High-intensity Interval Group Research Articles

INCREASED HIPPOCAMPAL ATROPHY IN HIGH INTENSITY INTERVAL TRAINING GROUP 4 YEARS AFTER 5-YEAR EXERCISE INTERVENTION

Abstract The Generation 100 Study is a randomized controlled trial (NCT01666340) investigating the effects of a 5-year exercise intervention on several health outcomes, including brain volumes from MRI. Participants (born 1936-42) were living independently at inclusion. They were randomized (1-1-2) to supervised exercising with either high intensity interval (HIIT) or moderate continuous training (MICT) twice a week, or to a control group adhering to the national guidelines of ≥30 min of moderate to vigorous physical activity at least 5 days a week. The intervention lasted for 5 years, during which participants underwent physical and clinical examinations at baseline, 1-, 3-, 5-years. 105 participants (n: HIIT=33, MICT=24, Cont=48) also underwent brain MRI at 3T. Linear mixed models were used and the interaction between group and time on brain volumes was the main outcome. We have previously reported that the HIIT group had significantly greater hippocampal atrophy rate compared to the control group during the intervention. Participants were invited back 4 years after end of intervention and underwent the same examinations including brain MRI . A total 73 participants (n: HIIT24=, MICT=19, Cont=30) took part. The HIIT group trained at a higher intensity than the other groups. There were no associations between objective VO2 or any self-reported exercise measurements and hippocampal volume/atrophy rate at any timepoint. Still, the hippocampal atrophy rate remained greater in the HIIT group than in the controls 4 years after end of the exercise intervention.

Effect of High-Intensity Interval, Moderate-Intensity Continuous, and Self-Selected Intensity Training on Health and Affective Responses

ABSTRACT Purpose: To compare the effects of 12-week high-intensity interval (HIIT), moderate-intensity continuous (MICT), and self-selected intensity training (SSIT) on health outcomes and affective responses. Methods: Seventy-three overweight/obese inactive adults (62% woman; age, 31.4 ± 7.2 years; height, 1.66 ± 0.09 cm; Body mass index, 28.9 ± 2.7 kg.m−2) who were randomized into HIIT (n = 23), MICT (n = 24) and SSIT (n = 26) groups. The training was conducted three times per week in an outdoor environment, with 4 weeks under direct supervision and 8 weeks with semi-supervision. Cardiorespiratory fitness, body composition, and metabolic profile were evaluated at baseline and at the end of the 4th and 12th weeks. Core affect was measured during all training sessions. Results: Peak oxygen uptake improved in all groups after 4 and 12 weeks compared with baseline. Only the SSIT had reductions in body fat throughout the intervention. No improvements were observed in the metabolic profile across all groups. SSIT was perceived as more pleasurable than HIIT; however, there were no differences in affective responses between SSIT and MICT. Affective responses in-task (e.g. negative and positive peak, rate of change and affect at the end of the exercise session) predicted the HIIT and SSIT exercises attendance rate. Conclusion: Regardless of the exercise training protocol, overweight/obese inactive adults improved health outcomes, which suggests the prescribing HIIT, MICT, and SSIT in outdoor environments. SSIT should be considered in order to optimize the pleasure during training sessions. Affective response more positive in-task of the HIIT and SSIT is associated with greater attendance rate in these exercise protocols.

Time-Course of Redox Status, Redox-Related, and Mitochondrial-Dynamics-Related Gene Expression after an Acute Bout of Different Physical Exercise Protocols.

