The effects of an enhanced quality Physical Education programme on the physical activity levels of Grade 7 learners in Potchefstroom,South Africa

Background: The absence of Physical Education (PE) from the South African school curriculum before its reintroduction in recent years contributed to health concerns regarding the low physical activity (PA) levels of children and adolescents in South Africa.

Purpose: This study evaluated the effects of a once-a-week enhanced quality PE programme on the PA levels of South African Grade 7 learners.

Methods: Using a pre-test and post-test control-group design, 110 Grade 7 learners aged 12–13 years (experimental school, n?=?40; control schools, n?=?70) from two primary schools in Potchefstroom, South Africa, were studied. They participated in a 12-week PE intervention programme based on the guidelines of the South African Curriculum and Assessment Policy Statement, which allocates one hour per week to PE teaching. The intervention included five quality-enhancing components, namely well-trained teachers, homework activities, a reward system, hand-made apparatus and the monitoring of activity intensity. In the experimental school, 40 learners were randomly assigned from the total Grade 7 class (n?=?124) to the experimental group, while two control groups (n?=?37 and n?=?33) were used, one from the same school as the experimental school and the other from a different school. Additionally, to control for PE teacher interaction effect, the experimental group was divided into 4 experimental sub-groups of 10 learners each, which were taught by 4 different PE teachers, and the pre-test and post-test data of these experimental sub-groups were also analysed. Children's PA levels were measured before and after the intervention using a validated Children's Leisure Activities Study Survey questionnaire. The Kruskal–Wallis and Wilcoxon signed-rank tests were used to evaluate the effects of the intervention programme.

Results: No significant differences were found within the experimental group between the 4 experimental sub-groups and between the 2 control groups at pre- and post-test measurements (p?>?.05). There was a significant effect for the experimental group as a whole, as results of the total experimental group showed statistically significant increases in moderate PA (ES?=?0.47; p?=?.014), vigorous PA (ES?=?0.48; p?=?.012) and total PA (ES?=?0.51; p?=?.008) as well as decreases in sedentary behaviours (ES?=?0.39; p?=?.041) after the 12-week intervention programme, whereas no significant changes were found in the control group. Statistically significant improvements were also found in all 4 experimental sub-groups between pre- and post-tests for the time spent in moderate PA (p?=?.028–.05; ES?=?0.23–0.64), vigorous PA (p?=?.018–.036; ES?=?0.23–0.63), total PA (p?=?.017–.05; ES?=?0.30–0.68) and sedentary time (p?=?.014–.049; ES?=?0.26–0.66), whereas no marked changes were observed among the two control groups, indicating no PE teacher interaction effect on the results.

Conclusions: The enhanced quality PE programme can be used as a valuable framework for PE implementation targeted at promoting learners’ PA levels, even in the presence of restricted time allocation, and limited teaching and learning resources.     

Effects of movement velocity and training frequency of resistance exercise on functional performance in older adults: a randomised controlled trial

Objectives: To investigate the effects that high-velocity, low-load (HVLL) and low-velocity, high-load (LVHL) resistance exercise, performed once or twice-weekly, have on indices of functional performance (primary outcome), maximal strength, and body composition (secondary outcomes) in older adults.

Methods: In a randomised, controlled, multi-armed, parallel design, 54 moderately-highly active, but resistance exercise naïve older adults (aged 60–79 years), attended baseline and post-10-week intervention assessment sessions. Physical and functional assessments were completed, and predicted one-repetition maximums (1-RM) were obtained for eight exercises. Participants were then randomised into one of five conditions: HVLL once-weekly (HVLL1: n?=?11) or twice-weekly (HVLL2: n?=?11), LVHL once-weekly (LVHL1: n?=?10) or twice-weekly (LVHL2: n?=?11), no-exercise control condition (CON: n?=?11). The HVLL conditions completed 3 sets of 14 repetitions at 40% 1-RM and the LVHL conditions, 3 sets of 7 repetitions at 80% 1-RM. In total, 50 participants completed all testing and were included in analyses.

