Moderate-intensity Continuous Exercise Training Research Articles

Effects of Short-term Repeated Sprint Exercise Training and Moderate Intensity Continuous Exercise Training on Vascular Function in Healthy Young Adults

Effects of Short-term Repeated Sprint Exercise Training and Moderate Intensity Continuous Exercise Training on Vascular Function in Healthy Young Adults

High-Intensity Interval Versus Moderate-Intensity Continuous Exercise Training on Glycemic Control, Beta Cell Function, and Aerobic Fitness in Women with Type 2 Diabetes.

Objective: This study aimed to compare the effects of High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MICT) on glycemic control, beta-cell function, and aerobic fitness in women with Type 2 Diabetes Mellitus (T2DM). Methods: Thirty-six women with T2DM were assigned equally to HIIT, MICT, and control (CON) groups. Participants in the exercise cohorts underwent a 12-week training regimen (three sessions per week), while the CON group maintained an inactive lifestyle. Glycaemia variables, beta-cell function, maximal oxygen uptake (VO2max), lipid profiles, and body composition were assessed at baseline and post-intervention. Results: Both HIIT and MICT interventions led to significant improvements in glucose, insulin, HbA1c, and insulin resistance index. Moreover, visceral adiposity index (VAI), lipid accumulation product (LAP), total cholesterol (TC), and low-density lipoprotein (LDL) levels significantly decreased in the HIIT and MICT groups after 12 weeks. Triglyceride (TG) levels decreased only after MICT, while high-density lipoprotein (HDL) levels increased after both interventions. Maximal oxygen uptake (VO2max), body mass, body mass index (BMI), and waist circumference (WC) significantly improved in all exercise groups. Notably, the HIIT group showed greater reductions in body mass compared to MICT. Nevertheless, beta-cell function remained unaltered after these two exercise regimens. Conclusion: Both HIIT and MICT interventions effectively managed T2DM in women, regardless of exercise intensity. The HIIT regimen can be considered for time-efficient lifestyle interventions in people with T2DM.

Can In-Task Affect During Interval and Continuous Exercise Predict 12-Month Physical Activity Behavior? Findings from a Randomized Trial.

In-task affective responses to moderate-intensity continuous exercise training (MICT) have been shown to predict future physical activity behavior. However, limited research has investigated whether this affect-behavior relationship is similar for high-intensity interval training (HIIT) and whether it holds true over the longer term. This study aims to determine (1) if in-task affect during 2weeks of supervised MICT and HIIT predicted changes to unsupervised moderate-to-vigorous physical activity (MVPA) behavior 12months post-intervention and (2) if this predictive relationship was moderated by exercise type (MICT vs. HIIT). Ninety-nine adults (69.7% female; 50.9 ± 9.4years) who were low active and overweight were randomized to 2weeks of exercise training of MICT (n = 52) or HIIT (n = 47), followed by 12months of accelerometry-assessed free-living MVPA. The pooled moderation model was not significant, F(3, 94) = 2.54, p = .07 (R2 = 0.085), with a non-significant group by affect interaction (p = .06). The conditional effect for MICT was significant (B = 17.27, t = 2.17, p = .03), suggesting that 12-month change in MVPA increased by 17.27min/week for every one-point increase in in-task affect. The conditional effect for HIIT was not significant (p = .85), suggesting that in-task affect was not predictive of 12-month change in MVPA. The current findings raise important questions about whether the affect-behavior relationship may vary depending on exercise type. For HIIT-based exercise in particular, additional psychological constructs beyond in-task affect should be considered when attempting to predict future physical activity behavior.

High intensity interval training versus moderate intensity continuous training for people with interstitial lung disease: protocol for a randomised controlled trial

