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

Guideline Approaches for Cardioendocrine Disease Surveillance and Treatment Following Spinal Cord Injury

PURPOSE OF REVIEW

Persons with spinal cord injuries (SCI) commonly experience individual risks and coalesced health hazards of the cardiometabolic syndrome (CMS). This review will examinethe role of exercise and nutritional intervention as countermeasures to these disease risks.

RECENT FINDINGS

The CMS hazards of overweight/obesity, insulin resistance, hypertension, and dyslipidemia are strongly associated with physical deconditioning and are common after SCI. Both the CMS diagnosis and physical deconditioning worsen the prognosis for all-cause cardiovascular disease occurring early after SCI. Evidence supports a therapeutic role for physical activity after SCI as an effective countermeasure to these risks and often represents the first-line approach to CMS abatement. This evidence is supported by authoritative systematic reviews and associated guidelines that recommend specific activities, frequencies, and activities of work. In many cases, the most effective exercise programming uses more intense periods of work with limited rest. As SCI is also associated with poor dietary habits, including excessive energy intake and saturated fat consumption, more comprehensive lifestyle management incorporating both exercise and nutrition represents a preferred approach for overall health management.

SUMMARY

Irrespective of the interventional strategy, improved surveillance of the population for CMS risks and encouraged incorporation of exercise and nutritional management according to recent population-specific guidelines will most likely play an important role in the preservation of activity, optimal health, and independence throughout the lifespan.

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.

Effect of High-Intensity Interval Training on Total, Abdominal and Visceral Fat Mass: A Meta-Analysis

BACKGROUND

High-intensity interval training (HIIT) is promoted as a time-efficient strategy to improve body composition.

OBJECTIVE

The aim of this meta-analysis was to assess the efficacy of HIIT in reducing total, abdominal, and visceral fat mass in normal-weight and overweight/obese adults.

METHODS

Electronic databases were searched to identify all related articles on HIIT and fat mass. Stratified analysis was performed using the nature of HIIT (cycling versus running, target intensity), sex and/or body weight, and the methods of measuring body composition. Heterogeneity was also determined RESULTS: A total of 39 studies involving 617 subjects were included (mean age 38.8 years ± 14.4, 52% females). HIIT significantly reduced total (p = 0.003), abdominal (p = 0.007), and visceral (p = 0.018) fat mass, with no differences between the sexes. A comparison showed that running was more effective than cycling in reducing total and visceral fat mass. High-intensity (above 90% peak heart rate) training was more successful in reducing whole body adiposity, while lower intensities had a greater effect on changes in abdominal and visceral fat mass. Our analysis also indicated that only computed tomography scan or magnetic resonance imaging showed significant abdominal and/or visceral fat-mass loss after HIIT interventions.

CONCLUSION

HIIT is a time-efficient strategy to decrease fat-mass deposits, including those of abdominal and visceral fat mass. There was some evidence of the greater effectiveness of HIIT running versus cycling, but owing to the wide variety of protocols used and the lack of full details about cycling training, further comparisons need to be made. Large, multicenter, prospective studies are required to establish the best HIIT protocols for reducing fat mass according to subject characteristics.

Objectively measured absolute and relative physical activity intensity levels in postmenopausal women

OBJECTIVES

To investigate how objectively measured physical activity (PA) levels differ according to absolute moderate intensity recommendation (3-6 METs) and relative to individual lactate thresholds (LT1 and LT2), and to verify if high-fit women record higher PA levels compared to women with lower aerobic fitness.

METHODS

Seventy-five postmenopausal women performed an incremental exercise test and several constant-velocity tests wearing an accelerometer to identify the activity counts (ct min^-1) corresponding to LT1 and LT2. Individual linear regression determined activity counts cut-points for each intensity: (1) sedentary (<200 ct min^-1), (2) light (from 200 ct min^-1 to ct min^-1 at LT1), (3) moderate (ct min^-1 between LT1 and LT2) and (4) vigorous (ct min^-1> LT2). Participants then wore an accelerometer during a week to measure the time spent at each PA intensity level.

RESULTS

According to absolute intensity categorisation, high-fit postmenopausal women recorded twice as much time at moderate-to-vigorous PA (MVPA) (P < 0.01) than low-fit women. However, when PA intensity was calculated relative to individual lactate thresholds, MVPA was significantly reduced by half (P < 0.01) and the data revealed no differences (P = 0.62) between groups (∼20 min day^-1 at MVPA).

CONCLUSIONS

Accelerometer cut-points derived from absolute moderate-intensity recommendations overestimated MVPA. Similar time at MVPA was recorded by high- and low-fit postmenopausal women when the cut-points were tailored to individual lactate thresholds. A more accurate estimation of PA behaviour could be provided with the use of individually tailored accelerometer cut-points.

Effectiveness of exercise training after bariatric surgery-a systematic literature review and meta-analysis

We aimed to conduct a systematic review and meta-analysis of controlled trials assessing exercise training programs in patients with obesity undergoing bariatric surgery. We systematically searched exercise training studies performed after bariatric surgery published up to June 2017. Studies reporting changes in body composition, physical fitness, functional capacity, objectively measured physical activity, quality of life or relevant health outcomes were included. The review protocol is available from PROSPERO (CRD42017069380). Meta-analyses were conducted using random-effects models when data were available from at least five articles. Twenty articles were included, describing 16 exercise training programs, of which 15 were included in the meta-analysis. Overall, exercise training was associated with higher weight loss (mean difference: -2.4 kg, 95% CI: -4.2; -0.6, I²  = 49%, n = 12), higher fat mass loss (-2.7 kg, 95% CI: -4.5; -1.0, I²  = 50%, n = 8) and improved VO₂ max and functional walking (standardized mean difference: 0.86, 95% CI: 0.29; 1.44, I²  = 57%, n = 6; 1.45, 95% CI: 0.32; 2.58, I²  = 89%, n = 6, respectively). Exercise training was not associated with lean body mass changes. In conclusion, exercise training programs performed after bariatric surgery were found effective to optimize weight loss and fat mass loss and to improve physical fitness, although no additional effect on lean body mass loss was found.

Deciphering V̇ O2,max: limits of the genetic approach

Maximal oxygen consumption (V̇ _O2,max) denotes the upper limit of aerobic energy flux through the cascade of oxygen transfer from the environment to tissue mitochondria, essentially to skeletal muscle mitochondria during intense exercise. A high V̇ _O2,max is a key component for athletic success in human and animal endurance sports. From a public health perspective, a high V̇ _O2,max is a validated negative predictor for cardiovascular disease and all-cause mortality. V̇ _O2,max varies by more than twofold between sedentary subjects and shows a heritability value greater than 50%. Likewise, the capacity for an individual's V̇ _O2,max to be increased with exercise training (i.e. its trainability) varies massively between subjects, independent of each subject's V̇ _O2,max in the absence of training (i.e. their sedentary V̇ _O2,max), and with a similarly high heritability. Athletic as well as public health interests have prompted a search for the genetic profile of sedentary V̇ _O2,max and of trainability. Candidate-gene studies, gene-expression studies and genome-wide-association studies (GWAS) have not been able to identify a genetic signature that distinguishes subjects or athletes with a favorable V̇ _O2,max phenotype or a high trainability from controls. Here, I propose that multigenetic phenotypes such as V̇ _O2,max are emergent properties of multiple underlying transcriptomic networks modified by epistasis, the epigenome and the epitranscriptome. The genetic approach is thus considered to be necessary but insufficient for furthering our understanding of multigenetic higher-level functions.

