Low-volume high-intensity swim training is superior to high-volume low-intensity training in relation to insulin sensitivity and glucose control in inactive middle-aged women

Health Benefits of Different Sports: a Systematic Review and Meta-Analysis of Longitudinal and Intervention Studies Including 2.6 Million Adult Participants

BACKGROUND

Several reviews have examined the health benefits of participation in specific sports, such as baseball, cricket, cross-country skiing, cycling, downhill skiing, football, golf, judo, rugby, running and swimming. However, new primary studies on the topic have recently been published, and the respective meta-analytic evidence needs to be updated.

OBJECTIVES

To systematically review, summarise and appraise evidence on physical health benefits of participation in different recreational sports.

METHODS

Searches for journal articles were conducted in PubMed/MEDLINE, Scopus, SpoLit, SPORTDiscus, Sports Medicine & Education Index and Web of Science. We included longitudinal and intervention studies investigating physical health outcomes associated with participation in a given sport among generally healthy adults without disability.

RESULTS

A total of 136 papers from 76 studies conducted among 2.6 million participants were included in the review. Our meta-analyses of available evidence found that: (1) cycling reduces the risk of coronary heart disease by 16% (pooled hazard ratio [HR] = 0.84; 95% confidence interval [CI]: 0.80, 0.89), all-cause mortality by 21% (HR = 0.79; 95% CI: 0.73, 0.84), cancer mortality by 10% (HR = 0.90; 95% CI: 0.85, 0.96) and cardiovascular mortality by 20% (HR = 0.80; 95% CI: 0.74, 0.86); (2) football has favourable effects on body composition, blood lipids, fasting blood glucose, blood pressure, cardiovascular function at rest, cardiorespiratory fitness and bone strength (p < 0.050); (3) handball has favourable effects on body composition and cardiorespiratory fitness (p < 0.050); (4) running reduces the risk of all-cause mortality by 23% (HR = 0.77; 95% CI: 0.70, 0.85), cancer mortality by 20% (HR = 0.80; 95% CI: 0.72, 0.89) and cardiovascular mortality by 27% (HR = 0.73; 95% CI: 0.57, 0.94) and improves body composition, cardiovascular function at rest and cardiorespiratory fitness (p < 0.010); and (5) swimming reduces the risk of all-cause mortality by 24% (HR = 0.76; 95% CI: 0.63, 0.92) and improves body composition and blood lipids (p < 0.010).

CONCLUSIONS

A range of physical health benefits are associated with participation in recreational cycling, football, handball, running and swimming. More studies are needed to enable meta-analyses of health benefits of participation in other sports. PROSPERO registration number CRD42021234839.

Rates of compliance and adherence to high-intensity interval training: a systematic review and Meta-analyses

BACKGROUND

To determine rates of compliance (i.e., supervised intervention attendance) and adherence (i.e., unsupervised physical activity completion) to high-intensity interval training (HIIT) among insufficiently active adults and adults with a medical condition, and determine whether compliance and adherence rates were different between HIIT and moderate-intensity continuous training (MICT).

METHODS

Articles on adults in a HIIT intervention and who were either insufficiently active or had a medical condition were included. MEDLINE, EMBASE, PsychINFO, SPORTDiscus, CINAHL, and Web of Science were searched. Article screening and data extraction were completed by two independent reviewers. Risk of bias was assessed using RoB 2.0 or ROBINS-I. Meta-analyses were conducted to discern differences in compliance and adherence between HIIT vs. MICT. Sensitivity analyses, publication bias, sub-group analyses, and quality appraisal were conducted for each meta-analysis.

RESULTS

One hundred eighty-eight unique studies were included (n = 8928 participants). Compliance to HIIT interventions averaged 89.4% (SD:11.8%), while adherence to HIIT averaged 63% (SD: 21.1%). Compliance and adherence to MICT averaged 92.5% (SD:10.6%) and 68.2% (SD:16.2%), respectively. Based on 65 studies included in the meta-analysis, compliance rates were not different between supervised HIIT and MICT interventions [Hedge's g = 0.015 (95%CI: - 0.088-0.118), p = .78]. Results were robust and low risk of publication bias was detected. No differences were detected based on sub-group analyses comparing medical conditions or risk of bias of studies. Quality of the evidence was rated as moderate over concerns in the directness of the evidence. Based on 10 studies, adherence rates were not different between unsupervised HIIT and MICT interventions [Hedge's g = - 0.313 (95%CI: - 0.681-0.056), p = .096]. Sub-group analysis points to differences in adherence rates dependent on the method of outcome measurement. Adherence results should be interpreted with caution due to very low quality of evidence.

CONCLUSIONS

Compliance to HIIT and MICT was high among insufficiently active adults and adults with a medical condition. Adherence to HIIT and MICT was relatively moderate, although there was high heterogeneity and very low quality of evidence. Further research should take into consideration exercise protocols employed, methods of outcome measurement, and measurement timepoints.

REGISTRATION

This review was registered in the PROSPERO database and given the identifier CRD42019103313.

The effects of exercise training on circulating adhesion molecules in adults: A systematic review and meta-analysis

INTRODUCTION

The current meta-analysis investigated the effects of exercise training on circulating adhesion molecules i.e. soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in adults.