We investigated the magnitude of exercise-induced changes in muscular bioenergetics, redox balance, mitochondrial function, and gene expression within 24 h after the exercise bouts performed with different intensities, durations, and execution modes (continuous or with intervals). Sixty-five male Swiss mice were divided into four groups: one control (n = 5) and three experimental groups (20 animals/group), submitted to a forced swimming bout with an additional load (% of animal weight): low-intensity continuous (LIC), high-intensity continuous (HIC), and high-intensity interval (HII). Five animals from each group were euthanized at 0 h, 6 h, 12 h, and 24 h postexercise. Gastrocnemius muscle was removed to analyze the expression of genes involved in mitochondrial biogenesis (Ppargc1a), fusion (Mfn2), fission (Dnm1L), and mitophagy (Park2), as well as inflammation (Nos2) and antioxidant defense (Nfe2l2, GPx1). Lipid peroxidation (TBARS), total peroxidase, glutathione peroxidase (GPx), and citrate synthase (CS) activity were also measured. Lactacidemia was measured from a blood sample obtained immediately postexercise. Lactacidemia was higher the higher the exercise intensity (LIC < HIC < HII), while the inverse was observed for TBARS levels. The CS activity was higher in the HII group than the other groups. The antioxidant activity was higher 24 h postexercise in all groups compared to the control and greater in the HII group than the LIC and HIC groups. The gene expression profile exhibited a particular profile for each exercise protocol, but with some similarities between the LIC and HII groups. Taken together, these results suggest that the intervals applied to high-intensity exercise seem to minimize the signs of oxidative damage and drive the mitochondrial dynamics to maintain the mitochondrial network, similar to low-intensity continuous exercise.

High Intensity Interval Training Leads to Similar Inflammatory Activation as Seen With Traditional Training in Chronic Heart Failure.

BackgroundInflammatory activation has been associated with the severity and progression of chronic heart failure (CHF). Although cardiac rehabilitation is an important therapy, acute bouts of exercise may lead to increases in pro-inflammatory cytokines with exercise intensity mediating these changes.ObjectiveTo evaluate the acute inflammatory response in patients living with CHF during a randomized trial following Steady State (SS) or High Intensity Interval (HIIT) training.MethodsPatients living with CHF (n = 14) were stratified (for body mass and aerobic power) and randomized into SS and HIIT cycle exercise. The HIIT exercise training involved 2 min work:recovery phases at 90:40% heart rate reserve. The SS exercise training involved continuous exercise at 65% of heart rate reserve (matched total work). Acute inflammatory markers were evaluated (via ELISA) at baseline, immediately following the bout, and at 6, 24, and 48 h post-exercise.ResultsThere was limited differences in the changes in inflammatory biomarkers across time between the HIIT and SS groups. Both groups experienced a significant (p < 0.05) change in Interleukin-6 immediately post-exercise.ConclusionsA single bout of HIIT or SS does not result in excessive inflammatory activation in CHF patients. Acute HIIT and SS result in similar changes in inflammatory markers. These findings have important implications for exercise training and rehabilitation programs in persons living with CHF.

High-Intensity Interval Training Improves Physical Function, Prevents Muscle Loss, and Modulates Macrophage-Mediated Inflammation in Skeletal Muscle of Cerebral Ischemic Mice.

Although skeletal muscle is the main effector organ largely accounting for disability after stroke, considerably less attention is paid to the secondary abnormalities of stroke-related skeletal muscle loss. It is necessary to explore the mechanism of muscle atrophy after stroke and further develop effective rehabilitation strategy. Here, we evaluated the effects of high-intensity interval (HIIT) versus moderate-intensity aerobic training (MOD) on physical function, muscle mass, and stroke-related gene expression profile of skeletal muscle. After the model of middle cerebral artery occlusion (MCAO) was successfully made, the blood lactate threshold corresponding speed (SLT) and maximum speed (Smax) were measured. Different intensity training protocols (MOD < SLT; SLT < HIIT < Smax) were carried out for 3 weeks beginning at 7 days after MCAO in the MOD and HIIT groups, respectively. We found that both HIIT and MOD prevented stroke-related gastrocnemius muscle mass loss in MCAO mice. HIIT was more beneficial than MOD for improvements in muscle strength, motor coordination, walking competency, and cardiorespiratory fitness. Furthermore, HIIT was superior to MOD in terms of reducing lipid accumulation, levels of IL-1β and IL-6 in paretic gastrocnemius, and improving peripheral blood CD4+/CD8+ T cell ratio, level of IL-10. Additionally, RNA-seq analysis revealed that the differentially expressed genes among HIIT, MOD, and MCAO groups were highly associated with signaling pathways involved in inflammatory response, more specifically the I-kappaB kinase/NF-kappaB signaling. Following the outcome, we further investigated the infiltrating immune cells abundant in paretic muscles. The results showed that HIIT modulated macrophage activation by downregulating CD86+ (M1 type) macrophages and upregulating CD163+ (M2 type) macrophages via inhibiting the TLR4/MyD88/NFκB signaling pathway and exerting an anti-inflammatory effect in paretic skeletal muscle. It is expected that these data will provide novel insights into the mechanisms and potential targets underlying muscle wasting in stroke.