Comparison of Acute Physiological and Psychological Responses Between Moderate-Intensity Continuous Exercise and Three Regimes of High-Intensity Interval Training

Olney, N, Wertz, T, LaPorta, Z, Mora, A, Serbas, J, and Astorino, TA. Comparison of acute physiological and psychological responses between moderate-intensity continuous exercise and three regimes of high intensity interval training. J Strength Cond Res 32(8): 2130-2138, 2018-High-intensity interval training (HIIT) elicits similar physiological adaptations as moderate-intensity continuous training (MICT) despite less time commitment. However, there is debate whether HIIT is more aversive than MICT. This study compared physiological and perceptual responses between MICT and 3 regimes of HIIT. Nineteen active adults (age = 24.0 ± 3.3 years) unfamiliar with HIIT initially performed ramp exercise to exhaustion to measure maximal oxygen uptake (V[Combining Dot Above]O2max) and determine workload for subsequent sessions, whose order was randomized. Sprint interval training (SIT) consisted of six 20-second bouts of "all-out" cycling at 140% of maximum watts (Wmax). Low-volume HIIT (HIITLV) and high-volume HIIT (HIITHV) consisted of eight 60-second bouts at 85% Wmax and six 2-minute bouts at 70% Wmax, respectively. Moderate-intensity continuous training consisted of 25 minutes at 40% Wmax. Across regimes, work was not matched. Heart rate (HR), V[Combining Dot Above]O2, blood lactate concentration (BLa), affect, and rating of perceived exertion (RPE) were assessed during exercise. Ten minutes postexercise, Physical Activity Enjoyment (PACES) was measured via a survey. Results revealed significantly higher (p ≤ 0.05) V[Combining Dot Above]O2, HR, BLa, and RPE in SIT, HIITLV, and HIITHV vs. MICT. Despite a decline in affect during exercise (p < 0.01) and significantly lower affect (p ≤ 0.05) during all HIIT regimes vs. MICT at 50, 75, and 100% of session duration, PACES was similar across regimes (p = 0.65), although it was higher in women (p = 0.03). Findings from healthy adults unaccustomed to interval training demonstrate that HIIT and SIT are perceived as enjoyable as MICT despite being more aversive.

Effect of high-intensity interval training on cardiovascular disease risk factors and body composition in psoriatic arthritis: a randomised controlled trial

Background

Psoriatic arthritis (PsA) is associated with an accumulation of cardiovascular disease (CVD) risk factors. The aim of this study was to evaluate the effect of high-intensity interval training (HIIT) on CVD risk factors in patients with PsA.

Methods

We randomly assigned 61 patients with PsA (41 women and 20 men) to an intervention group performing HIIT for 11 weeks or a control group who were instructed to not change their physical exercise habits. Outcomes were assessed at 3 and 9  months with measures on maximal oxygen uptake (VO_2max), fat percentage and Body Mass Index (BMI). We used linear mixed models to calculate mean difference with 95% CI between the groups according to the intention-to-treat principle.

Results

At 3  months, the HIIT group had a 3.72  mL/kg/min (95%  CI 2.38 to 5.06) higher VO_2max and a 1.28 (95% CI −2.51 to −0.05) lower truncal fat percentage than controls. There was also some evidence that the HIIT group had lower total fat percentage (−0.80; 95%  CI −1.71 to 0.10) and slightly lower BMI (−0.31; 95%  CI −0.78 to 0.17) than the control group. At 9  months, the HIIT group had still a higher VO_2max (3.08; 95%  CI 1.63 to 4.53) than the control group, whereas the difference in other factors were small.

Conclusion

In patients with PsA, 3  months with HIIT was associated with a substantial increase in VO_2max and a reduction in truncal fat percentage compared with controls. The beneficial effect on VO_2max was also sustained through 9  months.

Trial registration number

NCT02995460.

Meta-analysis of Exercise Training on Left Ventricular Ejection Fraction in Heart Failure with Reduced Ejection Fraction: A 10-year Update

BACKGROUND

The role of exercise training modality to attenuate left ventricular (LV) remodeling in heart failure patients with reduced ejection fraction (HFrEF) remains uncertain. The authors performed a systematic review and meta-analysis of published reports on exercise training (moderate-intensity continuous aerobic, high-intensity interval aerobic, and resistance exercise) and LV remodeling in clinically stable HFrEF patients.

METHODS

We searched MEDLINE, Cochrane Central Registry of Controlled Trials, CINAHL, and PubMed (2007 to 2017) for randomized controlled trials of exercise training on resting LV ejection fraction (EF) and end-diastolic and end-systolic volumes in HFrEF patients.

RESULTS

18 trials reported LV ejection fraction (LVEF) data, while 8 and 7 trials reported LV end-diastolic and LV end-systolic volumes, respectively. Overall, moderate-intensity continuous training (MICT) significantly increased LVEF (weighted mean difference, WMD = 3.79%; 95% confidence interval, CI, 2.08 to 5.50%) with no change in LV volumes versus control. In trials ≥6 months duration, MICT significantly improved LVEF (WMD = 6.26%; 95% CI 4.39 to 8.13%) while shorter duration (<6 months) trials modestly increased LVEF (WMD = 2.33%; 95% CI 0.84 to 3.82%). High-intensity interval training (HIIT) significantly increased LVEF compared to control (WMD = 3.70%; 95% CI 1.63 to 5.77%) but was not different than MICT (WMD = 3.17%; 95% CI -0.87 to 7.22%). Resistance training performed alone or combined with aerobic training (MICT or HIIT) did not significantly change LVEF.

CONCLUSIONS

In clinically stable HFrEF patients, MICT is an effective therapy to attenuate LV remodeling with the greatest benefits occurring with long-term (≥6 months) training. HIIT performed for 2 to 3 months is superior to control, but not MICT, for improvement of LVEF.

Short-Term (<8 wk) High-Intensity Interval Training in Diseased Cohorts

BACKGROUND AND AIM

Exercise training regimes can lead to improvements in measures of cardiorespiratory fitness (CRF), improved general health, and reduced morbidity and overall mortality risk. High-intensity interval training (HIIT) offers a time-efficient approach to improve CRF in healthy individuals, but the relative benefits of HIIT compared with traditional training methods are unknown in across different disease cohorts.

METHODS

This systematic review and meta-analysis compares CRF gains in randomized controlled trials of short-term (<8 wk) HIIT versus either no exercise control (CON) or moderate continuous training (MCT) within diseased cohorts. Literature searches of the following databases were performed: MEDLINE, EMBASE, CINAHL, AMED, and PubMed (all from inception to December 1, 2017), with further searches of Clinicaltrials.gov and citations via Google Scholar. Primary outcomes were effect on CRF variables: V˙O2peak and anaerobic threshold.

RESULTS

Thirty-nine studies met the inclusion criteria. HIIT resulted in a clinically significant increase in V˙O2peak compared with CON (mean difference [MD] = 3.32 mL·kg·min, 95% confidence interval [CI] = 2.56-2.08). Overall HIIT provided added benefit to V˙O2peak over MCT (MD = 0.79 mL·kg·min, 95% CI = 0.20-1.39). The benefit of HIIT was most marked in patients with cardiovascular disease when compared with MCT (V˙O2peak: MD = 1.66 mL·kg·min, 95% CI = 0.60-2.73; anaerobic threshold: MD = 1.61 mL·kg·min, 95% CI = 0.33-2.90).

CONCLUSIONS

HIIT elicits improvements in objective measures of CRF within 8 wk in diseased cohorts compared with no intervention. When compared with MCT, HIIT imparts statistically significant additional improvements in measures of CRF, with clinically important additional improvements in V˙O2peak in cardiovascular patients. Comparative efficacy of HIIT versus MCT combined with an often reduced time commitment may warrant HIIT's promotion as a viable clinical exercise intervention.

