Cerebrovascular responses to graded exercise in young healthy males and females.

Although systemic sex-specific differences in cardiovascular responses to exercise are well established, the comparison of sex-specific cerebrovascular responses to exercise has gone under-investigated especially, during high intensity exercise. Therefore, our purpose was to compare cerebrovascular responses in males and females throughout a graded exercise test (GXT). Twenty-six participants (13 Females and 13 Males, 24 ± 4 yrs.) completed a GXT on a recumbent cycle ergometer consisting of 3-min stages. Each sex completed 50W, 75W, 100W stages. Thereafter, power output increased 30W/stage for females and 40W/stage for males until participants were unable to maintain 60-80 RPM. The final stage completed by the participant was considered maximum workload(Wmax ). Respiratory gases (End-tidal CO2 , EtCO2 ), middle cerebral artery blood velocity (MCAv), heart rate (HR), non-invasive mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) were continuously recorded on a breath-by-breath or beat-by-beat basis. Cerebral perfusion pressure, CPP = MAP (0. 7,355 distance from heart-level to doppler probe) and cerebral vascular conductance index, CVCi = MCAv/CPP 100mmHg were calculated. The change from baseline (Δ) in MCAv was similar between the sexes during the GXT (p = .091, ωp2  = 0.05). However, ΔCPP (p < .001, ωp2  = 0.25) was greater in males at intensities ≥ 80% Wmax and ΔCVCi (p = .005, ωp2  = 0.15) was greater in females at 100% Wmax . Δ End-tidal CO2 (ΔEtCO2 ) was not different between the sexes during exercise (p = .606, ωp2  = -0.03). These data suggest there are sex-specific differences in cerebrovascular control, and these differences may only be identifiable at high and severe intensity exercise.

High-Intensity Interval Circuit Training Versus Moderate-Intensity Continuous Training on Cardiorespiratory Fitness in Middle-Aged and Older Women: A Randomized Controlled Trial.

High-intensity interval training (HIIT) has similar or better effects than moderate-intensity continuous training (MICT) in increasing peak oxygen consumption (VO2max), however, it has not been studied when HIIT is applied in a circuit (HIICT). The aim of this study was to compare the effects of a HIICT versus MICT on VO2max estimated (VO2max-ES), heart rate (HR) and blood pressure (BP) of middle-aged and older women. A quasi-experimental randomized controlled trial was used. Fifty-four women (67.8 ± 6.2 years) were randomized to either HIICT (n = 18), MICT (n = 18) or non-exercise control group (CG; n = 18) for 18 weeks. Participants in HIICT and MICT trained two days/week (one hour/session). Forty-one participants were assessed (HIICT; n = 17, MICT; n = 12, CG; n = 12). Five adverse events were reported. Cardiorespiratory fitness, HR and BP were measured. The tests were performed before and after the exercise intervention programs. VO2max-ES showed significant training x group interaction, in which HIICT and MICT were statistically superior to CG. Moreover, HIICT and MICT were statistically better than CG in the diastolic blood pressure after exercise (DBPex) interaction. For the systolic blood pressure after exercise (SBPex), HIICT was statistically better than CG. In conclusion, both HIICT and MICT generated adaptations in VO2max-ES and DBPex. Furthermore, only HIICT generated positive effects on the SBPex. Therefore, both training methods can be considered for use in exercise programs involving middle-aged and older women.

The Impact of Sprint Interval Training Frequency on Blood Glucose Control and Physical Function of Older Adults.

Exercise is a powerful tool for improving health in older adults, but the minimum frequency required is not known. This study sought to determine the effect of training frequency of sprint interval training (SIT) on health and physical function in older adults. Thirty-four (13 males and 21 females) older adults (age 65 ± 4 years) were recruited. Participants were allocated to a control group (CON n = 12) or a once- (n = 11) or twice- (n = 11) weekly sprint interval training (SIT) groups. The control group maintained daily activities; the SIT groups performed 8 weeks of once- or twice-weekly training sessions consisting of 6 s sprints. Metabolic health (oral glucose tolerance test), aerobic capacity (walk test) and physical function (get up and go test, sit to stand test) were determined before and after training. Following training, there were significant improvements in blood glucose control, physical function and aerobic capacity in both training groups compared to control, with changes larger than the smallest worthwhile change. There was a small to moderate effect for blood glucose (d = 0.43-0.80) and physical function (d = 0.43-0.69) and a trivial effect for aerobic capacity (d = 0.01) between the two training frequencies. Once a week training SIT is sufficient to produce health benefits. Therefore, the minimum time and frequency of exercise required is much lower than currently recommended.

Guidelines for the delivery and monitoring of high intensity interval training in clinical populations.

High intensity interval training (HIIT) is now recognized in international clinical-based exercise guidelines as an appropriate and beneficial adjunct to moderate intensity continuous training. HIIT involves alternating periods of high intensity aerobic exercise with light recovery exercise or no exercise, allowing for greater physiological stimulus and adaptation than moderate intensity continuous training (MICT) for cardiorespiratory fitness and other cardiometabolic processes. However, there is no universal criteria or framework for the prescription and monitoring of HIIT in clinical populations, and safety concerns remain a common barrier for implementing HIIT as standard care. Historically, exercise intensity has been prescribed using heart rate (HR) targets derived from either a predicted maximal HR (HRmax) or from an attempt to objectively measure HRmax. However, using this approach alone has a number of limitations. Here we provide guidelines to improve the delivery of HIIT in cardiometabolic populations using 1) a framework for HIIT prescription using a combination of objective and subjective measures of exercise intensity, and 2) clinical considerations for assessment and monitoring to maximize patient safety. The framework involves an individualized step-by-step process to calculate, validate, and calibrate HR target zones for HIIT training to allow for appropriate workload prescription and progression. We strongly recommend this framework be used in future clinical trials investigating HIIT.

