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Helen J. Moore, Catherine A. Nixon, Amelia A. Lake, Wayne Douthwaite, Claire L. O’Malley, Claire L. Pedley, Carolyn D. Summerbell and Ashley C. Routen

Background:

Evidence suggests that many contemporary urban environments do not support healthy lifestyle choices and are implicated in the obesity pandemic. Middlesbrough, in the northeast of England is one such environment and a prime target for investigation.

Methods:

To measure physical activity (PA) levels in a sample of 28 adolescents (aged 11 to 14 years) and describe the environmental context of their activity and explore where they are most and least active over a 7-day period, accelerometry and Global Positioning System (GPS) technology were used. Twenty-five of these participants also took part in focus groups about their experiences and perceptions of PA engagement.

Results:

Findings indicated that all participants were relatively inactive throughout the observed period although bouts of moderate-vigorous physical activity (MVPA) were identified in 4 contexts: school, home, street, and rural/urban green spaces, with MVPA levels highest in the school setting. Providing access to local facilities and services (such as leisure centers) is not in itself sufficient to engage adolescents in MVPA.

Conclusion:

Factors influencing engagement in MVPA were identified within and across contexts, including ‘time’ as both a facilitator and barrier, perceptions of ‘gendered’ PA, and the social influences of peer groups and family members.

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Luke W. Hogarth, Brendan J. Burkett and Mark R. McKean

Purpose:

To examine the neuromuscular and perceptual fatigue responses to consecutive tag football matches played on the same day and determine the relationship between fatigue and match running performance.

Methods:

Neuromuscular and perceptual fatigue responses of 15 national tag football players were assessed before and during the 2014 State of Origin tournament. Global positioning systems (GPS) provided data on players’ match running performance, and a vertical-jump test and subjective questionnaire were used to assess players’ neuromuscular and perceptual fatigue, respectively.

Results:

There were small to moderate reductions in the majority of match-running-performance variables over consecutive matches, including distance (ES = −0.81), high-speed-running (HSR) distance (ES = −0.51), HSR efforts (ES = −0.64), and maximal accelerations (ES = −0.76). Prematch vertical jump was initially below baseline values before the first match (ES = 0.68−0.88). There were no substantial reductions in vertical-jump performance from baseline values over consecutive matches, although there was a small decline from after match 2 to after match 3 (3.3%; ES = −0.45 ± 0.62). There were progressive reductions in perceived well-being scores after matches 1 (ES = −0.38), 2 (ES = −0.70), and 3 (ES = −1.14). There were small to moderate associations between changes in fatigue measures and match running performance.

Conclusions:

Perceptual fatigue accumulates over consecutive tag football matches, although there were only marginal increases in neuromuscular fatigue. However, both neuromuscular and perceptual fatigue measures were found to contribute to reduced match running performance in the final match.

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Dac Minh Tuan Nguyen, Virgile Lecoultre, Yoshiyuki Sunami and Yves Schutz

Background:

Physical activity (PA) and related energy expenditure (EE) is often assessed by means of a single technique. Because of inherent limitations, single techniques may not allow for an accurate assessment both PA and related EE. The aim of this study was to develop a model to accurately assess common PA types and durations and thus EE in free-living conditions, combining data from global positioning system (GPS) and 2 accelerometers.

Methods:

Forty-one volunteers participated in the study. First, a model was developed and adjusted to measured EE with a first group of subjects (Protocol I, n = 12) who performed 6 structured and supervised PA. Then, the model was validated over 2 experimental phases with 2 groups (n = 12 and n = 17) performing scheduled (Protocol I) and spontaneous common activities in real-life condition (Protocol II). Predicted EE was compared with actual EE as measured by portable indirect calorimetry.

Results:

In protocol I, performed PA types could be recognized with little error. The duration of each PA type could be predicted with an accuracy below 1 minute. Measured and predicted EE were strongly associated (r = .97, P < .001).

Conclusion:

Combining GPS and 2 accelerometers allows for an accurate assessment of PA and EE in free-living situations.

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Ryu Nagahara, Alberto Botter, Enrico Rejc, Masaaki Koido, Takeshi Shimizu, Pierre Samozino and Jean-Benoit Morin

Purpose:

To test the concurrent validity of data from 2 different global positioning system (GPS) units for obtaining mechanical properties during sprint acceleration using a field method recently validated by Samozino et al.

