Reliability of power output measurements during repeated treadmill sprinting in rugby players

The non-motorized treadmill system initially reported by Lakomy in 1984 has been used extensively to assess sprinting performance. However, there has been limited research into the reliability of power output measurement using such systems. The aim of this study was to design a system and protocol capable of measuring treadmill sprinting performance in rugby players and to assess the reliability of this system for measuring power output. Twenty-seven rugby players, all of whom were familiar with treadmill sprinting, performed three maximal 6 s sprints with 2 min recovery between sprints, on two occasions 1 week apart. Both tests were performed on a non-motorized Woodway tramp treadmill, interfaced to a data acquisition system. There were no significant differences (P > 0.05) between power output for repeated trials on the same day (between trials) or for repeated trials on different days (between days). Limits of agreement for maximum average power (the average of 100 readings per second) were 4+/-98 and 30+/-157 W for between trials and between days, respectively. When reported as ratio limits of agreement, these were 1.07 (*/divided 1.12) and 1.03 (*/divided 1.16), respectively. The limits of agreement for maximum instantaneous power (the highest of 100 readings per second) were 51+/-464 and 105+/-588 W for between trials and between days, respectively. When reported as ratio limits of agreement, these were 1.02 (*/divided 1.20) and 1.04 (*/divided 1.21) for between trials and between days, respectively. The coefficients of variation for all measures of power output were less than 9.3%. Hence, the treadmill system and protocol developed in this study provide a reliable measure of power output for rugby players.     

Development of a boxing dynamometer and its punch force discrimination efficacy

The development of sport-specific dynamometers is an important step towards ecological validity in analysing athlete performance. Design limitations in previous punch-measuring devices have resulted in values which may not or cannot fully reflect the force and multidirectional components in a punch. In developing this boxing dynamometer, a triaxial force measurement system and a boxing manikin interface were combined. The repeatability and accuracy of the dynamomoter were assessed using simulated straight punches. Discrimination efficacy was assessed by comparison of the maximal punching force of seven elite, eight intermediate and eight novice boxers during simulated boxing, throwing straight punches. For the elite, intermediate and novice groups, respectively, the maximal straight punching forces (mean +/- s(mean)) were 4800 +/- 227 N, 3722 +/- 133 N and 2381 +/- 116 N for the rear hand, and 2847 +/- 225 N, 2283 +/- 126 N and 1604 +/- 97 N for the lead hand. For all groups, maximal forces were larger for the rear than the lead hand (P < 0.001). Maximal punching force was greater in the elite than the intermediate group, and greater in the intermediate than the novice group (P < 0.05). The boxing dynamometer discriminated effectively between punching performance at three standards of performance and between the punching force of the rear and lead hands.     

Fathers online: learning about fatherhood through the internet

In the transition to fatherhood, men face numerous challenges. Opportunities to learn new practices and gain support are limited, although the provisions of father-specific spaces such as fathers' antenatal classes or "responsible fathering" programs are important advances. This article explores how men use the social space of a father-specific Internet chat room to learn about fathering. Messages to an Australian-hosted, father-specific chat room (for fathers of infants or young children) were examined, and three overlapping themes illustrated men's perceptions of their transition to fatherhood. The themes concerned recognition of and response to a lack of social space, services, and support for new fathers. The implications for fathers' perinatal education are discussed.     

中国民族声乐艺术风格的演变和发展

中国民族声乐艺术从20世纪30-40年代的成熟，到21世纪的多元发展，在社会公众审美活动及中国化发展格局中的地位愈加彰显．在这种情势下，对中国民族声乐艺术几十年来风格的演变和发展进行分析与反思，从中引发带有规律性的历史经验和艺术经验，无疑对今后中国民族声乐艺术向前推进将产生积极影响。