High-Intensity Interval Training in Heart Transplant Recipients: A Systematic Review with Meta-Analysis.

Heart transplantation (HTx) is considered an efficient and gold-standard procedure for patients with end-stage heart failure. After surgery, patients have lower aerobic power (VO2max) and compensatory hemodynamic responses. The aim of the present study was to assess through a systematic review with meta-analysis whether high-intensity interval training (HIIT) can provide benefits for those parameters. This is a systematic review with meta-analysis, which searched the databases and data portals PubMed, Web of Science, Scopus, Science Direct and Wiley until December 2016 (pairs). The following terms and descriptors were used: "heart recipient" OR "heart transplant recipient" OR "heart transplant" OR "cardiac transplant" OR "heart graft". Descriptors via DeCS and Mesh were: "heart transplantation'' OR "cardiac transplantation". The words used in combination (AND) were: "exercise training" OR "interval training" OR "high intensity interval training" OR "high intensity training" OR "anaerobic training" OR "intermittent training" OR "sprint training". The initial search identified 1064 studies. Then, only those studies assessing the influence of HIIT on the post-HTx period were added, resulting in three studies analyzed. The significance level adopted was 0.05. Heart transplant recipients showed significant improvement in VO2peak, heart rate and peak blood pressure in 8 to 12 weeks of intervention.

High-Intensity Interval Training in Heart Transplant Recipients: A Systematic Review with Meta-Analysis / Treinamento Intervalado de Alta Intensidade em Transplantados de Coração: Uma Revisão Sistemática com Meta-Análise

Abstract Heart transplantation (HTx) is considered an efficient and gold-standard procedure for patients with end-stage heart failure. After surgery, patients have lower aerobic power (VO2max) and compensatory hemodynamic responses. The aim of the present study was to assess through a systematic review with meta-analysis whether high-intensity interval training (HIIT) can provide benefits for those parameters. This is a systematic review with meta-analysis, which searched the databases and data portals PubMed, Web of Science, Scopus, Science Direct and Wiley until December 2016 (pairs). The following terms and descriptors were used: "heart recipient" OR "heart transplant recipient" OR "heart transplant" OR "cardiac transplant" OR "heart graft". Descriptors via DeCS and Mesh were: "heart transplantation'' OR "cardiac transplantation". The words used in combination (AND) were: "exercise training" OR "interval training" OR "high intensity interval training" OR "high intensity training" OR "anaerobic training" OR "intermittent training" OR "sprint training". The initial search identified 1064 studies. Then, only those studies assessing the influence of HIIT on the post-HTx period were added, resulting in three studies analyzed. The significance level adopted was 0.05. Heart transplant recipients showed significant improvement in VO2peak, heart rate and peak blood pressure in 8 to 12 weeks of intervention.

Resumo O transplante de coração é considerado procedimento eficiente e padrão ouro para pacientes com quadro de insuficiência cardíaca terminal. Verifica-se que após o procedimento cirúrgico os pacientes apresentam menor valor de potência aeróbia (VO2máx) e respostas hemodinâmicas descompensadas. O objetivo do presente estudo foi de verificar por meio de uma revisão sistemática com meta-análise se o treinamento intervalado de alta intensidade é capaz de proporcionar benefícios a tais capacidades. Trata-se de uma revisão sistemática com meta-análise, que realizou buscas em pares nas bases e portais de dados PubMed, Web of Science, Scopus, Science Direct e Wiley até dezembro de 2016. Para busca dos artigos utilizaram-se os termos e descritores: "heart recipient" OR "heart transplant recipient" OR "heart transplant" OR "cardiac transplant" OR "heart graft". Os descritores pelo DeCS e Mesh foram: "heart transplantation'' OR "cardiac transplantation". As palavras utilizadas em combinação (AND) foram "exercise training" OR "interval training" OR "high intensity interval training" OR "high intensity training" OR "anaerobic training" OR "intermittent training" OR "sprint training". A busca inicial identificou 1064 estudos. Em seguida, apenas os estudos que analisaram a influência do treinamento intervalado de alta intensidade no período pós transplante foram adicionados, sendo, assim, três estudos analisados. O nível adotado nas análises estatísticas para determinar significância foi de 0,05. Verificou-se que, entre 8 e 12 semanas de intervenção, os pacientes transplantados de coração apresentaram melhoras significativas em VO2pico, frequência cardíaca e pressão arterial pico.

High-intensity interval training in patients with coronary heart disease: Prescription models and perspectives.

Recently, high-intensity interval training (HIIT) has emerged as an alternative and/or complementary exercise modality to continuous aerobic exercise training (CAET) in CHD patients. However, the literature contains descriptions of many HIIT protocols with different stage durations, nature of recovery and intensities. In this review, we discuss the most recent forms of validated HIIT protocols in patients with coronary heart disease (CHD) and how to prescribe and use them during short- and long-term (phase II and III) cardiac rehabilitation programs. We also compare the superior and/or equivalent short- and long-term effects of HIIT versus CAET on aerobic fitness, cardiovascular function, and quality of life; their efficiency, safety, and tolerance; and exercise adherence. Short interval HIIT was found beneficial for CHD patients with lower aerobic fitness and would ideally be used in initiation and improvement stages. Medium and/or long interval HIIT protocols may be beneficial for CHD patients with higher aerobic fitness, and would be ideally used in the improvement and maintenance stages because of their high physiological stimulus. Finally, we propose progressive individualized models of HIIT programs (phase II to III) for patients with CHD and how to ideally use them according to the clinical status of patients and phase of the cardiac rehabilitation program.