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

BACKGROUND

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Flexible insulin therapy with a hybrid regimen of insulin degludec and continuous subcutaneous insulin infusion with pump suspension before exercise in physically active adults with type 1 diabetes (FIT Untethered): a single-centre, open-label, proof-of-concept, randomised crossover trial

BACKGROUND

People with type 1 diabetes who use continuous subcutaneous insulin infusion (CSII, or insulin pump therapy) often remove their pump before extended periods of exercise, but this approach might result in reduced glycaemic control and increased risk of hyperglycaemia and ketogenesis. We aimed to assess the efficacy and safety of a hybrid approach, in which basal insulin delivery was divided between CSII and a daily injection of insulin degludec.

METHODS

In this single-centre, open-label, proof-of-concept, randomised crossover trial done at the LMC Diabetes & Endocrinology research centre, we recruited physically active and aerobically fit participants aged 18 years or older with type 1 diabetes who were using CSII. Participants were randomly assigned (1:1) by use of a computer-generated sequence to one of two sequences of either usual CSII, involving the continuation of the participant's usual CSII regimen, followed by crossover to hybrid CSII, in which the delivery of the participant's usual daily basal insulin dose was split (50% delivered by CSII and 50% delivered by a once-daily morning injection of 100 U/mL insulin degludec), or the opposite sequence (ie, hybrid CSII followed by crossover to usual CSII). Treatment was not masked to the investigators or participants. For each intervention, participants completed a moderate-intensity and a high-intensity in-clinic exercise session in the first week, followed by four high-intensity and two moderate-intensity home-based exercise sessions in the subsequent 3 weeks. Insulin pumps were suspended or disconnected 60 min before exercise and reconnected immediately after exercise during both treatment regimens. The coprimary outcomes were: (1) time spent in the target control range of 4·0-10·0 mmol/L blood glucose after high-intensity exercise, and (2) time spent in target control range of 4·0-10·0 mmol/L blood glucose after moderate-intensity exercise, measured by continuous glucose monitoring in the 6-h period from the start of the high-intensity and moderate-intensity in-clinic exercise sessions. Outcomes were assessed in a modified intention-to-treat population that included all participants who started both intervention phases and completed all of the in-clinic exercise visits. This trial is registered with ClinicalTrials.gov, NCT03838783, and is complete.

FINDINGS

Between May 15, 2018, and March 5, 2019, we assessed 43 patients for eligibility, of whom 31 were randomly assigned to receive the usual CSII regimen (n=14) or hybrid CSII regimen (n=17) in the first phase (before crossover). The analysis population consisted of 24 participants who completed both study phases. Compared with the usual CSII regimen, participants on the hybrid CSII regimen had a significantly longer time in blood glucose range of 4-10 mmol/L during the 6-h period from the start of both moderate-intensity (mean difference 86 min [95% CI 61-147], p=0·005; percentage time in range 64% [SD 35] vs 40% [35]) and high-intensity in-clinic exercise session (60 min [11-109], p=0·01; 66% [32] vs 50% [27]). Participants on the hybrid CSII regimen also showed a higher time in blood glucose range of 4-10 mmol/L during home-based exercise sessions (mean difference 23 min [95% CI -1 to 46], p=0·055), with significantly lower time spent in hyperglycaemia than participants on the usual CSII regimen (mean difference 25 min [2-48], p=0·04). These exploratory outcomes also showed no significant difference in the amount of time spent in hypoglycaemia, nor the number of hypoglycaemic events, between the two interventions. There were three study-related adverse events reported with the usual CSII regimen (two hypotension events and one nausea event) and four with the hybrid CSII regimen (two hypotension events and two nausea events).

INTERPRETATION

A hybrid regimen of injected insulin degludec and CSII (with pump removal during exercise) appears to be safe and effective in adults with type 1 diabetes who exercise regularly. This approach could offer improved glycaemic control immediately after exercise and should be further assessed in a larger-scale randomised trial.

FUNDING

Novo Nordisk.

Influence of daily beer or ethanol consumption on physical fitness in response to a high-intensity interval training program. The BEER-HIIT study

BACKGROUND

High-intensity interval training (HIIT) is an effective approach to improve physical fitness, but consuming beer, which is a regular practice in many physically active individuals, may interfere with these effects. The purposes of this study were to investigate the effects of a 10-week (2 days/week) HIIT program on cardiorespiratory fitness, muscle strength and power parameters, and also to assess the possible influence on them of a moderate consumption of beer (at least from Monday to Friday) or its alcohol equivalent.

METHODS

Young (24 ± 6 years old) healthy adults (n = 73, 35 females) were allocated to five groups. Four groups participated in the HIIT intervention program while the fifth group was a control Non-Training group (n = 15). Participants in the training groups chose whether they preferred receiving alcohol or alcohol-free beverages. Those choosing alcohol were randomized to either beer or ethanol intake: (i) T-Beer group (alcohol beer, 5.4%; n = 13) or (ii) T-Ethanol (sparkling water with vodka, 5.4%; n = 14). Those choosing alcohol-free intake were randomized to (iii) T-Water group (sparkling water, 0.0%; n = 16), or (iv) T-0.0Beer group (alcohol-free beer, 0.0%; n = 15). Men ingested 330 ml of the beverage at lunch and 330 ml at dinner; women ingested 330 ml at dinner. Before and after the intervention, maximal oxygen uptake in absolute and relative terms (VO2max.), maximal heart rate, total test duration, hand grip strength and four types of vertical jumps were measured.