Methods:

Thirty-two athletes performed maximal straight-line sprints, and their running speed was simultaneously measured by GPS units (sampling rate: 20 or 5 Hz) and either a radar or laser device (devices taken as references). Lower-limb mechanical properties of sprint acceleration (theoretical maximal force, theoretical maximal speed, maximal power) were derived from a modeling of the speed–time curves using an exponential function in both measurements. Comparisons of mechanical properties from 20- and 5-Hz GPS units with those from reference devices were performed for 80 and 62 trials, respectively.

Results:

The percentage bias showed a wide range of overestimation or underestimation for both systems (-7.9% to 9.7% and -5.1% to 2.9% for 20- and 5-Hz GPS), while the ranges of its 90% confidence limits for 20-Hz GPS were markedly smaller than those for 5-Hz GPS. These results were supported by the correlation analyses.

Conclusions:

Overall, the concurrent validity for all variables derived from 20-Hz GPS measurements was better than that obtained from the 5-Hz GPS units. However, in the current state of GPS devices’ accuracy for speed–time measurements over a maximal sprint acceleration, it is recommended that radar, laser devices, and timing gates remain the reference methods for implementing the computations of Samozino et al.

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Ademir F.S. Arruda, Christopher Carling, Vinicius Zanetti, Marcelo S. Aoki, Aaron J. Coutts and Alexandre Moreira

Purpose:

To analyze the effects of a very congested match schedule on the total distance (TD) covered, high-intensity-running (HIR) distance, and frequency of accelerations and body-load impacts (BLIs) performed in a team of under-15 soccer players (N = 10; 15.1 ± 0.2 y, 171.8 ± 4.7 cm, 61 ± 6.0 kg) during an international youth competition.

Methods:

Using global positioning systems, player performances were repeatedly monitored in 5 matches performed over 3 successive days.

Results:

Significant differences were observed between matches (P < .05) for the frequency of accelerations per minute, BLIs, and BLIs per minute. No differences were observed for the TD covered, TD run per minute, number of high-intensity runs, distance covered in HIR, per-minute peak running speed attained, or frequency of accelerations. The frequency of accelerations per minute decreased across the competition while BLIs were higher during the final than in all other matches.

Conclusions:

These results suggest that BLIs and acceleration might be used as an alternative means to represent the external load during congested match schedules rather than measures related to running speed or distance covered.

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Josh L. Secomb, Jeremy M. Sheppard and Ben J. Dascombe

Purpose:

To provide a descriptive and quantitative time–motion analysis of surfing training with the use of global positioning system (GPS) and heart-rate (HR) technology.

Methods:

Fifteen male surfing athletes (22.1 ± 3.9 y, 175.4 ± 6.4 cm, 72.5 ± 7.7 kg) performed a 2-h surfing training session, wearing both a GPS unit and an HR monitor. An individual digital video recording was taken of the entire surfing duration. Repeated-measures ANOVAs were used to determine any effects of time on the physical and physiological measures.

Results:

Participants covered 6293.2 ± 1826.1 m during the 2-h surfing training session and recorded measures of average speed, HRaverage, and HRpeak as 52.4 ± 15.2 m/min, 128 ± 13 beats/min, and 171 ± 12 beats/min, respectively. Furthermore, the relative mean times spent performing paddling, sprint paddling to catch waves, stationary, wave riding, and recovery of the surfboard were 42.6% ± 9.9%, 4.1% ± 1.2%, 52.8% ± 12.4%, 2.5% ± 1.9%, and 2.1% ± 1.7%, respectively.

Conclusion:

The results demonstrate that a 2-h surfing training session is performed at a lower intensity than competitive heats. This is likely due to the onset of fatigue and a pacing strategy used by participants. Furthermore, surfing training sessions do not appear to appropriately condition surfers for competitive events. As a result, coaches working with surfing athletes should consider altering training sessions to incorporate repeated-effort sprint paddling to more effectively physically prepare surfers for competitive events.

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Jason D. Vescovi

The aim of this study was to examine the impact of maximum sprint speed on peak and mean sprint speed during youth female field hockey matches. Two high-level female field hockey teams (U-17, n = 24, and U-21, n = 20) were monitored during a 4-game international test series using global position system technology and tested for maximum sprint speed. Dependent variables were compared using a 3-factor ANOVA (age group, position, and speed classification); effect sizes (Cohen d) and confidence limits were also calculated. Maximum sprint speed was similar between age groups and positions, with faster players having greater speed than slower players (29.3 ± 0.4 vs 27.2 ± 1.1 km/h). Overall, peak match speed in youth female field hockey players reaches approximately 90% of maximum sprint speed. Absolute peak match speed and mean sprint speed during matches were similar among the age groups (except match 1) and positions (except match 2); however, peak match speed was greater for faster players in matches 3 and 4. No differences were observed in the relative proportion for mean sprint speeds for age groups or positions, but slower players consistently displayed similar relative mean sprint speeds by using a greater proportion of their maximum sprint speed.