METHOD

PubMed, Web of Science, Scopus and Embase were searched to identify original articles, published in English languages journal from inception up to 31 August 2023 that compared the effects of exercise training with non-exercising control on sICAM-1 and sVCAM-1 in adults. Standardized mean differences (SMDs) and 95% CIs were calculated using random-effect models.

RESULTS

Twenty-three studies including 31 intervention arms and involving 1437 subjects were included in the meta-analysis. Exercise training effectively reduced sICAM-1 [SMD: -0.33 (95% CI -0.56 to -0.11), p = 0.004; I2 = 56.38%, p = 0.001; 23 intervention arms]. Subgroup analyses showed that sICAM-1 decreased in adults with age <60 years (p = 0.01) and BMI ≥ 27 kg/m2 (p = 0.002) and those with metabolic disorders (p = 0.004) and cardiovascular diseases (p = 0.005). In addition, aerobic (p = 0.02) and resistance training (p = 0.007) are effective in reducing sICAM-1. However, exercise training did not indicate a superior effect on sVCAM-1 [SMD: -0.12 (95% CI -0.29 to 0.05), p = 0.17; I2 = 36.29%, p = 0.04; 23 intervention arms].

CONCLUSION

Our results show that exercise training reduces sICAM-1, but not for sVCAM-1, where both aerobic and resistance training is effective in reducing sICAM-1 in adults with metabolic disorders and cardiovascular diseases.

TRIAL REGISTRATION

The current meta-analysis was registered at www.crd.york.ac.uk/prospero with ID registration number: CRD42023410474.

Recommending swimming to people with low back pain: A scoping review

BACKGROUND

It is common practice for health professionals to recommend swimming to people with low back pain (LBP) despite limited evidence. The aim of this review was to gain an understanding of the current evidence base supporting the recommendation of swimming to people with LBP.

METHODS

A scoping review was conducted searching five electronic databases, CINAHL, MEDLINE, PEDro, PubMed, and SPORTdiscus using the keywords back pain AND swim*. The studies were grouped by study design and the following uncertainties were considered; the impact of swimming on the spine and LBP, evidence of swimming increasing or reducing the risk of LBP and the use of swimming in LBP rehabilitation programmes.

RESULTS

25 studies met the eligibility criteria; including sixteen observational studies exploring the relationship between swimming and LBP, three biomechanical studies investigating the impact of swimming on the spine, and five interventional studies of which four integrated swimming into a rehabilitation programme and one used swimming to modify lumbar lordosis.

CONCLUSION

The review confirmed there is limited research and only low-level evidence to support the recommendation of swimming to people with LBP. Observational studies make up the greater proportion of research undertaken in the field; the data indicates that swimming is a low-risk form of exercise but not without risk. The findings from biomechanical research suggest that lumbar lordosis does not increase excessively when swimming breaststroke, but certain swimming techniques could negatively impact LBP and interventional trials illustrate that there are various ways to integrate swimming into a rehabilitation programme.

The effects of exercise training on postprandial glycemia and insulinemia in adults with overweight or obesity and with cardiometabolic disorders: a systematic review and meta-analysis

BACKGROUND

We performed a systematic review and meta-analysis to investigate the effects of exercise training on postprandial glycemia (PPG) and insulinemia (PPI) in adults with overweight or obesity and with cardiometabolic disorders.

METHODS

PubMed, Web of Science, and Scopus databases were searched until May 2022 using the key words "exercise," "postprandial," and "randomized control trial" to identify original studies investigating the effects of exercise training on PPG and/or PPI in adults with a body mass indexes (BMI) ≥ 25 kg.m². Standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated using random effects models to calculate effect sizes for outcomes and to generate forest plots. Sub-group analyses and meta-regressions were performed for potential categorical and continuous moderators.

RESULTS

Twenty-nine studies involving 41 intervention arms and 1,401 participants were included in the systematic review and meta-analysis. Overall, exercise training significantly decreased PPG [-0.36 (95% CI -0.50 to -0.22), p=0.001] and PPI [-0.37 (95% CI -0.52 to -0.21), p=0.001]. Subgroup analyses showed that PPG decreased following both aerobic and resistance training; whereas PPI was reduced following aerobic training, independent of age, BMI, and baseline glucose levels. Meta-regression analyses showed that frequency of exercise sessions, intervention durations, and duration of exercise time, did not moderate the effects of exercise training on PPI or PPG (p>0.05).

CONCLUSION

In adults with overweight or obesity and with cardiometabolic disorders, exercise training is effective for reducing PPG and PPI, across ages and BMIs, irrespective of baseline glucose levels and exercise training characteristics.

Effects of aquatic high-intensity interval training and moderate-intensity continuous training on central hemodynamic parameters, endothelial function and aerobic fitness in inactive adults

Objective

The effects of land-based high-intensity interval training (HIIT) on the cardiovascular system have already been demonstrated. However, the water environment is different from that on land. Therefore, we investigated the effects of 6-week aquatic HIIT and moderate-intensity continuous training (MICT) on central hemodynamic parameters, endothelial function, and aerobic fitness in inactive adults.

