scholarly journals Countermovement-Jump-Phase Characteristics of Senior and Academy Rugby League Players

2017 ◽  
Vol 12 (6) ◽  
pp. 803-811 ◽  
Author(s):  
John J. McMahon ◽  
Shannon Murphy ◽  
Sophie J.E. Rej ◽  
Paul Comfort
Keyword(s):  
Movement Time ◽  
Rugby League ◽  
Neuromuscular Function ◽  
Countermovement Jump ◽  
Temporal Phase ◽  
Total Movement ◽  
Hip Extension ◽  
Total Movement Time ◽  
Maximal Effort ◽  
Insight Into

Purpose:Gross measures of countermovement-jump (CMJ) performance are commonly used to track maturational changes in neuromuscular function in rugby league (RL). The purpose of this study was to conduct both a gross and a more detailed temporal-phase analysis of the CMJ performances of senior and academy RL players, to provide greater insight into how neuromuscular function differs between these groups.Methods:Twenty senior and 14 academy (under-19) male RL players performed 3 maximal-effort CMJs on a force platform, with forward dynamics subsequently employed to allow gross performance measures and entire kinetic– and kinematic–time curves to be compared between groups.Results:Jump height (JH), reactive strength index modified, concentric displacement, and relative concentric impulse (C-IMP) were the only gross measures that were greater for senior players (d = 0.58–0.91) than for academy players. The relative force- and displacement–time curves were similar between groups, but the relative power– and velocity–time curves were greater (d = 0.59–0.97) for the senior players at 94–96% and 89–100% of the total movement time, respectively.Conclusions:The CMJ distinguished between senior and academy RL players, with seniors demonstrating greater JH through applying a larger C-IMP and thus achieving greater velocity throughout the majority of the concentric phase and at takeoff. Therefore, academy RL players should train to improve triple (ie, ankle, knee, and hip) extension velocity during the CMJ to bring their JH scores in line with those attained by senior players.

Investigating the Difficulty of One Degree of Freedom Positioning: Associating Movement Phases with Regions

2009 ◽  
Vol 53 (15) ◽  
pp. 965-969 ◽  
Author(s):  
Robert Pastel
Keyword(s):  
Movement Time ◽  
Touch Screen ◽  
Degree Of Freedom ◽  
One Dimension ◽  
Mouse Button ◽  
Total Movement ◽  
Remaining Time ◽  
Total Movement Time

Positioning an object within specified bounds is a common daily computer task, for example making selections using a touch screen or positioning icons relative to each other. This experiment measured times for participants ( n = 145) to position rectangular cursors with various widths, p, within rectangular targets with various tolerances, t, in one dimension. The analysis divides the total movement time into three parts, the time for the cursor to touch the target, the time to enter the target after touching, and the centering time, the remaining time for participants to indicate that the cursor is completely within the target by clicking on the mouse button. The time to touch the target was modeled well by the initial cursor-target separation, r2/sup> = 0.95. The entering time was modeled well by log2( p/t + 1), r2/sup> = 0.99, and the centering time was modeled well by r2/sup> = 0.94

Evaluation of the Helicopter Emergency Breathing Apparatus on Egress Performance

2020 ◽  
Vol 91 (12) ◽  
pp. 962-965
Author(s):  
Michael King ◽  
Elizabeth Sanli ◽  
Kaitlin Mugford ◽  
Stefanie Martina ◽  
Robert Brown ◽  
...  
Keyword(s):  
Movement Time ◽  
Prior Experience ◽  
Practical Significance ◽  
Escape Training ◽  
Specialized Training ◽  
Breathing Apparatus ◽  
Helicopter Landing ◽  
Total Movement ◽  
Sequence Performance ◽  
Total Movement Time

