Individuals with multiple sclerosis (MS) often have poor balance control that is especially apparent during dynamic tasks such as gait initiation (GI). The purpose of this study was to investigate how balance symptoms due to MS alter spatiotemporal variables, coordination, and temporal margins within the stability boundary during gait initiation. Twelve women with MS (Expanded Disability Status Scale [EDSS] mean = 4.0, SD = 1.4) and 12 women without MS (control group) initiated gait at their preferred speed. MS participants attained a slower anterior velocity because of smaller anterior center of mass displacements and took longer to complete the initiation of gait than the control group. MS participants exhibited a smaller posterior shift in center of pressure during GI and stepped with a longer dual support time than the control group. However, these changes may be due to differences in initiation velocity. Relative timing analysis showed invariance in postural and locomotor phases of gait initiation between groups. The MS group showed different coordination between anterior-posterior and medio-lateral center of pressure components while increasing temporal margins to the posterior and lateral stability boundaries in comparison with the control group. Overall, during gait initiation at their preferred speed the MS participants adopted a functional strategy that produces lower speed and reduced proximity to the stability boundaries prior to stepping.
Jebb G. Remelius, Joseph Hamill, Jane Kent-Braun and Richard E.A. Van Emmerik
James J. Malone, Ric Lovell, Matthew C. Varley and Aaron J. Coutts
Athlete-tracking devices that include global positioning system (GPS) and microelectrical mechanical system (MEMS) components are now commonplace in sport research and practice. These devices provide large amounts of data that are used to inform decision making on athlete training and performance. However, the data obtained from these devices are often provided without clear explanation of how these metrics are obtained. At present, there is no clear consensus regarding how these data should be handled and reported in a sport context. Therefore, the aim of this review was to examine the factors that affect the data produced by these athlete-tracking devices and to provide guidelines for collecting, processing, and reporting of data. Many factors including device sampling rate, positioning and fitting of devices, satellite signal, and data-filtering methods can affect the measures obtained from GPS and MEMS devices. Therefore researchers are encouraged to report device brand/model, sampling frequency, number of satellites, horizontal dilution of precision, and software/firmware versions in any published research. In addition, details of inclusion/exclusion criteria for data obtained from these devices are also recommended. Considerations for the application of speed zones to evaluate the magnitude and distribution of different locomotor activities recorded by GPS are also presented, alongside recommendations for both industry practice and future research directions. Through a standard approach to data collection and procedure reporting, researchers and practitioners will be able to make more confident comparisons from their data, which will improve the understanding and impact these devices can have on athlete performance.
Kara K. Palmer and Ali Brian
The Test of Gross Motor Development, 2nd edition (TGMD-2), is one of the most widely used measures of motor skill competence. The purpose of this study was to examine if differences in scores exist between expert and novice coders on the TGMD-2 (Ulrich, 2000).
Three coders, one expert and two novices, reviewed and scored young children’s (N = 43; Boys = 57%; Mage = 4.88, SD = 0.28) TGMD-2 data. The kappa statistic was used to determine agreement between expert and novice coders on the locomotor and object control subscale of the TGMD-2. Independent samples t tests and percent differences were then used to examine scoring differences for each of the twelve skills.
Results support that expert and novice coders do not demonstrate significant agreement when scoring the TGMD-2 except for when scoring the kick (t 41 = –1.3, p = .2) and the gallop (t 41= –1.7, p = .09).
This work demonstrates that more stringent or consistent training regimens are needed before allowing novices to code TGMD-2 data.