Methods

Thirty-one inactive adults were randomly assigned to HIIT or MICT group. HIIT group performed twelve 30-s swimming exercise bouts with the intensity of 95% HR_max and 15-18/20 RPE with a 60-s rest period between each bout. MICT group performed a 30-min uninterrupted swimming exercise with the intensity of 70%-75% HR_max and 12-14/20 RPE. Training frequency for both groups was three times a week. The pulse wave analysis and flow-mediated dilation (FMD) were measured by non-invasive equipments.

Results

The aerobic fitness significantly increased after HIIT, but no change was seen after MICT. Augmentation pressure (AP) and augmentation index normalized at 75 bpm (AIx@HR75) significantly decreased after HIIT but not MICT, whereas MICT rather than HIIT improved subendocardial viability ratio (SEVR), central and peripheral blood pressure, and resting HR. Only HIIT significantly increased brachial endothelial function.

Conclusion

A six-week aquatic HIIT and MICT had no differences in hemodynamic parameters, endothelial function, and aerobic fitness, however 6 weeks of aquatic HIIT reduced arterial stiffness, increased endothelial function and aerobic fitness, while 6 weeks of aquatic MICT reduced arterial blood pressure and resting HR and increased the coronary blood flow reserve.

The impact of high-intensity interval training on postprandial glucose and insulin: A systematic review and meta-analysis

AIMS

We performed a systematic review and meta-analysis to investigate the effects of high-intensity interval training (HIIT) on postprandial glucose (PPG) and insulin (PPI) versus non-exercise control and moderate-intensity continuous training (MICT) in participants with both normal and impaired glucose.

METHODS

The PubMed, Scopus, and Web of Science electronic databases were searched up to October 2021 for randomized trials evaluating HIIT versus control and/or versus MICT on glucose and insulin AUC using oral glucose tolerance testing. Subgroup analyses based on intervention duration (short-duration < 8 weeks, moderate-duration ≥ 8 weeks), baseline glucose levels (normal glucose and impaired glucose) and type of HIIT (L-HIIT and SIT) were also conducted across included studies.

RESULTS

A total of 25 studies involving 870 participants were included in the current meta-analysis. HIIT effectively reduced glucose [-0.37 (95% CI -0.60 to -0.13), p = 0.002] and insulin [-0.36 (95% CI -0.68 to -0.04), p = 0.02] AUC when compared with a CON group. Reductions in glucose AUC were significant for those with impaired glucose at baseline (p = 0.03), but not for those with normal glucose levels (p = 0.11) and following moderate-duration (p = 0.01), but not short-duration interventions (p = 0.18). However, there were no differences in glucose (p = 0.76) or insulin (p = 0.43) AUC between HIIT and MICT intervention arms.

CONCLUSIONS

Our results demonstrated that both HIIT and MICT are effective for reducing postprandial glycemia and insulinemia, particularly by moderate-duration interventions, and in those with impaired glucose.

The effect of aquatic High Intensity Interval Training on cardiometabolic and physical health markers in women: A systematic review and meta-analysis

Background

We performed a meta-analysis of randomized controlled trials (RCTs) assessing the effect of Aquatic High Intensity Interval Training (AHIIT) on cardiometabolic and physical health markers in women.

Methods

Systematic search used 7 databases (MEDLINE, PubMed, SPORTDiscus, Cochrane, Embase, CINAL complete, PsycINFO). The Physiotherapy Evidence Database (PEDro) score was used to evaluate the methodological quality of the studies. Clinical trials compared AHIIT with a control group that receive no exercise training. We integrated randomized controlled trials published in English, and participants were women aged ≥18 years. The outcome of interest was the change in cardiometabolic and physical health markers.

Results

Among 242 articles screened, 18 articles (13 trials) were included in this meta-analysis comparing AHIIT (n = 261) with a control group (n = 215). The median PEDro score was 5.5 out of 10 (range, 4–8). AHIIT significantly improved peak oxygen uptake (Hedges' g 0.610; 95% CI 0.277–0.943; P < 0.001), reduced resting heart rate (Hedges' g −0.495; 95% CI -0.866 to −0.124; P < 0.05), as well as chair to stand test. (Hedges’ g 0.548; 95% CI 0.019 to 1.077; P < 0.05).

Conclusion

AHIIT has a moderate effect in improving cardiometabolic and physical health markers in women.

Body mass conversion and improved insulin response in Colombian Paso horses subjected to a swimming training program

Overweight and obesity in horses affect their athletic performance negatively, making it therefore necessary to develop training protocols that reduce their body fat without causing hoof injuries. The objective of the study was to describe the effect of the application of a swimming training program on metabolic and endocrine variables, in addition to evaluating the changes in subcutaneous fat thickness (SFT) in a group of overweight Colombian Paso Horses (CPHs). Six CPHs were subjected to a decreasing intensity swimming program for four months. The effect of this training on metabolic variables (i.e. aspartate aminotransferase, creatine kinase, triglycerides, cholesterol, glucose) and endocrines (cortisol and insulin) was studied every two months. Additionally, changes in the neck, lumbar, and gluteal SFTs were evaluated. The information was analysed using descriptive statistics, in addition to repeated measures analysis of variance for non-parametric data in the three training moments (P<0.1) and correlation analysis between the SFT and the metabolic and endocrine variables of interest. The swimming training program for CPHs tested in this study produced more evident redistribution of adipose tissue in the gluteal region (Initial SFT = 5.2±2.08 mm; Final SFT = 3.45±2.8 mm), conversion of body mass without weight modification, and use of energy sources such as triglycerides and increased sensitivity to insulin. A limitation of the study was that the horses were not selected according to age, nor were control animals used. In addition, the limited number of horses makes extrapolation of the results inappropriate. In conclusion, the swimming training program with decreasing intensity carried out over a four-month period modified body adipose tissue in CPHs, promoting the use of energy sources, such as triglycerides and increased insulin sensitivity.

