Moderate-intensity Interval Exercise Research Articles

Moderate-Intensity and High-Intensity Interval Exercise Training Offer Equal Cardioprotection, with Different Mechanisms, during the Development of Type 2 Diabetes in Rats.

Endurance exercise training is a promising cardioprotective strategy in type 2 diabetes mellitus (T2DM), but the impact of its intensity is not clear. We aimed to investigate whether and how isocaloric moderate-intensity exercise training (MIT) and high-intensity interval exercise training (HIIT) could prevent the adverse cardiac remodeling and dysfunction that develop T2DM in rats. Male rats received a Western diet (WD) to induce T2DM and underwent a sedentary lifestyle (n = 7), MIT (n = 7) or HIIT (n = 8). Insulin resistance was defined as the HOMA-IR value. Cardiac function was assessed with left ventricular (LV) echocardiography and invasive hemodynamics. A qPCR and histology of LV tissue unraveled underlying mechanisms. We found that MIT and HIIT halted T2DM development compared to in sedentary WD rats (p < 0.05). Both interventions prevented increases in LV end-systolic pressure, wall thickness and interstitial collagen content (p < 0.05). In LV tissue, HIIT tended to upregulate the gene expression of an ROS-generating enzyme (NOX4), while both modalities increased proinflammatory macrophage markers and cytokines (CD86, TNF-α, IL-1β; p < 0.05). HIIT promoted antioxidant and dicarbonyl defense systems (SOD2, glyoxalase 1; p < 0.05) whereas MIT elevated anti-inflammatory macrophage marker expression (CD206, CD163; p < 0.01). We conclude that both MIT and HIIT limit WD-induced T2DM with diastolic dysfunction and pathological LV hypertrophy, possibly using different adaptive mechanisms.

Lipid Peroxidation Level on Moderate-Intensity Interval Exercise on Non-Athlete Adolescent

Exercise is commonly perceived as a pleasurable and healthy activity. However, it is classified as a complex activity that potentially enhances the formation of free radicals and oxidative stress. This study aims to analyze lipid peroxidation, as the biomarker of free radicals, in interval exercise. A total of 16 trained non-athlete male adolescents, aged 20-21 years old, with normal blood pressure, normal resting heart rate, and gave good level of physical fitness voluntarily participated in this study. The participants were randomly separated into two groups, namely the K1 (n=8, interval exercise with active resting medium intensity pedaling ergometer bike) and K2 (n=8, interval exercise with resting without pedaling the ergometer bike). The interval exercise was carried out at 60-70% HRmax intensity for 35 minutes. The blood sample for Malondialdehyde (MDA) level analysis, as the lipid peroxidation biomarker, was taken using Thiobarbituric acid reactive substances (TBARS). The blood samples were collected before and after the interval exercise. The obtained data were analyzed using the one-way ANOVA test with a 5% significance level. Our results suggest no significant different level of MDA, a lipid peroxidation biomarker, between the interval exercise with resting through medium intensity pedaling ergometer bike and the interval exercise with resting with no pedaling ergometer bike. However, the interval exercise resting through pedaling an ergometer bike presented relatively higher lipid peroxidation than the interval exercise resting without pedaling an ergometer bike. Therefore, following the free radical concept, interval exercise with resting through pedaling an ergometer bike is more beneficial than the exercise without pedaling an ergometer bike resting.

Dynamic alteration of plasma levels of betatrophin in younger female onset obesity post acute moderate-intensity exercise training