BackgroundInterstitial lung disease is a debilitating condition associated with significant dyspnoea, fatigue, and poor exercise tolerance. Pulmonary rehabilitation is an effective and key intervention in people with interstitial lung disease. However, despite the best efforts of patients and clinicians, many of those who participate are not achieving clinically meaningful benefits. This assessor-blinded, multi-centre, randomised controlled trial aims to compare the clinical benefits of high intensity interval exercise training versus the standard pulmonary rehabilitation method of continuous training at moderate intensity in people with fibrotic interstitial lung disease.MethodsEligible participants will be randomised to either a standard pulmonary rehabilitation group using moderate intensity continuous exercise training or high intensity interval exercise training. Participants in both groups will undertake an 8-week pulmonary rehabilitation program of twice-weekly supervised exercise training including aerobic (cycling) and strengthening exercises. In addition, participants in both groups will be prescribed a home exercise program.Outcomes will be assessed at baseline, upon completion of the intervention and at six months following the intervention by a blinded assessor. The primary outcome is endurance time on a constant work rate test. Secondary outcomes are functional capacity (6-min walk distance), health-related quality of life (Chronic Respiratory Disease Questionnaire (CRQ), St George’s Respiratory Questionnaire idiopathic pulmonary fibrosis specific version (SGRQ-I), breathlessness (Dyspnoea 12, Modified Medical Research Council Dyspnoea Scale), fatigue (fatigue severity scale), anxiety (Hospital Anxiety and Depression Scale), physical activity level (GeneActiv), skeletal muscle changes (ultrasonography) and completion and adherence to pulmonary rehabilitation.DiscussionThe standard exercise training strategies used in pulmonary rehabilitation may not provide an optimal exercise training stimulus for people with interstitial lung disease. This study will determine whether high intensity interval training can produce equivalent or even superior changes in exercise performance and symptoms. If high intensity interval training proves effective, it will provide an exercise training strategy that can readily be implemented into clinical practice for people with interstitial lung disease.Trial registration ClinicalTrials.gov Registry (NCT03800914). Registered 11 January 2019, https://clinicaltrials.gov/ct2/show/NCT03800914Australian New Zealand Clinical Trials Registry ACTRN12619000019101. Registered 9 January 2019, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376050&isReview=true

El ejercicio continuo de moderada intensidad es superior al ejercicio interválico de alta intensidad en mejorar el VO2 pico en pacientes tras SCA

Introduction and objectivesWe compared the effects of 12 weeks of low-volume high-intensity interval training (LV-HIIT) vs moderate-intensity continuous exercise training (MICET) on cardiopulmonary exercise test parameters and the proportion of non/low responders (NLR) to exercise training in post-acute coronary syndrome (ACS) patients. MethodsPatients with a recent ACS were randomized to LV-HIIT, MICET, or a usual care group. LV-HIIT consisted of 2 to 3 sets of 6 to 10minutes with repeated bouts of 15 to 30seconds at 100% of peak workload alternating with 15 to 30seconds of passive recovery. Cardiopulmonary exercise test parameters were assessed, and key exercise variables were calculated. Training response was assessed according to the median VO2peak change post vs pretraining in the whole cohort (stratification NLR vs high response). ResultsFifty patients were included in the analysis (LV-HIIT, n=23; MICET, n=18; usual care, n=9) and 74% were male. The proportion of NLR was higher in the LV-HIIT group than in the MICET group (LV-HIIT 61%, MICET 21%, and usual care 80%; P=.0040). VO2peak-dependent variables (VO2peak, percent-predicted VO2peak) improved in both training groups (P=.002 and P <.0001 for time with LV-HIIT and MICET, respectively), but the improvement was more pronounced with MICET (P=.004 and P=.001 for interaction, respectively). The ΔVO2/Δworkload slope improved only with MICET (P=.021). ConclusionsIn patients with a recent ACS, several prognostic VO2peak-dependent variables were improved after LV-HIIT, but the improvement was more pronounced or only found after MICET. Low-volume HIIT resulted in a higher proportion of NLR than isocaloric MICET.Clinical trialsregistered at ClinicalTrials.gov (Identifiers: NCT03414996 and NCT02048696)

Carotid Artery Longitudinal Wall Motion Is Unaffected by 12 Weeks of Endurance, Sprint Interval or Resistance Exercise Training

Carotid artery longitudinal wall motion (CALM) exhibits reduced magnitude in older adults and in individuals with chronic diseases, although longitudinal data are lacking to indicate how changes in CALM might develop over time. Therefore, the aim of this study was to investigate the effect of exercise training in healthy men on CALM using a retrospective design. Carotid ultrasound data were analysed from two previous studies in which men performed 12 wk of moderate-intensity continuous exercise training (n = 9), sprint-interval training (n = 7), higher-repetition resistance exercise training (n = 15) or lower-repetition resistance exercise training (n = 15). The CALM pattern was unaltered after 12 wk of exercise training, regardless of exercise mode, with no differences in systolic or diastolic CALM magnitudes (p > 0.05), similar to carotid intima-media thickness (p > 0.05). Our findings suggest that CALM is resistant to transient changes in lifestyle factors, similar to wall thickness in otherwise healthy populations.

