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Background: Consequences of spinal cord injury (SCI) with a sedentary lifestyle will progress to muscle weakness and muscle atrophy, leading to muscle fatigue. This study aimed to determine the feasibility and preliminary effects of high-intensity interval training (HIIT) using functional electrical stimulation (FES) cycling on changes in thigh muscle volume and muscle strength, in patients with incomplete SCI., Methods: Eight incomplete SCI patients (mean age 50 years; 6 women) with stable SCI paraplegia (mean 6.75 years since injury) participated in the HIIT FES cycling (85%-90% peak Watts; 4 × 4-min intervals) three times a week (over 6 weeks). The main outcomes were adherence, participant acceptability, and adverse events. Secondary outcomes were muscle strength (peak torque) and leg volume changes., Results: Our findings revealed that the program was well-received by participants, with high levels of adherence, positive feedback, and satisfaction, suggesting that it could be a promising option for individuals seeking to enhance their lower body strength and muscle mass. Additionally, all participants successfully completed the training without any serious adverse events, indicating that the program is safe for use. Finally, we found that the 6-week HIIT FES leg cycling exercise program resulted in notable improvements in isometric peak torque of the quadriceps (range 13.9%-25.6%), hamstring muscle (18.2%-23.3%), and leg volume (1.7%-18.2%)., Conclusions: This study highlights HIIT FES leg cycling exercise program potential as an effective intervention for improving lower limb muscle function., (© 2024 International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

Atrial fibrillation (AF), the most common sustained arrhythmia in clinical practice, exhibits a higher risk of cardiovascular adverse events. Exercise plays a crucial role in AF prevention, but the effects of different exercise types and doses are inconclusive. This review aims to comprehensively explore the most recent evidence and possible mechanisms of diverse exercise modalities concerning AF incidence and therapeutic outcomes. Multiple studies underscore the efficacy of moderate-intensity continuous training (MICT) in reducing AF incidence and symptom burden, rendering it the currently favored exercise therapy for AF patients. High-intensity interval training (HIIT) shows promise, potentially surpassing MICT, especially in reducing age-related AF susceptibility and improving symptoms and exercise capacity. Conversely, prolonged high-intensity endurance exercise exacerbates AF risk due to excessive exercise volume, with potential mechanisms encompassing irreversible atrial remodeling, heightened inflammation, and increased vagal tone. In summation, MICT is a secure strategy for populations in mitigating the risk associated with AF incidence and secondary cardiovascular events and should be encouraged. Also, it is recommended to initiate large-scale clinical intervention trials encompassing a variety of exercise types to delineate the optimal exercise prescription for cardiovascular patients, including those afflicted with AF., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: High-intensity interval training (HIT) can provide physiologic benefits and may improve postoperative recovery but has not been evaluated in inpatients. This study aimed to evaluate the safety and tolerability of HIT after major surgery., Methods: We performed a phase I randomized study comparing HIT with low-intensity continuous ambulation (40 m) during the initial inpatient stay after major surgery at a large academic center. Clinicopathologic and pre- and post-exercise physiologic data were captured. Perceived exertion was measured throughout the intervention., Results: Twenty-two subjects were enrolled and randomized with 90% (20 subjects, 10 per arm) completing all aspects of the study. One patient declined participation in the exercise intervention. The HIT and continuous ambulation groups were relatively similar in terms of median age (65.5 vs 63.5), female sex (20% vs 40%), White race (90% vs 90%), having a cancer diagnosis (100% vs 80%), undergoing gastrointestinal surgery (60% vs 80%), median Karnofsky score (60 vs 60), and ability to independently ambulate preoperatively (100% vs 90%). All subjects completed the exercise without protocol deviation, cohort crossover, or safety events. Compared with the continuous ambulation group, the HIT group had higher end median perceived exertion (5.0 [IQR, 5.5] vs 3.0 [IQR, 1.8]), shorter overall time to complete assigned exercise (56.6 seconds vs 91.8 seconds), and a trend toward higher median gait speed over 40 m (0.71 m/s vs 0.44 m/s, P = .126)., Conclusion: HIT in the hospitalized postoperative patient is safe and may be implemented to help promote positive physiologic outcomes and recovery., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to report. The authors report no proprietary or commercial interest in any product mentioned or concept discussed in this article., (Copyright © 2024. Published by Elsevier Inc.)

Women with breast cancer (BC) experience multiple symptoms related to neoadjuvant chemotherapy (NAC) treatment that impair their functioning and quality of life (QoL). This study aimed to explore the effect of high-intensity aerobic interval training (HIIT) on quality of life and NAC side effects in women with BC., Methods: 56 patients (48.56 (7.84) years, range 35-64 years) diagnosed locally advanced (stage II-III) ER + BC receiving doxorubicin/cyclophosphamide-based NAC were randomly assigned to the HIIT group and a control group (CG) for 6 months. The HIIT group performed 2 to 3 HIIT sessions per week according to the study protocol (4 × 4 minutes at 85%-95% peak heart rate (HR)). The CG followed the standard of care instructions by the oncologists. To assess the QoL participants completed the EORTC QLQ-C30 with the additional BC module of QLQ BR-23. Weekly self-reports on NAC side effects were collected through online survey., Results: Study data were analyzed for 37 participants (nHIIT = 17, nCON = 20) who reported at least 14 (60%) weeks. HIIT was effective to reduce BC symptom scale outcomes (ES = 0.113, P  = .048), and alleviate systemic therapy side effects (ES = 0.154, P  = .020) and cancer related symptoms (ES = 0.124, P  = .038). The most common side effect participants experienced at least 1 to 4 days/week was pain (average 50.9% and 56.8% for HIIT and CG, respectively), followed by sleep disturbances (average 50.9% and 49.9%, respectively). About 31% in both groups experienced sleep disturbances 5 to 7 days/week. The NAC induced physical, social and fatigue side effects had significantly lower incidence in HIIT group, while psychological side effects were significantly more common in training group., Conclusions: HIIT is an effective physical exercise program to maintain higher quality of life and help to reduce some of NAC induced side effects for women with BC., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Provision, uptake, adherence, and completion rates for supervised exercise programs (SEP) for intermittent claudication (IC) are low. A shorter, more time-efficient, 6-week, high-intensity interval training (HIIT) program may be an effective alternative that is more acceptable to patients and easier to deliver. The aim of this study was to determine the feasibility of HIIT for patients with IC., Methods: A single arm proof-of-concept study, performed in secondary care, recruiting patients with IC referred to usual-care SEPs. Supervised HIIT was performed three times per week for 6 weeks. The primary outcome was feasibility and tolerability. Potential efficacy and potential safety were considered, and an integrated qualitative study was undertaken to consider acceptability., Results: A total of 280 patients were screened: 165 (59%) were eligible, and 40 (25%) were recruited. The majority (n = 31; 78%) of participants completed the HIIT program. The remaining nine patients were withdrawn or chose to withdraw. Completers attended 99% of training sessions, completed 85% of sessions in full, and performed 84% of completed intervals at the required intensity. There were no related serious adverse events. Maximum walking distance (+94 m; 95% confidence interval, 66.6-120.8 m) and the SF-36 physical component summary (+2.2; 95% confidence interval, 0.3-4.1) were improved following completion of the program., Conclusions: Uptake to HIIT was comparable to SEPs in patients with IC, but completion rates were higher. HIIT appears feasible, tolerable, and potentially safe and beneficial for patients with IC. It may provide a more readily deliverable, acceptable form of SEP. Research comparing HIIT with usual-care SEPs appears warranted., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The present study investigated the glycemic response to an acute high-intensity interval training (HIIT) session (10 one-minute intervals ≥90% HR max interspersed with one-minute of active recovery) versus a moderate-intensity continuous training (MICT) session (30 min at 64%-76% HR max ) during pregnancy. Twenty-four normoglycemic females with a singleton pregnancy (27.8 ± 4.7 weeks of gestation, 31.5 ± 4.1 years of age, body mass index: 25.2 ± 11.3) participated in a randomized crossover design study. A flash glucose monitor and accelerometer were worn continuously for 7 days recording glycemic response, physical activity, and sleep. Nutritional intake and enjoyment of the exercise were self-reported. Average heart rate during exercise was higher for HIIT (82 ± 4% HR max ) compared with MICT (74 ± 4% HR max ; p < 0.001) and participants achieved a peak heart rate of 92 ± 3% during HIIT (range 85%-97% HR max ) compared with 81 ± 4% during MICT (p < 0.001). The change in glucose values from pre-to-postexercise were not different between conditions (HIIT: -0.62 ± 1.00 mmol/L; MICT: -0.81 ± 1.05 mmol/L; p = 0.300) with the exception that fewer individuals experienced postexercise hypoglycemia immediately following HIIT compared with MICT (8% versus 33% respectively; p = 0.041). Other glucose variables was not different between exercise protocols. Physical activity (p = 0.07) and caloric intake did not differ (p = 0.10). The majority of participants preferred HIIT (87.5%) and had greater perceived enjoyment compared to MICT (HIIT: 7.8 ± 1.5; MICT: 6.6 ± 2.0; p = 0.015). Sleep duration was 52 ± 73 min longer after participating in HIIT compared with the night prior (main effect for time p = 0.017); no significant changes for MICT. Overall, an acute session of HIIT appears to be well tolerated and demonstrates no adverse effects on maternal glycemic response., (© 2022 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