Results: Only LVHL2 improved 30-sec chair stand performance (p?=?.035; g?=?0.89), arm curls (p?=?.011; g?=?1.65) and grip-strength (p?=?.015; g?=?0.34) compared to CON. LVHL2 improved maximal strength compared to CON for 7/8 exercises (p?p?Conclusion: Possibly due to the lower intensity nature of the HVLL conditions, LVHL, twice-weekly was most beneficial for improving functional performance and strength in moderately-highly active older adults. Therefore, we recommend that exercise professionals ensure resistance exercise sessions have sufficient intensity of effort and volume, in order to maximise functional performance and strength gains in older adults.     

Are professional young rugby league players eating enough? Energy intake,expenditure and balance during a pre-season

Abstract

Due to the unique energetic demands of professional young collision sport athletes, accurate assessment of energy balance is required. Consequently, this is the first study to simultaneously investigate the energy intake, expenditure and balance of professional young rugby league players across a pre-season period. The total energy expenditure of six professional young male rugby league players was measured via doubly labelled water over a fourteen-day assessment period. Resting metabolic rate was measured and physical activity level calculated. Dietary intake was reported via Snap-N-Send over a non-consecutive ten-day assessment period, alongside changes in fasted body mass and hydration status. Accordingly, energy balance was inferred. The mean (standard deviation) difference between total energy intake (16.73 (1.32) MJ^.day^?1) and total energy expenditure (18.36 (3.05) MJ^.day^?1) measured over the non-consecutive ten-day period was unclear (?1.63 (1.73) MJ^.day^?1; ES?=?0.91?±?1.28; p?=?0.221). This corresponded in a most likely trivial decrease in body mass (?0.65 (0.78) kg; ES?=?0.04?±?0.03; p?=?0.097). Resting metabolic rate and physical activity level across the fourteen-day pre-season period was 11.20 (2.16) MJ^.day^?1 and 1.7 (0.2), respectively. For the first time, this study utilises gold standard assessment techniques to elucidate the distinctly large energy expenditures of professional young rugby league players across a pre-season period, emphasising a requirement for equally large energy intakes to achieve targeted body mass and composition adaptations. Accordingly, it is imperative that practitioners regularly assess the energy balance of professional young collision-sport athletes to ensure their unique energetic requirements are achieved.     

Body dissatisfaction in normal weight children – sports activities and motives for engaging in sports

Body dissatisfaction is a phenomenon that may already occur in childhood and is linked to a variety of psychosocial risks. As the role of physical activity in the context of body dissatisfaction is still ambivalent, a cross-sectional study with 602 normal weight children (50.2% girls; M_age?=?9.23 years; SD?=?0.79) was conducted. The children filled in the MoMo-Questionnaire, including items about their physical activities and motives for being physically active, as well as Bender’s Body Esteem and Muscularity Concern Scale with the three subscales “body satisfaction”, “weight and shape concerns”, and “muscularity concerns”. Independent t-tests revealed that girls were less worried about muscularity than boys (M_girls?=?1.94, SD_girls?=?1.11 vs. M_boys?=?3.12, SD_boys?=?1.43; t(560)?=?11.33, p?d?=?0.92), whereas girls showed greater weight and shape concerns than boys (M_girls?=?2.24, SD_girls?=?0.97 vs. M_boys?=?2.05, SD_boys?=?0.92; t(549)?=?2.32, p?=?.02, d?=?0.20). In boys, physical activity is associated with less muscularity, weight, and shape concerns. Body satisfaction increases with health and fitness motives. In girls, the role of physical activity is ambivalent: girls who engage in sports do not differ in body dissatisfaction from non-active girls. In sportive girls, weight and shape concerns increased with more health and fitness motives. Finally, the study provides first insights into body dissatisfaction and the different role of physical activity in boys and girls in childhood.     