High-Intensity Interval Versus Moderate-Intensity Continuous Training in Individuals With Parkinson's Disease: Hemodynamic and Functional Adaptation.

To investigate the effect of high-intensity interval training (HIIT) versus moderate-intensity continuous exercise training (MICE) on hemodynamic and functional variables in individuals with Parkinson's disease. Twenty participants (13 men) were randomly assigned to a thrice-weekly HIIT (n = 12) or MICE (n = 8) for 12 weeks. Hemodynamic (resting heart rate and blood pressure, carotid femoral pulse wave velocity, endothelial reactivity, and heart rate variability) and functional variables (5-time sit-to-stand, timed up and go, and 6-min walking tests) assessed before and after training. Demographic, hemodynamic and functional variables were similar between groups at baseline. Endothelial reactivity tended to increase after HIIT, but not after MICE, resulting in improved level (∼8%, P < .01) of this variable in HIIT versus MICE during follow-up. Six-minute walking test improved after HIIT (10.4 ± 3.8%, P < .05), but did not change after MICE. Sit to stand improved similarly after HIIT (27.2 ± 6.1%, P < .05) and MICE (21.5 ± 5.4%, P < .05). No significant changes were found after HIIT or MICE in any other variable assessed. These results suggest that exercise intensity may influence training-induced adaptation on endothelial reactivity and aerobic capacity in individuals with Parkinson's disease.

Interaction of genetic background and exercise training intensity on endothelial function in mouse aorta.

The purpose of this study was to characterize the genetic contribution to endothelial adaptation to exercise training. Vasoreactivity was assessed in aortas from four inbred mouse strains (129S1, B6, NON, and SJL) after 4 weeks of moderate intensity continuous exercise training (MOD), high intensity interval training (HIT) or in sedentary controls (SED). Intrinsic variations in endothelium-dependent vasorelaxation (EDR) to acetylcholine (ACh) as well as vasocontractile responses were observed across SED groups. For responses to exercise training, there was a significant interaction between mouse strain and training intensity on EDR. Exercise training had no effect on EDR in aortas from 129S1 and B6 mice. In NON, EDR was improved in aortas from MOD and HIT compared with respective SED, accompanied by diminished responses to PE in those groups. Interestingly, EDR was impaired in aorta from SJL HIT compared with SED. The transcriptional activation of endothelial genes was also influenced by the interaction between mouse strain and training intensity. The number of genes altered by HIT was greater than MOD, and there was little overlap between genes altered by HIT and MOD. HIT was associated with gene pathways for inflammatory responses. NON MOD genes showed enrichment for vessel growth pathways. These findings indicate that exercise training has non-uniform effects on endothelial function and transcriptional activation of endothelial genes depending on the interaction between genetic background and training intensity.

Moderate-intensity continuous exercise is superior to high-intensity interval training in the proportion of VO2peak responders after ACS.

We compared the effects of 12 weeks of low-volume high-intensity interval training (LV-HIIT) vs moderate-intensity continuous exercise training (MICET) on cardiopulmonary exercise test parameters and the proportion of non/low responders (NLR) to exercise training in post-acute coronary syndrome (ACS) patients. Patients with a recent ACS were randomized to LV-HIIT, MICET, or a usual care group. LV-HIIT consisted of 2 to 3 sets of 6 to 10minutes with repeated bouts of 15 to 30seconds at 100% of peak workload alternating with 15 to 30seconds of passive recovery. Cardiopulmonary exercise test parameters were assessed, and key exercise variables were calculated. Training response was assessed according to the median VO2peak change post vs pretraining in the whole cohort (stratification NLR vs high response). Fifty patients were included in the analysis (LV-HIIT, n=23; MICET, n=18; usual care, n=9) and 74% were male. The proportion of NLR was higher in the LV-HIIT group than in the MICET group (LV-HIIT 61%, MICET 21%, and usual care 80%; P=.0040). VO2peak-dependent variables (VO2peak, percent-predicted VO2peak) improved in both training groups (P=.002 and P <.0001 for time with LV-HIIT and MICET, respectively), but the improvement was more pronounced with MICET (P=.004 and P=.001 for interaction, respectively). The ΔVO2/Δworkload slope improved only with MICET (P=.021). In patients with a recent ACS, several prognostic VO2peak-dependent variables were improved after LV-HIIT, but the improvement was more pronounced or only found after MICET. Low-volume HIIT resulted in a higher proportion of NLR than isocaloric MICET. Clinical trialsregistered at ClinicalTrials.gov (Identifiers: NCT03414996 and NCT02048696).

