Single Session Of High-intensity Interval Training Research Articles

High-intensity interval training using electrical stimulation ameliorates muscle fatigue in chronic kidney disease-related cachexia by restoring mitochondrial respiratory dysfunction.

Exercise, especially high-intensity interval training (HIIT), can increase mitochondrial respiratory capacity and enhance muscular endurance, but its systemic burden makes it difficult to safely and continuously prescribe for patients with chronic kidney disease (CKD)-related cachexia who are in poor general condition. In this study, we examined whether HIIT using electrical stimulation (ES), which does not require whole-body exercise, improves muscle endurance in the skeletal muscle of 5/6 nephrectomized rats, a widely used animal model for CKD-related cachexia. Male Wistar rats (10weeks old) were randomly assigned to a group of sham-operated (Sham) rats and a group of 5/6 nephrectomy (Nx) rats. HIIT was performed on plantar flexor muscles in vivo with supramaximal ES every other day for 4weeks to assess muscle endurance, myosin heavy-chain isoforms, and mitochondrial respiratory function in Nx rats. A single session was also performed to identify upstream signaling pathways altered by HIIT using ES. In the non-trained plantar flexor muscles from Nx rats, the muscle endurance was significantly lower than that in plantar flexor muscles from Sham rats. The proportion of myosin heavy chain IIa/x, mitochondrial content, mitochondrial respiratory capacity, and formation of mitochondrial respiratory supercomplexes in the plantaris muscle were also significantly decreased in the non-trained plantar flexor muscles from Nx rats than compared to those in plantar flexor muscles from Sham rats. Treatment with HIIT using ES for Nx rats significantly improved these molecular and functional changes to the same degrees as those in Sham rats. Furthermore, a single session of HIIT with ES significantly increased the phosphorylation levels of AMP-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase (MAPK), pathways that are essential for mitochondrial activation signaling by exercise, in the plantar muscles of both Nx and Sham rats. The findings suggest that HIIT using ES ameliorates muscle fatigue in Nx rats via restoration of mitochondrial respiratory dysfunction with activation of AMPK and p38 MAPK signaling. Our ES-based HIIT protocol can be performed without placing a burden on the whole body and be a promising intervention that is implemented even in conditions of reduced general performance status such as CKD-related cachexia.

Investigating the circulating sphingolipidome response to a single high-intensity interval training session within healthy females and males in their twenties (SphingoHIIT): Protocol for a randomised controlled trial

Introduction: Growing scientific evidence indicates that sphingolipids predict cardiometabolic risk, independently of and beyond traditional biomarkers such as low-density lipoprotein cholesterol. To date, it remains largely unknown if and how exercise, a simple, low-cost, and patient-empowering modality to optimise cardiometabolic health, influences sphingolipid levels. The SphingoHIIT study aims to assess the response of circulating sphingolipid species to a single session of high-intensity interval training (HIIT). Methods: This single-centre randomised controlled trial (RCT) will last 11 days per participant and aim to include 32 young and healthy individuals aged 20-29 (50% females). Participants will be randomly allocated to the HIIT (n= 16) or control groups (physical rest, n= 16). Participants will self-sample fasted dried blood spots for three consecutive days before the intervention (HIIT versus rest) to determine baseline sphingolipid levels. Dried blood spots will also be collected at five time points (2, 15, 30, 60min, and 24h) following the intervention (HIIT versus rest). To minimise the dietary influence, participants will receive a standardised diet for four days, starting 24 hours before the first dried blood sampling. For females, interventions will be timed to fall within the early follicular phase to minimise the menstrual cycle's influence on sphingolipid levels. Finally, physical activity will be monitored for the whole study duration using a wrist accelerometer. Ethics and dissemination: The Ethics Committee of Northwest and Central Switzerland approved this protocol (ID 2022–00513). Findings will be disseminated in scientific journals and meetings. Trial Registration The trial was registered on www.clinicaltrials.gov (NCT05390866, https://clinicaltrials.gov/ct2/show/NCT05390866) on May 25, 2022.

