Session Of High-intensity Interval Exercise Research Articles

QTc interval prolongation during recovery from brief high-intensity intermittent exercise in obese adults.

The risk of malignant arrhythmias is higher during extremely intense exercise and after its cessation. It is still unclear whether high-intensity interval exercise (HIE), an increasingly popular option in preventive and rehabilitative medicine, can lead to an impaired electrophysiological milieu, as revealed by QT interval prolongation on an electrocardiogram. This study investigated heart rate-corrected QT interval (QTc) dynamics during recovery from HIE in obese adults. In total, 13 obese males (age: 24.3 ± 4.6years old; body mass index: 31.6 ± 4.1 kg/m2) underwent: (1)HIE: an HIE session of four 30-s all-out cycling efforts interspersed with 4‑min recovery periods; (2)REC: arecovery session 24 h after HIE; and (3)CON: acontrol session of no treatment. The QT interval was measured before HIE, REC, and CON, and then at 30-min intervals thereafter, for up to 3 h. QTc values were obtained using Bazett, Fridericia, Framingham, Hodges, and Rautaharju correction formulas. Acute HIE led to asignificant increase in QTc for each correction (by 5-47 ms, all p < 0.05), and QTc was significantly longer during early recovery from acute exercise (HIE) compared with CON corrected with the Bazett (by 49 ms), Fridericia (by 11 ms), Hodges (by 27 ms), and Rautaharju (by 15 ms) formulas (all p < 0.05). Further, the QTc for each correction at most of the observation points in the REC trial was significantly longer (by 5-10 ms, all p < 0.05) than the corresponding value of the CON. In conclusion, in obese adults, the risk of QTc prolongation increased after brief HIE, and the risk may be sustained for more than 24 h.

Effect of Low-Volume High-Intensity Interval Exercise and Continuous Exercise on Delayed-Onset Muscle Soreness in Untrained Healthy Males.

Farias Junior, LF, Browne, RAV, Frazão, DT, Dantas, TCB, Silva, PHM, Freitas, RPA, Aoki, MS, and Costa, EC. Effect of low-volume high-intensity interval exercise and continuous exercise on delayed-onset muscle soreness in untrained healthy males. J Strength Cond Res 33(3): 774-782, 2019-The aim of this study was to compare the effect of a single session of a low-volume high-intensity interval exercise (HIIE) and a continuous exercise (CE) on the magnitude of delayed-onset muscle soreness (DOMS) in untrained healthy males. Fifteen participants (25.1 ± 4.4 years) completed 2 experimental sessions in a randomized order: (a) low-volume HIIE: 10 × 60 seconds at 90% of maximal velocity (MV) interspersed with 60 seconds of active recovery at 30% of MV and (b) CE: 20 minutes at 60% of MV. Pressure-pain threshold (PPT), pressure-pain tolerance (PPTol), and perceived pain intensity (PPI) were assessed in the rectus femoris, biceps femoris, and gastrocnemius before and 24 hours after exercise. There was a decrease of PPT in the rectus femoris (-0.5 kg·cm) and PPTol in the gastrocnemius (-1.4 kg·cm) and an increase of PPI in the rectus femoris (14.4 mm) and in the biceps femoris (11.7 mm) 24 hours after the low-volume HIIE session (p ≤ 0.05). There was a decrease of PPT (rectus femoris: -0.8 kg·cm; biceps femoris: -0.5 kg·cm; gastrocnemius: -0.9 kg·cm) and PPTol (rectus femoris: -1.9 kg·cm; biceps femoris: -2.7 kg·cm; gastrocnemius: -1.6 kg·cm) and an increase of PPI (rectus femoris: 8.1 mm; biceps femoris: 10.3 mm; gastrocnemius: 17.5 mm) in all muscles 24 hours after the CE session (p ≤ 0.05). No difference was observed between HIIE and CE sessions in any DOMS-related parameter (p > 0.05). In conclusion, a single session of low-volume HIIE and CE elicited a similar mild DOMS 24 hours after exercise in untrained healthy males.

The Effects of High-Intensity Interval Exercise and Hypoxia on Cognition in Sedentary Young Adults.

Background and Objectives: Limited research has evaluated the effects of acute exercise on cognition under different conditions of inspired oxygenation. Thus, the purpose of this study was to examine the effects of high-intensity interval exercise (HIE) under normoxia (inspired fraction of oxygen (FIO2): 0.209) and moderate hypoxia (FIO2: 0.154) on cognitive function. Design: A single-blinded cross-over design was used to observe the main effects of exercise and oxygen level, and interaction effects on cognitive task performance. Methods: Twenty inactive adults (10 males and 10 females, 19–27 years old) performed a cognitive task (i.e., the Go/No-Go task) before and immediately after an acute bout of HIE under normoxic and hypoxic conditions. The HIE comprised 10 repetitions of 6 s high-intensity cycling against 7.5% body weight interspersed with 30 s passive recovery. Heart rate, peripheral oxygen saturation (SpO2) and rating of perceived exertion were monitored. Results: The acute bout of HIE did not affect the reaction time (p = 0.204, η2 = 0.083) but the accuracy rate decreased significantly after HIE under both normoxic and hypoxic conditions (p = 0.001, η2 = 0.467). Moreover, moderate hypoxia had no influence either on reaction time (p = 0.782, η2 = 0.004) or response accuracy (p = 0.972, η2 < 0.001). Conclusions: These results indicate that an acute session of HIE may impair response accuracy immediately post-HIE, without sacrificing reaction time. Meanwhile moderate hypoxia was found to have no adverse effect on cognitive function in inactive young adults, at least in the present study.