P638High intensity interval exercise training improves endothelial function in patients with heart failure with preserved ejection fraction

Abstract Background Cardiac rehabilitation has traditionally invoved low-to moderate intensity continuous exercise training (MICT). There is growing evidence that high intensity interval exercise training (HIIT) shows similar or greater efficacy compared with MICT. However, the relationship between the training modality and its effects on endothelial function still remains to be elucidated. Purpose To evaluate the impact of high intensity interval exercise training versus low-to moderate intensity continuous exercise training on circulating blood markers of endothelial function: the stable end product of nitric oxide (NOx), S–nitrosothiols (RSNO–reservoir for bioavailable nitric oxide), dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) in patients (pts) with heart failure with preserved ejection fraction (HFpEF). Methods A total of 43 pts with HFpEF (mean age 57.5±6.8y) admitted at residential rehabilitation center were enrolled in the study. Patients were randomized to HIIT, (HIIT group, n=20) and MICT, (MICTgroup, n=23). At baseline and 3 weeks later, in all pts values of NOx, RSNO, ADMA and SDMA were determined and exercise test was performed. Results After 3 weeks NOx increased significantly in both groups: in HIITgroup (from 34.7±7.5 to 48.5±8.3 μmol/l, P&lt;0.0001), in MICTgroup (from 35.0±9.5 to 42.5±10.0 μmol/l, P&lt;0.05), and value of NOx after 3 weeks was higher in HIIT than in MICT group (P&lt;0.05). Value of ADMA as well of SDMA decreased in both groups after 3 weeks, and this decrease was significant in HIIT group: ADMA in HIIT group (from 0.305±0.055 to 0.250±0.077 μmol/l, P&lt;0.005) and in MICT group (from 0.325±0.069 to 0.280±0.140 μmol/l, ns); SDMA in HIIT group (from 0.285±0.050 to 0.240±0.060 μmol/l, P&lt;0,005) and in MICT group (from 0.270±0.080 to 0.247±0.063 μmol/l, ns). Value of RSNO significantly increased in both groups, with higher increase in HIIT group: in HIIT group (from 3.0±1.5 to 5.1±1.7 μmol/l, P&lt;0.001), in MICTgroup (from 3.2±1.7 to 4.5±2.3 μmol/l, P&lt;0.05). Compared to the baseline, at the end of the study, exercise capacity (METs) was significantly higher in both groups (P&lt;0.0001). Higher increase in METs in HIIT group during exercise training (by 39.8%), compared to increase in MICT group (by 27.2%), resulted in significantly higher exercise tolerance in HIIT than in MICT group at the end of the study (P&lt;0.02). In both groups, adverse events during or after exercise training, were not occurred. Conclusions In pts with HFpEF high intensity interval exercise training as well as low-to moderate intensity continuous exercise training induced favorable modification of endothelial function, expressed through increase of NOx and RSNO, and decrease of ADMA and SDMA. More significant increase of NOx and RSNO, and significant decrease of ADMA and SDMA gives an advantage to HIIT over MICT exercise training in patients with HFpEF.

P1534Short time and short term of high-intensity intermittent exercise training reduces arterial stiffness via upregulation of endothelial nitric oxide signalling

