High-intensity Intermittent Exercise Training Research Articles

Combined effects of intermittent fasting with swimming-based high intensity intermittent exercise training in Wistar rats

High caloric intake and physical inactivity are known precursors to the development of several chronic metabolic diseases. For obesity and sedentarism, High Intensity Intermittent Exercise (HIIE) and Intermittent Fasting (IF) have emerged as individual strategies to attenuate their negative effects by improving metabolism. To study their combined effects, Wistar male rats (n = 74, 60 days old) were divided into four groups: Sedentary Control (C), swimming-based HIIE only (HIIE), Intermittent Fasting only (IF), and swimming-based HIIE associated with Intermittent Fasting (HIIE/IF). Over an eight-week period swimming performance, body composition, weight and feeding behavior were analyzed. The final morphology of white adipose tissue showed a significant reduction in adipocyte size consistent with a higher number of cells per area in exercised animals (vs C and IF, p < 0.05), which also displayed characteristics of browning through UCP-1 levels and CD31 staining. These results suggest that the increased performance in the HIIE/IF group is, in part, by modifications of WAT metabolism through the browning process.

Effect of 8-week high-intensity intermittent running exercise and weight training on muscle and DNA damage in male and female ski major college students.

This study assessed changes in blood muscle damage indicators and DNA damage indicators in lymph and urine after 8 weeks of high-intensity intermittent running and weight training in male and female college students majoring in skiing. This study aimed to find an effective training method by investigating differences in the effectiveness between men and women. A total of 20 male and female ski major college students conducted short-term high-intensity intermittent running and weight training in the morning and afternoon, respectively, 3 days a week for 8 weeks for 24 times in total. After 8 weeks of high-intensity intermittent running and weight training, changes in DNA damage indicators in the lymph and urine and muscle damage indicators in the blood were analyzed. The creatine kinase level significantly differed at rest pre-graded exercise testing (GXT) and 60 min of recovery post-GXT after training from that before training between the male and female groups. Although lactate dehydrogenase (LDH) levels decreased in both groups over time, no significant differences in LDH were found between the two groups. Second, DNA 8-hydroxydeoxyguanosine (8-OHdG) in the lymph was significantly different between the two groups at rest pre-GXT and 60 min of recovery post-GXT. 8-OHdG in the urine was significantly lower in the female group only at 60 min of recovery post-GXT. Partial sex differences were found in the reduction of muscle damage and DNA damage after 8 weeks of high-intensity intermittent running and weight training.

Effects of Different Intensity Exercise on the Patients of Oxidative Stress Factors and Glycemic Control Type 2 Diabetes Mellitus

This study’s major purpose was to examine the impact of two various exercise intensities on glucagon-like peptide-1 and endoplasmic reticulum stress in teenagers with type 2 diabetes. Twenty teenagers with T2DM were recruited in the trial and randomly assigned to one of two groups: HIT (n = 10) or LIT (n = 10). At a heart rate of less than 45 percent, the low-intensity intense exercise group participated in aerobic activity training. Interval training with a heart rate reserve of at least 80% was used by the high-intensity intermittent training group. Both groups had the same weekly energy expenditure (1,200 kcal/week). The nositol required enzyme 1 and X-box binding protein-1 improved in both groups, but the difference in improvement between the two groups was not statistically significant. High-intensity interval training led to a significant decrease in body fat percentage among participants. After 12 weeks, the C-peptide levels had risen and varied considerably between the two groups. According to the homeostasis model assessment, there were significant differences between the groups in fasting glucose and insulin resistance, and leptin levels reduced after 12 weeks. The 12-week rise in glucagon-like peptide-1 was different across the groups. In teenagers with type 2 diabetes mellitus, high-intensity intermittent exercise training may enhance glycemic management, physical body composition, glucagon-like peptide-1, and endoplasmic reticulum stress.

MiR‑29 mediates exercise‑induced skeletal muscle angiogenesis by targeting VEGFA, COL4A1 and COL4A2 via the PI3K/Akt signaling pathway.

