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1.
This randomised controlled trial investigated changes in eccentric hamstring strength, 10m sprint speed, and change-of-direction (COD) performance immediately post Nordic hamstring curl (NHC) intervention and following a 3-week detraining period.

Fourteen male team sports athletes were randomised to a do-as-usual control group (CG; = 7) or to a NHC intervention group (NHC; = 7). Isokinetic dynamometry at 180°/s evaluated eccentric hamstring strength immediately post-intervention as the primary outcome measure. Secondary outcomes included 10 m sprint time and COD. Each outcome was measured, pre, immediately post-intervention and following a 3-week detraining period.

Immediately post-intervention significant group differences were observed in the NHC group for eccentric hamstring strength (31.81 Nm?1 vs. 6.44 Nm?1, P = 0.001), COD (?0.12 s vs. 0.20 s; P = 0.003) and sprint (- 0.06 s vs. 0.05 s; P = 0.024) performance. Performance improvements were maintained following a detraining period for COD (?0.11 s vs. 0.20 s; P = 0.014) and sprint (?0.05 s vs. 0.03 s, P = 0.031) but not eccentric hamstring strength (15.67 Nm?1 vs. 6.44 Nm?1, P = 0.145) These findings have important implications for training programmes designed to reduce hamstring injury incidence, whilst enhancing physical qualities critical to sport.  相似文献   


2.
Purpose: To determine the accuracy of critical power (CP) and W? (the curvature constant of the power-duration relationship) derived from self-paced time-trial (TT) prediction trials using mobile power meters to predict 16.1-km road cycling TT performance. This study also aimed to assess the agreement between functional threshold power (FTP) and CP.

Methods: Twelve competitive male cyclists completed an incremental test to exhaustion, a FTP test and 4–5 self-paced TT bouts on a stationary bike within the lab, and a 16.1 km road TT, using mobile power meters.

Results: CP and W? derived from the power-duration relationship closely predicted TT performance. The 16.1-km road TT completion time (26.7 ± 2.2 min) was not significantly different from and was significantly correlated with the predicted time-to-completion (27.5 ± 3.3 min, = 0.89, < 0.01). CP and FTP were not significantly different (275 ± 40 W vs. 278 ± 42 W, > 0.05); however, the limits of agreement between CP and FTP were 30 to -36 W.

Discussion: The findings of this study indicate that CP and W? determined using mobile power meters during maximal, self-paced TT prediction trials can be used to accurately predict 16.1-km cycling performance, supporting the application of the CP and W? for performance prediction. However, the limits of agreement were too large to consider FTP and CP interchangeable.  相似文献   


3.
Bubble formation during scuba diving might induce decompression sickness.

This prospective randomised and double-blind study included 108 advanced recreational divers (38 females). Fifty-four pairs of divers, 1 breathing air and the other breathing nitrox28 undertook a standardised dive (24 ± 1 msw; 62 ± 5min) in the Red Sea. Venous gas bubbles were counted (Doppler) 30–<45 min (early) and 45–60 min (late) post-dive at jugular, subclavian and femoral sites.

Only 7% (air) vs. 11% (air28®) (n.s.) were bubble-free after a dive. Independent of sampling time and breathing gas, there were more bubbles in the jugular than in the femoral vein. More bubbles were counted in the air-group than in the air28-group (pooled vein: early: 1845 vs. 948; P = 0.047, late: 1817 vs. 953; P = 0.088). The number of bubbles was sex-dependent. Lastly, 29% of female air divers but only 14% of male divers were bubble-free (P = 0.058).

Air28® helps to reduce venous gas emboli in recreational divers. The bubble number depended on the breathing gas, sampling site and sex. Thus, both exact reporting the dive and in particular standardising sampling characteristics seem mandatory to compare results from different studies to further investigate the hitherto incoherent relation between inert gas bubbles and DCS.  相似文献   


4.
This study characterises the relationship between gait variability and speed in runners using data from trunk accelerations in each axis.