Abstract Introduction Conventionally, as an exercise mode which leads to reduction of arterial stiffness, it is well used that moderate-intensity continuous exercise training (MICT). High-intensity interval training (HIIT), such as HIIT program with a total exercise time of 15–30 min is highly time-effective as an exercise mode for which reduces risks of cardiovascular disease. Recent study showed that even shorter HIIT leads to an effective reduction in arterial stiffness. Therefore, HIIT is an effectively exercise therapy which can use in patients with cardiovascular diseases. Although MICT induces vasodilation by acceleration of nitric oxide (NO) production via upregulating arterial endothelial NO synthase (eNOS)/protein kinase B (Akt) signalling pathway, an underlying mechanism of HIIT effects remains unclear. Purpose This study aimed to clarify the effects of short HIIT on arterial stiffness and arterial NO production in rats. Methods Forty 10-week-old male Sprague-Dawley rats were randomly divided into four groups; CON: 8-week sedentary control, MICT: treadmill running for 60 min at 30m/min, 5 days/wk for 8weeks, HIIT: fourteen 20 sec swimming sessions with a weight equivalent to 14–16% of each body weight and 10 sec pause was allowed between exercise sessions, 4 days/wk for 6 weeks from 12-week-old, and RT: ladder climbing, 8–10sets/day, 3 days/wk for 8 weeks groups (n=10 each group). After training session, we measured aortic pulse wave velocity (aortic PWV) as an index of arterial stiffness and plasma nitrite/nitrate (NOx) concentrations and phosphorylation of eNOS and Akt in the aorta. Results Aortic PWV was significantly reduced in both MICT and HIIT groups as compared to CON and RT groups (P&lt;0.05), whereas there was no difference between RT and CON groups. Additionally, arterial phosphorylations of eNOS and Akt and plasma NOx levels were significantly elevated in both MICT and HIIT groups as compared to CON and RT groups (P&lt;0.05), whereas there was no difference between RT and CON groups. Moreover, HIIT-induced reduction of aortic PWV and increase in eNOS and Akt phosphorylations and plasma NOx levels were equal to these MICT effects. Arterial eNOS phosphorylation was negatively correlated with aortic PWV in all groups (r=−0.38, P&lt;0.05). Further study was conducted whether a single-bout high-intensity intermittent exercise accelerates NO production. After acute high-intensity intermittent exercise, plasma NOx levels were significantly elevated (P&lt;0.05). Conclusion These results suggest that HIIT increases NO production via the upregulation of arterial Akt/eNOS signalling pathway, resulting in the reduction of arterial stiffness, despite a reduction in total exercise volume as compared with MICT. Acknowledgement/Funding JSPS KAKENHI (#17H02182 and #16K13059 for M. Iemitsu; #18H06423 for N. Hasegawa)

Personalized Moderate-Intensity Exercise Training Combined with High-Intensity Interval Training Enhances Training Responsiveness.

This study sought to determine if personalized moderate-intensity continuous exercise training (MICT) combined with high-intensity interval training (HIIT) was more effective at improving comprehensive training responsiveness than MICT alone. Apparently healthy, but physically inactive men and women (n = 54) were randomized to a non-exercise control group or one of two 13-week exercise training groups: (1) a personalized MICT + HIIT aerobic and resistance training program based on the American Council on Exercise guidelines, or (2) a standardized MICT aerobic and resistance training program designed according to current American College of Sports Medicine guidelines. Mean changes in maximal oxygen uptake (VO2max) and Metabolic (MetS) z-score in the personalized MICT + HIIT group were more favorable (p < 0.05) when compared to both the standardized MICT and control groups. Additionally, on the individual level, there were positive improvements in VO2max (Δ > 4.9%) and MetS z-score (Δ ≤ −0.48) in 100% (16/16) of participants in the personalized MICT + HIIT group. In the present study, a personalized exercise prescription combining MICT + HIIT in conjunction with resistance training elicited greater improvements in VO2max, MetS z-score reductions, and diminished inter-individual variation in VO2max and cardiometabolic training responses when compared to standardized MICT.

Passive Heat Therapy in Sedentary Humans Improves Aerobic Capacity and Insulin Sensitivity via Increases in Skeletal Muscle Capillarisation and eNOS

OBJECTIVESNegative associations have been reported in a sedentary Finnish population between sauna bathing and all‐cause mortality1, while a joint association of sauna bathing and cardiorespiratory fitness was seen on cardiovascular and all‐cause mortality in a more recent study2. These associations give scientific support to the ‘proverbial wisdom’ in Scandinavia that frequent sauna bathing has multiple health and fitness benefits. The first objective of the current study was to investigate the hypotheses that 1) passive heat therapy (PHT, as occurs in sauna bathing) similar to moderate intensity continuous exercise training (MICT) increases whole body insulin sensitivity and VO2max and that 2) this is the result of increases both in a) skeletal muscle capillarisation and endothelial specific eNOS content and b) mitochondrial, GLUT4 and IMTG content.METHODSTwenty young sedentary males (21 ± 1 years; Body Mass Index (BMI) 25 ± 1 kg/m2) were allocated to either 6 weeks of PHT (n=10; 40–50 min at 40°C in a heat chamber, 3 x per week) or MICT (n=10; time matched cycling at ~65% VO2peak). VO2peak and whole‐body insulin sensitivity were measured and muscle biopsies were taken from the vastus lateralis muscle pre and post the interventions. Immunofluorescence microscopy was used to assess changes in capillarisation measures and endothelial specific eNOS content, as described before 3 and skeletal muscle mitochondrial density, GLUT4 content and IMTG content as described elsewhere4.RESULTSPHT and MICT increased VO2peak (PHT 5%, MICT 7%; P&lt;0.05) and insulin sensitivity index (ISI, Matsuda) (PHT 15%, MICT 36%; P&lt;0.05). PHT and MICT both increased capillary density, capillary–fibre perimeter exchange index, and endothelial specific eNOS content (Table 1). However, unlike MICT (P&lt;0.05) PHT did not increase mitochondrial density (P=0.443), total GLUT4 content (P=0.217) and IMTG content (P=0.957).CONCLUSIONThis study is the first to show that 6 weeks PHT induces similar increases in aerobic capacity and whole‐body insulin sensitivity as a time matched traditional MICT intervention. The study also shows and that these improvements coincide with increases in skeletal muscle capillarisation and endothelial specific eNOS content similar in magnitude to MICT. As skeletal muscle mitochondrial density, GLUT4 content and IMTG concentration were not changed by PHT the data suggest that the microvascular adaptations alone are responsible for the observed effects. This leads to the conclusion that PHT (and sauna bathing) may be effective alternative interventions to achieve significant health benefits in the large and growing population of sedentary and elderly people unable to exercise or to chronically adhere to high physical activity levels.Support or Funding InformationNAThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Changes in fat oxidation in response to various regimes of high intensity interval training (HIIT).

