Tackling physical inactivity and inequalities: implementing a whole systems approach to transform community provision for disabled people and people with long-term health conditions.

BACKGROUND: Physical inactivity is a global public health priority. There are known health and well-being consequences of being inactive, and the benefits of being physically active are well established. However, there are persistent inequalities when it comes to how physically active people are, with disabled people, people living with long-term health conditions, and people residing in areas of socio-economic deprivation being particularly affected. Methods such as whole system approaches (WSAs), which are dynamic, multifaceted, and engage all relevant stakeholders, have gained momentum as an approach to address such complex public health problems. However, evidence relating to the implementation of WSAs to address physical inactivity is lacking. The aim of the Prevention and Enablement Model (PEM) was to take a whole system approach in Essex to encourage and support disabled people and/or individuals living with long-term health conditions to be more active, happier, and to live more independently. METHODS: The aim of this study was to explore the enablers, challenges, and reflections associated with the process of designing and implementing the PEM. Semi-structured interviews (n = 12) were used to collect data from people involved in the PEM's design, implementation and/or delivery. Data was analysed using Braun and Clarke's reflexive thematic analysis. RESULTS: Four themes were identified: (1) Working collaboratively: Specific enablers of time and space were identified as important in the planning and implementation of a WSA (2) Leadership and planning: Distributed and flexible leadership was identified as central to successful implementation (3) Re-orientating practice: Highlighted the transformative potential of a whole system approach and how it contrasts with conventional work practices, and (4) Reflection and learning: Informing ongoing refinements and further implementation of successful system change. CONCLUSIONS: These findings highlight the challenge and complexity of implementing a WSA that involves diverse stakeholders from across adult social care, the NHS, and the third sector. Several important enablers are identified, such as leadership and planning, and the challenges and discomfort that can arise whilst changing systems. Ongoing efforts are required to ensure that different elements of the system collaborate effectively to address inequalities in physical activity participation, through the implementation of a WSA.

Planning engagement with web resources to improve diet quality and break up sedentary time for home-working employees: A mixed methods study.

As home working becomes more common, employers may struggle to provide health promotion interventions that can successfully bridge the gap between employees' intentions to engage in healthier behaviors and actual action. Based on past evidence that action planning can successfully encourage the adoption of healthier behaviors, this mixed-methods study of a web-based self-help intervention incorporated a randomized planning trial that included quantitative measures of engagement and follow-up qualitative interviews with a subsample of participants. Participants either (a) selected a movement plan for incorporating a series of 2-min exercise videos into their work week to break up sedentary time and a balanced meal plan with recipe cards for a week's lunches and dinners or (b) received access to these resources without a plan. Selecting a movement plan was more effective at increasing engagement with the web resources compared to the no-plan condition. In the follow-up interviews, participants indicated that the plan helped to remind participants to engage with the resources and made it simpler for them to follow the guidance for exercises and meals. Ease of use and being able to fit exercises and meals around work tasks were key factors that facilitated uptake of the resources, while lack of time and worries about how colleagues would perceive them taking breaks to use the resources were barriers to uptake. Participants' self-efficacy was associated with general resource use but not plan adherence. Overall, including plans with online self-help resources could enhance their uptake. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Knee extensor force control as a predictor of dynamic balance in healthy adults.

