Shuttle Time for Seniors: The Impact of 8-Week Structured Badminton Training on Markers of Healthy Aging and Evaluation of Lived Experiences-A Quasi-Experimental Study.

BACKGROUND/OBJECTIVES: Engagement in sport offers the potential for improved physical and psychological well-being and has been shown to be beneficial for promoting healthy aging. Opportunities for older adults to (re)engage with sport are limited by a paucity of age-appropriate introductory sports intervention programs. As such, the study evaluated the efficacy of a newly designed 8-week badminton training program (Shuttle Time for Seniors) on markers of healthy aging and the lived experiences of participation. METHODS: Forty-three older adults assigned to a control (N = 20) or intervention group (N = 23) completed pre-post assessment of physical and cognitive function, self-efficacy for exercise, and well-being. Focus groups were conducted for program evaluation and to understand barriers and enablers to sustained participation. RESULTS: Those in the intervention group increased upper body strength, aerobic fitness, coincidence anticipation time, and self-efficacy for exercise. Objectively improved physical and cognitive functions were corroborated by perceived benefits indicated in thematic analysis. Shuttle Time for Seniors was perceived as appropriate for the population, where the age-appropriate opportunity to participate with likeminded people of similar ability was a primary motivator to engagement. Despite willingness to continue playing, lack of badminton infrastructure was a primary barrier to continued engagement. CONCLUSION: Shuttle Time for Seniors offered an important opportunity for older adults to (re)engage with badminton, where the physical and psychosocial benefits of group-based badminton improved facets important to healthy aging. Significance/Implications: Age-appropriate introductory intervention programs provide opportunity for older adults to (re)engage with sport. However, important barriers to long-term engagement need to be addressed from a whole systems perspective.

Effect of high-fat diet on isometric, concentric and eccentric contractile performance of skeletal muscle isolated from female CD-1 mice.

Despite evidence inferring muscle and contractile mode-specific effects of high-fat diet (HFD), no study has yet considered the impact of HFD directly on eccentric muscle function. The present work uniquely examined the effect of 20-week HFD on the isometric, concentric and eccentric muscle function of isolated mouse soleus (SOL) and extensor digitorum longus (EDL) muscles. CD-1 female mice were randomly split into a control (n = 16) or HFD (n = 17) group and for 20 weeks consumed standard lab chow or HFD. Following this period, SOL and EDL muscles were isolated and assessments of maximal isometric force and concentric work loop (WL) power were performed. Each muscle was then subjected to either multiple concentric or eccentric WL activations. Post-fatigue recovery, as an indicator of incurred damage, was measured via assessment of concentric WL power. In the EDL, absolute concentric power and concentric power normalised to muscle mass were reduced in the HFD group (P < 0.038). HFD resulted in faster concentric fatigue and reduced eccentric activity-induced muscle damage (P < 0.05). For the SOL, maximal isometric force was increased, and maximal eccentric power normalised to muscle mass and concentric fatigue were reduced in the HFD group (P < 0.05). HFD effects on eccentric muscle function are muscle-specific and have little relationship with changes in isometric or concentric function. HFD has the potential to negatively affect the intrinsic concentric and eccentric power-producing capacity of skeletal muscle, but a lack of a within-muscle uniform response indicates disparate mechanisms of action which require further investigation.

Child Soccer Players' Perceptions of Strength and Conditioning Training: A Multimethod Approach Using Write, Draw, Show and Tell.

PURPOSE: The use of strength and conditioning training in childhood is a hot topic surrounded by myths and misconceptions. Despite scientific evidence supporting the safety and benefits of this training for children, the lack of representation of their voices poses a challenge in designing training programs that meet their specific needs and requirements. METHODS: Children's views, experiences, and perceptions of strength and conditioning training were explored by Write, Draw, Show and Tell techniques. Sixteen grassroots soccer players aged 11-12 years took part in one of 3 focus groups exploring the topic. Data were analyzed following an inductive approach enabling themes to be explored and later deductive analyses using the Youth Physical Activity Promotion model to create pen profile diagrams. RESULTS: Strength and conditioning were frequently associated with muscle growth, coordination, endurance, and rest. Enabling factors included autonomy, resilience, physical development, and training opportunities. Reinforcing factors included social support, social interference, coaches' communication, role models, and the ways of implementation. CONCLUSIONS: Participants favor integrating strength and conditioning into their soccer training rather than conducting it as a separate session, which is reflected in their enjoyment. Nonetheless, children remain apprehensive about the potential effects of this type of training on their growth.

