Kevin L. Lamb

Concurrent validity and test–retest reliability of a global positioning system (GPS) and timing gates to assess sprint performance variables

Abstract There has been no previous investigation of the concurrent validity and reliability of the current 5 Hz global positioning system (GPS) to assess sprinting speed or the reliability of integrated GPS–accelerometer technology. In the present study, we wished to determine: (1) the concurrent validity and reliability of a GPS and timing gates to measure sprinting speed or distance, and (2) the reliability of proper accelerations recorded via GPS–accelerometer integration. Nineteen elite youth rugby league players performed two over-ground sprints and were simultaneously assessed using GPS and timing gates. The GPS measurements systematically underestimated both distance and timing gate speed. The GPS measurements were reliable for all variables of distance and speed (coefficient of variation [CV] = 1.62% to 2.3%), particularly peak speed (95% limits of agreement [LOA] = 0.00 ± 0.8 km · h−1; CV = 0.78%). Timing gates were more reliable (CV = 1% to 1.54%) than equivalent GPS measurements. Accelerometer measurements were least reliable (CV = 4.69% to 5.16%), particularly for the frequency of proper accelerations (95% LOA = 1.00 ± 5.43; CV = 14.12%). Timing gates and GPS were found to reliably assess speed and distance, although the validity of the GPS remains questionable. The error found in accelerometer measurements indicates the limits of this device for detecting changes in performance.

Validity of a Pictorial Perceived Exertion Scale for Effort Estimation and Effort Production During Stepping Exercise in Adolescent Children

Recent developments in the study of paediatric effort perception have continued to emphasize the importance of child-specific rating scales. The purpose of this study was to examine the validity of an illustrated 1–10 perceived exertion scale: the Pictorial Children’s Effort Rating Table (PCERT). Four class groups comprising 104 children, 27 boys and 29 girls, aged 12.1±0.3 years and 26 boys, 22 girls, aged 15.3±0.2 years were selected from two schools and participated in the initial development of the PCERT. Subsequently, 48 of these children, 12 boys and 12 girls from each age group, were randomly selected to participate in the PCERT validation study. Exercise trials were divided into two phases and took place 7 to 10 days apart. During Phase 1, children completed 5 three minute incremental stepping exercise bouts interspersed with two minute recovery periods. Heart rate (HR) and ratings of exertion were recorded during the final 15 seconds of each exercise bout. In Phase 2 the children were asked to regulate their exercising effort during 4 four minute bouts of stepping so that it matched randomly prescribed PCERT levels (3, 5, 7 and 9). Analysis of data from phase 1 yielded significant (p<0.01) relationships between perceived and objective (HR) effort measures for girls. In addition, the main effects of exercise intensity on perceived exertion and HR were significant (p<0.01); perceived exertion increased as exercise intensity increased and this was reflected in simultaneous significant rises in HR. During phase 2, HR and estimated power output (POapprox) produced at each of the four prescribed effort levels were significantly different (p<0.01). The children in this study were able to discriminate between four different exercise intensities and regulate their exercise intensity according to four prescribed levels of perceived exertion. In seeking to contribute towards children’s recommended physical activity levels and helping them understand how to self-regulate their activity, the application of the PCERT within the context of physical education is a desirable direction for future research.

The movement characteristics of English Premiership rugby union players

Abstract The purpose of this investigation was to quantify the movement characteristics of elite rugby union players during competitive play and identify whether position-related differences exist. Ninety-eight elite players from eight English Premiership Clubs were tracked using global positioning systems (GPS) during 44 competitive matches throughout the 2010/2011 season. Player positions were defined as: (1) Backs or Forwards; (2) Front, Second and Back Rows, Scrum Half, Inside and Outside Backs; (3) 15 individual positions (numbers 1–15). Analysis revealed the game is predominantly played at low speeds with little distance covered ‘sprinting’ by either the Backs (50 ± 76 m) or the Forwards (37 ± 64 m). The Backs travelled greater (P < 0.05) absolute and relative distances than the Forwards. The Scrum Half covered the greatest total distance during a match (7098 ± 778 m) and the Front Row the least (5158 ± 200 m). The Back Row covered the greatest distances at ‘sprinting’ speeds, particularly the number 8 position (77 m). These findings reflect notable differences in the movement characteristics displayed by elite rugby union players in specific positional roles, and reinforce the contemporary view that training programmes for such players ought to be structured with this in mind.

