High-Intensity Interval Training and Cardiometabolic Health in the General Population: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Diet and physical activity interventions to improve cardiovascular disease risk factors in liver transplant recipients: Systematic review and meta-analysis

BACKGROUND AND AIMS

Cardiovascular disease, associated risk factors and obesity are prevalent after liver transplant and modifiable through lifestyle changes. Understanding what lifestyle interventions and their respective components are effective is essential for translation to clinical practice. We aimed to investigate the effects of diet and physical activity interventions on weight, body mass index and other cardiovascular disease risk factors in liver transplant recipients, and systematically describe the interventions.

METHODS

We systematically searched Embase, MEDLINE, Psycho Info, CINAHL, Cochrane central register of controlled trials, PeDro, AMED, BNI, Web of Science, OpenGrey, ClinicalTrials.gov and the international clinical trials registry from inception to 31 May 2023. Search results were screened by two independent reviewers: randomised control trials with interventions that targeted diet and physical activity behaviours in liver transplant recipients were considered eligible. Two independent reviewers extracted and synthesised data for study, participant and intervention details and results. We used the Revised Cochrane Risk of Bias Tool for Randomised Trials to assess risk of bias for outcomes and the GRADE approach to rate the quality of the body of evidence. When two or more studies reported findings for an outcome, we pooled data using random-effects meta-analysis.

RESULTS

Six studies were included, reporting three physical activity and three combined diet and physical activity interventions. Participants were 2 months-4 years post-transplant. Interventions lasted 12 weeks-10 months and were delivered remotely and/or in-person, most commonly delivered to individual participants by health care or sports professionals. Five studies described individual tailoring, e.g. exercise intensity. Adherence to interventions ranged from 51% to 94%. No studies reported fidelity. Intervention components were not consistently reported. In meta-analysis, diet and physical activity interventions did not significantly reduce weight or body mass index compared to control groups, however no studies targeted participants with obesity. Diet and physical activity interventions reduced percentage body fat and triglycerides compared to control groups but did not reduce total cholesterol or increase activity. The GRADE quality of evidence was low or very low.

CONCLUSION

Diet and physical activity interventions reduced percentage body fat and triglycerides in liver transplant recipients. Further good quality research is needed to evaluate their effect on other cardiovascular disease risk factors, including weight and BMI. Interventions need to be better described and evaluated to improve evidence base and inform patient care.

Longitudinal Associations between 24-h Movement Behaviors and Cardiometabolic Biomarkers: A Natural Experiment over Retirement

INTRODUCTION

Physical activity, sedentary behavior, and sleep, that is, 24-h movement behaviors, often change in the transition from work to retirement, which may affect cardiometabolic health. This study investigates the longitudinal associations between changes in 24-h movement behaviors and cardiometabolic biomarkers during the retirement transition.

METHODS

Retiring public sector workers ( n = 212; mean (SD) age, 63.5 (1.1) yr) from the Finnish Retirement and Aging study used a thigh-worn Axivity accelerometer and filled out a diary to obtain data on daily time spent in sedentary behavior (SED), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA), and sleep before and after retirement (1 yr in-between). Cardiometabolic biomarkers, including LDL-cholesterol, HDL-cholesterol, total/HDL-cholesterol ratio, triglycerides, C-reactive protein, fasting glucose, and insulin, were measured. Associations between changes in 24-h movement behaviors and cardiometabolic biomarkers were analyzed using compositional robust regression and isotemporal substitution analysis.

RESULTS

Increasing LPA in relation to remaining behaviors was associated with an increase in HDL-cholesterol and decrease in total/HDL-cholesterol ratio ( P < 0.05 for both). For instance, reallocation of 30 min from sleep/SED to LPA was associated with an increase in HDL-cholesterol by 0.02 mmol·L -1 . Moreover, increasing MVPA in relation to remaining behaviors was associated with a decrease in triglycerides ( P = 0.02). Reallocation of 30 min from SED/sleep to MVPA was associated with 0.07-0.08 mmol·L -1 decrease in triglycerides. Findings related to LDL-cholesterol, C-reactive protein, fasting glucose, and insulin were less conclusive.

CONCLUSIONS

During the transition from work to retirement, increasing physical activity at the expense of passive behaviors was associated with a better lipid profile. Our findings suggest that life transitions like retirement could be utilized more as an optimal time window for promoting physical activity and health.