Obesity is a global metabolic disease anchored by a lack of physical activity lipid disturbances. Hitherto, betatrophin is a potential liver-derived hormone that regulates lipid metabolism. A total of 26 selected onset obese individuals (BMI range ± 28–31) were enrolled in this study and given moderate-intensity exercise. Importantly, our data show that acute moderate-intensity interval exercise (MIIE) and acute moderate-intensity continue to exercise (MICE) for 40 min significantly decrease the plasma level of full-length betatrophin respectively (174.18 ± 48.19 ng/mL; 182.31 ± 52.69 ng/mL), compared to the placebo (283.97 ± 32.23 ng/mL) post 10 min and 6 h exercise treatment (p ≤ 0.05). The plasma level of betatrophin was significantly and negatively correlated with BMI (r = − 0.412, p = 0.037), fasting blood glucose (r = − 0.390, p = 0.049), and positively correlated with VO2max (r = 0.456, p = 0.019). In addition, the linear and ordinal logistic regression analysis shows that betatrophin, is a potential predictor for BMI [estimate value = 0.995, p = 0.037 and OR (95 % CI) = 0.992 (0.0984–1.00), p = 0,048]. In summary, our data demonstrate that the circulating levels of betatrophin were decreased after acute moderate-intensity exercise training.

Effects of Acute Exercise on Cardiac Autonomic Response and Recovery in Non-Dialysis Chronic Kidney Disease Patients

ABSTRACT Purpose: Heart rate variability (HRV) has gained acceptance as a key marker of cardiovascular health. We compared HRV responses after continuous moderate-intensity exercise (CMIE) and high-intensity interval exercise (HIIE) matched for intensity and duration in individuals with midspectrum chronic kidney disease (CKD). Methods: Twenty men and women (age 62.0 ± 10 yrs.) diagnosed with CKD stages G3a and G3b participated in a 2 (condition) x 4 (time point) repeated cross-over measures design study. HRV time-domain indices were based on the standard deviation of all NN intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD) and frequency domain. High-frequency (HF), low-frequency (LF), total power (TP) were examined. CMIE consisted of treadmill walking for 30 minutes at a 2% incline and speed corresponding to 60%–65% of reserve volume of oxygen (VO2R). HIIE included five intervals of 3 minutes at 90% of VO2R and 2 minutes at 20% VO2R intervals. Conditions were designed to be of the same average intensity (60% to 65% of VO2R) and caloric expenditure (~144 kcal). Results: Immediately following exercise SDNN, RMSSD, HF, LF, and TP were significantly lower compared to before exercise (p <.05). HRV responses were not different between conditions and conditions X time (p >.05). Conclusions: Thirty minutes of either CMIE or HIIE decreased HRV indices, pointing to an autonomic imbalance favoring vagal mediation. HRV’s responses regarding HIIE were no different from CMIE, therefore, from an autonomic function point of view this similarity may be useful for CKD exercise prescription and programming.

Acute aerobic exercise-conditioned serum reduces colon cancer cell proliferation in vitro through interleukin-6-induced regulation of DNA damage.

Epidemiological evidence shows that regular physical activity is associated with reduced risk of primary and recurrent colon cancer. However, the underlying mechanisms of action are poorly understood. We evaluated the effects of stimulating a human colon cancer cell line (LoVo) with human serum collected before and after an acute exercise bout vs nonexercise control serum on cancer cell proliferation. We also measured exercise‐induced changes in serum cytokines and intracellular protein expression to explore potential biological mechanisms. Blood samples were collected from 16 men with lifestyle risk factors for colon cancer (age ≥50 years; body mass index ≥25 kg/m2; physically inactive) before and immediately after an acute bout of moderate‐intensity aerobic interval exercise (6 × 5 minutes intervals at 60% heart rate reserve) and a nonexercise control condition. Stimulating LoVo cells with serum obtained immediately after exercise reduced cancer cell proliferation compared to control (−5.7%; P = .002). This was accompanied by a decrease in LoVo cell γ‐H2AX expression (−24.6%; P = .029), indicating a reduction in DNA damage. Acute exercise also increased serum IL‐6 (24.6%, P = .002). Furthermore, stimulating LoVo cells with recombinant IL‐6 reduced γ‐H2AX expression (β = −22.7%; P < .001) and cell proliferation (β = −5.3%; P < .001) in a linear dose‐dependent manner, mimicking the effect of exercise. These findings suggest that the systemic responses to acute aerobic exercise inhibit colon cancer cell proliferation in vitro, and this may be driven by IL‐6‐induced regulation of DNA damage and repair. This mechanism of action may partly underlie epidemiological associations linking regular physical activity with reduced colon cancer risk.