RESULTS

HIIT induced significant improvements in absolute and relative values of VO2max, and total test duration (all p < 0.05) in all the training groups; also, clinical improvements were found in hand grip strength. These positive effects were not influenced by the regular intake of beer or alcohol. No changes in the vertical jumps occurred in any of the groups.

CONCLUSIONS

A moderate beer or alcohol intake does not mitigate the positive effect of a 10-week HIIT on physical fitness in young healthy adults.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT03660579. Registered 20 September 2018. Retrospectively registered.

Relationship between maximal incremental and high-intensity interval exercise performance in elite athletes

This descriptive study aimed to explore the physiological factors that determine tolerance to exertion during high-intensity interval effort. Forty-seven young women (15–28 years old) were enrolled: 23 athletes from Taiwan national or national reserve teams and 24 moderately active females. Each participant underwent a maximal incremental INC (modified Bruce protocol) cardiopulmonary exercise test on the first day and high-intensity interval testing (HIIT) on the second day, both performed on a treadmill. The HIIT protocol involved alternation between 1-min effort at 120% of the maximal speed, at the same slope reached at the end of the INC, and 1-min rest until volitional exhaustion. Gas exchange, heart rate (HR), and muscle oxygenation at the right vastus lateralis, measured by near-infrared spectroscopy, were continuously recorded. The number of repetitions completed (R_lim) by each participant was considered the HIIT tolerance index. The results showed a large difference in the R_lim (range, 2.6–12.0 repetitions) among the participants. Stepwise linear regression revealed that the variance in the R_lim within the cohort was related to the recovery rates of oxygen consumption (V˙O2), HR at the second minute after INC, and muscle tissue saturation index at exhaustion (R = 0.644). In addition, age was linearly correlated with R_lim (adjusted R = −0.518, p < 0.0001). In conclusion, the recovery rates for V˙O2 and HR after the incremental test, and muscle saturation index at exhaustion, were the major physiological factors related to HIIT performance. These findings provide insights into the role of the recovery phase after maximal INC exercise testing. Future research investigating a combination of INC and HIIT testing to determine training-induced performance improvement is warranted.

Rejuvenation of Neutrophil Functions in Association With Reduced Diabetes Risk Following Ten Weeks of Low-Volume High Intensity Interval Walking in Older Adults With Prediabetes - A Pilot Study

Neutrophil dysfunction is a common feature of aging, and is associated with the pathogenesis of many age-related diseases, including type 2 diabetes mellitus (T2DM). Although exercise training improves metabolic health, decreases risk of T2DM, and is associated with improving neutrophil functions, involvement in regular physical activity declines with age. The aim of this study was to determine if neutrophil functions could be improved in association with changes in fitness and metabolic parameters in older adults at risk for T2DM using 10-weeks of low volume high-intensity interval exercise training (HIIT). Ten older (71 ± 5 years) sedentary adults with prediabetes (HbA1c: 6.1 ± 0.3%) completed 10 weeks of a supervised HIIT program. Three 30 min sessions/week consisted of ten 60 s intervals of low intensity [50-60% heart rate reserve (HRR)] separated with similar durations of high intensity intervals (80-90% HRR). Before and after training, glucose and insulin sensitivity, neutrophil chemotaxis, bacterial phagocytosis, reactive oxygen species (ROS) production, and mitochondrial functions were assessed. Exercise-mediated changes in cardiorespiratory fitness (VO2peak) and neutrophil functions were compared to six young (23 ± 1 years) healthy adults. Following training, significant reductions in fasting glucose and insulin were accompanied by improved glucose control and insulin sensitivity (all p < 0.05). Before exercise training, VO2peak in the old participants was significantly less than that of the young controls (p < 0.001), but increased by 16 ± 11% following training (p = 0.002) resulting in a 6% improvement of the deficit. Neutrophil chemotaxis, phagocytosis and stimulated ROS production were significantly less than that of the young controls, while basal ROS were higher before training (all p < 0.05). Following training, chemotaxis, phagocytosis and stimulated ROS increased while basal ROS decreased, similar to levels observed in the young controls (all p < 0.05) and reducing the deficit of the young controls between 2 and 154%. In five of the adults with prediabetes, neutrophil mitochondrial functions were significantly poorer than the six young controls before training. Following training, mitochondrial functions improved toward those observed in young controls (all p < 0.05), reducing the deficit of the young controls between 14.3 and 451%. Ten weeks of HIIT in older adults at risk for T2DM reduced disease risk accompanied by improved primary and bioenergetic neutrophil functions. Our results are consistent with a reduced risk of infections mediated by relationships in exercise induced systemic and cellular metabolic features. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02441205, registered on May 12th, 2015.

Identifying facilitators and barriers for adolescents participating in a school-based HIIT intervention: the eXercise for asthma with commando Joe's® (X4ACJ) programme

BACKGROUND

High-intensity interval training (HIIT) elicits numerous health benefits, but little evidence is available regarding the feasibility of delivering school-based HIIT interventions. The aim of this study was to explore adolescents' perceptions of a 6-month, 3 × 30-min sessions per week, HIIT intervention delivered either before or after school.

METHOD

Eighty adolescents allocated to the intervention group (13.3 ± 1.0 years; 45 boys) were invited to take part in semi-structured focus groups post-intervention. Participants were categorised as attendees (≥40% attendance) or non-attendees (< 5% attendance). Data were transcribed verbatim and thematically analysed deductively, with key emergent themes represented using pen profiles.

RESULTS

Results showed that a school-based HIIT intervention can be an enjoyable form of exercise. Irrespective of attendance, similar facilitators and barriers to participating were highlighted, including benefits of participation, content of the exercise session and the intervention instructor.