Combined training,FNDC5/irisin levels and metabolic markers in obese men: A randomised controlled trial

The effects of training on FNDC5/irisin and its association with fitness and metabolic marker improvements induced by training have been poorly investigated in humans. Thus, the present study assessed the effects of combined training (CT) on FNDC5/irisin levels, metabolic markers and fitness adaptations in obese men. Middle-age obese men (age 49.13?±?5.75, body mass index (BMI) 30.86?±?1.63) were randomly distributed in the CT group (n?=?12) and control group (CG n?=?10). The CT consisted of strength followed by aerobic training, 3 times/week, for 24 weeks. Body composition, physical fitness, plasma FNDC5/irisin, biochemical markers and metabolic scores/index were evaluated. CT maintained FNDC5/irisin levels (µg/mL) (pre: 4.15?±?0.32, post: 4.21?±?0.32; p?=?.96) and improved body composition, metabolic and physical fitness markers. In the CG, decreased FNDC5/irisin (µg/mL) (pre: 4.36?±?0.23, post: 3.57?±?0.94; p?=?.01) and reduced strength (supine exercise/kg) (pre: 71?±?14.7, post: 60.1?±?14.05; p?<?.01) were observed, along with a trend to increase HOMA-IR (pre: 2.63?±?1.11, post: 3.14?±?1.27; p?=?.07) and other indicators of metabolic deterioration. An inverse correlation was found between the change (Δ%) in levels of FNDC5/irisin and Δ% glucose, Δ% total cholesterol, Δ% triglycerides and Δ% waist circumference, in addition to a positive relation with Δ% muscle strength. In conclusion, CT maintained FNDC5/irisin levels and provided metabolic and fitness benefits. The correlation between FNDC5/irisin changes and metabolic parameters, as well as the FNDC5/irisin reduction associated with fitness and metabolic worsening in the CG, suggests a relationship between FNDC5/irisin and a healthy metabolic status in humans.     

The effects of high resistance–few repetitions and low resistance–high repetitions resistance training on climbing performance

The aim of the study was to compare the effects of different strength training intensities on climbing performance, climbing-specific tests and a general strength test. Thirty lower grade and intermediate-level climbers participated in a 10-week training programme. The participants were randomized into three groups: high resistance–few repetitions training groups (HR-FR), low resistance–high repetitions training groups (LR-HR) and a control group (CON) which continued climbing/training as usual. Post-testing results demonstrated statistical tendencies for climbing performance improvements in the HR-FR and LR-HR (p?=?0.088–0.090, effect size?=?0.55–0.73), but no differences were observed between the groups (p?=?0.950). For the climbing-specific tests, no differences were observed between the groups (p?=?0.507–1.000), but the HR-FR and LR-HR improved their time in both Dead-hang (p?=?0.004–0.026) and Bent-arm hang (p?<?0.001–0.002). The HR-FR and LR-HR improved their 12RM strength in pull-down (p?≤?0.001), but not the CON group (p?=?0.250). No differences were observed in the CON group in any of the tests (p?=?0.190–0.596) with the exception of improvement in Bent-arm Hang (p?=?0.018). The training groups reduced their climbing sessions during the intervention compared to the CON group (p?=?0.057–0.074). In conclusion, HR-FR and LR-HR training programmes demonstrated an 11% and 12% non-significant improvement in climbing performance despite a 50% reduction in climbing sessions, but improved the results in strength and climbing-specific tests. None of the training intensities was superior compared to the others.     

Die Körperzusammensetzung von Hobbygamern im Vergleich zu deutschlandweit erhobenen Referenzdaten

About two thirds of adults in Germany are overweight or obese. While an increase in the consumption of high-calorie food is considered the main cause, the influence of various forms of sedentary activities is still controversially discussed. The aim of the present study is to compare the body composition of hobby gamers with reference data collected throughout Germany and to examine the effects of intensive use of computer games (gaming) on body composition. A total of 68 male participants of a computer game event aged 18–46 years (27.9 years; 180.1?cm; 83.5?kg; BMI 25.7) were examined for fat mass, body cell mass, extracellular mass, body water and phase angle using bioelectrical impedance analysis (BIA, Nutriguard MS type, data input). Ten test persons were retested by means of segmental 8?electrode BIA after a 24?h interval during their visit to the event. As a reference sample, data from 278 male adults of the same age (27.9 years, 179.4?cm; 78.8?kg; BMI 24.5) were collected in 168 locations throughout Germany. The hobby gamers reported on average 37.1?h screen media usage per week. Compared to the reference sample, they showed a slightly higher body cell mass index (p?<?0.01, T?=?4.07), but no differences in fat mass index (p?=?0.96, T?=?0.05) and phase angle (p?=?0.90, T?=?0.12). A significant increase in body water (T₀: 48.2?l, T₀₊₂₄?_h: 49.3?l; p?=?0.04, T?=?2.39) and decrease in the phase angle of the lower extremities (T₀:?7.40, T₀₊₂₄?_h: ?6.85; p?<?0.01, T?=?5.40) was observed in the 24?h retest. Compared to the reference data collected throughout Germany, hobby gamers show no differences in health-relevant parameters of body composition. Nevertheless, after intensive gaming, a short-term increase in the amount of extracellular water in the lower extremities was found. Due to these disturbances in the water balance, the consequent execution of movement breaks during gaming is important.     