The present study investigated the molecular changes and related regulatory mechanisms in the response of skeletal muscle to exercise. The microarray dataset ‘GSE109657’ of the skeletal muscle response to high-intensity intermittent exercise training (HIIT) was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened and analyzed using weighted gene co-expression network analysis (WGCNA) to identify the significant functional co-expressed gene modules. Moreover, functional enrichment analysis was performed for the DEGs in the significant modules. In addition, protein-protein interaction (PPI) network and microRNA (miR)-transcription factor (TF)-target regulatory network were constructed. A total of 530 DEGs in the skeletal muscle were screened after HIIT, suggesting an effect of HIIT on the skeletal muscle. Moreover, three significant modules (brown, blue and red modules) were identified after WGCNA, and the genes Collagen Type IV α1 Chain (COL4A1) and COL4A2 in the brown module showed the strongest correlation with HIIT. The DEGs in the three modules were significantly enriched in focal adhesion, extracellular matrix organization and the PI3K/Akt signaling pathway. Furthermore, the PPI network contained 104 nodes and 211 interactions. Vascular endothelial growth factor A (VEGFA), COL4A1 and COL4A2 were the hub genes in the PPI network, and were all regulated by miR-29a/b/c. In addition, VEGFA, COL4A1 and COL4A2 were significantly upregulated in the skeletal muscle response to HIIT. Therefore, the present results suggested that the growth and migration of vascular endothelial cells, and skeletal muscle angiogenesis may be regulated by miR-29a/b/c targeting VEGFA, COL4A1 and COL4A2 via the PI3K/Akt signaling pathway. The present results may provide a theoretical basis to investigate the effect of exercise on skeletal muscle.

Interleukin-15 and creatine kinase response to high-intensity intermittent exercise training

To verify the acute and chronic effects of high-intensity intermittent training (HIIT) on interleukin 15 (IL-15) response and the relationship between circulating IL-15 concentrations and muscle damage in young men. Physically active men performed two different training protocols at moderate and high intensity, three times per week for 5 weeks. Twenty subjects were randomly allocated into high-intensity intermittent training group (HIIT-5 km 1 min at 100% of maximal aerobic speed interspersed by 1 min passive recovery; n = 10) or moderate-intensity continuous training group (MICT-5 km 70% of maximal aerobic speed; n = 10). An acute exercise session was performed with blood sample collection pre-exercise, immediately post-exercise, and 60 min post-exercise (before and after 5 weeks of training). Blood samples were used to analyze serum IL-15 and creatine kinase (CK) concentrations. The results showed no changes in serum IL-15 concentrations independent of protocol, moment measurement, and intervention period. CK concentrations showed higher values post-exercise when compared to pre-exercise in both protocols. No significant relationship was found between serum IL-15 and CK concentrations. Our findings point to the absence of acute and chronic changes in serum IL-15 concentrations in response to 5 weeks of high-intensity intermittent training. In addition, data suggest that the release of this cytokine is not related to muscle damage in healthy young men.

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)

High-intensity intermittent training is as effective as moderate continuous training, and not deleterious, in cardiomyocyte remodeling of hypertensive rats.

Exercise training offers possible nonpharmacological therapy for cardiovascular diseases including hypertension. High-intensity intermittent exercise (HIIE) training has been shown to have as much or even more beneficial cardiovascular effect in patients with cardiovascular diseases than moderate-intensity continuous exercise (CMIE) training. The aim of this study was to investigate the effects of the two types of training on cardiac remodeling of spontaneously hypertensive rats (SHR) induced by hypertension. Eight-week-old male SHR and normotensive Wistar-Kyoto rats (WKY) were divided into four groups: normotensive and hypertensive control (WKY and SHR-C) and hypertensive trained with CMIE (SHR-T CMIE) or HIIE (SHR-T HIIE). After 8 wk of training or inactivity, maximal running speed (MRS), arterial pressure, and heart weight were all assessed. CMIE or HIIE protocols not only increased final MRS and left ventricular weight/body weight ratio but also reduced mean arterial pressure compared with sedentary group. Then, left ventricular tissue was enzymatically dissociated, and isolated cardiomyocytes were used to highlight the changes induced by physical activity at morphological, mechanical, and molecular levels. Both types of training induced restoration of transverse tubule regularity, decrease in spark site density, and reduction in half-relaxation time of calcium transients. HIIE training, in particular, decreased spark amplitude and width, and increased cardiomyocyte contractility and the expression of sarco(endo)plasmic reticulum Ca2+-ATPase and phospholamban phosphorylated on serine 16. NEW & NOTEWORTHY High-intensity intermittent exercise training induces beneficial remodeling of the left ventricular cardiomyocytes of spontaneously hypertensive rats at the morphological, mechanical, and molecular levels. Results also confirm, at the cellular level, that this type of training, as it appears not to be deleterious, could be applied in rehabilitation of hypertensive patients.