The majority of women do not meet the recommended levels of exercise during their pregnancies, frequently due to a lack of time. High-intensity interval training offers a potential solution, providing an effective, time-efficient exercise modality. This exercise modality has not been studied in pregnancy therefore, the objective of this study was to evaluate fetal response to a high-intensity interval training resistance circuit in the late second and early third trimesters of pregnancy. Fourteen active, healthy women with uncomplicated, singleton pregnancies participated in a high-intensity interval training resistance circuit between 28 + 0/7 and 32 + 0/7 weeks. A Borg rating of perceived exertion of 15-17/20 and an estimated heart rate of 80%-90% of maternal heart-rate maximum was targeted. Fetal well-being was evaluated continuously with fetal heart-rate tracings and umbilical artery Doppler velocimetry conducted pre-and post-exercise. Fetal heart rate tracings were normal throughout the exercise circuit. Post-exercise, umbilical artery end-diastolic flow was normal and significant decreases were observed in the mean systolic/diastolic ratios, pulsatility indexes and resistance indexes. Therefore, in a small cohort of active pregnant women, a high-intensity interval training resistance circuit in the late second and early third trimesters of pregnancy appears to be a safe exercise modality with no acute, adverse fetal effects but further study is required. Novelty: High-intensity interval training, at an intensity in excess of current recommendations, does not appear to be associated with any adverse fetal effects in previously active pregnant women. High-intensity interval training is an enjoyable and effective exercise modality in previously active pregnant women.

Aside from its role in bone metabolism, vitamin D is a key immunomodulatory micronutrient. The active form of vitamin D (1,25(OH)D) seems to modulate the innate immune system through different mechanisms. The vitamin is involved in the differentiation of monocytes into macrophages, increasing the phagocytic and chemotactic functions of these cells. At the same time, vitamin D enables efferocytosis and prevents immunopathology. In addition, vitamin D is involved in other processes related to immune function, such as inflammation. Regarding muscle tissue, vitamin D plays an active role in muscle inflammatory response, protein synthesis, and regulation of skeletal muscle function. Two mechanisms have been proposed: A direct role of 1,25(OH)D binding to vitamin D receptors (VDRs) in muscle cells and the modulation of calcium transport in the sarcoplasmic reticulum. This second mechanism needs additional investigation. In conclusion, vitamin D seems to be effective in cases of deficiency and/or if there is a great muscular commitment, such as in high intensity exercises.

Background: This study compared the effect of treadmill running on subsequent upper limb exercise performance in young men., Methods: Seventeen young men (24.8±5.2 years) completed a: 1) bench press resistance exercise control session; 2) treadmill interval running protocol followed by the bench press session; and 3) treadmill continuous running protocol followed by the bench press session. Four sets of the bench press exercise were performed at 80% of 1RM up to volitional failure. In the interval protocol, eight sprints of 40s at 100% of the velocity of maximal oxygen uptake, with 20s of passive interval between them were performed, whereas in the continuous protocol 30-min of treadmill running at 90% of the heart rate corresponding to second ventilatory threshold was performed. The number of maximal repetitions completed in each set and condition was recorded and compared using a two-way repeated measures ANOVA., Results: The interval protocol (18.7±4.9 repetitions) resulted in a reduction in the number of bench press repetitions compared to the control protocol (21.4±5.4 repetitions) (P=0.002); whereas continuous running did not affect the bench press performance (20.6±4.4 repetitions). The total number of repetitions reduced from set to set in all protocols (P<0.001)., Conclusions: The results evidenced an impairment in the upper limb strength performance after high intensity interval, but not moderate intensity continuous running, which has implication for concurrent training planning and prescription.

Background: Cardiac autonomic neuropathy is a common complication of type 2 diabetes mellitus (T2DM), that can be measured through heart rate variability (HRV)-known to be decreased in T2DM. Physical exercise can improve HRV in healthy population, however results are under debate in T2DM. We conducted a systemic review and meta-analysis to assess the effects of physical exercise on HRV in T2DM patients., Method: PubMed, Cochrane, Embase, and ScienceDirect databases were searched for all studies reporting HRV parameters in T2DM patients before and after exercise training, until September 20th 2020, without limitation to specific years. We conducted random-effects meta-analysis stratified by type of exercise for each of the HRV parameters: RR-intervals (or Normal to Normal intervals-NN), standard deviation of RR intervals (SDNN), percentage of adjacent NN intervals varying by more than 50 milliseconds (pNN50), root mean square of successive RR-intervals differences (RMSSD), total power, Low Frequency (LF), High Frequency (HF) and LF/HF ratio. Sensitivity analyses were computed on studies with the highest quality., Results: We included 21 studies (9 were randomized) for a total of 523 T2DM patients: 472 had an exercise training and 151 were controls (no exercise). Intervention was endurance (14 studies), resistance (2 studies), endurance combined with resistance (4 studies), and high intensity interval training (HIIT) (4 studies). After exercise training, all HRV parameters improved i.e. an increase in SDNN (effect size = 0.59, 95%CI 0.26 to 0.93), RMSSD (0.62, 0.28 to 0.95), pNN50 (0.62, 0.23 to 1.00), HF (0.58, -0.16 to 0.99), and a decrease in LF (-0.37, -0.69 to -0.05) and LF/HF (-0.52, -0.79 to -0.24). There were no changes in controls. Stratification by type of exercise showed an improvement in most HRV parameters (SDNN, RMSSD, pNN50, LF, HF, LF/HF) after endurance training, whereas mostly LF/HF was improved after both resistance training and HIIT. Supervised training improved most HRV parameters. Duration and frequency of training did not influence the benefits on HRV., Conclusion: Exercise training improved HRV parameters in T2DM patients which may reflect an improvement in the activity of the autonomic nervous system. The level of proof is the highest for endurance training. Supervised training seemed beneficial., Competing Interests: The authors have declared that no competing interests exist.

Purpose: The purpose of this study was to determine the effects of 3 consecutive days of endurance training in hypoxia on hepcidin responses., Method: Nine active healthy males completed two trials, consisting of 3 consecutive days of endurance training in either hypoxia [fraction of inspired oxygen (F i O 2 ): 14.5%) or normoxia (F i O 2 : 20.9%). On days 1-3, participants performed one 90 min session of endurance training per day, consisting of high-intensity endurance interval exercise [10 × 4 min of pedaling at 80% of maximal oxygen uptake ([Formula: see text]O 2max ) with 2 min of active rest at 30% of [Formula: see text]O 2max ] followed by 30 min of continuous exercise at 60% of [Formula: see text]O 2max . Venous blood samples were collected prior to exercise each day during the experimental period (days 1-4) to determine serum hepcidin, iron, ferritin, haptoglobin, and ketone body concentrations., Result: Serum iron (p < 0.0001), ferritin (p = 0.005) and ketone body (p < 0.0001) concentrations increased significantly in both trials on days 2-4 compared with day 1, with no significant differences between trials. No significant changes in serum haptoglobin concentrations were observed throughout the experimental period in either trial. Serum hepcidin concentrations also increased significantly on days 2-4 compared with day 1 in both trials (p = 0.004), with no significant differences observed between trials., Conclusion: 3 consecutive days of endurance training in hypoxia did not affect hepcidin concentrations compared with endurance training in normoxia.

High-intensity interval training (HIIT) is of scientific interest due its role in improving physical fitness, but the effects of HIIT on bone health need be carefully explored. Further, it is necessary to know whether HIIT effects on bone health are dependent on the physical activity levels. This may be experimentally tested since we have built a large cage (LC) that allows animals to move freely, promoting an increase of spontaneous physical activity (SPA) in comparison to a small cage (SC). Thus, we examined the effects of HIIT on biophysical, biomechanical and biochemical parameters of bone tissue of C57BL/6J mice living in cages of two different sizes: small (SC) or large (LC) cages with 1320 cm 2 and 4800 cm 2 floor space, respectively. Male mice were subdivided into two groups within each housing type: Control (C) and Trained (T). At the end of the interventions, all mice were euthanized to extract the femur bone for biophysical, biomechanical and biochemical analyses. Based a significant interaction from two-way ANOVA, trained mice kept in large cage (but not for trained mice housed in SC) exhibited a reduction of tenacity and displacement at failure in bone. This suggests that long-term HIIT program, in addition with a more active lifestyle correlates with exerts negative effects on the bone of healthy mice. A caution must also be raised about the excessive adoption of physical training, at least regarding bone tissue. On the other hand, increased calcium was found in femur of mice housed in LC. In line with this, LC-C mice were more active (i.e. SPA) than other groups. This implies that an active lifestyle without long-term high intensity physical training seems to play a role in promoting benefits to bone tissue. Our data provides new insights for treatment of osteo-health related disorders.