High-fat diet effects on contractile performance of isolated mouse soleus and extensor digitorum longus when supplemented with high dose vitamin D.

Evidence suggests vitamin D3 (VD) supplementation can reduce accumulation of adipose tissue and inflammation and promote myogenesis in obese individuals, and thus could mitigate obesity-induced reductions in skeletal muscle (SkM) contractility. However, this is yet to be directly investigated. This study, using the work-loop technique, examined effects of VD (cholecalciferol) supplementation on isolated SkM contractility. Female mice (n = 37) consumed standard low-fat diet (SLD) or high-fat diet (HFD), with or without VD (20,000 IU/kg-1 ) for 12 weeks. Soleus and EDL (n = 8-10 per muscle per group) were isolated and absolute and normalized (to muscle size and body mass) isometric force and power output (PO) were measured, and fatigue resistance determined. Absolute and normalized isometric force and PO of soleus were unaffected by diet (P > 0.087). However, PO normalized to body mass was reduced in HFD groups (P < 0.001). Isometric force of extensor digitorum longus (EDL) was unaffected by diet (P > 0.588). HFD reduced EDL isometric stress (P = 0.048) and absolute and normalized PO (P < 0.031), but there was no effect of VD (P > 0.493). Cumulative work during fatiguing contractions was lower in HFD groups (P < 0.043), but rate of fatigue was unaffected (P > 0.060). This study uniquely demonstrated that high-dose VD had limited effects on SkM contractility and did not offset demonstrated adverse effects of HFD. However, small and moderate effect sizes suggest improvement in EDL muscle performance and animal morphology in HFD VD groups. Given effect sizes observed, coupled with proposed inverted U-shaped dose-effect curve, future investigations are needed to determine dose/duration specific responses to VD, which may culminate in improved function of HFD SkM.

Playing it safe: The relationship between parent attitudes to risk and injury, and children's adventurous play and physical activity.

BACKGROUND: Children naturally seek risk in play and adventurous play outdoors confers many benefits, including the potential to increase moderate-to-vigorous physical activity (MVPA). This study aimed to investigate the relationship between parent attitudes to risk and injury, and their elementary school-aged child's daily adventurous play and MVPA. METHODS: A panel sample of 645 Australian parents/guardians completed an online survey consisting of several validated measures of risk and injury attitudes, and physical activity and play behaviour. Data were analysed via descriptive statistics, univariate and multivariable regressions using Stata 17. A series of exploratory univariate logistic regressions were conducted, followed by a series of multivariable logistic regressions fitted to test the association between parent risk and injury attitudes and (i) children's MVPA, (ii) active play and (iii) adventurous play, while adjusting for socio-demographic factors. RESULTS: Most adult participants (81%) were female. The mean age of the child participants (53% male) was 8.6 years (SD = 2.4). On average, parents were positive about children's engagement with risk, however, 78% of parents had low tolerance of risk when presented with specific play scenarios, and attitudes towards injuries varied, with mothers more concerned than fathers. After adjusting for confounders, children with parents who were tolerant of risk in play were more likely to meet the MVPA guideline of ≥60 min daily (OR 2.86, CI: 1.41, 5.82, p < 0.004) and spend more time playing adventurously (OR 3.03, CI: 1.82, 5.06, p < 0.001). Positive associations for MVPA and adventurous play were observed across all models examining parent attitudes to risk and injury. Younger children engaged in more play and physical activity, however, more positive parent attitudes appeared to moderate the age-related influences. CONCLUSIONS: We found a divergence between the outcomes parents desire for their children through engagement with risk and the play activities they are comfortable with in practice. Parent attitudes to risk and injury are potentially modifiable factors that may increase children's affordances for adventurous play and physical activity. Interventions that provide parents with practical approaches to address injury concerns and support children's risk-taking in play outdoors are recommended.

Agreement between Force Platform and Smartphone Application-Derived Measures of Vertical Jump Height in Youth Grassroots Soccer Players.