Increased whole-body fat oxidation (FOx) has been consistently demonstrated in response to moderate intensity continuous exercise training. Completion of high intensity interval training (HIIT) and its more intense form, sprint interval training (SIT), has also been reported to increase FOx in different populations. An explanation for this increase in FOx is primarily peripheral adaptations via improvements in mitochondrial content and function. However, studies examining changes in FOx are less common in response to HIIT or SIT than those determining increases in maximal oxygen uptake which is concerning, considering that FOx has been identified as a predictor of weight gain and glycemic control. In this review, we explored physiological and methodological issues underpinning existing literature concerning changes in FOx in response to HIIT and SIT. Our results show that completion of interval training increases FOx in approximately 50% of studies, with the frequency of increased FOx higher in response to studies using HIIT compared to SIT. Significant increases in β-HAD, citrate synthase, fatty acid binding protein, or FAT/CD36 are likely responsible for the greater FOx seen in these studies. We encourage scientists to adopt strict methodological procedures to attenuate day-to-day variability in FOx, which is dramatic, and develop standardized procedures for assessing FOx, which may improve detection of changes in FOx in response to HIIT.

The Impact of Burst Exercise on Cardiometabolic Status of Patients Newly Diagnosed With Type 2 Diabetes

BackgroundThe impact of burst high-intensity exercise on physiological, cardiometabolic, and biochemical variables compared with traditional moderate-intensity continuous exercise training (MICT) has yet to be assessed in patients with type 2 diabetes (T2D). We compared the impact of multiple short-duration, high-intensity burst exercise sessions to MICT on cardiometabolic variables in patients with T2D. MethodsForty newly diagnosed patients with T2D not receiving lipid lowering or hypoglycemic medications were randomized to 40 minutes of MICT (60% of maximal heart rate) 5 days per week or 3 continuous bursts of 12 minutes of high-intensity exercise (85% of maximal heart rate) 5 days per week for 3 months. Body mass index, hemoglobin A1C (HbA1C), and lipid profile were assessed before and after 3 months of exercise training. ResultsBurst exercise resulted in greater body mass index reduction than did MICT (–2.1 ± 1.2 kg/m2 vs –0.7 ± 0.7 kg/m2, respectively; P < 0.05). There was a greater reduction at 3 months (P < 0.05) in HbA1C levels in the burst exercise group (8.14% ± 0.49% to 7.32% ± 0.39%) compared with the MICT group (8.18% ± 0.35% to 7.94% ± 0.41%). Compared with MICT, burst exercise was associated with a greater reduction in low-density lipoprotein cholesterol (–11 vs –4%; P < 0.05) and a greater increase in high-density lipoprotein cholesterol (22% vs 3%; all P < 0.05). After 3 months, patients in the burst exercise group attained greater exercise time on the treadmill (exercise capacity) than did those prescribed MICT (6.87 ± 1.44 minutes vs 5.40 ± 1.96 minutes; P < 0.001). ConclusionsFindings from the current study support better cardiometabolic benefits of burst exercise compared with MICT over 3 months in patients with newly diagnosed T2D.

