High-intensity Interval Training Sessions Research Articles

High-intensity Interval Training Reduces Symptom- And Disability-associated Inflammation Marker In Persons With Multiple Sclerosis

The inflammation marker neutrophil/lymphocyte ratio (NLR) receives increased attention in various diseases and can be influenced by acute exercise. In persons with multiple sclerosis (PwMS), the NLR is elevated and associated with disability and symptom severity. High-intensity interval training (HIIT) may induce larger benefits in PwMS than moderate continous training (MCT). PURPOSE: To explore acute and chronic effects of HIIT vs. MCT on NLR and cardiorespiratory fitness (chronic only) in PwMS. METHODS: An interims analysis of a randomized controlled trial comparing 3-weeks of HIIT vs. MCT during inpatient rehabilitation was conducted. 60 PwMS (mean age 49.7 yrs, EDSS 3-6) with relapsing remitting (n=38) and secondary progressive (n=22) subtype were included. The HIIT group performed 5×1.5 min intervals at 95–100% of their maximum heart rate (HRmax) with active breaks for 2 min in between. The MCT group exercised 24 min continuously at 65% HRmax. Both groups exercised 3×/week. An incremental exercise test with spirometry was conducted before and after the intervention. To assess chronic effects on NLR, blood samples were collected before (T0) the first exercise session and after the intervention period (T3) during resting conditions. To assess acute effects on NLR, samples were also collected immediately (T1) and 3 hours (h) (T2) after the first exercise session. NLR was calculated from blood panels. Baseline-adjusted ANCOVAs with Bonferroni post-hoc test were performed. RESULTS: Relative VO2peak increased in HIIT (mean difference (MD)=2.47 ml.kg-1.min-1, p<.001) and MCT (MD=1.5 ml.kg-1.min-1, p=.004), but no group differences were found. The increase in realtive peak power was larger in HIIT than in MCT (MD=.17 watts.kg-1, p=.031). NLR decreased after the intervention period (T3) within HIIT only (MD=-.27, p=.01). NLR was greater in HIIT 3 h after the first exercise session (T2) compared to MCT (MD=1.6, p=.05). CONCLUSION: Despite the short intervention period, cardiorepiratory fitness improved in both exercise modalities, whereas HIIT may induce greater enhancements. Only HIIT chronically reduced the NLR, thereby potentially contributing to symptom alleviation in PwMS. This chronic response might be due to repetitive inflammatory states after each HIIT session as reflected by the acute effects.

Extended Cardiac Rehabilitation Does Not Improve Exercise Adherence More Than Usual Care

PURPOSE: Exercise adherence is in general poor after cardiac rehabilitation (CR). In Norway, standard exercise-based CR typically offers 12 weeks of hospital-based supervised exercise at moderate or high intensity. The use of high-intensity interval training (HIT) in CR expands; however, it is still unclear how HIT affects exercise adherence. The purpose of this study was to assess the effect of an extended community-based or home-based CR program on long-term exercise adherence. METHODS: Between August 2014 and June 2017, 161 persons (27 women, age 62.3 (8.7) /134 men, age 60.1 (8.9)) were recruited. All had completed an HIT-based CR at St. Olav`s Hospital in Trondheim, Norway. They were randomized in a 1:1:1 ratio to an extended supervised community-based CR (ExCR) , a home-based CR (HCR) or a control group (CG). The extended CRs (ExCR and HCR) consisted of one HIT session and two additional sessions a week for eight weeks. The ExCR got a follow-up session every third month until one year after inclusion. The CG received usual care (standard advice for exercise and life style). Measurements were performed at baseline (T1), at 1 year (T2) and 2 years (T3) after inclusion. Primary outcome was peak oxygen uptake (VO2peak) at 2 years. Secondary outcome was achievement of current guidelines in regard of physical activity (PA) at moderate (MPA) and vigorous (VPA) intensity, measured with accelerometer. Data are analyzed with mixed linear model. RESULTS: Out of 161 participants, 144 (89%) completed the 2 year follow-up. VO2peak (ml/kg/min) was not significantly different between groups (p=0.777) at T1 (33.1 (7.7), 33.6 (8.5), 34.0 (7.2)), T2 (33.1 (7.9), 33.1 (8.4), 33.9 (7.4)) or T3 (30.9 (7.5), 32.2 (8.6) and 32.0 (7.3) for ExCR, HCR and CG, respectively). The decrease in VO2peak over time was significant from T2 to T3 (p=0.024). Daily average of minutes in MPA and VPA were not significantly different between groups (p=0.441 and p=0.557 respectively) at any time. There was a significant reduction from T1 to T2 in both MPA (107 (61) min to 100 (59) min, p=0.043) and VPA (14 (19) min to 11 (18) min, p=0.007). CONCLUSIONS: Extended cardiac rehabilitation did not enhance exercise adherence compared to usual care after a HIT-based CR program. Despite a decrease in VO2peak over two years, the amount of physical activity met the current guidelines.

