Abstract: Targeting the weekend to promote physical activity (PA) in children seems to be promising given that they tend to be less physically active and, particularly, as the age-related decline in PA is more marked during weekends. Considering the ambiguity of why children are not able to maintain their PA level on weekends, the aim of the present study was to objectively investigate differences in children’s spatial PA patterns between week and weekend days using the combination of Global Positioning System (GPS) and accelerometry. Seventy-four second graders (aged 7–9 years) and 98 sixth graders (aged 11–14 years) wore an accelerometer and GPS sensor for seven consecutive days to determine where children spend time and engage in PA. Time-matched accelerometer and GPS data was mapped with a geographic information system and multilevel analyses accounting for the hierarchical structure of the data were conducted. Differences between weekdays and weekends regarding the total time spent and the absolute and relative level of PA in various settings were found in both age groups. The findings support previous research pointing to the importance of targeting weekend PA, especially when children grow older. Future interventions should encourage children to use outdoor spaces more frequently on weekends, rather than stay at home, and to commute actively to destinations other than school.
Abstract: Grinding is a key physical element in America’s Cup sailing. This study aimed to describe kinematics and muscle activation patterns in relation to torque applied in forward and backward grinding. Ten male America’s Cup sailors (33.6 ± 5.7 years, 97.9 ± 13.4 kg, 186.6 ± 7.4 cm) completed forward and backward grinding on a customised grinding ergometer. In forward grinding peak torque (77 Nm) occurred at 95° (0° = crank vertically up) on the downward section of the rotation at the end of shoulder flexion and elbow extension. Backward grinding torque peaked at 35° (69 Nm) following the pull action (shoulder extension, elbow flexion) across the top of the rotation. During forward grinding, relatively high levels of torque (>50 Nm) were maintained through the majority (72%) of the cycle, compared to 47% for backward grinding, with sections of low torque corresponding with low numbers of active muscles. Variation in torque was negatively associated with forward grinding performance (r = −0.60; 90% CI −0.88 to −0.02), but positively associated with backward performance (r = 0.48; CI = −0.15 to 0.83). Magnitude and distribution of torque generation differed according to grinding direction and presents an argument for divergent training methods to improve forward and backward grinding performance.
Abstract: The main objective was to analyze a friendly match of youth elite soccer players identifying the variance of tactical and physiological response parameters during the game. In addition, detecting the impact of both halves on player performance. For the purposes of this study twenty-two U19 players were analyzed playing 11v11. Activity profile, heart rate (HR and HRmax), grouped in five different zones were analyzed via Bluetooth technology, technical performance was analyzed by the Team Sport Assessment Procedure (TSAP), and tactical performance was measured by Social Network Analysis. A comparison of heart rate responses showed significant main effects in the halves (p = 0.001; = 0.623). A comparison between tactical position and technical performance had significant main effects (p = 0.001; = 0.390). Tactical position showed statistically significant effects on tactical prominence (p = 0.002; = 0.296). Therefore, fatigue is a component distinguished in technical/tactical parameters, such as volume of play and efficiency index. Results suggest that fatigue effects may constrain technical performance and, for that reason, the use of instruments to monitor the fatigue effect during matches may be suggested.
Abstract: Freshmen college soccer players will have lower training ages than their experienced teammates (sophomores, juniors, seniors). How this is reflected in field test performance is not known. Freshmen (n = 7) and experienced (n = 10) male field soccer players from the same Division I school completed soccer-specific tests to identify potential differences in incoming freshmen. Testing included: vertical jump (VJ), standing broad jump, and triple hop (TH); 30-m sprint, (0–5, 5–10, 0–10, and 0–30 m intervals); 505 change-of-direction test; Yo-Yo Intermittent Recovery Test Level 2 (YYIRT2); and 6 × 30-m sprints to measure repeated-sprint ability. A MANOVA with Bonferroni post hoc was conducted on the performance test data, and effect sizes and z-scores were calculated from the results for magnitude-based inference. There were no significant between-group differences in the performance tests. There were moderate effects for the differences in VJ height, left-leg TH, 0–5, 0–10 and 0–30 m sprint intervals, and YYIRT2 (d = 0.63–1.18), with experienced players being superior. According to z-score data, freshmen had meaningful differences below the squad mean in the 30-m sprint, YYIRT2, and jump tests. Freshmen soccer players may need to develop linear speed, high-intensity running, and jump performance upon entering a collegiate program.
Abstract: The purpose of the present study was to determine the prevalence of dietary supplements (DS’s) and sport nutrition product (SNPs) among the general population, to identify differences for gender, age, and exercise frequency, and to determine the main reasons for use. The study was designed as a web-based questionnaire in a representative sample (n = 1544) of the Dutch population. Sixty-two percent (n = 957) of the respondents reported having used DS’s, SNPs, or both in the last twelve months. Women and older people reported the highest DS use. The highest use of SNPs was reported by regular exercising men and younger people with improving sporting performance as their main objective. Most frequently reported DS’s were multivitamins (28%) and vitamin C (19%)—for SNPs, energy drinks (22%) and isotonic drinks (19%). Health considerations were the most important motivation (DS’s 90% and SNPs 52%), but also performance was substantially reported (DS’s 14% and SNPs 35%). A substantial group of sedentary respondents also reported the use of SNPs. This study confirms that DS’s, SNPs, or both are widely used among the general population. Both health as performance are important reasons for use. It can be questioned whether the use of SNPs fits all respondents’ physical activity needs.
Abstract: Cardiac natriuretic peptides (NPs) play an important role in the regulation of energy expenditure in skeletal muscle and adipose tissue. A systematic review on the effects of exercise on NPs in patients with heart failure reported that aerobic and resistance training reduced NPs; however, the effects of exercise on NPs and the underlying mechanism of exercise-induced NP secretion in subjects without heart failure remain unknown. In athletes and young, healthy subjects, the NP concentration at rest is not elevated, but strenuous endurance exercise significantly increases NPs. The exercise-induced increase in NPs may be caused by transient myocardial wall stress, cardiomyocyte metabolic changes, or neuroendocrinological response, which may have cytoprotective and growth-regulating effects on the heart. On the other hand, in elderly, overweight/obese subjects, and patients with hypertension, NP concentrations also increase during exercise; however, NP secretion may be more susceptible to cardiac stress compared to young, healthy individuals. Recent studies have shown that NPs are associated with thermogenesis in fat tissue and oxidative capacity in skeletal muscles. NPs may also have a protective role for skeletal muscle in humans, although further studies are warranted to elucidate the physiological mechanism of exercise-induced NP secretion.