Energy-matched moderate and high intensity exercise training improves nonalcoholic fatty liver disease risk independent of changes in body mass or abdominal adiposity — A randomized trial

Background and PurposeExercise training is commonly prescribed for individuals diagnosed with nonalcoholic fatty liver disease (NAFLD); however, consensus regarding the volume and intensity of exercise for optimal benefits is lacking. Thus, we determined whether high intensity interval exercise training (HIIT) produced greater reductions in intrahepatic lipid (IHL) content and NAFLD risk factors compared with energy-matched moderate intensity continuous exercise training (MICT) in obese adults with liver steatosis. MethodsEighteen obese adults were randomized to either 4weeks of HIIT (4min 80% VO2peak/3min, 50% VO2peak) or MICT (55% VO2peak, ~60min), matched for energy expenditure (~400kcal/session) and compared to five non-exercising age-matched control subjects. IHL was measured by 1H-MRS and frequent blood samples were analyzed for glucose, insulin, c-peptide, and NEFA levels during a liquid meal test (180min) to characterize metabolic phenotype. ResultsBaseline body weight, visceral abdominal adiposity, and fasting insulin concentrations were greater in the MICT vs HIIT group (P<0.05), while IHL was tightly matched between MICT and HIIT subjects (P>0.05), albeit higher than control subjects (P<0.01). Visceral abdominal adiposity, body mass, liver aminotransferases (ALT, AST), and hepatic apoptotic/inflammatory markers (cytokeratin 18 and fetuin a) were not reduced with either exercise training intervention (P>0.05). Both HIIT and MICT lowered IHL (HIIT, −37.0±12.4%; MICT, −20.1±6.6%, P<0.05); however, the reduction in IHL was not statistically different between exercise intensities (P=0.25). Furthermore, exercise training decreased postprandial insulin, c-peptide, and lipid peroxidation levels (iAUC, P<0.05). ConclusionsCollectively, these findings indicate that energy-matched high intensity and moderate intensity exercise are effective at decreasing IHL and NAFLD risk that is not contingent upon reductions in abdominal adiposity or body mass.

Lipid droplet remodelling and reduced muscle ceramides following sprint interval and moderate-intensity continuous exercise training in obese males.

In obesity, improved muscle insulin sensitivity following exercise training has been linked to the lowering of diacylglycerol (DAG) and ceramide concentrations. Little is known, however, about how improved insulin action with exercise training in obese individuals relates to lipid droplet (LD) adaptations in skeletal muscle. In this study we investigated the hypothesis that short-term sprint interval training (SIT) and moderate-intensity continuous training (MICT) in obese individuals would increase perilipin (PLIN) expression, increase the proportion of LDs in contact with mitochondria and reduce muscle concentrations of DAGs and ceramides. Sixteen sedentary obese males performed 4 weeks of either SIT (4-7 × 30 s sprints at 200% Wmax, 3 days week) or MICT (40-60 min cycling at ~65% VO2peak, 5 days per week), and muscle biopsies were obtained pre- and post-training. Training increased PLIN2 (SIT 90%, MICT 68%) and PLIN5 (SIT 47%, MICT 34%) expression in type I fibres only, and increased PLIN3 expression in both type I (SIT 63%, MICT 67%) and type II fibres (SIT 70%, MICT 160%) (all P<0.05). Training did not change LD content but increased the proportion of LD in contact with mitochondria (SIT 12%, MICT 21%, P<0.01). Ceramides were reduced following training (SIT -10%, MICT -7%, P<0.05), but DAG was unchanged. No training × group interactions were observed for any variables. These results confirm the hypothesis that SIT and MICT results in remodelling of LDs and lowers ceramide concentrations in skeletal muscle of sedentary obese males.

Interval and continuous aerobic exercise training similarly increase cardiac function and autonomic modulation in infarcted mice.

The present study aimed to compare the effects of moderate-intensity continuous and high-intensity interval exercise training (ET) on exercise tolerance, cardiac morphometry and function, hemodynamic, and cardiac autonomic modulation in myocardial infarcted mice. Wild-type mice (WT) were divided into four groups: sedentary WT (S); WT myocardium infarction sedentary (IS); WT myocardium infarction underwent to moderate-intensity continuous ET (MICT), and WT myocardium infarction underwent to high-intensity interval ET (MIIT). After 60 days of descending coronary artery ligation, moderate-intensity continuous ET consisted of running at 60% of maximum, while the high-intensity interval training consisted of eight sprints of 4 min at 80% of maximum and a 4-min recovery at 40% of maximum. Both exercises were performed 1 hr a day, 5 days a week, during 8 weeks. Results demonstrated that IS showed elevated exercise tolerance, as well as decreased hemodynamic and heart function, and autonomic control. On the other hand, both programs of ET were equally effective to increase all parameters, without further differences between the groups. In conclusion, the results of the present study showed that myocardial infarction leads to damage in both investigated strains and the two types of physical exercise attenuated the major impairments provoked by myocardial infarction in exercise tolerance, cardiac structure, cardiac function, hemodynamic and cardiac autonomic modulation.