Bone mass in girls according to their BMI,VO2 max,hours and years of practice

The accumulation of bone mass during puberty is related with bone health in adulthood. This accumulation is influenced by diverse factors such as body mass index (BMI), maximal oxygen uptake (VO₂ max), hours of training and years of sport practice. For this reason, the objective of this study is to analyse the influence of these variables on bone mass in young female athletes. The sample is formed of 120 healthy girls with ages between 9 and 13 (11.32?±?1.6?years old), divided into two groups depending on their BMI, VO₂ max, hours of training and years of sport practice. The participants completed a series of tests to evaluate level of sexual development, body composition (fat mass, lean mass and bone mass) and physical condition. The results show higher values of total lean mass, total fat mass and percentage of body fat in the groups with higher BMI in prepubertal girls and pubertal girls (p?2 max, in the prepubertal group, girls with lower VO₂ max had higher values of total fat mass (p?p?2 max also showed a higher total fat mass (p?相似文献   

An integrated curriculum approach to increasing habitual physical activity in deprived South Asian children

Integrating physical activity (PA) within a school curriculum is a promising approach for increasing PA in children. To date, no research has examined its effectiveness in increasing the low levels of PA witnessed in deprived South Asian (SA) children. The study aims to ascertain whether an integrated school-based curriculum and pedometer intervention could increase PA in children from deprived SA backgrounds. Following ethical approval and informed consent, 134 deprived SA children (63 boys, 71 girls, control (n?=?40, mean age?=?11.12 years, SD?=?0.32 years) and intervention (n?=?94, mean age?=?9.48 years, SD?=?0.62 years)) from a primary school in England, UK, completed a 6-week integrated PA intervention based on virtually walking from their school (middle of the country) to the coast and back (March–July 2013). Habitual PA was determined at baseline and post 6 weeks intervention for both groups, and determined weekly during the intervention in the experimental group. The results indicated that average daily steps were significantly higher at post 6 weeks compared to baseline for the intervention group (intervention mean change?=?8694 steps/day, SD?=?7428 steps/day vs. control mean change?=??1121 steps/day, SD?=?5592 steps/day, 95% CI of difference, 6726–7428 steps/day, P?=?.001, d?=?1.76). In addition, significant decreases in BF% and waist circumference were observed in the intervention group post 6 weeks (mean change for BF%?=??4.5%, mean change for WC?=??1.7?cm, P?=?.001). School-based integrated curriculum and pedometer interventions provide a feasible and effective mechanism for increasing habitual PA in primary school children from deprived SA backgrounds.     

Impact of a pedometer-based goal-setting intervention on children’s motivation,motor competence,and physical activity in physical education

Background: School physical education (PE) programs provide a prime environment for interventions that attempt to develop school-aged children’s motor competence and overall physical fitness, while also stimulating competence motivation to engage in physical activity during childhood. It is generally recognized that a pedometer-based intervention strategy combined with a goal-setting strategy may be effective in increasing physical activity participation among school-aged children. The purpose of this study was to evaluate the impact of an 8-week pedometer-based goal-setting intervention on children’s motivation in PE, motor competence, and physical activity.

