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Objectives: Self-perceptions such as perceived motor competence and psychosocial wellbeing have been identified as important to children's physical activity. The study's purpose was to explore whether perceived motor competence and psychosocial wellbeing were determinants of physical activity, one year after a baseline assessment., Design: Longitudinal study., Methods: A total of 134 children (65.7% boys, 34.3% girls) aged 6-7 years at baseline (2016), and 7-8 years at follow-up (2017) were included in this study. Pearson's correlations assessed associations at baseline and follow-up between moderate- to vigorous-intensity physical activity (MVPA) (accelerometers) and (i) total perceived motor competence and subdomains (the pictorial scale of Perceived Movement Skill Competence) and (ii) psychosocial wellbeing and sub-domains - KidKINDL KINDer Lebensqualitätsfragebogen: Children Quality of Life Questionnaire (KINDL R ). Variables identified as significant in Pearson's correlations were included in mixed model analyses, adjusting for accelerometer wear time, sex and age., Results: Baseline perceived object control skills was associated with MVPA at follow-up (r=0.38, p<0.001), but perceived locomotor skills were not. Self-esteem was the only subdomain of psychosocial wellbeing that demonstrated significant association with MVPA at baseline (r=0.21, p<0.05). Perceived object control (B=1.36, p=0.019, 95% CI [0.23, 2.50]) and self-esteem (B=0.32, p=0.001, 95% CI [0.13, 0.50]) positively predicted MVPA; albeit with small effects., Conclusions: Focusing on improving children's perceived object control and self-reported self-esteem may contribute to children's physical activity participation., (Copyright © 2019. Published by Elsevier Ltd.)

Objectives: To examine the effects of different protocols of high-intensity interval training (HIIT) on VO 2 max improvements in healthy, overweight/obese and athletic adults, based on the classifications of work intervals, session volumes and training periods., Design: Systematic review and meta-analysis., Methods: PubMed, Scopus, Medline, and Web of Science databases were searched up to April 2018. Inclusion criteria were randomised controlled trials; healthy, overweight/obese or athletic adults; examined pre- and post-training VO 2 max/peak; HIIT in comparison to control or moderate intensity continuous training (MICT) groups., Results: Fifty-three studies met the eligibility criteria. Overall, the degree of change in VO 2 max induced by HIIT varied by populations (SMD=0.41-1.81, p<0.05). When compared to control groups, even short-intervals (≤30s), low-volume (≤5min) and short-term HIIT (≤4weeks) elicited clear beneficial effects (SMD=0.79-1.65, p<0.05) on VO 2 max/peak. However, long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4-12weeks) HIIT displayed significantly larger effects on VO 2 max (SMD=0.50-2.48, p<0.05). When compared to MICT, only long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4-12weeks) HIIT showed beneficial effects (SMD=0.65-1.07, p<0.05)., Conclusions: Short-intervals (≤30s), low-volume (≤5min) and short-term (≤4weeks) HIIT represent effective and time-efficient strategies for developing VO 2 max, especially for the general population. To maximize the training effects on VO 2 max, long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4-12weeks) HIIT are recommended., (Copyright © 2019 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)