Search Results

You are looking at 11 - 20 of 40 items for :

  • "velocity–time" x
Clear All
Restricted access

Nicola Furlan, Mark Waldron, Kathleen Shorter, Tim J. Gabbett, John Mitchell, Edward Fitzgerald, Mark A. Osborne and Adrian J. Gray

Purpose:

To investigate temporal variation in running intensity across and within halves and evaluate the agreement between match-analysis indices used to identify fluctuations in running intensity in rugby sevens.

Methods:

Data from a 15-Hz global positioning system (GPS) were collected from 12 elite rugby sevens players during the IRB World Sevens Series (N = 21 full games). Kinematic (eg, relative distance [RD]) and energetic (eg, metabolic power [MP]) match-analysis indices were determined from velocity–time curves and used to investigate between-halves variations. Mean MP and RD were used to identify peak 2-minute periods of play. Adjacent 2-minute periods (prepeak and postpeak) were compared with peak periods to identify changes in intensity. MP and RD were expressed relative to maximal oxygen uptake (V̇O2max) and speed at V̇O2max, respectively, and compared in their ability to describe the intensity of peak periods and their temporal occurrence.

Results:

Small to moderate reductions were present for kinematic (RD; 8.9%) and energetic (MP; 6%) indices between halves. Peak periods (RD = 130 m/min, MP =13 W/kg) were higher (P < .001) than the match average (RD = 94 m/min, MP = 9.5 W/kg) and the prepeak and postpeak periods (P < .001). RD underestimated the intensity of peak periods compared with MP (bias 16%, limits of agreement [LoA] ± 6%). Peak periods identified by RD and MP were temporally dissociated (bias 21 s, LoA ± 212 s).

Conclusions:

The findings suggest that running intensity varies between and within halves; however, the index used will influence both the magnitude and the temporal identification of peak periods.

Restricted access

Remco Polman, Jonathan Bloomfield and Andrew Edwards

Purpose:

The main objective of this study was to investigate the efficacy of both programmed (speed, agility, and quickness; SAQ) and random (small-sided games; SSG) conditioning methods on selected neuromuscular and physical performance variables.

Methods:

Twenty volunteers (21.1 ± 4.0 y, 1.71 ± 0.09 m, 66.7 ± 9.9 kg; mean ± SD) completed the study. The study design used two physically challenging periodized experimental conditions (SAQ and SSG conditions) and a non exercise control condition (CON). Participants engaged in 12.2 ± 2.1 h of directed physical conditioning. All participants had at least 24 h of recovery between conditioning sessions, and each 1-h session included 15 min of general warm-up and a 45-min exercise session. Participants completed a battery of tests (15-m sprint, isokinetic flexion/extension, depth jump) before and following the training program.

Results:

There was a 6.9% (95% CI: -4.4 to 18.3) greater improvement in 5-m acceleration time and 4.3% (95% CI: -0.9 to 9.5) in 15-m mean running velocity time for the SAQ group compared with the SSG group. In addition, increases in maximal isokinetic concentric strength for both the flexor and extensor muscles, with the exception of 180 °/s flexion, were greater in the SAQ than SSG condition. The SAQ group also showed 19.5% (95% CI: -11.2 to 50.2) greater gain in reactive strength (contact time depth jump) and 53.8% (95% CI: 11.2 to 98.6) in mean gastrocnemius medialis activity in comparison with SSG.

Conclusions:

SAQ training should benefit the physical conditioning programs of novice players performing invasion games.

Restricted access

Jace A. Delaney, Tannath J. Scott, Heidi R. Thornton, Kyle J.M. Bennett, David Gay, Grant M. Duthie and Ben J. Dascombe

Rugby league coaches often prescribe training to replicate the demands of competition. The intensities of running drills are often monitored in comparison with absolute match-play measures. Such measures may not be sensitive enough to detect fluctuations in intensity across a match or to differentiate between positions.

Purpose:

To determine the position- and duration-specific running intensities of rugby league competition, using a moving-average method, for the prescription and monitoring of training.

Methods:

Data from a 15-Hz global positioning system (GPS) were collected from 32 professional rugby league players across a season. The velocity–time curve was analyzed using a rolling-average method, where maximum values were calculated for 10 different durations, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 min, for each player across each match.

Results:

There were large differences between the 1- and 2-min rolling averages and all other rolling-average durations. Smaller differences were observed for rolling averages of greater duration. Fullbacks maintained a greater velocity than outside backs and middle and edge forwards over the 1- and 2-min rolling averages (ES 0.8−1.2, P < .05). For rolling averages 3 min and greater, the running demands of the fullbacks were greater than those of the middle forwards and outside backs (ES 1.1−1.4, P < .05).