Acute Responses In Agonists Of Uegf To Moderate-intensity And High-intensity Interval Exercise In Mid-spectrum Ckd

Acute Responses In Agonists Of Uegf To Moderate-intensity And High-intensity Interval Exercise In Mid-spectrum Ckd

Irisin serum increasing pattern is higher at moderate-intensity continuous exercise than at moderate-intensity interval exercise in obese females

Lifestyle, unhealthy eating patterns, and low physical activity become trigger factors of obesity. Therefore, lifestyle modification with an exercise-based nonpharmacological approach is one of the strategies for combat obesity. This study aims to analyse the response of moderate-intensity interval and continuous exercise to irisin level increasing pattern on the obese female. A total of 21 obese females were enrolled in this study and given moderate-intensity interval exercise (MIIE) and moderate-intensity continuous exercise (MICE). ELISA was used to quantify the serum level of irisin in all samples. Statistical analysis was performed using one way-ANOVA and Tukey’s honestly significant difference (HSD) post hoc test. Mean irisin levels of pre-exercise at control (CON), MIIE, and MICE were 3.26±1.28l, 3.44±0.56 and 3.89±1.08 ng/ml, respectively (P=0.519). The mean irisin level of 10 min post-exercise was 2.99±0.86 ng/ml at CON, 4.82±1.01 ng/ml at MIIE, and 5.99±1.27 ng/ml at MICE (P=0.000). The mean irisin levels of 6 h post-exercise were 3.04±0.60, 4.56±0.87, and 5.73±1.02 ng/ml at CON, MIIE, and MICE, respectively (P=0.000). The mean irisin level of 24 h post-exercise was 3.04±0.91 ng/ml at CON, 4.64±0.69 ng/ml at MIIE, and 5.69±1.53 ng/ml at MICE (P=0.002). We conclude that the post-exercise serum irisin level increased in both MICE and MIIE subjects, and the post-exercise serum irisin level maintained higher in the MICE than in the MIIE in the obese female subjects.

Air pollution concentration and period of the day modulates inhalation of PM2.5 during moderate- and high-intensity interval exercise

The increase in minute ventilation during exercise led to higher inhalation of air pollution and, consequently, to exacerbation of health issues. Therefore, the intensity of exercise and the air pollution concentration of the environment could be determinant variables to poor outcomes. This study aimed to investigate the inhaled dose of particulate matter 2.5 (PM2.5) during a moderate- and high-intensity interval exercise session performed in the morning and evening at different locations of Porto Alegre City. Eighteen individuals performed a cardiopulmonary exercise test, a moderate-intensity interval exercise (MIIE), and a high-intensity interval exercise (HIIE). Heart rate was monitored to estimate minute ventilation and total ventilation of the session. The concentration of PM2.5 was measured during the morning (6–8a.m.) and evening (6–8p.m.) by fixed-site monitors placed at five points of Porto Alegre City. The PM2.5 inhalation during MIIE and HIIE performed in the morning and evening in the monitoring points was estimated. HIIE showed higher minute ventilation (VE) (p = 0.0048) and total ventilation did not differ between groups (p = 0.4648). PM2.5 concentrations were higher during the mornings (p < 0.001). Monitored point 1 had higher levels of PM2.5 in the morning and evening (p < 0.001). The inhalation of PM2.5 in the morning showed no difference in MIIE (p = 0.8172) and HIIE (p = 0.7306) groups among the points. In the evening, the inhalation of PM2.5 was higher in point 1 in MIIE and HIIE group (p < 0.001). MIIE and HIIE had higher inhalation of PM2.5 in the morning than in the evening (p < 0.001). Total ventilation of exercise is a crucial factor that contributes to the inhalation dose of air pollution.