Gene expression profile of muscle adaptation to high-intensity intermittent exercise training in young men

High-intensity intermittent exercise training (HIIT) has been proposed as an effective approach for improving both, the aerobic and anaerobic exercise capacity. However, the detailed molecular response of the skeletal muscle to HIIT remains unknown. We examined the effects of the HIIT on the global gene expression in the human skeletal muscle. Eleven young healthy men participated in the study and completed a 6-week HIIT program involving exhaustive 6–7 sets of 20-s cycling periods with 10-s rests. In addition to determining the maximal oxygen uptake ({dot{{rm{V}}}{rm{O}}}_{2{rm{max }}}), maximal accumulated oxygen deficit, and thigh muscle cross-sectional area (CSA), muscle biopsy samples were obtained from the vastus lateralis before and after the training to analyse the skeletal muscle transcriptome. The HIIT program significantly increased the {dot{{rm{V}}}{rm{O}}}_{2{rm{max }}}, maximal accumulated oxygen deficit, and thigh muscle CSA. The expression of 79 genes was significantly elevated (fold-change >1.2), and that of 73 genes was significantly reduced (fold-change <0.8) after HIIT. Gene ontology analysis of the up-regulated genes revealed that the significantly enriched categories were “glucose metabolism”, “extracellular matrix”, “angiogenesis”, and “mitochondrial membrane”. By providing information about a set of genes in the human skeletal muscle that responds to the HIIT, the study provided insight into the mechanism of skeletal muscle adaptation to HIIT.

A Mechanism Underlying Preventive Effect of High-Intensity Training on Colon Cancer.

We examined effects of high-intensity training on chemically induced aberrant crypt foci (ACF) in rat colon. We also investigated mechanisms that may underlie the results obtained, with a focus on secreted protein acidic and rich in cysteine (SPARC), which has been proposed as an exercise-related factor of colon cancer prevention. After an administration of 1,2-dimethylhydrazine, F344 rats executed high-intensity intermittent swimming training (HIIST) (twelve 20-s swimming with a weight [16% body weight] with 10-s pauses between the bouts) 5 d·wk for 4 wk. The acute and chronic effects of the HIIST on SPARC were evaluated in rats. We evaluated the in vitro and in vivo effects of 5' AMP-activated protein kinase (AMPK) activator on SPARC in rat serum and epitrochlearis muscle. In human subjects, we determined serum SPARC after exhaustive bicycling consisting of six to seven bouts of exercise at 170% V˙O2max with 10-s rests between the bouts (high-intensity intermittent bicycling [HIIB]). The SPARC mRNA in human vastus lateralis was measured before and after the HIIB for 4 d·wk for 6 wk (HIIB-training [HIIBT]). The numbers of ACF were lower in the HIIST (47 ± 22) compared with the control (122 ± 47) rats (P < 0.05). SPARC in epitrochlearis and serum after HIIS of the trained rat was higher than that in the control resting rats. In vitro and vivo AMPK stimulation increased mRNA and SPARC protein in rat epitrochlearis, respectively. The human serum SPARC after the HIIB was elevated. SPARC mRNA in human muscle was elevated after the HIIBT. The results demonstrated that HIIST inhibits 1,2-dimethylhydrazine-induced colon ACF development. This effect may be explained by SPARC induction by the exercise intensity-related factor AMPK, potentially explaining the preventive effects of high-intensity intermittent exercise training against colon cancer.

High Intensity Intermittent Training And Chlorella Intake Enhance Muscle Glycolytic And Oxidative Metabolism In Rats.

Chronic chlorella intake enhances aerobic exercise capacities, i.e. exercise tolerance. High intensity intermittent exercise (HIIE) training enhances aerobic and anaerobic exercise capacities via elevation of muscle glycolytic and oxidative metabolism. However, the additive effects of combination of HIIE training and chlorella intake on exercise performance and muscle glycolytic and oxidative metabolism remain unclear. PURPOSE: The purpose of this study was to investigate the effect of chronic chlorella intake alone or in combination with HIIE training on exercise performance and muscle glycolytic and oxidative metabolism in rats. METHODS: Male 12-week-old Sprague-Dawley rats were randomly assigned to the four groups; sedentary control, chlorella intake (0.5% chlorella powder in normal feed), HIIE training, and combination of HIIE training and chlorella intake for 6 weeks (n = 10 each group). HIIE training comprised 14 repeats of a 20-s swimming session with a 10-s pause between sessions, while bearing a weight equivalent to 16% of body weight, 4 days/week. Exercise performance was tested after the interventions by measuring the maximal number of HIIE sessions that could be completed. RESULTS: Chlorella intake and HIIE training significantly increased the maximal number of HIIE, and enhanced the expression of monocarboxylate transporter (MCT)1, MCT4, and peroxisome proliferator activated receptor γ coactivator-1α concomitantly with the activities of lactate dehydrogenase (LDH), phosphofructokinase, citrate synthase (CS), and cytochrome oxidase (COX) in the red region of the gastrocnemius muscle (p<0.05). Furthermore, the combination further augmented the increased exercise performance and the enhanced expressions and activities (p<0.05). By contrast, in the white region of the gastrocnemius muscle, MCT1 expression and LDH, CS, and COX activities did not change. CONCLUSIONS: These results showed that compared to only chlorella intake and only HIIE training, chlorella intake combined with HIIE training has a more pronounced effect on exercise performance and muscle glycolytic and oxidative metabolism, in particular lactate metabolism. Supported by Grants-in-Aid for Scientific Research (#26282199, M. Iemitsu)