BACKGROUND: Emergency helicopter landing at sea is dangerous. Specialized training, known as helicopter underwater escape training (HUET), prepares occupants to quickly exit the helicopter, which often inverts and sinks. In most jurisdictions, helicopter occupants are equipped with a helicopter underwater egress breathing apparatus (HUEBA) to provide sufficient air for escape. HUET trainees report that the HUEBA is easy to use, but it is well known that learners are often overconfident in their judgement of learning. To better understand how the HUEBA affects HUET sequence performance, we investigated whether using the HUEBA influences the sequence movement time and number of errors.METHODS: Twelve participants (7 men and 5 women, mean age 25.33 9.57 SD) with no prior experience with HUET performed consecutive trials of the HUET sequence, 5 with the HUEBA and 5 without the HUEBA. Video of each trial recorded the total movement time and enabled movement time analyses of each component of the sequence: crossing arms, tucking the head, pushing the window, inserting the regulator, and releasing the seatbelt. These recordings were also used to score performance errors according to a checklist.RESULTS: Analyses revealed that using a HUEBA increased the total movement time and time to release the seatbelt by 0.36 and 0.39 s, respectively, in comparison to without the HUEBA.DISCUSSION: Our study illustrates that using the HUEBA during the HUET sequence increases total movement time and time to release the seatbelt. However, this difference is marginal and unlikely to have practical significance during underwater escape.King M, Sanli E, Mugford K, Martina S, Brown R, Carnahan H. Evaluation of the helicopter emergency breathing apparatus on egress performance. Aerosp Med Hum Perform. 2020; 91(12):962965.

scholarly journals Factors Affecting the Anthropometric and Physical Characteristics of Elite Academy Rugby League Players: A Multiclub Study

2019 ◽  
Vol 14 (7) ◽  
pp. 958-965 ◽  
Author(s):  
Nick Dobbin ◽  
Jamie Highton ◽  
Samantha Louise Moss ◽  
Craig Twist
Keyword(s):  
Body Mass ◽  
Training Programs ◽  
Rugby League ◽  
Physical Characteristics ◽  
Countermovement Jump ◽  
Factors Affecting ◽  
Competitive Season ◽  
Insight Into ◽  
Ranking Position ◽  
Super League

Purpose: To investigate the factors affecting the anthropometric and physical characteristics of elite academy rugby league players. Methods: One hundred ninety-seven elite academy rugby league players (age = 17.3 [1.0] y) from 5 Super League clubs completed measures of anthropometric and physical characteristics during a competitive season. The interaction between and influence of contextual factors on characteristics was assessed using linear mixed modeling. Results: All physical characteristics improved during preseason and continued to improve until midseason, whereafter 10-m sprint (η2 = .20 cf .25), countermovement jump (CMJ) (η2 = .28 cf .30), and prone Yo-Yo Intermittent Recovery (Yo-Yo IR) test (η2 = .22 cf .54) performance declined. Second (η2 = .17) and third (η2 = .16) -year players were heavier than first-years, whereas third-years had slower 10-m sprint times (η2 = .22). Large positional variability was observed for body mass, 20-m sprint time, medicine-ball throw, CMJ, and prone Yo-Yo IR1. Compared with bottom-ranked teams, top-ranked teams demonstrated superior 20-m (η2 = −.22) and prone Yo-Yo IR1 (η2 = .26) performance, whereas middle-ranked teams reported higher CMJ height (η2 = .26) and prone Yo-Yo IR1 distance (η2 = .20) but slower 20-m sprint times (η2 = .20). Conclusion: These findings offer practitioners who design training programs for academy rugby league players insight into the relationships between anthropometric and physical characteristics and how they are influenced by playing year, league ranking, position, and season phase.

Control of sequential movements: evidence for generalized motor programs

1984 ◽  
Vol 52 (5) ◽  
pp. 787-796 ◽  
Author(s):  
M. C. Carter ◽  
D. C. Shapiro
Keyword(s):  
Temporal Pattern ◽  
Peak Velocity ◽  
Movement Time ◽  
Movement Speed ◽  
Relative Timing ◽  
Motor Programs ◽  
Pronator Teres ◽  
Movement Sequence ◽  
Total Movement ◽  
Total Movement Time