Secretion Of PGC-1α By Modulating Physical Exercise To Protect Improving Obesity Prevalence

This study aims to analyze the response of physical exercise as a modulation of PGC-1α to protect against the increasing prevalence of obesity. This research is a true experimental design with the randomized pretest-posttest control group design using 15 obese women aged 18-22 years, Body Mass Index (BMI) 25-35 kg/m2, normal blood pressure, Resting Heart Rate (RHR) normal, VO2max 25-35 ml/kg/min and randomly divided into three groups, namely CONT (n=5, Control Without Intervention), MIIE (n=5, Moderate Intensity Interval Exercise) and MICE (n=5, Moderate Intensity Continuous Exercise). The intervention was carried out at 07.00-09.00 a.m. MIIE and MICE interventions carried out for 40-45 minutes using a treadmill. Pre-exercise blood sampling and 10 minutes post-exercise. Measurement of PGC-1α levels used the Enzyme-Linked Immunosorbent Assay (ELISA) method. Data analysis techniques used ANOVA test and LSD post hoc test with the Statistical Package for Social Science (SPSS)

Ethnic Differences In Post-prandial Glycemic Control After Acute Moderate-intensity Continuous Or High-intensity Interval Exercise

PURPOSE: To examine the effects of acute continuous moderate-intensity aerobic exercise (CME) and low-volume high-intensity interval training (LV-HIIT) on glycemic control in white Europeans (WEs) and south Asians (SAs) with impaired glycemic control. METHODS: 23 participants (WE / SA [M/F]: 13[6/7] / 10[7/3]; median (IQR): age 67 (60–68) years, BMI 30.0 (28.4–32.8) kg/m2, waist circumference 100.8 (97.6–109.1) cm, HbA1c 5.9 (5.8–6.1) %) completed three 6 h trials (control [CON], CME, LV-HIIT; randomized order). Participants rested throughout, except for 35 min of CME and 25 min of LV-HIIT (closely matched for external work produced) during corresponding trials. Both CME and LV-HIIT ended at 2 h. Standardized meals were consumed at 0 and 3 h. Plasma glucose and insulin were measured at 0, 0.5, 1, 2, 3, 3.5, 4, 5 and 6 h. Data were analysed as post-exercise time-averaged area under the curve (AUCpost), using generalized estimating equations, adjusted for pre-exercise AUC (also time-averaged), sex and age. Main effects of trial and ethnicity were assessed, with an interaction term fitted to explore if ethnicity modulated responses. Insulin resistance index (IRI) was calculated as tAUCglu x tAUCins. RESULTS: Glucose was unaffected (all p ≥ 0.28), but insulin AUCpost was reduced in both exercise trials compared to CON (main effect p < 0.001; Figure 1A). Furthermore, this effect was modulated by ethnicity (p = 0.03), with a greater effect seen in SAs. Notably, insulin AUCpost was similar in both ethnicities during exercise trials, despite being higher in SAs during CON (Figure 1A). Results were similar for IRI (Figure 1B). CONCLUSION: Despite ~30% higher post-prandial insulin responses during prolonged sitting, SAs may benefit more from acute exercise than WEs. Acknowledging that this was an acute-crossover study, these findings warrant further investigation with longer-term exercise training interventions, given the higher cardiometabolic disease risk observed in SAs.

Acute effects of moderate-intensity and high-intensity exercise on hemodynamic and autonomic reactivity to the cold pressor test in young adults with excess body weight.

To investigate the effects of a single session of moderate-intensity and high-intensity interval exercise in cardiovascular reactivity to the cold pressor test in young adults with excess body weight. Twenty-two subjects with excess body weight (23 ± 2 years; 30.0 ± 3.4 kg·m) performed three sessions: (1) moderate-intensity exercise (30-minute cycling at 50%-60% of heart rate reserve); (2) high-intensity exercise (four series of 3-minute cycling at 80%-90% of heart rate reserve, interspersed by 2-minute recovery) and (3) control (i.e. 30-minute seated). Before and 30 minutes after the interventions, subjects undertook assessments of SBP/DBP and heart rate in response to the cold pressor test (1-minute rest + 1-minute hand immersed in 4°C water). Reactivity was calculated as the absolute response of SBP, DBP and heart rate to cold pressor test and compared between interventions using a two-way analysis of variance (P < 0.05). Neither moderate-intensity exercise or high-intensity interval exercise attenuated SBP/DBP reactivity to cold pressor test compared with control. On the other hand, heart rate reactivity was reduced after moderate-intensity exercise compared with control (1.36 ± 8.35 bpm vs. 5.18 ± 9.45 bpm). Furthermore, moderate-intensity exercise reduced absolute levels of SBP/DBP from pre- to post-intervention. A single session of moderate-intensity exercise or high-intensity interval exercise did not reduce the SBP/DBP reactivity to cold pressor test. However, absolute levels of SBP/DBP were lower after moderate-intensity exercise, indicating a hypotensive effect promoted by a single session of moderate-intensity exercise in young adults with excess body weight.

