a higher basal expression of c-miR-27b compared to women without PCOS and that 16 weeks of LV-HIT reduces the expression of this miRNA in women with PCOS. Intense exercise training had little effect on the abundance of the selected miRNAs within subcutaneous AT depots in women with PCOS.

Effects of high-intensity interval training compared with resistance training in prostate cancer patients undergoing radiotherapy: a randomized controlled trial

BACKGROUND

Exercise training has shown beneficial effects in the management of radiotherapy-related side effects in prostate cancer (PCa) patients undergoing radiation therapy (RT). However, the optimal modality of the exercise programs have not been yet determined. The aim of this randomized controlled trial was to investigate the effects of high-intensity interval training (HIIT) and resistance training (RES) compared to usual care (UC) on cancer-treatment-related fatigue (CTRF) (primary outcome), quality of life, depression, daytime sleepiness, insomnia, sleep quality, functional exercise capacity and executive function in PCa patients during RT.

METHODS

PCa patients undergoing RT with or without ADT were randomized in HIIT, RES or UC. Both exercise programs included three sessions per week during 5-8 weeks. HIIT consisted of 8-15 × 60 s intervals (≥85% maximal heart rate). RES was performed with 1-3 sets of 8-12 repetitions for each large muscle groups. The primary outcome was changed in CTRF measured with the Functional Assessment of Chronic Illness Therapy-Fatigue.

RESULTS

Seventy-two subjects (69.1 ± 8.2 years) completed the study. No exercise-related adverse events occurred. HIIT (p = 0.012) and RES (p = 0.039) training attenuated increases in CTRF compared to UC. Functional exercise capacity, evaluated by the 6-min walk test, increased after HIIT (p = 0 = 0.43) and RES (p = 0.041) compared to UC (+0.1%). No other secondary variables were different between groups.

CONCLUSIONS

Both intervention groups displayed beneficial effects on CTRF and functional exercise capacity in PCa patients undergoing RT. In addition, HIIT and RES are both safe with an excellent attendance rate to the exercise sessions.

High Intensity Training to Treat Chronic Nonspecific Low Back Pain: Effectiveness of Various Exercise Modes

High-intensity training (HIT) improves rehabilitation outcomes such as functional disability and physical performance in several chronic disorders. Promising results were also found in chronic nonspecific low back pain (CNSLBP). However, the impact of different exercise modes on HIT effectiveness in CNSLBP remains unclear. Therefore, this study evaluated the effectiveness of various HIT exercise modes and compared differences between these modes, on pain intensity, disability, and physical performance, as a therapeutic intervention for persons with CNSLBP. In a randomized comparative trial, consisting of a 12-week program, persons with CNSLBP were divided into four HIT groups, i.e., cardiorespiratory interval training coupled with either general resistance training, core strength training, combined general resistance and core strength training, or mobility exercises. Before and after the program, the Numeric Pain Rating Scale (NPRS), Modified Oswestry Disability Index (MODI), and Patient Specific Functioning Scale (PSFS) were recorded, and a cardiopulmonary exercise test (VO₂max, cycling time) and isometric trunk strength test (maximum muscle torque) were performed. Eighty participants (mean age: 44.0 y, 34 males) were included. Improvements were found within all groups after the HIT programs and ranged from −39 to −57% on the NPRS, +27 to +64% on the MODI, +38 to +89% on the PSFS, +7 to +14% on VO₂max, and +11 to +18% on cycling time. No differences between groups were found. High-intensity cardiorespiratory interval training improves CNSLBP rehabilitation outcomes when performed with other HIT exercise modes or mobility exercises. Hence, when setting up an exercise therapy program in CNSLBP rehabilitation, various HIT modes can be considered as therapy modalities.

The Molecular Adaptive Responses of Skeletal Muscle to High-Intensity Exercise/Training and Hypoxia

High-intensity exercise/training, especially interval exercise/training, has gained popularity in recent years. Hypoxic training was introduced to elite athletes half a century ago and has recently been adopted by the general public. In the current review, we have summarised the molecular adaptive responses of skeletal muscle to high-intensity exercise/training, focusing on mitochondrial biogenesis, angiogenesis, and muscle fibre composition. The literature suggests that (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) PGC-1α, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor 1-alpha (HIF1-α) might be the main mediators of skeletal muscle adaptations to high-intensity exercises in hypoxia. Exercise is known to be anti-inflammatory, while the effects of hypoxia on inflammatory signalling are more complex. The anti-inflammatory effects of a single session of exercise might result from the release of anti-inflammatory myokines and other cytokines, as well as the downregulation of Toll-like receptor signalling, while training-induced anti-inflammatory effects may be due to reductions in abdominal and visceral fat (which are main sources of pro-inflammatory cytokines). Hypoxia can lead to inflammation, and inflammation can result in tissue hypoxia. However, the hypoxic factor HIF1-α is essential for preventing excessive inflammation. Disease-induced hypoxia is related to an upregulation of inflammatory signalling, but the effects of exercise-induced hypoxia on inflammation are less conclusive. The effects of high-intensity exercise under hypoxia on skeletal muscle molecular adaptations and inflammatory signalling have not been fully explored and are worth investigating in future studies. Understanding these effects will lead to a more comprehensive scientific basis for maximising the benefits of high-intensity exercise.

Effect of high intensity interval training on body composition in women before and after menopause: a meta-analysis

NEW FINDINGS

What is the topic of this review? A meta-analysis of the efficacy of high intensity interval training (HIIT) in reducing weight, total fat mass (FM) and (intra)-abdominal FM in normal-weight and overweight/obese women before and after menopause. What advances does it highlight? HIIT programmes in women significantly decrease body weight and total and abdominal FM. Their effects are more evident in pre- than in postmenopausal women. Cycling HIIT seems more effective than running, especially in postmenopausal women, and training interventions longer than 8 weeks comprising three sessions a week should be promoted.