The neuromotor processes underlying the control of rapid sequential limb movements were investigated. Subjects learned to pronate and supinate their forearms rapidly to four target locations in a specific spatio-temporal pattern under two movement-time conditions. The response sequence was first performed in a total movement time of 600 ms. Subjects were then told to produce the movement as quickly as possible while ignoring any timing pattern that they had previously learned. Electromyographic (EMG) signals were recorded from the biceps brachii and pronator teres muscles. Kinematic and EMG analyses were performed to investigate the temporal characteristics underlying the two movement-time conditions. When subjects produced the response as quickly as possible, average movement time to perform each reversal movement decreased while average peak velocity increased. Average total movement time was reduced by approximately 100 ms. Although movement time decreased, the proportion of total time to perform each movement of the sequence remained essentially invariant between movement-time conditions. Similar results were obtained for velocity. The time at which peak velocity was achieved occurred earlier in absolute time, although when normalized to the proportion of total movement time, the time to reach peak velocity was also invariant. Thus subjects proportionally compressed the entire movement sequence in time. The EMG analysis demonstrated that total EMG time decreased 89 ms on the average when subjects sped up the movement sequence. Thus average burst durations for both the biceps and pronator teres muscles decreased when movement speed increased. When burst durations were normalized to a proportion of total EMG time, the average proportion of time each muscle was active remained invariant. Therefore, the temporal pattern of activity for the biceps and pronator teres muscles were also proportionally compressed. The present experiment provided additional evidence for the structure of generalized motor programs consisting of invariant and variant features. Movement speed was considered a variant feature, which is specified each time the program is executed. Relative timing, the proportion of total time to produce each segment of the response, was considered to be an invariant feature and inherent in the structure of the motor program. Support for the invariance of relative timing was observed at both the kinematic and neuromuscular levels of analyses. Alternative models (9-11, 24) were found inadequate to account for the invariance of relative timing with the variation in movement time observed in the present experiment.

scholarly journals Stereoacuity predicts total movement time in a fronto-parallel prehension task

2018 ◽  
Vol 18 (10) ◽  
pp. 60
Author(s):  
Angelica Godinez ◽  
Alyson Kishi ◽  
Mariela Hernandez ◽  
Preeti Verghese ◽  
Dennis Levi
Keyword(s):  
Movement Time ◽  
Total Movement ◽  
Total Movement Time

scholarly journals Vertical Jump Testing in Rugby League: A Rationale for Calculating Take-Off Momentum

2020 ◽  
Vol 36 (6) ◽  
pp. 370-374
Author(s):  
John J. McMahon ◽  
Jason P. Lake ◽  
Nicholas J. Ripley ◽  
Paul Comfort
Keyword(s):  
Positive Relationship ◽  
Vertical Jump ◽  
Rugby League ◽  
Force Platform ◽  
Prediction Equations ◽  
Countermovement Jump ◽  
Common Variance ◽  
Calculated Mass ◽  
Maximal Effort

The purpose of this study was to determine the usefulness of calculating jump take-off momentum in rugby league (RL) by exploring its relationship with sprint momentum, due to the latter being an important attribute of this sport. Twenty-five male RL players performed 3 maximal-effort countermovement jumps on a force platform and 3 maximal effort 20-m sprints (with split times recorded). Jump take-off momentum and sprint momentum (between 0 and 5, 5 and 10, and 10 and 20 m) were calculated (mass multiplied by velocity) and their relationship determined. There was a very large positive relationship between both jump take-off and 0- to 5-m sprint momentum (r = .781, P < .001) and jump take-off and 5- to 10-m sprint momentum (r = .878, P < .001). There was a nearly perfect positive relationship between jump take-off and 10- to 20-m sprint momentum (r = .920, P < .001). Jump take-off and sprint momentum demonstrated good–excellent reliability and very large–nearly perfect associations (61%–85% common variance) in an RL cohort, enabling prediction equations to be created. Thus, it may be practically useful to calculate jump take-off momentum as part of routine countermovement jump testing of RL players and other collision-sport athletes to enable the indirect monitoring of sprint momentum.