Slow and Steady, or Hard and Fast? A Systematic Review and Meta-Analysis of Studies Comparing Body Composition Changes between Interval Training and Moderate Intensity Continuous Training

Purpose: To conduct a systematic review and multilevel meta-analysis of the current literature as to the effects of interval training (IT) vs moderate intensity continuous training (MICT) on measures of body composition, both on a whole-body and regional level. Methods: We searched English-language papers on PubMed/MEDLINE, Scopus, CINAHL, and sportrxiv for the following inclusion criteria: (a) randomized controlled trials that directly compared IT vs MICT body composition using a validated measure in healthy children and adults; (b) training was carried out a minimum of once per week for at least four weeks; (c) published in a peer-reviewed English language journal or on a pre-print server. Results: The main model for fat mass effects revealed a trivial standardized point estimate with high precision for the interval estimate, with moderate heterogeneity (−0.016 (95%CI −0.07 to 0.04); I² = 36%). The main model for fat-free mass (FFM) effects revealed a trivial standardized point estimate with high precision for the interval estimate, with negligible heterogeneity (−0.0004 (95%CI −0.05 to 0.05); I² = 16%). The GRADE summary of findings suggested high certainty for both main model effects. Conclusions: Our findings provide compelling evidence that the pattern of intensity of effort and volume during endurance exercise (i.e., IT vs MICT) has minimal influence on longitudinal changes in fat mass and FFM, which are likely to minimal anyway. Trial registration number: This study was preregistered on the Open Science Framework.

Neither autophagy nor exercise training mode affect exercise-induced beneficial adaptations in high fat-fed mice

Purpose

Methods

Results

Conclusions

Gender-dependent evaluation of football as medicine for prediabetes

PURPOSE

Training intensity and health effects of football were investigated gender specifically in individuals with prediabetes.

METHODS

Participants with prediabetes (age 60 ± 6 years) were randomised into a football and dietary advice group (FD-men n = 13 and FD-women n = 14) or a dietary advice only group (D-men n = 12 and D-women n = 11). FD performed football training (twice/week for 16 weeks), while both groups received dietary advice. Body composition, bone variables, blood pressure, blood lipid profile and peak oxygen uptake (VO2peak) were determined pre- and post-intervention.

RESULTS

Mean heart rate during football training was 79 ± 2 and 80 ± 3% HRmax for FD-men and FD-women, respectively, with peak heart rate values of 96 ± 1 and 97 ± 2% HRmax, with no gender differences. VO2peak increased more (P < 0.05) in FD-men and FD-women than in D-men and D-women. However, relative delta change in VO2peak was 21 ± 14% in FD-women, which was greater (P < 0.05) than in FD-men (11 ± 12%). Reduction in SBP and DBP, respectively, was similar in FD-men (- 10.8 ± 13.0 and - 7.3 ± 11.8 mmHg) and FD-women (- 11.3 ± 11.0 and - 7.1 ± 6.2 mmHg), with within-gender differences for men. Total plasma cholesterol and LDL cholesterol decreased (P < 0.05) by - 0.7 ± 1.1 and - 0.5 ± 0.9 mmol L-1, respectively, in FD-women and - 0.2 ± 0.4 and - 0.2 ± 0.3 mmol L-1 in FD-men, with no significant gender differences (P = 0.08). Body fat content was lowered (P < 0.05) by 3 and 4%-points in FD-men and FD-women, respectively.

CONCLUSION

Gender-mixed football training combined with dietary advice causes broad-spectrum health effects for men and women with prediabetes, with minor gender-specific differences. Thus, the intensity and training-induced effects of football training are also high for elderly women with prediabetes.

Prevalence and predictors of dropout from high-intensity interval training in sedentary individuals: A meta-analysis

