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Background: This study aimed at evaluating the effect of the “Walk,” an 8-month physical activity (PA) program led by classroom and physical education teachers, on the motor competence (MC) and PA of 5- to 6-year-old children. Methods: A total of 143 children (mean age = 61.51 [1.85] mo) participated in the study and were randomly assigned to the experimental and control groups. Children's MC was assessed by the Körperkoordination Test für Kinder (KTK), and PA was objectively measured by Omron HJ-720IT-E2 pedometers. Measurements were performed at baseline, midintervention, and postintervention. A 1-sample t test computed at baseline step counts revealed that children presented significantly lower PA than recommended for their age (P < .001). To examine the effect of the intervention on children's MC and PA, several repeated-measures analyses of variance were utilized on (1) KTK item scores and (2) pedometer data. Results: The results revealed that the Walk project led to practically significant changes in the experimental group compared with the control group in both MC (P < .001, η 2 > .14 for all KTK items) and PA (P < .001, η 2 = .23). Conclusions: This study highlights the efficacy of a PA project, involving both classroom and physical education teachers, for the enhancement of children's MC and PA. © 2019 Human Kinetics, Inc.

Background: Pre-school years are important for adopting health behaviours; however, today’s children seem to be overweight, present low physical activity (PA) levels and exceed screen time (ST) recommendations. Aim: To examine (a) time trends in PA in Greek pre-school children, (b) the associations among PA, body mass index (BMI) and ST and (c) potential PA differences between boys and girls. Subjects and methods: Data from five cross-sectional cohorts (2005 [n = 252]; 2008 [n = 212]; 2011 [n = 187]; 2014 [n = 194]; 2017 [n = 128]) were compared. PA was assessed using Omron HJ-720IT-E2 pedometers, whereas ST was reported by participants’ parents. A 4-way ANOVA was applied on children’s average week step counts. Results: A significant association (F = 828.90, p < 0.001, η2 = 0.638) between ST and PA was revealed, with children that had ST < 1 hour/day presenting the higher PA levels and being the only ones that met PA recommendations (11,500 steps/day). Statistically significant PA differences, though of no practical importance, were found among cohorts. There were no significant PA differences between boys and girls or among BMI categories. Nevertheless, obesity prevalence was found to exist at alarming levels (24.5% in 2008–41.4% in 2017), and a large percentage of children (23.6% in 2008–63.3% in 2017) presented excessive ST (> 2 hours/day). Conclusion: Effective interventions aiming at reducing ST and enhancing PA seem imperative if children’s health is to be safeguarded. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.

The aim of this study was to assess the effect of the hand’s acceleration on the propulsive forces and the relative contribution of the drag and lift on their resultant force in the separate phases of the front crawl underwater arm stroke. Ten female swimmers swam one trial of all-out 25-m front crawl. The underwater motion of each swimmer’s right hand was recorded using four camcorders and four periscope systems. Anatomical landmarks were digitised, and the propulsive forces generated by the swimmer’s hand were estimated from the kinematic data in conjunction with hydrodynamic coefficients. When the hand’s acceleration was taken into account, the magnitude of the propulsive forces was greater, with the exception of the mean drag force during the final part of the underwater arm stroke. The mean drag force was greater than the mean lift force in the middle part, while the mean lift force was greater than the mean drag force in the final part of the underwater arm stroke. Thus, swimmers should accelerate their hands from the beginning of their backward motion, press the water with large pitch angles during the middle part and sweep with small pitch angles during the final part of their underwater arm stroke. © 2014, © 2014 Taylor & Francis.

Background: Pre-school age is important for developing healthy attitudes towards physical activity (PA). However, research on pre-schoolers' pedometer-determined PA is limited. Aim: To describe pre-schoolers' ambulatory activity; investigate step count differences in respect to Body Mass Index (BMI) categories and examine the prevalence of obesity. Subjects and methods: Pre-school aged children (n=250; 5.5±0.4 years) from Komotini (Greece) wore Omron HJ-720IT-E2 pedometers for 10 consecutive days. Height and weight were measured and BMI was calculated. Results: Three-way repeated measures ANOVAs revealed that children performed more steps on weekdays than during weekends (p