Personal Activity Intelligence and Mortality in Patients with Cardiovascular Disease: The HUNT Study

OBJECTIVE

To test whether Personal Activity Intelligence (PAI), a personalized metric of physical activity (PA) tracking, is associated with all-cause and cardiovascular disease (CVD) mortality in patients with self-reported CVD and to determine whether these associations change depending on whether contemporary PA recommendations are met.

PATIENTS AND METHODS

A total of 3133 patients with CVD (mean [SD] age, 67.6 [10.3] years; 64% men) were followed from the date of participation in the Nord-Trøndelag Health Study (between January 1, 1984, and February 28, 1986) until the date of death or the end of follow-up (December 31, 2015). The participants' weekly PAI score was calculated and divided into 4 groups (PAI scores of 0, ≤50, 51-99, and ≥100). We used Cox proportional hazards regression models to estimate hazard ratios for CVD and all-cause mortality rates.

RESULTS

After mean follow-up of 12.5 years (39,157 person-years), there were 2936 deaths (94%), including 1936 CVD deaths. Participants with weekly PAI scores of 100 or greater had 36% (95% CI, 21%-48%) and 24% (95% CI, 10%-35%) lower risk of mortality from CVD and all causes, respectively, compared with the inactive group. Participants had similar risk reductions associated with their weekly PAI scores regardless of following contemporary PA recommendations or not.

CONCLUSION

Obtaining a weekly PAI score of at least 100 was associated with lower mortality risk from CVD and all causes in individuals with CVD regardless of whether the current PA recommendations were met.

Predictors of change in affect in response to high intensity interval exercise (HIIE) and sprint interval exercise (SIE)

Affect is typically positive at intensities below the lactate or ventilatory threshold, yet more aversive responses occur at supra-threshold intensities which may reduce positive perceptions of exercise. Completion of high intensity interval exercise (HIIE) typically elicits a reduction in affect, yet greater post-exercise enjoyment has been reported in response to HIIE versus moderate intensity continuous exercise (MICE). This study examined affectual responses to HIIE and sprint interval exercise (SIE) in 71 active men and women (age = 24.0 ± 4.8 year). Participants performed various HIIE and SIE regimes on the cycle ergometer during which affect (+5 - -5 scale), rating of perceived exertion (RPE, Borg 1-10 scale), and blood lactate concentration (BLa) were determined. Enjoyment was measured post-exercise using the PACES scale. Predictors of change in these variables in response to exercise were identified using multiple regression. Results showed a significant reduction in affect (p = .001) which was greater (p = .03) with SIE (-5.7 ± 2.7) compared to HIIE (-4.3 ± 2.4). Nevertheless, there was marked variability in the affect response across participants, as its change ranged from -1 to -7 units from pre- to post-exercise in 85% of all sessions. Sixty two percent of the change in affect seen across regimes was explained by baseline affect, BLa, and enjoyment. Significant associations were shown between the change in affect and baseline affect (r = -0.46, p < .001) and change in RPE (r = -0.59, p < .001). In addition, RPE significantly increased in response to HIIE (6.1 ± 1.7) and SIE (6.9 ± 2.0) but was not different (p = .050) between regimes. Our findings document an intensity-dependent relationship between affect and intensity during interval training, as supramaximal intensities elicit a larger decline in affect compared to submaximal intensities. In addition, pre-exercise affect is associated with the magnitude of change in affect reported in response to interval exercise.

Evaluating the progressive cardiovascular health benefits of short-term high-intensity interval training

PURPOSE

High-intensity training is recognised as a time-efficient way of improving aerobic fitness. However, there is a lack of consensus regarding the temporal nature of adaptation response and which peripheral and cardiac changes occur using the same exercise stimulus and protocol. Therefore, this study aimed to evaluate the progression of vascular and cardiac changes over a 6-week training period.

METHODS

Twelve healthy males (age 21 ± 2 years; 42.5 ± 8.3 ml min^-1 kg^-1) participated in a high-intensity training programme consisting of 1-min sprints, interspersed with 2 min active recovery, 3 days/week for 6 weeks on a cycle ergometer. Cardiac, vascular, blood lipids and VO_2max measurements were taken at 0, 3 and 6 weeks and compared against a participant-matched control group (age 21 ± 2 years; 37.7 ± 8.3 ml min^-1 kg^-1).

RESULTS

There was a significant improvement in VO_2max (42.5 ± 8.3-47.4 ± 8.5 ml min^-1 kg^-1; p = 0.009) in the training group and a significant decrease in systolic blood pressure (8%) from 0 to 6 weeks (p = 0.025). There was a small yet significant decrease in ejection fraction and increased end-systolic volume in both groups over time (p = 0.01) with no significant interaction effect (p > 0.05). A between-group difference in peak velocity of early diastolic mitral annular motion was also observed (p = 0.01). No improvements were seen in blood lipid profiles, central arterial stiffness and cardiometabolic risk score.

CONCLUSIONS

Six weeks of high-intensity training increases aerobic fitness and is enough to stimulate initial reductions in peripheral pressure, but not sufficient to elicit structural and functional cardiac changes, reduce arterial stiffness or lower CV risk.

Comparing Time Efficiency of Sprint vs. High-Intensity Interval Training in Reducing Abdominal Visceral Fat in Obese Young Women: A Randomized, Controlled Trial

Introduction: High-intensity interval training (HIIT) is an emerging lifestyle intervention strategy for controlling obesity. HIIT consisted of brief all-out supramaximal sprint intervals was termed as sprint interval training (SIT). This study was designed to examine the time-efficient characteristics of SIT in reducing abdominal visceral fat. Methods: A randomized controlled trial was conducted to compare the specific adaptations of SIT (80 × 6 s all-out cycle sprints interspersed with 9 s passive recovery) with those resulting from a HIIT regimen with training volume relatively higher (repeated 4 min bouts of cycling at 90% V˙ O_2max alternated with 3 min rest, until the work of 400KJ was achieved), and with those of nonexercising control counterparts (CON). Forty-six obese young women (body fat percentage ≥30) received either SIT (n = 16), HIIT (n = 16), or no training (n = 14), 3-4 sessions per week, for 12 weeks. The abdominal visceral fat area (AVFA) and abdominal subcutaneous fat area (ASFA) of the participants were measured through computed tomography scans pre-intervention and post-intervention. Total fat mass and the fat mass of the android, gynoid, and trunk regions were assessed through dual-energy X-ray absorptiometry. Results: Following the intervention, abdominal visceral and subcutaneous fat were reduced markedly (p < 0.05). The reduction in AVFA (-6.31, -9.7 cm²) was not different between SIT and HIIT (p > 0.05), while the reduction in ASFA (-17.4, -40.7 cm²) in SIT was less than that in HIIT (p < 0.05). Less reduction in the fat mass of the trunk (-1.2, -2.0 kg) region was also found in SIT, while the reductions in fat percentage (-1.9%, -2.0%), total fat mass (-2.0, -2.8 kg), and fat mass of the android (-0.2, -0.2 kg), and gynoid (-0.4, -0.3 kg) regions did not differ between the two regimes (p > 0.05). In contrast, the increase in V˙ O_2max was significant greater following the SIT than HIIT (p < 0.01). No variable changed in CON. Conclusion: Such findings suggest that the lower training load and exercise time commitments of the SIT regime could optimize the time-efficiency advantage of the traditional HIIT, facilitating the abdominal visceral fat reduction in obese young women.

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.