Twelve participants of varying fitness ran on the treadmill with three sessions of six randomly ordered self-selected speeds. A VO2max test was conducted on the fourth session. Running gait was tracked with inertial sensors. The occurrence of a mid-range speed was analysed for the anterior–posterior, vertical and lateral directional coefficient of variation (CV) of root mean square (RMS) acceleration data.

One participant with noisy gait signals was omitted. The results show all remaining participants consistently showed significant quadratic U-shaped relationships between vertical RMS CV acceleration and speed. Neither anterior–posterior nor lateral RMS CV acceleration were clearly related to speed. These least variable gait speeds were similar to estimates of optimal speed derived from minimum cost of transport with speed.

In conclusion, there exists a mid-range speed for each runner with the least variable gait in the vertical direction, and this occurred significantly more often than would be expected by chance (P < 0.05). However, there are no prominent patterns for the anterior–posterior and lateral directions. This finding supports anecdotal evidence from runners and coaches concerning gait consistency.  相似文献   


5.
Although a low rolling resistance is advantageous in mountain bike cross-country racing, no studies have used the virtual elevation method to compare tyres from different manufacturers as used in international competitions so far. The aims of this study were to assess the reliability of this method, to compare the off-road rolling resistance between tyres and to calculate the influence on off-road speed.

Nine 29-in. mountain bike cross-country tyres were tested on a course representing typical ground surface conditions 5 or 6 times. The coefficient of rolling resistance was estimated with the virtual elevation method by 3 investigators and corresponding off-road speeds were calculated.

The virtual elevation method was highly reliable (typical error = 0.0006, 2.8%; limits of agreement <0.0005, r ≥ 0.98). The mean coefficient of rolling resistance was 0.0219 and differed from 0.0205 to 0.0237 (P < 0.001) between tyres. The calculated differences in off-road speed amounted to 2.9–3.2% (0% slope) and 2.3–2.4% (10% slope) between the slowest and the fastest tyre.

The reliability of the method and the differences in rolling resistance between the tyres illustrate the value of testing tyres for important competitions on a representative ground surface using the virtual elevation method.  相似文献   


6.
Previous studies suggest that increasing the skill level of judokas will decrease the number of head injuries sustained during judo. However, the kinematics are poorly understood, making it difficult to establish an effective breakfall teaching programme. Therefore, we studied the kinematic parameters of breakfall for osoto-gari to identify the risk of judo-related head injuries by comparing experienced and novice judokas. This information will provide insight into developing a better prevention plan for judo-related head injuries.

A total of 10 experienced and 12 novice judokas volunteered to participate in this study. The kinematic data of the breakfall motion for osoto-gari were collected using a three-dimensional motion analysis technique (200 Hz).

We observed a significantly higher peak neck extension momentum in the novice group than in the experienced group. This suggests that neck extension momentum during breakfall is associated with the risk of head injuries during judo. In addition, the novice judokas demonstrated a significantly greater flexed pattern in the trunk and hip movement than the experienced judokas (P < 0.05). The results suggest that the trunk and lower extremity motion are important kinematic parameters that determine the skill level in performing the breakfall for osoto-gari.  相似文献   


7.
Objective: To analyze the possible dose-response association between components of sports participation (intensity, volume and previous engagement) and 4-year mortality rates among Brazilian adults.

Methods: 679 males and females (mean age among men = 66.7 ± 9.3 years old and mean age among women = 64.8 ± 8.9 years old) composed the study sample. Sports participation was assessed using Baecke’s questionnaire, which considers intensity, duration and previous engagement. Medical records were used to identify the cause of the death. Cox regression analysis was performed to determine the independent associations of exercise components and mortality.

Results: Participants that reported exercising at moderate-vigorous intensity (Moderate/vigorous: 4.1% versus None/light: 10.3% [p-value = 0.012]; HR = 0.42 [0.1 to 0.94)] and for more than four months (≥4 months: 5.3% versus <4 months: 10.2% [p-value = 0.038]; HR = 0.47 [0.24 to 0.94]) had lower mortality risk. The percentage of survival according to all-cause mortality was significantly higher for participants engaged in sports at moderate-vigorous intensity (p-value = 0.014), as well as for those engaged in sports for periods superior than four months (p-value = 0.036).

