Association of high amounts of physical activity with mortality risk: a systematic review and meta-analysis.

OBJECTIVES: To systematically review and analyse studies of high amounts of physical activity and mortality risk in the general population. ELIGIBILITY CRITERIA: Inclusion criteria related to follow-up (minimum 2 years), outcome (mortality from all causes, cancer, cardiovascular disease (CVD) or coronary heart disease), exposure (eg, a category of >1000 metabolic equivalent of task (MET) min/week), study design (prospective cohort, nested case control or case-cohort) and reports of cases and person years of exposure categories. INFORMATION SOURCES: Systematic searches were conducted in Embase and Pubmed from database inception to 2 March 2019. RISK OF BIAS: The quality of the studies was assessed with the Newcastle-Ottawa scale. INCLUDED STUDIES: From 31 368 studies identified, 48 were included. Two authors independently extracted outcome estimates and assessed study quality. SYNTHESIS OF RESULTS: We estimated hazard ratios (HRs) using random effect restricted cubic spline dose-response meta-analyses. Compared with the recommended level of physical activity (750 MET min/week), mortality risk was lower at physical activity levels exceeding the recommendations, at least until 5000 MET min/week for all cause mortality (HR=0.86, 95% CI 0.78 to 0.94) and for CVD mortality (HR=0.73, 95% CI 0.56 to 0.95). STRENGTHS AND LIMITATIONS OF EVIDENCE: The strengths of this study include the detailed dose-response analyses, inclusion of 48 studies and examination of sources of heterogeneity. The limitations include the observational nature of the included studies and the inaccurate estimations of amount of physical activity. INTERPRETATION: Compared with the recommended level, mortality risk was lower at physical activity levels well above the recommended target range. Further, there was no threshold beyond which lifespan was compromised. REGISTRATION: PROSPERO CRD42017055727.

Effect of ecological momentary assessment, goal-setting and personalized phone-calls on adherence to interval walking training using the InterWalk application among patients with type 2 diabetes-A pilot randomized controlled trial.

OBJECTIVES: The objective was to investigate the feasibility and usability of electronic momentary assessment, goal-setting and personalized phone-calls on adherence to a 12-week self-conducted interval walking training (IWT) program, delivered by the InterWalk smartphone among patients with type 2 diabetes (T2D). METHODS: In a two-arm pilot randomized controlled trial (Denmark, March 2014 to February 2015), patients with T2D (18-80 years with a Body Mass Index of 18 and 40 kg/m2) were randomly allocated to 12 weeks of IWT with (experimental) or without additional support (control). The primary outcome was the difference between groups in accumulated time of interval walking training across 12 weeks. All patients were encouraged to use the InterWalk application to perform IWT for ≥90 minute/week. Patients in the experimental group made individual goals regarding lifestyle change. Once a week inquiries about exercise adherence was made using an ecological momentary assessment (EMA). In case of consistent self-reported non-adherence, the patients would receive a phone-call inquiring about the reason for non-adherence. The control group did not receive additional support. Information about training adherence was assessed objectively. Usability of the EMA was assessed based on response rates and self-reported satisfaction after 12-weeks. RESULTS: Thirty-seven patients with T2D (66 years, 65% female, hemoglobin 1Ac 50.3 mmol/mol) where included (n = 18 and n = 19 in experimental and control group, respectively). The retention rate was 83%. The experimental group accumulated [95%CI] 345 [-7, 698] minutes of IWT more than the control group. The response rate for the text-messages was 83% (68% for males and 90% for females). Forty-one percent of the experimental and 25% of the control group were very satisfied with their participation. CONCLUSION: The combination inquiry about adherence using EMA, goal-setting with the possibility of follow-up phone calls are considered feasible interventions to attain training adherence when using the InterWalk app during a 12-week period in patients with T2D. Some uncertainty about the effect size of adherence remains. TRIAL REGISTRATION: Clinicaltrials.gov NCT02089477.

Resting Metabolic Rate Does Not Change in Response to Different Types of Training in Subjects with Type 2 Diabetes.

BACKGROUND AND OBJECTIVES: Ambiguous results have been reported regarding the effects of training on resting metabolic rate (RMR), and the importance of training type and intensity is unclear. Moreover, studies in subjects with type 2 diabetes (T2D) are sparse. In this study, we evaluated the effects of interval and continuous training on RMR in subjects with T2D. Furthermore, we explored the determinants for training-induced alterations in RMR. METHODS: Data from two studies, both including T2D subjects, were encompassed in this manuscript. Study 1 was a randomized, crossover study where subjects (n = 14) completed three, 2-week interventions [control, continuous walking training (CWT), interval-walking training (IWT)] separated by washout periods. Training included 10 supervised treadmill sessions, 60 min/session. CWT was performed at moderate walking speed [aiming for 73% of walking peak oxygen uptake (VO2peak)], while IWT was performed as alternating 3-min repetitions at slow (54% VO2peak) and fast (89% VO2peak) walking speed. Study 2 was a single-arm training intervention study where subjects (n = 23) were prescribed 12 weeks of free-living IWT (at least 3 sessions/week, 30 min/session). Before and after interventions, RMR, physical fitness, body composition, and glycemic control parameters were assessed. RESULTS: No overall intervention-induced changes in RMR were seen across the studies, but considerable inter-individual differences in RMR changes were seen in Study 2. At baseline, total body mass (TBM), fat-free mass (FFM), and fat mass were all associated with RMR. Changes in RMR were associated with changes in TBM and fat mass, and subjects who decreased body mass and fat mass also decreased their RMR. No associations were seen between changes in physical fitness, glycemic control, or FFM and changes in RMR. CONCLUSION: Neither short-term continuous or interval-type training, nor longer term interval training affects RMR in subjects with T2D when no overall changes in body composition are seen. If training occurs concomitant with a reduction in fat mass, however, RMR is decreased. CLINICAL TRIALS REGISTRATION WWWCLINICALTRIALSGOV: NCT02320526 and NCT02089477.