Given the importance of vertical jump assessments as a performance benchmarking tool, the assessment of neuromuscular function and indicator of health status, accurate assessment is essential. This study compared countermovement jump (CMJ) height assessed using MyJump2 (JHMJ) to force-platform-derived jump height calculated from time in the air (JHTIA) and take-off velocity (JHTOV) in youth grassroots soccer players. Thirty participants (Age: 8.7 ± 0.42 yrs; 9 females) completed bilateral CMJs on force platforms whilst jump height was simultaneously evaluated using MyJump2. Intraclass correlation coefficients (ICC), Standard error of measurement (SEM), coefficient of variance (CV) and Bland-Altman analysis were used to compare performance of MyJump2 to force-platform-derived measures of CMJ height. The median jump height was 15.5 cm. Despite a high level of agreement between JHTIA and JHTOV (ICC = 0.955), CV (6.6%), mean bias (1.33 ± 1.62 cm) and 95% limits of agreement (LoA -1.85-4.51 cm) were greater than in other comparisons. JHMJ performed marginally better than JHTIA when compared to JHTOV (ICC = 0.971; 95% CI's = 0.956-0.981; SEM = 0.3 cm; CV = 5.7%; mean bias = 0.36 ± 1.61 cm; LoA = -3.52-2.80 cm). Irrespective of method, jump height did not differ between males and females (p > 0.381; r < 0.093), and the comparison between assessment tools was not affected by sex. Given low jump heights achieved in youth, JHTIA and JHMJ should be used with caution. JHTOV should be used to guarantee accuracy in the calculation of jump height.

The Acute Effects of Cognitively Demanding Physical Activity on Inhibitory and Affective Responses in Children: An Online-Based Mixed Methods Approach.

This online study investigated the acute effects of a cognitively demanding physical activity (CDPA) vs a simple physical activity (SPA) bout on children's inhibitory and affective responses. Using a counterbalanced within-subjects' crossover design, thirty-nine participants aged 9−12 years old (29 boys; Mage = 11 ± 1 years) performed a CDPA and a SPA bout online (via ZOOM) for 15 min. Inhibition (Stroop test) was measured at the baseline, 1 and 30 min following the physical activity (PA) bouts, and self-report measures of affect, mental and physical exertion were taken prior, during and post-PA. Additionally, 31 children took part in semi-structured focus groups to explore the factors affecting their enjoyment. The quantitative results suggest no significant differences on inhibitory responses, affect and physical exertion (all p > 0.05). However, the CDPA induced more mental exertion than the SPA did (p < 0.05). In the focus groups, four themes were identified: physical exertion (e.g., tiredness), social (e.g., teams/groups), environment (e.g., outdoors and competition) and emotional (e.g., fun/enjoyment). Some children (n = 18) reported that the CDPA condition confused them, and to make these activities more interesting and enjoyable, they suggested performing the activities outdoors (n = 15) and including other children as part of a group/team (n = 19). The findings suggest no additional benefit of a cognitively enriched physical activity compared to an SPA bout on the inhibitory responses, affect and enjoyment. Using the instructions provided and given the low cost, the easy administration and the minimal amount of equipment and time involved, either of the approaches may be used in a diversity of contexts (i.e., online, schools or outdoors), and it is worth exploring the effects of these conditions on other aspects of executive function.

"Football- It's in Your Blood"-Lived Experiences of Undertaking Recreational Football for Health in Older Adults.

Physical inactivity is prevalent in older adults and contributes to age-related decline in function, health, well-being, and quality of life. Recreational football for older adults has shown promise for promoting health benefits. This study explores the lived experiences of older adults engaging in a walking and recreational football intervention and identifies factors that affect behaviours and can encourage change in this population. A purposive sample (n = 14; aged 67 ± 5 years) of the lived experiences of those participating in a recreational football intervention took part in two focus groups. The participants' responses were grouped into three-time reflecting specific points in their lives: what stopped them from playing football, what got them playing, and what is needed for them to continue playing in the future. Within each of these time points in their lives, themes were identified. The key findings and practical recommendations were that football needs to be adapted and local, that the priority to play football changes over time, and that football itself is a fundamentally intrinsic motivator; 'it's in your blood'. The findings can be used to inform future interventions, encourage participation, and advise on the best practices for key stakeholders in the physical activity domain.

The Influence of Easing COVID-19 Restrictions on the Physical Activity Intentions and Perceived Barriers to Physical Activity in UK Older Adults.