Conclusion: We found higher percentage of survival among adults engaged in sports at moderate-vigorous intensity and with at least four months of previous engagement.  相似文献   


8.
Despite proprietary algorithms to account for differences, output from activity trackers worn on different wrists may not be comparable because individuals vary in their reliance on each hand during free-living activities.

Participants (n = 48) wore Fitbit Flex or Flex2 monitors on each wrist for three days. T tests, equivalence tests, and correlations were used to compare steps, Calories, distance, active minutes, and sleep duration recorded by dominant and nondominant wrist-worn monitors and effect sizes and mean absolute and percent difference were calculated.

The nondominant Flex2 monitor was not equivalent to the dominant wrist-worn monitor and recorded significantly more steps/day (absolute difference = 708), miles/day (0.3), and active minutes/day (7.9) than the dominant Flex2 monitor. For all variables, nondominant and dominant output was correlated (r>0.75).

Nondominant and dominant Flex2 monitors are significantly different, but there were small differences for Flex monitors. Research should investigate effects on behavior and replicate findings using other monitors.  相似文献   


9.
This study targeted to examine the effect of the ToyBox-intervention, a kindergarten-based, family-involved intervention, aiming to improve preschooler’s energy-related behaviours (e.g., physical activity) on motor performance ability. Physical activity sessions, classroom activities, environmental changes and tools for parents were the components of the 1-year intervention. The intervention and control were cluster-randomised, and children’s anthropometry and two motor test items (jumping from side to side, JSS and standing long jump, SLJ) were assessed. A total of 1293 (4.6 ± 0.69 years; 52% boys) from 45 kindergartens in Germany were included (intervention, n = 863; control, n = 430). The effect was assessed using generalised estimating equation. The intervention group showed a better improvement in JSS (Estimate 2.19 jumps, P = 0.01) and tended to improve better in SLJ (Estimate 2.73 cm, P = 0.08). The intervention was more effective in boys with respect to SLJ (P of interaction effect = 0.01). Children aged <4.5 years did not show a significant benefit while older children improved (JSS, Estimate 3.38 jumps, P = 0.004; SLJ, Estimate 4.18 cm, P = 0.04). Children with low socio-economic status improved in JSS (Estimate 5.98 jumps, P = 0.0001). The ToyBox-intervention offers an effective strategy to improve specific components of motor performance ability in early childhood. Future programmes should consider additional strategies specifically targeting girls and younger aged children.

Abbreviations: BMI: body mass index; SES: socio-economic status; JSS: jumping from side to side; SLJ: standing long jump; SD: standard deviation; GEE: generalised estimating equation  相似文献   


10.
Tools for measuring walking time make use of objective and subjective methods. One subjective approach is to administer physical activity questionnaires (PAQ), mainly because they are inexpensive and easy to give to large groups. The European Prospective Investigation into Cancer and Nutrition (EPIC) study has a brief PAQ (EPIC-PAQ) and includes one question referencing walking time. The objective of this study was to assess the validity of the question about time spent walking included in the EPIC-PAQ.

The sample included 200 older adults (113 women). To assess daily walking time, participants responded to the EPIC-PAQ in an interview and wore a portable gait analysis system and physical activity monitor for 48 consecutive hours in free-living condition.

Results indicated that the mean of bias between the EPIC-PAQ and objetive measurement was ?64.6 min/day. Also, the correlation was low compared to an objective measurement (rho = 0.196) and was positively correlated with the time spent at speeds below 2.5 mph but the correlation was low (slow walking rho = 0.154 and pace walking rho = 0.163).