Effects of high-velocity circuit resistance and treadmill training on cardiometabolic risk, blood markers, and quality of life in older adults

The presence of cardiometabolic syndrome (CMS) confers an increased risk for cardiovascular disease (CVD) and mortality and is associated with reduced health-related quality of life (HRQoL). Although the effects of exercise on biomarkers, HRQoL, and future risk have been studied, no study has measured the effects on all three components. The present study compared the effects of steady-state, moderate-intensity treadmill training (TM) and high-velocity circuit resistance training (HVCRT) on biological markers, HRQoL, and overall CVD risk in adults with CMS and CVD risk factors. Thirty participants (22 females, 8 males) were randomly assigned to 1 of 3 groups: HVCRT, TM, or control. Participants in the exercise groups attended training 3 days/week for a total of 12 weeks. Of the 30 participants who began the study, 24 (19 females, 5 males) were included in the final analysis. Primary outcome measures included CMS criteria, hemodynamic measures, Framingham Risk Score (FRS), and HRQoL. All variables were measured pre- and post-intervention. CMS z score significantly decreased for HVCRT (p = 0.03), while there were no significant changes for TM or control. FRS significantly decreased for HVCRT compared with TM (p = 0.03) and control (p = 0.03). Significant decreases in systolic (p < 0.01) and diastolic blood pressures (p < 0.01) for HVCRT accompanied significant increases from baseline in stroke volume (p = 0.03) and end-diastolic volume (p < 0.01). Systemic vascular resistance significantly decreased (p = 0.05) for HVCRT compared with control. Emotional well-being significantly improved following HVCRT and TM compared with control (p = 0.04; p = 0.03). HVCRT represents a novel training modality that improved factors in each of the 3 components assessed.

Tailored exercise interventions to reduce fatigue in cancer survivors: study protocol of a randomized controlled trial

Background

Cancer-related fatigue (CRF) is a common and distressing symptom of cancer and/or cancer treatment that persists for years after treatment completion in approximately one third of cancer survivors. Exercise is beneficial for the management of CRF, and general exercise guidelines for cancer survivors are available. There are multiple potential pathways by which exercise improves CRF, and cancer survivors with CRF are diverse with respect to cancer type, treatments and experienced side effects. While the general exercise guidelines are likely sufficient for most cancer survivors, tailoring of exercise interventions may be more effective in those with persistent fatigue. The primary aim of this research is to investigate the effect of a traditional vs. tailored exercise intervention on CRF severity in cancer survivors with persistent CRF.

Methods/design

Cancer survivors (≥ 3 months and ≤ 5 years since primary treatment) who score ≤ 34 on the Functional Assessment of Chronic Illness Therapy Fatigue Scale (FACIT-F) will be randomly allocated to one of two parallel treatment arms: traditional (active control) and tailored exercise. Participants in the traditional exercise group will engage in aerobic and resistance exercise that is consistent with exercise guidelines for cancer survivors. The tailored exercise group will be prescribed an intervention designed to address individual deficits identified at baseline, such as loss of muscular strength, cardiorespiratory deconditioning or sleep disturbance. Participants will be assessed before and after the intervention for CRF severity and other patient-reported outcomes, neuromuscular function and fatigue in response to whole-body exercise, sleep quantity and quality, physical activity levels, cardiorespiratory fitness and blood biomarkers.

Discussion

To our knowledge, this will be the first study to compare the effects of a traditional vs. tailored exercise intervention on CRF severity in cancer survivors with persistent CRF. Using physiological, behavioural and patient-reported outcomes, this study will add to the current knowledge about both the factors contributing to CRF, and the potential reduction in CRF severity with an exercise intervention.

Trial registration

The study is registered at ClinicalTrials.gov (NCT03049384), February, 2017.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4668-z) contains supplementary material, which is available to authorized users.

Acute responses of hemodynamic and oxidative stress parameters to aerobic exercise with blood flow restriction in hypertensive elderly women

Systemic arterial hypertension has been associated with the majority deaths from cardiovascular disease, especially among the elderly population, and the imbalance between antioxidant and pro-oxidants has been associated with hypertension. This study analyzed the acute responses of cardiorespiratory and oxidative stress parameters to low intensity aerobic exercise (LIAE) with blood flow restriction (BFR) in hypertensive elderly women. The experimental group consisted of 16 hypertensive women (67.2 ± 3.7 years) who underwent a progressive treadmill test and performed three exercise protocols in random order: high intensity (HIAE), low intensity aerobic exercise (LIAE) and low intensity aerobic exercise with blood flow restriction (LIAE + BFR). Data analysis showed that blood pressure and heart rate augmented from rest to post effort (p < 0.05) and reduced from post effort to recovery (p < 0.05) in all protocols. The values of lipid peroxidation were higher after 30 min of recovery when compared to the moment at rest in the LILIAE + BFR (p < 0.05). The same occurred with glutathione-S-transferase and superoxide dismutase activity. However, non-protein thiols levels (NPSH) reduced after 30 min of recovery when compared to the moment at rest in the LILIAE + BFR protocol (p < 0.05). In the HIAE and LIAE + BFR protocols, the levels of NPSH were lower at 30 min of recovery when compared to the same moment in the LIAE protocol (p < 0.05). LIAE + RBF produces an oxidative status and hemodynamic stimulus similar to HIAE. Taken together, these results support the indication of LIAE with BFR in chronic intervention protocols, with potential benefits for the hypertensive elderly population.

Acute Effects of High-Intensity Interval and Moderate-Intensity Continuous Exercise on GLP-1, Appetite and Energy Intake in Obese Men: A Crossover Trial

This study investigated the effect of high-intensity interval (HIIE) and moderate-intensity continuous exercise (MICE) on glucagon-like peptide 1 (GLP-1), appetite and energy intake (EI) in obese men. In a randomized crossover trial, 12 participants (28.4 ± 2.6 years, 35.5 ± 4.5 kg/m², 39.8 ± 2.2% body fat) performed: (I) Control (CON, no exercise); (II) MICE (20 min, 70% of maximal heart rate) and (III) HIIE (10 × 1 min at 90% of maximal heart rate with 1 min recovery). GLP-1 and appetite were assessed at: (I) PRE: pre-exercise; (II) POST: immediately post-exercise; (III) POST-1 h: 1 h post-exercise. EI was assessed after an ad libitum meal offered 1 h post-exercise and over 24 h. There was a significant time × condition interaction for GLP-1 (p = 0.035). Higher GLP-1 levels in MICE vs. CON (p = 0.024) and a trend for HIIE vs. CON (p = 0.069) POST-1h was found. Hunger was reduced immediately post-HIIE compared to CON (p < 0.01), but was not sustained POST-1 h (p > 0.05). EI did not differ between the sessions 1 h post-exercise or over 24H (p > 0.05). In summary, although MICE increased GLP-1 levels POST-1h and HIIE induced a transient reduction in hunger, both exercise protocols did not impact EI in obese men.