COVID-19 has had profound effects on physical activity behaviours of older adults, and understanding this impact is essential to driving public health policies to promote healthy ageing. The present study aimed to determine; (1) intended physical activity behaviours of older adults following the easing of UK COVID-19 restrictions; (2) the relationship between self-reported physical activity and intended physical activity behaviour; (3) perceived barriers to achieving the intended physical activity goal. Ninety-six participants (74.8 ± 4.4 years; 52 female) from a longitudinal study examining the impact of COVID-19 on physical activity were recruited. Participants outlined their future physical activity intentions and completed the COM-B Self Evaluation Questionnaire. Participants were split into groups based on their intention to 'Maintain' (n = 29), 'Increase' (n = 38) or 'Return' (n = 29) to pre-COVID-19 physical activity. Self-reported physical activity undulated over the pandemic but was mostly equivalent between groups. Intended physical activity behaviour was independent of self-report physical activity. Capability and motivation factors were the most frequently cited barriers to the intended physical activity behaviour, with a greater number of capability barriers in the 'Return' group. Such barriers should be considered in the COVID-19 recovery public health physical activity strategy for promoting healthy ageing.

The Effect of 12-Weeks Recreational Football (Soccer) for Health Intervention on Functional Movement in Older Adults.

There is growing evidence that recreational football offers health benefits for older adults and an important pathway for physical activity for older adult groups. Despite anecdotal evidence that recreational football is beneficial for older adults, no empirical data are available to support this assertion. This study addressed this issue and examined the effects of a 12-week recreational football intervention on the functional fitness of older adults. Using a pre-post case-control design, thirteen males, aged 61-73 years (mean age ± SD = 66 ± 4 years) undertook a twice-weekly, 12-week recreational football for health intervention, and were matched with a control group, comprising thirteen males, aged 62-78 years (mean age ± SD = 66 ± 4 years) who maintained their typical exercise habits during the intervention period. Pre- and postintervention, participants underwent assessment of functional fitness, using the Rikli and Jones functional fitness battery as well as an assessment of body fatness, via bioelectrical impedance analysis and dominant handgrip strength using handgrip dynamometry. Results from a series of 2 (pre-post) X 2 (intervention vs. control) repeated-measures ANOVAs indicate significant pre-post X group interactions for the 30-second chair stand (p = 0.038, Pƞ2 = 0.168), 8-foot timed up and go (p = 0.001, Pƞ2 = 0.577) and 6 min walk test (p = 0.036, Pƞ2 = 0.171). In all cases, performance improved significantly after the intervention for the football intervention group but not the control group. There were no significant differences in the 30 s arm curl test or dominant handgrip strength (p > 0.05). There was a non-significant trend (p = 0.07, Pƞ2 = 0.127) towards a pre-post X group interaction for body fatness, showing a decreased percent body fat for the intervention group over the control group. The results of the present study demonstrate the utility of recreational football as a physical activity intervention in older adults to improve functional movement.

"Sharpening Your Mind, Strengthening Your Body" Parental Perceptions on the Use of Strength and Conditioning in Children and Youth.

Although strength and conditioning is beneficial and safe for children to engage in there remain myths and misconceptions form parents regarding its use which prevent its widespread take up. This study explored parents' attitudes and beliefs about strength and conditioning in their children. Thirty-one parents (21 dads, 10 mums) took part in one of four focus groups exploring the topic. Thematic analysis was used resulting in themes and sub themes centred on: Beliefs; Determinants; Coach Education; Coach Communication; and Relationship to the Game. There were also smaller aspects of the focus groups which touched upon autonomy as a concept related to implementation of strength and conditioning specifically. Overall, parents of children who play grassroots sport hold generally positive perceptions on use of strength and conditioning with their children, considering it beneficial for both physical and mental development. Key factors relating to successful implementation of strength and conditioning for children focus on having a qualified coach in that particular area (rather than a generic sports coach), effective communication between coach and parents, and coach and children in terms of the benefits of engaging with strength and conditioning.

Exploring the Acute Effects of the Daily Mile™ vs. Shuttle Runs on Children's Cognitive and Affective Responses.