Purpose: This study investigated the cardiometabolic health of overweight/obese untrained individuals in response to 8 weeks of HIIT and MICT using a field approach, and to 4 weeks of training cessation (TC)., Methods: Twenty-two subjects performed 8 weeks of moderate intensity continuous training (MICT-n = 11) or high-intensity interval training (HIIT-n = 11) (outdoor running), followed by 4 weeks of TC. Cardiorespiratory fitness, body composition, arterial blood pressure, glucose metabolism and blood lipids were measured pre-training (PRE), post-training (POST) and TC., Results: HIIT improved eight indicators of cardiometabolic health ([Formula: see text], BMI, body fat, visceral fat, systolic blood pressure, total cholesterol, fasting glucose and triglycerides-p  < 0.05) while MICT only three ([Formula: see text], BMI, and visceral fat-p  < 0.05). After 4 weeks of TC, four positive adaptations from HIIT were negatively affected ( [Formula: see text], visceral fat, systolic blood pressure and total cholesterol-p  < 0.05) and three in the MICT group ([Formula: see text], BMI and visceral fat, p  < 0.05)., Conclusion: Eight weeks of HIIT performed in a real-world setting promoted a greater number of positive adaptations in cardiometabolic health of individuals with overweight/obese compared to MICT. Most of the positive effects of the HIIT protocol were also found to be longer lasting and maintained after the suspension of high-intensity interval running for 4 weeks. Conversely, all positive effects of MICT protocols were reversed after TC.

Background: High-intensity functional training (HIFT) has become more popular, and the number of practitioners has increased; however, it remains unclear whether perturbations in the immune parameters occur, even after one single bout. Our aim was to examine acute leucocyte, muscle damage, and stress marker responses following a single 'Cindy' workout session, and compare the results between novice and experienced participants., Material and Methods: Twenty-three HIFT practitioners (age 31.0 ± 1.0 years) completed the 'Cindy' workout. They were categorized as novice (3-8 months of experience; n = 10) and experienced (≥18 months; n = 13). White blood cell (WBC) count, plasma creatine kinase (CK) activity, blood cortisol level, and lactate concentration were measured. Blood analysis was performed before (pre-ex), immediately after (post-ex), 30 min after (post-30 min), and 24 h after (post-24 h) a single 'Cindy' workout session., Results: WBC count was higher post-ex (6.8 to 11.8x103/μL) and returned to baseline values within post-30 min (p<0.01). Neutrophil (3.3 to 4.5x103/μL) and lymphocyte levels (2.8 to 5.9x103/μL) were higher post-ex and returned to baseline values after post-24 h, yet lymphocytopoenia (2.2x103/μL) was observed at post-30 min (p<0.01). CK increased post-ex (174.9 to 226.7 U.L-1) and remained elevated post-24 h. Cortisol (14.7 to 17.0 μg/dL) and lactate (1.9 to 13.5 mmol.l-1) responses increased post-ex, but only the lactate level was reduced at post-30 min (p<0.01). The experienced participants had higher WBC, lymphocyte, and cortisol concentrations post-ex than the novice ones (p<0.01)., Conclusions: A single HIFT session elicited significant acute perturbations in WBC count, stress markers, and muscle tissue, which is like other similar regimens. Importantly, the experienced participants showed greater lymphocyte and cortisol responses than the novice ones., Competing Interests: The authors have declared that no competing interests exist.

The randomized "Testicular cancer and Aerobic and Strength Training trial" (TAST-trial) aimed to evaluate the effect of high-intensity interval training (HIIT) on cardiorespiratory fitness during cisplatin-based chemotherapy (CBCT) for testicular cancer (TC). Here, we report on an unexpected high number of thromboembolic (TE) events among patients randomized to the intervention arm, and on a review of the literature on TE events in TC patients undergoing CBCT. Patients aged 18 to 60 years with a diagnosis of metastatic germ cell TC, planned for 3 to 4 CBCT cycles, were randomized to a 9 to 12 weeks exercise intervention, or to a single lifestyle counseling session. The exercise intervention included two weekly HIIT sessions, each with 2 to 4 intervals of 2 to 4 minutes at 85% to 95% of peak heart rate. The study was prematurely discontinued after inclusion of 19 of the planned 94 patients, with nine patients randomized to the intervention arm and 10 to the control arm. Three patients in the intervention arm developed TE complications; two with pulmonary embolism and one with myocardial infarction. All three patients had clinical stage IIA TC. No TE complications were observed among patients in the control arm. Our observations indicate that high-intensity aerobic training during CBCT might increase the risk of TE events in TC patients, leading to premature closure of the TAST-trial., (© 2020 The Authors. International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.)

Importance: High-intensity interval training (HIIT) is recognized as a potent stimulus for improving cardiorespiratory fitness (volume of oxygen consumption [VO2] peak) in patients with coronary artery disease (CAD). However, the feasibility, safety, and long-term effects of HIIT in this population are unclear., Objective: To compare HIIT with moderate-intensity continuous training (MICT) for feasibility, safety, adherence, and efficacy of improving VO2 peak in patients with CAD., Design, Setting, and Participants: In this single-center randomized clinical trial, participants underwent 4 weeks of supervised training in a private hospital cardiac rehabilitation program, with subsequent home-based training and follow-up over 12 months. A total of 96 participants with angiographically proven CAD aged 18 to 80 years were enrolled, and 93 participants were medically cleared for participation following a cardiopulmonary exercise test. Data were collected from May 2016 to December 2018, and data were analyzed from December 2018 to August 2019., Interventions: A 4 × 4-minute HIIT program or a 40-minute MICT program (usual care). Patients completed 3 sessions per week (2 supervised and 1 home-based session) for 4 weeks and 3 home-based sessions per week thereafter for 48 weeks., Main Outcomes and Measures: The primary outcome was change in VO2 peak during the cardiopulmonary exercise test from baseline to 4 weeks. Further testing occurred at 3, 6, and 12 months. Secondary outcomes were feasibility, safety, adherence, cardiovascular risk factors, and quality of life., Results: Of 93 randomized participants, 78 (84%) were male, the mean (SD) age was 65 (8) years, and 46 were randomized to HIIT and 47 to MICT. A total of 86 participants completed testing at 4 weeks for the primary outcome, including 43 in the HIIT group and 43 in the MICT group; 69 completed testing at 12 months for VO2 peak, including 32 in the HIIT group and 37 in the MICT group. After 4 weeks, HIIT improved VO2 peak by 10% compared with 4% in the MICT group (mean [SD] oxygen uptake: HIIT, 2.9 [3.4] mL/kg/min; MICT, 1.2 [3.4] mL/kg/min; P = .02). After 12 months, there were similar improvements from baseline between groups, with a 10% improvement in the HIIT group and a 7% improvement in the MICT group (mean [SD] oxygen uptake: HIIT, 2.9 [4.5] mL/kg/min; MICT, 1.8 [4.3] mL/kg/min; P = .30). Both groups had high feasibility scores and low rates of withdrawal due to serious adverse events (3 participants in the HIIT group and 1 participant in the MICT group). One event occurred following exercise (hypotension) in the HIIT group. Over 12 months, both home-based HIIT and MICT had low rates of adherence (HIIT, 18 of 34 [53%]; MICT, 15 of 37 [41%]; P = .35) compared with the supervised stage (HIIT, 39 of 44 [91%]; MICT, 39 of 43 [91%]; P > .99)., Conclusions and Relevance: In this randomized clinical trial, a 4-week HIIT program improved VO2 peak compared with MICT in patients with CAD attending cardiac rehabilitation. However, improvements in VO2 peak at 12 months were similar for both groups. HIIT was feasible and safe, with similar adherence to MICT over 12-month follow-up. These findings support inclusion of HIIT in cardiac rehabilitation programs as an adjunct or alternative modality to moderate-intensity exercise., Trial Registration: Australian New Zealand Clinical Trials Registry Identifier: ACTRN12615001292561.

Cyclists often apply block periodization to high training volumes in meso- and macrocycles to optimize training adaptation and to prepare for competition. Body mass influences performance in many sports, including endurance disciplines, and conditions related to the syndrome Relative Energy Deficiency in Sports (RED-S) such as metabolic adaptations and premature osteoporosis have also been reported in male cyclists. This study aimed to determine how a 4-week mesocycle of intensified endurance training designed to increase performance, would affect markers of RED-S in well-trained male cyclists. Twenty-two participants (age: 33.5 ± 6.6 years, height: 181.4 ± 5.2 cm, weight: 76.5 ± 7.4 kg, peak oxygen uptake (VO 2peak ): 63.5 ± 6.6 mL·kg -1 ·min -1 ) were recruited and instructed to maintain their background training load and to follow a supervised training protocol consisting of three high-intensity interval training sessions per week with a work duration of 32 min per session. Protocols included pre- and postintervention assessment of resting metabolic rate (RMR) using a ventilated hood, body composition and bone health by dual-energy X-ray absorptiometry (DXA), blood samples, energy intake, and aerobic performance. The interval training increased participants' aerobic performance-peak power output [4.8%, p < 0.001], VO 2peak [2.4%, p = 0.005], and functional threshold power [6.5%, p < 0.001] as well as total testosterone levels [8.1%, p = 0.011]-while no changes were observed in free testosterone [4.1%, p = 0.326]. Bodyweight, body composition, and energy intake were unchanged from pre- to post-test. Triiodothyronine (T 3 ) [4.8%, p = 0.008], absolute RMR [3.0%, p = 0.010], relative RMR [2.6%, p = 0.013], and RMR ratio [3.3%, p = 0.011] decreased, and cortisol levels increased [12.9%, p = 0.021], while no change were observed in the total testosterone:cortisol ratio [1.6%, p = 0.789] or the free testosterone:cortisol (fT:cor) ratio [3.2%, p = 0.556]. A subgroup analysis of the five participants with the largest increase in fT:cor ratio, revealed a greater improvement in functional threshold power (9.5 vs. 2.5%, p = 0.037), and higher relative RMR (0.6 vs. -4.2% p = 0.039, respectively). In conclusion, 4 weeks of intensified endurance interval training increased the athletes' aerobic performance and testosterone levels. However, negative changes in markers related to RED-S, such as a reduction in RMR and T 3 , and an increase in cortisol were observed. These results indicate the complexity involved, and that male athletes are at risk of developing clinical indications of RED-S even during a short 4-week endurance training mesocycle., (Copyright © 2020 Stenqvist, Torstveit, Faber and Melin.)