CONCLUSION

This study provides support for the delivery of a HIIT intervention in a school setting but highlights the importance of a flexible design and delivery to accommodate competing interests. There is a need to educate adolescents on the possible benefits of participation and to make the sessions enjoyable in order to increase their extrinsic and intrinsic motivation to sustain participation.

Comparable blood velocity changes in middle and posterior cerebral arteries during and following acute high-intensity exercise in young fit women

The cerebral blood flow response to high-intensity interval training (HIIT) remains unclear. HIIT induces surges in mean arterial pressure (MAP), which could be transmitted to the brain, especially early after exercise onset. The aim of this study was to describe regional cerebral blood velocity changes during and following 30 s of high-intensity exercise. Ten women (age: 27 ± 6 years; VO2max : 48.6 ± 3.8 ml·kg·min-1 ) cycled for 30 s at the workload reached at V ˙ O2max followed by 3min of passive recovery. Middle (MCAvmean ) and posterior cerebral artery mean blood velocities (PCAvmean ; transcranial Doppler ultrasound), MAP (finger photoplethysmography), and end-tidal carbon dioxide partial pressure (PET CO2 ; gaz analyzer) were measured. MCAvmean (+19 ± 10%) and PCAvmean (+21 ± 14%) increased early after exercise onset, returning toward baseline values afterward. MAP increased throughout exercise (p < .0001). PET CO2 initially decreased by 3 ± 2 mmHg (p < .0001) before returning to baseline values at end-exercise. During recovery, MCAvmean (+43 ± 15%), PCAvmean (+42 ± 15%), and PET CO2 (+11 ± 3 mmHg; p < .0001) increased. In young fit women, cerebral blood velocity quickly increases at the onset of a 30-s exercise performed at maximal workload, before returning to baseline values through the end of the exercise. During recovery, cerebral blood velocity augments in both arteries, along with PET CO2 .

Effect of somatic maturity on the aerobic and anaerobic adaptations to sprint interval training

The purpose of this study was to assess the maturity-related differences in the aerobic and anaerobic adaptations to sprint interval training (SIT) among youth male athletes. Twenty-seven youth male athletes were assessed for years from peak height velocity (PHV) and classified into prepubescent (PRE, n = 7, years from PHV = -2.21 ± 0.47 years), peripubescent (PERI, n = 10, years from PHV = 0.25 ± 0.88 years), and postpubescent (POST, n = 10, years from PHV = 2.81 ± 0.50 years) groups based on their years from estimated peak height velocity. Participants completed a ramp exercise protocol on a cycle ergometer to determine maximal aerobic power, maximal oxygen consumption (VO2peak ), and fatigue thresholds. Following baseline, all participants completed a 4-week SIT program that consisted of eight total training sessions. During each session, participants completed repeated 20-s sprints on a cycle ergometer against a resistance of 7.5% of body mass. The number of sprints per sessions increased from four in session 1 to seven in session 7, with four sprints in session 8. Peak and mean power from sessions 1 and 8 were recorded. All participants completed a post-testing ramp exercise protocol that mirrored baseline. Maximal aerobic power increased (p < .001) across all groups from baseline (212.61 ± 57.45 W) to post-testing (223.24 ± 58.90 W); however, VO2peak only increased in POST (3.31 ± 0.43 to 3.54 ± 0.43 L min-1 , p = .003). Similarly, GET, VT, and RCP increased in POST, with no changes in PRE or PERI. In terms of anaerobic performance, PERI and POST had significant increases in peak and mean power. POST improved aerobic and anaerobic performance following SIT, while PERI only experienced improvements in anaerobic performance. Conversely, PRE had no changes in aerobic or anaerobic performance. The adaptations to SIT appear to be influenced by the somatic maturity status.

High-intensity exercise training improves perioperative risk stratification in the high-risk patient

Exercise prehabilitation prior to major surgery can improve cardiorespiratory fitness (CRF) and clinical outcome. However, in patients deemed "high--risk" for surgery, the feasibility, optimum training modality and its intensity, duration, and frequency are yet to be defined. We assessed the cardiorespiratory fitness of a 70-year-old female patient requiring major thoraco-abdominal surgery for reconstruction of her esophagus. Cardiopulmonary exercise testing (CPET) on a cycle ergometer was used to determine CRF. A baseline CPET confirmed poor CRF and placed her in a high surgical risk group. This was followed by 16 weeks of unsupervised, home-based, moderate-intensity steady-state (MISS) training followed by 10 weeks of high-intensity interval training (HIIT) under the combined supervision of an exercise physiologist and clinician in hospital. Following MISS training, CPET metrics failed to improve: peak oxygen uptake decreased (14.7-13.7 ml O2 ·kg-1 ·min-1 ; -7%) together with peak power (73-70 W; -4%) and anaerobic threshold (AT) increased (7.8-8.3 ml O2 ·kg-1 ·min-1 ; +6%). However, HIIT resulted in impressive improvement in CRF. Peak oxygen uptake (13.7-18.6 ml O2 ·kg-1 ·min-1 ; +36%), AT (8.3-10.5 ml O2 ·kg-1 ·min-1 ; +27%), peak power (70-102 W; +46%), minute ventilation (35.8-57.7 L·min-1 ; +61%), and peak heart rate (100-133 b·min-1 ; +33%) all increased. Ventilatory equivalents for carbon dioxide at AT ( V ˙ E / V ˙ CO2 -AT) improved (30-28; -7%). The improvement in CRF resulted in surgical reclassification from high to low risk. In conclusion, preoperative HIIT training can confer a marked improvement in CRF in an elderly surgical patient and is associated with a corresponding reduction in perioperative risk.