The role of different exercises in irisin, heat shock protein 70 and some biochemical parameters.

BackgroundThe aim of the study was to determine the effects of different and regularly applied exercise programs on irisin, heat shock protein 70 and some biochemical parameters.Methods120 male university students participated in the study. Participants were divided into 4 equal groups as control (C), resistance exercise group (RE), high intensity interval (HIIT) and aerobic exercise group (AE). While the control group did not perform any exercise, the pre-determined exercise programs were applied to the other groups for 8 weeks and 3 days in a week. Blood samples were taken from all participants before and after the exercise program. Cholesterol, High-density Lipoprotein (HDL) and Low-density Lipoprotein (LDL) cholesterol, triglyceride (TG), Creatine kinase (CK), Lactate dehydrogenase (LDH), Irisin and Heat shock protein 70 (HSP70) levels were analyzed in blood samples.ResultsIt is determined that there are significant differences in pre-posttest values of the AE group's LDH, cholesterol, HDL-cholesterol, TG and HSP 70 levels, HIIT group's CK, LDH, Cholesterol, HDL-cholesterol, TG, Irisin and HSP70 levels and RE group's CK, LDH, Cholesterol, LDL-cholesterol, TG and Irisin levels (p<0.05).ConclusionsIt can be said that exercise can provide improvements in lipid profile, changes in HSP70 levels may vary depending on muscle damage, the increase of irisin due to exercise.

The effect of Progressive Resistance Training and High Intensity Interval Training on TRAF6 gene expression of the heart muscle and serum TNF-α levels in male diabetic rats

Background: The most common causes of mortality in diabetic patients are cardiovascular disorders, one of the reasons being inflammatory factors. Given that physical activity can reduce inflammation, the present study was to investigate the effects of two types of Progressive Resistance Training (RT) and High Intensity Interval (HIIT) on the expression of TRAF6 gene and serum levels of TNF-α in male diabetic rats. Methods: In this experimental study, 72 male rats were divided into 6 groups of 12 diabetic rats (n=12), control (n=12), diabetic High Intensity Interval Training (n=12), High Intensity Interval Training(n=12), diabetic Progressive Resistance Training(n=12) and Progressive Resistance Training(n=12). Progressive Resistance Training was performed in a 6-weekly 3-session, climbing the vertical ladder, with 50%, 75%, 90% and 100% the body weight of the animals. After successful completion, 30 gr were added to the weights, to the extent that the rats cannot carry the ladder. High Intensity Interval Training were also performed at 6-weekly 3-session, with an intensity of 50 to 110% of the VO2max. 24 hours after the completion of the training, the functional test was taken and the animals were autopsy 48 hours after the test. Finally, the expression of TRAF6 gene was evaluated using Real Time PCR and serum TNF-α level by ELISA method. Results: TRAF6 levels increased significantly after the two Training in the diabetic group, which was higher in the HIIT group and serum TNF-α levels decreased significantly after both types of training, which was more prominent in the HIIT group. Conclusion: HIIT and RT can play an important role in reducing the inflammatory factor of TNF-α in diabetic patient that HIIT is more effective in this regard. Increasing the gene expression of the mediating agent TRAF6 can be induced in inflammatory pathways, which may require a reduction in exercise intensity or in anti-inflammatory routes indicating a positive effect of training on diabetes.

Inter-Individual Different Responses to Continuous and Interval Training in Recreational Middle-Aged Women Runners.

