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Purpose: High-intensity interval training (HIIT) may lead to superior cardiometabolic improvements when compared with moderate-intensity continuous training (MICT). However, adherence to HIIT requires examination. The purpose of this pilot study was to examine moderate-to-vigorous physical activity (MVPA) adherence 24 wk after a brief counseling intervention combined with either HIIT or MICT., Methods: Individuals at high risk of type 2 diabetes (T2D) were randomized to HIIT (n = 15) or MICT (n = 17) and completed 10 exercise sessions accompanied by a brief 10-min counseling intervention over a 2-wk period. Objectively measured purposeful MVPA (accelerometry) and cardiorespiratory fitness (V˙O2peak) were assessed at baseline and 24 wk postintervention. Self-regulatory efficacy and task self-efficacy were examined at baseline, postintervention, and 24 wk postintervention. Using an intention-to-treat analysis, change scores were calculated for HIIT and MICT and compared between groups., Results: Individuals assigned to HIIT increased their MVPA by 53 min (Cohen's d = 1.52) at 24 wk compared with 19 min in MICT. Both HIIT and MICT increased relative V˙O2peak by 2 and 1 mL·kg·min, respectively. Participants in both groups increased in their self-regulatory and task self-efficacy postintervention, but both groups demonstrated similar decline at 24 wk., Conclusion: This pilot intervention was successful in increasing, and maintaining, free-living MVPA over a 24-wk period in individuals at high risk of T2D. Speculation that HIIT is inappropriate or unattainable for overweight individuals at high risk of T2D may be unfounded.

High-intensity interval training (HIIT) elicits health benefits but it is unclear how HIIT impacts sedentary behaviour. In this preliminary study, we compared the effects of supervised HIIT or moderate-intensity continuous training (MICT) on sedentary time in overweight/obese adults. In both groups, percentage of time spent in sedentary activities was significantly reduced during the supervised exercise intervention (time main effect, P = 0.03), suggesting that both HIIT and MICT replaced time spent previously being sedentary.

Background: Childhood overweight and obesity is a major public health concern. Community-based interventions have the potential to reach caregivers and children. However, the overall health impact of these programs is rarely comprehensively assessed. This study evaluated a physical activity and healthy eating family program (Healthy Together; HT) using the RE-AIM framework., Methods: Ten sites implemented the 5-week program. Thirty-nine staff members and 277 program participants (126 caregivers [M age  = 35.6] and 151 children [M age  = 13]) participated in the evaluation. Each RE-AIM dimension was assessed independently using a mixed-methods approach. Sources of data included archival records, interviews and surveys. Effectiveness outcome variables were assessed at pre- and post-intervention and 6-month follow-up., Results: Reach: HT participants were almost entirely recruited from existing programs within sites. Effectiveness: Caregivers' nutrition related efficacy beliefs increased following HT (ps < .03). Participation in HT was not associated with significant changes in physical activity or nutrition behaviour or perceived social support (ps > .05). Knowledge surrounding healthy diets and physical activity increased in children and caregivers (ps < .05). Adoption: Thirty-five percent of sites approached to implement HT expressed interest. The 10 sites selected recruited existing staff members to implement HT., Implementation: Program objectives were met 72.8% of the time and 71 adaptations were made. HT was finance- and time-dependent. Maintenance: Two sites fully implemented HT in the follow-up year and 5 sites incorporated aspects of HT into other programs., Conclusions: Working alongside organizations that develop community programs to conduct comprehensive, arms-length evaluations can systematically highlight areas of success and challenges. Overall HT represents a feasible community-based intervention; however further support is required in order to ensure the program is effective at positively targeting the desired outcomes. As a result of this evaluation, modifications are currently being implemented to HT.