Effect of High Intensity Interval Training on Matrix Metalloproteinases in Women with Breast Cancer Receiving Anthracycline-Based Chemotherapy

Anthracycline chemotherapy is commonly used to treat breast cancer yet may increase the level of matrix metalloproteinases (MMP) -2 and -9, which increase the risk of atherosclerosis. While exercise has been shown to reduce the level of MMP in patients with diabetes, high intensity interval training (HIIT) has not been utilized to improve level of MMP in women with breast cancer receiving anthracycline chemotherapy. Thirty women were randomized to either 8-week HIIT or control (CON) group. The CON group was offered the HIIT intervention after 8 weeks. MMP-1, -2 -7, -9, tissue inhibitor of MMP (TIMP) -1, and-2 were measured at baseline and post-intervention. Repeated measures ANCOVA and paired t-test were performed to assess changes in MMP and TIMP. Post-intervention, no significant between-group differences were observed for MMP and TIMP. However, within-group decrease in MMP-9 was observed in the HIIT group [104.3(51.9) to 65.2(69.1); P = 0.01]. MMP-9 in the CON group was not significantly changed [115.5(47.2) to 90.4(67.9);]. MMP-2 significantly increased in both the HIIT group [76.6(11.2) to 83.2(13.1); P = 0.007) and the CON group [69.0(8.9) to 77.6(11.1) P = 0.003). It is unclear whether an 8-week HIIT intervention influences MMP-9 in breast cancer patients undergoing anthracycline chemotherapy. Additional investigations are required to understand the exercise-induced changes in MMP-2 and -9 in women undergoing anthracycline chemotherapy.

Exercise Training Adaptations in Metabolic Syndrome Individuals on Chronic Statin Treatment

BACKGROUND

Statins reduce atherogenic dyslipidemia and cardiovascular disease (CVD) risk in metabolic syndrome (MetS) individuals. Exercise training could also contribute to reduce CVD by improving cardiorespiratory fitness and fat oxidation. However, statin use could interfere with training adaptations.

METHODS

A total of 106 MetS individuals were divided into statin users (statin group, n = 46) and statin-naïve (control group, n = 60). Groups were matched by age, weight, and MetS components. Subjects completed 16 weeks of high intensity interval training (HIIT). Before and after HIIT, muscle biopsies were collected to assess mitochondrial content (citrate synthase [CS] activity) and the activity of the rate limiting β-oxidation enzyme (3-hydroxyacyl-CoA-dehydrogenase [HAD]). Fasting plasma glucose, insulin, TG, HDL-c, and LDL-c concentrations were measured. Exercise maximal fat oxidation (FOMAX) and oxygen uptake (VO2PEAK) were determined.

RESULTS

Training improved MetS similarly in both groups (MetS z-score -0.26 ± 0.38 vs. -0.22 ± 0.31; P < 0.001 for time and P = 0.60 for time x group). Before training, the statin group had reduced muscle HAD activity and whole body FOMAX compared to the control group. However, 16 weeks of HIIT increased HAD and FOMAX in both groups (P < 0.03, time-effect). The statin group did not prevent the increases in CS with HIIT observed in the control group (38% vs 64%, respectively; P < 0.001, time-effect). Conversely, with training VO2PEAK improved less in the statin than in the control group (12% vs. 19%, respectively; P = 0.013, time × group effect).

CONCLUSION

Chronic statin use in MetS does not interfere with exercise training improvements in MetS components, FOMAX, or mitochondrial muscle enzymes (ie, CS and HAD). However, the statin group attenuated the improvements in VO2PEAK with training.

CLINICAL TRIAL INFORMATION

ClinicalTrials.gov identifier no. NCT03019796, January 13, 2017.

Effects of High-Intensity Interval Training After Stroke (the HIIT-Stroke Study): A Multicenter Randomized Controlled Trial

OBJECTIVE

To examine if 8 weeks of high-intensity interval training (HIIT) in addition to standard care would increase and maintain peak oxygen uptake (Vo_2peak) more than standard care alone in patients with stroke.

DESIGN

This was a single-blind, multicenter, parallel group, randomized controlled trial.

SETTING

Specialized rehabilitation units at 3 Norwegian hospitals.

PARTICIPANTS

Participants (N=70), 3 months to 5 years after first-ever stroke, were randomly assigned to the intervention group (n=36) or the control group (n=34); 42% were women, mean age was 57.6±9.3 years, mean time post stroke was 26.4±14.5 months.

INTERVENTION

The intervention was 8 weeks: 3 times a week with HIIT treadmill training with work periods of 4 × 4 minutes at 85%-95% of peak heart rate interspersed with 3 minutes of active recovery at 50%-70% of peak heart rate. The control group received standard care according to national guidelines.

OUTCOMES

The primary outcome, analyzed by intention-to-treat, was Vo_2peak measured as liters per minute 12 months after inclusion. Secondary outcome measures were blood pressure and blood profile.

RESULTS

Mean baseline Vo_2peak was 2.63±1.08 L·min^-1 vs 2.87±0.71 L·min^-1, while at 12 months Vo_2peak was 2.70±1.00 L·min^-1 vs 2.67±0.76 L·min^-1 (P=.068) in the intervention and control groups, respectively. There was a significant and greater improvement in the intervention group compared with the control group at 12 months in 3 of 6 secondary outcomes from the peak test but no significant differences for blood pressure or blood profile.