Investigating the circulating sphingolipidome response to a single high-intensity interval training session within healthy females and males in their twenties (SphingoHIIT): Protocol for a randomised controlled trial

Introduction: Growing scientific evidence indicates that sphingolipids predict cardiometabolic risk, independently of and beyond traditional biomarkers such as low-density lipoprotein cholesterol. To date, it remains largely unknown if and how exercise, a simple, low-cost, and patient-empowering modality to optimise cardiometabolic health, influences sphingolipid levels. The SphingoHIIT study aims to assess the response of circulating sphingolipid species to a single session of high-intensity interval training (HIIT). Methods: This single-centre randomised controlled trial (RCT) will last 11 days per participant and aim to include 32 young and healthy individuals aged 20-29 (50% females). Participants will be randomly allocated to the HIIT (n= 16) or control groups (physical rest, n= 16). Participants will self-sample fasted dried blood spots for three consecutive days before the intervention (HIIT versus rest) to determine baseline sphingolipid levels. Dried blood spots will also be collected at five time points (2, 15, 30, 60min, and 24h) following the intervention (HIIT versus rest). To minimise the dietary influence, participants will receive a standardised diet for four days, starting 24 hours before the first dried blood sampling. For females, interventions will be timed to fall within the early follicular phase to minimise the menstrual cycle's influence on sphingolipid levels. Finally, physical activity will be monitored for the whole study duration using a wrist accelerometer. Ethics and dissemination: The Ethics Committee of Northwest and Central Switzerland approved this protocol (ID 2022–00513). Findings will be disseminated in scientific journals and meetings. Trial Registration The trial was registered on www.clinicaltrials.gov (NCT05390866, https://clinicaltrials.gov/ct2/show/NCT05390866) on May 25, 2022.

Abstract 10641: Changes in Oxygen Uptake Parameters Across High-Intensity Intervals Prescribed Using Rating of Perceived Exertion in Cardiac Rehabilitation

Introduction: High intensity interval training (HIIT) during early outpatient cardiac rehabilitation (CR) improves peak oxygen uptake (VO 2 ) and reduces mortality in patients with cardiovascular disease. In a CR setting, prescribing interval intensity using rating of perceived exertion (RPE) is more feasible than using percent of VO 2peak . Additionally, prescribing HIIT with RPE may allow for progressive changes in the VO 2 response throughout a single HIIT session. However, the acute cardiopulmonary responses during individual intervals of HIIT prescribed via RPE in CR are unknown. Hypothesis: We hypothesized that VO 2peak would increase and time-to-peak (TTP) would shorten across high-intensity intervals during a single HITT session prescribed with RPE. Methods: Patients with CAD (N=14; 2 women; 56±9 yrs; 30.46±4.7 kg/m 2 ) referred to CR after an acute coronary event completed a minimum of 25 supervised HIIT sessions during which VO 2 was measured continuously. Each HIIT session included 5 or more (6±1 sessions) 1-minute high intensity intervals (target RPE: 15-17) separated by a 3 to 5-minute low intensity interval (target RPE: <12). The first and last HIIT sessions were used for analysis. VO 2peak was defined as the highest 3-breath averaged VO 2 during or up to 1 minute following each high intensity interval. Results: RPE was 15±2 and 11±2 during the high and low intensity intervals, respectively. Compared to the first HIIT session, VO 2peak was greater during the high intensity intervals of the last HIIT session (25.4±1.5 vs. 21.8±1.1 mL/kg/min; p=0.04). During the first and last HIIT sessions, VO 2peak increased across high intensity intervals (p<0.001). Although TTP was not significantly reduced across intervals during the first HIIT session (p=0.14), TTP was reduced across intervals during the last HIIT session (first interval: 67±19 vs. last interval: 58±9 s; p<0.01). Conclusions: Prescribing HIIT with RPE resulted in increased VO 2peak across high intensity intervals within single HIIT sessions and shortened TTP during high intensity intervals across CR. These findings provide evidence for a priming effect on VO 2peak during HIIT which may contribute to greater cardiopulmonary adaptations in CAD patients.

Blood Pressure and Heart Rate Variability Responses to High-intensity Interval Training in Untrained Postmenopausal Women

ABSTRACT Purpose: The aim of this study was to analyze the blood pressure (BP) and heart rate variability (HRV) responses in untrained postmenopausal women submitted to acute single sessions of high-intensity interval training (HIT). Method: Sixteen postmenopausal women (59.9 ± 5.6 years, 26.7 ± 3.0 kg/m2) participated in a random order of two acute sessions in a balanced crossover format: control without exercise in sitting position or HIT session. BP and heart rate (HR) were recorded before and during 60 min following the sessions. Results: Diastolic (DBP), mean BP (MBP), and double product (DPO) showed interaction (p < .01). DBP, MBP, and DPO increased (p < .01) after HIT but not after the control session. The area under the curve (AUC) of DBP (p = .02) and DPO (p < .01) were different between conditions. Time and frequency indices of HRV presented interaction (p < .05) which impaired these indices post-HIT, but not post-control. The AUC of time and frequency HRV indices were different between conditions. Conclusions: A single session of HIT may increase BP and cardiac stress and cause perturbation of the autonomic function in untrained postmenopausal women.