ABSTRACT

High-intensity interval training (HIIT) is a stimulating modality for reducing body weight and adipose tissue. The purpose of this meta-analysis was to assess the efficacy of HIIT in reducing weight, total fat mass (FM) and (intra)-abdominal FM in normal-weight and overweight/obese women before and after menopause. A structured electronic search was performed to find all publications relevant to our review. Stratified analyses were made of hormonal status (pre- vs. postmenopausal state), weight, HIIT modalities (cycling vs. running), programme duration (< or ≥8 weeks) and the methods used to measure body composition (dual-energy X-ray absorptiometry vs. computed tomography, Magnetic Resonance Imaging and others). A total of 38 studies involving 959 subjects were included. Our meta-analysis showed that overall HIIT programmes significantly decrease weight, total and abdominal FM in women. Both normal weight and overweight/obese women lost total FM after HIIT protocols whereas HIIT was only effective in decreasing abdominal FM in women with excess adiposity. When pre- and postmenopausal women were considered separately, the effect of HIIT on weight, total and abdominal FM were only significant before menopause. Cycling HIIT seemed more effective than running, especially in postmenopausal women, and training interventions longer than 8 weeks comprising three sessions were more efficient. HIIT is a successful strategy to lose weight and FM in normal weight and overweight/obese women. However, further studies are still needed to draw meaningful conclusions about the real effectiveness of HIIT protocols in postmenopausal women.

Physiological responses to moderate intensity continuous and high-intensity interval exercise in persons with paraplegia

STUDY DESIGN

Randomized crossover.

OBJECTIVES

To test differences in the duration and magnitude of physiological response to isocaloric moderate intensity continuous (MICE) and high-intensity interval exercise (HIIE) sessions in persons with spinal cord injury (SCI).

SETTING

Academic medical center in Miami, FL, USA.

METHODS

Ten adult men (mean ± s.d.; 39 ± 10 year old) with chronic (13.2 ± 8.8 year) paraplegia (T2-T10) completed a graded exercise test. Then, in a randomized order, participants completed MICE and HIIE for a cost of 120 kcal. MICE was performed at 24.6% PO_peak. During HIIE, exercise was completed in 2 min work and recovery phases at 70%:10% PO_peak.

RESULTS

MICE and HIIE were isocaloric (115.9 ± 21.8 and 116.6 ± 35.0 kcal, respectively; p = 0.903), but differed in duration (39.8 ± 4.6 vs 32.2 ± 6.2 min; p < 0.001) and average respiratory exchange ratio (RER; 0.90 ± 0.08 vs 1.01 ± 0.07; p = 0.002). During MICE, a workrate of 24.6 ± 6.7% PO_peak elicited a V̇O₂ of 53.1 ± 6.5% V̇O_2peak (10.1 ± 2.2 ml kg^-1 min^-1). During HIIE, a workrate at 70% PO_peak elicited 88.3 ± 6.7% V̇O_2peak (16.9 ± 4.2 ml kg^-1 min^-1), and 29.4 ± 7.7% of the session was spent at or above 80% V̇O_2peak. During HIIE working phase, RER declined from the first to last interval (1.08 ± 0.07 vs 0.98 ± 0.09; p < 0.001), reflecting an initially high but declining glycolytic rate.

CONCLUSIONS

Compared with MICE, HIIE imposed a greater physiological stimulus while requiring less time to achieve a target caloric expenditure. Thus, exercise intensity might be an important consideration in the tailoring of exercise prescription to address the cardiometabolic comorbidities of SCI.

Should Heartbeats/Training Session Be Considered When Comparing the Cardiovascular Benefits of High-Intensity Interval Aerobic and Moderate-Intensity Continuous Training? A Critical Appraisal

The prescription of physical training as a therapeutic measure in the treatment and control of chronic degenerative diseases, mainly cardiovascular disease and metabolic disease, is an increasingly used clinical approach, often preceding the pharmacological prescription. Despite the advances in exercise physiology and cardio functional performance in recent decades, the main challenge is to identify the most appropriate modality, intensity, and training volume for each pathophysiological situation. In this case, the superiority of high-intensity interval training (HIIT) over moderate-intensity continuous training (MICT) has been questioned, since many studies have shown similar results in the different physiological parameters evaluated, especially regarding cardiorespiratory fitness, cardiovascular autonomic control, and cardiac morpho functionality. The cause of conflicting results observed by different studies may be related to standardization, application, and comparison of the two protocols. HIIT would have a higher number of heartbeats compared to MICT, when maintaining high heart rate is disregarded. In this since, our hypothesis for the greatest gains in cardiorespiratory fitness and in the autonomic and cardiovascular adaptations promoted by HIIT is based on the higher volume of training performed as a function of the higher number of heartbeats per unit of time, since the intermittence was calculated based on a percentage of maximum heart rate or reserve heart rate. Nevertheless, the intermittency between the established heart rate percentages is not necessarily accompanied by the intermittent heart rate. Therefore, considering and matching the number of heartbeats performed per training session in both models seems to be a more appropriate way to compare the two training protocols.