The EPIC-PAQ shows low correlations with the objective measurement of walking time, that suggests it may be inaccurate and affecting the estimate of the EPIC-PAQ’s PA energy expenditure in this age group.  相似文献   


11.
The purpose of this study was to examine the feasibility and validity of an Athletic Skills Track (AST) to assess fundamental movement skills among 6- to 12-year-old children in a physical education setting. Four hundred sixty-three Dutch children (211 girls, 252 boys) completed three tests: the Körperkoordinationstest für Kinder (KTK) and two Athletic Skills Tracks (AST-1, AST-2). The validity of AST-1 and AST-2 was examined by correlating the time (s) needed to complete the tracks and the KTK Motor Quotient (MQ).

Overall, there was a low correlation between AST-1 and the KTK MQ (r = –0.474 (P < 0.01)) and a moderate correlation between AST-2 and the KTK MQ (r = –0.502 (< 0.01)). When split up by age group the associations were much higher and ranged between r = –0.469 and r = –0.767), with the exception of the low correlation coefficient of the AST-2 in 7-year-olds. The results indicate that fundamental movement skills of 6- to 12-year-old children can be assessed with a quick, convenient and low-cost motor competence test in a physical education setting, i.e., an Athletic Skills Track. Future studies should further assess the reliability, discriminative ability and validity of age-specific versions of the AST.  相似文献   


12.
The warm-up programme “FIFA 11+” has been shown to reduce football injuries in different populations, but so far veteran players have not been investigated. Due to differences in age, skill level and gender, a simple transfer of these results to veteran football is not recommended. The purpose of this study was to investigate the preventive effects of the “FIFA 11+” in veteran football players.

Twenty veteran football teams were recruited for a prospective 9-month (1 season) cluster-randomised trial. The intervention group (INT, n = 146; 45 ± 8 years) performed the “FIFA 11+” at the beginning of each training session, while the control group (CON, n = 119; 43 ± 6 years) followed its regular training routine. Player exposure hours and injuries were recorded according to an international consensus statement.

No significant difference was found between INT and CON in overall injury incidence (incidence rate ratio [IRR]: 0.91 [0.64–1.48]; P = 0.89). Only severe injuries reached statistical significance with higher incidence in CON (IRR: 0.46 [0.21–0.97], P = 0.04).

Regular conduction (i.e. once a week) of the “FIFA 11+” did not prevent injuries in veteran footballers under real training and competition circumstances. The lack of preventive effects is likely due to the too low overall frequency of training sessions.  相似文献   


13.
Background: Teaching for social good and inequity has been presented as needed in sport pedagogy research. However, very little is known how transformative pedagogical practices that teach for social good are implemented and sustained at the elementary level.

Purpose: This digital ethnographic study sought to describe one elementary school physical education (PE) teacher's attempt to employ transformative pedagogy (TP).

Method: Cochran-Smith's [1998. “Teaching for Social Change: Toward a Grounded Theory of Teacher Education.” In The International Handbook of Educational Change, edited by A. Hargreaves, A. Lieberman, M. Fullan, and D. Hopkins, 916–952. Netherlands: Kluwer Academic Publishers, 2004. Walking the Road: Race, Diversity, and Social Justice in Teacher Education. New York: Teachers College Press] pedagogical principles for social justice education (SJE) drove our data collection and analysis. Seven qualitative methods were employed to collect data about Harry's pedagogies, organizational structures, and the content he taught. These were formal and informal interviews, conversations, short films, document collection, social media accounts, and an electronic journal. Data were analyzed using both inductive and deductive methods [Patton 2015. Qualitative Research and Evaluation Methods. 4th ed. Thousand Oaks: Sage].

Findings: Harry's TP and the factors that facilitated and limited his practice were uncovered within five main themes: (a) creating communities of learners through restorative practice principles, (b) building on what students bring to school with them for a democratic curriculum, (c) teaching skills, bridging gaps, and the affective component, (d), working with communities in-between social justice illiteracy, and (e) utilizing diverse forms of assessment.