Validity Of Wrist-worn Activity Trackers

The use of physical activity monitors has increased dramatically in the past decade. Wrist-worn activity monitors are often used to monitor heart rate (HR) for exercise intensity. Assessing the validity of these devices is essential for accurate exercise prescription and user safety. PURPOSE: The objective of this study was to assess the validity of three common wrist-worn physical activity monitors for measuring HR during three modes of exercise. METHODS: Twenty-one participants (seven males, fourteen females) completed the study. Inclusion criteria for participation were: ≥ 18 years of age, have no history of cardiovascular or chronic disease (assessed by PAR-Q+), and have the ability to run for 10 minutes at 6mph. HR data was recorded for three common physical activity monitors (AM1, AM2, AM3) during 10 minutes of walking at 3mph, running at 6mph, and High Intensity Interval Training (HIIT) session consisting of a body weight series of exercises. HR data was collected every minute and compared against gold standard chest strap HR monitor to assess validity. Descriptive statistics were performed for all variables. R2 values were calculated for each device and each mode of exercise. RESULTS: AM1 was the most accurate device with R2 of 0.733 for running and 0.678 for walking. AM2 data showed moderate R2 for running (0.54) and walking (0.44). AM3 HR data was unreliable. HITT condition was the least accurate for each monitor (R2 range 0.098-0.124). CONCLUSION: These results demonstrate that the accuracy of the devices for tracking HR increases with increasing intensity of steady-state activities. HR data during HIIT was unreliable possibly due to excessive movements. Assessed physical activity monitors in this study are not accurate for tracking HR during walking, running, and HIIT particularly if used for patient monitoring. The cheapest monitor (AM3) had a very weak correlation; consumers should consider more expensive monitors for more accurate HR readings during steady-state activities. More research needs to be done to further explore the accuracy of activity monitors for a wider range of modalities and intensities.

Prehabilitation With High Intensity Inverval Training Before Major Abdominal Surgery

PURPOSE: Improving cardiopulmonary reserve, or peak oxygen consumption (VO2peak) measured during cardiopulmonary exercise testing (CPET), may reduce complications after surgery. This feasibility study determined the effectiveness of a supervised, preoperative High Intensity Interval Training (HIIT) program in increasing VO2peak by 2ml/kg/min. Clinical outcomes were documented to determine the endpoint most sensitive to improved fitness. METHODS: In this prospective study, participants aged 50-85 undergoing major abdominal surgery were randomised to standard care or 14 sessions of HIIT over 4-6 weeks. HIIT sessions involved approximately thirty minutes of stationary cycling (5 warm-up, 20 interval training, 5 cool-down). Interval training alternated 1 minute of high and low intensity pedalling, with the goal of reaching 90% maximum heart rate during the session. Clinical outcomes included complications, postoperative morbidity survey, length of stay, and Short Form-36 quality of life questionnaire (SF-36). RESULTS: Of 63 participants, 46 completed both CPETs and 51 completed clinical follow-up. On per protocol analysis, mean VO2peak increased 14%, from 20.3-23.2ml/kg/min in the exercise group and 0.7%, from 21.8-22.0 ml/kg/min in the control group. Change in VO2peak was 2.87 vs. 0.14 ml/kg/min (p<.001). Exercisers increased peak work rate by 25 watts. Although there were no significant differences in the clinical outcomes, those most responsive to improved fitness with exercise were: the total number of postoperative complications (0.64 in exercisers vs. 1.16 in controls per patient, p=.07) and the physical component score of the SF-36 (p=.07), with the greatest difference six weeks after surgery indicating a quicker postoperative recovery. CONCLUSION: There was a significant improvement in VO2peak and peak work rate with preoperative HIIT. We also noted a trend towards fewer postoperative complications and a more rapid recovery after surgery. Preoperative HIIT results in a clinically important improvement in cardiopulmonary reserve for patients undergoing abdominal surgery.

Effects Of High Intensity Interval Training On Patient-reported Outcomes And Physical Function During Anthracycline Chemotherapy