A crucial subject in sports is identifying the inter-individual variation in response to training, which would allow creating individualized pre-training schedules, improving runner’s performance. We aimed to analyze heterogeneity in individual responses to two half-marathon training programs differing in running volume and intensity in middle-aged recreational women. 20 women (40 ± 7 years, 61 ± 7 kg, 167 ± 6 cm, and VO2max = 48 ± 6 mL⋅kg–1⋅min–1) underwent either moderate-intensity continuous (MICT) or high-intensity interval (HIIT) 12-week training. They were evaluated before and after training with maximal incremental tests in the laboratory (VO2max) and in the field (time to exhaustion, TTE; short interval series and long run). All the women participated in the same half-marathon and their finishing times were compared with their previous times. Although the improvements in the mean finishing times were not significant, MICT elicited a greater reduction (3 min 50 s, P = 0.298), with more women (70%) improving on their previous times, than HIIT (reduction of 2 min 34 s, P = 0.197, 50% responders). Laboratory tests showed more differences in the HIIT group (P = 0.008), while both groups presented homogeneous significant (P < 0.05) increases in TTE. Both in the short interval series and in the long run, HIIT induced better individual improvements, with a greater percentage of responders compared to MICT (100% vs 50% in the short series and 78% vs 38% in the long run). In conclusion, variability in inter-individual responses was observed after both MICT and HIIT, with some participants showing improvements (responders) while others did not (non-responders) in different performance parameters, reinforcing the idea that individualized training prescription is needed to optimize performance.

High-intensity Interval Versus Moderate-intensity Continuous Heated Water-based Exercise On Cardiovascular Variables In Hypertensive Older Individuals

PURPOSE: To evaluate acute hemodynamic and autonomic responses to high-intensity interval (HIIT) vs moderate-intensity continuous (MICE) exercise in heated water-based in older hypertensive individuals. METHODS: 15 sedentary older hypertensives were randomized in 2:2:1 to HIIT, MICE or without exercise (CON) sessions. Systolic/diastolic blood pressure (SBP/DBP), pulse wave velocity (PWV), endothelial function (EF) and variability of heart rate (HRV) were assessed before (pre), immediately after (post) and 45 min after intervention (rec). HIIT was consisted of warm-up (4 min), 21 min of 1 min of high-intensity alternating with 2 min of walking at moderate-intensity. MICE was performed by 4 min warm-up followed by 26 min of walking at moderate-intensity. Sessions were controlled using Rating Perceived of Exertion Scale (RPE).Two-way ANOVA (repeated measures) was used to indicate interventions differences and Bonferroni post hoc was used to identify significant differences (p<0.05). RESULTS: No significant differences were found for PWV and EF. HRV showed an increase in the μHP (high frequency band) when compared the moments PRE vs REC within CON group (PRE: 906 ± 132 ms vs REC: 942 ± 148 ms; p = 0.007). Moreover, even though POST-HIIT session we found a decrease of HFaHP (PRE: 413 ± 874 ms2 vs POST: 272 ± 716 ms2; p < 0.001), during REC only the HIIT group was able to increase the HFaHP index (POST: 272 ± 716 ms2 vs REC: 530 ± 1336 ms2; p < 0.001). The changes in HFaHP during REC was followed by a decreased of LFHP (low frequency band) index after HIIT (POST: 49 ± 24 n.u. vs REC: 33 ± 18 n.u.; p = 0.013). None difference was found in pre SBP/DBP (p>0.05). Although in post moment SBP was different between CON (153±4) vs MICE (141±6, p<0.02) and CON vs HIIT (136±5, p<0.001), with no difference in DBP. For REC, only CON (131±3) vs HIIT (123±4, p<0.02), with no difference in CON vs MICE and MICE vs HIIT (p>0.05) were founded. Only HIIT modality was able to return the SBP values to the PRE (122±4) in REC moment (123±4, p<0.66), but increasing in POST (136±5) moment comparing with PRE (p<0.01) and REC (p<0.02). For DBP, all intensities increase the values in POST (p<0.05) and maintain greater in REC moment comparing with pre (p<0.05). CONCLUSION: Water-based HIIT using RPE may be a time-efficient intervention in hypertension treatment of older individuals.