Characterizing the Heart Rate Response to the 4 × 4 Interval Exercise Protocol

High intensity interval training is frequently implemented using the 4 × 4 protocol where four 4-min bouts are performed at heart rate (HR) between 85 and 95% HR max. This study identified the HR and power output response to the 4 × 4 protocol in 39 active men and women (age and VO₂ max = 26.0 ± 6.1 years and 37.0 ± 5.4 mL/kg/min). Initially, participants completed incremental cycling to assess VO₂ max, HR max, and peak power output (PPO). They subsequently completed the 4 × 4 protocol, during which HR and power output were monitored. Data showed that 12.9 ± 0.4 min of 16 min were spent between 85 and 95% HR max, with time spent significantly lower in interval 1 (2.7 ± 0.6 min) versus intervals 2–4 (3.4 ± 0.4 min, 3.4 ± 0.3 min, and 3.5 ± 0.3 min, d = 2.4–2.7). Power output was highest in interval 1 (75% PPO) and significantly declined in intervals 2–4 (63 to 54% PPO, d = 0.7–1.0). To enhance time spent between 85 and 95% HR max for persons with higher fitness, we recommend immediate allocation of supramaximal intensities in interval one.

Exercise Interventions in Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis

Background: Polycystic ovary syndrome (PCOS) is a common and complex endocrinopathy with reproductive and metabolic manifestations. Exercise training has consistently been found to result in improved clinical outcomes in women with PCOS, but shortfalls with exercise prescription are evident. The aim of this systematic review and meta-analysis was to identify exercise intervention characteristics that provide favourable outcomes in women with PCOS.

Methods: A systematic review of published literature was conducted using EBSCOhost and Ovid Medline up to May 2019. The review adheres to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines as per our PROSPERO protocol (CRD42018088367). Randomised controlled trials, non-randomised controlled trials, and uncontrolled trials that evaluated an exercise intervention of at least moderate intensity in women with PCOS were included. Meta-analyses were performed using general linear mixed modelling and Bayesian inferences about effect magnitudes.

Results: Thirty-three articles were identified for systematic review of which 19 were meta-analysed. Intervention duration ranged from 6 to 26 weeks. A total number of 777 women were included in the meta-analysis. The meta-analysis found that improvements in health outcomes are more dependent on exercise intensity rather than dose. Fixed effects analysis reported a moderate increase in VO_2peak (24.2%; 90% CL, 18.5–30.1), and small reductions in HOMA-IR (−36.2%; 90% CL, −55.3 to −9.0), and waist circumference (−4.2%; 90% CL −6.0 to −2.3) as a result of vigorous intensity exercise. These results are confirmed in the predicted analysis which reported the greatest improvements in VO_2peak, BMI, and waist circumference after vigorous intensity exercise alone or when combined with diet, particularly for women with clinically adverse baseline values.

Conclusions: Exercise training in the management of PCOS is becoming more common. Results from our analysis support the use of exercise and suggest that vigorous intensity exercise may have the greatest impact on cardiorespiratory fitness, body composition, and insulin resistance. Our results indicate that, a minimum of 120 min of vigorous intensity per week is needed to provide favourable health outcomes for women with PCOS with studies of longer duration required to evaluate outcomes with sustained exercise.

High INtensity Interval Training In pATiEnts with intermittent claudication (INITIATE): protocol for a multicentre, proof-of-concept, prospective interventional study

INTRODUCTION

The first-line recommended treatment for patients with intermittent claudication (IC) is a supervised exercise programme (SEP), which includes a minimum of 2-hours of exercise per week over a 12-week period. However, provision, uptake and adherence rates for these SEP programmes are poor, with time constraints cited as a common participant barrier. High-intensity interval training (HIIT) is more time-efficient and therefore has the potential to overcome this barrier. However, evidence is lacking for the role of HIIT in those with IC. This proof-of-concept study aims to consider the safety, feasibility, tolerability and acceptability of a HIIT programme for patients with IC.

METHODS AND ANALYSIS

This multicentre, single-group, prospective, interventional feasibility study will recruit 40 patients with IC, who will complete 6 weeks of HIIT, 3 times a week. HIIT will involve a supervised programme of 10×1 min high-intensity cycling intervals at 85%-90% peak power output (PPO), interspaced with 10×1 min low intensity intervals at 20%-25% PPO. PPO will be determined from a baseline cardiopulmonary exercise test (CPET) and it is intended that patients will achieve ≥85% of maximum heart rate from CPET, by the end of the second HIIT interval. Primary outcome measures are safety (occurrence of adverse events directly related to the study), programme feasibility (including participant eligibility, recruitment and completion rates) and HIIT tolerability (ability to achieve and maintain the required intensity). Secondary outcomes include patient acceptability, walking distance, CPET cardiorespiratory fitness measures and quality of life outcomes.

ETHICS AND DISSEMINATION

Ethical approval was obtained via a local National Health Service research ethics committee (Bradford Leeds - 18/YH/0112) and recruitment began in August 2019 and will be completed in October 2020. Results will be published in peer-reviewed journals and presented at international conferences and are expected to inform a future pilot randomised controlled trial of HIIT versus usual-care SEPs.

TRIAL REGISTRATION NUMBER

NCT04042311; Pre-results.

High-intensity interval training for heart failure with preserved ejection fraction: A protocol for systematic review and meta-analysis

BACKGROUND

The benefits of high-intensity interval training (HIIT) are well-known, there is insufficient evidence about the effects of HIIT on heart failure with preserved ejection fraction (HFpEF).

METHOD

Multiple databases include MEDLINE, PubMed, EMBASE, CINAHL, Web of Science, PEDro, Cochrane Library, and Google Scholar are used to search for randomized controlled trials investigating the effects of HIIT on HFpEF. All related articles published with the English language with no time limitation will be included. Two reviews independently conducted the selection, data extraction, and quality assessment. The primary outcome is exercise capacity. The secondary outcomes include quality of life (QoL), blood pressure (BP), ventricular function, and left ventricular diastolic function, symptom improvement, endothelial function, and arterial stiffness. Data analysis is performed with Review Manager Software (Version 5.3).