PURPOSE: Breast cancer patients treated with anthracycline chemotherapy experience negative anthracycline-related side effects, including poor quality of life and impaired physical function. However, it is unclear whether high intensity interval training (HIIT) improves quality of life and physical function in breast cancer patients undergoing anthracycline-based chemotherapy. The purpose of this study was to examine the effects of HIIT on patient-reported outcomes and physical function in breast cancer patients with anthracycline-based chemotherapy. METHODS: Thirty breast cancer patients were recruited prior to initiating anthracycline-based chemotherapy and randomized into the HIIT group (n=15) or control (CON) group (n=15). The HIIT group attended the HIIT session for 3 days per week for 8 weeks. The CON group was asked to maintain their current level of physical activity and offered the same HIIT intervention after the 8-week study period. Patient-reported outcomes were assessed by the Functional Assessment of Cancer Therapy-Breast Cancer (FACT-B), Multidimensional Fatigue Inventory with 20 questions (MFI-20), andthe 15-item Five-Facet Mindfulness Questionnaire (FFMQ-15). Physical function was assessed using the timed up and go (TUG), 30-second sit-to-stand (30STS), Margaria-Kalamen stair climb test, and 6-minute walk test (6MWT). Repeated measures ANCOVA and paired t-tests were performed to assess changes in the outcome measures. RESULTS: Thirty breast cancer patients completed the 8-week study with 82.3% adherence to the intervention among the HIIT group. Post-intervention, significant improvements were found for the functional Margaria-Kalamen Power Test (-3.39%; P=0.013) and 6MWT (+11.6%; P=0.008) in the HIIT group compared baseline and to the CON group. No changes in patient-reported outcomes, TUG, and 30STS were found following the 8-week study period in both groups (P>0.05). CONCLUSIONS: HIIT may be an effective strategy to improve physical function and possibly maintain quality of life in breast cancer patients undergoing the anthracycline-based chemotherapy.

High-intensity Interval Training In Older Adults: A Scoping Review

High-intensity interval training (HIT) is an increasingly popular form of aerobic exercise which includes bouts of high-intensity exercise interspersed with periods of rest. The health benefits and risks as well as the optimal design of HIT are still unclear. Further, most of the research on the effects and benefits of HIT has been done in young and middle-aged adults and as such, the tolerability and effects in senior populations is less well-known. PURPOSE: To characterize HIT research that has been done in older adults including protocols, feasibility and safety as well as to identify gaps in the current knowledge. METHODS: Five databases were searched with variations of the search terms, “high-intensity interval training, high-intensity exercise” and “elderly, older adults.” These searches identified 3377 potential studies which were reviewed for inclusion. Studies were included if they were randomized controlled trials published in English in or after 2009, if the mean age of a treatment group was 65 years or older, and if the exercise protocols being tested were exclusively high-intensity or high-intensity interval training. RESULTS: Of 3377 papers identified in the initial search, 86 met the inclusion criteria. The HIT protocols used varied widely and ranged from a single session of HIT to a year-long program. These studies included both healthy and clinical populations. The greatest number of studies examined HIT in healthy subjects, followed by subjects with cardiac or vascular disease (heart failure, coronary artery disease, hypertension), metabolic dysfunction (Type-2 Diabetes Mellitus, obesity), and chronic obstructive pulmonary disease. Sample sizes ranged from 5 to 618 with 90% of studies including less than 70 subjects. The most common primary outcomes identified in the studies included changes in cardiorespiratory fitness as well as feasibility and safety of the protocols in the target populations. CONCLUSIONS: With a few exceptions, most studies had small sample sizes and many included non-clinical populations. Larger studies are needed to further evaluate the clinical effects of HIT in older adults. Additionally, there is much variety in the modes of exercise as well as the HIT protocols being used. Despite this, HIT was generally reported to be well-tolerated and safe in older populations.

Feasibility And Preliminary Efficacy Of High-intensity Interval Training During Neaodjuvant Chemoradiotherapy For Rectal Cancer

PURPOSE: To assess the feasibility, safety, and preliminary efficacy of a supervised high-intensity interval training (HIIT) program in rectal cancer patients undergoing 5-6 weeks of neoadjuvant chemoradiotherapy (NACRT). METHODS: Thirty-six rectal cancer patients scheduled to receive NACRT followed by surgery were randomized to either exercise training (n=18) or usual care (n=18) in the Exercise During and After Rectal Cancer Treatment (EXERT) Trial in Edmonton, Alberta. Patients in the exercise group were asked to complete 3 supervised HIIT sessions/week for the duration of NACRT. Feasibility was determined by eligibility rate, recruitment rate, follow-up rate and exercise adherence. Safety was assessed by tracking serious adverse events related to exercise. The primary efficacy outcome was cardiorespiratory fitness (VO2 peak) assessed immediately post-NACRT by a graded exercise test. Secondary efficacy outcomes included functional fitness assessed by the Senior’s Fitness Test. RESULTS: From June 2017 to August 2019, 205 rectal cancer patients were screened, 131 (64%) were eligible, and 36 (27%) were recruited. Follow-up fitness testing post-NACRT was completed in 75% (exercise n=14; control n=13). Reasons for missed fitness testing were medical issues. Median attendance for the supervised HIIT sessions during NACRT was 82%. No serious adverse events were observed, however, 2 patients in the exercise group experienced musculoskeletal events which resulted in 4 missed exercise sessions. Analyses of covariance showed no statistically significant or clinically meaningful difference between groups for the primary outcome of VO2 peak (adjusted between-group mean difference, 0.9 ml/kg/min; 95% CI, -1.6, 3.3; p = 0.47). The 8-foot up-and-go was significantly better in the exercise group post-NACRT (adjusted between group mean difference, -0.4 seconds; 95% CI, -0.7, 0.0, p = 0.031). No other significant group differences in functional fitness were observed. CONCLUSIONS: Supervised HIIT during NACRT for rectal cancer was feasible and safe. Further research is needed, however, to better understand the feasibility of completing fitness testing immediately following NACRT and whether HIIT can produce meaningful improvements in fitness in this challenging clinical setting.