Acute effect of HIIT on testosterone and cortisol levels in healthy individuals: A systematic review and meta-analysis.

To determine the acute effect of a single high-intensity interval training (HIIT) session on testosterone and cortisol levels in healthy individuals, a systematic search of studies was conducted in MEDLINE and Web of Science databases from inception to February 2020. Meta-analyses were performed to establish the acute effect of HIIT on testosterone and cortisol levels immediately after a single HIIT session; after 30min and 60min (primary outcomes); and after 120min, 180min, and 24h (secondary outcomes, only for pre-post intervention groups). Potential effect-size modifiers were assessed by meta-regression analyses and analyses of variance. Study quality was assessed using the Cochrane's risk of bias tool and the Physiotherapy Evidence Database scale. The meta-analyses of 10 controlled studies (213 participants) and 50 pre-post intervention groups (677 participants) revealed a significant increase in testosterone immediately after a single HIIT session (d=0.92 and 0.52, respectively), which disappeared after 30min (d=0.18 and -0.04), and returned to baseline values after 60min (d=-0.37 and -0.16). Significant increases of cortisol were found immediately after (d=2.17 and 0.64), after 30min (d=1.62 and 0.67) and 60min (d=1.32 and 0.27). Testosterone and cortisol levels decreased significantly after 120min (d=-0.48 and -0.95, respectively) and 180min (d=-0.29 and -1.08), and returned to baseline values after 24h (d=0.14 and -0.02). HIIT components and participant's characteristics seem to moderate the effect sizes. In conclusion, testosterone and cortisol increase immediately after a single HIIT session, then drop below baseline levels, and finally return to baseline values after 24h. This meta-analysis provides a better understanding of the acute endocrine response to a single HIIT session, which would certainly be valuable for both clinicians and coaches in the prescription of exercise programs to improve health and performance. Testosterone and cortisol may be used as sensitive biomarkers to monitor the anabolic and catabolic response to HIIT.

Acute effect of high-intensity interval training exercise on redox status in the ovaries of rats fed a high-fat diet.

This study demonstrates the effect of a single high-intensity interval training (HIIT) session on the redox status of rat ovaries with excess adiposity. Forty Wistar female rats (mean (±s.e.m.) weight 94.40 ± 13.40 g) were divided into two groups and fed either a standard diet (SD) or a high-fat diet (HFD) for 62 days. At the end of this period, the rats were subjected to a single HIIT session and were killed 24 h after exercise. Both groups subjected to exercise (SDex and HFDex) generated a significantly higher antioxidant environment by presenting a higher thiol content, which represents a lower oxidation rate of GSH than their respective controls (SD and HFD). The percentage of morphologically normal primary follicles decreased, whereas that of antral follicles increased, in the SDex group. In addition, the HFD group had a higher percentage of degenerated antral follicles than the SD and SDex groups. Cells immunoreactive for α-smooth muscle actin were seen in the cortical stroma and thecal layer enclosing late secondary and tertiary follicles in all groups. Moreover, heme oxygenase and cytochrome P450 family 19 subfamily A member 1 (Cyp19A1) labelling was seen in all antral follicles. Progesterone concentrations were significantly higher in the HFDex than SDex group. In conclusion, this study indicates that a single session of HIIT may result in an improvement in ovary redox status because of metabolic muscle activity by inducing physiological adaptation after exercise in a paracrine manner.

Does a HIIT modulate BDNF levels, and epigenetic and muscle damage markers in postmenopausal obese women?