The affective interval: An investigation of the peaks and valleys during high- and moderate-intensity interval exercise in regular exercisers

Evidence supports the notion that people generally feel worse during high(er) intensity exercise but experience an affective rebound immediately following cessation that often exceeds pre-exercise feeling states. Considering rest/recovery is an integral part of interval exercise, it is of interest to determine the degree of affective reactivity and recovery that may occur during interval exercise of different intensities. The purpose of the present study was to examine affective reactivity to and recovery from an acute bout of moderate-intensity (MIIE) and high-intensity interval exercise (HIIE). Participants (N = 25, 13 females, 23.3 ± 4.0 yrs, BMI = 25.7 ± 4.1 kg m−2) completed 4 sessions at the same time of day with at least 24-h between each session: a baseline session to record resting affect, a graded exercise test on a stationary bike (cycle ramp protocol 25 W·min-1) to volitional exhaustion, and then completed a high- (HIIE) and moderate-intensity interval exercise (MIIE) session where affect was recorded prior to, during, and up to 30-min post exercise. Participants reported more negative feeling states during the HIIE session compared to the MIIE session, but these states recovered similarly as early as 5-min post-exercise. In addition, while affective change (reactivity and rebounds) were relatively equal during the MIIE, declines in affect during the HIIE outweighed the affective rebounds associated with rest, resulting in a large decline in affective state from pre-exercise.

Acute high-intensity and moderate-intensity interval exercise do not change corticospinal excitability in low fit, young adults.

Previous research has demonstrated a lack of neuroplasticity induced by acute exercise in low fit individuals, but the influence of exercise intensity is unclear. In the present study, we assessed the effect of acute high-intensity (HI) or moderate-intensity (MOD) interval exercise on neuroplasticity in individuals with low fitness, as determined by a peak oxygen uptake (VO2peak) test (n = 19). Transcranial magnetic stimulation (TMS) was used to assess corticospinal excitability via area under the motor evoked potential (MEP) recruitment curve before and following training. Corticospinal excitability was unchanged after HI and MOD, suggesting no effect of acute exercise on neuroplasticity as measured via TMS in sedentary, young individuals. Repeated bouts of exercise, i.e., physical training, may be required to induce short-term changes in corticospinal excitability in previously sedentary individuals.

Renal Function Responses To Steady-state Moderate-intensity And High-intensity Interval Exercise In Mid-spectrum Chronic Kidney Disease

Renal Function Responses To Steady-state Moderate-intensity And High-intensity Interval Exercise In Mid-spectrum Chronic Kidney Disease

Effects of exercise intensity on vascular and autonomic components of the baroreflex following glucose ingestion in adolescents