BACKGROUND: Previous research has demonstrated that force control in various muscles of the lower limb (measured according to the magnitude of force fluctuations) explains significant variance in static balance. Given the dynamic nature of many functional activities and sports, assessment of balance and its determinants under dynamic conditions is of importance. RESEARCH QUESTION: Does muscle force control explain significant variance in dynamic balance, as measured using the Y balance test (YBT)? METHODS: YBT performance and knee extensor muscle force control were measured in 28 healthy participants. The YBT involved stance on the right leg and attempting maximal reach with the left leg in the anterior, posteromedial, and posterolateral directions. Force control was assessed during isometric knee extension contractions of the right leg at 10%, 20% and 40% maximal voluntary contraction (MVC) and was quantified according to the magnitude (using the coefficient of variation [CV]), and the temporal structure (using sample entropy, SampEn; and detrended fluctuation analysis α), of force fluctuations. RESULTS: Significant correlations were observed for YBT anterior reach and muscle force CV (r = -0.44, P = 0.02) and SampEn (r = 0.47, P = 0.012) during contractions at 40% MVC. A subsequent regression model demonstrated that muscle force CV and SampEn at 40% MVC significantly explained 54% of variance in YBT anterior reach. Significant correlations were also observed for YBT posteromedial reach and MVC (r = 0.39, P = 0.043) and muscle force CV during contractions at 40% MVC (r = -0.51, P = 0.006). The regression model demonstrated that MVC and muscle force CV at 40% MVC significantly explained 53.9% of variance in YBT posteromedial reach. SIGNIFICANCE: These results are the first to indicate that a moderate amount of variance in dynamic balance can be explained by measures of isometric force control.

The Effect of Breaking Up Sedentary Time with Calisthenics on Neuromuscular Function: A Preliminary Study.

The ageing process results in reduced neuromuscular function. This alongside prolonged sedentary behaviour is associated with decreased muscle strength, force control and ability to maintain balance. Breaking up sedentary time with regular bouts of physical activity has numerous health benefits, though the effects on neuromuscular function are unknown. This study investigated the effect of breaking up sedentary time with calisthenic exercise on neuromuscular function. 17 healthy adults (33 ± 13.1 years), who spent ≥6 h/day sitting, were assigned to a four-week calisthenics intervention (n = 8) or control group (n = 9). The calisthenics intervention involved performing up to eight sets of exercises during the working day (09:00-17:00); with one set consisting of eight repetitions of five difference exercises (including squats and lunges). Before and immediately after the intervention, measures of knee extensor maximal voluntary contraction (MVC) and submaximal force control (measures of the magnitude and complexity of force fluctuations), and dynamic balance (Y balance test) were taken. The calisthenics intervention resulted in a significant increase in knee extensor MVC (p = 0.036), significant decreases in the standard deviation (p = 0.031) and coefficient of variation (p = 0.016) of knee extensor force fluctuations during contractions at 40% MVC, and a significant increase in Y balance test posterolateral reach with left leg stance (p = 0.046). These results suggest that breaking up sedentary time with calisthenics may be effective at increasing muscle strength, force steadiness and dynamic balance all of which might help reduce the effects of the ageing process.

Development of a self-report measure to assess sleep satisfaction: Protocol for the Suffolk Sleep Index (SuSI).

Good sleep is essential for health but there is no consensus on how to define and measure people's understanding of good sleep. To date, people's perceptions of a good night's sleep have been, almost exclusively, conceptualized under the lens of sleep quality, which refers to objective characteristics of good sleep, such as such as ease and time needed to fall asleep, hours of sleep, and physical symptoms during sleep and upon awakening. A related, yet different construct, sleep satisfaction, refers to perceived positive affect about one's sleep experience and has, to date, received little attention. This research focuses on sleep satisfaction, rather than sleep quality, and aims to develop a self-report measure to assess sleep satisfaction in an English adult population. As the measure will be developed in Suffolk, England, and its primary intended users are Suffolk community members, it is labelled the Suffolk Sleep Index (SuSI). The SuSI will draw from principles of community-based participatory research, following a seven-phase developmental process comprising literature review, interviews with Suffolk community members, synthesis of literature review and interview findings, pre-testing, pilot-testing, scale evaluation, and refinement. The present research will also investigate indices related to sleep satisfaction, including the community's general health status, lifestyle factors and socio-economic status. The research will add to the limited, yet emerging body of research on perceived sleep satisfaction and its measurement. To our knowledge, a valid and reliable sleep satisfaction self-report measure has not been developed in the United Kingdom previously.

Operationalization of One Health Burnout Prevention and Recovery: Participatory Action Research-Design of Nature-Based Health Promotion Interventions for Employees.