High-intensity intermittent exercise training with chlorella intake accelerates exercise performance and muscle glycolytic and oxidative capacity in rats.

The purpose of this study was to investigate the effect of chronic chlorella intake alone or in combination with high-intensity intermittent exercise (HIIE) training on exercise performance and muscle glycolytic and oxidative metabolism in rats. Forty male Sprague-Dawley rats were randomly assigned to the four groups: sedentary control, chlorella intake (0.5% chlorella powder in normal feed), HIIE training, and combination of HIIE training and chlorella intake for 6 wk (n = 10 each group). HIIE training comprised 14 repeats of a 20-s swimming session with a 10-s pause between sessions, while bearing a weight equivalent to 16% of body weight, 4 days/week. Exercise performance was tested after the interventions by measuring the maximal number of HIIE sessions that could be completed. Chlorella intake and HIIE training significantly increased the maximal number of HIIE sessions and enhanced the expression of monocarboxylate transporter (MCT)1, MCT4, and peroxisome proliferator-activated receptor γ coactivator-1α concomitantly with the activities of lactate dehydrogenase (LDH), phosphofructokinase, citrate synthase (CS), and cytochrome-c oxidase (COX) in the red region of the gastrocnemius muscle. Furthermore, the combination further augmented the increased exercise performance and the enhanced expressions and activities. By contrast, in the white region of the muscle, MCT1 expression and LDH, CS, and COX activities did not change. These results showed that compared with only chlorella intake and only HIIE training, chlorella intake combined with HIIE training has a more pronounced effect on exercise performance and muscle glycolytic and oxidative metabolism, in particular, lactate metabolism.

災害弱者である子どもに対する運動介入の重要性

災害弱者である子どもに対する運動介入の重要性

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.

Effects of hypobaric hypoxia and voluntary hypocapnic hyperventilation on metabolic response during high-intensity intermittent exercise

To improve performance of short time high-intensity exercise, it is important to enhance anaerobic energy systems. High intensity intermittent exercise training stresses the anaerobic energy systems in order for improvements to occur. In addition, it is suggested that high intensity intermittent exercise under hypobaric hypoxia (HX) as well as reductions in arterial CO2 pressure (hypocapnia: HC) induced by voluntary hyperventilation could enhance anaerobic metabolic rate more effectively [1]. However, it is unclear whether the effects on anaerobic metabolic rate differ between HX and HC. Therefore, the purpose of this study was to investigate whether HX and HC have similar effects on metabolic response during high intensity intermittent exercise.

Much potential but many unanswered questions for high-intensity intermittent exercise training for patients with heart failure.

There is a robust trove of scientific studies that support the positive physical and mental health benefits associated with aerobic exercise for healthy individuals. These recommendations suggest that more vigorous exercise can be performed on fewer days for the same benefit. High-intensity intermittent exercise (HIIE) training has begun to show promise. HIIE seems safe and improves physiology, quality of life, and functional capacity. This review defines HIIE, discusses its physiologic benefit for patients with heart failure, outlines the studies that have been conducted to date, and places it in the context of the current clinical environment of exercise training for these patients.

High-Intensity Intermittent Exercise Training for Cardiovascular Disease

Exercise training is widely recommended in health and some conditions diseases. It is well established that physical active behaviour is related to decrease in cardiovascular diseases and consequently longer life expectancy. Talking about exercise training involves some methodological approaches such as type of exercise, volume, duration, frequency and intensity; and intensity is exactly what this review is focused, especially high-intensity intermittent exercise training, also known as interval training. Prescribing this model of training according to literature makes it difficult to reach a consensus about the methodology and true effects of it, especially for cardiac patients. For that reason, the aim of this review is to present the current context about the different types of high-intensity intermittent exercise training, its benefits and risks compared to endurance training in some diseases such as coronary artery disease and chronic heart failure.