Cardiometabolic Response to a Single High-intensity Interval Exercise Session Versus Breaking up Sedentary Time with Fragmented High-intensity Interval Exercise.

This study compared the effects of interrupting prolonged sedentary time with high-intensity physical activity (SED-ACT), a volume- and duration-matched high-intensity interval exercise session followed by prolonged sedentary time (HIIE), and prolonged uninterrupted sedentary time (SED) on postprandial glucose, insulin and triglyceride concentrations. Twelve sedentary and inactive but otherwise healthy adults completed 3, 6.5 h conditions in an incomplete counterbalanced order. During SED, participants sat continuously. For HIIE, participants completed 10×60 s cycling bouts at 90% maximum oxygen update (V̇O2max) with 1 min active recovery between bouts. In SED-ACT, 60 s cycling bouts at 90% V̇O2max were completed every 30 min (10 times in total) with 30 s of active recovery immediately before and after. Standardised meals were consumed at 0 h and 3 h and capillary blood samples were collected fasted and every 30 min. Compared with SED, postprandial glucose incremental area under the curve (iAUC) was significantly lower in SED-ACT by 1.91 mmol/L∙6.5 h (p=0.022) and triglyceride iAUC was significantly lower in HIIE by 1.02 mmol/L∙6.5 h (p=0.030). Interrupting sedentary time with high-intensity physical activity can lower postprandial glucose concentrations, whereas a HIIE session can lower postprandial triglyceride concentrations.

Late Neutrophil Priming Following a Single Session of High-intensity Interval Exercise.

This study evaluated the effect of an acute high-intensity interval exercise (HIIE) session on the function of human neutrophils. Twelve sedentary men performed a HIIE session (8 bouts of 60 s at 90% of peak power, intercalated with 75 s of active recovery at 30 W). Neutrophils were collected before, 30 min and 24 h after the exercise session for the evaluation of phagocytic capacity, expression of phagocytic receptors, reactive oxygen species generation, and redox status. 24 h after the HIIE session, an increase was observed in both neutrophil phagocytic capacity and yeast-induced generation of reactive oxygen species, which indicates neutrophil priming in response to an acute HIIE session. Neutrophils also presented an increase in superoxide dismutase activity 24 h after the exercise. Improvement in neutrophil function was accompanied by increased serum levels of IL-8 and increased concentration of plasma lactate dehydrogenase. Our findings show a late activating effect of one HIIE session on neutrophils. We propose that priming of neutrophils by HIIE may play a role in skeletal muscle inflammation after exercise.

Effects of High Carbohydrate vs. High Protein Pre-exercise Feedings on Psychophysiological Responses to High Intensity Interval Exercise in Overweight Perimenopausal Women.

Objective: To investigate (a) the acute effect of a bout of high intensity interval exercise (HIIE) on mood, cognitive function, and blood pressure in overweight perimenopausal women and (b) to compare the effects of high carbohydrate vs. high protein pre-HIIE feedings on exercise capacity, mood and cognitive function in this population.Methods: Twelve, overweight, perimenopausal women (age; 45.5 ± 2.3 years, body fat; 32.2 ± 2.1%) completed a bout of HIIE under 3 pre-exercise feedings (HCHO: high-carbohydrate-low-protein; LCHP: low-carbohydrate-high-protein; control: fasted) in a randomized crossover design. HIIE consisted of 4 intervals of 4 min walking at 85–90% of maximum heart rate and 3 min recovery. Before and after HIIE, the shortened version of the profile of mood state questionnaire, the exercise—induced feeling inventory questionnaire and three cognitive function tests (Stroop test, Shift Stroop test, n-back test) were administered. Blood pressure was measured pre- and post-exercise. Following HIIE a performance test to volitional fatigue was conducted.Results: A single bout of HIIE resulted in significant reductions in blood pressure and improvements in cognitive capacity (p < 0.05). Both the HCHO and LCHP feedings led to significantly longer exercise performance compared to CON (422 ± 71 s and 340 ± 46 vs. 240 ± 32 s, respectively, p < 0.01), with a 1.22-fold greater increase in performance time in HCHO compared to LCHP, although not statistically significant (p > 0.05). Only the HCHO trial improved total mood disturbance and positive engagement 1 h-post-exercise compared to CON (p < 0.05). HCHO and LCHP improved physical exhaustion and revitalization feelings post-exercise vs. CON (p < 0.01).Conclusions: A single HIIE session improves cognitive function and blood pressure in overweight perimenopausal women. High-carbohydrate pre-HIIE feedings can result in greater enhancements in mood and positive engagement to exercise and may improve exercise performance compared to a high-protein meal.