CONCLUSIONS

The HIIT intervention, which was well-tolerated in this sample of well-functioning survivors of stroke, was not superior to standard care in improving and maintaining Vo_2peak at the 12-month follow-up. However, secondary results from the peak test showed a significant improvement from before to immediately after the intervention.

Five Weeks of Aquatic-Calisthenic High Intensity Interval Training Improves Cardiorespiratory Fitness and Body Composition in Sedentary Young Adults

Aquatic exercise may be better tolerated by sedentary, overweight individuals than land-based exercise. The purpose of the present study was to determine the effects of five weeks of aquatic high-intensity interval training (AHIIT) using standard calisthenic pool exercises, on cardiorespiratory fitness and body composition in sedentary young adults. Eleven college-age participants (9 women, 2 men) completed 15 exercise sessions that included three sessions per week for five weeks. Each session consisted of a five-minute warm-up period, 25 minutes of exercise, and a five-minute cool down. A training progression based upon standard progression principals from a pilot study was implemented. The exercises consisted of 25 exercise intervals lasting 10-30 seconds in duration, utilizing combinations of 8-12 different exercises. Twenty-two standard aquatic upper body, lower body, and full body aerobic exercises, most of which utilized aquatic dumbbells or hand paddles, were performed in an AHIIT protocol during each exercise session. Reductions in body composition (32.6 to 30.6% fat), submaximal (169 to 165 b·min^-1) and peak heart rate (199 to 192 b·min^-1), submaximal VO₂ (21.7 to 19.3 ml·kg^-1·min^-1 and peak VO₂ (30.5 to 31.95 ml·kg^-1·min^-1) occurred from pre- to post-program. This is the first study to determine the effectiveness of standard aquatic calisthenic exercises used in an AHIIT protocol. Improvements in cardiorespiratory fitness and exercise economy as well as body composition were observed in these sedentary individuals.

High-intensity interval exercise and hypoglycaemia minimisation in adults with type 1 diabetes: A randomised cross-over trial

AIMS

We aimed to examine the feasibility and safety of undertaking high-intensity interval exercise (HIIE) with evening basal insulin dose reduction on exercise-related hypoglycaemia following an afternoon bout of HIIE, compared with moderate-intensity continuous exercise and a non-exercise control day in adults with type 1 diabetes in a free-living environment.

METHODS

Twelve adults with type 1 diabetes participated in a randomised, crossover trial (9 female/3 male, mean age 40.4 ± 9.9 years, duration 16.5 ± 9.8 years, HbA1c 8.0 ± 0.8%). Each participant undertook five conditions: a non-exercise day, and four exercise conditions on separate afternoons: a moderate-intensity continuous exercise bout; and three HIIE bouts with 10%, 20% and 30% evening basal insulin reduction. Post-exercise glucose response was measured for 24 h by continuous glucose monitoring and compared across conditions.

RESULTS

HIIE with 10%, 20% and 30% evening basal insulin dose reduction was not associated with an increase in hypoglycaemia compared with moderate-intensity continuous exercise, or the non-exercise day. There was no difference in hyperglycaemia, time-in-range or glucose variability across all exercise regimens and the non-exercise day (p > .05).

CONCLUSIONS

Exercise-related hypoglycaemia was not increased following afternoon HIIE when diabetes management strategies incorporating evening basal insulin dose reduction were utilised.

Comparative effects of two heat acclimation protocols consisting of high-intensity interval training in the heat on aerobic performance and thermoregulatory responses in exercising rats

Acclimation resulting from low- to moderate-intensity physical exertion in the heat induces several thermoregulatory adaptations, including slower exercise-induced increases in core body temperature. However, few studies have investigated the thermoregulatory adaptations induced by high-intensity interval training (HIIT) protocols. Thus, the present study aimed to compare the adaptations in rats’ thermoregulatory parameters and aerobic performance observed after two different heat acclimation regimens consisting of HIIT protocols performed in a hot environment. Twenty-three adult male Wistar rats were initially subjected to an incremental-speed exercise at 32°C until they were fatigued and then randomly assigned to one of the following three heat acclimation strategies: passive heat exposure without any exercise (untrained controls–UN; n = 7), HIIT performed at the maximal aerobic speed (HIIT_100%; n = 8) and HIIT performed at a high but submaximal speed (HIIT_85%; n = 8). Following the two weeks of interventions, the rats were again subjected to a fatiguing incremental exercise at 32°C, while their colonic temperature (T_COL) was recorded. The workload performed by the rats and their thermoregulatory efficiency were calculated. After the intervention period, rats subjected to both HIIT protocols attained greater workloads (HIIT_100%: 313.7 ± 21.9 J vs. HIIT_85%: 318.1 ± 32.6 J vs. UN: 250.8 ± 32.4 J; p < 0.01) and presented a lower ratio between the change in T_COL and the distance travelled (HIIT_100%: 4.95 ± 0.42°C/km vs. HIIT_85%: 4.33 ± 0.59°C/km vs. UN: 6.14 ± 1.03°C/km; p < 0.001) when compared to UN rats. The latter finding indicates better thermoregulatory efficiency in trained animals. No differences were observed between rats subjected to the two HIIT regimens. In conclusion, the two HIIT protocols induce greater thermoregulatory adaptations and performance improvements than passive heat exposure. These adaptations do not differ between the two training protocols investigated in the present study.

The effectiveness of high-intensity interval training on body composition, cardiorespiratory fitness, and cardiovascular risk factors in children: A protocol for a systematic review

BACKGROUND

No previous systematic review has examined the effect of high-intensity interval training (HIIT) interventions on body composition, cardiometabolic risk factors and cardiorespiratory fitness (CRF) in healthy schoolchildren from 5 to 12 years old.