Age Differences in Integration of Components of a Motor Task

1975 ◽  
Vol 41 (1) ◽  
pp. 211-215 ◽  
Author(s):  
John I. Todor
Keyword(s):  
Age Differences ◽  
Movement Time ◽  
Age Groups ◽  
Motor Task ◽  
Linear Component ◽  
Learning And Development ◽  
Total Movement ◽  
Component C ◽  
High Degree ◽  
Total Movement Time

To study effects of practice on the ability of 6-, 11-, and 18-yr.-old Ss to integrate the components of the Rho task 3 groups of 50 boys performed 30 consecutive trials. (a) With practice all age groups improved in total movement time; (b) 11-yr.-old Ss attained the 18-yr.-olds' level of performance in both components, initial differences existing only in the linear component; (c) relative to the 18-yr.-old Ss, the 6-yr.-olds achieved proportionally less improvement in the linear component; (d) unlike 11- and 18-yr.-old Ss, the 6-yr.-olds evidenced increasing specificity of task components across trials. Unlike the two older age groups, the 6-yr.-old Ss were unable to achieve a high degree of integration of task components. The findings were discussed in light of Pascual-Leone's neo-Piagetian model of learning and development.

scholarly journals Aging Does Not Affect Beta Modulation during Reaching Movements

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Serena Ricci ◽  
Ramtin Mehraram ◽  
Elisa Tatti ◽  
Aaron B. Nelson ◽  
Martina Bossini-Baroggi ◽  
...  
Keyword(s):  
Modulation Depth ◽  
Movement Time ◽  
Peak Latency ◽  
Reaching Movements ◽  
Performance Indices ◽  
Reaching Task ◽  
Beta Power ◽  
Total Movement ◽  
Older Subjects ◽  
Highly Correlated

During movement, modulation of beta power occurs over the sensorimotor areas, with a decrease just before its start (event-related desynchronization, ERD) and a rebound after its end (event-related synchronization, ERS). We have recently found that the depth of ERD-to-ERS modulation increases during practice in a reaching task and the following day decreases to baseline levels. Importantly, the magnitude of the beta modulation increase during practice is highly correlated with the retention of motor skill tested the following day. Together with other evidence, this suggests that the increase of practice-related modulation depth may be the expression of sensorimotor cortex’s plasticity. Here, we determine whether the practice-related increase of beta modulation depth is equally present in a group of younger and a group of older subjects during the performance of a 30-minute block of reaching movements. We focused our analyses on two regions of interest (ROIs): the left sensorimotor and the frontal region. Performance indices were significantly different in the two groups, with the movements of older subjects being slower and less accurate. Importantly, both groups presented a similar increase of the practice-related beta modulation depth in both ROIs in the course of the task. Peak latency analysis revealed a progressive delay of the ERS peak that correlated with the total movement time. Altogether, these findings support the notion that the depth of beta modulation in a reaching movement task does not depend on age and confirm previous findings that only ERS peak latency but not ERS magnitude is related to performance indices.

Assessment of an International Breaststroke Swimmer Using a Race Readiness Test

2009 ◽  
Vol 4 (1) ◽  
pp. 139-143
Author(s):  
Kevin G. Thompson ◽  
Stephen W. Garland
Keyword(s):  
Priming Effect ◽  
Training Data ◽  
Step Test ◽  
Exercise Protocol ◽  
Incremental Step ◽  
Technical Readiness ◽  
Competitive Swimmers ◽  
Maximal Effort ◽  
Insight Into

Competitive swimmers routinely undertake a 7 X 200-m incremental step test to evaluate their fitness and readiness to compete.1 An exercise protocol more closely replicating competition swimming speeds may provide further insight into the swimmer’s physiological and technical readiness for competition. This case study reports data over a 3-year period from 11 Race Readiness Tests, which were completed, in addition to the 7 X 200-m test, as an attempt to provide the swimmer and coach with a fuller assessment. For this individual, data provided objective information from which to assess training status and race readiness following a transition from 200-m to 100-m race training. Data also raised a question as to whether a 100-m maximal effort 10 minutes before another one actually enhances performance owing to a priming effect.

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