No effect of meal intake on physiological or perceptual responses to self-selected high intensity interval exercise (HIIE).

The present study examined the effect of meal intake on physiological and psychological indices during self-selected high intensity interval exercise (HIIE). Seventeen active men and women (age = 26.4 ± 5.8 yr) completed ramp cycle ergometry to determine maximal oxygen uptake and peak power output. On two subsequent days, they performed a session of self-selected HIIE consisting of ten 1 min bouts separated by 1 min recovery in the fed or fasted state, whose order was randomized. Meal intake consisted of a banana and a Zone™ bar containing 315 kcal, which were ingested 2 h pre-exercise, and the fasted state required no food for > 12 h pre-exercise. Participants ingested an identical meal the evening before each session. Heart rate (HR), oxygen uptake (VO2), blood glucose and blood lactate concentration, rating of perceived exertion (RPE), affect, and enjoyment were measured during exercise. Irrespective of fed state, both bouts elicited intensities equal to 94% HRmax which represents HIIE. Our results showed no difference in HR (174.0 ± 13.5 vs. 173.2 ± 12.9 b/min in fed and fasted state, p = 0.17), VO2 (2.43 ± 0.54 vs. 2.40 ± 0.52 L/min in fed and fasted state, p = 0.14), RPE (p = 0.44), affect (p = 0.79), or enjoyment (103 ± 14 vs. 101 ± 13, p = 0.77) between the fed and fasted state. Despite its high reliance on carbohydrate, performance and perception of low-volume HIIE are not altered by ingestion of a meal before exercise.

Prolonged Sitting Interrupted by 6-Min of High-Intensity Exercise: Circulatory, Metabolic, Hormonal, Thermal, Cognitive, and Perceptual Responses.

The aim was to examine certain aspects of circulatory, metabolic, hormonal, thermoregulatory, cognitive, and perceptual responses while sitting following a brief session of high-intensity interval exercise. Twelve students (five men; age, 22 ± 2 years) performed two trials involving either simply sitting for 180 min (SIT) or sitting for this same period with a 6-min session of high-intensity exercise after 60 min (SIT+HIIT). At T0 (after 30 min of resting), T1 (after a 20-min breakfast), T2 (after sitting for 1 h), T3 (immediately after the HIIT), T4, T5, T6, and T7 (30, 60, 90, and 120 min after the HIIT), circulatory, metabolic, hormonal, thermoregulatory, cognitive, and perceptual responses were assessed. The blood lactate concentration (at T3–T5), heart rate (at T3–T6), oxygen uptake (at T3–T7), respiratory exchange ratio, and sensations of heat (T3–T5), sweating (T3, T4) and odor (T3), as well as perception of vigor (T3–T6), were higher and the respiratory exchange ratio (T4–T7) and mean body and skin temperatures (T3) lower in the SIT+HIIT than the SIT trial. Levels of blood glucose and salivary cortisol, cerebral oxygenation, and feelings of anxiety/depression, fatigue or hostility, as well as the variables of cognitive function assessed by the Stroop test did not differ between SIT and SIT+HIIT. In conclusion, interruption of prolonged sitting with a 6-min session of HIIT induced more pronounced circulatory and metabolic responses and improved certain aspects of perception, without affecting selected hormonal, thermoregulatory or cognitive functions.

Physiological responses to hypoxic constant-load and high-intensity interval exercise sessions in healthy subjects.

The aim of this study was to assess the acute cardiorespiratory as well as muscle and cerebral tissue oxygenation responses to submaximal constant-load (CL) and high-intensity interval (HII) cycling exercise performed in normoxia and in hypoxia at similar intensity, reproducing whole-body endurance exercise training sessions as performed in sedentary and clinical populations. Healthy subjects performed two CL (30min, 75% of maximal heart rate, n = 12) and two HII (15 times 1-min high-intensity exercise-1-min passive recovery, n = 12) cycling exercise sessions in normoxia and in hypoxia [mean arterial oxygen saturation 76 ± 1% (clamped) during CL and 77 ± 5% (inspiratory oxygen fraction 0.135) during HII]. Cardiorespiratory and near-infrared spectroscopy parameters as well as the rate of perceived exertion were continuously recorded. Power output was 21 ± 11% and 15% (according to protocol design) lower in hypoxia compared to normoxia during CL and HII exercise sessions, respectively. Heart rate did not differ between normoxic and hypoxic exercise sessions, while minute ventilation was higher in hypoxia during HII exercise only (+ 13 ± 29%, p < 0.05). Quadriceps tissue saturation index did not differ significantly between normoxia and hypoxia (CL 60 ± 8% versus 59 ± 5%; HII 59 ± 10% versus 56 ± 9%; p > 0.05), while prefrontal cortex deoxygenation was significantly greater in hypoxia during both CL (66 ± 4% versus 56 ± 6%) and HII (58 ± 5% versus 55 ± 5%; p < 0.05) sessions. The rate of perceived exertion did not differ between normoxic and hypoxic CL (2.4 ± 1.7 versus 2.9 ± 1.8) and HII (6.9 ± 1.4 versus 7.5 ± 0.8) sessions (p > 0.05). This study indicates that at identical heart rate, reducing arterial oxygen saturation near 75% does not accentuate muscle deoxygenation during both CL and HII exercise sessions compared to normoxia. Hence, within these conditions, larger muscle hypoxic stress should not be expected.