The effect of different types of exercise training on diet-induced obesity in rats, cross-talk between cell cycle proteins and apoptosis in testis.

Obesity is associated with germ cell apoptosis, spermatogenesis arrest, and testicular endocrine suppression. The aim of the present study was to investigate the crosstalk between germ cell apoptosis and cell cycle machinery in sedentary and obese rats after moderate-intensity continuous (MICT), high-intensity continuous (HICT) and High-intensity interval (HIIT) exercise trainings. Male Wistar rats (n= 30) were randomly divided into 5 groups; the control, sedentary high-fat diet (HFD)-received (HFD-sole), MICT, HICT and HIIT-induced HFD-received groups. The serum levels of LDL-C, HDL-C, triglyceride, and testosterone, mRNA and protein levels of Cyclin D1, Cdk4, p21, apoptotic cell number/mm2 of testicular tissue and testicular DNA fragmentation ratio were investigated. The obese animals in HFD-sole group represented a significant (p<0.05) reduction in serum HDL-C and testosterone levels, Cyclin D1, Cdk4 expressions, and exhibited a remarkable (p<0.05) increment in LDL-C, triglyceride, p21 expression, apoptotic cell number and DNA fragmentation ratio versus control animals. However, the animals in MICT, HICT, HIIT groups exhibited a significant (p<0.05) increment in serum HDL-C and testosterone, Cyclin D1 and Cdk4 expressions and showed a significant (p<0.05) reduction in serum LDL-C and triglyceride, p21 expression, apoptotic cell number and DNA fragmentation versus the HFD-sole group. In conclusion, a crosslink between cell cycle machinery and apoptosis of germ cells was revealed in the testicles of HFD-sole animals, and MICT, HICT and HIIT could ameliorate the obesity-induced impairments, respectively. This effect may be attributed to the effect of exercise training protocols on maintaining Cyclin D1 and Cdk4 and suppressing p21 expression levels in the testicles.

Effects of high-intensity interval and moderate-intensity continuous aerobic exercise on diabetic obese patients with nonalcoholic fatty liver disease: A comparative randomized controlled trial.

Background:Some studies assessed the effect of aerobic exercise on diabetic obese patients with hepatic disease, while very limited studies compared high-intensity interval (HII) versus moderate-intensity continuous (MIC) on diabetic obese patients with non-alcoholic fatty liver disease (NAFLD).Objectives:This study was designed to assess the effects of HII versus MIC on intrahepatic triglycerides (IHTG) and visceral lipids in diabetic obese patients with NAFLD.Design:Randomized controlled trial.Methods:Forty-seven diabetic obese individuals with NAFLD were enrolled in this study. The individuals were randomly divided into 16 in HII group, 15 in MIC group, and 16 in the controls. HII group received HII exercise, MIC group received 8-week MIC exercise while the control group did not receive any exercise intervention. IHTG and visceral lipids were assessed pre- and post-intervention.Results:Baseline and clinical characteristics showed nonsignificant difference among the 3 groups (P > .05). Both HII and MIC groups showed a significant reduction in hepatic fat and visceral lipids (P < .05), while the controls showed nonsignificant difference (P > .05) after completing the study intervention. Postintervention analysis showed nonsignificant changes between the HII and MIC groups (P > .05).Conclusions:Exercise training wither HII or MIC aerobic exercise reduces IHGT and visceral lipids in diabetic obese patients with NAFLD. No differences were observed between the effects of both exercise programs on diabetic obese patients with NAFLD.

Changes in Lipid Profile and C-Reactive Protein in Response to High Interval Intensity Training in Physically Active and Inactive Women