Burnout is, besides a global, complex phenomenon, a public health issue with negative consequences on personal, organizational, social, and economic levels. This paper outlines the co-design of a novel Nature-based Burnout Coaching intervention, called NABUCO. Due to the complexity of burnout, we propose a One Health approach in healthcare, educational and governmental pilot organizations, to deliver guidelines and protocols for prevention and recovery of burnout. We advocate the inclusion of the salutogenic and mutual healing capacity of nature connectedness, facilitating a positive impact on mental and environmental health. A transdisciplinary Participative Action Research-design resulted in an iterative adaptive cycle of co-design, implementation, and evaluation of NABUCO.

Can Simulated Green Exercise Improve Recovery From Acute Mental Stress?

This exploratory study enhances previous research into green exercise and addresses a gap in the research by exploring the contribution of individual and combined senses in the recovery of mood and stress after a psychological stressor, whilst rigorously controlling exercise intensity. The hypotheses were: (i) recovery of mood and stress from a state of psychological stress would be greater following simulated green exercise compared to rest, (ii) green exercise would facilitate better recovery than exercise alone, (iii) these effects would remain 10 min following intervention, and (iv) visual stimuli alone would enhance recovery from a state of psychological stress compared to sound. Fifty participants were randomly assigned to one of five groups: REST, exercise, exercise with nature sounds, exercise with nature visual and exercise with nature sound and visual. An initial visit to obtain predicted peak power output values and to familiarize participants with the equipment being used was followed by a second visit, where participants experienced one test condition. Baseline measures of heart rate, blood pressure, total mood disturbance (TMD), and perceived stress were taken, before participants completed a stressor based on the Trier Social Stress test. Measures of heart rate and blood pressure were recorded in the last 30 s of the stressor to assess efficacy of the stressor. Immediately post stressor, measures of mood and perceived stress were taken followed by the intervention assigned (one of five described above). Measures of mood and perceived stress were taken again immediately post intervention and 10 min post intervention. Results showed that green exercise improved mood and stress scores more than exercise alone or REST. For both TMD and perceived stress, improvements in all simulated nature conditions were significantly improved compared to REST or exercise alone immediately post intervention. There were no significant changes 10 min post intervention in either mood or perceived stress compared to immediately post intervention values in any of the groups. This study suggests that environmental exercise settings including nature sounds, visual or both combined should be considered as important in the use of exercise as a therapeutic activity or recovery from acute psychological stress.

The Development of Three Questionnaires to Assess Beliefs about Green Exercise.

Green exercise is physical activity that takes place in the presence of natural environments. Despite the promising evidence of the benefits, little is known about how individuals' thoughts and feelings influence participation in green exercise and subsequent outcomes. The aim of the current research was to develop questionnaires using the Theory of Planned Behaviour as a framework that could both directly and indirectly assess attitudes, subjective norms and perceived behaviour control, along with intention toward green exercise. Confirmatory factor analyses confirmed that the indirect, direct, and intention measures all had good overall model fits when tested on a refinement (n = 253) and validation (n = 230) sample. The questionnaires will contribute towards helping to better understanding individuals' beliefs about green exercise, how these influence behaviour, and ultimately to enable the development of effective interventions promoting green exercise.

Effect of breaking up sedentary time with callisthenics on endothelial function.

Periods of prolonged sitting impairs endothelial function in lower limb conduit arteries, which is attenuated with physical activity breaks. The effect of activity breaks on upper limb arteries has not been examined. This study assessed changes in brachial artery endothelial function following either a prolonged sitting period or breaking up this sedentary time by performing sets of callisthenics exercises. Ten healthy participants (6 men) completed 2 conditions in a counterbalanced order: (a) 1-h 26-min sitting, or (b) breaking up this period every 20 min by performing a set of 5 callisthenics exercises. Brachial artery endothelial function was assessed via ultrasound using the flow-mediated dilation (FMD) technique prior to and following each condition, while brachial shear rate (SR) was acquired after each set of callisthenics. There was no significant change in FMD over time (P = 0.09) or between conditions (P = 0.12). Compared to sitting, brachial SR increased following each set of callisthenics, with a significant difference after the third break (Sit: 33.94 ± 12.79 s-1; Callisthenics: 57.16 ± 30.48 s-1, P = 0.02). Alterations in SR in the upper limbs suggest callisthenics may be an effective intervention to break up sedentary time and attenuate the potentially deleterious effects of prolonged sitting on cardiovascular health.