PL - 030 The effects of ACE gene polymorphisms on ACE content before and after High-Intensity Interval Exercise

Objective Angiotensin Converting Enzyme (ACE) is expressed in human skeletal muscle. The ACE I/D polymorphism (rs4341) has been associated with athletic performance in some studies. Studies suggested that the ACE I/D gene polymorphism is associated with ACE enzyme content in serum, however, the effect of ACE I/D on ACE protein content in human skeletal muscle in unclear. Angiotensin-converting enzyme 2 (ACE2) is a new component of the renin-angiotensin system (RAS), which is counter-regulatory to the ACE enzyme. The polymorphisms in the ACE2 gene (rs1978124 and rs2285666) have been reported to be associated with hypertension, however, their effects on ACE content in the blood and in skeletal muscle have yet to be explored. Utilising the Gene SMART cohort (n=81), we investigated whether the ACE I/D gene polymorphism (rs4341) and two ACE2 gene polymorphisms (rs1978124 and rs2285666) were associated with ACE enzyme content in the blood and skeletal muscle at baseline, and following a single session of High-Intensity Interval Exercise (HIIE).&#x0D; Methods ACE and ACE2 gene polymorphisms were determined using the TaqMan SNP assay (Applied Biosystems, Foster City, California, United States) by Mastercycler® ep realplex2 (Eppendorf, Hamburg, Germany), and QuantStudio™ 7 Flex Real-Time PCR System (Applied Biosystems, Foster City, California, United States). For quantitation of ACE content in the plasma, Abcam Human ELISA Kit (ab119577 –ACE (CD143)) was used (Abcam, Cambridge, United Kingdom). Western blots were used to measure ACE content in skeletal muscle. We used robust linear models adjusted for age to test the effect of the ACE I/D polymorphism on outcomes at baseline, using the MASS package in the R statistical software. p-values were adjusted for multiple comparisons using the Benjamini and Hochberg method, and all reported p-values are adjusted p-values. An adjusted p value &lt; 0.005 was considered significant.&#x0D; Results We found that the ACE I/D gene polymorphism was associated with ACE content in the blood (p&lt;0.005) at baseline, but not the ACE protein content in skeletal muscle at baseline. The ACE2 polymorphisms (rs1978124 and rs2285666) were not associated with ACE enzyme content in the blood or in skeletal muscle at baseline. A single session of HIIE tended (0.005 &lt; p &lt; 0.05) to increase blood ACE content immediately post exercise, while skeletal muscle ACE protein content was lower 3 hours post a single session of HIIE (p&lt;0.005). However, those changes were not related to ACE I/D or ACE2 polymorphisms.&#x0D; Conclusions The ACE I/D gene polymorphism influences ACE enzyme content in the blood but not the ACE protein content of human skeletal muscle. ACE I/D gene polymorphism does not influence the changes of ACE content after a single session of HIIE. ACE2 gene polymorphisms seem to have no effect on ACE content in the blood and skeletal muscle, before or after a session of HIIE.

ACE I/D gene variant predicts ACE enzyme content in blood but not the ACE, UCP2, and UCP3 protein content in human skeletal muscle in the Gene SMART study.