PurposeTo investigate the effects of an oral glucose tolerance test (OGTT) on baroreflex sensitivity (BRS) in a sample of healthy adolescents, and how acute exercise bouts of different intensities alter the effects of the OGTT on BRS.MethodsThirteen male adolescents (14.0 ± 0.5 years) completed three conditions on separate days in a counterbalanced order: (1) high-intensity interval exercise (HIIE); (2) moderate-intensity interval exercise (MIIE); and (3) resting control (CON). At ~ 90 min following the conditions, participants performed an OGTT. Supine heart rate and blood pressure were monitored continuously at baseline, 60 min following the conditions, and 60 min following the OGTT. A cross-spectral method (LFgain) was used to determine BRS gain. Arterial compliance (AC) was assessed as the BRS vascular component. LFgain divided by AC (LFgain/AC) was used as the autonomic component.ResultsAlthough non-significant, LFgain moderately decreased post-OGTT when no exercise was performed (pre-OGTT = 24.4 ± 8.2 ms mmHg− 1; post-OGTT = 19.9 ± 5.6 ms mmHg− 1; ES = 0.64, P > 0.05). This was attributed to the decrease in LFgain/AC (pre-OGTT = 1.19 ± 0.5 ms µm− 1; post-OGTT = 0.92 ± 0.24 ms µm− 1; ES = 0.69, P > 0.05). Compared to CON (Δ = − 4.4 ± 8.7 ms mmHg− 1), there were no differences for the pre–post-OGTT delta changes in LF/gain for HIIE (Δ = − 3.5 ± 8.2 ms mmHg− 1) and MIIE (Δ = 1.3 ± 9.9 ms mmHg− 1) had no effects on BRS following the OGTT (all ES < 0.5). Similarly, compared to CON (Δ = − 0.23 ± 0.40 ms µm− 1) there were no differences for the pre–post-OGTT delta changes in LF/gain for HIIE (Δ = − 0.22 ± 0.49 ms µm− 1) and MIIE (Δ = 0.13 ± 0.36 ms µm− 1).ConclusionA moderate non-significant decrease in BRS was observed in adolescents following a glucose challenge with no apparent effects of exercise.

PO-161 Effect of different type of exercise on mitochondrial homeostasis in rats with myocardial infarction

Objective To investigate the different effect of moderate-intensity continuous training (MCT) and high-intensity interval exercise training (HIT) on ventricular remodeling and mitochondrial homeostasis after acute myocardial infarction (AMI).&#x0D; Methods The AMI rat model was achieved by ligating coronary artery. The AMI and sham operation rats were randomly divided into four groups: sham operation group (Sham), AMI control group (AMI), AMI MCT group (AMI+M), and AMI HIT group (AMI+H). Animals in the AMI+M and AMI+H groups underwent 4 weeks MCT and HIT respectively. Five weeks after AMI, hemodynamic changes, mitochondrial bioenergetics, and PINK1, Beclin1, Mfn2, Drp1, Tfam, COXⅣ, PGC-1α were detected.&#x0D; Results Comparing with AMI group, in AMI+M and AMI+H groups, Beclin1 (146.33±18.47, 143.28±16.96.vs. 123.27±13.27, P&lt;0.05), PINK1 (150.33±20.54, 152.28±18.34.vs. 125.27±17.67, P&lt;0.05), Mfn2 (122.28±18.81, 117.19±17.04.vs. 46.27±6.72, P&lt;0.01), and PGC-1α (82.15±16.58, 102.25±13.27.vs. 60.27±9.36, P&lt;0.05~0.01) expression elevated significantly, whereas ROS generation (122.28±18.81, 117.19±17.04.vs. 46.27±6.72, P&lt;0.01) and Drp1 expression (9.58±1.40, 10.18±1.37.vs. 15.85±1.61, P&lt;0.05) showed dramatic decrease. In addition, in AMI+H group, +dp/dt max (6326±325.vs. 5368±271, P&lt;0.05), -dp/dt max (-5312±246.vs. -4457±250, P&lt;0.05), mitochondrial membrane potential (85.24±11.94.vs. 71.28±8.34, P&lt;0.05), ATP synthesis activity (38.77±5.16.vs. 32.33±4.14, P&lt;0.05), Tfam (95.25±12.05.vs. 78.27±12.22, P&lt;0.05) and COXⅣ (89.25±14.06.vs. 67.27±13.71, P&lt;0.05) expression improved significantly. Comparing with AMI+M group, in AMI+H group, +dp/dt max (6326±325.vs. 5775±310, P&lt;0.05), -dp/dt max (-5312±246.vs. -4778±305, P&lt;0.05), PGC-1α (102.25±13.27.vs. 82.15±16.58 1, P&lt;0.05), Tfam (95.25±12.05.vs. 80.15±11.99, P&lt;0.05) and COXⅣ(89.25±14.06.vs. 72.15±10.89, P&lt;0.05) expression improved significantly.&#x0D; Conclusions High-intensity interval exercise training is superior to moderate-intensity continuous training for ameliorating ventricular remodeling and mitochondrial homeostasis after acute myocardial infarction.