RESULT

This systematic review and meta-analysis aim to evaluate the efficacy of HIIT on HFpEF, its outcome will provide reliable evidence for future studies.

CONCLUSION

The findings of this study will be published in a related peer-reviewed journal.

REGISTRATION NUMBER

INPLASY202050097.

Exercise Time and Intensity: How Much Is Too Much?

The growing prevalence and popularity of interval training necessitate additional guidelines in regard to maximal levels of time and intensity.

PURPOSE

To correlate salivary hormones and time in varying heart-rate (HR) zones. The hypothesis was that chronic exercise durations >9% of total exercise time in the >90% maximum HR zone would lead to decreased variation in salivary cortisol concentration after exercise in a 2-bout high-intensity protocol compared with less or more time in this zone.

METHODS

A total of 35 healthy adults who regularly exercised for an average of 8 hours per week recorded their HR during every training session for 3 weeks. Later, they completed an experimental day composed of two 30-minute high-intensity interval sessions separated by 4 hours of nonactive recovery. The authors collected saliva samples before, immediately following, and 30 minutes after each exercise session to assess changes in cortisol concentrations.

RESULTS

There was a correlation between weekly time training at an intensity >90% maximum HR and the variables associated with overtraining. Salivary cortisol concentration fluctuated less in the participants who exercised in this extreme zone for >40 minutes per week (P < .001).

CONCLUSION

Based on the current study data, for individuals who regularly exercise, 4% to 9% total training time above 90% maximum HR is the ideal duration to maximize fitness and minimize symptoms related to overreaching.

The feasibility of implementing high-intensity interval training in cardiac rehabilitation settings: a retrospective analysis

Background

Cardiovascular disease is the leading cause of death worldwide. Notwithstanding the well-known benefits of cardiac rehabilitation (CR), adherence to CR remains low, particularly in women. High-intensity interval training (HIIT) has received specific attention as an emerging exercise-training paradigm that addresses frequently cited barriers to CR (i.e. lack of motivation/enjoyment and time, perceiving exercise regime as tiring/boring) and improves cardiovascular risk factors. Previous studies have examined the safety of HIIT in CR; there is little evidence on the feasibility of HIIT in CR. The aims of this study were to evaluate the feasibility of HIIT within a CR setting and examine the sex differences regarding the feasibility of such programming.

Methods

Patients attended an on-site HIIT CR program (10-min warm-up, 25 min of interspersed high-intensity [HI - 4 min at 85–95% HRpeak] and lower intensity [LO - 3 min at 60–70% HRpeak] intervals, 10-min cool-down) twice weekly for 10 weeks. Heart rate (HR) and the Borg rating of perceived exertion (RPE) scale (6–20 points) were recorded at each session. Feasibility was assessed by: [1] attendance and compliance: the number of sessions attended and the compliance to the prescribed HI and LO HR ranges; [2] the patient experience: patients’ perceived effort, program difficulty, if the program was challenging and satisfying; and, [3] safety. Descriptive statistics were used to report the means and their variations. Mann-Whitney U tests and Chi-square analyses were performed to examine sex-differences.

Results

A total of 151 patients (33% women, 57.5 ± 9.1 years) attended the HIIT program and completed 16 ± 5 classes with a low attrition rate (11.3%). Most patients met or exceeded the prescribed target HR for the HI (80%) and LO (84%) intervals, respectively. Patients reported a “somewhat hard” RPE for HI (14 ± 2 points) and “very light” for LO (10 ± 2 points) intervals. All patients were satisfied with the program and found it challenging. Most patients found HIIT to be difficult (7 ± 2 points, scale range 0–10 points), yet safe (97%). Three vasovagal episodes occurred and more women dropped-out of the program than men (p < 0.01).

Conclusions

HIIT is a feasible, safe and well-received exercise paradigm in a CR setting.

Acute High-Intensity Interval Exercise Improves Inhibitory Control Among Young Adult Males With Obesity

Objective

The aim of the present study was to examine the influence of acute high-intensity interval exercise (HIIE) on neural and behavioral measures of inhibitory control in young male adults with obesity.

Design

The present study employed a within-subjects design.

Methods

Sixteen male adults with obesity [body mass index (BMI) > 28 kg/m²] were recruited. Reaction time and response accuracy of the Flanker task as well as P3 and late positive potential (LPP) components of the event-related potential (ERP) were measured following HIIE and a sedentary control, in counterbalanced order. The HIIE session consisted of 30 min of stationary cycle exercise (5-min warm-up, 20-min HIIE, and a 5-min cool-down), whereas the control condition consisted of a time and attention-matched sedentary resting session.

Results

Faster response times were observed following HIIE regardless of Flanker task condition. Faster and more accurate responses were also observed for congruent relative to incongruent conditions across both sessions. Relative to the neuroelectric data, acute HIIE resulted in increased LPP amplitude but did not affect P3 amplitude.

Conclusion

Collectively, a single bout of HIIE has a general beneficial effect on basic information processing and inhibitory control among young adult males with obesity. Acute HIIE was found to impact LPP amplitude, but not the P3, which may suggest a modulation in the ability to successfully maintain attention and filter irrelevant information to achieve successful cognitive inhibition. Future research is warranted to extend these findings to a larger sample size that includes both genders, other cognitive functions, and a comparison of different modes of exercise.