Energetic System Contribution According Sprint Number In Tabata High Intensity Interval Training Protocol

PURPOSE: To analyze the contribution of energetic systems in Tabata’s high intensity-interval training (HIIT) protocol according sprint number METHODS: Sixteen physically active males attended to two experimental sessions. In the first one was performed an incremental test to identify the maximum oxygen uptake (VO2max) and power output (pVO2max). At the second visit, participants performed HIIT session composed by sprints lasting 20s at 170% of pVO2max followed by 10s rest until volitional fatigue. For the aerobic system estimative, difference between relative rest VO2 and its values during the activity was used. For the lactic system, the peak of blood lactate ([La-]) after the session was considered. The rapid phase of excess of post-exercise oxygen consumption (EPOCfast) was used for alactic system contribution. Participants were allocated in three groups, considering the number of sprints performed (G23 = 2 to 3, G45 = 4 to 5 or G67 = 6 to 7 sprints). Relative (%) energetic contribution were analyzed using two-way ANOVA (group x energetic system) RESULTS: Participants exhibited 24.9±6 years old, 1.67±2.7 cm, 55.6±8.7 kg and a VO2max = 55.6±8.7 mL/kg/min, with [La-] = 13.2±1.7 mmol/L and maximum heart rate = 184±9.3 bpm. For relative energetic contribution (% of aerobic, lactic and alactic respectively), G23 showed 32.3±11.9% (CI95%= 25.5 - 39.2), 24.2±3.9% (CI95%= 17.3 - 31.0) and 43.5±15.4% (CI95%= 36.6 - 50.3); G45 showed 46.3±7.9% (CI95%= 39.4 - 53.1), 22.7±3.9% (CI95%= 15.8 - 29.5) and 31.0±7.2% (CI95%= 24.2 - 37.9), and; G67 showed 60.2±2.3% (CI95%= 51.8 - 68.6); 19.2±2.1% (CI95%= 10.8 - 27.6) and 20.6±3.4% (CI95%= 12.2 - 28.9), with no differences between groups (F=0.0; p=1), differences between systems (F=33.30; p<.001) and statistical significant interactions (F=11.77; p<.001) CONCLUSIONS: Performing 2 to 3 sprints was found higher anaerobic contribution and performing 6 to 7 sprints, higher aerobic contribution in Tabata’s protocol. No participantes performed eight sprints.

Increasing Exercise Intensity: Teaching High-Intensity Interval Training to Individuals with Developmental Disabilities Using a Lottery Reinforcement System.

Rates of overweight and obesity are above 70% in typically developing adults in the United States, with higher rates observed in individuals diagnosed with developmental disability (DD). Lottery reinforcement systems have been validated as effective exercise interventions for individuals with DD. Although high-intensity interval training (HIIT) has demonstrated health benefits, it has not been studied using individuals within this population. The purpose of this study was to implement a lottery reinforcement system to systematically increase heart rate (HR) during 30-min HIIT sessions with 3 adults with DD. Results demonstrated increases in HR from below to within the prescribed range in all 3 participants. For 1 participant, weight decreased by 10.8 pounds during the 9-week program. Implications include that lottery systems increase exercise intensity with adults with DD, that HR during exercise can be reliably controlled using a lottery system, and that similar programs may result in health benefits.

Six high-intensity interval training sessions over 5 days increases maximal oxygen uptake, endurance capacity, and sub-maximal exercise fat oxidation as much as 6 high-intensity interval training sessions over 2 weeks