Background: Cardiovascular disease (CVD) remains the largest cause of death in breast cancer survivors. The aim of this study was to explore the impact of exercise intensity on aerobic fitness and autonomic cardiac regulation (heart rate variability (HRV)) and salivary biomarkers of the stress systems (HPA-axis, cortisol; sympathetic nervous system, α-amylase) and mucosal immunity (secretory(s)-IgA), markers of increased risk of CVD in breast cancer survivors., Methods: Participants were randomly assigned to; 1) high intensity interval training (HIIT); 2) moderate-intensity, continuous aerobic training (CMIT); or 3) a wait-list control (CON) for a 12-week (36 session) stationary cycling intervention. Cardiorespiratory fitness (VO 2peak ), resting HRV and salivary biomarkers were measured at baseline 2-4 d pre-intervention and 2-4 d post the last exercise session., Results: Seventeen participants were included in this study (62 ± 8 years, HIIT; n = 6, CMIT; n = 5, CON; n = 6). A significant improvement (p ≤ 0.05) was observed for VO 2peak in the HIIT group; 19.3% (B = 3.98, 95%CI = [1.89; 4.02]) and a non-significant increase in the CMIT group; 5.6% (B = 1.96, 95%CI = [- 0.11; 4.03]), compared with a 2.6% (B = - 0.64, 95%CI = [- 2.10; 0.82]) decrease in the CON group. Post intervention improvements in HRV markers of vagal activity (log (ln)LF/HF, LnRMSSD) and sympathetic nervous system (α-amylase waking response) occurred for individuals exhibiting outlying (> 95% CI) levels at baseline compared to general population., Conclusion: High intensity interval training improved cardiovascular fitness in breast cancer survivors and improved cardiac regulation, and sympathetic nervous system (stress) responses in some individuals. High-intensity interval training was safe and effective for breast cancer survivors to participate in with promising results as a time efficient intensity to improve physical health and stress, reducing CVD risk., Trial Registration: This pilot study was retrospectively registered through the Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12620000684921 .

Purpose: High intensity interval training (HIIT) has been shown to improve important health parameters, including aerobic capacity, blood pressure, cardiac autonomic modulation and left ventricular (LV) mechanics. However, adaptations in left atrial (LA) mechanics and aortic stiffness remain unclear., Methods: Forty-one physically inactive males and females were recruited. Participants were randomised to either a 4-week HIIT intervention (n = 21) or 4-week control period (n = 20). The HIIT protocol consisted of 3 × 30-s maximal cycle ergometer sprints with a resistance of 7.5% body weight, interspersed with 2-min of active unloaded recovery, three times per week. Speckle tracking imaging of the LA and M-Mode tracing of the aorta was performed pre and post HIIT and control period., Results: Following HIIT, there was significant improvement in LA mechanics, including LA reservoir (13.9 ± 13.4%, p = 0.033), LA conduit (8.9 ± 11.2%, p = 0.023) and LA contractile (5 ± 4.5%, p = 0.044) mechanics compared to the control condition. In addition, aortic distensibility (2.1 ± 2.7 cm 2  dyn -1  10 3 , p = 0.031) and aortic stiffness index (- 2.6 ± 4.6, p = 0.041) were improved compared to the control condition. In stepwise linear regression analysis, aortic distensibility change was significantly associated with LA stiffness change R 2 of 0.613 (p = 0.002)., Conclusion: A short-term programme of HIIT was associated with a significant improvement in LA mechanics and aortic stiffness. These adaptations may have important health implications and contribute to the improved LV diastolic and systolic mechanics, aerobic capacity and blood pressure previously documented following HIIT.

The aim of this study was to determine the acute effects of high-intensity interval training (HIIT) exercise and endurance exercise (EE) on pulmonary function, sympathetic/parasympathetic balance, and cardiorespiratory coupling (CRC) in healthy participants. Using a crossover repeated-measurements design, four females and four males were exposed to EE (20 min at 80% maximal heart rate [HR]), HIIT (1 min of exercise at 90% maximal HR per 1 min of rest, 10 times), or control condition (resting). Pulmonary function, HR, CRC, and heart rate variability (HRV) were assessed before and after the interventions. Results revealed no significant effects of EE or HIIT on pulmonary function. The EE, but not HIIT, significantly increased CRC. In contrast, HRV was markedly changed by HIIT, not by EE. Indeed, both the low-frequency (LF HRV ) and high-frequency (HF HRV ) components of HRV were increased and decreased, respectively, after HIIT. The increase in LF HRV was greater after HIIT than after EE. Therefore, a single bout of HIIT or EE has no effects on pulmonary function. Moreover, CRC and cardiac autonomic regulation are targeted differently by the two exercise modalities., (© 2020 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

Purpose: We investigated whether obesity adversities such as excessive body fat, compensatory hyperinsulinemia, metabolic endotoxemia, irregular androgenicity, and reduced cardiorespiratory and anaerobic fitness are ameliorated by high-intensity interval training (HIIT) with or without caffeine supplementation in women with obesity., Methods: Twenty-four women with obesity (Asian cutoff point body mass index ≥ 27 kg·m, body fat = 40%) were evenly randomized to caffeine (CAF) and placebo (PLA) trials for an 8-wk HIIT program (10 × 1-min sprints, interspersed by 1-min rest). CAF (3 mg·kg·bw) and PLA were supplemented before each training session. Body fat was assessed by dual-energy x-ray absorptiometry before and after training together with assessments of glucose tolerance (oral glucose tolerance test, or OGTT), lipopolysaccharide endotoxins, testosterone, cardiorespiratory, and anaerobic fitness., Results: Significant interaction between HIIT and CAF was found for OGTT glucose and OGTT insulin levels (P = 0.001 and P = 0.049 respectively). HIIT-alone increased glucose at 90 min (P = 0.049) and OGTT insulin at 60 min (P = 0.038). Conversely, HIIT with CAF decreased OGTT glucose at 120 min (P = 0.024) without affecting OGTT insulin. HIIT-alone induced 28.3% higher OGTT insulin (effect size d = 0.59 for area under the curve) and 14.5% higher OGTT glucose (d = 0.28). Conversely, HIIT with CAF decreased OGTT glucose by 19.1% (d = 0.51 for area under the curve) without changing OGTT insulin. HIIT-alone effects on glycemia and insulinemia were concurrent with a 31% increase in lipopolysaccharide endotoxins (P = 0.07; d = 0.78; confidence interval, 5.7-8.7) in the PLA but not in CAF treatment (P = 0.99; d = 0.003; confidence interval, 6.5-10.6), although endotoxin level remained within the recommended healthy thresholds. Furthermore, either HIIT alone or with CAF reduced body fat percentage (P < 0.001, ANOVA main training effects), increased muscle mass (P = 0.002), reduced testosterone (P = 0.005), and increased cardiorespiratory and anaerobic capacity (P < 0.001)., Conclusions: HIIT induces fat loss and decreases androgenicity in women with obesity. However, its side effects such as endotoxemia and hyperinsulinemia are ameliorated by caffeine supplementation.

Case: Hip dislocations with associated acetabular fracture are rare events usually associated with high-energy trauma. We describe an unusual case of low-energy acetabular fracture dislocation sustained by a 30-year-old athletic male athlete during a high-intensity training program., Conclusion: Correct execution of training programs is important. Healthcare professionals as well as participants and instructors of extreme conditioning programs should be aware of this serious complication. Avoidance of this injury may be possible with increased interval recovery and improved technique.

Objective: To examine CrossFit-related injuries based on sex and age., Design: Retrospective case series., Setting: A tertiary-level pediatric sports medicine clinic., Participants: CrossFit athletes., Main Outcome Measures: CrossFit-related injuries by sex (males vs females) and age groups (≤19 years vs >19 years) using a χ analysis with P = 0.05, odds ratio (OR), and 95% confidence interval (95% CI)., Results: Among injured CrossFit athletes, female athletes sustained lower extremity injuries more frequently than male athletes (P = 0.011; OR, 2.65; 95% CI, 1.25-5.65). In observed CrossFit injuries, shoulder injuries were more frequently observed in male athletes compared with female athletes (P = 0.049; OR, 2.79; 95% CI, 0.98-7.95). Additionally, a greater proportion of CrossFit athletes aged 19 years and younger suffered trunk/spine injuries than those older than 19 years (P = 0.027; OR, 2.61; 95% CI, 1.10-6.21) in injured CrossFit athletes., Conclusions: The current results indicated sex- and age-specific susceptibility to CrossFit-related injuries based on body parts and diagnoses. The presented information may be useful to develop a safer exercise program, especially for pediatric and adolescent CrossFit participants.