METHODS

This study will be conducted by following the guideline of the preferred reporting items for systematic review and meta-analysis protocols. An electronic search in MEDLINE (via PubMed), EMBASE (via Scopus), SPORTDiscus, Cochrane Library and Web of Science databases of all dates from inception will be conducted. We will include randomized controlled trials aimed to assess the effectiveness of HIIT to improve cardiometabolic risk factors, body composition, and CRF in children. Two authors will perform the study selection and data collection; disagreements will be solved by a third reviewer. The methodological quality of studies will be assessed by the Cochrane Collaboration's tool for assessing risk of bias (RoB2). Data analysis and synthesis will be performed by Comprehensive Meta-analysis Software and StataSE software, version 15.

CONCLUSION

The results should be disseminated through publication in a peer-reviewed journal. Since the data used in systematic reviews of this type will be extracted exclusively from published studies, approval form and ethics committee will not be required.

High Intensity Interval training (HIIT) for people with severe mental illness: A systematic review & meta-analysis of intervention studies- considering diverse approaches for mental and physical recovery

There is a mortality gap of 15 to 20 years for people with severe mental illness (SMI - psychotic spectrum, bipolar, major depressive disorders). Modifiable risk factors include inactivity and low cardiorespiratory fitness (CRF). Exercise can improve mental and physical outcomes; optimal type and intensity of exercise for people with SMI has yet to be determined. High Intensity Interval training (HIIT) is an exercise with distinct cardio-metabolic advantages in other disease populations compared to traditional moderate intensity continuous training (MCT). We investigated the feasibility and efficacy of HIIT for people with SMI. Major electronic databases were searched, identifying HIIT studies for adults experiencing SMI.Data on feasibility, safety, study design, sample characteristics, and physical and psychological outcomes were extracted and systematically reviewed. Meta-analyses were conducted within group, pre and post HIIT interventions, and between group, to compare HIIT with control conditions. Nine articles were identified including three pre/post studies, one non randomised and five randomised trials, (366 participants, 45.1% female). HIIT appears as feasible as MCT, with few safety concerns. Following HIIT, there was a moderate improvement in CRF and depression. There was no difference between HIIT and MCT for adherence or CRF.HIIT improved depression more than MCT.

High-intensity interval training induced PGC-1∝ and AdipoR1 gene expressions and improved insulin sensitivity in obese individuals

INTRODUCTION

High-intensity interval training (HIIT) has been found to improve cardiometabolic health outcome as compared to moderate-intensity continuous exercise. However, there is still limited data on the benefits of HIIT on the expression of regulatory proteins that are linked to skeletal muscle metabolism and insulin sensitivity in obese adults. This study investigated the effects of HIIT intervention on expressions of peroxisome proliferatoractivated receptor-γ coactivator 1-∝ (PGC-1∝) and adiponectin receptor-1 (AdipoR1), insulin sensitivity (HOMAIR index), and body composition in overweight/obese individuals.

METHODS

Fifty overweight/obese individuals aged 22-29 years were assigned to either no-exercise control (n=25) or HIIT (n=25) group. The HIIT group underwent a 12-week intervention, three days/week, with intensity of 65-80% of age-based maximum heart rate. Anthropometric measurements, homeostatic model of insulin resistance (HOMA-IR) and gene expression analysis were conducted at baseline and post intervention.

RESULTS

Significant time-by-group interactions (p<0.001) were found for body weight, BMI, waist circumference and body fat percentage. The HIIT group had lower body weight (2.3%, p<0.001), BMI (2.7%, p<0.001), waist circumference (2.4%, p<0.001) and body fat percentage (4.3%, p<0.001) post intervention. Compared to baseline, expressions of PGC-1∝ and AdipoR1 were increased by approximately three-fold (p=0.019) and two-fold (p=0.003) respectively, along with improved insulin sensitivity (33%, p=0.019) in the HIIT group.

CONCLUSION

Findings suggest that HIIT possibly improved insulin sensitivity through modulation of PGC-1∝ and AdipoR1. This study also showed that improved metabolic responses can occur despite modest reduction in body weight in overweight/obese individuals undergoing HIIT intervention.

Anthropometric, Cardiopulmonary and Metabolic Benefits of the High-Intensity Interval Training Versus Moderate, Low-Intensity or Control for Type 2 Diabetes: Systematic Review and Meta-Analysis

Abstract: This study aims to evaluate the effectiveness of high-intensity interval training compared with no intervention and other types of training interventions for people with Type 2 Diabetes. A systematic review and meta-analysis of randomized controlled trials that used high-interval intensity training to improve anthropometric, cardiopulmonary and metabolic conditions were conducted. The search was performed during October-December 2017 using the databases PubMed, Web of Science and Physiotherapy Evidence Database (PEDro). The methodological quality of the studies was evaluated using the PEDro scale. A total of 10 articles were included in this meta-analysis. After statistical analysis, favorable results were obtained for high-Intensity Interval Training compared with control (non-intervention): [Weight: Standardized mean difference (SMD) = -2.09; confidence interval (CI) 95%: (-3.41; -0.78); body-mass index: SMD = -3.73; CI 95%: (-5.53; -1.93); systolic blood pressure: SMD = -4.55; CI 95%: (-8.44; -0.65); VO2max: SMD = 12.20; CI 95%: (0.26; 24.14); HbA1c: SMD = -3.72; CI 95%: (-7.34; -0.10)], moderate intensity continuous training: [body-mass index: SMD = -0.41; CI 95%: (-0.80; -0.03); VO2max: SMD = 1.91; CI 95%: (0.18; 3.64)], and low intensity training: [Weight: SMD = -2.06; CI 95%: (-2.80; -1.31); body-mass index: SMD = -3.04; CI 95%: (-5.16; -0.92); systolic blood pressure: SMD = -2.17; CI 95%: (-3.93; -0.41); HbA1c: SMD = -1.58; CI 95%: (-1.84; -1.33)]. The results show that high-intensity interval training can be a useful strategy in order to improve anthropometric, cardiopulmonary and metabolic parameters in people with Type 2 diabetes. Despite this, it could be essential to clarify and unify criteria in the intervention protocols, being necessary new lines of research.