Methods: A pretest–posttest comparison group design was used with the 8-week intervention (3 days/week for 24 sessions). Participants were 273 (boys?=?136, girls?=?137) students recruited from 3 elementary schools in the US. Classes in each school were randomly allocated to three experimental conditions: (1) an intervention group with a personalized pedometer weekly target to reach in their PE class (N?=?110), (2) an intervention group with the fixed pedometer target range to reach in each PE class based on the recommended criteria (N?=?90), or (3) a control group without intervention (N?=?73).

Analysis/results: The factorial repeated measures MANOVA indicated significant multivariate effects for the group [F(6, 528)?=?12.954, p?Post hoc analyzes showed that both experimental groups had significantly higher expectancy-value beliefs, motor competence, and physical activity compared to the control group (p?Conclusions: Health practitioners should be aware that goal-directed action can contribute to school students’ PE-related achievement motivation, motor competence, and achieving the recommended 60?min of moderate-to-vigorous physical activity.     

The association of major patterns of physical activity,sedentary behavior and sleeping with mortality in older adults

Objective: To identify major patterns of physical activity (PA), sedentary behavior (SB) and sleeping (all self-reported), and their association with long-term mortality.

Methods: Cohort of 2,851 individuals aged ≥ 60 from Spain. Mortality was ascertain from 2003 up to July 2013. Patterns of PA, SB and sleeping were identified by factor analysis.

Results: During follow-up, 1,145 deaths occurred. The first pattern, named “sedentary and non-active pattern”, was characterized by long sleeping or lying time, and not doing even light PA (household chores or walking). The second pattern was named “active and non-sedentary pattern”, and was characterized long time devoted to vigorous activities, long walking time, and short seating time. Compared to those in the first quartile of the “sedentary and non-active pattern”, those in the highest quartile showed a 71% higher mortality (HR: 1.71; 95%CI: 1.42–2.07; p-trend:<0.001); it corresponds to being 6-year older. By contrast, being in the highest versus the lowest quartile of the “active and non-sedentary pattern” was associated with a 32% lower mortality (HR: 0.68: 0.57–0.82; p-trend:<0.001); it corresponds to being 4-year younger.

Conclusion: The “sedentary and non-active” pattern had a large impact on mortality. The “active and non-sedentary” pattern showed an opposite and slightly lower association.     

Effects of Pilates on fall risk factors in community-dwelling elderly women: A randomized,controlled trial.

Abstract

Objective: the main objective was to analyze the effects that an exercise programme based on the Pilates method would have on balance confidence, fear of falling, and postural control among women ≥60 years old. Methods: a total of 110 women (69.15?±?8.94 years) participated in this randomized, controlled trial that took place in Jaén (Spain). The participants were randomly assigned to either a control group (n?=?55), which received no intervention, or to a Pilates group (n?=?55), which carried out an exercise programme based on the Pilates method in 60-minute sessions for 12 weeks. The Falls Efficacy Scale-International and the activity-specific balance confidence scale were respectively used to assess fear of falling and balance confidence in performing activities of daily living. Postural control was evaluated using a stabilometric platform. Results: Regarding balance confidence, the Pilates group showed higher values compared to the control group (77.52?±?18.27 vs 72.35?±?16.39, Cohen’s d?=?0.030). Women in the Pilates group showed lower fear of falling, compared to those of the control group (22.07?±?5.73 vs 27.9?±?6.95, Cohen’s d?=?0.041). Finally, concerning static balance, participants of the Pilates group experienced statistically significant improvements on the velocity and anteroposterior movements of the centre of pressure with eyes open and closed respectively (Cohen’s d?=?0.44 and 0.35 respectively). Conclusion: A 12-week Pilates training programme has beneficial effects on balance confidence, fear of falling and postural stability, in elderly women.     