A cross-sectional study examining predictors of visit frequency to local green space and the impact this has on physical activity levels.

BACKGROUND: Lack of physical activity (PA) is a growing public health concern. There is a growing body of literature that suggests a positive relationship may exist between the amount of local green space near one's home and PA levels. For instance, park proximity has been shown to predict PA levels amongst certain populations. However, there is little evidence for the role of relatedness towards nature and perceptions of local green space on this relationship. The aim of this study was to examine, in a National UK sample, whether subjective indices associated with local green space were better predictors of visit frequency to local green space and PA levels compared to objectively measured quantity of local green space. METHODS: A cross-sectional survey was designed. From a random sample, 2079 working age adults responded to an online survey in September 2011. Demographics, self-reported PA, objective measures of the local environment (including local green space, road coverage, and environmental deprivation), were assessed in conjunction with perceptions of local green space and nature relatedness. Quantity of local green space was assessed by cross-referencing respondents' home postcodes with general land use databases. Regression models were conducted to assess which of our independent variables best predicted visit frequency to local green space and/or meeting PA guidelines. In addition, an ordinal regression was run to examine the relationship between visit frequency to local green space and the likelihood of meeting national PA guidelines. RESULTS: Nature relatedness was the strongest predictor for both visit frequency to local green space and meeting PA guidelines. Results show that perceived quality is a better predictor of visit frequency to local green space than objective quantity of local green space. The odds of achieving the recommended amount of PA was over four times greater for people who visited local green space once per week compared to never going (OR 4.151; 95 % CI, 2.40 to 7.17). CONCLUSIONS: These results suggest that perceptions of local green space and nature relatedness play an important role in the relationship between local green space and PA. Considering the known health benefits of PA, our results are potentially important for public health interventions, policy making and environmental planning.

A Lunchtime Walk in Nature Enhances Restoration of Autonomic Control during Night-Time Sleep: Results from a Preliminary Study.

Walking within nature (Green Exercise) has been shown to immediately enhance mental well-being but less is known about the impact on physiology and longer lasting effects. Heart rate variability (HRV) gives an indication of autonomic control of the heart, in particular vagal activity, with reduced HRV identified as a risk factor for cardiovascular disease. Night-time HRV allows vagal activity to be assessed whilst minimizing confounding influences of physical and mental activity. The aim of this study was to investigate whether a lunchtime walk in nature increases night-time HRV. Participants (n = 13) attended on two occasions to walk a 1.8 km route through a built or a natural environment. Pace was similar between the two walks. HRV was measured during sleep using a RR interval sensor (eMotion sensor) and was assessed at 1-2 h after participants noted that they had fallen asleep. Markers for vagal activity were significantly greater after the walk in nature compared to the built walk. Lunchtime walks in nature-based environments may provide a greater restorative effect as shown by vagal activity than equivalent built walks. Nature walks may improve essential recovery during night-time sleep, potentially enhancing physiological health.

Influences of Green Outdoors versus Indoors Environmental Settings on Psychological and Social Outcomes of Controlled Exercise.

