Changes in selected cardiorespiratory responses to exercise and in body composition following a 12‐week aerobic dance programme

Cardiorespiratory and body composition changes were evaluated in 25 sedentary females, aged 18 to 30 years, following 12 weeks of aerobic dance training (3 days a week, 45 min a session). Fifteen subjects, from the same population, comprised a control group: they maintained their normal activity and dietary habits over the course of the study. Analysis of variance of the values for selected cardiorespiratory responses revealed that the aerobic dance programme produced training effects in the experimental group. These training effects were indicated by significant improvements in O₂ pulse, V _E, heart rate and perceived exertion during submaximal exercise. Significant improvements were also noted in VO₂ max, maximal O₂pulse, V _E max, maximal heart rate and maximal running time on the treadmill. Additionally, increases in lean body mass and body density, together with decreases in percentage body fat and the sum of four skinfold thicknesses were found to be significant for the experimental group. No significant improvements in any of these variables were found for the control group. It was concluded that this 12‐week aerobic dance programme was successful in promoting beneficial changes in cardiorespiratory fitness and body composition.     

Statistical methods for analysing discrete and categorical data recorded in performance analysis

In this paper, we identify appropriate statistical methods for analysing categorical differences in discrete variables or 'performance indicators' resulting from performance analysis. The random mechanisms associated with discrete events do not follow a normal distribution; that is, the normal distribution is a continuous not a discrete probability distribution. We propose appropriate statistical methods based on two key discrete probability distributions, the Poisson and binomial distributions. Two approaches are proposed and compared using examples from notational analysis. The first approach is based on the classic chi-square test of significance (both the goodness-of-fit test and the test of independence). The second approach adopts a more contemporary method based on log-linear and logit models fitted using the statistical software GLIM. Provided relatively simple one-way and two-way comparisons in categorical data are required, both of these approaches result in very similar conclusions. However, as soon as more complex models or higher-order comparisons are required, the approach based on log-linear and logit models is shown to be more effective. Indeed, when investigating those factors and categorical differences associated with binomial or binary response variables, such as the proportion of winners when attempting decisive shots in squash or the proportion of goals scored from all shots in association football, logit models become the only realistic method available. By applying log-linear and logit models to discrete events resulting from notational analysis, greater insight into the underlying mechanisms associated with sport performance can be achieved.     

The first joint BASES/BASEM Conference

The purpose of this study was to evaluate the dietary practices of soccer players of different ages. The diets of the members of four soccer teams (mean ages of 14.0, 15.0, 16.6 and 20.9 years, respectively) were examined. Our results show that the caloric intake per kilogram of body mass was significantly higher among the youngest players when compared with the adult players (P 相似文献   

Sports Mania: Essays on Fandom in the 21st Century

Abstract

Experimental studies have consistently reported higher peak power outputs at the termination of steeper ramp exercises. One explanation can be deduced from oxygen uptake kinetics. This short communication offers an alternative explanation based on the “critical power” concept of human bioenergetics. Algebraic, calculus, and geometric aspects of this explanation are all detailed, and it is illustrated with data from a previous study.     

Exercise intensity during wheelchair rugby training

Abstract

The purpose of this study was to determine the ability of individuals with a cervical spinal cord injury to achieve and sustain a cardiorespiratory training intensity during wheelchair rugby. Nine wheelchair rugby players completed a continuous peak exercise test on a SciFit Pro I arm ergometer with stage increases each minute to determine peak heart rate and power output. Approximately one week after peak exercise testing, heart rate was recorded (every 5 s) during three regularly scheduled rugby training sessions. Data were analysed to determine the number of continuous minutes that participants spent above 70% of heart rate reserve under various rugby training activities. The percent of time spent at or above 70% heart rate reserve varied across participants and conditions. Continuous pushing was the least variable training condition among participants with the sample averaging greater than 73% of time above the target heart rate. Scrimmage training was highly variable across participants with a range of 0% to 98% of time above the criterion. Results of this study indicate that wheelchair rugby training enables some participants to reach a training intensity associated with improved cardiorespiratory fitness, and that the type (or kind) of training activity dictates the extent to which individuals sustain such a threshold.     

Evolution and revolution: Gauging the impact of technological and technical innovation on Olympic performance

Abstract

A number of studies have pointed to a plateauing of athletic performance, with the suggestion that further improvements will need to be driven by revolutions in technology or technique. In the present study, we examine post-war men's Olympic performance in jumping events (pole vault, long jump, high jump, triple jump) to determine whether performance has indeed plateaued and to present techniques, derived from models of human growth, for assessing the impact of technological and technical innovation over time (logistic and double logistic models of growth). Significantly, two of the events involve well-documented changes in technology (pole material in pole vault) or technique (the Fosbury Flop in high jump), while the other two do not. We find that in all four cases, performance appears to have plateaued and that no further “general” improvement should be expected. In the case of high jump, the double logistic model provides a convenient method for modelling and quantifying a performance intervention (in this case the Fosbury Flop). However, some shortcomings are revealed for pole vault, where evolutionary post-war improvements and innovation (fibre glass poles) were concurrent, preventing their separate identification in the model. In all four events, it is argued that further general growth in performance will indeed need to rely predominantly on technological or technical innovation.     