BackgroundHigh-intensity interval training (HIIT) induces similar or even superior adaptations compared to continuous endurance training. Indeed, just 6 HIIT sessions over 2 weeks significantly improves maximal oxygen uptake (VO2max), submaximal exercise fat oxidation, and endurance performance. Whether even faster adaptations can be achieved with HIIT is not known. Thus, we aimed to determine whether 2 sessions of HIIT per day, separated by 3 h, every other day for 5 days (double HIIT (HIIT-D), n = 15) could increase VO2max, submaximal exercise fat oxidation, and endurance capacity as effectively as 6 sessions of HIIT over 2 weeks (single HIIT (HIIT-S), n = 13). MethodsEach training session consisted of 10 × 60 s of cycling at 100% of VO2max interspersed with 75 s of low-intensity cycling at 60 watt (W). Pre- and post-training assessments included VO2max, time to exhaustion at ∼80% of VO2max, and 60-min cycling trials at ∼67% of VO2max. ResultsSimilar increases (p < 0.05) in VO2max (HIIT-D: 7.7% vs. HIIT-S: 6.0%, p > 0.05) and endurance capacity (HIIT-D: 80.1% vs. HIIT-S: 79.2%, p > 0.05) were observed. Submaximal exercise carbohydrate oxidation was reduced in the 2 groups after exercise training (HIIT-D: 9.2%, p = 0.014 vs. HIIT-S: 18.8%, p = 0.012) while submaximal exercise fat oxidation was significantly increased in HIIT-D (15.5%, p = 0.048) but not in HIIT-S (9.3%, p = 0.290). ConclusionSix HIIT sessions over 5 days was as effective in increasing VO2max and endurance capacity and was more effective in improving submaximal exercise fat oxidation than 6 HIIT sessions over 2 weeks.

Individualizing Training in Swimming: Evidence for Utilizing the Critical Speed and Critical Stroke Rate Concepts

To monitor physiological, technical, and performance responses to individualized high-intensity interval training (HIIT) prescribed using the critical speed (CS) and critical stroke rate (CSR) concepts in swimmers completing a reduced training volume program (≤30km·wk-1) for 15 weeks. Over the 15-week period, 12 highly trained swimmers (age 16 [1]y, height 179 [8]cm, weight 66 [8]kg) completed four 3-minute all-out tests to determine CS and the finite capacity to work above CS (D'), and four 200-m tests at CS to establish a CSR estimate. Combining CS and D', 2 HIIT sessions designed as 5 × 3-minute intervals depleting 60% of D' and 3 × 3.5-minute intervals depleting 80% of D' were prescribed once per week, respectively. An additional HIIT session was prescribed using CS and CSR as 10 × 150m or 200m at CS with 2 cycles per minute lower stroke rate than the CSR estimate. Additional monitored variables included peak speed, average speed for 150seconds (speed150s) and 180seconds (speed180s), competition performance and stroke length (SL), stroke count (SC), and stroke index (SI) adopted at CS. At the end of the intervention, swimmers demonstrated faster CS (mean change ± 90% confidence limits: +5.4 ± 1.6%), speed150s (+2.5 ± 0.9%), speed180s (+3.0 ± 0.9%), and higher stroke rate (+6.4 ± 3.0%) and stroke index (+4.2 ± 3.6%). D' was reduced (-25.2 ± 7.5%), whereas peak speed, SL, and SC changed only trivially. The change in the swimmers' personal best times in the first and second main event was -1.2 ± 1.3% and -1.6 ± 0.9%, respectively. HIIT prescribed based on the CS and CSR concepts was associated with improvements in several physiological, technical, and performance parameters in highly trained swimmers while utilizing time- and resource-efficient approach. This was achieved despite a ≥25% reduction in training volume.

A Comparison of Heart Rate Training Load and Perceptual Effort Between Masters and Young Cyclists

Due to age-related changes in the psychobiological state of masters athletes, this brief report aimed to compare training load responses using heart rate (HR) and ratings of perceived exertion (RPE) during standardized training sessions between masters and young cyclists. Masters (n = 10; 55.6 [5.0]y) and young (n = 8; 25.9 [3.0]y) cyclists performed separate endurance and high-intensity interval training sessions. Endurance intensity was set at 95% of ventilatory threshold 2 for 1hour. High-intensity interval training consisted of 6 × 30-second intervals at 175% peak power output with 4.5-minute rest between intervals. HR was monitored continuously and RPE collected at standardized time periods during each session. Banister training impulse and summated-HR-zones training loads were also calculated. Despite a significantly lower mean HR in masters cyclists during endurance (P = .04; d = 1.06 [±0.8], moderate) and high-intensity interval training (P = .01; d = 1.34 [±0.8], large), no significant differences were noted (P > .05) when responses were determined relative to maximum HR or converted to training impulse and summated-HR-zone loads. Furthermore, no interaction or between-group differences were evident for RPE across either session (P > .05). HR and RPE values were comparable between masters and young cyclists when relative HR responses and HR training load models are used. This finding suggests HR and RPE methods used to monitor or prescribe training load can be used interchangeably between masters and young athletes irrespective of chronological age.

Fatigue Induced Changes in Muscle Strength and Gait Following Two Different Intensity, Energy Expenditure Matched Runs.

