Neuromuscular,biochemical and perceptual post-match fatigue in professional rugby league forwards and backs

Abstract

In this study, we investigated changes in creatine kinase, perceptual and neuromuscular fatigue of professional rugby league players after match-play. Twenty-three male rugby league players (10 backs, 13 forwards) had their creatine kinase, perceptual ratings of fatigue, attitude to training, muscle soreness, and flight time in a countermovement jump measured before and 1 and 2 days after (day 1 and day 2 respectively) league matches. Total playing time, offensive and defensive contacts were also recorded for each player. Creatine kinase was higher both 1 and 2 days after than before matches (P < 0.05) in forwards and backs. Similarly, perceived fatigue and muscle soreness were higher than pre-match on both days 1 and 2 (P < 0.05), but did not differ between groups (P > 0.05). Jump performance was lower on day 1 but not day 2 for both groups (P < 0.05). While total playing time was longer in backs (P < 0.05), relative frequencies for all contacts were greater in forwards (P < 0.05). Contacts for forwards were correlated with all markers of fatigue (P < 0.05), but only flight time was correlated with offensive contacts in backs (P < 0.05). Despite the mechanisms of fatigue being different between forwards and backs, our results highlight the multidimensional nature of fatigue after a rugby league match and that these markers do not differ between positions.     

Comment on ‘Performance analysis in football: A critical review and implications for future research’

Abstract

MacKenzie and Cushion (2013) recently reviewed performance analysis research in association football (soccer). Their critical review focused on several themes related to methodological approaches such as sample size, match context and operational definitions and the implications of research findings to professional practice. In this response letter, we comment on additional pragmatic concerns regarding these key themes as well as some of the difficulties commonly faced when conducting performance analysis research.     

Developing Coincident Timing Skill in Children: A Comparison of Training Methods

Abstract

The present study attempted to determine whether the nature of training experiences influences the development of coincident timing skill in young children. The task involved visual tracking of a moving light sequence and a 43 cm arm movement to a padded target. Subjects attempted to tap the target coincident with the completion of the light sequence. Sixty first grade children were randomly assigned to one of five groups, with an equal number of males and females in each group. Subjects assigned to the training groups received 48 trials on each of two days, with stimulus speeds that were either slow (179 cm/sec or 4 mph), fast (313 cm/sec or 7 mph), varied-random (179, 224, 268, 313 cm/sec or 4, 5, 6, 7 mph), or varied-blocked (i.e., 6 consecutive trials with one speed before changing to another). Control subjects performed a neutral coloring activity during the training phase of the experiment. All subjects were then given 10 trials on a third day with each of two stimulus speeds not experienced previously; one slow (134 cm/sec or 3 mph) and one fast (358 cm/sec or 8 mph). During transfer trials all groups were more accurate with the fast than with the slow speed stimulus. Training method mattered most during slow speed transfer trials, with the most accurate performance demonstrated by the group receiving varied-blocked speeds during training. The least effective methods were fast speed training, especially for males, and varied-random speed training. It was concluded that training sessions for the development of coincident timing skill in young children should emphasize slower speed stimuli and blocking of additional speeds which are more rapid.     

Isokinetic Leg Flexion and Extension Strength of Elite Adolescent Female Track and Field Athletes

Abstract

Sixty-two elite adolescent (age: 16.39 ± 1.62 yrs) female track and field athletes volunteered to be measured isokinetically for peak torque of the leg flexors and extensors. The sample included 16 throwers, 11 jumpers, 12 middle-distance runners (> 400 m), and 23 sprinters. A Cybex II isokinetic dynamometer was used to measure dominant leg strength at 180°/sec. One-way ANOVA revealed significant between group differences for absolute flexion and extension (Nm), extension/body weight (Nm/Kg), and extension/lean body weight (Nm/Kg). Scheffe post-hoc comparisons showed that, for absolute leg extension strength, throwers were stronger than middle-distance runners (by 54.4%), sprinters (35.6%), and jumpers (23.6%). For absolute leg flexion movements, throwers were stronger than middle distance runners (37.4%) and sprinters (32.1%). Jumpers had greater extension peak torque values than middle-distance runners relative to body weight (14.0%), and throwers were stronger than middle-distance runners for extension/lean body weight (14.9%)). No other comparisons were significant. However, when strength was expressed relative to body weight or lean body weight, there were few differences between events for flexion or extension. Given that absolute strength scores were correlated with body weight and lean body weight, peak torque/body weight or peak torque/lean body weight may be more sensitive than absolute values as indicators of underlying factors (such as training status or fiber type composition) responsible for the differences in muscular strength between groups.     