Exercise can have anti-inflammatory effects in obesity, but the optimal type and intensity of exercise are not clear. This study compared short-term high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) in terms of improvement in cardiorespiratory fitness, markers of inflammation, and glucose control in previously inactive adults at elevated risk of developing type 2 diabetes. Thirty-nine inactive, overweight/obese adults (32 women) were randomly assigned to 10 sessions over 2 wk of progressive HIIT (n = 20, four to ten 1-min sessions at ∼90% peak heart rate, 1-min rest periods) or MICT (n = 19, 20-50 min at ∼65% peak heart rate). Before and 3 days after training, participants performed a peak O2 uptake test, and fasting blood samples were obtained. Both HIIT (1.8 ± 0.4 vs. 1.9 ± 0.4 l/min, pre vs. post) and MICT (1.8 ± 0.5 vs. 1.9 ± 0.5 l/min, pre vs. post) improved peak O2 uptake (P < 0.001) and lowered plasma fructosamine (P < 0.05). Toll-like receptor (TLR) 4 (TLR4) expression was reduced on lymphocytes and monocytes after both HIIT and MICT (P < 0.05) and on neutrophils after MICT (P < 0.01). TLR2 on lymphocytes was reduced after HIIT and MICT (P < 0.05). Plasma inflammatory cytokines were unchanged after training in both groups, but MICT led to a reduction in fasting plasma glucose (P < 0.05, 5.9 ± 1.0 vs. 5.6 ± 1.0 mmol/l, pre vs. post). Ten days of either HIIT or MICT can improve cardiorespiratory fitness and glucose control and lead to reductions in TLR2 and TLR4 expression. MICT, which involved a longer duration of exercise, may be superior for reducing fasting glucose., (Copyright © 2015 the American Physiological Society.)

Aims: High-intensity interval training (HIIT) leads to improvements in various markers of cardiometabolic health but adherence to HIIT following a supervised laboratory intervention has yet to be tested. We compared self-report and objective measures of physical activity after one month of independent exercise in individuals with prediabetes who were randomized to HIIT (n = 15) or traditional moderate-intensity continuous training (MICT, n = 17)., Method: After completing 10 sessions of supervised training participants were asked to perform HIIT or MICT three times per week for four weeks., Results: Individuals in HIIT (89 ± 11%) adhered to their prescribed protocol to a greater extent than individuals in MICT (71 ± 31%) as determined by training logs completed over one-month follow-up (P = 0.05, Cohen's d = 0.75). Minutes spent in vigorous physical activity per week measured by accelerometer were higher in HIIT (24 ± 18) as compared to MICT (11 ± 10) at one-month follow-up (P = 0.049, Cohen's d = 0.92). Cardiorespiratory fitness and systolic blood pressure assessed at one-month follow-up were equally improved (P's < 0.05)., Conclusions: This study provides preliminary evidence that individuals with prediabetes can adhere to HIIT over the short-term and do so at a level that is greater than MICT.

Affect experienced during an exercise session is purported to predict future exercise behaviour. Compared to continuous moderate-intensity exercise (CMI), the affective response to continuous vigorous-intensity exercise (CVI) has consistently been shown to be more aversive. The affective response, and overall tolerability to high-intensity interval training (HIT), is less studied. To date, there has yet to be a comparison between HIT, CVI, and CMI. The purpose of this study was to compare the tolerability and affective responses during HIT to CVI and CMI. This study utilized a repeated measures, randomized, counter-balanced design. Forty-four participants visited the laboratory on four occasions. Baseline fitness testing was conducted to establish peak power output in Watts (W peak). Three subsequent visits involved a single bout of a) HIT, corresponding to 1-minute at ∼ 100% W peak and 1-minute at ∼ 20% W peak for 20 minutes, b) CMI, corresponding to ∼ 40% W peak for 40 minutes, and c) CVI, corresponding to ∼ 80% W peak for 20 minutes. The order of the sessions was randomized. Affective responses were measured before, during and after each session. Task self-efficacy, intentions, enjoyment and preference were measured after sessions. Participants reported greater enjoyment of HIT as compared to CMI and CVI, with over 50% of participants reporting a preference to engage in HIT as opposed to either CMI or CVI. HIT was considered more pleasurable than CVI after exercise, but less pleasurable than CMI at these times. Despite this participants reported being just as confident to engage in HIT as they were CMI, but less confident to engage in CVI. This study highlights the utility of HIT in inactive individuals, and suggests that it may be a viable alternative to traditionally prescribed continuous modalities of exercise for promoting self-efficacy and enjoyment of exercise.