Enhancing and Extending Biological Performance and Resilience

Human performance, endurance, and resilience have biological limits that are genetically and epigenetically predetermined but perhaps not yet optimized. There are few systematic, rigorous studies on how to raise these limits and reach the true maxima. Achieving this goal might accelerate translation of the theoretical concepts of conditioning, hormesis, and stress adaptation into technological advancements. In 2017, an Air Force-sponsored conference was held at the University of Massachusetts for discipline experts to display data showing that the amplitude and duration of biological performance might be magnified and to discuss whether there might be harmful consequences of exceeding typical maxima. The charge of the workshop was "to examine and discuss and, if possible, recommend approaches to control and exploit endogenous defense mechanisms to enhance the structure and function of biological tissues." The goal of this white paper is to fulfill and extend this workshop charge. First, a few of the established methods to exploit endogenous defense mechanisms are described, based on workshop presentations. Next, the white paper accomplishes the following goals to provide: (1) synthesis and critical analysis of concepts across some of the published work on endogenous defenses, (2) generation of new ideas on augmenting biological performance and resilience, and (3) specific recommendations for researchers to not only examine a wider range of stimulus doses but to also systematically modify the temporal dimension in stimulus inputs (timing, number, frequency, and duration of exposures) and in measurement outputs (interval until assay end point, and lifespan). Thus, a path forward is proposed for researchers hoping to optimize protocols that support human health and longevity, whether in civilians, soldiers, athletes, or the elderly patients. The long-term goal of these specific recommendations is to accelerate the discovery of practical methods to conquer what were once considered intractable constraints on performance maxima.

The effect of running versus cycling high-intensity intermittent exercise on local tissue oxygenation and perceived enjoyment in 18-30-year-old sedentary men

BACKGROUND

High-intensity interval training (HIIT) has been proposed as a time-efficient exercise format to improve exercise adherence, thereby targeting the chronic disease burden associated with sedentary behaviour. Exercise mode (cycling, running), if self-selected, will likely affect the physiological and enjoyment responses to HIIT in sedentary individuals. Differences in physiological and enjoyment responses, associated with the mode of exercise, could potentially influence the uptake and continued adherence to HIIT. It was hypothesised that in young sedentary men, local and systemic oxygen utilisation and enjoyment would be higher during a session of running HIIT, compared to a session of cycling HIIT.

METHODS

A total of 12 sedentary men (mean ± SD; age 24 ± 3 years) completed three exercise sessions: a maximal incremental exercise test on a treadmill (MAX) followed by two experiment conditions, (1) free-paced cycling HIIT on a bicycle ergometer (HIITCYC) and (2) constant-paced running HIIT on a treadmill ergometer (HIITRUN). Deoxygenated haemoglobin (HHb) in the gastrocnemius (GN), the left vastus lateralis (LVL) and the right vastus lateralis (RVL) muscles, oxygen consumption (VO2), heart rate (HR), ratings of perceived exertion (RPE) and physical activity enjoyment (PACES) were measured during HIITCYC and HIITRUN.

RESULTS

There was a higher HHb in the LVL (p = 0.001) and RVL (p = 0.002) sites and a higher VO2 (p = 0.017) and HR (p < 0.001) during HIITCYC, compared to HIITRUN. RPE was higher (p < 0.001) and PACES lower (p = 0.032) during HIITCYC compared to HIITRUN.

DISCUSSION

In sedentary individuals, free-paced cycling HIIT produces higher levels of physiological stress when compared to constant-paced running HIIT. Participants perceived running HIIT to be more enjoyable than cycling HIIT. These findings have implications for selection of mode of HIIT for physical stress, exercise enjoyment and compliance.

Change in VO2max and time trial performance in response to high-intensity interval training prescribed using ventilatory threshold

Completion of high-intensity interval training (HIIT) leads to significant increases in maximal oxygen uptake (VO_2max) and oxidative capacity. However, individual responses to HIIT have been identified as approximately 20-40% of individuals show no change in VO_2max, which may be due to the relatively homogeneous approach to implementing HIIT.

PURPOSE

This study tested the effects of HIIT prescribed using ventilatory threshold (VT) on changes in VO_2max and cycling performance.

METHODS

Fourteen active men and women (age and VO_2max = 27 ± 8 year and 38 ± 4 mL/kg/min) underwent nine sessions of HIIT, and 14 additional men and women (age and VO_2max = 22 ± 3 year and 40 ± 5 mL/kg/min) served as controls. Training was performed on a cycle ergometer at a work rate equal to 130%VT and consisted of eight to ten 1 min bouts interspersed with 75 s of recovery. At baseline and post-testing, they completed progressive cycling to exhaustion to determine VO_2max, and on a separate day, a 5 mile cycling time trial.

RESULTS

Compared to the control group, HIIT led to significant increases in VO_2max (6%, p = 0.007), cycling performance (2.5%, p = 0.003), and absolute VT (9 W, p = 0.005). However, only 57% of participants revealed meaningful increases in VO_2max and cycling performance in response to training, and two showed no change in either outcome.

CONCLUSIONS

A greater volume of HIIT may be needed to maximize the training response for all individuals.

Cardiorespiratory Fitness in Severe Mental Illness: A Systematic Review and Meta-analysis

BACKGROUND

Cardiorespiratory fitness (CRF) among people with severe mental illness (SMI) (i.e., schizophrenia, bipolar disorder, and major depressive disorder) is a critical clinical risk factor given its relationship to cardiovascular disease and premature mortality.

OBJECTIVES

This study aimed to: (1) investigate the mean CRF in people with SMI versus healthy controls; (2) explore moderators of CRF; and (3) investigate whether CRF improved with exercise interventions and establish if fitness improves more than body mass index following exercise interventions.

METHODS

Major electronic databases were searched systematically. A meta-analysis calculating Hedges' g statistic was undertaken.

RESULTS

Across 23 eligible studies, pooled mean CRF was 28.7 mL/kg/min [95 % confidence interval (CI) 27.3 to 30.0 mL/kg/min, p < 0.001, n = 980]. People with SMI had significantly lower CRF compared with controls (n = 310) (Hedges' g = -1.01, 95 % CI -1.18 to -0.85, p < 0.001). There were no differences between diagnostic subgroups. In a multivariate regression, first-episode (β = 6.6, 95 % CI 0.6-12.6) and inpatient (β = 5.3, 95 % CI 1.6-9.0) status were significant predictors of higher CRF. Exercise improved CRF (Hedges' g = 0.33, 95 % CI = 0.21-0.45, p = 0.001), but did not reduce body mass index. Higher CRF improvements were observed following interventions at high intensity, with higher frequency (at least three times per week) and supervised by qualified personnel (i.e., physiotherapists and exercise physiologists).

CONCLUSION

The multidisciplinary treatment of people with SMI should include a focus on improving fitness to reduce all-cause mortality. Qualified healthcare professionals supporting people with SMI in maintaining an active lifestyle should be included as part of multidisciplinary teams in mental health treatment.

Size Exponents for Scaling Maximal Oxygen Uptake in Over 6500 Humans: A Systematic Review and Meta-Analysis

BACKGROUND

Maximal oxygen uptake ([Formula: see text] _2max) is conventionally normalized to body size as a simple ratio or using an allometric exponent < 1. Nevertheless, the most appropriate body size variable to use for scaling and the value of the exponent are still enigmatic. Studies tend to be based on small samples and can, therefore, lack precision.

OBJECTIVE

The objective of this systematic review was to provide a quantitative synthesis of reported static allometric exponents used for scaling [Formula: see text] _2max to whole body mass and fat-free mass.

METHODS

Eight electronic databases (CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, PubMed, Scopus, SPORTDiscus and Web of Science) were searched for relevant studies published up to January 2016. Search terms included 'oxygen uptake', 'cardiorespiratory fitness', '[Formula: see text] _2max', '[Formula: see text] _2peak', 'scaling' and all interchangeable terms. Inclusion criteria included human cardiorespiratory fitness data; cross-sectional study designs; an empirical derivation of the exponent; reported precision statistics; and reported information regarding participant sex, age and sports background, [Formula: see text] _2max protocol, whole body composition protocol and line-fitting methods. A random-effects model was used to quantify weighted pooled exponents and 95% confidence limits (Cls). Heterogeneity was quantified with the tau-statistic (τ). Meta-regression was used to quantify the impact of selected moderator variables on the exponent effect size. A 95% prediction interval was calculated to quantify the likely range of true fat-free mass exponents in similar future studies, with this distribution used to estimate the probability that an exponent would be above theorised universal values of [Formula: see text].