Martin Buchheit and Ben Michael Simpson
With the ongoing development of microtechnology, player tracking has become one of the most important components of load monitoring in team sports. The 3 main objectives of player tracking are better understanding of practice (provide an objective, a posteriori evaluation of external load and locomotor demands of any given session or match), optimization of training-load patterns at the team level, and decision making on individual players’ training programs to improve performance and prevent injuries (eg, top-up training vs unloading sequences, return to play progression). This paper discusses the basics of a simple tracking approach and the need to integrate multiple systems. The limitations of some of the most used variables in the field (including metabolic-power measures) are debated, and innovative and potentially new powerful variables are presented. The foundations of a successful player-monitoring system are probably laid on the pitch first, in the way practitioners collect their own tracking data, given the limitations of each variable, and how they report and use all this information, rather than in the technology and the variables per se. Overall, the decision to use any tracking technology or new variable should always be considered with a cost/benefit approach (ie, cost, ease of use, portability, manpower/ability to affect the training program).
Joseph F. Seay, Jeffery M. Haddad, Richard E.A. van Emmerik and Joseph Hamill
Increases in movement variability have previously been observed to be a hallmark property of cooraination changes between coupled oscillators that occur as movement frequency is scaled. Prior research on the walk-run transition in human locomotion has also demonstrated increases in variability around the transition region, supporting predictions of nonequilibrium phase transitions (Diedrich & Warren, 1995). The current study examined the coordinative patterns of both intra- and inter-limb couplings around the walk-run transition using two different temporal manipulations of locomotor velocity as a control parameter in healthy young participants (N = 11). Coordination variability did not increase before the transition. The nature of the change in continuous relative phase variability between gait modes was coupling-specific, and varying the time spent at each velocity did not have an overall effect on gait transition dynamics. Lower extremity inter-limb coordination dynamics were more sensitive to changes in treadmill velocity than intra-limb coordination. The results demonstrate the complexity of segmental coordination change in human locomotion, and question the applicability of dynamical bimanual coordination models to human gait transitions.
Anthony D. Okely, Michael L. Booth and John W. Patterson
This study investigated a possible relationship between cardiorespiratory endurance and fundamental movement skill proficiency among adolescents. Locomotor (run and jump) and object-control (catch, throw, kick, and strike) skills and cardiorespiratory endurance, indirectly measured using the Multistage Fitness Test (MFT) or PACER, were assessed in 2,026 boys and girls in Grade 8 (mean age = 13.3 years) and Grade 10 (mean age = 15.3 years), who were part of a randomly selected sample who agreed to participate in the New South Wales Schools Fitness and Physical Activity Survey, 1997. Boys had higher levels of cardiorespiratory endurance and were more competent than girls on 5 out of 6 skills. Grade 10 students were better on all skills and were aerobically fitter than Grade 8 students. All six skills and a skills index were related to the number of laps completed on the MFT. The six skills explained 20% and 26% of the variance in the number of laps completed on the MFT for Grade 8 and Grade 10 girls, respectively, and 12% and 17% for Grade 8 and Grade 10 boys, respectively. This finding can be interpreted as evidence of a relationship between cardiorespiratory endurance and fundamental movement skills among adolescents. Further studies are recommended to determine if improved movement skills in adolescents can promote cardiorespiratory endurance.
Samuel W. Logan, E. Kipling Webster, Nancy Getchell, Karin A. Pfeiffer and Leah E. Robinson
The purpose of this review is to synthesize the evidence of the relationship between fundamental motor skills (FMS) competence and physical activity by qualitatively describing results from 13 studies that met rigorous inclusion criteria. Inclusion criteria: (a) published in a peer-review journal, (b) participants were between the ages of 3–18, (c) participants were typically developing, (d) FMS was measured by a process-oriented assessment, (e) assessed physical activity, (f) related FMS and physical activity through statistical procedures, and (g) printed in English. Databases were searched for relevant articles using key terms related to FMS and physical activity. Evidence suggested low to moderate relationships between FMS competence and physical activity in early childhood (r = .16 to .48; R2 = 3–23%, 4 studies), low to high relationships in middle to late childhood (r = .24 to .55; R2 = 6–30%, 7 studies), and low to moderate relationships in adolescence (r = .14 to .35; R2 = 2–12.3%, 2 studies). Across ages, object control skills and locomotor skills were more strongly related to physical activity for boys and girls, respectively. Future research should emphasize experimental and longitudinal research designs to provide further understanding of the relationship between FMS competence and physical activity.