Recent evidence suggests that high-intensity interval training (HIIT) is an effective method to improve fitness and various health markers. However, the tolerability and acceptability of HIIT among sedentary individuals is currently controversially discussed. Therefore, our objective was to investigate the prevalence and predictors of dropout among sedentary individuals in HIIT-based exercise interventions. MEDLINE/PubMed, SPORTDiscus, and Web of Science were searched systematically for relevant articles until 06/2018. Studies included were required to (a) be written in English, (b) include sedentary healthy adults, (c) use some form of HIIT without any complementary intervention, (d) last ≥4 weeks, (e) report detailed description of the applied HIIT protocol, and (f) report data that allow calculation of a dropout rate. Fifty-five studies reporting results from 67 HIIT interventions with 1318 participants met the eligibility criteria. The trim and fill adjusted pooled dropout rate across all interventions was 17.6% (95% confidence interval 14.2-21.5%). Dropout rates were significantly lower in cycling-based interventions compared with studies using running/walking as exercise modality (P < 0.001). Longer session time (β = 0.02, P < 0.05), higher time effort/week (β = 0.005, P < 0.05), and overall time effort/intervention (β = 0.0003, P < 0.05) predicted greater dropout. Exercise intensity was not related to dropout. Our data suggest that HIIT-based interventions are tolerable and acceptable for previously sedentary individuals, exhibiting generally lower dropout rates than commonly reported for traditional exercise programs. Given the association between HIIT volume and dropouts, future studies should further focus on identifying the minimally effective dose of practical HIIT for improving health status. Such efforts would be important to increase implementation and public health impact of HIIT.

Acute Effects of Exercise Intensity on Insulin Sensitivity under Energy Balance

Exercise is known to improve insulin sensitivity (SI); however, studies to date have been confounded by negative energy deficits after exercise.

PURPOSE

The primary objective of this study was to assess the effect of 8 to 16 wk of aerobic exercise training on the SI of untrained women under rigorously controlled energy-balanced conditions. The secondary objective was to determine if one acute bout of moderate-intensity continuous (MIC) or high-intensity interval (HII) exercise further affected SI.

METHODS

Insulin sensitivity was assessed in 28 untrained women at baseline, after 8 to 16 wk of training with no-exercise (NE) before assessment, 22 h after MIC (50% V˙O2peak), and 22 h after HII (84% V˙O2peak) using a hyperinsulinemic-euglycemic clamp. Participants were in a whole-room indirect calorimeter during each condition, and food intake was adjusted to ensure energy balance across 23 h before each clamp.

RESULTS

There were no significant differences in acute energy balance between each condition. Results indicated a significant main effect of time, such that SI was higher during the HII condition compared with both baseline and NE (P < 0.05). No significant differences in SI were observed after NE or MIC.

CONCLUSIONS

Widely reported improvements in SI in response to chronic exercise training may be mediated in part by shifts in energy balance. However, an acute bout of HII exercise may increase SI even in the context of energy balance.

Is interval training the magic bullet for fat loss? A systematic review and meta-analysis comparing moderate-intensity continuous training with high-intensity interval training (HIIT)

OBJECTIVES

To compare the effects of interval training and moderate-intensity continuous training (MOD) on body adiposity in humans, and to perform subgroup analyses that consider the type and duration of interval training in different groups.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

English-language, Spanish-language and Portuguese-language searches of the electronic databases PubMed and Scopus were conducted from inception to 11 December 2017.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies that met the following criteria were included: (1) original articles, (2) human trials, (3) minimum exercise training duration of 4 weeks, and (4) directly or indirectly compared interval training with MOD as the primary or secondary aim.

RESULTS

Of the 786 studies found, 41 and 36 were included in the qualitative analysis and meta-analysis, respectively. Within-group analyses showed significant reductions in total body fat percentage (%) (interval training: -1.50 [95% CI -2.14 to -0.86, p<0.00001] and MOD: -1.44 [95% CI -2.00 to -0.89, p<0.00001]) and in total absolute fat mass (kg) (interval training: -1.58 [95% CI -2.74 to -0.43, p=0.007] and MOD: -1.13 [95% CI -2.18 to -0.08, p=0.04]), with no significant differences between interval training and MOD for total body fat percentage reduction (-0.23 [95% CI -1.43 to 0.97], p=0.705). However, there was a significant difference between the groups in total absolute fat mass (kg) reduction (-2.28 [95% CI -4.00 to -0.56], p=0.0094). Subgroup analyses comparing sprint interval training (SIT) with MOD protocols favour SIT for loss of total absolute fat mass (kg) (-3.22 [95% CI -5.71 to -0.73], p=0.01). Supervised training, walking/running/jogging, age (<30 years), study quality and intervention duration (<12 weeks) favourably influence the decreases in total absolute fat mass (kg) observed from interval training programmes; however, no significant effect was found on total body fat percentage (%). No effect of sex or body mass index was observed on total absolute fat mass (kg) or total body fat percentage (%).

CONCLUSION

Interval training and MOD both reduce body fat percentage (%). Interval training provided 28.5% greater reductions in total absolute fat mass (kg) than MOD.

TRIAL REGISTRATION NUMBER

CRD42018089427.

The Impact of High-Intensity Interval Training on Brain Derived Neurotrophic Factor in Brain: A Mini-Review

The brain-derived neurotrophic factor (BDNF) is a protein mainly synthetized in the neurons. Early evidence showed that BDNF participates in cognitive processes as measured at the hippocampus. This neurotrophin is as a reliable marker of brain function; moreover, recent studies have demonstrated that BDNF participates in physiological processes such as glucose homeostasis and lipid metabolism. The BDNF has been also studied using the exercise paradigm to determine its response to different exercise modalities; therefore, BDNF is considered a new member of the exercise-related molecules. The high-intensity interval training (HIIT) is an exercise protocol characterized by low work volume performed at a high intensity [i.e., ≥80% of maximal heart rate (HRmax)]. Recent evidence supports the contention that HIIT elicits higher fat oxidation in skeletal muscle than other forms of exercise. Similarly, HIIT is a good stimulus to increase maximal oxygen uptake (VO₂max). Few studies have investigated the impact of HIIT on the BDNF response. The present work summarizes the effects of acute and long-term HIIT on BDNF.