The Assessment of Physical Activity by Leisure-Time Physical Activity Questionnaires

SummaryThe assessment of physical activity by questionnaire is currently the most popular and practical method of quantifying physical activity levels. Many questionnaires, past and present, have considered overall or habitual physical activity, which includes occupational (or nonleisure) activity. Others have focused specifically on leisure-time physical activity (LTPA) owing to the recognition of its dominating contribution to the total physical activity of developed populations. This review covers questionnaires that wholly or in part attend to LTPA levels.Typically, self-complete or interviewer-administered questionnaires record information on the types, frequency and duration of activities performed over a particular period of time. Activity-specific energy cost values, expressed in metabolic equivalents (METS) or kilocalories, are then commonly used to estimate the total energy expenditure from all activities and/or categories of activities.The validation of LTPA questionnaires has had to rely upon indirect methods, such as the assessment of cardiorespiratory fitness, body composition and activity diaries. The reporting of the reliability of questionnaires has frequently been ignored, although in cases where it has been reported, doubt exists as to whether the consistency of the questionnaire or the consistency of subjects’ physical activity habits were being examined.LTPA questionnaires first appeared in the literature in the mid-1960s for use among specific, mainly middle-aged male population groups. Though they varied in their modes of scoring, periods of activity recall, and overall complexity, associations were universally observed between physical activity levels and chronic health conditions. However, it became apparent that different questionnaires did not yield the same results.In 1978, a questionnaire to assess only LTPA, the Minnesota LTPA Questionnaire, was published and despite its substantial limitations, has since established itself as the most popular option available. In recent years, shorter and simpler alternatives have been advocated, though most have yet to be adequately scrutinised. Associations have been found between LTPA and fitness levels, prompting the use of LTPA questionnaires in large-scale fitness surveys of both adults and children. Although LTPA has continued to be estimated in terms of energy expenditure, little attempt has been made to extend existing knowledge on the energy cost of physical activities. Existing values do not accommodate for individual intensities and inter-population activity variations. Consequently, standardised questionnaires are not yet viable.There exists considerable scope for further work with LTPA questionnaires, especially since the association between cornary heart disease and physical activity is now well recognised. Efforts ought to be directed at wider social groups for whom leisure-time activity may have distinct implications.

Semi-automated time-motion analysis of senior elite rugby league

The aim of this study was to examine the movement demands of senior elite rugby league with consideration of the impact of player position and match phase. A semi-automated match analysis image recognition system (ProZone 3, ProZone®, Leeds, England) was used to track 78 players during three senior elite matches. Players were categorised as outside backs (n = 30), pivots (n = 18), props (n = 12) or back row (n = 18). Total Distance (TD) covered, work-to-rest ratio (WRR) and % total time (%TT) spent in each of seven selected locomotive categories were determined for defending, attacking, ball in play and ball out of play phases. Analysis revealed that during the 86.8 min of match time, the mean TD covered was 8,503 ± 631 m, with pivots (8,800 ± 581 m) and outside backs (8,142 ± 630 m) covering the most and least distances, respectively. For pivots, props and back row players, defending resulted in a significantly lower WRR than when attacking (P < 0.05). Outside backs had significantly higher WRRs for ball in play and defending than all other positional groups (P < 0.05). The time-motion data presented in this study provides position-specific benchmarks for assessing match performance.

HEART RATE RESPONSES TO SMALL-SIDED GAMES AMONG ELITE JUNIOR RUGBY LEAGUE PLAYERS

Foster, CD, Twist, C, Lamb, KL, and Nicholas, CW. Heart rate responses to small-sided games among elite junior rugby league players. J Strength Cond Res 24(4): 906-911, 2010-This study investigated the influences of player number and playing area size on the heart rate (HR) responses elicited by junior male rugby league players during small-sided games (SSGs). Twenty-two players from a professional club (n = 22, mean age: 14.5 ± 1.5 years; stature: 172.5 ± 11.4 cm; body mass: 67.8 ± 15.1 kg; &OV0312;o2peak: 53.3 ± 5.6 mL·kg−1·min−1; HRmax: 198 ± 7.8 beats·min−1) participated in 2 repeated trials of six 4-minute conditioned SSGs over a 2-week period. The SSGs varied by playing area size-15 × 25 m, 20 × 30 m, and 25 × 35 m-and player number-4v4 and 6v6. HRs were recorded continuously in each game and expressed as overall and age-related (15-16 and 12-13 years) means and percent of maximum (%HRmax). Analysis revealed nonsignificant (p > 0.05) effects of trials and playing area size on HRs but a significant effect of player number in the 15-16 age group only (p < 0.001), with HRs being higher in the 4v4 (90.6% HRmax) than the 6v6 SSGs (86.2% HRmax). The HR responses were found to be repeatable in all SSG conditions (within ± 1.9% HRmax), apart from the small 6v6 condition in the older players. The findings demonstrate that these SSGs generate physiological responses suitable for aerobic conditioning that, although unaffected by the size of the area used, are sensitive to the player number. Accordingly, among such players it is advisable that coaches use 4v4 SSGs to achieve an appropriate and consistent aerobic conditioning stimulus.