Background: High-intensity interval (HIIT) is a contributing factor to cardiovascular disease. Objectives: This study aimed to examine the effect of HIIT on lipid profile and C-reactive protein (CRP) in physically active (PhA) and physically inactive (PhI) women. Methods: Forty volunteer female students (20 PhA and 20 PhI) were selected and divided into 10-person groups of PhA (control and HIIT) and PhI (control and HIIT). During six weeks, the HIIT groups performed HIITs three sessions per week. Lipid profile and CRP levels of plasma were measured in the pretest and posttest. Results: We showed LDL, VLDL, and cholesterol were lower and HDL levels were higher in the PhA HIIT and PhI HIIT groups than in the PhA control group (P ≤ 0.05). Changes in CRP and TG levels were not significant in the PhA HIIT, PhI HIIT, and PhA control groups (P ≥ 0.05). Moreover, LDL, VLDL, and TG levels were lower and the HDL levels were higher in the PhI HIIT group than in the PhI control group (P ≤ 0.05). However, changes in CRP levels were not significant in the PhI HIIT group and PhI control group (P ≥ 0.05). Conclusions: It seems that HIIT can improve the lipid profile of PhA and PhI women, but further studies are necessary in this regard.

Comparing the effect of high intensity interval training and continuous training on BDNF, GDNF and NGF in hippocampus of C57BL/6 male mice

Introduction: Identifying the factors that influence on the uptake of Neurotrophins is an important goal for brain's health and function. There is some evidence that long-term exercise improves brain function. However, the effects of exercise intensities on the brain remain is unclear. Therefore, the purpose of this study was to compare the effects of high intensity interval (HIIT) and continuous training (CT) on neurotrophic factors gene expression in hippocampus of C57BL/6 mice.&#x0D; Methods: 30 C57BL/6 mice were randomly assigned to the following three groups: control (Con), interval training (IT), and continuous training (CT). The mice in the exercise group Were trained to run on the treadmill 5 sessions for 8 weeks. HIIT group performed protocol at 85-90% of maximal work rate for periods of 2 min alternating with 1 min intervals at 50-60% of maximal work rate. CT group performed a continuous exercise protocol at 70-75% of maximal work rate. The expression of BDNF, GDNF, and NGF genes was measured using the Real Time-PCR method in the hippocampus. For statistical analysis of the data was used from SPSS version 16 and the one-way ANOVA method.&#x0D; Results: The result showed that HIIT program significantly increased the mRNA levels of BDNF and GDNF in comparison with CT (p&lt;0.05), and mRNA level of NGF significantly increased in both groups while no significant differences were observed in NGF concentrations among the HIIT and CT groups (p&gt;0.05).&#x0D; Conclusion: Our results showed that HIIT had a more neuroprotective effect by improving the expression of the neurotrophin genes compared to the LICT in the hippocampus.

Tyre-pulling as concurrent training

Concurrent training has gained popularity as a health-promoting activity. The focus of this study was to investigate the feasibility of tyre-pulling as a strength and endurance training exercise. Thirty-four volunteered participants accepted to comply with an 8-week training program, and were by drawing lots divided into three groups: long-distance training, high-intensity interval training and control groups. The long-distance group exercised 60 min at 75–85% of HRmax three times a week. The high-intensity interval group also exercised three times a week with 10 intervals of 20 s and a rest of 10 s in an all-out intensity. The control group continued their ordinary activities. A test battery, measuring arm and leg strength, core strength, and endurance, were taken at the beginning and after 8 weeks. Anthropometric measurements and spirometry test were performed likewise. The high-intensity group had increased maximal oxygen uptake by 2.6 (2.2) mL kg−1 min−1. The number of repetitions in arm strength increased with 4.2 (3.5), for leg strength, the increase was 7.9 (9.2) repetitions. Leg strength increased in the long-distance group with 13.6 (14.7) repetitions and core strength increased with 30.3 (34.0), p ≤ 0.05. No significant changes were observed in the control group. Tyre-pulling is feasible for training endurance and strength at both low and high intensities.

Beneficial Autophagic Activities, Mitochondrial Function, and Metabolic Phenotype Adaptations Promoted by High-Intensity Interval Training in a Rat Model.