Conclusions:

These findings suggest that the running demands of rugby league fluctuate vastly across a match. Fullbacks were the only position to exhibit a greater running intensity than any other position, and therefore training prescription should reflect this.

Restricted access

Jean-Benoît Morin, George Petrakos, Pedro Jiménez-Reyes, Scott R. Brown, Pierre Samozino and Matt R. Cross

Background:

Sprint running acceleration is a key feature of physical performance in team sports, and recent literature shows that the ability to generate large magnitudes of horizontal ground-reaction force and mechanical effectiveness of force application are paramount. The authors tested the hypothesis that very-heavy loaded sled sprint training would induce an improvement in horizontal-force production, via an increased effectiveness of application.

Methods:

Training-induced changes in sprint performance and mechanical outputs were computed using a field method based on velocity–time data, before and after an 8-wk protocol (16 sessions of 10- × 20-m sprints). Sixteen male amateur soccer players were assigned to either a very-heavy sled (80% body mass sled load) or a control group (unresisted sprints).

Results:

The main outcome of this pilot study is that very-heavy sled-resisted sprint training, using much greater loads than traditionally recommended, clearly increased maximal horizontal-force production compared with standard unloaded sprint training (effect size of 0.80 vs 0.20 for controls, unclear between-groups difference) and mechanical effectiveness (ie, more horizontally applied force; effect size of 0.95 vs –0.11, moderate between-groups difference). In addition, 5-m and 20-m sprint performance improvements were moderate and small for the very-heavy sled group and small and trivial for the control group, respectively.

Practical Applications:

This brief report highlights the usefulness of very-heavy sled (80% body mass) training, which may suggest value for practical improvement of mechanical effectiveness and maximal horizontal-force capabilities in soccer players and other team-sport athletes.

Results:

This study may encourage further research to confirm the usefulness of very-heavy sled in this context.

Restricted access

Pedro G. Morouço, Tiago M. Barbosa, Raul Arellano and João P. Vilas-Boas

interface was used to acquire, display, and process pairwise velocity–time data on-line during the trials. To transfer data from the speedometer to the software application, a 12-bit resolution acquisition card (USB-6008; National Instruments Corp) was used as well. For the maximal effort 30-second tethered

Restricted access

Ramón Marcote-Pequeño, Amador García-Ramos, Víctor Cuadrado-Peñafiel, Jorge M. González-Hernández, Miguel Ángel Gómez and Pedro Jiménez-Reyes

providing more meaningful data to implement individualized training programs. 12 , 13 Namely, the force and velocity data collected during vertical jumps performed against 2 or more loads 14 , 15 and the displacement–time (or velocity–time) data recorded during sprint running 16 , 17 can be used to model

Restricted access

Reed D. Gurchiek, Hasthika S. Rupasinghe Arachchige Don, Lasanthi C. R. Pelawa Watagoda, Ryan S. McGinnis, Herman van Werkhoven, Alan R. Needle, Jeffrey M. McBride and Alan T. Arnholt

metrics clear—increases in v 0 or the ratio v 0 / τ are associated with improved sprint performance. In practice, these constants are estimated for an athlete using position–time or velocity–time data and Equation  3 or 2 , respectively. 1 – 5 , 7 Experiments have been conducted for smartphone

Restricted access

Caleb D. Bazyler, Satoshi Mizuguchi, Ashley A. Kavanaugh, John J. McMahon, Paul Comfort and Michael H. Stone

obtain a velocity–time trace. Peak power was the maximal value obtained from the product of the velocity–time and force–time traces. The mean of the 2 best trials within a 2-cm difference in JH was used for analysis. Additional trials were performed when the difference between 2 trials was greater than 2

Restricted access

Jesús J. Ruiz-Navarro, Pedro G. Morouço and Raúl Arellano

’s hip by way of a belt, recording at 200 Hz. Data were recorded, converted (signal frame MF020; Sportmetrics, Valencia, Spain), and exported to the software (SignalFrame version 2.00; Sportmetrics). Total time and SR were recorded using automatic swimming performance analysis. Force–time and velocity–time

Restricted access

Adam Culiver, J. Craig Garrison, Kalyssa M. Creed, John E. Conway, Shiho Goto and Sherry Werner

collection. Kinematic variables used for analysis in the current study included stride length, time to maximal humerus velocity, time to maximal thorax velocity, and time from SFC to maximal knee flexion. All kinematic data were analyzed using a 9-camera Qualisys (Göteborg, Sweden) camera system sampling at