Maturation-related adaptations in running speed in response to sprint training in youth soccer players

Objectives This study investigated the effects of a previously recommended dose of sprint training (ST) in young male soccer players of differing maturity status. Design Quasi-experimental design. Methods Male soccer players from two professional academies were divided into Pre-PHV (Training: n = 12; Control: n = 13) and Mid-PHV (Training: n = 7; Control = 10) groups. The training groups completed 16 sprints of 20 m with 90 seconds recovery, once per week. Results Between-group effect sizes (ES) were substantially larger in Pre-PHV (10 m [1.54, CI: 0.74 to 2.23]; 20 m [1.49, CI: 0.75 to 2.23]; 5-10-5 [0.92, CI: 0.23 to 1.61]) than in Mid-PHV (10 m [-0.00, CI: −0.81 to 0.81]; 20 m [-0.12, CI: −0.93 to 0.69]; 5-10-5 [-0.41, CI: −1.22 to 0.41]). Within-group effects demonstrated a similar, though less accentuated, trend which revealed ST to be effective in both Pre-PHV (10 m [0.44, CI: −0.24 to 1.12]; 20 m [0.45, CI: −0.23 to 1.13]; 5-10-5 [0.69, CI: 0.00 to 1.38]) and Mid-PHV (10 m [0.51, CI: −0.38 to 1.40]; 20 m [0.33, CI: −0.56 to 1.21]; 5-10-5 [0.43, CI: −0.46 to 1.32]). Conclusions ST, in the amount of 16 sprints over 20 m with a 90 s rest, may be more effective in Pre-PHV youths than in Mid-PHV youths

Effects of reallocating time in different activity intensities on health and fitness: a cross sectional study

BACKGROUND: The effects of replacing time in specific activity categories for other categories (e.g. replacing sedentary time with light activity) on health and fitness are not well known. This study used isotemporal substitution to investigate the effects of substituting activity categories in an equal time exchange fashion on health and fitness in young people. METHODS: Participants were drawn from schools in Camden, London (n = 353, mean age 9.3 ± 2.3 years). Time sedentary, in light and in moderate-to-vigorous activity (MVPA) was measured via accelerometry. The effects of substituting time in activity categories (sedentary, light and MVPA) with equivalent time in another category on health and fitness were examined using isotemporal substitution. RESULTS: In single and partition models, MVPA was favourably associated with body fat %, horizontal jump distance and flexibility. Time sedentary and in light activity were not associated with health and fitness outcomes in these models. In substitution models, replacing one hour of sedentary time with MVPA was favourably associated with body fat % (B = -4.187; 95% confidence interval (CI), -7.233, -1.142), horizontal jump distance (B = 16.093; 95% CI, 7.476, 24.710) and flexibility (B = 4.783; 95% CI, 1.910, 7.656). Replacing time in light activity with MVPA induced similar benefits but there were null effects for replacing sedentary with light intensity. CONCLUSION: Substituting time sedentary and in light activity with MVPA was associated with favourable health and fitness. Time in sedentary behaviour may only be detrimental to health and fitness when it replaces time in MVPA in young people

"From the moment i wake up i will use it?every day, very hour": A qualitative study on the patterns of adolescents' mobile touch screen device use from adolescent and parent perspectives

Background: The use of mobile touch screen devices, e.g. smartphones and tablet computers, has become increasingly prevalent among adolescents. However, little is known about how adolescents use these devices and potential influences on their use. Hence, this qualitative study explored adolescents' perceptions on their patterns of use and factors influencing use, and perceptions and concerns from parents. Methods: Semi-structured interviews were conducted with adolescents (n = 36; 11 to 18 years) and their parents/caregivers (n = 28) in Singapore recruited to represent males and females across a range of ages from different socioeconomic groups. Prompts covered weekday and weekend use patterns, types of activities, perspectives on amount of use, parental control measures and concerns. Interviews were recorded and transcribed. Transcripts were coded and thematic analysis was carried out. Results: Smartphone was the most common mobile device owned and used by many of the adolescents, while only some used a tablet. Many adolescents and their parents felt that adolescents' MTSD use was high, frequent and ubiquitous, with frequent checking of device and multitasking during use. Reported influences of use included functional, personal and external influences. Some of the influences were irresistibility of mobile devices, lack of self-control, entertainment or relaxation value, and high use by peers, family and for schoolwork that contributed to high use, or school/parental control measures and lack of internet availability that limited use. Most adolescents were generally unconcerned about their use and perceived their usage as appropriate, while most parents expressed several concerns about their adolescents' use and perceived their usage as excessive. Conclusions: This study has provided rich insights into the patterns and influences of contemporary mobile device use by adolescents. Mobile device use has become an integral part of adolescents' daily routines, and was affected by several functional, personal and external influences which either facilitated or limited their use. There also seemed to be a strong inclination for adolescents to frequently check and use their mobile devices. There is an urgent need to understand the implications of these common adolescent behaviours to inform advice for wise mobile device use by adolescents

A pilot study to investigate the safety of exercise training and testing in cardiac rehabilitation patients

We conducted a pilot study to evaluate the safety of the shuttle walking test (SWT) and exercise training for cardiac patients in community-based cardiac rehabilitation settings. Overall, 33 cardiac patients were tested (19 males and 14 females, 67 ± 8 years). Eleven cardiac patients (testing group) and 22 cardiac patients (training group) underwent ambulatory electrocardiogram (ECG) monitoring during the SWT and exercise training during a long-term cardiac rehabilitation programme. Frequency of ECG events was reported for the two groups. Chi-square test was performed to determine associations between the incidence of cardiovascular events and poor functional capacity (SWT <450 m). The findings showed only minor events provoked during the SWT or exercise training, and no event-related hospitalisation, syncope episodes or fatality. The most important cardiac event was silent, myocardial ischaemia (testing group: 27.3%; training group: 18%). Poor functional capacity was not associated with the risk of a cardiac event during exercise (testing group: X 2=0, p=0.99, phi=0.24; training group: X2=2.1, p=0.15, phi=-0.42). In conclusion, supervised exercise testing and training are accompanied only by minor cardiovascular events and they can be carried out safely in community-based cardiac rehabilitation settings