Conclusion: We confirmed that there is no best way to teach social justice through PE and that TP must be individual to the teacher. In addition, this study highlighted methods and pedagogies by which teachers could engage in TP. Finally, the study's findings implied how teacher educators might go about working with both preservice and inservice PE teachers with the goal that they focus on facilitating social justice through their pedagogical approach.  相似文献   


14.
This study compared the effects of 12-week sprint interval training (SIT), high-intensity interval training (HIIT), and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (V?O2peak), body mass and insulin sensitivity in overweight females. Forty-two overweight women (age 21.2 ± 1.4 years, BMI 26.3 ± 2.5 kg·m?2) were randomized to the groups of SIT (80 × 6-s sprints + 9-s rest), and isoenergetic (300KJ) HIIT (~9 × 4-min cycling at 90% V?O2peak + 3-min rest) and MICT (cycling at 60% V?O2peak for ~ 61-min). Training intervention was performed 3 d·week?1 for 12 weeks. After intervention, all three groups induced the same improvement in V?O2peak (~ +25%, p < 0.001) and a similar reduction in body mass (~ – 5%, p < 0.001). Insulin sensitivity and fasting insulin levels were improved significantly on post-training measures in SIT and HIIT by ~26% and ~39% (p < 0.01), respectively, but remain unchanged in MICT. In contrast, fasting glucose levels were only reduced with MICT (p < 0.01). The three training strategies are equally effective in improving V?O2peak and reducing body mass, however, the SIT is time-efficient. High-intensity training (i.e. SIT and HIIT) seems to be more beneficial than MICT in improving insulin sensitivity.

Abbreviations: BMI: body mass index; CVD: cardiovascular disease; HIEG: hyperinsulinaemic euglycaemic glucose; HIIT: high-intensity interval training; HOMA-IR: homeostasis model assessment of insulin resistance; HR: heart rate; MICT: moderate-intensity continuous training; RPE: ratings of perceived exertion; SIT: sprint interval training; T2D: type 2 diabetes; V?O2peak: peak oxygen consumption  相似文献   


15.
The purpose of this study was to test emotional responses during sprint intervals performed on a level, down and up surface. Fifty trained participants performed a maximal effort during a 60-m sprint and 10 repetitions of 60 m running sprints on a level, down and up surface on a 5.9% slope. Running speeds, emotional responses and heart rate were measured. Self-selected speeds were correlated with the rating of perceived exertion, the affective balance, the desire to stop and the resources needed for the task in all conditions whereas the pleasure, the desire to continue and the capacity to realise the task were correlated with speeds only during level and uphill running. Mean values of emotional parameters were significantly different (P < 0.05) during running on a flat surface, downhill and uphill. When the gradient of running surface is changed, the pattern of emotional responses was just translated, i.e. most of the slope between the evolution of emotional parameters and the repetitions were not significantly different whereas Y-intercepts were different.

Consented effort is highly correlated with the resources needed for the task (P < 0.001, r2 = 0.72). We propose that the difference in the resources needed for the task between level, downhill and uphill running (F 2, 1499 = 166.5, P < 0.001, Eta2 = 0.18) is the most important key that explains our results.  相似文献   


16.
Physical profile data from elite, sub-elite, regional, under 21s (U21), under 19s (U19) and under 17s (U17) (n = 845) players from a state netball association in Australia were analysed. Within season changes were examined for the elite and sub-elite players. Longitudinal changes were examined for the elite across four consecutive netball seasons.

Elite were significantly older (24.3 ± 3.4years), taller (182.4 ± 7.2cm) and heavier (73.42 ± 6.95kg) than other playing levels (p < 0.001, ES 0.49–3.26) and had higher vertical jump (VJ) data compared to all groups (p < 0.001, ES 0.47–0.93). U17’s were significantly faster than elite, sub-elite and U19 players over 5m (p < 0.05, ES 0.36–0.58) while elite were faster over 20m compared to all groups (p < 0.01, ES 0.45–0.72). Elite achieved a greater distance (1350.8m; p < 0.05, ES 0.32–0.50) in the Yo-YoIRT1 compared to the sub-elite, regional, U19 and U17. VJ height significantly increased from the 2014 (51.6 ± 4.8cm) to the 2017 season (59.6 ± 6.3cm) for the elite players (p < 0.01, ES 1.18). Yo-YoIRT1 test scores increased significantly between the pre-season and in-season phases (p < 0.05, ES 0.17).  相似文献   


17.
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.  相似文献   


18.
Purpose: To compare characteristics of club level male soccer players 11 and 13 years of age, and to evaluate playing status in soccer two and 10 years after baseline by birth quarter (BQ).