High-intensity interval training and cardiorespiratory fitness in adults: An umbrella review of systematic reviews and meta-analyses

BACKGROUND

High-intensity interval training (HIIT) is characterized by repeated bouts of relatively intense exercise interspersed with recovery periods. Previous studies have evaluated this exercise strategy with various population subgroups, regimens, and comparator groups, limiting the generalizability of findings. We performed a novel umbrella review to generate an up-to-date synthesis of the available evidence regarding the effect of HIIT on cardiorespiratory fitness (CRF) in adults as compared to non-exercise control and traditional continuous forms of exercise such as moderate-intensity continuous training (MICT).

METHODS

An umbrella review was conducted in accordance with the Preferred Reporting Items for Overviews of Reviews guideline. Seven databases (MEDLINE, EMBASE, Cochrane Database, CINAHL, Scopus, SPORTDiscus, and Web of Science) were searched until February 2024. Systematic reviews with meta-analyses comparing HIIT and active/non-active control conditions were included. Literature search, data extraction, and methodological quality assessment (AMSTAR-2) were conducted independently by two reviewers.

RESULTS

Twenty-four systematic reviews with meta-analyses, representing 429 primary studies and 12 967 unique participants, met the inclusion criteria. Most of the systematic reviews received moderate-to-critically low AMSTAR-2 scores. The data showed that HIIT, including the particularly intense variant "sprint interval training" (SIT), significantly increases CRF in adults compared to non-exercise control (standardized mean difference [SMD]: 0.28 to 4.31; weighted mean difference [WMD]: 3.25 to 5.5 mL/kg/min) and MICT (SMD: 0.18 to 0.99; WMD: 0.52 to 3.76 mL/kg/min). This effect was consistently observed across specific groups of individuals (e.g., apparently healthy adults, individuals with overweight/obesity, older adults, and high-level athletes) and HIIT modalities (e.g., low-volume HIIT, whole-body HIIT, home-based HIIT, aquatic HIIT, and short SIT).

CONCLUSION

Existing evidence from systematic reviews consistently supports the effect of HIIT on enhancing CRF in adults when compared to non-exercise control and MICT. Our findings offer a comprehensive basis that may potentially contribute to informing physical activity guidelines aimed at improving CRF in the general population.

Effect of high-intensity interval training in physiotherapy primary care for patients with inflammatory arthritis: the ExeHeart randomised controlled trial

OBJECTIVES

To assess the effect of high-intensity interval training (HIIT) delivered in physiotherapy primary care on the primary outcome of cardiorespiratory fitness (CRF) in patients with inflammatory arthritis (IA). Additionally, to explore the effects of HIIT on secondary outcomes, including cardiovascular disease (CVD) risk factors and disease activity.

METHODS

Single-blinded randomised controlled trial with 60 patients randomly assigned to either a control group receiving usual care or an exercise group receiving usual care and 12 weeks of individualised HIIT at 90%-95% peak heart rate. Outcomes were assessed at baseline, 3 months and 6 months post baseline and included CRF measured as peak oxygen uptake (VO2peak), classic CVD risk factors, disease activity, anthropometry and patient-reported physical activity, pain, fatigue, disease impact and exercise beliefs and self-efficacy.

RESULTS

Intention-to-treat analysis demonstrated a significant between-group difference in VO2peak at 3 months (2.5 mL/kg/min, 95% CI 0.9 to 4.0) and 6 months (2.6 mL/kg/min, 95% CI 0.8 to 4.3) in favour of the exercise group. A beneficial change in self-reported physical activity in favour of the exercise group was observed at 3 and 6 months. The HIIT intervention was well-tolerated with minimal adverse events and no apparent impact on disease activity. Differences in secondary outcomes related to CVD risk factors, disease impact, pain, fatigue and exercise beliefs and self-efficacy were generally small and non-significant.

CONCLUSION

After 12 weeks of supervised HIIT delivered in physiotherapy primary care, patients with IA demonstrated a favourable improvement in CRF, with sustained effects at 6-month follow-up.

TRIAL REGISTRATION NUMBER

NCT04922840.

Effects of High-Intensity Interval Training Using the 3/7 Resistance Training Method on Metabolic Stress in People with Heart Failure and Coronary Artery Disease: A Randomized Cross-Over Study