The changing shape characteristics associated with success in world-class sprinters

Abstract

The aims of this study were to identify whether relative shape and size characteristics of world-class sprinters have changed over time, and whether any anthropometric parameters characterize the most successful world-class sprinters. The results suggest that body mass index, reflecting greater muscle mass rather than greater adiposity, is an important factor associated with success in both male and female world-class sprinters over time. However, in female athletes the reciprocal ponderal index (RPI) has emerged as a more important indicator of success over several decades, with taller, more linear sprinters achieving greater success, as measured by sprint speed. In male sprinters it is only in the most recent decade that RPI has emerged as an important predictor of success. We speculate that the prominence of the RPI and an ectomophic somatotype being typical of the most successful world-class sprinters might be explained, in part, by the influence of stride length on sprint speed. In conclusion, these results suggest that coaches, selectors, and sports scientists should consider body shape when selecting potential athletes for sprint events, encouraging more linear athletes with a high RPI.     

The influence of maturation,body size and physical self-perceptions on longitudinal changes in physical activity in adolescent girls

Abstract

The aim of this study was to adopt a longitudinal design to explore the direct effects of both absolute and relative maturation and changes in body size on physical activity, and explore if, and how, physical self-perceptions might mediate this effect. We recruited 208 girls (11.8 ± 0.4 years) at baseline. Data were collected at three subsequent time points, each 6 months apart. At 18 months, 119 girls remained in the study. At each time point, girls completed the Physical Activity Questionnaire for Children, the Pubertal Development Scale (from which, both a measure of relative and absolute maturation were defined) and the Physical Self-Perception Profile, and had physical size characteristics assessed. Multilevel modelling for physical activity indicated a significant negative effect of age, positive effect for physical condition and sport competence and positive association for relatively early maturers. Absolute maturation, body mass, waist circumference and sum of skinfolds did not significantly contribute to the model. Contrary to common hypotheses, relatively more mature girls may, in fact, be more active than their less mature peers. However, neither changes in absolute maturation nor physical size appear to directly influence changes in physical activity in adolescent girls.     

Effect of the Great Activity Programme on healthy lifestyle behaviours in 7–11 year olds

Abstract

The study investigated the effect of a school-based healthy lifestyles intervention on physical activity and dietary variables. In total 378 children (177 intervention, 201 control; age 9.75 ± 0.82 years (mean ± s)) took part in the 7-month intervention comprising: preparation for and participation in 3 highlight events (a dance festival, a walking event and a running event); an interactive website for pupils, teachers and parents; and vacation activity planners. Primary outcome measures were objectively measured physical activity (pedometers and accelerometers), endurance fitness and dietary variables. Multi-level modelling was employed for data analysis. The increase in physical activity was greater in the intervention group than the control group (steps: 1049 vs 632 daily steps each month; moderate to vigorous physical activity (MVPA) total: 4.6 min · day^?1 · month^?1 vs 1.3 min · day^?1 · month^?1; MVPA bouts: 5.4 min · day^?1 · month^?1 vs 2.6 min · day^?1 · month^?1; all P < 0.05). The increase in multi-stage fitness test distance was greater for intervention participants (46 vs 29 m · month^?1 of intervention, group × month interaction, P < 0.05). There were no differences between groups in dietary variables, body composition, knowledge of healthy lifestyles or psychological variables. Thus an intervention centred around highlight events and including relatively few additional resources can impact positively on the objectively measured physical activity of children.     

Rate of Force Development in the Handgripping Muscles by Females as a Function of Fatigue Level

Abstract

Twenty-eight young, adult women were tested for maximum voluntary contraction (MVC) of the grip flexors and were then given five fatigue trials in which the task was to maintain a maximum isometric contraction until the strength level had been degraded to either 80%, 60%, or 40% MVC. At that time, the subject relaxed and within one second was commanded to generate a single contraction as rapidly and forcefully as possible. Testing was also conducted in the nonfatigued state (1.00 MVC). Forces were determined at 4, 8, 16, 32, 64, 128, 256, 512, and 1,024 msec following the initial deflection of the pen from the baseline. Normalized force values were calculated by dividing the force expressed at the various time intervals by the maximum force generated under that condition at 1,024 msec. For both absolute and normalized rate of force development, the highest rate was attained between 32–64 msec. During that time period, the rate of absolute force development was reduced 10% at the 80% MVC level, 30% at 60% MVC, and 53% at 40% MVC. There was a definite pattern of depressed rate of absolute force development up to 256 msec at the higher fatigue levels. For normalized force, fatiguing a muscle to 80% MVC had no effect except at 64 msec where a greater percentage of maximal force was attained than at 1.00 MVC. Beyond that level of fatigue, however, normalized force tended to be adversely affected as fatigue progressed. The time required to develop either 50% or 70% of maximal force was significantly longer for the 40% MVC level than for the remaining conditions. In addition, the time necessary to develop 70% of maximal force was longer for the 60% MVC fatigue level than for the 80% MVC level.