Phase 1 randomized trial of inpatient high-intensity interval training after major surgery.

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.

High-intensity interval training in patients with intermittent claudication.

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.

Mecanismos de adaptação do coração em atletas de elite do sexo feminino: comparação com indivíduos sadios e tempo de treinamento / Heart adaptation mechanisms in elite female athletes: comparison with healthy individuals and time of training

Fundamento: O exercício intenso e continuado em atletas provoca fenótipos de remodelamento adaptativo, cujos parâmetros podem ser avaliados pela ecocardiografia convencional, e de deformação miocárdica. Assim, foi comparado o remodelamento miocárdico em atletas do sexo feminino (grupo atletas) com mulheres sedentárias da mesma faixa etária (grupo-controle) e entre atletas com maior e menor tempo de treinamento. Métodos: Foram selecionadas 57 futebolistas femininas (grupo atletas) e 25 mulheres sadias sedentárias (grupocontrole). As atletas foram divididas em dois grupos: grupo principal, com 32 atletas, e grupo sub-17, com 25 atletas. Foram determinadas, através de ecocardiografia, as dimensões, a função sistólica e diastólica das câmaras cardíacas e a deformação miocárdica (strain longitudinal, circunferencial, radial e mecânica rotacional), utilizando a estatística Z com significância de p < 0,05. Resultados: A idade dos grupos atletas, controle, principal e sub-17 foi de 22,1±6,3; 21,2±5,0; 26,5±5,1; e 16,5±0,6, respectivamente. O peso, o índice de massa corporal e a frequência cardíaca foram menores no grupo atletas. A espessura das paredes, o índice de massa do ventrículo esquerdo (VE), o volume do átrio esquerdo (AE), a fração de ejeção e as dimensões do ventrículo direito (VD) foram maiores no grupo atletas, mas dentro de valores normais. A deformação miocárdica mostrou diminuição do strain radial, da rotação basal, da rotação apical e do twist, sugerindo mecanismo de reserva contrátil. Esses parâmetros foram menores no grupo principal, que também apresentava maior espessura das paredes, maior volume do AE e maior tamanho do VD, sugerindo que o aumento da reserva contrátil se relaciona com maior tempo de treinamento. Conclusões: As atletas do sexo feminino com treinamento intenso de longa duração apresentam remodelamento adaptativo das câmaras cardíacas e aumento da reserva contrátil observada em repouso, com esses parâmetros mais acentuados nas atletas com maior tempo de treinamento.(AU)

Background: Intense continuous exercise provokes adaptive remodeling phenotypes in athletes, the parameters of which can be evaluated through conventional echocardiography and myocardial deformation. We compared myocardial remodeling in female athletes (athlete group) with sedentary women of the same age range (control group) and between older and younger athletes. Methods: A total of 57 female soccer players and 25 healthy sedentary women were selected. The athlete group was subdivided into a main group and those under 17 years of age (< 17 group). The dimensions and systolic and diastolic function of the cardiac chambers and myocardial deformation (longitudinal and circumferential, as well as radial strain and rotational mechanics) was determined through echocardiography, using the Z statistic with a significance level of p< 0.05. Results: The mean age of the athlete, control, main, and < 17 groups was 22.1 (SD, 6.3); 21.2 (SD, 5.0); 26.5 (SD, 5.1); 16.5 (SD, 0.6) years, respectively. Weight, body mass index and heart rate were lower in the athlete group. Wall thickness, left ventricular mass index, left atrial (LA) volume, ejection fraction, and right ventricular dimensions were higher in athlete group, but remained within normal ranges. Regarding myocardial deformation, there was decreased radial strain, basal rotation, apical rotation, and twisting in the athlete group, suggesting a contractile reserve mechanism. These parameters were lesser in the main athlete group, who also had greater wall thickness, greater volume in the left atrium (LA) and larger size in the right ventricle (RV), suggesting that increased contractile reserve is related to longer time spent in the sport. Conclusions: In female athletes who had undergone intense long-term training, we observed adaptive remodeling of the cardiac chambers and increased contractile reserve (at rest), and these changes were more pronounced in those with longer involvement in the sport.(AU)

Glycemic response to acute high-intensity interval versus moderate-intensity continuous exercise during pregnancy.

The present study investigated the glycemic response to an acute high-intensity interval training (HIIT) session (10 one-minute intervals ≥90% HRmax interspersed with one-minute of active recovery) versus a moderate-intensity continuous training (MICT) session (30 min at 64%-76% HRmax ) 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% HRmax ) compared with MICT (74 ± 4% HRmax ; p < 0.001) and participants achieved a peak heart rate of 92 ± 3% during HIIT (range 85%-97% HRmax ) 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.

Acute fetal response to high-intensity interval training in the second and third trimesters of pregnancy.

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.

Vitamin D, Its Role in Recovery after Muscular Damage Following Exercise.

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.

High-intensity interval running impairs subsequent upper limb strength performance.

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.

Effect of exercise training on heart rate variability in type 2 diabetes mellitus patients: A systematic review and meta-analysis.

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.

Effects of high-intensity interval training in more or less active mice on biomechanical, biophysical and biochemical bone parameters.

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 cm2 and 4800 cm2 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.

Hepcidin response to three consecutive days of endurance training in hypoxia.

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 (FiO2): 14.5%) or normoxia (FiO2: 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]O2max) with 2 min of active rest at 30% of [Formula: see text]O2max] followed by 30 min of continuous exercise at 60% of [Formula: see text]O2max. 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.

HIIT is superior than MICT on cardiometabolic health during training and detraining.

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.

Acute leucocyte, muscle damage, and stress marker responses to high-intensity functional training.

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.

Impact of a 4-Week Intensified Endurance Training Intervention on Markers of Relative Energy Deficiency in Sport (RED-S) and Performance Among Well-Trained Male Cyclists.

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 (VO2peak): 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], VO2peak [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 (T3) [4.8%, p = 0.008], absolute RMR [3.0%, p = 0.010], relative RMR [2.6%, p = 0.013], and RMRratio [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 T3, 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.

Short-term and Long-term Feasibility, Safety, and Efficacy of High-Intensity Interval Training in Cardiac Rehabilitation: The FITR Heart Study Randomized Clinical Trial.

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.

A Big HIIT: A Fracture Dislocation of the Hip in a Young Man Participating in Extreme Conditioning Exercise: A Case Report.

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.

The impact of high-intensity interval training exercise on breast cancer survivors: a pilot study to explore fitness, cardiac regulation and biomarkers of the stress systems.

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 (VO2peak), 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 VO2peak 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 .

Acute effects of high-intensity interval training session and endurance exercise on pulmonary function and cardiorespiratory coupling.

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 (LFHRV ) and high-frequency (HFHRV ) components of HRV were increased and decreased, respectively, after HIIT. The increase in LFHRV 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.

Left atrial mechanics and aortic stiffness following high intensity interval training: a randomised controlled study.

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 cm2 dyn-1 103, 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 R2 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.

Thromboembolic events after high-intensity training during cisplatin-based chemotherapy for testicular cancer: Case reports and review of the literature.

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.