BACKGROUND: This study investigated the acute effects of two physical activity (PA) bouts on children's cognitive and affective responses. METHODS: Twenty-nine participants (16 boys and 13 girls; Mage = 9.34 years, SD = 0.48), using a within-subjects crossover design, performed three 15-min conditions: (a) TDM-The Daily Mile™; (b) 12 repeated 30-45-s shuttle runs at ≥ 85% HRMAX; and (c) a sedentary control condition. Cognitive performance (i.e., Stroop, Digit Span, and Corsi blocks) was measured before PA and 1 and 30 min post-PA. Felt Arousal and Feeling Scale self-report scales were administered before, during, and after PA. RESULTS: The results show no changes following the TDM condition relative to the sedentary control condition in cognitive responses. However, when comparing the shuttle runs condition to the sedentary control condition, participants showed higher arousal, an improved reaction time, and lower self-reported pleasure at 1 min post-PA. Nevertheless, at 30 min post-PA, participants' pleasure values were higher in the shuttle runs condition than they were before PA. CONCLUSIONS: When comparing PA conditions, shuttle runs enhanced reaction time and might thus be seen as an option to implement or modify PA opportunities in school settings.

"Children are precious cargo; we don't let them take any risks!": Hearing from adults on safety and risk in children's active play in schools: a systematic review.

BACKGROUND: Understanding determinants of children's outdoor play is important for improving low physical activity levels, and schools are a key setting for both. Safety concerns shape children's opportunity to play actively outdoors, therefore, this qualitative evidence synthesis aimed to i) examine adult (e.g., parent, teacher, yard supervisor, principal) perspectives on safety and risk in children's active play during recess in elementary and/or middle schools, and ii) identify how safety and risk influence playground supervision and decision making in this setting. METHODS: Six electronic databases were systematically searched in March 2021, with an updated search in June 2022. Records were screened against eligibility criteria using Covidence software, and data extraction and synthesis were performed using predesigned coding forms in Microsoft Excel and NVivo. Framework synthesis methodology was employed, guided by a conceptual framework structured on the socio-ecological model (SEM) and affordance theory. RESULTS: From 10,370 records, 25 studies were included that represented 608 adults across 89 schools from nine countries. The synthesis identified 10 constraining and four affording factors that influenced whether school staff were risk-averse or risk tolerant during recess, and, in turn, the degree to which children's play was managed. Constraining factors stemmed from fears for children's physical safety, and fear of blame and liability in the event of playground injury, which shaped parent, school staff and institutional responses to risk. Interrelated factors across SEM levels combined to drive risk-averse decision making and constraining supervision. Emerging evidence suggests children's active play in schools can be promoted by fostering a risk tolerant and play friendly culture in schools through play facilitation training (e.g., risk-reframing, conflict resolution) and engaging stakeholders in the development of school policies and rules that balance benefits of play against potential risks. CONCLUSIONS: Findings show several socio-cultural factors limited the ability of school staff to genuinely promote active play. Future work should seek to foster risk tolerance in schools, challenge the cultural norms that shape parent attitudes and institutional responses to risk in children's play, and explore novel methods for overcoming policy barriers and fear of liability in schools. TRIAL REGISTRATION: PROSPERO registration: CRD42021238719.

Perception of Affordances for Dribbling in Soccer: Exploring Children as Architects of Skill Development Opportunity.

This study examined affordance perception for soccer dribbling using a mixed-methods approach in male grassroots soccer players. We examined how children construct and perceive skills practices for dribbling in soccer. Fourteen boys aged 10-11 years (Mean ± SD = 10.8 ± 0.4 years) who were regularly engaged in grassroots soccer participated in the present study. Children were provided with ten soccer cones and asked to create their own soccer dribbling pattern that would enable them to maximise the number of touches with a football and then dribble the ball in the pattern they had created for a 1 min period. Children were interviewed to explore their perception of affordances for soccer dribbling. The test of gross motor development-3 was used to assess fundamental movement skills (FMS), and the UGent soccer dribbling test was used to assess soccer dribbling skills. Children self-rated their own ability for soccer dribbling, as did their coaches. Pearson's correlations were employed to examine the associations between quantitative variables, and thematic analysis was used to explore qualitative data. Results of the present study suggest that those children who created patterns with less space between cones accrued more touches of the football in their dribbling task (r = -0.671, p = 0.03). Children with a higher perception of their own dribbling ability had higher scores for FMS (r = 0.604, p = 0.049). Those children who scored better in actual soccer dribbling had higher scores for FMS (r = -0.746, p = 0.012) and were rated as better dribblers by their coaches (r = -0.67, p = 0.03). Interview data suggest a feedback loop between perception of ability and actual ability, which influenced the dribbling patterns that were created. This suggests that dribbling performance is scaled to the (perceived) action capabilities of the children, and children can act as architects in their own skill development.