Effect of high-intensity training on peak oxygen uptake and muscular strength after lung transplantation: A randomized controlled trial

BACKGROUND

Peak oxygen uptake (VO_2peak) remains low after lung transplantation (LTx). We evaluated the effect of high-intensity interval training (HIIT) on VO_2peak, muscular strength, health-related quality of life (HRQOL), pulmonary function, and physical function after LTx.

METHODS

In this randomized controlled trial, 54 participants were enrolled from 6 to 60 months after LTx. The HIIT group (n = 25) followed a supervised HIIT program, consisting of endurance and strength trainings 3 times a week for 20 weeks. The control group (n = 29) received usual care. The primary outcome was a change in VO_2peak measured by cardiopulmonary exercise testing. The secondary outcomes were changes in 1-repetition maximum (1RM) for arm press and leg press, HRQOL (36-Item Short-Form Health Survey [SF-36]), pulmonary function (forced expiratory volume in 1 sec, diffusing capacity of the lungs for carbon monoxide), and physical function (1RM in handgrip, 15-sec stair run, and 30-sec chair stand).

RESULTS

A total of 46 participants completed the study, including 23 of 25 in the intervention group. For the primary outcome, the intention-to-treat analysis revealed a non-significant between-group difference for change in VO_2peak of 0.7 ml/(kg.min) (95% CI = ‒0.3, 1.8) (p = 0.17). The between-group differences for 1RM arm press and leg press and mental aspect of SF-36 were 4.9 kg (95% CI = ‒0.1, 9.9) (p = 0.05), 11.6 kg (95% CI = 0.1, 23.0) (p < 0.05), and 5.7 kg (95% CI = 0.9, 10.4) (p = 0.02), respectively. There were no between-group differences in pulmonary function or physical function. When excluding participants with an attendance of <70% (n = 16), the between-group difference for VO_2peak was 1.2 ml/(kg.min) (95% CI = 0.1, 2.4) (p = 0.032).

CONCLUSIONS

HIIT improved muscular strength and HRQOL but did not improve VO_2peak more than usual care after LTx. However, with acceptable adherence, HIIT appears to have beneficial effects on VO_2peak.

Hemodynamics in young athletes following high-intensity interval or moderate-intensity continuous training

BACKGROUND

The present study aimed to investigate the effects of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on blood pressure (BP) and parameters of arterial stiffness in young athletes.

METHODS

Seventeen rowers (aged 15±1.3 years) were randomized into an intervention group (IG, N.=10) and the control group (CG, N.=7). During an 8-week intervention period, the IG completed a HIIT on the rowing ergometer twice-weekly (2×4×2 min at ≈95% of maximum heart rate [HR<inf>max</inf>], 60 s rest) in addition to the regular rowing training (3×/week MICT 70-90 min, ≈70% HR<inf>max</inf>). The CG completed the regular normal rowing training and, instead of the HIIT units, two additional MICT units (70-90 min, ≈70% HR<inf>max</inf>). Before and after the intervention period, hemodynamic parameters were recorded non-invasively in both groups.

RESULTS

After the intervention period, there was a significant decrease in peripheral systolic (P=0.01) and diastolic (P=0.05) BP, as well as in central systolic (P=0.05) and diastolic BP (P=0.03) in the IG. Furthermore, pulse wave velocity (PWV) (P=0.05) was significantly reduced. Analysis of intervention effects revealed significant between-group differences in central diastolic BP (P=0.05), in augmentation pressure (P=0.02), and in augmentation index (P=0.006) favoring IG. The CG showed no significant changes in the respected parameters throughout the intervention.

CONCLUSIONS

Already in adolescent athletes, a HIIT intervention has beneficial effects on peripheral and central BP as well as on PWV, augmentation pressure, and augmentation index.

Exercise Intensity Matters in Chronic Nonspecific Low Back Pain Rehabilitation

INTRODUCTION

Exercise therapy (ET) is advocated as a treatment for chronic nonspecific low back pain (CNSLBP). However, therapy effect sizes remain low. In other chronic disorders, training at higher intensity has resulted in greater improvements on both general health related and disease specific outcomes compared to lower-intensity ET. Possibly, high-intensity training also improves effect sizes in CNSLBP.

OBJECTIVE

To compare the effects of a high-intensity ET program with a similar moderate-intensity ET program on disability, pain, function, exercise capacity, and abdominal/back muscle strength in persons with CNSLBP.

METHODS

In a randomized controlled trial, persons with CNSLBP performed a 12-wk ET program (24 sessions, 1.5 h per session, twice per week) at high-intensity training (HIT) or moderate-intensity training (MIT). Questionnaires to assess disability (Modified Oswestry Index [MODI]), pain intensity (Numeric Pain Rating Scale), and function (Patient Specific Functioning Scale), a cardiopulmonary exercise test to assess exercise capacity (V˙O2max, cycling time), and a maximum isometric muscle strength test to assess abdominal/back muscle strength (maximum muscle torque) were administered at baseline and after the training program.

RESULTS

Thirty-eight participants (HIT: n = 19, MIT: n = 19) were included (mean age, 44.1 yr, SD = 9.8, 12 males). Groups did not differ at baseline. Between group differences (P < 0.01) in favor of HIT were found for MODI, V˙O2max, and cycling time. Within group improvements (P < 0.01) were found in both groups on MODI (HIT:-64%, MIT:-33%), Numeric Pain Rating Scale (HIT, -56%; MIT, -39%), Patient-Specific Functioning Scale (HIT:+37%, MIT:+39%), V˙O2max (HIT:+14, MIT:+4%), cycling time (HIT:+18%, MIT:+13%), and back muscle strength (HIT:+10%, MIT:+14%).

CONCLUSIONS

High-intensity training proved to be a feasible, well tolerated, and effective therapy modality in CNSLBP. Moreover, it shows greater improvements on disability and exercise capacity than a similar ET performed at moderate intensity.