This study addressed a methodological gap by comparing psychological and social outcomes of exercise in green outdoors versus built indoors settings, whilst rigorously controlling exercise mode and intensity. The hypotheses were that greater improvements or more desirable values for directed attention, mood, perceived exertion, social interaction time, intention for future exercise behaviour and enjoyment would be associated with outdoors compared to indoors exercise. Following a baseline session, paired participants completed two conditions of 15 min of cycling on an ergometer placed outside in a natural environment and inside in a laboratory setting in a randomized, counter-balanced order. At pre- and post-exercise, directed attention was measured with the digit span backwards task, and mood was assessed with the Profile of Mood States. During the exercise session, visual and verbal interactions were recorded by means of experimenter observations. After each exercise session, participants provided self-reports of their enjoyment of the exercise, perceived exertion and intention for future exercise in the same environment. Social interaction time was significantly greater during outdoors exercise versus indoors; on average, participants engaged in three minutes more social interaction during exercise outdoors compared to indoors. Social interaction time significantly predicted intention for future exercise in the outdoors condition, but did not in the indoor condition. There was a significant time by condition interaction for directed attention. Scores worsened in the indoors condition, but improved in the outdoors condition. There was no statistically-significant time by condition interaction for mood and no significant difference between conditions for either perceived exertion or intention. Taken together, these findings show that exercise in a natural environment may promote directed attention and social interactions, which may positively influence future exercise intentions.

Occlusion of sight, sound and smell during Green Exercise influences mood, perceived exertion and heart rate.

This study's aim was to identify the relative contribution of sight, sound and smell to the Green Exercise effect. It was hypothesised that visual occlusion while exercising in a natural environment would have the greatest diminishing effect on perceived exertion and mood compared to auditory and olfactory occlusion. Twenty-nine healthy participants were randomly assigned to one of the three groups: visual (n = 10), auditory (n = 9) and olfactory occlusion (n = 10). Each performed six, 5-min bouts of exercise alternating between full sensory and occlusion. Rate of perceived exertion (RPE), heart rate (HR) and mood were recorded at the end of each bout. Sensory-occlusion increased mood, RPE and HR; effects were strongest when sounds were blocked but virtually absent when vision was blocked. During sensory occlusion, mood changes were characterised by increased Fatigue and Confusion, and reduced Vigour. Reductions in Tension and Vigour and increases in Fatigue were found during full sensory exercise, consistent with previous research findings.

A repeated measures experiment of school playing environment to increase physical activity and enhance self-esteem in UK school children.

School playtime provides daily opportunities for children to be active outdoors, but only makes small contributions to physical activity (PA) requirements. Natural environments facilitate unstructured PA and children report a preference for play in nature. Thus, play on the school field might encourage children to be more active during playtime. The primary aim of this study was to examine the impact of the school playing environment on children's PA. Descriptive data and fitness were assessed in 25 children aged 8-9 years from a single primary school. Over two consecutive weeks participants were allocated to either play on the school field or playground during playtime. The order of play in the two areas was randomised and counterbalanced. Moderate to vigorous PA (MVPA) was assessed during playtime on the last two days of each week using accelerometers. There was a significant interaction of environment and sex on MVPA during morning play (F(1,22) = 6.27; P<0.05; np2 = 0.222), but not during lunch (P>0.05; np2 = 0.060) or all of playtime combined (P>0.05; np2 = 0.140). During morning play boys were significantly more active than girls on the playground (t(23) = 1.32; P<0.01; n2 = 0.291), but not on the field (P>0.05; n2 = 0.071). For lunch (F(1,22) = 24,11; P<0.001; np2 = 0.523) and all of playtime combined (F(1,22) = 33.67; P<0.001; np2 = 0.616) there was a significant effect of environment. There was also a significant main effect of sex during lunch (F(1,22) = 11.56; P<0.01; np2 = 0.344) and all of playtime combined (F(1,22) = 12.37; P<0.01; np2 = 0.371). MVPA was higher on the field and boys were more active than girls. Play on the field leads to increases in MVPA, particularly in girls. The promising trend for the effect of the natural environment on MVPA indicates that interventions aimed at increasing MVPA should use the natural environment and that schools should encourage greater use of their natural areas to increase PA.

Walks4Work: assessing the role of the natural environment in a workplace physical activity intervention.