Effects of sprint interval training on cardiorespiratory fitness while in a hyperbaric oxygen environment

OBJECTIVES

Hyperbaric oxygen (HBO2) exposure may enhance cardiorespiratory fitness. Exercise training and HBO2 exposure stimulate mitochondrial biogenesis, increase capillary density, and induce adaptive antioxidant mechanisms. We hypothesized that an exercise regimen of sprint interval training (SIT) while breathing HBO2 would lead to a greater improvement in exercise performance compared to the same training breathing ambient air.

METHODS

Healthy long-term intermediate-altitude residents, ages 20-39 years, with normal spirometry and cardiorespiratory fitness were randomized to two groups: one performing six sessions of a SIT regimen over two weeks in a hyperbaric chamber (1.4 ATA [141.9 kPa], FiO2=1.0); the other performing under ambient pressure conditions (0.85 ATA [86.1 kPa], FiO2=0.21). Training effect was evaluated by comparing incremental cycle ergometry cardiopulmonary exercise testing before and after the training regimen. The primary outcome measure was peak oxygen consumption (V̇O2), while secondary outcomes included additional exercise parameters. The effect of study group on exercise parameters was assessed using two-factor repeated measures ANOVA.

RESULTS

Of 58 participants randomized, 49 completed the training program and all cardiopulmonary exercise tests (n=23 HBO2, n=26 ambient). Both groups experienced an increase in peak V̇O2: 8.1% HBO2 and 7.1% ambient; the differences were not significant (p=0.50). Secondary parameters of peak work rate and peak V̇E experienced a significantly higher change in the HBO2 group compared to the ambient group (p=0.05 and p=0.03, respectively).

CONCLUSION

Cardiorespiratory fitness improved after a two-week SIT regimen, but improvement in peak V̇O2 was not significantly different between ambient and HBO2 groups.

Psychophysiological Intervention to Improve Preparedness in Military Special Operations Forces

BACKGROUND: Actual studies in military training support the use of new methodological approaches such as high intensity interval training and inverse periodization training rather than conventional approaches. However, the application and analysis of success of these new methodologies are as yet unknown.METHODS: The military adapted the civil reverse periodization training system, composed of 6 wk and five sessions per week. For the first 3 wk soldiers performed two sessions with the objective of increasing the maximal strength of the upper and lower body muscles, and three sessions of short high-intensity interval training (HIIT). In the following 3 wk they combined two endurance HIIT and two resistance HIIT sessions with military equipment while conducting a military task.RESULTS: After the training a significant body mass index decrease was found, along with an increase in lower limb muscular strength, aerobic and anaerobic performance, resilience, stress tolerance, and psychological flexibility. Regarding the ratio of acceptance there was an increased ratio compared to previous years of 7%. In addition, married soldiers with children presented greater resilience, stress tolerance, psychological flexibility, and a higher ratio of success.DISCUSSION: Accepted soldiers presented greater psychological status and stress tolerance, highlighting the importance of the work of the unit psychologists to reinforce and monitor the psychometric profile of the soldiers as well as their intrinsic characteristics of personality and emotionality. The greater baseline physical condition and higher performance in all physical tests proves how reverse periodization training models are a great stimuli and training approach in soldiers.Tornero-Aguilera JF, Gregório Pelarigo J, Clemente-Suarez VJ. Psychophysiological intervention to improve preparedness in military Special Operations forces. Aerosp Med Hum Perform. 2019; 90(11):953-958.

High-Intensity Interval Circuit Training Versus Moderate-Intensity Continuous Training on Functional Ability and Body Mass Index in Middle-Aged and Older Women: A Randomized Controlled Trial

The literature suggests that high-intensity interval training (HIIT) is more effective than moderate-intensity continuous training (MICT) to improve functional ability. However, there is no evidence on including HIIT in a circuit programme (HIICT). Our objective was to determine what type of training (HIICT or MICT) induces greater adaptations in the functional ability and body mass index of middle-aged and older women. The study used a quasi-experimental randomized controlled trial with 54 participants (age = 67.8 ± 6.2 years). Participants were randomly allocated to HIICT (n = 18), MICT (n = 18) or a non-exercise control group (CG; n = 18). The participants in the HIICT or MICT groups trained twice a week (1 h/session) for 18 weeks. Forty-one subjects were analysed (HIICT; n = 17, MICT; n = 12, CG; n = 12). Five subjects presented adverse events during the study. Strength, gait, cardiorespiratory fitness, balance and body mass index were measured. A significant training x group interaction was found in the arm curl test, where HIICT was statistically better than MICT and CG. Likewise, HIICT was statistically better than the CG in the BMI interaction. In lower limb strength, gait/dynamic balance and cardiorespiratory fitness, both HIICT and MICT were statistically better than the CG. In conclusion, HIICT generated better adaptations in upper limb strength than MICT. Likewise, HIICT generated better adaptations in body mass index than CG. Finally, both HIICT and MICT had a similar influence on strength, cardiorespiratory fitness and gait/dynamic balance.