Mechanisms of blood pressure control following acute exercise in adolescents: Effects of exercise intensity on haemodynamics and baroreflex sensitivity.

What is the central question of this study? What are the autonomic and vascular components of the baroreflex during hypotension following different exercise intensities in adolescents? What is the main finding and its importance? Hypotension after high-intensity exercise lasted 60min, whereas following moderate-intensity exercise, blood pressure was restored after 20min. Stroke volume and peripheral resistance responses were different between intensities. Post both exercise intensities, baroreflex sensitivity was lowered mainly due to the autonomic component, which returned to baseline 60min post-exercise. The different haemodynamic stimuli indicate potential differences in cardiovascular health benefits of exercise intensity in healthy adolescents. This work aimed to investigate the time course of changes in baroreflex sensitivity (BRS) and its vascular and autonomic components after different exercise intensities in adolescents. Thirteen male adolescents (age 13.9±0.5years) completed on separate days in a counterbalanced order (1) high-intensity interval exercise (HIIE): 8×1min running at 90% of maximal aerobic speed with 75s of active recovery; (2) moderate-intensity interval exercise (MIIE): 10-12 bouts of 1min running at 90% of gas exchange threshold with 75s of active recovery; and (3) resting as a control. Supine heart rate and blood pressure were monitored continuously at baseline, and 5 and 60min following the conditions. A cross-spectral method (low frequency gain; LFgain ) was used to determine BRS gain. Arterial compliance (AC) was assessed as the BRS vascular component. LFgain /AC was used as the autonomic component. LFgain decreased 5min post-exercise bouts (HIIE P<0.001; MIIE P=0.002), but returned to baseline at 60min post-exercise. AC increased at 5min post-exercise for all conditions (P=0.048), and returned to baseline at 60min post-exercise. LFgain /AC decreased 5min post-exercise bouts (HIIE P=0.001; MIIE P=0.004), but returned to baseline values at 60min post-exercise. Mean arterial pressure was lowered by both exercise intensities at 5min post-exercise, but remained decreased at 60min post-exercise following HIIE only. In conclusion, BRS decreases 5min following exercise in adolescents independent of exercise intensity and is mainly driven by a lowered autonomic response. At 60min post-exercise, the ability of BRS to regulate blood pressure is restored after MIIE but not after HIIE, indicating exercise intensity-dependent mechanisms.

Perceptual Responses to High- and Moderate-Intensity Interval Exercise in Adolescents.

Continuous high-intensity exercise is proposed to evoke unpleasant sensations as predicted by the dual-mode theory and may negatively impact on future exercise adherence. Previous studies support unpleasant sensations in affective responses during continuous high-intensity exercise, but the affect experience during high-intensity interval exercise (HIIE) involving brief bursts of high-intensity exercise separated by low-intensity activity is poorly understood in adolescents. We examined the acute affective, enjoyment, and perceived exertion responses to HIIE compared with moderate-intensity interval exercise (MIIE) in adolescents. Thirteen adolescent boys (mean ± SD: age, 14.0 ± 0.5 yr) performed two counterbalanced exercise conditions: 1) HIIE: 8 × 1-min work intervals at 90% maximal aerobic speed; and 2) MIIE: between 9 and 12 × 1-min work intervals at 90% ventilatory threshold where the number of intervals performed were distance-matched to HIIE. HIIE and MIIE work intervals were interspersed with 75 s active recovery at 4 km·h. Affect, enjoyment, and RPE were recorded before, during, and after exercise. Affect responses declined in both conditions but the fall was greater in HIIE than MIIE (P < 0.025, effect size [ES], 0.64 to 0.81). Affect remained positive at the end-work interval for both conditions (MIIE, 2.62 ± 1.50; HIIE, 1.15 ± 2.08 on feeling scale). No enjoyment differences were evident during HIIE and MIIE (P = 0.32), but HIIE elicited greater postexercise enjoyment compared with MIIE (P = 0.01, ES = 0.47). RPE was significantly higher during HIIE than MIIE across all work intervals (all P < 0.03, ES > 0.64). Despite elevated RPE, HIIE did not elicit prominent unpleasant feelings as predicted by the dual-mode theory and was associated with greater postexercise enjoyment responses than MIIE. This study demonstrates the feasibility of the application of HIIE as an alternative form of physical activity in adolescents.