Longer-term effects of minimalist shoes on running performance,strength and bone density: A 20-week follow-up study*

This study investigated whether male runners improve running performance, running economy, ankle plantar flexor strength, and alter running biomechanics and lower limb bone mineral density when gradually transitioning to using minimalist shoes for 100% of weekly running. The study was a planned follow-up of runners (n?=?50) who transitioned to minimalist or conventional shoes for 35% of weekly structured training in a previous 6-week randomised controlled trial. In that trial, running performance and economy improved more with minimalist shoes than conventional shoes. Runners in each group were instructed to continue running in their allocated shoe during their own preferred training programme for a further 20 weeks while increasing allocated shoe use to 100% of weekly training. At the 20-week follow-up, minimalist shoes did not affect performance (effect size: 0.19; p?=?0.218), running economy (effect size: ≤?0.24; p?≥?0.388), stride rate or length (effect size: ≤?0.12; p?≥?0.550), foot strike (effect size: ≤?0.25; p?≥?0.366), or bone mineral density (effect size: ≤?0.40; p?≥?0.319). Minimalist shoes increased plantar flexor strength more than conventional shoes when runners trained with greater mean weekly training distances (shoe*distance interaction: p?=?0.036). After greater improvements with minimalist shoes during the initial six weeks of a structured training programme, increasing minimalist shoe use from 35% to 100% over 20 weeks, when runners use their own preferred training programme, did not further improve performance, running economy or alter running biomechanics and lower limb bone mineral density. Minimalist shoes improved plantar flexor strength more than conventional shoes in runners with greater weekly training distances.     

Do the physical and environment PETTLEP elements predict sport imagery ability?

The present study aimed to examine whether physical and environment elements of PETTLEP imagery relate to the ability to image five types of sport imagery (i.e. skill, strategy, goal, affect and mastery). Two hundred and ninety participants (152 males, 148 females; M_age?=?20.24 years, SD?=?4.36) from various sports completed the Sport Imagery Ability Questionnaire (SIAQ), and a set of items designed specifically for the study to assess how frequently participants incorporate physical (e.g. ‘I make small movements or gestures during the imagery’) and environment (e.g. ‘I image in the real training/competition environment’) elements of PETTLEP imagery. Structural equation modelling tested a hypothesised model in which imagery priming (i.e. the best fitting physical and environment elements) significantly and positively predicted imagery ability of the different imagery types (skill, β?=?0.38; strategy, β?=?0.23; goal, β?=?0.21; affect, β?=?0.25; mastery, β?=?0.22). The model was a good fit to the data: χ² (174)?=?263.87, p?<?.001, CFI?=?.96, TLI?=?.95, SRMR?=?.09, RMSEA?=?0.05 (90% CI?=?0.03–0.05). Findings displayed that priming imagery with physical and environment elements is associated with better skill, strategy, goal, affect and mastery imagery ability. The findings extend models of imagery use by indicating that how athletes images may influence their imagery ability.     

In-season changes in ventricular morphology and systolic function in adolescent female athletes

Purpose: To evaluate the influence of physical maturity on the changes in ventricular morphology and function with sport training in female youth athletes.

Methods: Thirty-two female athletes (age 13–18 years) underwent height and weight measurement and 2-D echocardiographic evaluation immediately prior to, and following, a 20-week soccer season. Pre- and post-season left ventricular end-diastolic diameter (LVEDD), end-diastolic volume (LVEDV), ejection fraction (LVEF), stroke volume (LVSV), mass (LVM), and posterior wall thickness (LVPWT), right ventricular end-diastolic diameter (RVEDD), end-diastolic area (RVEDA), and fractional area change (RVFAC), and interventricular septal thickness (IVST) were compared. In-season change in each variable was compared across pre-season hours of vigorous physical activity (0–1, 2–3, >3 hours).

Results: Significant increases were identified in LVEDV (51.3?±?10.4?v 56.4?±?9.6?ml/m², p?=?0.001) and RVEDA (10.5?±?1.9?v 11.3?±?2.5?cm²/m², p?=?0.040), but not LVEDD, LVM, LVPWT, LVSV, RVEDD, RVEDA, RVFAC, or IVST (p?>?0.05 for all). In-season changes in echocardiographic variables did not differ across hours of pre-season vigorous physical activity (p?>?0.05 for all).

Conclusion: Among female adolescent soccer players, in-season training elicits changes in resting ventricular volume, but not wall thickness or systolic function. These adaptations do not appear to be influenced by pre-season physical activity level.     