OBJECTIVES: The primary aim of this study was to examine the impact of physical activity (PA) in the natural environment (eg, "green exercise") on resting autonomic function in the Walks4Work intervention. A secondary aim was to assess the feasibility of Walks4Work in terms of adherence, change in PA levels, and cardiovascular health parameters. METHODS: In an 8-week randomized control trial, 94 office workers in an international company were allocated to one of three groups: control, nature (NW), or built (BW) lunchtime walking route. Both walking groups were required to undertake two lunchtime walks each week. The NW route centered around trees, maintained grass, and public footpaths. In contrast, the BW consisted of pavement routes through housing estates and industrial areas. Data were collected at baseline and following the intervention. To investigate the impact of the intervention, mixed-design analysis of variance (ANOVA) were performed. RESULTS: A total of 73 participants completed the intervention (drop-out rate of 22%). No difference was observed in resting autonomic function between the groups. Self-reported mental health improved for the NW group only. PA levels increased at the intervention mid-point for all groups combined but adherence to the intervention was low with rates of 42% and 43% within the BW and NW groups, respectively. CONCLUSION: Accompanying a guideline of two active lunchtimes per week with low facilitator input appears inadequate for increasing the number of active lunchtimes and modifying cardiovascular health parameters in an office population. However, this population fell within normal ranges for cardiovascular measures and future research should consider investigating at-risk populations, particularly hypertensive individuals.

The great outdoors: how a green exercise environment can benefit all.

The studies of human and environment interactions usually consider the extremes of environment on individuals or how humans affect the environment. It is well known that physical activity improves both physiological and psychological well-being, but further evidence is required to ascertain how different environments influence and shape health. This review considers the declining levels of physical activity, particularly in the Western world, and how the environment may help motivate and facilitate physical activity. It also addresses the additional physiological and mental health benefits that appear to occur when exercise is performed in an outdoor environment. However, people's connectedness to nature appears to be changing and this has important implications as to how humans are now interacting with nature. Barriers exist, and it is important that these are considered when discussing how to make exercise in the outdoors accessible and beneficial for all. The synergistic combination of exercise and exposure to nature and thus the 'great outdoors' could be used as a powerful tool to help fight the growing incidence of both physical inactivity and non-communicable disease.

Viewing nature scenes positively affects recovery of autonomic function following acute-mental stress.

A randomized crossover study explored whether viewing different scenes prior to a stressor altered autonomic function during the recovery from the stressor. The two scenes were (a) nature (composed of trees, grass, fields) or (b) built (composed of man-made, urban scenes lacking natural characteristics) environments. Autonomic function was assessed using noninvasive techniques of heart rate variability; in particular, time domain analyses evaluated parasympathetic activity, using root-mean-square of successive differences (RMSSD). During stress, secondary cardiovascular markers (heart rate, systolic and diastolic blood pressure) showed significant increases from baseline which did not differ between the two viewing conditions. Parasympathetic activity, however, was significantly higher in recovery following the stressor in the viewing scenes of nature condition compared to viewing scenes depicting built environments (RMSSD; 50.0 ± 31.3 vs 34.8 ± 14.8 ms). Thus, viewing nature scenes prior to a stressor alters autonomic activity in the recovery period. The secondary aim was to examine autonomic function during viewing of the two scenes. Standard deviation of R-R intervals (SDRR), as change from baseline, during the first 5 min of viewing nature scenes was greater than during built scenes. Overall, this suggests that nature can elicit improvements in the recovery process following a stressor.

Walks4work: rationale and study design to investigate walking at lunchtime in the workplace setting.