Recent clinical studies demonstrated that single bouts of exercise including high intensity interval training (HIIT) protocols are able to modulate muscle damage and epigenetic markers as well as brain-derived neurotrophic factor (BDNF) levels in different populations, however, this relationship is lacking in obese women. To evaluate the impact of a single bout of HIIT on creatine kinase (CK), BDNF and global histone H3 and H4 acetylation levels in obese postmenopausal women. The sample consisted of 10 volunteers with a body mass index of 27 to 39.9 kg / m2 that were submitted to a single session of HIIT on a cycle ergometer for 60 s (separated by 75 s of active recovery). In order to measure the biomarkers, blood samples (15 ml) were collected immediately before and immediately after the intervention. Our protocol did not modify any biomarkers (P&gt;0.05), although a negative correlation between fat mass and global histone H3 levels (P=0.022) and between oxygen consumption and global histone H4 levels (P=0.003) were found. A single bout of HIIT on a cycle ergometer is not an effective strategy to modulate histone acetylation status, CK and BDNF levels in postmenopausal obese women. Future studies considering different exercise protocols should be done in order to elucidate this issue.

The effects of High- versus Moderate-Intensity Exercise on Fatigue in Sarcoidosis.

Background: Fatigue is a common symptom in patients with sarcoidosis. Despite lacking evidence on whether high-intensity interval training (HIIT) will aggravate fatigue, moderate-intensity exercise is often recommended. This study aimed to investigate whether a single session of HIIT would affect fatigue differently from a single session of moderate-intensity continuous training (MICT). Methods: Forty-one patients with pulmonary sarcoidosis were recruited to a cross-over study. All patients completed one treadmill session of HIIT (85% of peak heart rate (HRpeak)) and one of MICT (70% of HRpeak). Fatigue was assessed with the Visual Analogue Scale 0–100 mm, before (T0), after (T1), and 24 hours after (T2) each exercise session. Paired sample t-test was used to compare changes in fatigue from T0 to T1 and from T0 to T2 between HIIT and MICT. Results: No statistically significant difference in fatigue levels was found between HIIT and MICT, either at T1 (3.6 (13.5) and 1.4 (13.5)) or at T2 (8.2 (17.0) and 2.1 (17.1)). Conclusions: A single session of HIIT did not affect fatigue differently than a single session of MICT. These preliminary findings support the need for further research on the long-term effect of HIIT on fatigue in patients with sarcoidosis.

Exercise alters and β-alanine combined with exercise augments histidyl dipeptide levels and scavenges lipid peroxidation products in human skeletal muscle.

Carnosine and anserine are dipeptides synthesized from histidine and β-alanine by carnosine synthase (ATPGD1). These dipeptides, present in high concentration in the skeletal muscle, form conjugates with lipid peroxidation products such as 4-hydroxy trans-2-nonenal (HNE). Although skeletal muscle levels of these dipeptides could be elevated by feeding β-alanine, it is unclear how these dipeptides and their conjugates are affected by exercise training with or without β-alanine supplementation. We recruited 20 physically active men, who were allocated to either β-alanine or placebo-feeding group matched for peak oxygen consumption, lactate threshold, and maximal power. Participants completed 2 wk of a conditioning phase followed by 1 wk of exercise training, a single session of high-intensity interval training (HIIT), followed by 6 wk of HIIT. Analysis of muscle biopsies showed that the levels of carnosine and ATPGD1 expression were increased after CPET and decreased following a single session and 6 wk of HIIT. Expression of ATPGD1 and levels of carnosine were increased upon β-alanine-feeding after CPET, whereas ATPGD1 expression decreased following a single session of HIIT. The expression of fiber type markers myosin heavy chain I and IIa remained unchanged after CPET. Levels of carnosine, anserine, carnosine-HNE, carnosine-propanal, and carnosine-propanol were further increased after 9 wk of β-alanine supplementation and exercise training but remained unchanged in the placebo-fed group. These results suggest that carnosine levels and ATPGD1 expression fluctuates with different phases of training. Enhancing carnosine levels by β-alanine feeding could facilitate the detoxification of lipid peroxidation products in the human skeletal muscle.NEW & NOTEWORTHY Carnosine synthase expression and carnosine levels are altered in the human skeletal muscle during different phases of training. During high-intensity interval training, β-alanine feeding promotes detoxification of lipid peroxidation products and increases anserine levels in the skeletal muscle.