Long-term effect of smartphone-delivered Interval Walking Training on physical activity in patients with type 2 diabetes: protocol for a parallel group single-blinded randomised controlled trial.

INTRODUCTION: Physical activity is a cornerstone in type 2 diabetes (T2D) rehabilitation. Effective long-term and low-cost strategies to keep these patients' physically active are needed. However, maintaining physical activity behaviour is difficult once formalised interventions end. Structured exercise training supported by mobile technology and remote feedback is potentially an effective strategy. The objective of the trial is to investigate whether mobile health support using the InterWalk application for smartphones is effective in increasing physical activity levels in persons with T2D over time compared with standard care. We investigate whether Interval Walking Training using the InterWalk application is superior to Danish municipality-based rehabilitation in increasing moderate-and-vigorous physical activity levels in patients with T2D across 52 weeks. Secondary, we hypothesise that a motivational programme added from end of intervention to 52 weeks further increases level of physical activity in everyday life in patients with T2D. METHODS AND ANALYSIS: The trial is a parallel-group, open-labelled, randomised controlled trial with long-term follow-up at 52 week including patients with T2D. The primary outcome is change in moderate-and-vigorous physical activity. The key secondary outcome includes motivation for physical activity behaviour change. Other secondary outcomes are VO2-peak, strength in the lower extremities. Exclusion criterion is medical contraindication to exercise. We include up to 246 patients and randomly allocate them into a control (standard group) or an experimental group (8-12 weeks of IWT supported by the smartphone-based InterWalk application) in a 1:2 fashion. After intervention, the experimental group is randomly allocated into two follow-up conditions with unsupervised IWT with or without motivational support until 52-week follow-up. The intention-to-treat principle is applied. ETHICS AND DISSEMINATION: The local regional Research Ethics Committee in Denmark (H-1-2014-074) and the Danish Data Protection Agency (j.nr. 2014-54-0897) have approved the trial. Positive, negative or inconclusive results will be disseminated in scientific journals and conferences. TRIAL REGISTRATION NUMBER: NCT02341690.

Criterion validity and reliability of a smartphone delivered sub-maximal fitness test for people with type 2 diabetes.

BACKGROUND: Prevention of multi-morbidities following non-communicable diseases requires a systematic registration of adverse modifiable risk factors, including low physical fitness. The aim of the study was to establish criterion validity and reliability of a smartphone app (InterWalk) delivered fitness test in patients with type 2 diabetes. METHODS: Patients with type 2 diabetes (N = 27, mean (SD) age 64.2 (5.9) years, BMI 30.0 (5.1) kg/m2, (30 % male)) completed a 7-min progressive walking protocol twice (with and without encouragement). VO2 during the test was assessed using indirect calorimetry and the acceleration (vector magnitude) from the smartphone was obtained. The vector magnitude was used to predict VO2peak along with the co-variates weight, height and sex. The validity of the algorithm was tested when the smartphone was placed in the right pocket of the pants or jacket. The algorithm was validated using leave-one-out cross validation. Test-retest reliability was tested in a subset of participants (N = 10). RESULTS: The overall VO2peak prediction of the algorithm (R2) was 0.60 and 0.45 when the smartphone was placed in the pockets of the pants and jacket, respectively (p < 0.001). The mean bias (limits of agreement) in the cross validation was-0.4 (38) % (pants) and-0.1 (46) % (jacket). When the smartphone was placed in the jacket a significant intensity dependent bias (r = 0.5, p = 0.02) was observed. The test-retest intraclass correlations were 0.85 and 0.86 (p < 0.001), for the pants and jacket, respectively. No effects of encouragement were observed on test performance. CONCLUSION: In conclusion, the InterWalk Fitness Test is accurate and reliable for persons with type 2 diabetes when the smartphone is placed in the side pocket of the pants for. The test could give a fair estimate of the CRF in absence of a progressive maximal test during standardized conditions with the appropriate equipment. TRIAL REGISTRATION: www.clinicaltrials.org (NCT02089477), first registered (prospectively) on March 14th 2014.