"All the fun stuff, the teachers say, 'that's dangerous!'" Hearing from children on safety and risk in active play in schools: a systematic review.

BACKGROUND: Active play is vital for healthy child development, and schools are a valuable setting to promote this behaviour. Understanding the determinants of children's physical activity behaviour during recess, particularly the role of risk-taking and the influence safety concerns have on active play, is required. This systematic review aimed to 1) synthesise qualitative research with children that explored their perceptions of safety and risk in active play during recess in elementary and/or middle school, and 2) develop a model from the findings to guide efforts in schools to optimise children's active play opportunities during recess. METHODS: Six online databases were systematically searched for articles published between January 2000 and March 2021. Following PRISMA guidelines, records were screened against eligibility criteria using Covidence software, and data extraction and synthesis was conducted using customised forms in Excel and NVivo software. Framework synthesis methodology was employed, conceptually guided by Bronfenbrenner's socio-ecological model and Gibson's affordance theory. RESULTS: Of 9664 records, 31 studies met inclusion criteria, representing 1408 children across 140 schools from 11 countries. An emergent conceptual framework was developed encompassing 23 risk and safety themes and 10 risky play types that children desired in schools. Individual characteristics (age, gender, physical literacy) influenced children's engagement with risk and how they kept themselves safe. Across outer SEM levels, factors interacted to constrain or afford children's active play. Socio-cultural factors (supervision practices, rules, equipment restrictions) constrained active play, which children perceived were driven by adults' concern with physical safety. These factors contributed to a cycle of risk-averse decision making and diminished play affordances, which could inadvertently exacerbate safety issues. A model for risk tolerance in children's active play has been proposed. CONCLUSIONS: The findings show a disparity between the active play children want in schools and what they are able to do. Future work should balance the concerns of adults against the active play children want, involve children in decisions about playground policy, and foster a risk-tolerant culture in schools.

Fundamental movement skills and perceived competence, but not fitness, are the key factors associated with technical skill performance in boys who play grassroots soccer.

OBJECTIVE: This study examined the association between fitness, fundamental movement skills (FMS) and perceived competence on technical skills in boys engaged in grassroots soccer. Methods: Sixty boys (8-12 years of age, Mean ± SD = 10 ± 1 years) undertook assessment of FMS, perceived competence, physical fitness (15m sprint speed, standing long jump distance and seated 1kg medicine ball throw as a composite z-score) and technical skills (dribbling, passing and shooting as a composite z-score). RESULTS: Multiple backwards linear regression was used to determine to amount of variance in technical skill explained by FMS, perceived competence and fitness. Results indicated a significant model (F 3,58= 42.04, P = .0001, Adj R2 = .680) which explained 68% of the variance in technical skills. Perceived competence (ß=.316, P =.001), Total FMS (ß=.140, P =.002), and chronological age (ß=.863), P =.001) significantly contributed to the model. CONCLUSION: This study demonstrates that better technical skills (passing, dribbling, shooting) in youth soccer are explained, alongside age, by being competent in FMS and having a more positive perception of competence. Coaches should therefore seek to encourage development of these factors during childhood for the benefit of technical skill performance.

High-fat diet affects measures of skeletal muscle contractile performance in a temperature-specific manner but does not influence regional thermal sensitivity.

The present study examined whether high-fat diet (HFD) consumption for 20 weeks had a temperature-specific effect on the contractile performance and regional thermal sensitivity of isolated mouse soleus and diaphragm muscle. Four-week-old female CD-1 mice were randomly selected to consume either a standard laboratory diet or a standard laboratory diet in conjunction with a HFD for 20 weeks. Peripheral soleus and core diaphragm were isolated from each animal and maximal isometric force and work loop power were assessed at 20, 28, 35 and 40°C. Increasing temperature to 35°C resulted in greater isometric stress, lower activation and relaxation time, and higher work loop power in both muscles. A further increase in temperature to 40°C did not affect isometric force but increased work loop power output of the soleus. Conversely, isometric force of the diaphragm was reduced and work loop power maintained when temperature was increased to 40°C. HFD consumption resulted in greater isometric force and absolute work loop power of the soleus and reduced isometric stress of the diaphragm, effects that were less apparent at lower temperatures. When the relationship between temperature and each measure of contractile function was examined by linear regression, there was no difference in slope between the control or HFD groups for either the soleus or diaphragm. These results indicate that whilst contractile function initially increases with temperature, the temperature to elicit maximal performance is muscle and contractile mode specific. Furthermore, HFD effects on contractile function are temperature specific, but HFD does not influence the relationship between temperature and performance.