The 3/7 resistance training (RT) method involves performing sets with increasing numbers of repetitions, and shorter rest periods than the 3x9 method. Therefore, it could induce more metabolic stress in people with heart failure with reduced ejection fraction (HFrEF) or coronary artery disease (CAD). This randomized cross-over study tested this hypothesis. Eleven individuals with HFrEF and thirteen with CAD performed high-intensity interval training (HIIT) for 30 min, followed by 3x9 or 3/7 RT according to group allocation. pH, HCO3-, lactate, and growth hormone were measured at baseline, after HIIT, and after RT. pH and HCO3- decreased, and lactate increased after both RT methods. In the CAD group, lactate increased more (6.99 ± 2.37 vs. 9.20 ± 3.57 mmol/L, p = 0.025), pH tended to decrease more (7.29 ± 0.06 vs. 7.33 ± 0.04, p = 0.060), and HCO3- decreased more (18.6 ± 3.1 vs. 21.1 ± 2.5 mmol/L, p = 0.004) after 3/7 than 3x9 RT. In the HFrEF group, lactate, pH, and HCO3- concentrations did not differ between RT methods (all p > 0.248). RT did not increase growth hormone in either patient group. In conclusion, the 3/7 RT method induced more metabolic stress than the 3x9 method in people with CAD but not HFrEF.

A Perspective on High-Intensity Interval Training for Performance and Health

Interval training is a simple concept that refers to repeated bouts of relatively hard work interspersed with recovery periods of easier work or rest. The method has been used by high-level athletes for over a century to improve performance in endurance-type sports and events such as middle- and long-distance running. The concept of interval training to improve health, including in a rehabilitative context or when practiced by individuals who are relatively inactive or deconditioned, has also been advanced for decades. An important issue that affects the interpretation and application of interval training is the lack of standardized terminology. This particularly relates to the classification of intensity. There is no common definition of the term "high-intensity interval training" (HIIT) despite its widespread use. We contend that in a performance context, HIIT can be characterized as intermittent exercise bouts performed above the heavy-intensity domain. This categorization of HIIT is primarily encompassed by the severe-intensity domain. It is demarcated by indicators that principally include the critical power or critical speed, or other indices, including the second lactate threshold, maximal lactate steady state, or lactate turnpoint. In a health context, we contend that HIIT can be characterized as intermittent exercise bouts performed above moderate intensity. This categorization of HIIT is primarily encompassed by the classification of vigorous intensity. It is demarcated by various indicators related to perceived exertion, oxygen uptake, or heart rate as defined in authoritative public health and exercise prescription guidelines. A particularly intense variant of HIIT commonly termed "sprint interval training" can be distinguished as repeated bouts performed with near-maximal to "all out" effort. This characterization coincides with the highest intensity classification identified in training zone models or exercise prescription guidelines, including the extreme-intensity domain, anaerobic speed reserve, or near-maximal to maximal intensity classification. HIIT is considered an essential training component for the enhancement of athletic performance, but the optimal intensity distribution and specific HIIT prescription for endurance athletes is unclear. HIIT is also a viable method to improve cardiorespiratory fitness and other health-related indices in people who are insufficiently active, including those with cardiometabolic diseases. Research is needed to clarify responses to different HIIT strategies using robust study designs that employ best practices. We offer a perspective on the topic of HIIT for performance and health, including a conceptual framework that builds on the work of others and outlines how the method can be defined and operationalized within each context.

High-intensity interval training versus moderate-intensity continuous training on patient quality of life in cardiovascular disease: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on the quality of life (QOL) and mental health (MH) of patients with cardiovascular disease (CVDs). Web of Science, Medline, Embase, Cochrane (CENTRAL), CINAHL, China National Knowledge Infrastructure, Wanfang, and China Science and Technology Journal databases were searched from their date of establishment to July, 2023. A total of 5798 articles were screened, of which 25 were included according to the eligibility criteria. The weighted mean difference (WMD) and standardized mean difference (SMD) were used to analyze data from the same and different indicator categories, respectively. The fixed-effects model (FE) or random-effects model (RE) combined data based on the between-study heterogeneity. There were no statistically significant differences regarding QOL, physical component summary (PCS), mental component summary (MCS), and MH, including depression and anxiety levels, between the HIIT and MICT groups [SMD = 0.21, 95% confidence interval (CI)  - 0.18-0.61, Z = 1.06, P = 0.290; SMD = 0.10, 95% CI  - 0.03-0.23, Z = 1.52, P = 0.128; SMD = 0.07, 95% CI  - 0.05-0.20, Z = 1.13, P = 0.25; SMD = - 0.08, 95% CI  - 0.40-0.25, Z = - 0.46, P = 0.646; WMD = 0.14. 95% CI  - 0.56-0.84, Z = 0.39, P = 0.694, respectively]. HIIT significantly improved PCS in the coronary artery disease (CAD) population subgroup relative to MICT. HIIT was also significantly superior to MICT for physical role, vitality, and social function. We conclude that HIIT and MICT have similar effects on QOL and MH in patients with CVD, while HIIT is favorable for improving patients' self-perceived physiological functioning based on their status and social adjustment, and this effect is more significant in patients with CAD.