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Philip R. Hayes, Kjell van Paridon, Duncan N. French, Kevin Thomas and Dan A. Gordon

Purpose:

The aim of this study was to develop a laboratory-based treadmill simulation of the on-course physiological demands of an 18-hole round of golf and to identify the underlying physiological responses.

Methods:

Eight amateur golfers completed a round of golf during which heart rate (HR), steps taken, and global positioning system (GPS) data were assessed. The GPS data were used to create a simulated discontinuous round on a treadmill. Steps taken and HR were recorded during the simulated round.

Results:

During the on-course round, players covered a mean (±SD) of 8,251 ± 450 m, taking 12,766 ± 1,530 steps. The mean exercise intensity during the on-course round was 31.4 ± 9.3% of age-predicted heart rate reserve (%HRR) or 55.6 ± 4.4% of age-predicted maximum HR (%HRmax). There were no significant differences between the simulated round and the on-course round for %HRR (P = .537) or %HR max (P = .561) over the entire round or for each individual hole. Furthermore, there were no significant differences between the two rounds for steps taken. Typical error values for steps taken, HR, %HRmax, and %HRR were 1,083 steps, ±7.6 b·min-1, ±4.5%, and ±8.1%, respectively.

Conclusion:

Overall, the simulated round of golf successfully recreated the demands of an on-course round. This simulated round could be used as a research tool to assess the extent of fatigue during a round of golf or the impact of various interventions on golfers.

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Luis Suarez-Arrones, Javier Núñez, Eduardo Sáez de Villareal, Javier Gálvez, Gabriel Suarez-Sanchez and Diego Munguía-Izquierdo

Purpose:

To describe the repeated-high-intensity activity and internal training load of rugby sevens players during international matches and to compare the differences between the 1st and 2nd halves.

Methods:

Twelve international-level male rugby sevens players were monitored during international competitive matches (n = 30 match files) using global positioning system technology and heart-rate monitoring.

Results:

The relative total distance covered by the players throughout the match was 112.1 ± 8.4 m/min. As a percentage of total distance, 35.0% (39.2 ± 9.0 m/min) was covered at medium speed and 17.1% (19.2 ± 6.8 m/min) at high speed. A substantial decrease in the distance covered at >14.0 km/h and >18.0 km/h, the number of accelerations of >2.78 m/s and >4.0 m/s, repeated-sprint sequences interspersed with ≤60 s rest, and repeated-acceleration sequences interspersed with ≤30 s or ≤60 s rest was observed in the 2nd half compared with the 1st half. A substantial increase in the mean heart rate (HR), HRmax, percentage of time at >80% HRmax and at >90% HRmax, and Edwards training load was observed in the 2nd half compared with the 1st half.

Conclusion:

This study provides evidence of a pronounced reduction in high-intensity and repeated-highintensity activities and increases in internal training load in rugby sevens players during the 2nd half of international matches.

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Daniel Tan, Brian Dawson and Peter Peeling

Purpose:

This study aimed to quantify the hemolytic responses of elite female football (soccer) players during a typical weekly training session.

Methods:

Ten elite female football players (7 field players [FPs] and 3 goalkeepers [GKs]) were recruited from the Australian National Women’s Premier League and asked to provide a venous blood sample 30 min before and at the immediate conclusion of a typical weekly training session. During this training session, the players’ movement patterns were monitored via a 5-Hz global positioning system. The blood samples collected during the training session were analyzed for iron status via serum ferritin (SF) analysis, and the hemolytic response to training, via serum free hemoglobin (Hb) and haptoglobin (Hp) measurement.

Results:

50% of the participants screened were found to have a compromised iron stores (SF <35 μg/L). Furthermore, the posttraining serum free Hb levels were significantly elevated (P = .011), and the serum Hp levels were significantly decreased (P = .005), with no significant differences recorded between the FPs and GKs. However, the overall distance covered and the movement speed were significantly greater in the FPs.

Conclusions:

The increases in free Hb and decreases in Hp levels provide evidence that a typical team-sport training session may result in significant hemolysis. This hemolysis may primarily be a result of running-based movements in FPs and/or the plyometric movements in GKs, such as diving and tackling.