Effect of stimulation frequency on force, power and fatigue of isolated mouse extensor digitorum longus muscle.

This study examined the effect of stimulation frequency (140, 200, 230 and 260 Hz) on isometric force, work loop (WL) power and the fatigue resistance of extensor digitorum longus (EDL) muscle (n=32), isolated from 8- to 10-week-old CD-1 female mice. Stimulation frequency had significant effects on isometric properties of isolated mouse EDL, whereby increasing stimulation frequency evoked increased isometric force, quicker activation and prolonged relaxation (P<0.047) up to 230 Hz and above; thereafter, force and activation did not differ (P>0.137). Increasing stimulation frequency increased maximal WL power output (P<0.001; 140 Hz, 71.3±3.5; 200 Hz, 105.4±4.1; 230 Hz, 115.5±4.1; 260 Hz, 121.1±4.1 W kg-1), but resulted in significantly quicker rates of fatigue during consecutive WLs (P<0.004). WL shapes indicate impaired muscle relaxation at the end of shortening and subsequent increased negative work appeared to contribute to fatigue at 230 and 260 Hz, but not at lower stimulation frequencies. Cumulative work was unaffected by stimulation frequency, except at the start of the fatigue protocol, where 230 and 260 Hz produced more work than 140 Hz (P<0.039). We demonstrate that stimulation frequency affects force, power and fatigue, but these effects are not uniform between different assessments of contractile performance. Therefore, future work examining the contractile properties of isolated skeletal muscle should consider increasing the stimulation frequency beyond that needed for maximal force when examining maximal power but should utilise a sub-maximal stimulation frequency for fatigue assessments to avoid a high degree of negative work atypical of in vivo function.

Barriers and Facilitators to Physical Activity and FMS in Children Living in Deprived Areas in the UK: Qualitative Study.

Using the socio-ecological model, this qualitative study aimed to explore teachers' perspectives on the barriers and facilitators to Fundamental Movement Skills (FMS) and physical activity engagement in children living in deprived areas in the UK. A purposive sample of 14 primary school teachers participated in semi-structured focus groups drawn from schools situated in lower SES wards and ethnically diverse areas in Central England. Thematic analysis of transcripts identified multiple and interrelated factors across all levels of the socio-ecological model for barriers to FMS and PA (i.e., intrapersonal, interpersonal, organisational, community and policy). Facilitators at three levels of influence were found (i.e., intrapersonal, interpersonal and organisational). We conclude, barriers and enablers to the PA and FMS in children from ethnically diverse backgrounds living in deprived areas are multifactorial and interrelated. At a school level, initiatives to increase PA and develop the FMS needed to be active are likely to be ineffective unless the barriers are addressed at all levels and considered more holistically with their complexity. Multi-disciplinary solutions are needed across sectors given the range of complex and interrelated factors.

Cross-validation of cut-points in preschool children using different accelerometer placements and data axes.

The present study cross-validated various cut-points to assess physical activity and sedentary behaviour in preschoolers, using hip- and wrist-worn accelerometers and both vertical axis and vector magnitude data. Secondly, we examined the influence of epoch length on time estimates of physical activity and sedentary behaviour. Sixty-four preschoolers (34 girls) wore two accelerometers, on their right hip and dominant wrist, during 1 hour of free play. Preschoolers' activities were observed by two trained researchers. Area under the curve (AUC) was calculated for the receiving operating characteristic (ROC) curves as a measure of precision. AUC ranges were 0.603-0.723 for sedentary behaviour, 0.472-0.545 for light physical activity and 0.503-0.661 for moderate-to-vigorous physical activity (MVPA), indicating poor to fair precision. Percentage of time classified as sedentary behaviour, light or MVPA according to observation and accelerometer data varied largely between cut-points, accelerometer placements and axes. The influence of epoch length on time estimates was minimal across cut-points, except for one hip-based vector magnitude cut-point. Across all accelerometer placements and data axes, no set of cut-points demonstrated adequate precision for sedentary behaviour, light physical activity and MVPA. The highly variable and omnidirectional activity pattern of preschoolers may explain the lack of adequate cut-points.