PurposeTo investigate changes in hip and knee strength, kinematics, and running variability following two energy expenditure matched training runs; a medium intensity continuous run (MICR) and a high intensity interval training session (HIIT).MethodsTwenty (10 Females, 10 Males) healthy master class runners were recruited. Each participant completed the HIIT consisting of six repetitions of 800 m with a 1:1 work: rest ratio. The MICR duration was set to match energy expenditure of the HIIT session. Hip and knee muscular strength were examined pre and post both HIIT and MICR. Kinematics and running variability for hip and knee, along with spatiotemporal parameters were assessed at start and end of each run-type. Changes in variables were examined using both 2 × 2 ANOVAs with repeated measures and on an individual level when the change in a variable exceeded the minimum detectable change (MDC).ResultsAll strength measures exhibited significant reductions at the hip and knee (P < 0.05) with time for both run-types; 12% following HIIT, 10.6% post MICR. Hip frontal plane kinematics increased post run for both maximum angle (P < 0.001) and range of motion (P = 0.003). Runners exhibited increased running variability for nearly all variables, with the HIIT having a greater effect. Individual assessment revealed that not all runners were effected post run and that following HIIT more runners had reduced muscular strength, altered kinematics and increased running variability.ConclusionRunners exhibited fatigue induced changes following typical training runs, which could potentially present risk of injury development. Group and individual assessment revealed different findings where the use of MDC is recommended over that of P-values.

Short-term and long-term effect of a high-intensity pulmonary rehabilitation programme in obese patients with asthma: a randomised controlled trial.

To determine the short-term and long-term effects of a high intensity pulmonary rehabilitation programme on asthma control, body composition, lung function and exercise capacity in obese asthma patients. Patients with obesity (body mass index (BMI)≥30 kg·m-2) and suboptimal controlled asthma (Asthma Control Questionnaire (ACQ)≥0.75) were randomly assigned to a 3-month pulmonary rehabilitation programme (PR only), pulmonary rehabilitation programme with the use of an internet based self-management support programme (PR+SMS) or usual care. The pulmonary rehabilitation programme included high-intensity interval training, nutritional intervention and psychological group sessions. Patients in the usual care group were advised to lose weight and to exercise. The primary outcome was the difference of change of ACQ between PR only and PR+SMS after 3 months. Total follow-up was 12 months. 34 patients were included in the study (14 PR only, nine PR+SMS, 11 control). Compared with patients in usual care, patients in the PR only group had a significant reduction in BMI and significant improvements in asthma control, exercise capacity and aerobic capacity after 3 months. These improvements persisted during 12 months of follow-up. No difference in ACQ between PR+SMS and PR only groups was observed. However, users of the SMS programme had a significantly lower BMI after 12 months compared with subjects in the PR only group. A high-intensity pulmonary rehabilitation programme provides sustained improvements in asthma control, body composition and exercise capacity in obese asthmatics that are not optimally controlled and, therefore, should be considered in the treatment of these patients.

Optimizing Interval Training Through Power-Output Variation Within the Work Intervals.

Maximal oxygen uptake (V˙O2max) is a key determinant of endurance performance. Therefore, devising high-intensity interval training (HIIT) that maximizes stress of the oxygen-transport and -utilization systems may be important to stimulate further adaptation in athletes. The authors compared physiological and perceptual responses elicited by work intervals matched for duration and mean power output but differing in power-output distribution. Fourteen cyclists (V˙O2max 69.2 [6.6]mL·kg-1·min-1) completed 3 laboratory visits for a performance assessment and 2 HIIT sessions using either varied-intensity or constant-intensity work intervals. Cyclists spent more time at >90%V˙O2max during HIIT with varied-intensity work intervals (410 [207] vs 286 [162]s, P = .02), but there were no differences between sessions in heart-rate- or perceptual-based training-load metrics (all P ≥ .1). When considering individual work intervals, minute ventilation (V˙E) was higher in the varied-intensity mode (F = 8.42, P = .01), but not respiratory frequency, tidal volume, blood lactate concentration [La], ratings of perceived exertion, or cadence (all F ≤ 3.50, ≥ .08). Absolute changes (Δ) between HIIT sessions were calculated per work interval, and Δ total oxygen uptake was moderately associated with ΔV˙E (r = .36, P = .002). In comparison with an HIIT session with constant-intensity work intervals, well-trained cyclists sustain higher fractions of V˙O2max when work intervals involved power-output variations. This effect is partially mediated by an increased oxygen cost of hyperpnea and not associated with a higher [La], perceived exertion, or training-load metrics.