RESULTS

Thirty-six studies, involving 6514 participants, met the eligibility criteria. Whole body mass and fat-free mass were used as the scaling denominator in 27 and 15 studies, respectively. The pooled allometric exponent (95% Cls) was found to be 0.70 (0.64 to 0.76) for whole body mass and 0.90 (0.83 to 0.96) for fat-free mass. The between-study heterogeneity was greater for whole body mass (τ = ±0.15) than for fat-free mass (τ = ±0.11). Participant sex explained 30% of the between-study variability in the whole body mass exponent, but the influence on the fat-free mass exponent was trivial. The whole body mass exponent of 0.52 (0.40 to 0.64) for females was substantially lower than the 0.76 (0.70 to 0.83) for males, whereas the fat-free mass exponent was similar for both sexes. The effects of all other moderators were trivial. The 95% PI for fat-free mass ranged from 0.68 to 1.12. The estimated probability of a true fat-free mass exponent in a future study being greater than [Formula: see text] power scaling is 0.98 (very likely) and 0.92 (likely), respectively.

CONCLUSIONS

In this quantitative synthesis of published studies involving over 6500 humans, the whole body mass exponent was found to be spuriously low and prone to substantial heterogeneity. We conclude that the scaling of [Formula: see text] _2max in humans is consistent with the allometric cascade model with an estimated prediction interval for the fat-free mass exponent not likely to be consistent with the [Formula: see text] power laws.

High intensity interval training for people with multiple sclerosis: A systematic review

BACKGROUND

Aerobic high intensity interval training (HIIT) is safe in the general population and more efficient in improving fitness than continuous moderate intensity training. The body of literature examining HIIT in multiple sclerosis (MS) is expanding but to date a systematic review has not been conducted. The aim of this review was to investigate the efficacy and safety of HIIT in people with MS.

METHODS

A systematic search was carried out in September 2017 in EMBASE, MEDline, PEDro, CENTRAL and Web of Science Core collections using appropriate keywords and MeSH descriptors. Reference lists of relevant articles were also searched. Articles were eligible for inclusion if they were published in English, used HIIT, and included participants with MS. Quality was assessed using the PEDro scale. The following data were extracted using a standardised form: study design and characteristics, outcome measures, significant results, drop-outs, and adverse events.

RESULTS

Seven studies (described by 11 articles) were identified: four randomised controlled trials, one randomised cross-over trial and two cohort studies. PEDro scores ranged from 3 to 8. Included participants (n = 249) were predominantly mildly disabled; one study included only people with progressive MS. Six studies used cycle ergometry and one used arm ergometry to deliver HIIT. One study reported six adverse events, four which could be attributed to the intervention. The other six reported that there were no adverse events. Six studies reported improvements in at least one outcome measure, however there were 60 different outcome measures in the seven studies. The most commonly measured domain was fitness, which improved in five of the six studies measuring aspects of fitness. The only trial not to report positive results included people with progressive and a more severe level of disability (Extended Disability Status Scale 6.0-8.0).

CONCLUSION

HIIT appears to be safe and effective in increasing fitness in people with MS and low levels of disability. Further research is required to explore the effectiveness of HIIT in people with progressive MS and in those with higher levels of disability.

Exercise fidelity and progression in a supervised exercise programme for adults with venous leg ulcers

Despite exercise being included in the recommended advice for patients with venous leg ulcers, there is a fear shared by clinicians and patients that exercise may be either inappropriate or harmful and actually delay rather than promote healing. Therefore, before implementing a larger-scale study exploring the effects of a supervised exercise programme in patients with venous ulcers being treated with compression therapy, it is important to assess exercise safety as well as fidelity and progression in a feasibility study. Eighteen participants randomised in the exercise group were asked to undertake 36 (3 times/week for 12 weeks) 60-min exercise sessions, each comprising moderate-intensity aerobic, resistance, and flexibility exercise components. For the purposes of this paper, we analysed the data collected during the exercise sessions. The overall session attendance rate was 79%, with 13 of 18 participants completing all sessions. No in-session adverse events were reported; 100% aerobic components and 91% of resistance components were completed within the desired moderate-intensity target. Similarly, 81% of aerobic components and 93% of flexibility components were completed within the prescribed duration targets. Our data showed that patients with venous ulcers could safely follow a supervised exercise programme incorporating moderate-intensity aerobic, resistance, and flexibility components.

Combining Short-Term Interval Training with Caloric Restriction Improves ß-Cell Function in Obese Adults

Although low-calorie diets (LCD) improve glucose regulation, it is unclear if interval exercise (INT) is additive. We examined the impact of an LCD versus LCD + INT training on ß-cell function in relation to glucose tolerance in obese adults. Twenty-six adults (Age: 46 ± 12 year; BMI 38 ± 6 kg/m²) were randomized to 2-week of LCD (~1200 kcal/day) or energy-matched LCD + INT (60 min/day alternating 3 min at 90 and 50% HRpeak). A 2 h 75 g oral glucose tolerance test (OGTT) was performed. Insulin secretion rates (ISR) were determined by deconvolution modeling to assess glucose-stimulated insulin secretion ([GSIS: ISR/glucose total area under the curve (tAUC)]) and ß-cell function (Disposition Index [DI: GSIS/IR]) relative to skeletal muscle (Matsuda Index), hepatic (HOMA-IR) and adipose (Adipose-IR_fasting) insulin resistance (IR). LCD + INT, but not LCD alone, reduced glucose and total-phase ISR tAUC (Interactions: p = 0.04 and p = 0.05, respectively). Both interventions improved skeletal muscle IR by 16% (p = 0.04) and skeletal muscle and hepatic DI (Time: p < 0.05). Improved skeletal muscle DI was associated with lower glucose tAUC (r = -0.57, p < 0.01). Thus, LCD + INT improved glucose tolerance more than LCD in obese adults, and these findings relate to ß-cell function. These data support LCD + INT for preserving pancreatic function for type 2 diabetes prevention.

CC002/Unc females are mouse models of exercise-induced paradoxical fat response

Exercise results in beneficial health outcomes and protects against a variety of chronic diseases. However, U.S. exercise guidelines recommend identical exercise programs for everyone, despite individual variation in responses to these programs, including paradoxical fat gain. Experimental models of exercise-induced paradoxical outcomes may enable the dissection of underlying physiological mechanisms as well as the evaluation of potential interventions. Whereas several studies have identified individual mice exhibiting paradoxical fat gain following exercise, no systematic effort has been conducted to identify and characterize models of paradoxical response. Strains from the Collaborative Cross (CC) genetic reference population were used due to its high levels of genetic variation, its reproducible nature, and the observation that the CC is a rich source of novel disease models, to assess the impact genetic background has on exercise responses. We identified the strain CC002/Unc as an exercise-induced paradoxical fat response model in a controlled voluntary exercise study across multiple ages in female mice. We also found sex and genetic differences were consistent with this pattern in a study of forced exercise programs. These results provide a novel model for studies to determine the mechanisms behind paradoxical metabolic responses to exercise, and enable development of more rational personalized exercise recommendations based on factors such as age, sex, and genetic background.

Brachial artery endothelial function is unchanged after acute sprint interval exercise in sedentary men and women

NEW FINDINGS

What is the central question of this study? What is the acute brachial artery endothelial function response to sprint interval exercise and are there sex-based differences? What is the main finding and its importance? Brachial artery endothelial function did not change in either men or women following an acute session of SIT consisting of 3 × 20 s 'all-out' cycling sprints. Our findings suggest this low-volume protocol may not be sufficient to induce functional changes in the brachial artery of sedentary, but otherwise healthy adults.