High Intensity Resistance Exercise Training vs. High Intensity (Endurance) Interval Training to Fight Cardiometabolic Risk Factors in Overweight Men 30-50 Years Old

Cardiovascular and cardiometabolic diseases are leading causes of death worldwide. Exercise favorably affects this problem, however only few invest (enough) time to favorably influence cardiometabolic risk-factors and cardiac morphology/performance. Time-effective, high-intensity, low-volume exercise protocols might increase people's commitment to exercise. To date, most research has focused on high-intensity interval training (HIIT), the endurance type of HIT, while corresponding HIT-resistance training protocols (HIT-RT) are rarely evaluated. In this study we compared the effect of HIIT vs. HIT-RT, predominately on cardiometabolic and cardiac parameters in untrained, overweight-obese, middle-aged men. Eligible, untrained men aged 30–50 years old in full-time employment were extracted from two joint exercise studies that randomly assigned participants to a HIIT, HIT-RT or corresponding control group. HIIT predominately consisted of interval training 90 s−12 min, (2–4 sessions/week), HIT-RT (2–3 sessions/week) was applied as a single set resistance training to muscular failure. Core intervention length of both protocols was 16 weeks. Main inclusion criteria were overweight-obese status (BMI 25–35 kg/m²) and full employment (occupational working time: ≥38.5 h/week). Primary study-endpoint was the Metabolic Syndrome (MetS) Z-Score, secondary study-endpoints were ventricular stroke volume index (SVI) and myocardial mass index (MMI) as determined by Magnetic Resonance Imaging. The Intention to treat (ITT) principle was applied to analyze the summarized data set. Twenty-seven eligible men of the HIT-RT and 30 men of the HIIT group were included in the ITT. Both interventions significantly (p < 0.001) improve the MetS Z-Score, however the effect of HIIT was superior (p = 0.049). In parallel, HIT-RT and HIIT significantly affect SVI and MMI, with the effect of HIIT being much more pronounced (p < 0.001). Although HIIT endurance exercise was superior in favorably affecting cardiometabolic risk and particularly cardiac performance, both exercise methods positively affect cardiometabolic risk factors in this overweight to obese, middle-aged cohort of males with low time resources. Thus, the main practical application of our finding might be that in general overweight-obese people can freely choose their preferred exercise type (HIIT-END or HIT-RT) to improve their cardiometabolic health, while investing an amount of time that should be feasible for everybody.

Trial Registrations: NCT01406730, NCT01766791.

Semisupervised Physical Exercise and Lifestyle Counseling in Cardiometabolic Risk Management in Sedentary Adults: Controlled Randomized Trial (BELLUGAT)

BACKGROUND

The purpose of this study was to evaluate the feasibility and effectiveness of a high-intensity semisupervised exercise program alongside lifestyle counseling as an intervention for managing cardiometabolic risk in sedentary adults.

METHODS

A 40-week 3-arm randomized controlled clinical trial (16-wk intervention and 24-wk follow-up) was used. Seventy-five sedentary adults (34-55 y) with at least 1 cardiometabolic risk factor were randomized into one of the following arms: (1) aerobic interval training (AIT) plus lifestyle counseling (n = 25), (2) low- to moderate-intensity continuous training plus lifestyle counseling (traditional continuous training, TCT) (n = 27), or (3) lifestyle counseling alone (COU) (n = 23). Metabolic syndrome severity scores, accelerometer-based physical activity, and self-reported dietary habits were assessed at baseline, after the intervention, and at follow-up.

RESULTS

AIT was well accepted with high enjoyment scores. All groups showed similar improvements in metabolic syndrome severity scores (standardized effect size = 0.46) and dietary habits (standardized effect size = 0.30). Moderate to vigorous physical activity increased in all study groups, with the number of responders higher in AIT and TCT groups (50%) than in COU group (21%). Both AIT and TCT had a greater impact on sedentary behavior than COU (63.5% vs 30.4% responders).

CONCLUSIONS

AIT appears to be a feasible and effective strategy in sedentary individuals with cardiometabolic risk factors. AIT could be included in intervention programs tackling unhealthy lifestyles.

The Effects of Concurrent Training Combining Both Resistance Exercise and High-Intensity Interval Training or Moderate-Intensity Continuous Training on Metabolic Syndrome

To date, there are several knowledge gaps on how to properly prescribe concurrent training to achieve the best dose-response, especially regarding the optimal intensity or volume of the aerobic component. Thus, the objective of this study is to analyze the effects of different aerobic exercise modes and intensities [i.e. aerobic high-intensity interval training (HIIT) versus moderate-intensity continuous aerobic training (MICT) combined with a resistance training (RT) program] on metabolic outcomes in participants with metabolic syndrome (MetS). Thirty-nine men and women (67.0 ± 6.7 years) volunteered to a 12-weeks exercise intervention (3 week^–1, 50 min/session) and were randomly assigned to one of three groups: (a) RT plus MICT (RT+MICT) (2 males; 11 females); (b) RT plus HIIT (RT+HIIT) (4 males; 9 females); and (c) control group (CON) – without formal exercise (4 males; 9 females). Intensity was established between 60 and 70% of maximum heart rate (HRmax) in RT+MICT and ranged from 55–65% to 80–90% HRmax in the RT+HIIT group. Dependent outcomes included morphological, metabolic and hemodynamic variables. Both training groups improved waist circumference (RT+MICT: P = 0.019; RT+HIIT: P = 0.003), but not body weight, fat mass or fat-free mass (P ≥ 0.114). RT+HIIT group improved fasting glucose (P = 0.014), low density lipoprotein [LDL (P = 0.022)], insulin (P = 0.034) and homeostatic model assessment (P = 0.028). RT+MICT group reduced triglycerides (P = 0.053). Both exercise interventions did not change high sensitivity C-reactive protein, glycated hemoglobin, high density lipoprotein and total cholesterol, systolic, diastolic or mean arterial blood pressure (P ≥ 0.05). The CON group reduced the LDL (P = 0.031). This trial suggests that short-term exercise mode and intensity may differently impact the metabolic profile of individuals with MetS. Further, our data suggests that both concurrent trainings promote important cardiometabolic gains, particularly in the RT+HIIT. Nonetheless, due to the small-to-moderate effect size and the short-term intervention length, our data suggests that the intervention length also has an important modulating role in these benefits in older adults with MetS. Therefore, more research is needed to confirm our results using longer exercise interventions and larger groups.

