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Objective: The study aimed to investigate the effects of the level of contraction during isometric shoulder abduction at different abduction angles on muscle thickness and stiffness of the shoulder girdle in asymptomatic individuals. Design: Measurement properties study. Setting: Biomechanics and motion analysis lab. Participants: Twenty individuals volunteered to participate in this study. Main Outcome Measure: The subjects were tested for morphological and mechanical properties, expressed by thickness and stiffness of the supraspinatus tendon and muscle, and upper trapezius muscle. Moreover, acromiohumeral distance was also evaluated using B-mode ultrasound and shear-wave elastography. Intervention: The thickness and stiffness of the supraspinatus and upper trapezius muscle were assessed at 3 angles of abduction (0°, 60°, and 90°) and 3 levels of contraction (0%, 10%, and 20% of the maximal voluntary isometric contraction) using ultrasonography with shear-wave imaging. Moreover, the acromiohumeral distance was measured to establish the occupation ratio during passive movement. Results: The supraspinatus and upper trapezius muscle thickness and stiffness were significantly greater at 60° shoulder abduction compared with 0°, and 90° compared with 60°, as well as significantly greater at 20% maximal voluntary isometric contraction compared with 0% and 10% maximal voluntary isometric contraction. Thickness and stiffness were significantly greater in the supraspinatus compared with the upper trapezius muscle at all 3 angles of shoulder abduction for all 3 level of contractions. The acromiohumeral distance decreased significantly from 0° to 60° and from 60° to 90°. Conclusion: Morphological and mechanical properties of the supraspinatus and upper trapezius muscles depended on the relative level of muscle contraction and the angle of shoulder abduction. [ABSTRACT FROM AUTHOR]

High-intensity interval training (HIIT) has been suggested as an effective treatment approach of childhood obesity. The objective of the present study was to examine intensity, enjoyment, and perceived exertion of a 4x4-minute play-based HIIT program for children and adolescents with obesity. 83 participants (42.2% girls, 12.3±1.5 years, 57.8% boys, 12.0±1.6 years) completed a 12-week intervention comprising three weekly sessions. After nine sessions (weeks 2, 6, and 11), participants rated perceived exertion (RPE) with a Borg scale and enjoyment of activities using the Physical Activity Enjoyment Scale (PACES). Heart rate (HR) was recorded to assess time spent in high- and moderate-intensity. Participants spent more time in high-intensity during strength-based(P=0.004) and running-based(P=0.007) activities compared to ball games, and more time was spent in moderate-intensity during ball games compared to strength-based(P=0.033) and running-based(P=0.028) activities. Overall, boys spent more time in moderate-intensity than girls(P=0.007). Participants rated RPE lower for ball games than for strength-based(P<0.001) and running-based(P<0.001) activities. Boys rated running-based activities more enjoyable than girls(P=0.021). Exercise intensity and RPE vary by activity in HIIT for children and adolescents with obesity. Ball games led to less high-intensity time and were seen as less exhausting. No differences in RPE or enjoyment were found over time., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Background: Multidisciplinary lifestyle interventions for children with obesity in Denmark often include recommendations regarding physical activity, but no structured exercise program. We hypothesized that adding high-intensity interval training (HIIT) to a multidisciplinary lifestyle intervention would improve BMI z-score (primary outcome), waist circumference, blood pressure, and health-related quality of life (HRQOL)., Methods: This randomized controlled trial included 173 children and adolescents with obesity. Participants were allocated to 12-months lifestyle intervention (N = 83), or 12-month lifestyle intervention accompanied by a 12-week HIIT program (N = 90). HIIT consisted of three weekly sessions and included activities eliciting intensities >85% of maximal heart rate., Results: Attendance rate for the 3-months HIIT intervention was 68.0 ± 23.2%. Dropout was lower in HIIT compared to control at three months (7.8% vs. 20.5%) and 12 months (26.5% vs 48.2%). Changes in BMI z-score did not differ between HIIT and control at 3 months (Mean Difference (MD): 0.01, 95% confidence interval (CI): -0.09; 0.12, P = 0.82) or 12 months (MD: 0.06, CI: -0.07;0.19, P = 0.34). Across randomization, BMI z-score was reduced by 0.11 (CI: 0.17; 0.06, P < 0.01) at 3 months and 0.20 (CI: 0.26;0.14, P < 0.01) at 12 months. At 3 months, HIIT experienced a greater increase in HRQOL of 2.73 (CI: 0.01;5.44, P = 0.05) in PedsQL Child total-score and 3.85 (CI: 0.96; 6.74, P < 0.01) in psychosocial health-score compared to control. At 12 months, PedsQL Child physical-score was reduced by 6.89 (CI: 10.97; 2.83, P < 0.01) in HIIT compared to control. No group differences or changes over time were found for waist circumference or blood pressure., Conclusion: Adding a 12-week HIIT program did not further augment the positive effects of a 12-month lifestyle intervention on BMI z-score. Adding HIIT improved HRQOL after 3 months, but reduced HRQOL at 12 months. Implementation of HIIT in community-based settings was feasible and showed positive effects on adherence to the lifestyle intervention., (© 2024. The Author(s).)