Moderate-intensity interval exercise but not high-intensity interval exercise improves the spatial memory of ovariectomized rats

Physical exercise exerts beneficial effects on the spatial learning and memory. High-intensity interval exercise (HIIE) has been proposed as a time-efficient physical exercise regimen. On the other hand, there were evidences that HIIE increased oxidative stress biomarkers and reduced antioxidant capacity, which resulted in oxidative damage. The present study aimed to investigate the effects of high-intensity interval exercise and moderate-intensity interval exercise on oxidative stress biomarkers and oxidative enzymes activity in the hippocampus and the spatial memory of ovariectomized rats. A total of 16 female Sprague Dawley rats aged 12 weeks were randomly assigned into 4 groups, i.e. the sham-operated (SO), ovariectomized without exercise (O), ovariectomized with high-intensity interval exercise (HIIE), and ovariectomized with moderate-intensity interval exercise (MIIE) groups. Rats of the exercise groups (HIIE & MIIE groups) performed 6 sessions of interval exercise per week for 6 weeks. The spatial memory of rats was measured using the Morris water maze procedure. The malondialdehyde (MDA) levels and activity of catalase (Cat) as well as glutathione peroxidase (GPx) in hippocampus were determined using spectrophotometry method. The spatial learning and memory retention of the moderate-intensity interval exercise group was significantly better than that of the high-intensity interval exercise group. The GPx activity of MIIE group was higher than any other groups. The SO group had the lowest hippocampal MDA level and highest Cat activity among groups. Moderate-intensity interval exercise reduces the ovariectomy induced-oxidative stress in the hippocampus and improves spatial learning and memory retention of ovariectomized rats.

Glucose response to exercise in the post-prandial period is independent of exercise intensity.

This study investigated the acute glucose response to low-intensity, moderate-intensity, and high-intensity interval exercise compared to no-exercise in healthy insufficiently active males using a four-arm, randomized, crossover design. Ten males (age: 37.3±7.3years, BMI: 29.3±6.5kg·m-2 ) completed four 30-minute interventions at weekly intervals comprising low-intensity exercise (LIE) at ~35% V˙O2 R, moderate-intensity exercise (MIE) at ~50% V˙O2 R, high-intensity interval exercise (HIIE) at ~80% V˙O2 R, and a no-exercise control. Participants performed cycle ergometer exercise 30minutes after finishing breakfast. Glucose response was assessed using a continuous glucose monitor under free-living conditions with dietary intake replicated. A significant effect for intensity on energy expenditure was identified (P<.001) with similar energy cost in MIE (mean±SD: 869±148kJ) and HIIE (806±145 kJ), which were both greater than LIE (633±129kJ). The pattern of glucose response between the interventions over time was different (P=.02). Glucose was lower 25minutes into each of the HIIE, MIE and LIE trials respectively (mean difference±SD: -0.7±1.1; -0.9±1.1; -0.6±0.9mmol·L-1 ; P<.05) than in the no-exercise trial. Glucose response was not different between exercise intensities (P>.05). Twenty-four-hour AUC was not affected by exercise intensity (P=.75). There was a significant effect for exercise enjoyment (P=.02), with LIE (69±4) preferred less than HIIE (mean±SD: 84±14; P=.02), MIE (73±5; P=.03), and no-exercise (75±4; P=.03). Exercise at any intensity 30minutes after a meal affects glycemic regulation equally in insufficiently active males. Moderate to vigorous exercise intensities were preferred, and therefore, the exercise guidelines appear appropriate for the prevention of cardiometabolic disease.