HIITing the brain with exercise: mechanisms, consequences and practical recommendations

The increasing number of older adults has seen a corresponding growth in those affected by neurovascular diseases, including stroke and dementia. Since cures are currently unavailable, major efforts in improving brain health need to focus on prevention, with emphasis on modifiable risk factors such as promoting physical activity. Moderate-intensity continuous training (MICT) paradigms have been shown to confer vascular benefits translating into improved musculoskeletal, cardiopulmonary and cerebrovascular function. However, the time commitment associated with MICT is a potential barrier to participation, and high-intensity interval training (HIIT) has since emerged as a more time-efficient mode of exercise that can promote similar if not indeed superior improvements in cardiorespiratory fitness for a given training volume and further promote vascular adaptation. However, randomised controlled trials (RCTs) investigating the impact of HIIT on the brain are surprisingly limited. The present review outlines how the HIIT paradigm has evolved from a historical perspective and describes the established physiological changes including its mechanistic bases. Given the dearth of RCTs, the vascular benefits of MICT are discussed with a focus on the translational neuroprotective benefits including their mechanistic bases that could be further potentiated through HIIT. Safety implications are highlighted and components of an optimal HIIT intervention are discussed including practical recommendations. Finally, statistical effect sizes have been calculated to allow prospective research to be appropriately powered and optimise the potential for detecting treatment effects. Future RCTs that focus on the potential clinical benefits of HIIT are encouraged given the prevalence of cognitive decline in an ever-ageing population.

Effect of high-intensity interval training and continuous endurance training on peak oxygen uptake among seniors aged 65 or older: A meta-analysis of randomized controlled trials

BACKGROUND

Ageing is intrinsically associated with a progressive decline in cardiorespiratory fitness (CRF) as measured by peak oxygen uptake (VO_2peak ). Improving CRF through physical activity contribute to better and healthy ageing. High-intensity interval training (HIIT) is a potent method of improving CRF among seniors, yet comparisons between this type of training and traditional endurance training (ET) are equivocal especially among older adults.

PURPOSE

To analyse the effects of HIIT and ET on the VO_2peak of seniors aged 65 years or older when compared with controls and also when the two types of training were compared with one another.

METHODS

A comprehensive, systematic database search for manuscripts was performed in Embase, Medline, PubMed Central, ScienceDirect, Scopus and Web of Science using key words. Two reviewers independently assessed interventional studies for potential inclusion. Fifteen randomized controlled trials (RCTs) were included totalling 480 seniors aged 65 years or over. Across the trials, no high risk of bias was measured.

RESULTS

In pooled analysis of the RCTs, the VO_2peak was significantly higher after ET sessions compared with controls (mean difference-MD = 1.35; 95% confidence interval-CI: 0.73-1.96). Furthermore, VO_2peak was found significantly higher not only when compared HIIT with controls (MD = 4.61; 95% CI: 3.21-6.01), but also when compared HIIT with ET (MD = 3.76; 95% CI: 2.96-4.56).

CONCLUSION

High-intensity interval training and ET both elicit large improvements in the VO_2peak of older adults aged 65 or over. When compared with ET, the gain in VO_2peak was greater following HIIT. Nevertheless, further RCTs are therefore needed to confirm our results in senior's population.

Effect of different exercise training intensities on musculoskeletal and neuropathic pain in inactive individuals with type 2 diabetes - Preliminary randomised controlled trial

AIMS

People with type 2 diabetes (T2D) have a greater prevalence of musculoskeletal and neuropathic pain. This exploratory analysis investigated whether exercise of different intensities leads to changes in self-reported musculoskeletal pain or symptoms of diabetic neuropathy in inactive individuals with type 2 diabetes.

METHODS

Thirty-two inactive adults with T2D (59% male, mean age 58.7 ± 9.1yrs, median HbA_1c 7.8%) were randomised to usual care (CON), supervised combined aerobic and resistance moderate-intensity continuous training (C-MICT), or supervised combined high-intensity interval training (C-HIIT). At baseline and 8-weeks, musculoskeletal and neuropathic pain were evaluated using a modified Nordic Musculoskeletal Questionnaire and the Neuropathy Total Symptom Score-6 respectively. Quantitative sensory testing was used to determine thermal, mechanical and vibration detection thresholds, as well as pain pressure thresholds. Adverse events were recorded throughout the intervention.

RESULTS

Compared to CON, reduction in musculoskeletal pain intensity was significantly greater for C-HIIT (MD -5.4, 95% CI [-10.6 to -0.2], p = 0.04) and non-significantly greater for C-MICT (MD -5.9 [-12.4 to 0.7], p = 0.08). Changes in neuropathy symptoms were not different between C-HIIT and CON (MD 1.0 [-0.9 to 2.8], p = 0.31), or C-MICT and CON (MD 0.2 [-3.1 to 3.6], p = 0.89). No differences in sensory function were observed between groups. Similar rates of adverse events were seen in both exercise interventions (19 C-HIIT; 17 C-MICT), all but one of which were mild.