Methods: Youth players 11 (n = 62, born 1992, observed December 2003) and 13 (n = 50, born 1990, observed April 2004) years were grouped by BQ. Baseline data included stature, weight, maturity status, functional capacities, soccer skills, goal orientation, and coach evaluation of potential. Playing status in soccer in 2006 and 2014 was also available. Baseline characteristics and subsequent playing status were compared by BQ.

Results: Baseline characteristics did not differ by BQ except for age and percentage of predicted adult height. Though not significant, coaches tended to rate players in BQ1as higher in potential. For those competing in soccer as adults, BQ2 (4), BQ3 (5) and BQ4 (2) were represented among players11 years, and BQ1 (3), BQ2 (2), BQ3 (1) and BQ4 (4) among players 13 years.

Conclusion: Although limited to small numbers, differences among players by BQ were inconsistent. The results indicate a need to extend potential explanations of the RAE to include behavioral variables, coaches, training environment, and perhaps the culture of the sport.  相似文献   


19.
The aims of the present study were: i) to examine the associations of total accelerometer-based sedentary time (ST) and specific-domain self-reported ST (i.e., screen-based, educational-based, social-based, and other-based ST) with adiposity and physical fitness in youth; and ii) to analyse the mediation effect of physical activity (PA) on associations.

This study was conducted with 415 children (9.1 ± 0.4 years) and 853 adolescents (13.6 ± 1.6 years) in Spain during 2011–2012. Total ST and PA were assessed by accelerometry. Leisure-time spent in twelve sedentary behaviours was self-reported. Adiposity and physical fitness was measured following the ALPHA battery for youth.

Total accelerometer-based ST was positively associated with global adiposity score in children, and negatively associated with global physical fitness score in children and adolescents; but relationships were not independent of PA. PA mediated all associations of accelerometer-based and self-reported ST with adiposity or physical fitness in children. Conversely, screen-, educational-, social-, and other-based ST were negatively related to physical fitness in adolescents, independently of PA.

These findings give an impetus to developing effective strategies for specifically promoting PA in children and for increasing PA while reducing ST in adolescents in order to produce improvements on adiposity and physical fitness.  相似文献   


20.
The purpose of this study was to investigate the effects of interval aerobic training combined with strength exercise in the same training session on body composition, and glycaemic and lipid profile in obese rats. Sixteen lean Zucker rats and sixteen obese Zucker rats were randomly divided into exercise and sedentary subgroups (4 groups, n = 8). Exercise consisted of interval aerobic training combined with strength exercise in the same training session. The animals trained 60 min/day, 5 days/week for 8 weeks. Body composition, lipid and glycaemic profiles and inflammatory markers were assessed.

Results showed that fat mass was reduced in both lean and obese rats following the exercise training (effect size (95% confidence interval (CI)) = 1.8 (0.5–3.0)). Plasma low-density lipoprotein–cholesterol and fasting glucose were lower in the exercise compared to the sedentary groups (= 2.0 (0.7–3.2) and 1.8 (0.5–3.0), respectively). Plasma insulin was reduced in exercise compared to sedentary groups (= 2.1 (0.8–3.4)). Some exercise × phenotype interactions showed that the highest decreases in insulin, homeostatic model assessment-insulin resistance, fasting and postprandial glucose were observed in the obese + exercise group (all, P < 0.01). The findings of this study suggest that interval aerobic training combined with strength exercise would improve body composition, and lipid and glycaemic profiles, especially in obese rats.  相似文献   


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