Dietary supplements

For the athlete training hard, nutritional supplements are often seen as promoting adaptations to training, allowing more consistent and intensive training by promoting recovery between training sessions, reducing interruptions to training because of illness or injury, and enhancing competitive performance. Surveys show that the prevalence of supplement use is widespread among sportsmen and women, but the use of few of these products is supported by a sound research base and some may even be harmful to the athlete. Special sports foods, including energy bars and sports drinks, have a real role to play, and some protein supplements and meal replacements may also be useful in some circumstances. Where there is a demonstrated deficiency of an essential nutrient, an increased intake from food or from supplementation may help, but many athletes ignore the need for caution in supplement use and take supplements in doses that are not necessary or may even be harmful. Some supplements do offer the prospect of improved performance; these include creatine, caffeine, bicarbonate and, perhaps, a very few others. There is no evidence that prohormones such as androstenedione are effective in enhancing muscle mass or strength, and these prohormones may result in negative health consequences, as well as positive drug tests. Contamination of supplements that may cause an athlete to fail a doping test is widespread.     

Force-Time Curves of Voluntary Muscular Contraction at Varying Tensions

Abstract

A recording spring-loaded hand ergograph with fast moving paper was utilized to obtain a record of the entire hand contraction sequence. The subjects (N=40) were given a series of six contractions, each beginning at a different initial tension: 0, 10, 15, 20, 25, and 30 kilograms. The contractions were separated by one minute and the order was systematically rotated to minimize either learning or fatigue. The development of force was found to progress exponentially according to a three-component mathematical equation. The control group (zero pre-tension) achieved a greater maximal force (F=4.5) than all others, and was the only one with a clear advantage in speed and tension. The rate of change constants were comparable, but the early initial (negative) component disappeared at the 20 kilogram condition and beyond. The factor of rate seemed to be independent of tension level.     

Age-Related Differences in Muscular Strength and Muscular Endurance among Female Masters Swimmers

Abstract

The purpose of this study was to examine age-related differences in muscular strength and muscular endurance among 73 female masters swimmers aged 24 to 71 years. Each subject was assessed on measures of body size, grip strength, peak isokinetic torque of shoulder and knee flexion and extension, and endurance of shoulder and knee movements. Although swim training appears to have resulted in higher strength values for these swimmers than for less active women, an age-related decline in muscular strength values was nevertheless apparent. The results fail to reveal a similar age-related trend for muscular endurance, suggesting that swim training influences muscular endurance more than muscular strength among adult women.     

Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males

Abstract

Eighteen male subjects, ages 20–28 years, engaged in three fatigue bouts using an isokinetic dynamometer (Cybex II). Maximum knee extension contractions were given for 100 s at a rate of 30 per minute. The three contraction speeds chosen were 120° · s ^–1 160° · s ^–1 and 200° · s ^–1.Peak torque at 120° · s ^–1 was significantly greater (p <.05) than at 200° · s ^–1 for the first 60 s, and 160° · s ^–1 for the first 50 s. Thereafter, no significant differences existed among conditions. All three curves were found to follow two-component exponential functions as shown by the equation y_t =a ₂ e^k2^t – a ₁ e^k1^t + c. The three curves possessed similar rate constants for both components. Time to peak torque was achieved at similar times for testing at 160 and 200° · s ^–1 (p <.05). It is concluded that peak torque varies inversely with movement speed, and that the pattern of decrement is independent of movement speed. Time to peak torque does not appear to change significantly across trials in isokinetic fatigue.     

Characteristics of the start in women's World Cup skeleton

This study characterizes key elements of the start in elite female World Cup skeleton athletes. The top 20 female competitors in three World Cup races were videotaped within a calibrated space to allow the following components of the start to be quantified: (1) acceleration (velocity at 15-m mark, time to 15-m mark), (2) capacity (time to load, total number of steps to load), and (3) load (velocity at 45-m mark). A correlation analysis was used to establish the relationship between the variables of interest and overall start time (15- to 65-m mark). Velocity at the 15-m mark accounted for 86% of the variance in overall start time at St. Moritz and 85% at Sigulda. A stepwise regression analysis revealed that approximately 89% of the variation in start time could be explained by velocity at the 15-m mark, time to load, and velocity at the 45-m mark. Of the variables analysed in this study, rapid acceleration to attain a high velocity at the 15-m mark was the most important component of a fast overall start time. The importance of the time to load and velocity at the 45-m mark vary according to the different track characteristics.     

Heritability,Social Disadvantage and Psychosocial Intervention

To argue that anything as complex as human behaviour has multifactorial origins demanding a systems analysis is today almost a statement of the obvious. This does not, however, mean that a search for significant main effects in populations is unwarranted, provided that these can be shown in replicated studies across place and time. In this article two such effects will be examined. In both cases there is a massive amount of data available, much of it recent, and some of it based on sophisticated research designs.     

Education for girls in Ireland: secondary and vocational curricular provision 1930–1960

A challenge for historians of education is to explain the ways in which the development of education has been a gendered process. The literature tends to focus on primary and secondary schools; the role played by religious orders; the experiences of female teachers; ideological influences on curriculum; and the preparation of young girls for their role in society. Few historians, however, have examined vocational education and the impact of its ‘social efficiency’ orientation on girls. The literature that exists tends to treat both systems separately, and little effort has been made to compare the impact of both systems on girls’ opportunities within the society in which they lived. This omission in the literature is significant as such a comparison facilitates insights regarding state policies and priorities for the education of girls, the impact of social class, and national and local circumstances. This article compares both systems of education in Ireland and their impact on girls during the period 1930–1960.