Chronic Physiological Effects of Swim Training Interventions in Non-Elite Swimmers: A Systematic Review and Meta-Analysis

BACKGROUND

Swimming is a popular and potentially health-enhancing exercise, but has received less scientific attention compared with other exercise modes.

OBJECTIVE

The objective of the study was to determine the chronic (long-term) effect of pool swim training on physiological outcomes in non-elite or non-competitive swimming participants.

DESIGN

This study was a systematic review with a meta-analysis.

DATA SOURCES

We searched the electronic databases PubMed, EMBASE and CENTRAL from inception to March 2017.

ELIGIBILITY CRITERIA

The eligibility criteria included randomised controlled trials, quasi-randomised controlled trials and controlled trials of chronic (long-term) swimming interventions in non-elite or non-competitive swimming participants, with a physiological outcome measure.

RESULTS

Our search of 6712 records revealed 29 eligible studies. Swimming had a significant and clinically meaningful effect on maximal oxygen uptake compared with the control in an analysis including multiple populations (mean difference 6.32 mL/kg/min; 95% confidence interval 4.33-8.31), and subgroup analyses of healthy children/adolescents (mean difference 7.93 mL/kg/min; 95% confidence interval 3.31-12.55) and those with asthma (mean difference 9.67 mL/kg/min; 95% confidence interval 5.84-13.51) and healthy adults (mean difference 5.87 mL/kg/min; 95% confidence interval 2.93-8.81). Swimming also resulted in significant improvements in other cardiorespiratory fitness-related outcomes such as maximal minute ventilation (mean difference 0.61 L/min; 95% confidence interval 0.17-1.05), submaximal exercise performance (standardised mean difference 0.64; 95% confidence interval 0.14-1.13) and total exercise test time (mean difference 4.27 min; 95% confidence interval 2.11-6.42). Compared with the control, swimming had significant favourable effects on body mass (mean difference - 2.90 kg, 95% confidence interval - 5.02 to - 0.78), body fat percentage in multiple populations (mean difference - 1.92%; 95% confidence interval - 3.25 to - 0.60) and healthy children/adolescents (mean difference - 1.92%; 95% confidence interval - 4.64 to - 0.80) and lean mass (mean difference 1.96 kg; 95% confidence interval 0.21-3.71), but negative effects on waist circumference in a pooled analysis of two studies involving adults with hypertension (mean difference 4.03 cm; 95% confidence interval 2.58-5.49). Regarding lung function, significant effects of swimming vs. the control were found only for peak expiratory volume in analyses including children/adolescents combined with healthy adults (mean difference 58.74 L/min; 95% confidence interval 29.70-87.78) and children/adolescents with asthma alone (mean difference 63.49 L/min; 95% confidence interval 25.01-101.97). Based on limited data, swimming had similar effects to other exercise modes, except for higher post-intervention body mass index values with swimming vs. running in healthy adults (mean difference 1.18 kg/m²; 95% confidence interval 0.54-1.81).

CONCLUSIONS

Swimming may offer robust beneficial effects on cardiorespiratory fitness and body composition across multiple populations and effects may be comparable to other exercise modes. Future randomised controlled trials are required to establish the effectiveness of swimming on physiological outcomes in healthy populations and those with non-communicable disease.

The effect of aquatic high-intensity interval training on aerobic performance, strength and body composition in a non-athletic population: systematic review and meta-analysis

Objective:

In a non-athletic population, to (1) investigate the effectiveness of high-intensity interval training in an aquatic environment (A-HIIT) on aerobic performance, strength, and body composition and (2) report on safety of this approach.

Method:

A systematic search was undertaken of six databases until May 2018. Trials were eligible for inclusion if they compared the effect of A-HIIT in a non-athletic population with a control group that received no exercise training. Data were extracted independently by two reviewers and meta-analyses were undertaken using a random effects model to produce standardized mean difference (SMD) and 95% confidence intervals (CIs). Risk of bias was assessed using Cochrane’s risk of bias tool. All studies were graded using Physiotherapy Evidence Database (PEDro) and Consensus for Exercise Reporting Template (CERT) scales to determine quality of reporting.

Results:

Eight studies reported over 13 papers met study criteria ( n = 377). Compared with a control group, those who completed a program of A-HIIT demonstrated greater aerobic performance (SMD 0.69 (95% CI 0.39–0.98); I2 = 0%; n = 191) and lower limb muscle strength (SMD 0.30 (95% CI 0.04–0.56); I2 = 0%; n = 237). No differences were seen in measures of body composition or the number of adverse events. All studies were at risk of performance bias. The (mean ± SD) PEDro and CERT scores were 4.9 ± 1.5 and 15.1 ± 2.1, respectively.

Conclusion:

In a non-athletic population, A-HIIT was safe and may have improved aerobic performance and lower limb strength. The exercise interventions were well described and monitoring and reporting of exercise intensity in water was feasible.