The effects of high-intensity interval (HIIT) and moderate-intensity continuous training (MICT) on basal autophagy and mitochondrial function in cardiac and skeletal muscle and plasma metabolic phenotypes have not been clearly characterized. Here, we investigated how 10-weeks HIIT and MICT differentially modify basal autophagy and mitochondrial markers in cardiac and skeletal muscle and conducted an untargeted metabolomics study with proton nuclear magnetic resonance (1H NMR) spectroscopy and multivariate statistical analysis of plasma metabolic phenotypes. Male Sprague–Dawley rats were separated into three groups: sedentary control (SED), MICT, and HIIT. Rats underwent evaluation of exercise performance, including exercise tolerance and grip strength, and blood lactate levels were measured immediately after an incremental exercise test. Plasma samples were analyzed by 1H NMR. The expression of autophagy and mitochondrial markers and autophagic flux (LC3II/LC3-I ratio) in cardiac, rectus femoris, and soleus muscle were analyzed by western blotting. Time to exhaustion and grip strength increased significantly following HIIT compared with that in both SED and MICT groups. Compared with those in the SED group, blood lactate level, and the expression of SDH, COX-IV, and SIRT3 significantly increased in rectus femoris and soleus muscle of both HIIT and MICT groups. Meanwhile, SDH and COX-IV content of cardiac muscle and COX-IV and SIRT3 content of rectus femoris and soleus muscle increased significantly following HIIT compared with that following MICT. The expression of LC3-II, ATG-3, and Beclin-1 and LC3II/LC3-I ratio were significantly increased only in soleus and cardiac muscle following HIIT. These data indicate that HIIT was more effective for improving physical performance and facilitating cardiac and skeletal muscle adaptations that increase mitochondrial function and basal autophagic activities. Moreover, 1H NMR spectroscopy and multivariate statistical analysis identified 11 metabolites in plasma, among which fine significantly and similarly changed after both HIIT and MICT, while BCAAs isoleucine, leucine, and valine and glutamine were changed only after HIIT. Together, these data indicate distinct differences in specific metabolites and autophagy and mitochondrial markers following HIIT vs. MICT and highlight the value of metabolomic analysis in providing more detailed insight into the metabolic adaptations to exercise training.

COMPARISON OF HIGH INTENSITY INTERVAL TO MODERATE INTENSITY CONTINUOUS AEROBIC EXERCISE ON VENTILATORY MARKERS IN CORONARY HEART DISEASE PATIENTS: A RANDOMIZED CONTROLLED STUDY

Objectives: This study aim was to compare the impacts of the high-intensity interval (HII) to moderate-intensity continuous exercise (MIC) on ventilatory markers in patients with coronary heart disease (CHD). Design: Twenty-eight patients with mild to moderate CHD aged 50-60 years were selected for this study. They randomized to two groups, each group comprised of 14 patients, group I received a program of high-intensity interval exercise (HII 3 times/week for 12 weeks) and group II received a program of moderate-intensity continuous aerobic exercise (MIC 3 times/week for 12 weeks). The ventilatory marker changes (O2P, slope of VE/VCO2 and OUES) have been measured at the beginning and the end of the study. Result: After 12 weeks of enrollment, HII group showed statistically significant improvement in O2P but no significant changes in MIC group (21% with p 0.05). No significant differences appeared in VE/VCO2 and OUES (pre- and post-program) in the two groups p>0.05. Conclusions: It was concluded that HII had greater improvements than MIC on ventilatory markers in patients with CHD in a short-term (up to twelve weeks).

High-intensity interval training has positive effects on performance in ice hockey players.

In spite of the well-known benefits that have been shown, few studies have looked at the practical applications of high-intensity interval training (HIIT) on athletic performance. This study investigated the effects of a HIIT program compared to traditional continuous endurance exercise training. 24 hockey players were randomly assigned to either a continuous or high-intensity interval group during a 4-week training program. The interval group (IG) was involved in a periodized HIIT program. The continuous group (CG) performed moderate intensity cycling for 45-60 min at an intensity that was 65% of their calculated heart rate reserve. Body composition, muscle thickness, anaerobic power, and on-ice measures were assessed pre- and post-training. Muscle thickness was significantly greater in IG (p=0.01) when compared to CG. The IG had greater values for both ∆ peak power (p<0.003) and ∆ mean power (p<0.02). Additionally, IG demonstrated a faster ∆ sprint (p<0.02) and a trend (p=0.08) for faster ∆ endurance test time to completion for IG. These results indicate that hockey players may utilize short-term HIIT to elicit positive effects in muscle thickness, power and on-ice performance.