Within-Session Responses to High Intensity Interval Training in Spinal Cord Injury

High intensity interval training (HIIT) has shown to be a robust alternative to traditional aerobic training (Gillen et al. 2014, 2016; Astorino et al. 2011). In most individuals, incorporation of HIIT elicits increases in maximum oxygen uptake and overall health status, yet its feasibility in persons with spinal cord injury (SCI) is unknown. PURPOSE: The aim of this study was to compare acute changes in cardiorespiratory and metabolic variables during different HIIT regimens versus moderate intensity continuous exercise training (MICT). METHODS: Nine habitually active men and women (injury duration = 6.8 ± 6.2 yr) with SCI initially underwent determination of peak oxygen uptake (VO2peak) on an arm ergometer. During subsequent sessions, they completed MICT, HIIT, or sprint interval training (SIT). MICT consisted of 25 min of arm cycling at 45 %Wpeak. HIIT consisted of eight 60 s bouts at 70 %Wpeak separated by 90 s of active recovery at 10 %Wpeak, while SIT required eight 30 s bouts at 105 %Wpeak separated by 120 s of active recovery at 10 %Wpeak. Gas exchange data, heart rate (HR), and blood lactate concentration were measured. Each session was broken up into 16 phases (eight exercise and eight recovery data points for HIIT/SIT) for which mean oxygen uptake and HR were determined. RESULTS: Peak VO2 was higher (p = 0.03) in response to HIIT (1.13 ± 0.44 L/min at bout 8) and SIT (1.02 ± 0.37 L/min at bout 8) compared to MICT (0.90 ± 0.29 L/min), but mean VO2 was similar (p > 0.05) between MICT (0.86 ± 0.17 L/min), HIIT (0.89 ± 0.20 L/min), and SIT (0.82 ± 0.19 L/min). Peak HR was higher (p < 0.05) with HIIT (90 %VO2peak and 99 % HRpeak) and SIT (80 %VO2peak and 96 %HRpeak) versus MICT. There was no difference in mean HR across bouts (p = 0.16) which was equal to 130.7 ± 19.3, 129.3 ± 18.6, and 126.9 ± 14.9 b/min for HIIT, SIT, and MICT, equivalent to 79 - 82 %HRpeak. CONCLUSION: Despite a higher intensity, all participants preferred HIIT or SIT versus MICT. Compared to MICT, submaximal or supramaximal interval training elicits higher peak oxygen uptake and heart rate. The long-term efficacy and feasibility of HIIT in this population should be explored, considering that exercise intensity seems to be the most important variable manipulated in exercise programming to optimize maximal oxygen uptake. This study was partially funded by a University GPSM grant.

Effects of High-Intensity Intermittent Exercise Training on Appetite Regulation.

An acute bout of high-intensity intermittent exercise suppresses ad libitum energy intake at the postexercise meal. The present study examined the effects of 12 wk of high-intensity intermittent exercise training (HIIT) compared with moderate-intensity continuous exercise training (MICT) on appetite regulation. Thirty overweight inactive men (body mass index, 27.2 ± 1.3 kg·m(-2); V˙O2peak, 35.3 ± 5.3 mL·kg(-1)·min(-1) were randomized to either HIIT or MICT (involving 12 wk of training, three sessions per week) or a control group (CON) (n = 10 per group). Ad libitum energy intake from a laboratory test meal was assessed after both a low-energy (847 kJ) and a high-energy preload (2438 kJ) before and after the intervention. Perceived appetite and appetite-related blood variables were also measured. There was no significant effect of the intervention period on energy intake at the test meal after the two different preloads (P ≥ 0.05). However, the 95% confidence interval indicated a clinically meaningful decrease in energy intake after the high-energy preload compared with the low-energy preload in response to HIIT (516 ± 395 kJ decrease), but not for MICT or CON, suggesting improved appetite regulation. This was not associated with alterations in the perception of appetite or the circulating concentration of a number of appetite-related peptides or metabolites, although insulin sensitivity was enhanced with HIIT only (P = 0.003). HIIT seems to benefit appetite regulation in overweight men. The mechanisms for this remain to be elucidated.