Effect of Age,Sex, and Type of Feedback on Motor Performance and Locus of Control

The purpose of this study was to determine the effects of consistent positive and negative feedback on motor performance and a shift in locus of control. Comparisons of the data were made on the basis of age, sex, type of feedback, and internal–external (I–E) disposition. Extreme internal and external participants were offered positive or negative feedback on a rotary pursuit motor task over 20 trials, twice per week, for 6 weeks (a total of 240 trials). The results were as follows: (a) all eighth-grade (13-year-old) subjects displayed superior motor skill performance as compared to fifth-grade (10-year-old) students; (b) subjects across age groups who received positive feedback performed better than subjects given negative feedback; (c) a significant locus of control by feedback interaction indicated that high internals were superior to high externals under positive feedback conditions but that negative feedback produced inferior performance by internals compared to heightened performance by externals; (d) older subjects were more internal than younger subjects based on locus of control questionnaire data both prior to and immediately following the 6-week experiment; and (e) neither age group demonstrated a significant shift in locus of control in response to both the positive and negative feedback conditions.     

Carnosine and taurine contents in individual fibres of human vastus lateralis muscle

Analysis of ATPase characterized type I and type II fibres from biopsy samples of the vastus lateralis muscle of four male subjects showed a selective distribution of carnosine and free taurine similar to that observed in other species. The mean carnosine concentration was twice as high in type II compared with type I muscle fibres (23.2 +/- 17.8 and 10.5 +/- 7.6 mmol . kg -1 dry weight, respectively), while taurine was four times higher in type I compared with type II muscle fibres (39.2 +/- 17.8 and 9.6 +/- 2.6 mmol . kg -1 dw, respectively). Overlap in the concentration of carnosine or taurine between fibre types occurred only once in one subject. There was no overlap between fibre types in the ratio of carnosine to taurine. Higher carnosine concentrations in type II fibres will result in a greater contribution to the buffering of H+ arising from anaerobic metabolism. The contribution in a type II fibre with the highest carnosine content was estimated to equal 28% of that from other sources.     

The creatine content of Creatine Serum™ and the change in the plasma concentration with ingestion of a single dose

Three samples of Creatine Serum? ATP Advantage from Muscle Marketing USA, Inc. were assayed for creatine by two different techniques by four independent laboratories, and for creatinine by two different techniques by two laboratories. A further sample was assayed for phosphorylcreatine. Dry weight and total nitrogen were also analysed. Six male volunteers ingested in random order, over 3 weeks: (A) water; (B) 2.5?g creatine monohydrate (Cr?·?H₂O) in solution; and (C) 5?ml Creatine Serum? (reportedly containing an equivalent amount of Cr?·?H₂O). Blood samples were collected before and up to 8?h after each treatment and plasma was analysed for creatine and creatinine. Eight-hour urine samples were analysed for creatine. Ingestion of 2.5?g creatine monohydrate in solution resulted in a significant increase in plasma creatine (from 59.1±11.8?μmol?·?l^?1 to 245.3±74.6?μM μmol?·?l^?1; mean±s) and urinary creatine excretion. No increase in plasma or urinary creatine or creatinine was found on ingestion of Creatine Serum? or water. Analysis showed 5?ml of Creatine Serum? to contain <10?mg Cr?·?H₂O and approximately 90?mg creatinine. Phosphorylcreatine was not detectable and only a trace amount of phosphorous was present. Total nitrogen analysis ruled out significant amounts of other forms of creatine. We conclude that the trace amounts of creatine in the product would be too little to affect the muscle content even with multiple dosing.     

An investigation of the five-factor model of personality and coping behaviour in sport

Abstract

Coping strategies are important for performance in sport and individual differences may contribute to the coping strategies adopted by athletes. In this study, we explored the main and interactive effects of the big five personality dimensions on sport-related coping and compared personality profiles of discrete groups of athletes. Altogether, 253 athletes (mean age 21.1 years, s = 3.7) completed the NEO-FFI (Costa & McCrae, 1992 Costa, P. T. and McCrae, R. R. 1992. Revised NEO personality inventory and NEO five-factor inventory: Professional manual, Odessa, FL: Psychological Assessment Resources.  [Google Scholar]), and the Coping Function Questionnaire for Sport (Kowalski & Crocker, 2001 Kowalski, K. C. and Crocker, P. R. E. 2001. Development and validation of the Coping Function Questionnaire for adolescents in sport. Journal of Sport and Exercise Psychology, 23: 136–155. [Web of Science ®] , [Google Scholar]). Results showed that extraverted athletes, who were also emotionally stable and open to new experiences (a three-way interaction effect), reported a greater use of problem-focused coping strategies. Conscientious athletes (main effect), and athletes displaying high levels of extraversion, openness, and agreeableness (a three-way interaction effect), reported a greater use of emotion-focused coping strategies, and athletes with low levels of openness, or high levels of neuroticism (main effects), reported a greater use of avoidance coping strategies. Different personality characteristics were observed between higher-level and lower-level athletes, between men and women athletes, and between individual and team sport athletes. These findings suggest that the five-factor model of personality can help distinguish various levels of athletic involvement and can help identify the coping strategies athletes are likely to adopt during participation.     

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.     

Peak power output provides the most reliable measure of performance in prolonged intermittent-sprint cycling

Abstract

The aims of this study were to determine the reliability of an intermittent-sprint cycling protocol and to determine the efficacy of one practice session on main trials. Eleven men, moderately trained team-sport athletes, completed three visits to the laboratory involving a graded-exercise test and practice session and two trials of a Cycling Intermittent-Sprint Protocol separated by three days. Data for practice and main trials were analysed using typical error of measurement, intra-class correlation and least-products regression to determine reliability. Typical error of measurement (expressed as a coefficient of variation) and intra-class correlation for peak power output from all 20 sprints for trial 1 and trial 2 were 2.9 ± 12.8% (95% confidence interval: 2.0–5.0%) and 0.96 (95% confidence interval: 0.85–0.99), respectively. Typical errors of measurement and intra-class correlation for mean power output for all 20 sprints for trials 1 and 2 were 4.2 ± 11.9% (95% confidence interval: 2.9–7.4%) and 0.90 (95% confidence interval: 0.66–0.97), respectively. The results suggest that peak power output provides a more reliable measure than mean power output. The Cycling Intermittent-Sprint Protocol provides reliable measures of intermittent-sprint performance.     

Quantifying stroke coordination during the breathing action in front-crawl swimming using an instantaneous net drag force profile

Abstract

This study used both an instantaneous net drag force profile and a symmetry timing to evaluate the effect of the breathing action on stroke coordination. Twenty elite swimmers completed a total of six randomised front-crawl towing trials: (i) three breathing trials and (ii) three non-breathing trials. The net drag force was measured using an assisted towing device mounted upon a Kistler force platform, and this equipment towed the swimmer at a constant speed. The net drag force profile was used to create a stroke symmetry index for each swimming trial. Analysis using the symmetry indices identified that the majority of participants demonstrated an asymmetrical instantaneous net drag force stroke profile in both the breathing and non-breathing conditions, despite no significant differences in the time from finger-tip entry to finger-tip exit. Within the breathing condition, the faster swimmers compared to the slower swimmers demonstrated a lesser percentage of overlap between stroke phases on their breathing stroke side. During the non-breathing condition, the faster participants compared to the slower swimmers recorded a reduction in the percentage of overlap between stroke phases and less duration in the underwater stroke on their breathing stroke side. This study identified that the majority of participants demonstrated an asymmetrical net drag force profile within both conditions; however, asymmetry was less prevalent when examining with only the timing symmetry index.