Roberta L. Pohlman and Larry D. Isaacs
This preliminary investigation examined the potential effects of low birth weight on motor performance in children. Seventeen pairs of children were matched by age and placed in one of five age groups (5-9 years). One of each pair weighed 2,200 grams or less at birth (low birth weight, LBW) and the other weighed more than 2,200 grams at birth (normal birth weight, NBW). Three types of data were collected: motor development data, reaction time data, and anthropometric data. Nine paired t tests were performed. To control for alpha level inflation, the Bonferroni technique was employed. The two groups did not differ significantly in present body weight. Tests of gross motor development found the NBW group to be more advanced in both locomotor skills and object control skills. With regard to triceps skinfold, again the NBW group was found to have greater values. No other between-group measurements of body composition were significant. In addition, girls were significantly higher than boys in percent body fat. These preliminary results suggest the LBW children lag behind their NBW peers in the development of the basic fundamental motor skills.
Jared A. Bailey, Paul B. Gastin, Luke Mackey and Dan B. Dwyer
Most previous investigations of player load in netball have used subjective methodologies, with few using objective methodologies. While all studies report differences in player activities or total load between playing positions, it is unclear how the differences in player activity explain differences in positional load.
To objectively quantify the load associated with typical activities for all positions in elite netball.
The player load of all playing positions in an elite netball team was measured during matches using wearable accelerometers. Video recordings of the matches were also analyzed to record the start time and duration of 13 commonly reported netball activities. The load associated with each activity was determined by time-aligning both data sets (load and activity).
Off-ball guarding produced the highest player load per instance, while jogging produced the greatest player load per match. Nonlocomotor activities contributed least to total match load for attacking positions (goal shooter [GS], goal attack [GA], and wing attack [WA]) and most for defending positions (goalkeeper [GK], goal defense [GD], and wing defense [WD]). Specifically, centers (Cs) produced the greatest jogging load, WA and WD accumulated the greatest running load, and GS and WA accumulated the greatest shuffling load. WD and Cs accumulated the greatest guarding load, while WD and GK accumulated the greatest off-ball guarding load.
All positions exhibited different contributions from locomotor and nonlocomotor activities toward total match load. In addition, the same activity can have different contributions toward total match load, depending on the position. This has implications for future design and implementation of position-specific training programs.
Andrew A. Dingley, David B. Pyne and Brendan Burkett
To characterize relationships between propulsion, anthropometry, and performance in Paralympic swimming.
A cross-sectional study of swimmers (13 male, 15 female) age 20.5 ± 4.4 y was conducted. Subject locomotor categorizations were no physical disability (n = 8, classes S13–S14) and low-severity (n = 11, classes S9–S10) or midseverity disability (n = 9, classes S6–S8). Full anthropometric profiles estimated muscle mass and body fat, a bilateral swim-bench ergometer quantified upper-body power production, and 100-m time trials quantified swimming performance.
Correlations between ergometer mean power and swimming performance increased with degree of physical disability (low-severity male r = .65, ±0.56, and female r = .68, ±0.64; midseverity, r = .87, ±0.41, and r = .79, ±0.75). The female midseverity group showed nearperfect (positive) relationships for taller swimmers’ (with a greater muscle mass and longer arm span) swimming faster, while for female no- and low-severity-disability groups, greater muscle mass was associated with slower velocity (r = .78, ±0.43, and r = .65, ±0.66). This was supported with lighter females (with less frontal surface area) in the low-severity group being faster (r = .94, ±0.24). In a gender contrast, low-severity males with less muscle mass (r = -.64, ±0.56), high skinfolds (r = .78, ±0.43), a longer arm span (r = .58, ±0.60) or smaller frontal surface area (r = -.93, ±0.19) were detrimental to swimming-velocity production.
Low-severity male and midseverity female Paralympic swimmers should be encouraged to develop muscle mass and upper-body power to enhance swimming performance. The generalized anthropometric measures appear to be a secondary consideration for coaches.