ABSTRACT

Sprint interval training (SIT) is a potent metabolic stimulus, but studies examining its acute effects on brachial artery endothelial function are limited. The influence of oestradiol on the acute arterial response to this type of exercise is also unknown. We investigated the brachial artery endothelial function response to a single session of SIT in sedentary healthy men (n = 8; 22 ± 4 years) and premenopausal women tested in the mid-follicular phase of the menstrual cycle (n = 8; 21 ± 3 years). Participants performed 3 × 20 s 'all-out' cycling sprints interspersed with 2 min of active recovery. Brachial artery flow-mediated dilatation (FMD) and haemodynamic parameters were measured before and 1 and 24 h post-exercise. Despite attenuations in some haemodynamic parameters at 1 h post-exercise, there were no changes in absolute (P = 0.23), relative (P = 0.23) or allometrically scaled FMD (P = 0.38) following a single session of SIT. Resting and peak dilatory diameters did not change in men or women (P > 0.05 for all) and there were no interactions between time and sex for any measure (P > 0.05). Oestradiol was not correlated with relative FMD at baseline (r = -0.22, P = 0.42) or with the change in relative FMD from baseline to 1 h post-exercise (r = 0.24, P = 0.40). Overall, brachial artery FMD appears to be unchanged in men and women following an acute session of SIT, and the higher oestradiol concentrations in women do not augment the baseline or post-exercise FMD response. The 3 × 20 s model of low-volume sprint interval exercise may not be sufficient to alter brachial artery endothelial function in healthy men and women.

Feasibility, Safety, and Preliminary Effectiveness of a Home-Based Self-Managed High-Intensity Interval Training Program Offered to Long-Term Manual Wheelchair Users

Objectives

To investigate and compare the feasibility, safety, and preliminary effectiveness of home-based self-managed manual wheelchair high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) programs.

Methods

Eleven manual wheelchair users were randomly assigned to the HIIT (n = 6) or the MICT group (n = 5). Both six-week programs consisted of three 40-minute propulsion training sessions per week. The HIIT group alternated between 30 s high-intensity intervals and 60 s low-intensity intervals, whereas the MICT group maintained a constant moderate intensity. Cardiorespiratory fitness, upper limb strength, and shoulder pain were measured before and after the programs. Participants completed a questionnaire on the programs that explored general areas of feasibility.

Results

The answers to the questionnaire demonstrated that both training programs were feasible in the community. No severe adverse events occurred, although some participants experienced increased shoulder pain during HIIT. Neither program yielded a significant change in cardiorespiratory fitness or upper limb strength. However, both groups reported moderate to significant subjective improvement.

Conclusion

Home-based wheelchair HIIT appears feasible and safe although potential development of shoulder pain remains a concern and should be addressed with a future preventive shoulder exercise program. Some recommendations have been proposed for a larger study aiming to strengthen evidence regarding the feasibility, safety, and effectiveness of HIIT.

Feasibility of high-intensity training in asthma

Background: High-intensity interval training is an effective and popular training regime but its feasibility in untrained adults with asthma is insufficiently described.

Objective: The randomized controlled trial ‘EFFORT Asthma’ explored the effects of behavioural interventions including high-intensity interval training on clinical outcomes in nonobese sedentary adults with asthma. In this article we present a sub analysis of data aiming to evaluate if patients’ pre-intervention levels of asthma control, FEV1, airway inflammation and airway hyperresponsiveness (AHR) predicted their training response to the high-intensity interval training program, measured as increase in maximal oxygen consumption (VO₂max).

Design: We used data from the EFFORT Asthma Study. Of the 36 patients randomized to the 8-week exercise intervention consisting of high-intensity training three times per week, 29 patients (45% females) completed the study and were included in this data analysis. Pre-intervention assessment included the asthma control questionnaire (ACQ), spirometry, fractional exhaled nitric oxide (FeNO) and AHR to mannitol. VO₂ max was measured during an incremental cycle test.

Results: The majority of included patients had partly or uncontrolled asthma reflected by a mean (SD) ACQ at 1.7 (0.6). Median (IQR) FeNO was 28.5 (23.8) ppb and 75% had a positive mannitol test indicating AHR.

The association between patients’ training response measured as increase in VO₂max and pre-intervention ACQ scores was not statistically significant (p = 0.49). Likewise, the association between patients’ increase in VO₂max and FeNO as well as AHR was not statistically significant (p = 0.80 and p = 0.58).

Conclusions: Included asthma patients could adhere to the high-intensity interval protocol and improve their VO₂max regardless of pre-intervention levels of asthma control, airway inflammation and AHR.

Physiological Redundancy and the Integrative Responses to Exercise

The biological responses to acute and chronic exercise are marked by a high level of physiological redundancy that operates at various levels of integration, including the molecular, cellular, organ-system, and whole-body scale. During acute exercise, this redundancy protects whole-body homeostasis in the face of 10-fold or more increases in whole-body metabolic rate. In some cases, there are "trade-offs" between optimizing the performance of a given organ or system versus whole-body performance. Physiological redundancy also plays a key role in the adaptive responses to exercise training and high levels of habitual physical activity, including the positive effects of regular exercise on health. Appreciation of the general principles of physiological redundancy is critical to (1) gain an overall understanding of short- and long-term responses to exercise, and (2) place physiological responses occurring at various levels of integration in perspective.

Australian cardiac rehabilitation exercise parameter characteristics and perceptions of high-intensity interval training: a cross-sectional survey

Purpose

This study explored current demographics, characteristics, costs, evaluation methods, and outcome measures used in Australian cardiac rehabilitation (CR) programs. It also determined the actual usage and perceptions of high-intensity interval training (HIIT).

Methods

A cross-sectional observational web-based survey was distributed to 328 Australian CR programs nationally.

Results

A total of 261 programs completed the survey (79.6% response rate). Most Australian CR programs were located in a hospital setting (76%), offered exercise sessions once a week (52%) for 6-8 weeks (49%) at moderate intensity (54%) for 46-60 min (62%), and serviced 101-500 clients per annum (38%). HIIT was reported in only 1% of programs, and 27% of respondents believed that it was safe while 42% of respondents were unsure. Lack of staff (25%), monitoring resources (20%), and staff knowledge (18%) were the most commonly reported barriers to the implementation of HIIT. Overall, Australian CR coordinators are unsure of the cost of exercise sessions.

Conclusion

There is variability in CR delivery across Australia. Only half of programs reassess outcome measures postintervention, and cost of exercise sessions is unknown. Although HIIT is recommended in international CR guidelines, it is essentially not being used in Australia and clinicians are unsure as to the safety of HIIT. Lack of resources and staff knowledge were perceived as the biggest barriers to HIIT implementation, and there are inconsistent perceptions of prescreening and monitoring requirements. This study highlights the need to educate health professionals about the benefits and safety of HIIT to improve its usage and patient outcomes.

High-intensity interval training or continuous training, combined or not with fasting, in obese or overweight women with cardiometabolic risk factors: study protocol for a randomised clinical trial

INTRODUCTION

Physical inactivity and increased caloric intake play important roles in the pathophysiology of obesity. Increasing physical activity and modifying eating behaviours are first-line interventions, frequently hampered by lack of time to exercise and difficulties in coping with different diets. High-intensity interval training (HIIT) may be a time-efficient method compared with moderate-intensity continuous training (CT). Conversely, diets with a fasting component may be more effective than other complex and restrictive diets, as it essentially limits caloric intake to a specified period without major diet composition changes. Therefore, the combination of HIIT and fasting may provide incremental benefits in terms of effectiveness and time efficiency in obese and sedentary populations. The aim of this study is to determine the effect of HIIT versus CT, combined or not with fasting, on microcirculatory function, cardiometabolic parameters, anthropometric indices, cardiorespiratory fitness and quality of life in a population of sedentary overweight or obese women with cardiometabolic risk factors.