Interval exercise training is increasingly recommended to improve health and fitness; however, it is not known if cardiovascular risk is different from continuous exercise protocols. This systematic review with meta-analyses assessed the effect of a single bout of interval exercise on cardiovascular responses that indicate risk of cardiac fibrillation and infarction compared to continuous exercise. Electronic databases Medline, CINAHL, Embase, Scopus and Cochrane were searched. Key inclusion criteria were: (1) intervals of the same intensity and duration followed by a recovery period and (2) reporting at least one of blood pressure, heart rate variability, arterial stiffness or function. Cochrane Risk of Bias tool and GRADE approach were used. Meta-analyses found that systolic blood pressure responses to interval exercise did not differ from responses to continuous exercise immediately (MD 8 mmHg [95% CI -32, 47], p = 0.71) or at 60 min following exercise (MD 0 mmHg [95% CI -2, 1], p = 0.79). However, reductions in diastolic blood pressure and flow-mediated dilation with interval exercise were observed 10-15 min post-exercise. The available evidence indicates that interval exercise does not convey higher cardiovascular risk than continuous exercise. Further investigation is required to establish the safety of interval exercise for clinical populations.

Arterial compliance and autonomic regulation are predictors of cardiovascular disease. In adults, both are altered chronically by type 1 diabetes (T1D) and acutely by exercise; however, the effects of T1D and exercise are less clear in adolescents. We measured short-term effects of a high-intensity aerobic interval exercise session on cardiovascular and metabolic variables in normal weight adolescents with T1D or without T1D (Control). Energy expenditure (EE), heart rate variability (HRV), arterial compliance, and blood pressure (BP) were measured before exercise (baseline) and three times over 105 minutes postexercise. The T1D and control groups had similar cardiorespiratory fitness and accelerometer-measured physical activity. The T1D group had higher EE and fat oxidation throughout the trial, but postexercise changes were similar between groups. HRV transiently declined following exercise in both groups, but the T1D group had lower HRV at baseline. Among the measures of arterial compliance, the augmentation index declined postexercise while carotid-femoral pulse wave velocity and large artery elastic index remained unchanged. Central and brachial BP were unchanged following exercise until the final measurement, when a small increase occurred. However, arterial compliance and BP did not differ between groups. These results demonstrate that normal weight adolescents with T1D have impaired autonomic function and increased EE and fat oxidation compared to peers without diabetes who have similar levels of fitness and physical activity. However, acute cardiometabolic responses to exercise are normal in T1D with adequate glycemic control. Changes in arterial compliance and BP may take longer to emerge in relatively healthy adolescents with T1D., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Pectoralis major (PM) tears are a rare injury, that commonly occurs at the sternocostal head and has a greater incidence in men, with only two previously reported cases in young and middle-aged women. The authors report a complete PM tear that occurred in a 23-year-old woman, that presented after performing a 'muscle-up'. MRI revealed PM rupture at the humeral insertion. Surgical management was performed, and patient returned to high-intensity interval training at 11 months postoperatively and reported great satisfaction. This is the first case in literature that reports a complete tear of the PM in a young woman through an atraumatic mechanism of injury with no previous alteration to the PM. With a cultural increase in wellness, atraumatic PM tear in young women should be expected and remain on the differential for any athlete that participates in high-intensity interval training., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Aims: We aimed to examine the feasibility and safety of undertaking high-intensity interval exercise (HIIE) with evening basal insulin dose reduction on exercise-related hypoglycaemia following an afternoon bout of HIIE, compared with moderate-intensity continuous exercise and a non-exercise control day in adults with type 1 diabetes in a free-living environment., Methods: Twelve adults with type 1 diabetes participated in a randomised, crossover trial (9 female/3 male, mean age 40.4 ± 9.9 years, duration 16.5 ± 9.8 years, HbA1c 8.0 ± 0.8%). Each participant undertook five conditions: a non-exercise day, and four exercise conditions on separate afternoons: a moderate-intensity continuous exercise bout; and three HIIE bouts with 10%, 20% and 30% evening basal insulin reduction. Post-exercise glucose response was measured for 24 h by continuous glucose monitoring and compared across conditions., Results: HIIE with 10%, 20% and 30% evening basal insulin dose reduction was not associated with an increase in hypoglycaemia compared with moderate-intensity continuous exercise, or the non-exercise day. There was no difference in hyperglycaemia, time-in-range or glucose variability across all exercise regimens and the non-exercise day (p > .05)., Conclusions: Exercise-related hypoglycaemia was not increased following afternoon HIIE when diabetes management strategies incorporating evening basal insulin dose reduction were utilised., Competing Interests: Declaration of competing interest None of the authors have a conflict of interest to declare, except for Professor Stephen Twigg, who was paid by Abbott Diabetes Care to be on the Australian National Advisory Board for the Freestyle Libre Flash Glucose Monitoring System. In the current study, the Freestyle Libre Pro devices were provided as a gift from Abbott Diabetes Care to enable the study to be undertaken with blinded CGM., (Copyright © 2019. Published by Elsevier Inc.)

Background: Exercise is considered important in the management of patients with rheumatic diseases, but the effect of high intensity exercises on disease activity is unknown., Objective: To investigate the effectiveness of high intensity exercises on disease activity in patients with axial spondyloarthritis (axSpA)., Method: Assessor blinded multicentre randomised controlled trial. 100 patients (aged from their 20s to their 60s) with axSpA were randomly assigned to an exercise group or to a no-intervention control group. The exercise group performed cardiorespiratory and muscular strength exercises at high intensity over 3 months. The control group received standard care and was instructed to maintain their usual physical activity level. Primary outcome was disease activity measured with the Ankylosing Spondylitis (AS) Disease Activity Scale (ASDAS, higher score=worst) and the Bath AS Disease Activity Index (BASDAI, 0-10, 10=worst). Secondary outcomes were inflammatory markers, physical function and cardiovascular (CV)-health. There was patient involvement in the design and reporting of this study., Results: 97 of the 100 (97%) randomised patients completed the measurements after the intervention. There was a significant treatment effect of the intervention on the primary outcome (ASDAS: -0.6 [-0.8 to -0.3], p<0.001 and BASDAI: -1.2 [-1.8 to -0.7], p<0.001). Significant treatment effects were also seen for inflammation, physical function and CV-health., Conclusion: High intensity exercises reduced disease symptoms (pain, fatigue, stiffness) and also inflammation in patients with axSpA. It improves patients' function and CV health. This debunks concerns that high intensity exercise might exacerbate disease activity in patients with axSpA., Trial Registration Number: NCT02356874., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Exercise has beneficial effects on older adults, but controversy surrounds the purported "compensatory effects" that training may have on total daily physical activity and energy expenditure in the elderly. We wanted to determine whether 8 weeks of high-intensity interval training (HIIT) induced such effects on physical activity and energy expenditure in healthy, active older adult men., Methods: Twenty-four healthy elderly male volunteers were randomized to two groups. The experimental group performed HIIT (7 × 2 min cycling repetitions, 3 d/w); the control group performed continuous moderate-intensity training (20-30 min cycling, 3 d/w). Physical activity and energy expenditure were measured with a multisensor activity monitor SenseWear Armband Mini., Results: During HIIT, significant changes were observed in moderate and vigorous physical activity, average daily metabolic equivalents (METs), physical activity level, and activity energy expenditure ( p < 0.05) but not in total energy expenditure. Sleep and sedentary time, and levels of light physical activity remained constant during the training period., Conclusions: The findings suggest that HIIT induced no compensatory effect: HIIT does not adversely affect lifestyle, as it does not reduce daily energy expenditure and/or increase sedentary time.

Objectives: CrossFit comprises a set of high-intensity, high-impact exercises that includes movements that may increase intra-abdominal pressure and cause involuntary loss of urine. There is scant literature about the prevalence of urinary incontinence (UI) in female crossfitters, as well as its associated factors., Methods: A population-based Internet survey stored in a website created with information on the benefits and risks of CrossFit for women's health (https://crosscontinencebr.wixsite.com/crosscontinencebr) invited female crossfitters. In total, 551 women answered an online questionnaire, and the demographic variables (age, marital status, and parity), anthropometric data (weight, height, and body mass index), and the presence of UI during exercises were also investigated. The prevalence of UI and its associated factors were calculated using a logistic regression model. The significance level was set at 5%., Results: The overall prevalence of UI during CrossFit exercises was 29.95%, and most women with UI reported loss of urine during at least one exercise (16.70%). Women with UI were older (33.77 ± 8.03 years) than those without UI (30.63 ± 6.93 years; P < 0.001). Double under (20.15%) and single under (7.99%) were the exercises that were most frequently associated with UI and also the only variables that remained in the final model that caused UI. The duration of CrossFit practice, number of days per week practicing CrossFit, daily time practice, previous vaginal delivery, and mean birth weight were not statistically associated with UI., Conclusions: One-third of female crossfitters presented with UI during exercise. Double under was the exercise that was the most associated with UI.