Sedentary time and vigorous physical activity are independently associated with cardiorespiratory fitness in middle school youth

Abstract

The purpose of this cross-sectional study was to examine the relationship between objectively measured physical activity, sedentary time, and cardiorespiratory fitness in a diverse sample of youth. Participants were recruited from three middle schools and completed assessments of height, weight, cardiorespiratory fitness, and wore an accelerometer for a minimum of four days. Hierarchical general linear models controlling for age, body mass index (BMI) percentile, and sex were used to evaluate the association of time (minutes per day) spent sedentary, and in moderate physical activity and vigorous physical activity with cardiorespiratory fitness (i.e., heart rate response [beats per minute], dependent variable). Results indicated age (β = –0.16, P < 0.05), BMI percentile (β = 0.33, P <0.05), being male (β = 0.17, P < 0.05), sedentary time (β = 0.11, P <0.05), moderate (β = –0.03, P > 0.05) and vigorous (β = –0.22, P < 0.05) physical activity explained 29% of the variance in cardiorespiratory fitness. Evaluation of fitness among high sedentary/high vigorous, high sedentary/low vigorous, low sedentary/low vigorous, and low sedentary/high vigorous groups (defined by the median split) showed that high levels of vigorous activity removed the detrimental effect of high levels of sedentary time on cardiorespiratory fitness. These analyses suggest that the negative impact of sedentary time can be mitigated by engaging in vigorous activity.     

Interval running with self-selected recovery: Physiology,performance, and perception

This study (1) compared the physiological responses and performance during a high-intensity interval training (HIIT) session incorporating externally regulated (ER) and self-selected (SS) recovery periods and (2) examined the psychophysiological cues underpinning SS recovery durations. Following an incremental maximal exercise test to determine maximal aerobic speed (MAS), 14 recreationally active males completed 2 HIIT sessions on a non-motorised treadmill. Participants performed 12?×?30?s running intervals at a target intensity of 105% MAS interspersed with 30?s (ER) or SS recovery periods. During SS, participants were instructed to provide themselves with sufficient recovery to complete all 12 efforts at the required intensity. A semi-structured interview was undertaken following the completion of SS. Mean recovery duration was longer during SS (51?±?15?s) compared to ER (30?±?0?s; p?d?=?1.46?±?0.46). Between-interval heart rate recovery was higher (SS: 19?±?9?b?min^?1; ER: 8?±?5?b?min^?1; p?d?=?1.43?±?0.43) and absolute time ≥90% maximal heart rate (HR_max) was lower (SS: 335?±?193?s; ER: 433?±?147?s; p?=?.075; d?=?0.52?±?0.39) during SS compared to ER. Relative time ≥105% MAS was greater during SS (90?±?6%) compared to ER (74?±?20%; p?d?=?0.87?±?0.40). Different sources of afferent information underpinned decision-making during SS. The extended durations of recovery during SS resulted in a reduced time ≥90% HR_max but enhanced time ≥105% MAS, compared with ER exercise. Differences in the afferent cue utilisation of participants likely explain the large levels of inter-individual variability observed.     

Environmental correlates of sedentary behaviors and physical activity in Chinese preschool children: A cross-sectional study

ObjectiveThis cross-sectional study examined environmental correlates of sedentary behavior (SB) and physical activity (PA) in preschool children in the urban area of Tianjin, China.MethodsData were collected from the Physical Activity and Health in Tianjin Chinese Children study, involving healthy children 3–6 years old and their families. In all children (n = 980), leisure-time SB (LTSB) and leisure-time PA (LTPA) were reported in min/day by parents. In a subgroup (n = 134), overall sedentary time, light PA, and moderate-to-vigorous PA (MVPA) were objectively measured using ActiGraph accelerometry (≥3 days, ≥10 h/day). Environmental correlates were collected using a questionnaire that included home and neighborhood characteristics (e.g., traffic safety, presence of physical activity facilities) and children's behaviors. Potential correlates were identified using linear regression analysis.ResultsMultiple linear regression analysis showed that “having grandparents as primary caregivers” (βs and 95% confidence intervals (95%CIs) for overall sedentary time: 29.7 (2.1–57.2); LTSB (ln): 0.19 (0.11–0.28)) and “having a television (for LTSB (ln): 0.13 (0.00–0.25)) or computer (for LTSB (ln): 0.13 (0.03–0.23)) in the child's bedroom” were both associated with higher SB. Furthermore, “having grandparents as primary caregivers” was associated with less MVPA (β (95%CI): ?7.6 (?14.1 to ?1.2)), and “active commuting to school by walking” correlated with more MVPA (β (95%CI): 9.8 (2.2–17.4)). The path model showed that “more neighborhood PA facilities close to home” was indirectly related to higher LTPA (ln), which was partly mediated by “outdoor play” (path coefficients (95%CI): 0.005 (0.002–0.008)) and “going to these facilities more often” (path coefficients (95%CI): 0.013 (0.008–0.018)). Traffic safety was not a correlate.ConclusionFamily structure and media exposure in the home maybe important factors in shaping preschoolers’ PA patterns. Built environmental correlates could indirectly influence preschoolers’ LTPA through parental help with engaging in active behaviors.     