Angiotensin-converting enzyme (ACE) is expressed in human skeletal muscle. The ACE I/D polymorphism has been associated with athletic performance in some studies. Studies have suggested that the ACE I/D gene variant is associated with ACE enzyme content in serum, and there is an interaction between ACE and uncoupling proteins 2 and 3 (UCP2 and UCP3). However, no studies have explored the effect of ACE I/D on ACE, UCP2, and UCP3 protein content in human skeletal muscle. Utilizing the Gene SMART cohort ( n = 81), we investigated whether the ACE I/D gene variant is associated with ACE enzyme content in blood and ACE, UCP2, and UCP3 protein content in skeletal muscle at baseline and following a session of high-intensity interval exercise (HIIE). Using a stringent and robust statistical analyses, we found that the ACE I/D gene variant was associated with ACE enzyme content in blood ( P < 0.005) at baseline but not the ACE, UCP2, and UCP3 protein content in muscle at baseline. A single session of HIIE tended (0.005 < P < 0.05) to increase blood ACE content immediately postexercise, whereas muscle ACE protein content was lower 3 h after a single session of HIIE ( P < 0.005). Muscle UCP3 protein content decreased immediately after a single session of HIIE ( P < 0.005) and remained low 3 h postexercise. However, those changes in the muscle were not genotype dependent. In conclusion, The ACE I/D gene variant predicts ACE enzyme content in blood but not the ACE, UCP2, and UCP3 protein content of human skeletal muscle. NEW & NOTEWORTHY This paper describes the association between ACE I/D gene variant and ACE protein content in blood and ACE, UCP2, and UCP3 protein content in skeletal muscle at baseline and after exercise in a large cohort of healthy males. Our data suggest that ACE I/D is a strong predictor of blood ACE content but not muscle ACE content.

Appetite, energy intake and food reward responses to an acute High Intensity Interval Exercise in adolescents with obesity

BackgroundHigh Intensity Interval Exercise (HIIE) is currently advocated for its beneficial effect on body composition and cardio-metabolic health in children and adolescents with obesity; however its impact on appetite control and food intake remains unknown. The aim of the present study was to examine the effect of a single HIIE session on subsequent energy intake, appetite feelings and food reward in adolescents with obesity. MethodsUsing a randomized cross-over design, ad libitum energy intake, subjective appetite, and food reward were examined in 33 adolescents with obesity (13.0 (±0.9) years) following an acute high-intensity interval exercise (HIIE) versus a rest condition (CON). Absolute and relative energy intakes were measured from an ad libitum lunch meal 30 min after exercise or rest. Food reward was assessed using the Leeds Food Preference Questionnaire before and after the test meal. Appetite feelings were assessed using visual analogue scales at regular intervals throughout the day. ResultsAd libitum food intake was significantly reduced after HIIE (lunch meal: −7 (±23.7)%; p = .014 and whole day: −4 (±14.7)%; p = .044), despite unchanged appetite feelings. HIIE was also found to decrease ad libitum meal food reward in adolescents with obesity: fat relative preference (from 3.3 (±9.5) to 0.1 (±8.0); p = .03), sweet taste relative preference (from −0.8 (±13.9) to −5.0 (±11.8); p = .02) and fat implicit wanting (from 22.3 (±55.7) to −13.2 (±58.5); p = .01) were significantly decreased in response to the ad libitum meal on HIIE. When considering the degree of obesity, it appears that the adolescents with higher BMI and higher fat mass percentage showed greater food intake reductions in response to HIIE (−21 (±15)% for the third BMI tertile versus + 8 (±30)% for the first BMI tertile p = .004; −15 (±21)% for the third fat mass tertile versus + 8 (±28)% for the first fat mass tertile p = .017). ConclusionA single HIIE session resulted in reduced subsequent energy intake and food reward in adolescents with obesity. Our results also seem to indicate that these nutritional responses depend on the adolescents' degree of obesity with a greater anorexigenic effect observed with higher obesity.

Age-related changes in physical and perceptual markers of recovery following high-intensity interval cycle exercise

ABSTRACTBackground: The purpose of this study was to compare physical performance, perceptual and haematological markers of recovery in well-trained masters and young cyclists across 48 h following a bout of repeated high-intensity interval exercise.Methods: Nine masters (mean ± SD; age = 55.6 ± 5.0 years) and eight young (age = 25.9 ± 3.0 years) cyclists performed a high-intensity interval exercise session consisting of 6 × 30 s intervals at 175% peak power output with 4.5 min rest between efforts. Maximal voluntary contraction (MVC), 10 s sprint (10SST), 30-min time trial (30TT) performance, creatine kinase concentration (CK) and perceptual measures of motivation, total recovery, fatigue and muscle soreness were collected at baseline and at standardised time points across the 48 h recovery period.Results: No significant group-time interactions were observed for performance of MVC, 10SST, 30TT and CK (P > 0.05). A significant reduction in 10SST peak power was found in both masters (P = 0.002) and young (P = 0.003) cyclists at 1 h post exercise, however, both groups physically recovered at similar rates. Neither group showed significant (P > 0.05) or practically meaningful increases in CK (%∆ < 10%). A significant age-related difference was found for perceptual fatigue (P = 0.01) and analysis of effect size (ES) showed that perceptual recovery was delayed with masters cyclists reporting lower motivation (ES ±90%CI = 0.69 ± 0.77, moderate), greater fatigue (ES = 0.75 ± 0.93, moderate) and muscle soreness (ES = 0.61 ± 0.70, moderate) after 48 h of recovery.Conclusion: The delay in perceived recovery may have negative effects on long-term participation to systematic training.