Acute Vascular Responses to All‐Extremity Aerobic Exercise

Endothelial function and central arterial stiffness are independent predictors of future cardiovascular events. High‐intensity interval training (HIIT) is a popular and oftentimes superior exercise strategy for decreasing cardiovascular disease risk than moderate‐intensity continuous training (MICT). We have recently adapted HIIT on a non‐weight‐bearing all‐extremity ergometer to reduce impact on the joints and involve muscles in the whole body to activate a larger amount of muscle mass than in lower‐extremity HIIT. However, the acute vascular responses to all‐extremity HIIT and MICT remain unexplored and may be important for optimizing exercise prescription. Therefore, the purpose of this study was to investigate the acute effects of all‐extremity HIIT and MICT on endothelial function, central arterial stiffness and hemodynamics. Sixteen young men (21±1 years of age, means±SE) who were free of clinical disease and did not use tobacco products or medications participated in this study. Vascular measures were assessed at pre‐exercise, at the end of a single session of HIIT and MICT and following recovery. HIIT and MICT were matched for caloric expenditure and were performed on an all‐extremity non‐weight‐bearing ergometer, at least one week apart. HIIT consisted of 4×4‐min intervals at 90% peak heart rate (HRpeak) interspersed by 3‐min intervals at 70% HRpeak for a total of 40 min. MICT consisted of 47 min at 70% HRpeak. Endothelial function was assessed using brachial artery flow‐mediated dilation (FMD) via high resolution ultrasonography in response to 5 min forearm blood flow occlusion. Arterial stiffness (carotid to femoral pulse wave velocity; cfPWV), aortic wave reflection (augmentation index normalized at heart rate 75; AIx75) and aortic systolic and diastolic blood pressure (aoSBP and aoDBP) were assessed using a validated cuff‐based device. HIIT did not result in significant changes in FMD (P=0.08), cfPWV (P=0.3), aoSBP (P=0.1) or aoDBP (P=0.2) within one hour from exercise cessation. AIx75 and heart rate were increased at the end of HIIT and remained elevated following recovery (P≤0.002 vs. pre‐exercise). In response to MICT, FMD remained unchanged (P=0.1). However, cfPWV decreased at the end of MICT (P=0.003) and returned to the pre‐exercise level following recovery (P=0.5). AIx75 increased at the end of MICT (P&lt;0.0001) and returned to the pre‐exercise level following recovery (P=0.3). aoSBP decreased following recovery compared with end of MICT (P=0.04), but was not different than the pre‐exercise level (P=0.3). aoDBP did not significantly change in response to MICT (P=0.09). In conclusion, all‐extremity HIIT and MICT did not attenuate endothelial function or result in adverse changes in aortic blood pressure. MICT, but not HIIT, slightly reduced central arterial stiffness. These findings may have important implications for exercise prescription.

High-intensity interval training increases myocardial levels of Klotho and protects the heart against ischaemia-reperfusion injury.

What is the central question of this study? Can short-term high-intensity interval training (HIIT) contribute to the reduction of ischaemia-reperfusion (IR) injury by enhancing the levels of Klotho and its related axes, including myocardial TRPC6 expression, and antioxidant defence as novel possible mechanisms of exercise-induced cadioprotection (EICP) against IR injury? What is the main finding and its importance? The increase of plasma and myocardial levels of Klotho as a result of preconditioning with HIIT and prevention of a significant reduction of Klotho during IR injury can promote cardioprotection and reduce damage by attenuating myocardial TRPC6 expression and increasing antioxidant defence. The present findings may provide a new mechanism in EICP and IR injury, and provide the knowledge to develop preventive and therapeutic approaches. Cardiovascular disease, especially coronary artery disease, remains a major cause of morbidity and mortality in the world, and ischaemia-reperfusion (IR) insult is the main pathological cause leading to death. Exercise training is associated with a reduced risk of cardiovascular disease and the development of cardioprotection against IR injury. Therefore, the purpose of this study was to investigate the effect of preconditioning with high-intensity interval training (HIIT) on myocardial and plasma levels of Klotho and its related axes as novel mechanisms of exercise-induced cardioprotection against IR injury. Seventy male Wistar rats were randomly divided into five groups of control, HIIT, sham, IR and HIIT group that underwent IR injury (H-IR). The training group performed five sessions of HIIT on the treadmill. The cardiac IR injury was induced by ligation of the left anterior descending coronary artery for 30min followed by 24h reperfusion. Infarct size and histopathological assessment of cardiac tissues were determined through Evans Blue-triphenyltetrazolium chloride and haematoxylin-eosin staining, respectively. We investigated lipid peroxidation and markers of cardiac injury, antioxidant enzymes and the plasma levels of Klotho using enzyme-linked immunosorbent assays. Also, myocardial levels of Klotho and TRPC6 expression were determined by western blot assays. The results demonstrated a significant increase in myocardial and plasma levels of Klotho following HIIT and a significant decrease during IR injury. Myocardial TRPC6 channel expression increased following IR. HIIT also prevented a significant reduction of Klotho during IR and consequently reduced the expression of the TRPC6 channel in the H-IR group compared with the IR group. Furthermore, HIIT decreased the infarct size, cardiac injury, lipid peroxidation, lactate dehydrogenase, creatine kinase myocardial band and cardiac troponin-I, and improved total antioxidant capacity and catalase, superoxide dismutase and glutathione peroxidase activities following IR injury. The findings of the present study suggest that HIIT improves cardioprotection against IR injury and reduces cardiac damages through an increase in myocardial and plasma levels of Klotho and its related axes (TRPC6 and antioxidant defence). These findings can help to develop preventive and therapeutic approaches.