Physical activity estimated by the bone-specific physical activity questionnaire is also associated with cardiovascular risk

The nature of physical activity that benefits bone is traditionally thought to differ from that benefiting cardiovascular health. Accordingly, exercise recommendations for improving bone health and cardiovascular health are largely incongruent. Our aim was to determine the associations between high-impact physical activity participation and both cardiovascular disease risk factors and bone mass. We recruited 94 men and women (age 34.0?±?13.3 years) to undergo measures of cardiovascular disease risk (BMI, total cholesterol, fasting blood glucose, waist-to-hip ratio, and mean arterial pressure) and dual-energy X-ray absorptiometry (DXA XR-800, Norland) measures of bone mass (femoral neck, lumbar spine, and whole body BMD) and body composition (whole body lean mass and fat mass). Physical activity participation was estimated using the bone-specific physical activity questionnaire (BPAQ). Those in the upper tertile for current BPAQ score exhibited lower total cholesterol, waist-to-hip ratio, and mean arterial pressure than those in the lower tertiles (P?r?=??0.49 to 0.29, P?P?=?0.008), with BPAQ score predicting 6% of the variance in BMD (P?=?0.02). We conclude that high-impact physical activity as captured by the BPAQ may be beneficial for both bone health and for attenuating cardiovascular disease risk.     

Using compositional data analysis to explore accumulation of sedentary behavior,physical activity and youth health

Purpose:The study aimed to describe youth time-use compositions,focusing on time spent in shorter and longer bouts of sedentary behavior and physical activity(PA),and to examine associations of these time-use compositions with cardiometabolic biomarkers.Methods:Accelerometer and cardiometabolic biomarker data from 2 Australian studies involving youths 7-13 years old were pooled(complete cases with accelerometry and adiposity marker data,n=782).A 9-component time-use composition was formed using compositional data analysis:time in shorter and longer bouts of sedentary behavior;time in shorter and longer bouts of light-,moderate-,or vigorous-intensity PA;and"other time"(i.e.,non-wear/sleep).Shorter and longer bouts of sedentary time were defined as<5 min and>5 min,respectively.Shorter bouts of light-,moderate-,and vigorous-intensity PA were defined as<1 min;longer bouts were defined as≥1 min.Regression models examined associations between overall time-use composition and cardiometabolic biomarkers.Then,associations were derived between ratios of longer activity patterns relative to shorter activity patterns,and of each intensity level relative to the other intensity levels and"other time",and cardiometabolic biomarkers.Results:Confounder-adjusted models showed that the overall time-use composition was associated with adiposity,blood pressure,lipids,and the summary score.Specifically,more time in longer bouts of light-intensity PA relative to shorter bouts of light-intensity PA was significantly associated with greater body mass index z-score(zBMI)(β=1.79;SE=0.68)and waist circumference(β=18.35,SE=4.78).When each activity intensity was considered relative to all higher intensities and"other time",more time in light-and vigorous-intensity PA,and less time in sedentary behavior and moderate-intensity PA,were associated with lower waist circumference.Conclusion:Accumulating PA,particularly light-intensity PA,in frequent short bursts may be more beneficial for limiting adiposity compared to accumulating the same amount of PA at these intensities in longer bouts.