Effects of High-Intensity Interval and Moderate-Intensity Continuous Exercise on Inflammatory, Leptin, IgA, and Lipid Peroxidation Responses in Obese Males.

Purpose: To compare the effects of a single high-intensity interval exercise session (HIIE) with a moderate-intensity continuous exercise session (MICE) on the inflammatory profile, IgA levels, and lipid peroxidation in sedentary obese males.Methods: Ten sedentary obese men (age 28.5 ± 2.7 years; BMI 35.9 ± 4.9 kg/m2; body fat 40.6 ± 2.0%) performed three experimental sessions, on separate days with 1 week wash-out period between interventions, according to a randomized order: (1) HIIE: 10 × 60 s at 90% of the HRmax alternated by 60 s of active recovery; (2) MICE: 20 min at 70% of the HRmax; (3) Rest—control. Blood and saliva samples were collected before, immediately after and 60 min after the end of each session in order to analyse serum levels of cytokines, IgA, and lipoperoxidation markers.Results: Leptin levels decreased immediately after HIIE (P = 0.033) and was different from the MICE (P = 0.025). IFN-γ levels were reduced immediately after (P = 0.032) and 60 min after HIIE (P = 0.003) compared to baseline, and it also increased IL-4 levels immediately after exercise (P = 0.007) compared to resting values. MICE promoted an increase in IFN-γ levels immediately after exercise (P = 0.025) and 60 min after exercise (P = 0.004) in relation to baseline. Both exercise conditions increased IL-6 levels up to 60 min after exercise (P < 0.05). The IFN-γ/IL-4 ratio decreased immediately after (P = 0.002) and 60 min after HIIE (P = 0.005) in relation to pre-exercise. No changes were found for IgA-S and TBARS for any of the conditions.Conclusion: A single HIIE session is able to decrease IFN-γ/IL-4 ratio, indicating an anti-inflammatory response, without alterations in the function of the mucosal immune system and lipoperoxidation. On the other hand, a brief session of MICE induced changes in the pattern of cytokines associated with increased cellular immune function.

Effects of ovariectomy and exercise training intensity on energy substrate and hepatic lipid metabolism, and spontaneous physical activity in mice

BackgroundMenopause is associated with fatty liver, glucose dysregulation, increased body fat, and impaired bone quality. Previously, it was demonstrated that single sessions of high-intensity interval exercise (HIIE) are more effective than distance- and duration-matched continuous exercise (CE) on altering hepatic triglyceride (TG) metabolism and very-low density lipoprotein-TG (VLDL-TG) secretion. MethodsSix weeks training using these modalities was examined for effects on hepatic TG metabolism/secretion, glucose tolerance, body composition, and bone mineral density (BMD) in ovariectomized (OVX) and sham-operated (SHAM) mice. OVX and SHAM were assigned to distance- and duration-matched CE and HIIE, or sedentary control. ResultsEnergy expenditure during exercise was confirmed to be identical between CE and HIIE and both similarly reduced post-exercise absolute carbohydrate oxidation and spontaneous physical activity (SPA). OVX vs. SHAM displayed impaired glucose tolerance and greater body fat despite lower hepatic TG, and these outcomes were not affected by training. Only HIIE increased hepatic AMPK in OVX and SHAM, but neither training type impacted VLDL-TG secretion. As expected, BMD was lower in OVX, and training did not affect long bones. ConclusionsThe results reveal intensity-dependent effects on hepatic AMPK expression and general exercise effects on subsequent SPA and substrate oxidation that is independent of estrogen status. These findings support the notion that HIIE can impact aspects of liver physiology in females while the effects of exercise on whole body substrate selection appear to be independent of training intensity. However, neither exercise approach mitigated the impairment in glucose tolerance and elevated body fat occurring in OVX mice.

Effects of a single session of high-intensity interval exercise and moderate-intensity continuous exercise on biochemical cardiovascular risk factors in obese males

Few have analyzed the effects of different intensities of acute physical exercise on biochemical parameters of cardiovascular disease. To examine the acute effects of high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) on biochemical cardiovascular markers in obese male adults. Twelve sedentary obese male subjects (28.4 ± 2.6 years old, BMI 35.5 ± 4.5 kg/m2, 39.8 ± 2.2% body fat) took part in this randomized, cross-over clinical trial. Three experimental sessions, at 7-day intervals, in random order, were carried out: (1) HIIE: 10 × 60 s at ~ 90% of maximal peak velocity, interspersed by 60 s of active recovery, (2) MICE: 20 min at ~ 70% of maximum heart rate, and (3) control session. A standardized breakfast was offered before the exercise sessions. Biochemical markers of cardiovascular risk (glycemia, total cholesterol and fractions, triglycerides, hepatic enzymes and nitrogen scores) were assessed pre-exercise, immediately post-exercise, and 60 min post-exercise. In general, no significant interaction was observed, with the exception of creatinine, that had a statistically significant two-way interaction between time and condition, F(4,40) = 5.053, p < 0.05. There was a statistically significant two-way effect in time, F(2,22) = 5.906, p < 0.05 for AST, and a statistically significant two-way effect in treatment, F(2,22) = 13.477, p < 0.05 for glucose. In this context, HIIE seems to be a safe alternative to MICE for the prevention and management of obesity, as well as the disorders observed in this population.