Temporal relationships between screen-time and physical activity with cardiorespiratory fitness in English Schoolchildren: A 2-year longitudinal study

Objective: To determine the temporal relationships screen-time and physical activity have with cardiorespiratory fitness. Method: Measures were made over two years (2008-2010) in 1500 participants aged 11.5 (SD 0.5) years at baseline. Results: Tracking coefficients were low-to-moderate for all measures. At follow-up, 25% of participants moved from having low (< 2. h) to high (≥ 2. h) daily screen-time and 6% became unfit according to FITNESSGRAM standards. Baseline screen-time was the strongest univariate predictor of becoming unfit. Multivariate analysis controlling for decimal age, BMI and deprivation confirmed baseline screen-time as the strongest independent predictor of becoming unfit over the 2-year study period (OR 2.4; 95%CI:1.4-4.0). Current (OR 2.3; 95%CI:1.3-4.0) and previous (OR 1.7; 95%CI:1.0-2.9) physical activity levels also independently predicted becoming unfit. Conclusion: There is currently no guidance for limiting screen-time in UK children. These longitudinal data add to the cross-sectional evidence of lower physical activity and fitness in children reporting ≥ 2. h daily screen-time. More importantly, these data demonstrate that high screen-time during childhood is an independent predictor of lower cardiorespiratory fitness in adolescence. © 2012 Elsevier Inc.

Randomized controlled trial of supervised exercise to evaluate changes in cardiac function in patients with peripheral atherosclerotic disease

SummaryIntroduction:  Peripheral atherosclerotic disease (PAD) is a condition characterized by low functional capacity which is associated with impaired free living, ambulation and low exercise tolerance. The purpose of this randomized controlled study was to evaluate whether changes in maximal walking time are associated with adaptations in cardiovascular function following supervised exercise.Methods:  After ethics approval, 28 patients (63 ± 11 years) completed a graded treadmill test (2 min stages, 3·2 km h−1, with gradient increasing 2% every 2 min) until they reached level three or four on the claudication pain scale. Peak oxygen consumption was assessed on a breath‐by‐breath basis, by online expiratory gas analysis. Following a 40‐min recovery period, peak cardiac output was measured using the non‐invasive carbon dioxide rebreathing method described by Defares (J Appl Physiol, 13, 1958, 159). Peak cardiac power output was then computed using the equation described by Cooke et al. (Heart, 1998, 79, 289). Patients were randomly assigned to one of two groups: supervised, who exercised at the hospital twice weekly for 12 weeks or control, who received normal treatment which included encouragement to walk regularly.Results:  After 12 weeks, there were no significant changes in body mass, peak oxygen consumption, peak cardiac output, peak heart rate, peak cardiac power output, respiratory exchange ratio or rating of perceived exertion in both the supervised and control group. There was a significant improvement (91%) in maximal walking distance following the supervised exercise programme. Although patients’ peak cardiovascular measurements were unchanged, the patients in the supervised exercise group were able to complete a higher workload at the end of the 12 weeks of exercise, for the equivalent demands on the circulation system.Conclusions:  The findings from this study suggest that a short‐term period of supervised exercise training results in an improved walking time in patients with limiting claudication because of PAD. It also demonstrated that the cardiovascular system becomes more efficient in meeting the demands of exercise. It is recommended that individuals with PAD should undertake exercise as a form of treatment.</jats:p

Muscle strength is associated with lower diastolic blood pressure in schoolchildren

Cardiorespiratory fitness (CRF) provides protection against the elevated blood pressure in overweight youth. Less is known regarding any similar protective effect of muscular fitness. We investigated how handgrip strength, an easy to implement measure of muscular strength, interacted with CRF and BMI to determine blood pressure in youth. We measured systolic (SBP) and diastolic (DBP) blood pressure, handgrip strength (HG), CRF and body mass index (BMI) in n = 7329 10–16 year-olds (47% girls). We defined elevated blood pressure as > 91st percentile and Good HG as > 33rd percentile. Participants were classified as Fit or Unfit and as Normal or Overweight/Obese based on international standards. The prevalence of elevated SBP was 23%, and 44% of participants had elevated DBP. In unfit participants Good HG was associated with lower SBP (z = 0.41 (95%CI: 0.20–0.61) and DBP (z = 0.29 (95%CI: 0.12–0.47). In Overweight/Obese participants, DBP was z = 0.24 (95%CI: 0.14–0.34) lower in the Good (versus Low) HG group. Overweight/Obese participants with Good HG also had a 32% lower risk of elevated DBP (OR: 0.68, 95%CI: 0.57–0.82). This association was attenuated but remained important after adjusting for BMI (20% risk reduction, OR: 0.80, 95%CI: 0.63–1.01). Muscular fitness appears to play some protective role against the risk of elevated blood pressure; particularly for the more prevalent measure: elevated DBP (44%). Effects may be restricted to Overweight and Unfit youth it is these the increased risk of elevated BP is and are less likely to engage in traditional cardiorespiratory fitness training. Research to determine the effects of muscular fitness training on blood pressure is warranted in these subgroups