Effect of fish oil supplementation combined with high-intensity interval training in newly diagnosed non-obese type 2 diabetes: a randomized controlled trial.

The additive effect of high-intensity interval training to fish oil supplementation on newly diagnosed type 2 diabetes is unknown. 173 newly diagnosed type 2 diabetes patients were randomly assigned into the control group (received corn oil), fish oil group (eicosapentaenoic acid, EPA:docosahexaenoic acid, DHA=3:2, total 2.0g/day), and the fish oil+high-intensity interval training group. Three instructed high-intensity interval training sessions (Monday, Wednesday, and Friday; 10×60-s cycling bouts) were performed for 3 months. Glycaemic control was assayed by serum haemoglobin A1c, fast glucose, fast insulin, and adiponectin. Homeostatic model assessment of insulin resistance was utilized to determine the homeostasis of pancreatic function. Fat mass, triglycerides, total cholesterol, low-density lipoproteins, and high-density lipoproteins were measured to indicate cardiovascular risk. Within and between groups analysis were performed with linear mixed-effects modeling (95% CIs and p values). When compared with fish oil, fish oil+high-intensity interval training intervention has significant additive beneficial effects on haemoglobin A1c (p<0.01), fast glucose (p<0.001), homeostatic model assessment of insulin resistance (p<0.05), adiponectin (p<0.05), fat mass (p<0.01), and total cholesterol (p<0.01), but not on fast insulin level to newly diagnosed non-obese type 2 diabetes. High-intensity interval training has an additive effect on fish oil supplementation on glycaemic control, insulin resistance, cardiovascular risk, and fat mass, which indicates the potential necessity of combining high-intensity interval training with fish oil.

Locomotor training intensity after stroke: Effects of interval type and mode

ABSTRACT Background and Objectives: High-intensity interval training (HIIT) is a promising strategy for improving gait and fitness after stroke, but optimal parameters remain unknown. We tested the effects of short vs long interval type and over-ground vs treadmill mode on training intensity. Methods: Using a repeated measures design, 10 participants with chronic hemiparesis performed 12 HIIT sessions over 4 weeks, alternating between short and long-interval HIIT sessions. Both protocols included 10 minutes of over-ground HIIT, 20 minutes of treadmill HIIT and another 10 minutes over-ground. Short-interval HIIT involved 30 second bursts at maximum safe speed and 30–60 second rest periods. Long-interval HIIT involved 4-minute bursts at ~90% of peak heart rate (HRpeak) and 3-minute recovery periods at ~70% HRpeak. Results: Compared with long-interval HIIT, short-interval HIIT had significantly faster mean overground speeds (0.75 vs 0.67 m/s) and treadmill speeds (0.90 vs 0.51 m/s), with similar mean treadmill HR (82.9 vs 81.8%HRpeak) and session perceived exertion (16.3 vs 16.3), but lower overground HR (78.4 vs 81.1%HRpeak) and session step counts (1481 vs 1672). For short-interval HIIT, training speeds and HR were significantly higher on the treadmill vs. overground. For long-interval HIIT, the treadmill elicited HR similar to overground training at significantly slower speeds. Conclusions: Both short and long-interval HIIT elicit high intensities but emphasize different dosing parameters. From these preliminary findings and previous studies, we hypothesize that overground and treadmill short-interval HIIT could be optimal for improving gait speed and overground long-interval HIIT could be optimal for improving gait endurance.

Acute effect of juçara juice (Euterpe edulis Martius) on oxidative stress biomarkers and fatigue in a high-intensity interval training session: A single-blind cross-over randomized study

Abstract This study aimed to evaluate the effects of jucara juice on oxidative stress biomarkers and fatigue in a high-intensity interval training (HIIT) session. Fifteen physically active men were assigned to drink 250 mL of jucara juice or water (control) 1 h before exercise. Blood samples were collected 1 h prior to exercise, immediately post exercise, and 1 h post exercise. From the relative average changes, a decrease in oxidative stress index was observed immediately post exercise (P = 0.020) and an increase in reduced glutathione 1 h post exercise (P = 0.044) in the jucara juice intake group in relation to the control. Jucara juice intake also promoted increases in plasma total phenols (P = 0.020), and uric acid (P = 0.001) over time. Moreover, individuals who consumed jucara juice presented lower fatigue compared to the control (P