A Single Session of Low-Volume High-Intensity Interval Exercise Reduces Ambulatory Blood Pressure in Normotensive Men.

Dantas, TCB, Farias Junior, LF, Frazão, DT, Silva, PHM, Sousa Junior, AE, Costa, IBB, Ritti-Dias, RM, Forjaz, CLM, Duhamel, TA, and Costa, EC. A single session of low-volume high-intensity interval exercise reduces ambulatory blood pressure in normotensive men. J Strength Cond Res 31(8): 2263-2269, 2017-The magnitude and duration of postexercise hypotension (PEH) may provide valuable information on the efficacy of an exercise approach to blood pressure (BP) control. We investigated the acute effect of a time-efficient high-intensity interval exercise (HIIE) on ambulatory BP. Twenty-one normotensive men (23.6 ± 3.6 years) completed 2 experimental sessions in a randomized order: (a) control (no exercise) and (b) low-volume HIIE: 10 × 1 minute at 100% of maximal treadmill velocity interspersed with 1 minute of recovery. After each experimental session, an ambulatory BP monitoring was initiated. Paired sample t-test was used to compare BP averages for awake, asleep, and 20-hour periods between the control and the low-volume HIIE sessions. A 2-way repeated measures analysis of variance was used to analyze hourly BP after both experimental sessions. Blood pressure averages during the awake (systolic: 118 ± 6 vs. 122 ± 6 mm Hg; diastolic: 65 ± 7 vs. 67 ± 7 mm Hg) and 20-hour (systolic: 115 ± 7 vs. 118 ± 6 mm Hg; diastolic: 62 ± 7 vs. 64 ± 7 mm Hg) periods were lower after the low-volume HIIE compared with the control (p ≤ 0.05). Systolic and diastolic PEH presented medium (Cohen's d = 0.50-0.67) and small (Cohen's d = 0.29) effect sizes, respectively. Systolic PEH occurred in a greater magnitude during the first 5 hours (3-5 mm Hg). No changes were found in asleep BP (p > 0.05). In conclusion, a single session of low-volume HIIE reduced ambulatory BP in normotensive men. The PEH occurred mainly in systolic BP during the first 5 hours postexercise.

Ratings of Perceived Exertion and Self-reported Mood State in Response to High Intensity Interval Training. A Crossover Study on the Effect of Chronotype.

The aim of this study was to investigate the influence of chronotype on mood state and ratings of perceived exertion (RPE) before and in response to acute high intensity interval exercise (HIIE) performed at different times of the day. Based on the morningness–eveningness questionnaire, 12 morning-types (M-types; N = 12; age 21 ± 2 years; height 179 ± 5 cm; body mass 74 ± 12 kg) and 11 evening-types (E-types; N = 11; age 21 ± 2 years; height 181 ± 11 cm; body mass 76 ± 11 kg) were enrolled in a randomized crossover study. All subjects underwent measurements of Profile of Mood States (POMS), before (PRE), after 12 (POST12) and 24 h (POST24) the completion of both morning (08.00 am) and evening (08.00 p.m.) training. Additionally, Global Mood Disturbance and Energy Index (EI) were calculated. RPE was obtained PRE and 30 min POST HIIE. Two-way ANOVA with Tukey’s multiple comparisons test of POMS parameters during morning training showed significant differences in fatigue, vigor and EI at PRE and POST24 between M-types and E-types. In addition, significant chronotype differences were found only in POST12 after the evening HIIE for fatigue, vigor and EI. For what concerns Borg perceived exertion, comparing morning versus evening values in PRE condition, a higher RPE was observed in relation to evening training for M-types (P = 0.0107) while E-types showed higher RPE values in the morning (P = 0.008). Finally, intragroup differences showed that E-types had a higher RPE respect to M-types before (P = 0.002) and after 30 min (P = 0.042) the morning session of HIIE. No significant changes during the evening training session were found. In conclusion, chronotype seems to significantly influence fatigue values, perceived exertions and vigor in relation to HIIE performed at different times of the day. Specifically, E-types will meet more of a burden when undertaking a physical task early in the day. Practical results suggest that performing a HIIE at those times of day that do not correspond to subjects’ circadian preference can lead to increased mood disturbances and perceived exertion. Therefore, an athlete’s chronotype should be taken into account when scheduling HIIE.Trial registration:ACTRN12617000432314, registered 24 March 2017, “retrospectively registered”.Web address of trial:https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=371862&showOriginal=true&isReview=true

Exercise-intensity dependent alterations in plasma redox status do not reflect skeletal muscle redox-sensitive protein signaling