The Variability of Practice Hypothesis: Further Tests and Methodological Discussion

Abstract

In the present study experimental subjects practiced variations in movement distance and/or movement time during training trials on a closed timing task. Control subjects trained with single distance-time combinations. During transfer trials all subjects attempted (without knowledge of results) a distance-time combination that was different (except in the case of one control condition) from any performed during training. The results revealed that the timing accuracy of the two experimental conditions that practiced a variety of times was significantly poorer than that of most of the other conditions during the training phase. However, transfer analyses revealed several significant differences between the performance of variable-trained and constant-trained conditions, in all cases favoring the former. It was concluded that the transfer benefits of variable practice are (a) not due to the particular movement component selected for variation during training, and (b) to some extent always determined by the similarity of training and transfer conditions experienced by constant-practice subjects.     

Yearly Changes in the Body Composition and Muscular Strength of High School Wrestlers

Abstract

The purpose of this investigation was to determine the yearly changes in body composition as well as absolute and relative isokinetic forearm flexion and extension strength of high school wrestlers. Evaluations of body composition (underwater weighing) were performed on 27 high school wrestlers prior to three consecutive seasons. In addition, isokinetic forearm flexion and extension strength values at 180°/s (Cybex II) were available for 20 of the subjects. The mean ages at the times of laboratory testing were 15.5 (± .5), 16.5 (± .5), and 17.5 (± .5) years. Repeated measures ANOVA or ANCOVA with Tukey post-hoc comparisons were used to locate significant (p<.05) differences across age for height, body weight, relative fat, body density, fat weight, fat-free weight, absolute muscular strength, and muscular strength covaried for body weight and fat-free weight. There were yearly increases in all variables except fat weight, forearm flexion covaried for fat-free weight and forearm extension covaried for fat-free weight. The results of this study indicated that the improved wrestling performance and the increase in weight classification which normally occurs during high school are, in part, a function of yearly changes in body composition and muscular strength.     

A Field Test of the Activity-Set Hypothesis for Warm-Up Decrement in an Open Skill

Abstract

To determine the relative effectiveness of different warm-up activities in eliminating postrest warm-up decrement (WUD), 65 highly skilled tennis players performed 60 forehand and 60 backhand groundstrokes, rested for either 5 or 15 min, engaged in one of five interpolated activities (additional rest, running in place, imagery, practice swings, or air dribbling), and then performed 12 additional forehands and backhands. An analysis of differences between prerest and postrest arousal measures (heart rate, positive cognitive arousal, and negative cognitive arousal) revealed that all of the interpolated activities except additional rest restored arousal to levels near those found at the end of prerest trials. Postrest WUD was also eliminated by practice swings and air dribbling and, to a slightly lesser extent, by running in place. We concluded that an effective warm-up for open skills such as the tennis groundstroke should include some form of overt physical activity that directs the attention of the performer to task-relevant cues.     

Fatigue Effects on the Timing Performance of Well-Practiced Subjects

Abstract

In an attempt to extend the laws of fatigue to the performance of highly practiced subjects, 24 college males were trained for four days (50 trials/day) on a coincident timing task prior to manipulation of the fatigue variable. On day 5, motor performance was immediately preceded by either local fatigue (static exercise), general fatigue (treadmill running), or no fatigue. Increased variable error was found for both local and general fatigue subjects as compared with controls on the first block of five trials following fatigue. However, by block 2 this difference had diminished. A constant error analysis on the first and second postfatigue trials revealed transitory overshooting of the criterion timing response for local fatigue subjects and undershooting for general fatigue subjects. The results suggested that local and general fatigue may alter the timing mechanism in different ways and that both are sources of at least transient decrements in the performance of well-practiced subjects.     

Why school-based narrative inquiry in physical education research? An international perspective

While conducting a comparative research study in secondary Physical Education in South Korea and the United States, the question arose as to why the narrative inquiry research method we employed was chosen to study the experiences of teachers teaching the particular subject area to youth enrolled in four secondary schools (middle and high) in South Korea and the United States. This article takes up the query by probing the roots of school-based narrative inquiry and the tight connections between our specific research method and the teacher-as-curriculum-maker image of teaching. Six qualities of narrative inquiry are elaborated through the use of narrative fragments excerpted from our Korea Research Foundation-sponsored study. These characteristics include: (1) justification for inquiry, (2) research in the midst, (3) research on the boundaries, (4) knowing through relationship, and (5) narrative truth, and (6) following where the story leads. Finally, the article returns to the intimate relationship between our chosen version of narrative inquiry and the teacher-as-curriculum-maker image and the kinds of contributions that the union of these robust orientations can make to the study of Physical Education in classroom settings.