Statistical analyses in the physiology of exercise and kinanthropometry

Research into the physiology of exercise and kinanthropometry is intended to improve our understanding of how the body responds and adapts to exercise. If such studies are to be meaningful, they have to be well designed and analysed. Advances in personal computing have made available statistical analyses that were previously the preserve of elaborate mainframe systems and have increased opportunities for investigation. However, the ease with which analyses can be performed can mask underlying philosophical and epistemological shortcomings. The aim of this review is to examine the use of four techniques that are especially relevant to physiological studies: (1) bivariate correlation and linear and non-linear regression, (2) multiple regression, (3) repeated-measures analysis of variance and (4) multi-level modelling. The importance of adhering to underlying statistical assumptions is emphasized and ways to accommodate violations of these assumptions are identified.

Correlates of Self-Perceived Fitness

This paper reports the associations between two global measures of self-perceived fitness and numerous objective fitness and fitness-related measures among 118 British men and women (mean age = 37.9 yr.). Self-perceived fitness, indicated on both a semantic scale of excellent through very poor (I) and an ordinal scale of 1 through 5 (II), was significantly correlated with most fitness and fitness-related variables. For self-perceived fitness I and II, respectively, these included physical work capacity (rho = 0.48 and 0.51), percent body fat (rho = −0.27 and −0.39), grip strength (rho = 0.30 and 0.35), very hard leisure-time physical activity (rho = 0.47 and 0.35), and frequency of sweating (rho = 0.54 and 0.45). Stepwise regression analyses yielded Rs of 0.70 and 0.64 for self-perceived fitness I and II, respectively. A significant correlate of self-perceived fitness was self-perceived health (rho = 0.47), suggesting that people may perceive fitness and health in the same manner. The present data suggest the considerable scope for examining further how people interpret the concept of fitness.

Effort Perception in Children

SummaryStudies addressing children’s perceptions of exercise effort have appeared steadily in the scientific literature over the last 20 years, though they have been relatively sparse in number. With little or no regard for their suitability, researchers initially applied to children the methods and applications of the rating of perceived exertion (RPE) notion established amongst adults. Whilst some success was claimed, findings were inconclusive, possibly because of the use of an inappropriate measurement scale. More recently, the development of the child-specific Children’s Effort Rating Table (CERT) has advanced research in this domain and helped to focus attention on the numerous problems of applying this psychophysical concept to such immature subjects. Accordingly, the scope for further research in this discipline is now far broader than ever before.

Young people's participation in National Curriculum Physical Education: A study of 15—16 year olds in North-West England and North-East Wales

Drawing on data from a broader study which investigated the place of spor t and physical activity in the lives of 15—16 year olds in England and Wales, this paper examines a relatively neglected dimension of research in physical education, namely, young peoples par ticipation in spor t and physical activity through National Curriculum Physical Education (NCPE). The paper repor ts upon data generated by questionnaires completed by 1010 15—16 year olds who attended six secondar y schools in the Nor th-West of England and one secondar y school in the Nor th-East of Wales during 2003 and 2004. The study revealed strong inter-school variations in the mixes of spor ts that pupils experienced within NCPE. More specifically, the findings revealed that NCPE was largely dominated by competitive team-based spor ts that tend to be gender-stereotyped, alongside more individualized and less-competitive physical activities. It was also clear, however, that the repor ted levels and forms of participation in different spor ts and physical activities in NCPE during Years 10 and 11 varied significantly and differentially according to gender, social class, the school which young people attended, specialist spor ts college status and whether youngsters studied GCSE PE. The paper concludes by suggesting that inter-school variations are probably explainable in terms of a combination of traditions, facilities and the enthusiasms and perceptions of PE teachers.