The impact of high-intensity intermittent exercise on resting metabolic rate in healthy males

High-intensity intermittent exercise training (HIT) may favourably alter body composition despite low training volumes and predicted energy expenditure (EE). To characterise the acute impact of two common HIT protocols on EE and post-exercise oxygen consumption (11h EPOC). Oxygen consumption (lmin(-1)), respiratory exchange ratio (RER) and EE were measured in nine healthy, lean males over 12h under three conditions: control (CON), HIT1 (10×1min high-intensity cycling bouts followed by 1min rest) and HIT2 (10×4min high-intensity cycling bouts followed by 2min rest). Total exercise period EE during HIT1 (1,151±205kJ) (mean±SD) was significantly lower than HIT2 (2,788±322kJ; p<0.001). EE within the 60min after exercise was significantly albeit marginally higher after HIT1 (388±44kJ; p=0.02) and HIT2 (389±39kJ; p=0.01) compared with CON (329±39kJ), with no difference between exercise conditions (p=0.778). RER during this period was significantly lower in HIT1 (0.78±0.06; p=0.011) and HIT2 (0.76±0.04; p=0.004) compared with CON (0.87±0.06). During the 'slow phase' of EPOC (1.25-9.75h), there were no significant differences in EE (p=0.07) or RER (p=0.173) between trials. Single HIT sessions notably increases EE during exertion; however, the influence on metabolic rate post-exercise is transient and relatively minor.

Rating of Perceived Exertion after 12 Weeks of High-Intensity, Intermittent Sprinting

The effect of a 12-week high-intensity intermittent exercise (HIIE) intervention on the rating of perceived exertion (RPE) response of young males was examined. Participants (N = 38; M BMI = 28.7 kg x m(-2), SD = 3.1; M age = 24.9 yr., SD = 4.3) were randomly assigned to either an exercise or control group. The exercise group received HIIE three times per week, 20 min. per session, for 12 weeks. RPE was assessed before and after HIIE training and during pre- and post-maximal oxygen uptake (VO2 max) testing. After HIIE training, RPE was significantly higher in Weeks 11-12 compared to Weeks 1-2. In contrast, heart rate was similar throughout training. Comparing post- to pre-VO2 max test, RPE was significantly lower in the exercise group, whereas for controls, RPE was similar. Aerobic power improved 15% for the exercise group, with no significant change for controls. HIIE resulted in significant increases in RPE, whereas RPE during the VO2 max test was significantly decreased.

The effects of high-intensity intermittent exercise training on cardiovascular response to mental and physical challenge

The purpose was to examine the effect of a 12-week exercise intervention on the cardiovascular and autonomic response of males to mental and physical challenge. Thirty four young overweight males were randomly assigned to either an exercise or control group. The exercise group completed a high-intensity intermittent exercise (HIIE) program three times per week for 12weeks. Cardiovascular response to the Stroop task was determined before and after the intervention by assessing heart rate (HR), stroke volume (SV), arterial stiffness, baroreflex sensitivity (BRS), and skeletal muscle blood flow. The exercise group improved their aerobic fitness levels by 17% and reduced their body weight by 1.6kg. Exercisers compared to controls experienced a significant reduction in HR (p<0.001) and a significant increase in SV (p<0.001) at rest and during Stroop and exercise. For exercisers, arterial stiffness significantly decreased at rest and during Stroop (p<0.01), whereas BRS was increased at rest and during Stroop (p<0.01). Forearm blood flow was significantly increased during the first two minutes of Stroop (p<0.05). HIIE induced significant cardiovascular and autonomic changes at rest and during mental and physical challenge after 12weeks of training.

The relationship between heart period variability and VO 2 peak response to high intensity intermittent exercise training

Introduction: Significant individual differences in the VO2max response to regular aerobic training have been documented in healthy adults after standardized exercise programs. In prior research the mean improvements in VO2max have ranged from a 5% decrease to a 40% increase. Recently, baseline autonomic nervous system status has been shown to be a contributor to the training response. High frequency power of heart period variability (HPV), a measure of vagal influence on the heart, has been shown to predict training response independently after adjustment for age, baseline fitness, and BMI.