Objective: To evaluate the prevalence and severity of urinary incontinence (UI) in women who participate in CrossFit classes compared with women who participate in non-CrossFit group fitness classes., Methods: The authors conducted a cross-sectional study of women who participate in either CrossFit or non-CrossFit group fitness classes using an online survey. Participants provided demographic information and completed the Incontinence Severity Index and Urinary Distress Inventory. Participants were recruited from local CrossFit and non-CrossFit gyms, online via social media, and an electronic CrossFit Newsletter. Associated comorbidities, exercises associated with UI, and coping mechanisms for urinary leakage were also assessed., Results: Four hundred twenty-three women meeting inclusion criteria completed the survey, including 322 CrossFit participants and 101 non-CrossFit participants. We found that CrossFit participants were older than non-CrossFit participants and more likely to self-identify as non-Hispanic white. CrossFit participants more commonly reported UI (84% vs 48%, P = <0.001), higher severity of UI (Urinary Distress Inventory score: 20.8 vs 12.5, P < 0.001), and specifically more stress UI (73% vs 47%, P < 0.001). Weightlifting and jumping movements were the most common exercises associated with UI in CrossFit participants. Age and participation in CrossFit are significant and independent predictors of UI., Conclusions: More than 80% of CrossFit participants reported UI and half of these reported moderate-severe UI, as compared with women who participate in non-CrossFit classes, less than half of whom reported UI with a small minority reporting moderate-severe UI. Exercises most associated with UI were jumping and weightlifting.

Repeated sprint exercise can interfere with intramuscular redox balance and cause systemic oxidative stress and muscle damage. There is growing evidence that molecular hydrogen counteracts oxidative and/or inflammatory responses. Therefore, we investigated the effects of molecular hydrogen-rich water (HW) on muscle performance and oxidative stress markers induced by strenuous exercise. A single-blind, crossover, randomized controlled trial has been designed. Eight male volunteers completed two 3-day consecutive exercise tests under two conditions: HW and placebo water (PW). The exercise test included a countermovement jump, maximal voluntary isometric contraction of knee extensors, and sprint cycling. The sprint cycling exercise was comprised three repetitions of 10-second maximal pedaling against a resistance of 7.5% body mass and 110-second active rest (no-load pedaling). Before and after the exercise test, participants drank the 500 mL of HW (5.14 ± 0.03 ppm in H 2 concentration) or PW (0.00 ± 0.00 ppm). At 7 hours before the first exercise test (Day 1), as baseline, and 16 hours after the exercise test on each day, blood samples were obtained. Exercise performances in both conditions were not significantly different over 3 consecutive days. In PW trial, relative changes in biological antioxidant potential/diacron-reactive oxygen metabolites, as an index of systemic antioxidant potential, from baseline gradually decreased as the day passed. However, HW suppressed the reduction in biological antioxidant potential/diacron-reactive oxygen metabolites observed in PW. Drinking HW contributed to the maintenance of the redox status during consecutive days of strenuous exercise and might help prevent accumulative muscular fatigue. The study was approved by the Human Research Ethics Committee of the University of Yamanashi, Japan (approval No. H26-008) on December 17, 2014., Competing Interests: None

Background: The relationship between the frequency of high-intensity interval training (HIIT) and the resultant adaptations is largely unclear., Purpose: This study compared the effects of different frequencies of HIIT with those of moderate-intensity continuous training (MICT) on body composition in overweight or obese adults., Methods: Fifty-six overweight or obese (body mass index = 26.4 ± 2.9) men between 18 and 30 yr old (age = 22.8 ± 3.1 yr) were randomly assigned to the following groups: no-intervention control (CON; n = 14), MICT performed thrice weekly (MICT×3/wk; n = 9), HIIT performed thrice weekly (HIIT×3/wk; n = 14), HIIT performed twice weekly (HIIT×2/wk; n = 10), and HIIT performed once weekly (HIIT×1/wk; n = 9). Each HIIT session consisted of 12 × 1-min bouts at 90% heart rate reserve, interspersed with 11 × 1-min bouts at 70% heart rate reserve. Aerobic capacity, body composition, resting heart rate, vascular function, insulin resistance, and biomarkers of metabolic syndrome risk factor were examined at baseline, after 4 wk, and after 8 wk of intervention., Results: Aerobic capacity and percent fat-free mass significantly increased in all exercise groups compared with those in the CON group (CON vs all exercise groups, P < 0.05), whereas body fat mass and systolic blood pressure significantly decreased after 8 wk of intervention in all exercise groups compared with those in the CON group (CON vs all exercise groups, P < 0.05). Body fat mass significantly decreased after 4 wk in all HIIT groups compared with those in the CON group (CON vs all HIIT groups, P < 0.05) but not in the MICT×3/wk group., Conclusion: These novel results demonstrated that performing HIIT once weekly, even with a lower weekly volume of exercise, improved cardiorespiratory fitness, body composition, and blood pressure in overweight/obese adults. Low-frequency HIIT might be a feasible and effective strategy for the prescription of an initial exercise program for inactive, overweight, or obese young men.

Objective: To compare effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on platelet function in patients undergoing cardiac rehabilitation, as hyper-reactive platelets are involved in atherogenesis and atherothrombosis., Methods: In this single-centre parallel group randomised controlled trial, male patients after an acute coronary syndrome under dual antiplatelet therapy performed MICT or HIIT+MICT for 12 weeks. Main outcome was platelet reactivity measured by the half-maximal concentration (EC 50 ) of platelet agonist thrombin receptor-activating peptide-6 (TRAP-6) in terms of P-selectin expression. EC 50 was determined at baseline, after 6 and 12 weeks, each time at physical rest and on exertion., Results: 82 patients were randomised to MICT or HIIT+MICT. Mean (95% CI) baseline EC 50 values at physical rest were 6.7 µM (6.3 µM to 7.0 µM) TRAP-6. After 6/12 weeks, 36/33 MICT and 34/28 HIIT+MICT patients were examined. HIIT+MICT patients had 0.9 µM (0.4 µM to 1.4 µM)/0.5 µM (-0.1 µM to 1.0 µM) higher EC 50 values than MICT ones, and the propensity of their platelets to form aggregates with monocytes was significantly lower after 12 weeks. Short-term strenuous physical exertion was generally associated with platelet activation and an EC 50 reduction of 0.7 µM (0.6 µM to 0.8 µM). HIIT+MICT patients tended to be fitter after 12 weeks. No serious harms were observed., Conclusions: Including HIIT in cardiac rehabilitation seems to confer additional benefits compared with MICT alone, which should be confirmed in clinical trials with hard endpoints. Exertion-induced platelet activation and hyper-reactivity occur despite dual antiplatelet therapy., Trial Registration Number: NCT02930330; Results., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: This study examined whether the exercise-induced changes in inflammatory cytokines differ between impact and no-impact high-intensity interval exercise, and whether they are associated with postexercise changes in sclerostin., Methods: Thirty-eight females (n = 19, 22.6 ± 2.7 yr) and males (n = 19, 22.3 ± 2.4 yr) performed two high-intensity interval exercise trials in random order (crossover design): running on a treadmill and cycling on a cycle ergometer. Trials consisted of eight repetitions of 1 min running or cycling at ≥90% maximal heart rate, separated by 1 min passive recovery intervals. Blood was collected preexercise and 5 min, 1 h, 24 h, and 48 h postexercise, and it was analyzed for serum levels of interleukins (IL-1β, IL-6, and IL-10), tumor necrosis factor alpha (TNF-α), and sclerostin., Results: Inflammatory cytokines significantly increased over time in both sexes with some differences between trials. Specifically, IL-1β significantly increased from pre- to 5 min after both trials (23%, P < 0.05), IL-6 increased 1 h after both trials (39%, P < 0.05), IL-10 was elevated 5 min after running (20%, P < 0.05) and 1 h after both running and cycling (41% and 64%, respectively, P < 0.05), and TNF-α increased 5 min after running (10%, P < 0.05). Sclerostin increased 5 min after both trials, with a greater increase in males than that in females (62 vs 32 pg·mL in running, P = 0.018; 63 vs 30 pg·mL in cycling, P = 0.004). In addition, sclerostin was significantly correlated with the corresponding changes in inflammatory cytokines, and 34% of the variance in its postexercise gain score (Δ) was explained by sex and the corresponding gain scores in TNF-α, which was the strongest predictor., Conclusion: A single bout of either impact or no-impact high-intensity exercise induces changes in inflammatory cytokines, which are associated with the postexercise increase in sclerostin.