BACKGROUND: Following recruitment of a private sector company, an 8 week lunchtime walking intervention was implemented to examine the effect of the intervention on modifiable cardiovascular disease risk factors, and further to see if walking environment had any further effect on the cardiovascular disease risk factors. METHODS: For phase 1 of the study participants were divided into three groups, two lunchtime walking intervention groups to walk around either an urban or natural environment twice a week during their lunch break over an 8 week period. The third group was a waiting-list control who would be invited to join the walking groups after phase 1. In phase 2 all participants were encouraged to walk during their lunch break on self-selecting routes. Health checks were completed at baseline, end of phase 1 and end of phase 2 in order to measure the impact of the intervention on cardiovascular disease risk. The primary outcome variables of heart rate and heart rate variability were measured to assess autonomic function associated with cardiovascular disease. Secondary outcome variables (Body mass index, blood pressure, fitness, autonomic response to a stressor) related to cardiovascular disease were also measured. The efficacy of the intervention in increasing physical activity was objectively monitored throughout the 8-weeks using an accelerometer device. DISCUSSION: The results of this study will help in developing interventions with low researcher input with high participant output that may be implemented in the workplace. If effective, this study will highlight the contribution that natural environments can make in the reduction of modifiable cardiovascular disease risk factors within the workplace.

Association between RR interval and high-frequency heart rate variability acquired during short-term, resting recordings with free and paced breathing.

High-frequency (HF) oscillations in RR interval from 0.15-0.40 Hz are widely accepted as a measure of cardiac vagal outflow but the HF/RR relationship appears complex, particularly with longer RR intervals. The aim of this study was to evaluate the HF/RR interval relationship during free and paced breathing. HF power and mean RR interval length were recorded in 150 men and 120 women (mean age 34.5 +/- 11.4) during 5 min of supine rest with either free or paced (12 cycles min(-1)) breathing. Linear and quadratic models were used to assess the relationship between RR interval and the natural logarithm of HF power (lnHF). The RR interval length at which there was no further increase in lnHF was determined as the deflection point. ANCOVA was used to determine differences in the linear regression slopes for lnHF/RR with paced or free breathing. With free breathing (n = 131), the adjusted R(2) was similar between linear (15.3%) and quadratic (17.5%) fits and saturation of lnHF occurred within the recorded RR interval range (1326 ms). With paced breathing (n = 139), adjusted R(2) values were again similar between linear (22.4%) and quadratic (23.2%) fits. The deflection point was outside the range of recorded RR intervals at 1458 ms. ANCOVA showed a significant difference in the slope of the lnHF/RR regression lines between free and paced breathing. The lnHF/RR relationship is weaker when derived from between-subject recordings than from repeated within-subject samples. lnHF/RR showed evidence of saturation at approximately 45 bpm with free breathing. With paced breathing, a deflection in lnHF was found outside the recorded RR interval range ( approximately 41 bpm). Paced breathing creates a stronger lnHF/RR relationship. The slope of the lnHF/RR regression line with paced breathing is significantly different from that observed with free breathing. It appears that lnHF is a valid index of vagal outflow, except in subjects with very low heart rates. Paced breathing data collection protocols appear preferable.

Twenty-metre shuttle run test performance of English children aged 11-15 years in 2007: comparisons with international standards.

Recent international normative data for the 20-m shuttle-run test demonstrated a below-average performance index for UK children. The aims of the present study were to create an international comparison of 20-m shuttle-run test performance in a sample of English children and to identify age- and sex-specific differences in test performance. Mass, stature, body mass index, and 20-m shuttle-run test performance were measured in 2041 children aged 11-15 years (963 boys, 1078 girls). Performance was expressed as maximum running velocity and a performance index was created by generating z-scores. The shuttle-run test performance index was higher than the existing published value (-0.046, 95% confidence interval [CI] -0.070 to -0.022) for all children (0.061, 95% CI = 0.006 to 0.115), for boys (0.075, 95% CI = -0.022 to 0.171), and for girls (0.048, 95% CI = -0.010 to 0.106). Boys' relative performance increased significantly (F = 4.43, P = 0.002) throughout the measured age range, whereas girls' relative performance tended to decrease (F = 1.98, P = 0.096). The results were favourable when compared with existing values. Differences in performance index may be due to the different geographical areas from which present and past samples were drawn. Reasons for differences in the performance indices between boys and girls warrant further investigation.