Reducing sitting time versus adding exercise: differential effects on biomarkers of endothelial dysfunction and metabolic risk

Recent studies suggest that substituting sitting with light physical activity has beneficial metabolic effects, but it is unclear if this is associated with parallel changes in endothelial function. Data from three randomized cross-over studies were analyzed, in which 61 subjects (with normal weight, overweight and type 2 diabetes) followed different activity regimens (Sit, SitLess and/or Exercise) of four days each. Subjects were instructed to sit 14 h/day (‘Sit’), to substitute 1 h/day of sitting with moderate-to-vigorous cycling (‘Exercise’) or to substitute 5–6 h/day sitting with light-intensity walking and standing (‘SitLess’). Physical activity was assessed 24 h/day by accelerometry (ActivPAL) and diet was standardized. Fasted circulating biomarkers of endothelial dysfunction, lipids and insulin sensitivity were assessed the morning after each activity regimen. The endothelial dysfunction score (ED-score) was computed by averaging the Z-scores of the circulating biomarkers of endothelial dysfunction. Compared to Sit, Exercise resulted in lower ED-score, sICAM1 and sE-selectin (p < 0.05), while no significant changes were observed after SitLess. The ED-score, sVCAM1 and sE-selectin were lower after Exercise compared to SitLess (p < 0.05). In contrast, compared to Sit, insulin sensitivity (HOMA2-IR) and plasma lipids (HDL-cholesterol, non-HDL-cholesterol, total cholesterol and Apo B) did not change significantly after Exercise but were improved after SitLess (p < 0.05). In conclusion, light physical activity and moderate-to-vigorous physical activity had a differential effect on risk markers of cardio-metabolic health and suggest the need of both performing structured exercise as well as reducing sitting time on a daily basis.

Physical Activity Recommendations for Health and Beyond in Currently Inactive Populations

Widespread persistent inactivity makes continued efforts in physical activity promotion a persistent challenge. The precise content of physical activity recommendations is not broadly known, and there are concerns that the general messaging of the guidelines, including the recommendations to perform at least 150 min of at least moderate intensity physical activity per week might seem unattainable for and even actually discourage currently inactive people. Here we show that there are a myriad of ways of being physically active, and provide (in part) out-of-the-box examples of evidence based, pragmatic, easily accessible physical activity regimes below 150 min and/or with lower than moderate intensity that yield meaningful health benefits for currently inactive people.

Plasma pentraxin 3 and glucose kinetics following acute high-intensity interval exercise versus continuous moderate-intensity exercise in healthy men

Pentraxin 3 (PTX3) is mainly synthesized and released by neutrophils to help regulate innate immunity. While plasma PTX3 concentrations are associated with improved glucose metabolism and overall metabolic health, there is evidence that significant elevations in plasma glucose downregulate circulating levels of PTX3. To examine whether this relationship would be altered in response to exercise, this study investigated the kinetics of the plasma glucose and PTX3 responses following high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CMIE). It was hypothesized that the increased concentrations of plasma glucose following HIIE compared with CMIE would be associated with an attenuated plasma PTX3 response. Eight healthy male subjects participated in both HIIE and CMIE protocols administered as a randomized, counterbalanced design. Linear mixed models for repeated measures revealed that the overall plasma glucose response was greater following HIIE compared with CMIE (protocol × time effect: p = 0.037). Although the plasma PTX3 response was higher only at 19 min into HIIE compared with CMIE (protocol × time effect: p = 0.013), no relationships were observed between plasma glucose and PTX3 either at baseline or in response to both exercise protocols, as indicated by the area under the curve "with respect to increase" analysis. Our results indicate that exercise-mediated plasma PTX3 concentrations are independent of the plasma glucose response. In addition, the present study suggests that the neutrophil-mediated innate immune response, as indicated by plasma PTX3 response, may be activated earlier during HIIE compared with CMIE.

Football training improves metabolic and cardiovascular health status in 55- to 70-year-old women and men with prediabetes

We examined the effects of 16 weeks of football training and dietary advice on blood glucose control and health status in 55- to 70-year-old women and men with prediabetes. Fifty participants with prediabetes (age; 61 ± 6 years, BMI; 29.6 ± 4.7; VO_2max 22.3 ± 5.7 mL·min^-1 ·kg^-1 ) were randomized into a football and dietary advice group (F+D; n = 27) and a dietary advice group (D; n = 23). F+D performed football training (twice weekly 30- to 60-minutes sessions) and received dietary advice, while D only received dietary advice. An oral glucose tolerance test (OGTT) was completed pre and post the 16-week period. Body composition, blood pressure, and maximal oxygen uptake (VO_2max ) were additionally measured. Both groups demonstrated a decrement (P < .05) in fasting blood glucose (-0.4 ± 0.5 mmol·L^-1 ) and lowered blood glucose throughout OGTT. F+D displayed lower values than D (P < .05) after 60 minutes (9.0 ± 2.7 vs 10.6 ± 2.9 mmol·L^-1 ) and 120 minutes (5.7 ± 1.6 vs 7.5 ± 2.4 mmol·L^-1 ). VO_2max increased by 14% in F+D, with a higher (P < .05) change score than in D (2%). Mean arterial pressure declined more (P < .05) in F+D than in D (-8 ± 9 vs -4 ± 11 mm Hg). Fat loss was greater (P < .05) in F+D than in D (-3.4 ± 2.8 vs -1.2 ± 2.0 kg), and the increase in lean body mass was also greater (P < .05) in F+D than in D (0.7 ± 1.5 vs -0.3 ± 1.6 kg). In conclusion, football training combined with dietary advice has broad-spectrum effects on metabolic and cardiovascular health profile with greater overall effects than professional dietary advice per se for 55- to 70-year-old women and men with prediabetes.