The aim of this study was to examine the influence of leg kick on the pattern, the orientation and the propulsive forces produced by the hand, the efficiency of the arm stroke, the trunk inclination, the inter-arm coordination and the intra-cyclic horizontal velocity variation of the hip in sprint front crawl swimming. Nine female swimmers swam two maximal trials of 25 m front crawl, with and without leg kick. Four camcorders were used to record the underwater movements. Using the legs, the mean swimming velocity increased significantly. On the contrary, the velocity and the orientation of the hand, the magnitude and the direction of the propulsive forces, as well as the Froude efficiency of the arm stroke were not modified. The hip intra-cyclic horizontal velocity variation was also not changed, while the index of coordination decreased significantly. A significant decrease (13%) was also observed in the inclination of the trunk. Thus, the positive effect of leg kick on the swimming speed, besides the obvious direct generation of propulsive forces from the legs, could probably be attributed to the reduction of the body's inclination, while the generation of the propulsive forces and the efficiency of the arm stroke seem not to be significantly affected. © 2013 Taylor & Francis.

The study examined the changes of training load and physiological parameters in relation to competitive performance during a period leading to a national championship. The training content of twelve swimmers (age: 14.2±1.3 yrs) was recorded four weeks before the national championship (two weeks of normal training and two weeks of the taper). The training load was calculated: i) by the swimmer's session-RPE score (RPE-Load), ii) by the training intensity levels adjusted after a 7x200-m progressively increasing intensity test (LA-Load). Swimmers completed a 400- m submaximal intensity test, a 15 s tethered swimming and hand-grip strength measurements 34-35 (baseline: Test 1), 20-21 (before taper: Test 2) and 6-7 (Test 3) days before the national championship. Performance during the national championship was not significantly changed compared to season best (0.1±1.6%; 95% confidence limits: -0.9, 1.1%; Effect Size: 0.02, p=0.72) and compared to performance before the start of the two-week taper period (0.9±1.7%; 95% confidence limits: 0.3, 2.1%; Effect size: 0.12, p=0.09). No significant changes were observed in all measured physiological and performance related variables between Test 1, Test 2, and Test 3. Changes in RPE-Load (week-4 vs. week-1) were correlated with changes in performance (r=0.63, p=0.03) and the RPE-Load was correlated with the LALoad (r=0.80, p=0.01). The estimation of the session-RPE training load may be helpful for taper planning of young swimmers. Increasing the difference between the normal and last week of taper training load may facilitate performance improvements. © Editorial Committee of Journal of Human Kinetics.

Physiological responses and strokeparameter changes during interval swimming in different age-group female swimmers. J Strength Cond Res 26(12): 3312-3319, 2012-The purpose of the study was to examine the physiological responses, the stroke-parameter changes, and the ability to sustain a velocity corresponding to critical velocity (CV) during interval swimming on female swimmers of different age groups. Eight children (C; age: 10.4 6 0.6 years), 11 young (Y; age: 13.1 6 0.4 years), and 7 adults (A; age: 19.9 6 4.6 years) swam all-out efforts of 50, 100, 200, 400 m for CV and critical stroke rate (CSR) calculation. Subsequently, the swimmers performed an interval training set of 5 3 300-m (C) and 5 3 400-m repetitions (Y and A) at a velocity corresponding to CV. The CV was higher in the Y and A compared with the C group (C: 0.962 6 0.05, Y: 1.168 ± 0.09, A: 1.217 6 0.05 m.s-1, p < 0.05). The velocity of 5 3 300 and 5 3 400 m was not different compared with CV (C: 100 6 2%, Y: 98 6 3%, A: 98 6 3% of CV, p > 0.05). The blood lactate concentration was similar between groups and was maintained steady within each group (C: 4.5 ± 1.4, Y: 4.9 Plusmn; 1.4, A: 3.9 ± 1.3 mmol.L-1, p > 0.05). Heart rate was higher in the C and Y compared with the A group during the last 100 m of each repetition (p < 0.05). Stroke rate remained unchanged during the repetitions and was similar between groups and no different to the CSR (p > 0.05). Stroke length of the fifth repetition was 4.5 6 4.0% shorter compared with the second repetition in the Y and 5.3 ± 2.0% shorter compared with the first repetition in the A group (p < 0.05). During the 28- to 31-minute duration intermittent swimming, children and young and adult female swimmers were able to sustain CV with a steady and similar blood lactate concentration. Decreased stroke length may indicate an earlier fatigue in young and adult swimmers. © 2012 National Strength and Conditioning Association.