Purpose: High-intensity interval training (HIIT) is a time-efficient and promising tool for enhancing physical fitness. However, there is lack of research concerning safety and feasibility of HIIT in cancer survivors. Therefore, two different HIIT protocols were investigated in terms of safety, feasibility, and acute exercise responses., Methods: Forty cancer survivors (20 breast and 20 prostate cancer survivors, 62.9 ± 9.2 yr, BMI 27.4 ± 3.9 kg·m, 6 to 52 wk after the end of primary therapy) completed a maximal cardiopulmonary exercise test and two HIIT protocols on a cycle ergometer: 10 × 1 min at peak power output (10 × 1) and 4 × 4 min at 85%-95% peak HR (4 × 4). Safety (adverse events), acute physiological responses (HR, blood lactate concentration) and acute psychological responses (RPE, enjoyment) were recorded., Results: No major but three minor adverse events occurred. Ninety-five percent of participants were able to complete each HIIT protocol. Estimated energy expenditure (159 ± 15 vs 223 ± 45 kcal, P < 0.001), HR (128 ± 20 vs 139 ± 18 bpm; P < 0.001), blood lactate concentration (5.4 ± 1.0 vs 5.9 ± 1.9 mmol·L; P = 0.035), and RPE legs/breathing (13.8 ± 2.0/13.1 ± 2.0 vs 14.6 ± 2.1/14.3 ± 2.0; P = 0.038/0.003) were significantly higher in the 4 × 4. Enjoyment did not differ between protocols (P = 0.301)., Conclusions: The two HIIT protocols as single sessions appear safe and in the vast majority of breast and prostate cancer survivors after the end of primary therapy also feasible and enjoyable. The 4 × 4 elicited higher energy expenditure and higher cardio-circulatory and metabolic strain and might therefore be preferred if a high training stimulus is intended.

Purpose: This trial aimed to demonstrate the feasibility of high-intensity interval training (HIIT) in postmenopausal, overweight/obese women at high risk of invasive breast cancer and to explore HIIT on changes in cardiorespiratory fitness (CRF), body weight, and body mass index (BMI) compared with moderate-intensity continuous training (MICT) and usual care (UC)., Methods: Forty-four women were randomized to HIIT, MICT, or UC for a 12-wk, thrice weekly, supervised exercise intervention. HIIT included a 5-min warm-up at 50%-70% HRpeak, four cycles of 4 min at 90%-100% HRpeak, followed by 3 min at 50%-70% HRpeak. MICT consisted of 41 min at 60%-70% HRpeak. Feasibility was assessed by consent, adherence, compliance, and retention rates. CRF, body weight, and BMI were measured at baseline and end of study. Repeated-measures linear mixed models were used to assess within- and between-group differences., Results: Average age was 63.9 ± 8.8 yr. BMI was 30.9 ± 5.7 kg·m. Participants completed 90% and 89% of HIIT and MICT workouts, respectively, with 100% compliance to the exercise prescriptions. No serious adverse events were reported. Compared with MICT and UC, HIIT exhibited improvements in change in treadmill time (101 s greater than MICT, and 125 s greater than UC, respectively, P < 0.001). Compared with UC, HIIT exhibited improvement in changes in absolute and relative V˙O2peak (a 0.15-L·min increase, P = 0.005, and a 2.3-mL·kg⋅min increase, P = 0.004). There were no significant differences between groups for body weight or BMI (P > 0.05)., Conclusions: HIIT is feasible, safe, and seems to promote greater improvements in CRF compared with MICT and UC in women at high risk for breast cancer.

Objective: The aims of the study were to assess the feasibility of performing acupuncture on multiple adolescent athletes in a warm weather, high-intensity training environment and to measure perceived effects of acupuncture on delayed-onset muscle soreness and sense of well-being., Design: This is a prospective feasibility study (registered clinical trial NCT03478800). Forty-two healthy male participants, aged 13-18 yrs, were involved in at least 1 of 5 treatment days for a total of 147 individual treatment sessions. Fifteen-minute treatments of traditional needle acupuncture were administered at the football field. Time, cost, adverse effects, and participant/provider ratio were observed. Effect on delayed-onset muscle soreness and sense of well-being were measured via pretreatment and posttreatment visual analog scale (0-10) rating analyses., Results: The results are as follows: time required by research staff on treatment days, 75 mins; total cost, US $700; temperature range, 21°C-28°C; and largest participant to acupuncturist ratio, 7-10:1. No major adverse effects occurred; 55% reported minimal adverse effects, such as mild focal numbness or tingling. Overall pretreatment to posttreatment effect on delayed-onset muscle soreness (average over 5 days) demonstrated significantly improved posttreatment scores (pre 4.6 ± 2.0; post 2.9 ± 2.2, P < 0.001). There was no significant effect on sense of well-being (P = 0.12)., Conclusions: Effectively providing acupuncture to multiple adolescent football players in their training environment is feasible with appropriate staff and resources. Despite mild adverse effects, treatment was well tolerated. This study provides guidance on acupuncture delivery to other athletes in their training environments.

Objective: To assess the reliability of self-perception of glycemia during high-intensity interval training (HIIT) in subjects with type 1 diabetes., Research Design and Methods: This randomized crossover study included subjects who completed four fasted HIIT sessions. Subjects answered the Edinburgh Hypoglycemia Scale, estimated their blood glucose (BG), and had plasma glucose (PG) collected throughout exercise and recovery., Results: As PG increased throughout exercise, hypoglycemia scores increased across each category: autonomic (3.1-4.4, P < 0.05), neuroglycopenic (1.5-2.4, P < 0.05), and nonspecific (1.3-1.9, P < 0.05). Subjects' estimated BG showed a negative bias that widened as exercise progressed and peaked at -1.6 ± 3.3 mmol/L ( P < 0.001) postinsulin correction., Conclusions: During HIIT, despite progressing hyperglycemia, subjects experience increased hypoglycemia symptoms and tend to underestimate their BG level., (© 2019 by the American Diabetes Association.)

The eucapnic voluntary hyperpnea (EVH) challenge is used to determine the presence of exercise-induced bronchoconstriction (EIBC) by monitoring changes in forced expiratory volume in 1 s (FEV 1 ). However, the predictability of the post-EVH decline in FEV 1 on post-exercise FEV 1 remains unclear. Participants completed an EVH challenge to confirm EIBC and completed a continuous exercise (CONT; n = 21), high-intensity interval exercise (HI; n = 13), and sprint interval exercise (SPRT; n = 8) sessions on separate days. FEV 1 was assessed pre- and post exercise. A 1% decline in FEV 1 , post EVH was associated with 0.44%, 0.85%, and 0.56% declines in FEV 1 post CONT, post HI, and post SPRT, respectively. The decline in FEV 1 following the EVH challenge was associated with the decline in FEV 1 following all exercise conditions, with the strongest association being observed following HI. These findings may have implications for exercise prescription and asthma education for recreationally active adults with EIBC.

Background: CrossFit is a strength and conditioning training program, that begin very popular in the last ten years. One of the most concerned characteristics of model is the high intensity activity performed under fatigue conditions that was proposed as potential risk of injuries; current literature on this topic was not conclusive. The purpose of this research was to examine injury epidemiology and risk factors for injury in CrossFit., Methods: This is a retrospective observational study carried out by an anonymous, self-administered questionnaire in a convenience sample of CrossFit athletes., Results: The questionnaire was completed and returned by 454 subjects, of which 325 (71.6%) were male with an average age of 28.8±7.9. 39.9% reported skeletal or muscles injury after to start training CrossFit. Lifetime Prevalence is 0.23 events per year of training/person. The average number of muscles and skeletal injuries reported was of 1.96±1.36. A percentage of 16.7% reported tendinitis. Time of CrossFit training is a determinant of tendinitis (aOR=1.02; P=0.021). Attending the On-Ramp program seemed to protect against the occurrence of injuries., Conclusions: According our results the risk of injury in the CrossFit practice is acceptable and, as discussed in a recent published review, CrossFit is comparable to other exercise programs with similar injury rates and health outcomes.

Objectives . Evaluate the effects of a 6-month High Intensity Interval Training (HIIT) program on (1) functional capacity and health-related quality of life, (2) multiple blood biomarkers, (3) echocardiographic parameters, and (4) exercise performance, in patients in cardiac resynchronization therapy (CRT) stratified by the presence of atrial fibrillation (AF), targeting the following questions: (1) Does CRT provide similar benefits in patients in AF and sinus rhythm (SR)?; and (2) Does HIIT provides similar benefits in patients in AF and SR? Design. Estimates were available at baseline and 6 months after CRT implantation in 37 patients with heart failure. Patients were randomized after CRT to a 24-week HIIT group or to a usual care group (CON). In this sub-analysis, HIIT (AF = 7; SR = 11) and CON (AF = 9; SR = 10) were stratified by the presence of AF. Results. Patients in AF benefitted to a lesser degree from CRT in functional status than patients in SR (23.8-46.0%). However, HIIT induced superior improvements in patients in AF compared to CON (23.9-61.0%). Decreases in TNF-α (8.5-42.9%), BNP (15.3-34.6%) and left ventricular mass (9.6-26.2%) were only observed in patients in SR, whereas increases in peak oxygen uptake were only observed in patients in AF (19.5-23.2%). HIIT improved exercise capacity (8.8-59.4%) in patients in SR. Conclusions. Patients in AF or SR undergoing CRT demonstrated distinct benefits from device implantation and from HIIT as an adjunctive therapeutic strategy. This suggests that both mainstay and adjunctive therapeutics may need to be managed differently in patients in AF and SR.