Effects of combined high-intensity aerobic interval training program and Mediterranean diet recommendations after myocardial infarction (INTERFARCT Project): study protocol for a randomized controlled trial

BACKGROUND

Exercise therapy has long been used for rehabilitation purposes after myocardial infarction (MI) and the benefit of regular physical exercise is also well-established. High-intensity interval training (HIIT) has been proposed to be more effective than continuous exercise for improving exercise capacity and health-related adaptations to low-volume (LV) and HIIT are also known. Furthermore, the Mediterranean diet (Mediet) has been widely reported to be a model of healthy eating for its contribution to a favorable health status and a better quality of life, reducing overall mortality. This study will investigate the effects of different HIIT programs (high-volume [HV] vs LV) and Mediet recommendations in clinical condition, cardiorespiratory fitness, biomarkers, ventricular function, and perception of quality of life after MI, and compared to an attention control group that is recommended to Mediet and physical activity without supervision sessions.

METHODS/DESIGN

In this randomized controlled trial, cardiorespiratory fitness, anthropometry, central and peripheral cardiovascular variables, biochemical and nutritional condition, and quality of life will be assessed before and after 16 weeks of intervention in 177 participants diagnosed with MI type 1. All participants will be randomly (1:1:1) assigned to the attention control group or two exercise groups (Mediet recommendations plus supervised aerobic exercise two days/week: (1) HV (40 min) HIIT group and (2) LV (20 min) HIIT group.

DISCUSSION

This study will be the first clinical trial comparing the effects of two different volumes of HIIT programs with Mediet recommendations for people after MI. The results of this study will provide good evidence for physical rehabilitation in this population.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02876952 . Registered on 24 August 2016.

Effects of self-paced interval and continuous training on health markers in women

PURPOSE

To compare the effects of self-paced high-intensity interval and continuous cycle training on health markers in premenopausal women.

METHODS

Forty-five inactive females were randomised to a high-intensity interval training (HIIT; n = 15), continuous training (CT; n = 15) or an inactive control (CON; n = 15) group. HIIT performed 5 × 5 min sets comprising repetitions of 30-s low-, 20-s moderate- and 10-s high-intensity cycling with 2 min rest between sets. CT completed 50 min of continuous cycling. Training was completed self-paced, 3 times weekly for 12 weeks.

RESULTS

Peak oxygen uptake (16 ± 8 and 21 ± 12%), resting heart rate (HR) (-5 ± 9 and -4 ± 7 bpm) and visual and verbal learning improved following HIIT and CT compared to CON (P < 0.05). Total body mass (-0.7 ± 1.4 kg), submaximal walking HR (-3 ± 4 bpm) and verbal memory were enhanced following HIIT (P < 0.05), whereas mental well-being, systolic (-5 ± 6 mmHg) and mean arterial (-3 ± 5 mmHg) blood pressures were improved following CT (P < 0.05). Participants reported similar levels of enjoyment following HIIT and CT, and there were no changes in fasting serum lipids, fasting blood [glucose] or [glucose] during an oral glucose tolerance test following either HIIT or CT (P > 0.05). No outcome variable changed in the CON group (P > 0.05).

CONCLUSIONS

Twelve weeks of self-paced HIIT and CT were similarly effective at improving cardiorespiratory fitness, resting HR and cognitive function in inactive premenopausal women, whereas blood pressure, submaximal HR, well-being and body mass adaptations were training-type-specific. Both training methods improved established health markers, but the adaptations to HIIT were evoked for a lower time commitment.

Physiological adaptations induced by swimming in mice fed a high fat diet

This study examined physiological variables of animals fed with a high-fat diet (HFD) or with a normal diet (ND) subjected to swimming at low and moderate level. Over 16 weeks, a group of animals was fed with HFD or ND, and at the 8 weeks, they started swimming with 50% or 80% of the maximum load achieved in the progressive work test. Weekly, body weight and the amount of ingested food were registered. The glycemic level was measured at the beginning, middle and at the end of the experiment. Adipose tissue, gastrocnemius muscles and hearts were collected for morphometry. The results showed that the animals fed an HFD had a minor caloric intake; however, the HFD increased body weight and adiposity, likely causing cardiac hypertrophy and an increase in the glycemic level. In this context, swimming with an 80% load contributed positively to weight control, adiposity, glycemic level, to control cardiac hypertrophy and induce hypertrophy in the gastrocnemius muscle. All parameters assessed showed better results for the ND animals. Therefore, the importance of fat consumption was emphasized in relation to obesity onset. The practice of swimming with an 80% load produced greater benefits than swimming with a 50% load for overweight treatment.