Objectives: The purpose of this study was to examine the physiological responses on three interval training sets performed at intensities relative to the critical velocity which was calculated from two different combinations of distances using a 2-parameter linear model. Methods: In a controlled repeated measures design, ten male well trained swimmers (age: 15.2±1.2years) swam 5×400-m, 10×200-m and 20×100-m on separate days with rest to swimming ratio 1:8, aiming to maintain the critical velocity calculated from distances of 50, 100, 200, 400-m (CV4) or 200, 400-m (CV200-400). Results: The sustained velocity on the 5×400-m was lower compared to CV4 and velocity on the 20×100-m was higher compared to CV200-400. The velocity on the 10×200-m was kept similar to both CV4 and CV200-400 (5×400-m: 1.27±0.07 vs. CV4: 1.33±0.09ms-1, p0.05). The blood lactate concentration increased after 1200 compared to 400-m (4.45±0.23 vs. 5.82±0.24mmoll-1, p0.05). Stroke rate and stroke length were not different between and within conditions (p>0.05). Heart rate during the recovery periods was lower in the 5×400-m compared to 10×200-m and 20×100-m training set (p

The objectives of the present investigation were to study the inflammatory and performance responses after an acute bout of intense plyometric exercise during a prolonged recovery period. Participants were randomly assigned to either an experimental group (P, n = 12) that performed intense plyometric exercises or a control group (C, n = 12) that rested. The delayed onset of muscle soreness (DOMS), knee range of motion (KROM), creatine kinase (CK) and lactate dehydrogenase (LDH) activities, white blood cell count, C reactive protein (CRP), uric acid (UA), cortisol, testosterone, IL-6, IL-1b strength (isometric and isokinetic), and countermovement (CMJ) and static (SJ) jumping performance were measured at rest, immediately postexercise and at 24, 48, 72, 96, and 120 hours of recovery. Lactate was measured at rest and postexercise. Strength remained unchanged throughout recovery, but CMJ and SJ declined (p < 0.05) by 8-20%. P induced a marked rise in DOMS, CK, and LDH (peaked 24-48 hours postexercise) and a KROM decline. An acute-phase inflammatory response consisting of leukocytosis (postexercise and at 24 hours), an IL-6, IL-1b, CRP, and cortisol elevation (during the first 24 hours of recovery) and a delayed increase of UA (peaked at 48 hours) and testosterone (peaked at 72 hours) was observed in P. The results of this investigation indicate that performing an acute bout of intense plyometric exercise may induce a short-term muscle damage and marked but transient inflammatory responses. Jumping performance seems to deteriorate for as long as 72 hours postexercise, whereas strength appears to remain unchanged. The acute-phase inflammatory response after a plyometric exercise protocol appears to follow the same pattern as in other exercise models. These results clearly indicate the need of sufficient recovery between successive plyometric exercise training sessions. © 2010 National Strength and Conditioning Association.

The main purpose of this study was the identification of the current pedometer determined physical activity levels of a large sample of 9 -14 years old Greek schoolchildren and the determination of the association between daily step counts and body mass index through the comparison of step counts among overweight, obese and normal-weight children. A total of 532 children (263 boys and 269 girls) were measured for height and weight. Their activity levels were analyzed using pedometers to measure mean steps for 7 consecutive days. Overweight and obese status was determined using the international reference standard (Cole et al., 2000). According to data analysis mean step counts ranged from 15371 to10539 for boys and from 11536 to 7893 for girls. Steps per day were significantly more for boys compared to girls. Children with normal weight performed significantly more steps per day compared to their overweight and obese classmates. Daily step counts reported in this study for 9 -14 year old schoolchildren were relatively low when compared to step counts from other European countries. Only 33.9% of the participants satisfied the body mass index referenced standards for recommended steps per day. Finally, the results of this study provide baseline information on youth pedometer determined physical activity and on youth body mass index levels. High prevalence of low daily step counts and BMI determined obesity was revealed prompting for further exploration of the relationship between objectively measured physical activity and adiposity in particular for children and adolescents that experience both health risk factors. Key pointsThe mean steps/day taken by both boys and girls in Greece 9-14 years old were 13.446 and 10.656 respectively.Daily step counts tended to be leveled for ages 9-12 years and a significant drop in steps/day was apparent for children aged 13 -14 years.According to the IOTF criteria, 23% of the boys that participated in this study were overweight and 7.8% were obese, while in girls the respective rates were 24.8% and 4.7%.Children with normal weight performed significantly more steps/day than the overweight and the obese children.