ObjectivesRedox homeostasis and redox-sensitive protein signaling play a role in exercise-induced adaptation. The effects of sprint-interval exercise (SIE), high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CMIE), on post-exercise plasma redox status are unclear. Furthermore, whether post-exercise plasma redox status reflects skeletal muscle redox-sensitive protein signaling is unknown. DesignIn a randomized crossover design, eight healthy adults performed a cycling session of HIIE (5×4min at 75% Wmax), SIE (4×30s Wingate’s), and CMIE work-matched to HIIE (30min at 50% of Wmax). MethodsPlasma hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) activity, and catalase activity were measured immediately post, 1h, 2h and 3h post-exercise. Plasma redox status biomarkers were correlated with phosphorylation of skeletal muscle p38-MAPK, JNK, NF-κB, and IκBα protein content immediately and 3h post-exercise. ResultsPlasma catalase activity was greater with SIE (56.6±3.8Uml−1) compared to CMIE (42.7±3.2, p<0.01) and HIIE (49.0±5.5, p=0.07). Peak plasma H2O2 was significantly (p<0.05) greater after SIE (4.6±0.6nmol/ml) and HIIE (4.1±0.4) compared to CMIE (3.3±0.5). Post-exercise plasma TBARS and SOD activity significantly (p<0.05) decreased irrespective of exercise protocol. A significant positive correlation was detected between plasma catalase activity and skeletal muscle p38-MAPK phosphorylation 3h post-exercise (r=0.40, p=0.04). No other correlations were detected (all p>0.05). ConclusionsLow-volume SIE elicited greater post-exercise plasma catalase activity compared to HIIE and CMIE, and greater H2O2 compared to CMIE. Plasma redox status did not, however, adequately reflect skeletal muscle redox-sensitive protein signaling.

Salivary cortisol concentration after high-intensity interval exercise: Time of day and chronotype effect

ABSTRACTDue to personal and working necessities, the time for exercise is often short, and scheduled early in the morning or late in the afternoon. Cortisol plays a central role in the physiological and behavioral response to a physical challenge and can be considered as an index of exercise stress. Therefore, the aim of this study was to evaluate the influence of the circadian phenotype classification on salivary cortisol concentration in relation to an acute session of high-intensity interval exercise (HIIE) performed at different times of the day. Based on the morningness–eveningness questionnaire, 12 M-types (N = 12; age 21 ± 2 years; height 179 ± 5 cm; body mass 74 ± 12 kg, weekly training volume 8 ± 1 hours) and 11 E-types (N = 11; age 21 ± 2 years; height 181 ± 11 cm; body mass 76 ± 11 kg, weekly training volume 7 ± 2 hours) were enrolled in a randomized crossover study. All subjects underwent measurements of salivary cortisol secretion before (PRE), immediately after (POST), and 15 min (+15 min), 30 min (+30 min), 45 min (+45 min) and 60 min (+60 min) after the completion of both morning (08.00 am) and evening (08.00 p.m.) high-intensity interval exercise. Two-way analysis of variance with Tuckey’s multiple comparisons test showed significant increments over PRE-cortisol concentrations in POSTcondition both in the morning (4.88 ± 1.19 ng · mL−1 vs 6.60 ± 1.86 ng · mL−1, +26.1%, P < 0.0001, d > 0.8) and in the evening (1.56 ± 0.48 ng · mL−1 vs 2.34 ± 0.37, +33.4%, P = 0.034, d > 0.6) exercise in all the 23 subject that performed the morning and the evening HIIE. In addition, during morning exercise, significant differences in cortisol concentration between M-types and E-types at POST (5.49 ± 0.98 ng · mL−1 versus 8.44 ± 1.08 ng · mL−1, +35%, P < 0.0001, d > 0.8), +15 min (4.52 ± 0.42 ng · mL−1 versus 6.61 ± 0.62 ng · mL−1, +31.6%, P < 0.0001, d > 0.8), +30 min (4.10 ± 1.44 ng · mL−1 versus 6.21 ± 1.60 ng · mL−1, +34.0%, P < 0.0001, d = 0.7), + 45 min (3.78 ± 0.55 ng · mL−1 versus 5.80 ± 0.72 ng · mL−1, +34.9%, P < 0.0001, d = 0.7), and + 60 min condition(3.53 ± 0.45 ng · mL−1 versus 5.78 ± 1.13 ng · mL−1, 38.9%, P = 0.0008, d = 0.7) were noted. No statistical significant differences between M-types and E-types during evening HIIE on post-exercise cortisol concentration were detected. E-types showed a higher morning peak of salivary cortisol respect to M-types when performing a HIIE early in the morning and produced higher salivary cortisol concentrations after the cessation of the exercise. Practical applications suggest that it is increasingly important for the exercise professionals to identify the compatibility between time of day for exercising and chronotype to find the individual’s favorable circadian time to perform a HIIE.