CONCLUSIONS

Preliminary data suggests 8-weeks of high-intensity combined aerobic and resistance exercise may be safely prescribed for inactive individuals with T2D and may reduce musculoskeletal pain but not neuropathic symptoms.

TRIAL REGISTRATION

ACTRN12615000475549.

Counteracting Physical Inactivity during the COVID-19 Pandemic: Evidence-Based Recommendations for Home-Based Exercise

To reduce transmission of the coronavirus, from its initial outbreak in 2019 up to now, various safety measures have been enacted worldwide by the authorities that have likely led to reduced physical activity levels in the general population. This short communication aims to briefly outline the deteriorative consequences of physical inactivity on parameters of physical fitness and ultimately to highlight associated increases of cardiovascular disease risk and mortality. Finally, evidence-based practical recommendations for exercise that can be performed at home are introduced, to help avoid physical inactivity and therefore maintain or achieve good physical health.

High-Intensity Interval Training Is Feasible in Women at High Risk for Breast Cancer

Purpose

This trial aimed to demonstrate the feasibility of high-intensity interval training (HIIT) in postmenopausal, overweight/obese women at high risk of invasive breast cancer and to explore HIIT on changes in cardiorespiratory fitness (CRF), body weight, and body mass index (BMI) compared with moderate-intensity continuous training (MICT) and usual care (UC).

Methods

Forty-four women were randomized to HIIT, MICT, or UC for a 12-wk, thrice weekly, supervised exercise intervention. HIIT included a 5-min warm-up at 50%–70% HR_peak, four cycles of 4 min at 90%–100% HR_peak, followed by 3 min at 50%–70% HR_peak. MICT consisted of 41 min at 60%–70% HR_peak. Feasibility was assessed by consent, adherence, compliance, and retention rates. CRF, body weight, and BMI were measured at baseline and end of study. Repeated-measures linear mixed models were used to assess within- and between-group differences.

Results

Average age was 63.9 ± 8.8 yr. BMI was 30.9 ± 5.7 kg·m⁻². Participants completed 90% and 89% of HIIT and MICT workouts, respectively, with 100% compliance to the exercise prescriptions. No serious adverse events were reported. Compared with MICT and UC, HIIT exhibited improvements in change in treadmill time (101 s greater than MICT, and 125 s greater than UC, respectively, P < 0.001). Compared with UC, HIIT exhibited improvement in changes in absolute and relative V˙O_2peak (a 0.15-L·min⁻¹ increase, P = 0.005, and a 2.3-mL·kg⁻¹⋅min⁻¹ increase, P = 0.004). There were no significant differences between groups for body weight or BMI (P > 0.05).

Conclusions

HIIT is feasible, safe, and seems to promote greater improvements in CRF compared with MICT and UC in women at high risk for breast cancer.

Optimizing the Interaction of Exercise Volume and Metformin to Induce a Clinically Significant Reduction in Metabolic Syndrome Severity: A Randomised Trial

Insulin resistance is a central mediating factor of the metabolic syndrome (MetS), with exercise training and metformin proven antidotes to insulin resistance. However, when the two therapies are combined there is conflicting data regarding whether metformin blunts or improves exercise training-induced adaptations. The volume of exercise (duration, intensity, and frequency) on the interaction of exercise training and metformin has yet to be investigated. The aim of this study is therefore to explore the impact of a combination of different exercise volumes and metformin on MetS severity. This is a secondary analysis of data from one of the sites of the ‘Exercise in Prevention of Metabolic Syndrome’ (EX-MET) study. Ninety-nine adults with MetS were randomized into a 16-week exercise program completing either: (i) moderate-intensity continuous training (MICT) at 60–70% of peak heart rate (HRpeak) for 30 min/session (n = 34, 150 min/week); (ii) high-volume high-intensity interval training (HIIT) consisting of 4 × 4 min bouts at 85–95% HRpeak, interspersed with 3 min of active recovery at 50–70% HRpeak (n = 34, 38 min/session, 114 min/week); or (iii) low volume HIIT, 1 × 4 min bout of HIIT at 85–95% HRpeak (n = 31, 17 min/session, 51 min/week). Metformin intake was monitored and recorded throughout the trial. MetS severity was calculated as z-scores derived from MetS risk factors assessed at pre- and post-intervention. Sixty-five participants had complete pre- and post-intervention data for MetS z-score, of which 18 participants (28%) were taking metformin. Over the 16-week intervention, a similar proportion of participants clinically improved MetS severity (Δ ≥ −0.87) with metformin (8/18, 44%) or without metformin (23/47, 49%) (p = 0.75). While there were no between-group differences (p = 0.24), in those who did not take metformin low-volume HIIT had more likely responders (10/15, 67%) compared to MICT (6/16, 38%) and high-volume HIIT (7/16, 44%). In those taking metformin, there was a lower proportion of participants who clinically improved MetS severity following high-volume HIIT (1/6, 17%) compared to MICT (2/4, 50%) and low-volume HIIT (5/8, 63%), but with no between-group difference (p = 0.23). Moreover, in those who performed high-volume HIIT, there was a statistically significantly higher proportion (p = 0.03) of likely non-responders with improved MetS severity in participants taking metformin (4/6, 67%) compared to those not taking metformin (3/16, 19%). In individuals with MetS, the effect of high volume HIIT on MetS severity may be blunted in those taking metformin. These findings need to be confirmed in a larger study.