METHODS AND ANALYSIS

Sedentary women aged 30-50 years, with a body mass index ≥25 kg/m2 and cardiometabolic risk factors, will be randomised to HIIT performed in the fasting state, HIIT performed in the fed state, CT in the fasting state or CT in the fed state. Cardiometabolic parameters, anthropometric indices, cardiorespiratory fitness, quality of life and microvascular function (cutaneous capillary density and microvascular reactivity evaluated by laser speckle contrast imaging) will be evaluated before initiation of the interventions and 16 weeks thereafter.

ETHICS AND DISSEMINATION

The trial complies with the Declaration of Helsinki and has been approved by the local ethics committee (Instituto Nacional de Cardiologia, Rio de Janeiro, Brazil). All patients provide written informed consent before enrolment and randomisation. The study's results will be disseminated to the healthcare community by publications and presentations at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03236285.

High-Intensity Interval Training After Stroke: An Opportunity to Promote Functional Recovery, Cardiovascular Health, and Neuroplasticity

INTRODUCTION

Stroke is the leading cause of adult disability. Individuals poststroke possess less than half of the cardiorespiratory fitness (CRF) as their nonstroke counterparts, leading to inactivity, deconditioning, and an increased risk of cardiovascular events. Preserving cardiovascular health is critical to lower stroke risk; however, stroke rehabilitation typically provides limited opportunity for cardiovascular exercise. Optimal cardiovascular training parameters to maximize recovery in stroke survivors also remains unknown. While stroke rehabilitation recommendations suggest the use of moderate-intensity continuous exercise (MICE) to improve CRF, neither is it routinely implemented in clinical practice, nor is the intensity always sufficient to elicit a training effect. High-intensity interval training (HIIT) has emerged as a potentially effective alternative that encompasses brief high-intensity bursts of exercise interspersed with bouts of recovery, aiming to maximize cardiovascular exercise intensity in a time-efficient manner. HIIT may provide an alternative exercise intervention and invoke more pronounced benefits poststroke.

OBJECTIVES

To provide an updated review of HIIT poststroke through ( a) synthesizing current evidence; ( b) proposing preliminary considerations of HIIT parameters to optimize benefit; ( c) discussing potential mechanisms underlying changes in function, cardiovascular health, and neuroplasticity following HIIT; and ( d) discussing clinical implications and directions for future research.

RESULTS

Preliminary evidence from 10 studies report HIIT-associated improvements in functional, cardiovascular, and neuroplastic outcomes poststroke; however, optimal HIIT parameters remain unknown.

CONCLUSION

Larger randomized controlled trials are necessary to establish ( a) effectiveness, safety, and optimal training parameters within more heterogeneous poststroke populations; (b) potential mechanisms of HIIT-associated improvements; and ( c) adherence and psychosocial outcomes.

Longer Work/Rest Intervals During High-Intensity Interval Training (HIIT) Lead to Elevated Levels of miR-222 and miR-29c

Aim: MicroRNA-222 (miR-222) and miR-29c have been identified as important modulators of cardiac growth and may protect against pathological cardiac remodeling. miR-222 and -29c may thus serve as functional biomarkers for exercise-induced cardiac adaptations. This investigation compared the effect of two workload-matched high-intensity interval training (HIIT) protocols with different recovery periods on miR-222 and -29c levels.

Methods: Sixty-three moderately trained females and males (22.0 ± 1.7 years) fulfilled the eligibility criteria and were randomized into two HIIT groups using sex and exercise capacity. During a controlled 4-week intervention (two sessions/week) a 4 × 30 HIIT group performed 4 × 30 s runs (all-out, 30 s active recovery) and a 8 × 15 HIIT group performed 8 × 15 s runs (all-out, 15 s active recovery). miR-222 and -29c as well as transforming growth factor-beta1 (TGF-beta1) mRNA levels were determined during high-intensity running as well as aerobic exercise using capillary blood from earlobes. Performance parameters were assessed using an incremental continuous running test (ICRT) protocol with blood lactate diagnostic and heart rate (HR) monitoring to determine HR recovery and power output at individual anaerobic threshold (IAT).

Results: At baseline, acute exercise miR-222 and -29c levels were increased only in the 4 × 30 HIIT group (both p < 0.01, pre- vs. post-exercise). After the intervention, acute exercise miR-222 levels were still increased in the 4 × 30 HIIT group (p < 0.01, pre- vs. post-exercise) while in the 8 × 15 HIIT group again no acute effect was observed. However, both HIIT interventions resulted in elevated resting miR-222 and -29c levels (all p < 0.001, pre- vs. post-intervention). Neither of the two miRNAs were elevated at any ICRT speed level at baseline nor follow-up. While HR recovery was improved by >24% in both HIIT groups (both p ≤ 0.0002) speed at IAT was improved by 3.6% only in the 4 × 30 HIIT group (p < 0.0132). Correlation analysis suggested an association between both miRNAs and TGF-beta1 mRNA (all p ≤ 0.006, r ≥ 0.74) as well as change in speed at IAT and change in miR-222 levels (p = 0.024, r = 0.46).

Conclusions: HIIT can induce increased circulating levels of cardiac growth-associated miR-222 and -29c. miR-222 and miR-29c could be useful markers to monitor HIIT response in general and to identify optimal work/rest combinations.

EX-MET study: exercise in prevention on of metabolic syndrome - a randomized multicenter trial: rational and design

Background

Metabolic syndrome substantially increases risk of cardiovascular events. It is therefore imperative to develop or optimize ways to prevent or attenuate this condition. Exercise training has been long recognized as a corner-stone therapy for reducing individual cardiovascular risk factors constituting the metabolic syndrome. However, the optimal exercise dose and its feasibility in a real world setting has yet to be established.

The primary objective of this randomized trial is to investigate the effects of different volumes of aerobic interval training (AIT) compared to the current exercise guideline of moderate-intensity continuous training (MICT) on the composite number of cardiovascular disease risk factors constituting the metabolic syndrome after a 16 week, 1-year, and 3-year follow-up.

Methods

This is a randomized international multi-center trial including men and women aged ≥30 years diagnosed with the metabolic syndrome according to the International Diabetes Federation criteria. Recruitment began in August 2012 and concluded in December 2016. This trial consists of supervised and unsupervised phases to evaluate the efficacy and feasibility of different exercise doses on the metabolic syndrome in a real world setting. This study aims to include and randomize 465 participants to 3 years of one of the following training groups: i) 3 times/week of 4 × 4 min AIT at 85–95% peak heart rate (HRpeak); ii) 3 times/week of 1 × 4 min AIT at 85–95% HRpeak; or iii) 5–7 times/week of ≥30 min MICT at 60–70% HRpeak. Clinical examinations, physical tests and questionnaires are administered to all participants during all testing time points (baseline, 16 weeks and after 1-, and 3-years).

Discussion

This multi-center international trial indeed aims to ease the burden in healthcare/economic cost arising from treating end-stage CVD related conditions such as stroke and myocardial infarction, that could eventually emerge from the metabolic syndrome condition.

Trial registration

Clinical registration number: NCT01676870, ClinicalTrials.gov (August 31, 2012).