High-Intensity Interval Training Versus Moderate-Intensity Continuous Training in Middle-Aged and Older Patients with Type 2 Diabetes: A Randomized Controlled Crossover Trial of the Acute Effects of Treadmill Walking on Glycemic Control

Background: This study aimed to compare the acute effects of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on glycemic control in middle-aged and older patients with type 2 diabetes (T2D), using treadmill walking as aerobic exercise mode. Methods: Fifteen patients with T2D (60.25 ± 3.14 years; glycated hemoglobin 7.03 ± 0.33%; medicated with metformin and/or gliptins), participated in a randomized controlled crossover trial. They underwent three experimental conditions (treadmill walking HIIT session (5 × (3 min at 70% of heart rate reserve (HRR) + 3 min at 30% HRR)); treadmill walking MICT session (30 min at 50% HRR); and a control session of rest (CON)) in random order and in the postprandial state. Measurements of capillary blood glucose (BG) were taken immediately before, during, and until 50 min after the experimental conditions. Results: Both HIIT and MICT treadmill walking sessions reduced BG levels during exercise and laboratory 50 min recovery period compared to CON (time*condition interaction effect; p < 0.001). The effect of HIIT was greater compared with MICT (p = 0.017). Conclusions: Treadmill walking HIIT seems a safe and more effective exercise strategy on immediate acute glycemic control compared with MICT in middle-aged and older patients with T2D under therapy with metformin and/or gliptins. Trial Registration Number: ISRCTN09240628.

High-Intensity Interval Training in Cardiac Rehabilitation: Impact on Fat Mass in Patients With Myocardial Infarction

OBJECTIVE

To examine the effect of high-intensity interval training (HIIT) on body fat mass and distribution in patients with myocardial infarction (MI) who underwent cardiac rehabilitation (CR).

PATIENTS AND METHODS

We retrospectively screened 391 consecutive patients with MI enrolled in CR between September 1, 2015, and February 28, 2018. We included 120 patients who completed 36 CR sessions and underwent pretest-posttest dual-energy x-ray absorptiometry; 90 engaged in HIIT, and 30 engaged in moderate-intensity continuous training (MICT). High-intensity interval training included 4 to 8 alternating intervals of high- (30-60 seconds at a rating of perceived exertion [RPE] of 15-17 [Borg scale range, 6-20]) and low-intensity (1-5 minutes at RPE <14), and MICT performed for 20 to 45 minutes of exercise at an RPE of 12 to 14. Body weight, fat mass, and lean mass were measured via dual-energy x-ray absorptiometry with lipid profile measured via clinical procedures.

RESULTS

The HIIT and MICT groups were similar in age (67 vs 67 years), sex (26.7% [24 of 90 patients in the HIIT group] vs 26.7% [8 of 30 in the MICT group), and body mass index (30.3 vs 29.5 kg/m²) at baseline. The HIIT group had greater reductions in body fat percentage (P<.001), fat mass (P<.001), abdominal fat percentage (P<.001), waist circumference (P=.01), total cholesterol (P=.002), low-density lipoprotein cholesterol (P<.001), and triglycerides (P=.006). Improvements in total body mass and body mass index were not different across groups. After matching exercise duration, exercise intensity, and energy expenditure, HIIT-induced improvements in total fat mass (P=.02), body fat percentage (P=.01), and abdominal fat percentage (P=.02) persisted.

CONCLUSION

Our data suggest that supervised HIIT results in significant reductions in total fat mass (P<.001) and abdominal fat percentage (P<.001) and improved lipid profile in patients with MI who undergo CR.

Effects of high-intensity interval training on vascular endothelial function and vascular wall thickness in breast cancer patients receiving anthracycline-based chemotherapy: a randomized pilot study

PURPOSE

The purpose of this study was to determine the effects of an 8-week high-intensity interval training (HIIT) intervention on vascular endothelial function, measured as brachial artery flow-mediated dilation (baFMD), and vascular wall thickness measured by carotid intima media thickness (cIMT) in breast cancer patients undergoing anthracycline-based chemotherapy.

METHODS

Thirty women were randomized to either HIIT or non-exercise control groups (CON). The HIIT group participated in an 8-week HIIT intervention occurring three times per week on a cycle ergometer. The CON group was offered the HIIT intervention after 8 weeks. baFMD was measured from the brachial artery diameter at baseline (D0) and 1 min after cuff deflation (D1); percent change was calculated by measuring brachial artery diameter after cuff deflation relative to the baseline [baFMD = (D1 - D0)/D0 × 100]. The cIMT was obtained from the posterior wall of common carotid artery 10 mm below the carotid bulb. Paired t test and repeated measures ANCOVA were performed to assess changes in baFMD and cIMT.

RESULTS

At baseline, the HIIT (n = 15) and CON (n = 15) groups did not differ by age (46.9 ± 9.8 years), BMI (31.0 ± 7.5 kg/m2), and blood pressure (123.4 ± 16.8/72.3.9 ± 5.6 mmHg). Post-exercise, baFMD significantly increased [4.3; 95% confidence interval (CI): (1.5, 7.0), p = 0.005] in HIIT versus CON group. cIMT did not significantly change [0.003, 95% CI - 0.004, 0.009), p = 0.40] in HIIT group, while IMT significantly increased from baseline to post-intervention (0.009, 95% CI 0.004, 0.010, p = 0.003) in CON group.

CONCLUSION

This study may suggest that HIIT improved vascular endothelial function and maintained wall thickness in breast cancer patients undergoing anthracycline-based chemotherapy.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02454777.