Effects of High- and Moderate-Intensity Training on Metabolism and Repeated Sprints

We compared the effects of high-intensity interval (HIT) and moderate-intensity continuous (MIT) training (matched for total work) on changes in repeated-sprint ability (RSA) and muscle metabolism. Pre- and posttraining, VO(2peak), lactate threshold (LT), and RSA (5 x 6-s sprints, every 30 s) were assessed in 20 females. Before and immediately after the RSA test, muscle biopsies were taken from the vastus lateralis. Subjects were matched on RSA, randomly placed into the HIT (N = 10) or MIT (N = 10) group and performed 5 wk (3 d.wk(-1)) of cycle training; performing either HIT (6-10, 2-min intervals at 120-140% LT) or MIT (continuous, 20-30 min at 80-95% LT). Both groups had significant improvements in VO(2peak) (10-12%; P < 0.05) and LT (8-10%; P < 0.05), with no significant differences between them. Both groups also had significant increases in RSA total work (kJ) (P < 0.05), with a significantly greater increase following HIT than MIT (13 vs 8.5%, respectively; P < 0.05). There was a significant decrease in resting [ATP] and an increase in postexercise [La(-)](b) for both groups, but no significant differences between them. There were no significant changes in resting or postexercise [PCr], [Cr], muscle [La(-)], or [H(+)] after the training period. When total work is matched, HIT results in greater improvements in RSA than MIT. This results from an improved ability to maintain performance during consecutive sprints, which is not explained by differences in work done during the first sprint, aerobic fitness or metabolite accumulation at the end of the sprints.

A COMPARISON OF INTERVAL VS. STEADY-STATE EXERCISE ON SUBSTRATE UTILIZATION IN OVERWEIGHT WOMEN

PURPOSE: This study investigated changes in substrate utilization during exercise following 8 weeks of interval versus steady-state training in 15 obese women. (Age: 33.8 ± 8.2 yr; HT: 165.7 ± 6.8 cm; WT: 88.0 ± 21.4 kg; BMI: 31.8 ± 6.6 kg/m2; % body fat: 42.9 ± 6.8%). METHODS: Subjects were randomized to either a high intensity interval group (IT (n = 7): 2 minutes at 95% of VO2 max alternating with 3 minutes of 25% of VO2 max) or a lower intensity steady state training group (ST (n = 8): 50% of VO2 max). There were no statistical differences between the IT and ST group prior to training in fitness or body composition. During training, each group was monitor by indirect calorimetry so they had the same mean intensity, duration, and caloric expenditure (300 kcals) during the workouts. VO2 (1/min and ml/kg/min), kcal/min, kcal/min/kgBW, and kcal/min/kgFFW were calculated at specific RER values 0.80, 0.85, 0.90, 0.95, and 1.00 both prior to and following training. RESULTS: The results indicated, that despite similar average exercise training intensities, only the IT group showed significant improvements after training. Using the 0.85 RER value (The cross-over point for fat to CHO usage), the IT showed a significant increase in VO2 (13.59 ± 3.85 to 16.53 ± 2.70 ml/kg/min; p < 0.05), kcal/min/kgBW (0.066 ± 0.18 to 0.081 ± 0.013; p < 0.05), and kcal/min/kgFFW (0.113 ± 0.026 to 0.143 to 0.018; p = 0.01) and trends toward significance in absolute VO2 (1.21 ± 0.26 to 1.49 ± 0.28 L/min; p = 0.08) & kcal/min (5.88 ± 1.27 to 7.26 ± 1.35; p = 0.08). Similar improvements were observed at 0.90 and 1.0 RER values. In contrast, no significant changes were found in the ST group. CONCLUSIONS: These results suggest that high intensity interval training independent of total workload, significantly improved caloric expenditure at a given RER value. Consequently, a significant increase in absolute fat utilization during submaximal exercise resulted which lead to improvements in fat losses in the IT group as we've previously reported (King, 2001 ACSM annual meeting).