Purpose: To compare the effects of high-intensity interval training (HIIT) and moderate-intensity training (CONT), matched for total work, on cardiorespiratory coordination and aerobic fitness., Methods: This is a two-arm parallel group single-blind randomised study. Twenty adults were assigned to 6 weeks of HIIT or volume-matched CONT. Participants completed a progressive maximal cycling test before and after the training period. Principal component (PC) analysis was performed on the series of cardiorespiratory variables to evaluate dimensionality of cardiorespiratory coordination, before and after lactate turnpoint. PC 1 eigenvalues were compared., Results: Both HIIT and CONT improved aerobic fitness (main effects of time, p < 0.001, [Formula: see text] ≥ 0.580), with no differences between groups. CONT decreased the number of PCs from two to one at intensities both below and above the lactate turnpoint; PC 1 eigenvalues increased after CONT both below (Z = 2.08; p = 0.04; d = 0.94) and above the lactate turnpoint (Z = 2.10; p = 0.04; d = 1.37). HIIT decreased the number of PCs from two to one after the lactate turnpoint only; PC 1 eigenvalues increased after HIIT above the lactate turnpoint (Z = 2.31; p = 0.02; d = 0.42)., Conclusions: Although CONT and HIIT improved aerobic fitness to a similar extent, there were different patterns of change for cardiorespiratory coordination. These changes appear training-intensity specific and could be sensitive to investigate the individual response to endurance training.

Purpose: This study examined the effects of combined cooling and lower body heat maintenance during half-time on second-half intermittent sprint performances., Methods: In a repeated measures design, nine males completed four intermittent cycling trials (32.1 ± 0.3 °C and 55.3 ± 3.7% relative humidity), with either one of the following half-time recovery interventions; mixed-method cooling (ice vest, ice slushy and hand cooling; COOL), lower body passive heating (HEAT), combined HEAT and COOL (COMB) and control (CON). Peak and mean power output (PPO and MPO), rectal (T re ), estimated muscle (T es-Mus ) and skin (T SK ) temperatures were monitored throughout exercise., Results: During half-time, the decrease in T re was substantially greater in COOL and COMB compared with CON and HEAT, whereas declines in T es-Mus within HEAT and COMB were substantially attenuated compared with CON and COOL. The decrease in T SK was most pronounced in COOL compared with CON, HEAT and COMB. During second-half, COMB and HEAT resulted in a larger decrease in PPO and MPO during the initial stages of the second-half when compared to CON. In addition, COOL resulted in an attenuated decrease in PPO and MPO compared to COMB in the latter stages of second-half., Conclusion: The maintenance of T es-Mus following half-time was detrimental to prolonged intermittent sprint performance in the heat, even when used together with cooling.

Purpose: The aim was to compare changes in peripheral and cerebral oxygenation, as well as metabolic and performance responses during conditions of blood flow restriction (BFR, bilateral vascular occlusion at 0% vs. 45% of resting pulse elimination pressure) and systemic hypoxia (~ 400 m, F I O 2 20.9% vs. ~ 3800 m normobaric hypoxia, F I O 2 13.1 ± 0.1%) during repeated sprint tests to exhaustion (RST) between leg- and arm-cycling exercises., Methods: Seven participants (26.6 ± 2.9 years old; 74.0 ± 13.1 kg; 1.76 ± 0.09 m) performed four sessions of RST (10-s maximal sprints with 20-s recovery until exhaustion) during both leg and arm cycling to measure power output and metabolic equivalents as well as oxygenation (near-infrared spectroscopy) of the muscle tissue and prefrontal cortex., Results: Mean power output was lower in arms than legs (316 ± 118 vs. 543 ± 127 W; p < 0.001) and there were no differences between conditions for a given limb. Arms demonstrated greater changes in concentration of deoxyhemoglobin (∆[HHb], - 9.1 ± 6.1 vs. - 6.5 ± 5.6 μm) and total hemoglobin concentration (∆[tHb], 15.0 ± 10.8 vs. 11.9 ± 7.9 μm), as well as the absolute maximum tissue saturation index (TSI, 62.0 ± 8.3 vs. 59.3 ± 8.1%) than legs, respectively (p < 0.001), demonstrating a greater capacity for oxygen extraction. Further, there were greater changes in tissue blood volume [tHb] during BFR only compared to all other conditions (p < 0.01 for all)., Conclusions: The combination of BFR and/or hypoxia led to increased changes in [HHb] and [tHb] likely due to greater vascular resistance, to which arms were more responsive than legs.

Aims: To determine the effects of high-intensity interval training (HIIT) following cardiac resynchronization therapy (CRT) implantation in patients with chronic heart failure (CHF), on noninvasive estimates of systolic ventricular function, exercise performance, severity of symptoms and quality of life., Methods: Cardiopulmonary exercise testing, resting transthoracic echocardiogram and health-related quality of life assessment were obtained before and at 6 months after CRT implantation in 37 patients with moderate-to-severe CHF. Patients were randomized after CRT to either a 24-week HIIT group (90-95% peak heart rate, 2 days per week) or to a usual care group (CON). Mixed design 2 × 2 repeated measures ANOVA were used to test for differences within and in-between groups., Results: Improvements in health-related quality of life (HIIT = 98.54%, CON = 123.47%), NYHA class (HIIT = 43.44%, CON = 38.30%) HR recovery at minute 1 (HIIT = 32.32%, CON = 42.94%), pulse pressure at peak effort (HIIT = 14.06%, CON = 9.52%, LVEF (HIIT = 42.17%, CON = 51.10%) and LV Mass (HIIT = 13.26%, CON = 11.88%) were similar in both groups (p > 0.05). Significant increases in CPET duration in the HIIT group (25.94%), and increases in peak VO 2 (HIIT = 8.64%, CON = 4.85%) and percent-predicted VO 2 (HIIT = 10.57%, CON = 4.26%) in both groups, were observed in the intention-to-treat analysis., Conclusion: Six months of HIIT in patients in CRT did not further improved indices of functional capacity and health-related quality of life, and LV structure and function, compared to CRT alone. However, HIIT led to further improvements in exercise performance. It remains unclear whether HIIT benefits patients in CRT to a similar degree as more conventional forms of exercise training previously shown to maximize benefits in CRT., Clinical Trial Registration: http://www.clinicaltrials.gov . Unique identifier: NCT02413151.

Background: CrossFit training is performed at high intensity and with limited or no recovery time between sets, being associated to increased injury risk. That is why this study determined injury epidemiology and risk factors for injury in Portuguese CrossFit practitioners., Methods: The sample included 270 CrossFit practitioners, aged 15 to 53, being 152 (56.3%) males. The measurement instrument was a questionnaire concerning characterization of the population, and aspects related to the modality and injuries., Results: Sixty-one (22.6%) individuals had an injury in the previous year, with a total of 80 injuries. There were 1.34 injuries per 1,000 hours of CrossFit training. The most common injuries were joint injuries (30.8%), and muscle injuries (23.1%), located in the shoulder (35.9%) and the lumbar spine (17.9%). The CrossFit practitioners who didn´t participate in competitions showed a 2.64 greater probability of having an injury (95% CI: 1.37-5.09; P=0.004) than those who did participate, and the CrossFit practitioners who trained twice or less a week showed a 3.24 greater probability of injury (95% CI: 1.78-5.89; P≤0.001) than those who trained three or more times., Conclusions: In conclusion, injuries proved to be common among CrossFit practitioners, especially those who train less and/or do not take part in competitions.

Background: Over the past decade, interest in high intensity interval training (HIIT) has increased considerably. The objective of this study was to determine injury incidence coinciding with increased popularity of HIIT and identify ways physicians can advise patients prior to participation., Methods: The National Electronic Injury Surveillance System (NEISS) was queried from 2007 through 2016 to estimate injury incidence related to exercises such as burpees, push-ups, and lunges and exercise equipment such as barbells, kettle bells, and boxes, which are representative of HIIT exercise programs. Injury incidences were calculated and compared between 2007-2011 and 2012-2016. Over the same time period, Google Trends was used to determine the popularity of HIIT., Results: There were an estimated 3,988,903 injuries, most often in males (58%) aged 20 to 39 years (39%). Most commonly, injuries were in the lower extremity (35.3%), trunk (28.5%), and upper extremity (19.6%). From 2012-2016 versus 2007-2011, there was a 144% increase in all injuries including a 159% increase in trunk injuries, a 137% increase in lower extremity injuries, and a 132% increase in upper extremity injuries. There was also a 127% increase in lower extremity strains and a 124% increase in upper extremity strains. Additionally, knee and ankle sprains increased 125%. These increases in injury incidence correlated with a 274% increase in HIIT interest., Conclusions: Given increases in injuries related to high-intensity workout programs, athletes should be educated on how to minimize preventable injuries. With particularly high rates of knee and ankle sprains and strains, neuromuscular training and pre-strengthening programs, which have been previously demonstrated to be effective among young athletes, may be particularly worthwhile in prospective participants. Physicians must be up to date with current fitness trends to best advise patients appropriately.