Modification of Blood Redox Homeostasis by High-Intensity Interval Training

Sprint interval training, a high-intensity interval training (HIIT) modality, is associated with improved plasma antioxidant capacity, which suggests that sprint interval training may have potential positive effects on health promotion. However, because its strenuous nature, sprint interval training may intimidate sedentary individuals. This study investigated the acute and chronic effects of HIIT on blood redox homeostasis, using a training protocol based on a higher number of bouts, of increased duration, performed at 90‒110% of aerobic peak power. Seventeen healthy physically active young men performed a single HIIT session, in cycle ergometer, composed of eight bouts of 1 min at 90% of peak power, intercalated with 75 s-intervals of active recovery at 30 W. The plasma total antioxidant capacity was lower immediately after exercise (p = 0.05), an indicative of increased generation of reactive species in response to HIIT, and erythrocyte superoxide dismutase activity was increased (p = 0.03). No effect of acute HIIT session on blood thiobarbituric acid reactive substances (TBARS) content was observed. Nine of the initial seventeen volunteers engaged in a four-week progressive HIIT program, 3 days per week, totaling 12 training sessions. Each training session involved 8–12 cycling exercise bouts, at 90‒110 % peak power for 60 s with active recovery intervals of 75 s at 30 W. The plasma total antioxidant capacity as well as erythrocyte catalase activity were increased in response to training (p < 0.01 and p = 0.03, respectively), which may have contributed to the reduced TBARS content observed with erythrocytes (p = 0.05). Because HIIT improves blood redox homeostasis, it may have a potential therapeutic effect on the treatment of diseases related to redox imbalance, besides its health promotion effects.

One night of partial sleep deprivation impairs recovery from a single exercise training session.

The effects of sleep deprivation on physical performance are well documented, but data on the consequence of sleep deprivation on recovery from exercise are limited. The aim was to compare cyclists' recovery from a single bout of high-intensity interval training (HIIT) after which they were given either a normal night of sleep (CON, 7.56 ± 0.63h) or half of their usual time in bed (DEP, 3.83 ± 0.33h). In this randomized cross-over intervention study, 16 trained male cyclists (age 32 ± 7years), relative peak power output (PPO 4.6 ± 0.7Wkg-1) performed a HIIT session at ±18:00 followed by either the CON or DEP sleep condition. Recovery from the HIIT session was assessed the following day by comparing pre-HIIT variables to those measured 12 and 24h after the session. Following a 2-week washout, cyclists repeated the trial, but under the alternate sleep condition. PPO was reduced more 24h after the HIIT session in the DEP (ΔPPO -0.22 ± 0.22Wkg-1; range -0.75 to 0.1Wkg-1) compared to the CON condition (ΔPPO -0.05 ± 0.09Wkg-1, range -0.19 to 0.17Wkg-1, p = 0.008, d = -2.16). Cyclists were sleepier (12h: p = 0.002, d = 1.90; 24h: p = 0.001, d = 1.41) and felt less motivated to train (12h, p = 0.012, d = -0.89) during the 24h recovery phase when the HIIT session was followed by the DEP condition. The exercise-induced 24h reduction in systolic blood pressure observed in the CON condition was absent in the DEP condition (p = 0.039, d = 0.75). One night of partial sleep deprivation impairs recovery from a single HIIT session in cyclists. Further research is needed to understand the mechanisms behind this observation.

High-intensity interval training increases in vivo oxidative capacity with no effect on Pi→ATP rate in resting human muscle

Mitochondrial ATP production is vital for meeting cellular energy demand at rest and during periods of high ATP turnover. We hypothesized that high-intensity interval training (HIT) would increase ATP flux in resting muscle (VPi→ATP) in response to a single bout of exercise, whereas changes in the capacity for oxidative ATP production (Vmax) would require repeated bouts. Eight untrained men (27 ± 4 yr; peak oxygen uptake = 36 ± 4 ml·kg(-1)·min(-1)) performed six sessions of HIT (4-6 × 30-s bouts of all-out cycling with 4-min recovery). After standardized meals and a 10-h fast, VPi→ATP and Vmax of the vastus lateralis muscle were measured using phosphorus magnetic resonance spectroscopy at 4 Tesla. Measurements were obtained at baseline, 15 h after the first training session, and 15 h after completion of the sixth session. VPi→ATP was determined from the unidirectional flux between Pi and ATP, using the saturation transfer technique. The rate of phosphocreatine recovery (kPCr) following a maximal contraction was used to calculate Vmax. While kPCr and Vmax were unchanged after a single session of HIT, completion of six training sessions resulted in a ∼14% increase in muscle oxidative capacity (P ≤ 0.004). In contrast, neither a single nor six training sessions altered VPi→ATP (P = 0.74). This novel analysis of resting and maximal high-energy phosphate kinetics in vivo in response to HIT provides evidence that distinct aspects of human skeletal muscle metabolism respond differently to this type of training.