Participation-related relative age effects in Masters swimming: a 6-year retrospective longitudinal analysis

Medic and colleagues (Medic, Starkes, & Young, 2007) found that relatively younger cohorts of Masters athletes had higher participation rates and achieved higher performances compared with a relatively older cohort. Considering that Medic and colleagues' (2007) study was cross-sectional in nature, the purpose of this investigation was to employ a retrospective longitudinal study design to examine the participation rates of Masters swimmers as a function of an individual's constituent year within any 5-year age category over a period of 6 years. Using archived data from the 2003 to 2009 US Masters Short Course National Championships, swimmers' attendance was followed for a period of six consecutive years. Results indicated that a participation-related relative age effect was observed among swimmers who, over a period of 6 years, competed in either at least one championship (N = 2596; Cochran's Q? = 64.16, r(s) = -0.92, both P < 0.0001) or at least three championships (N = 441; Cochran's Q? = 47.51, r(s) = -0.91, both P < 0.0001). Overall, effect size analyses indicated that the odds of a Masters swimmer participating in the championship during the first constituent year of any 5-year age category was more than two times greater than the odds of that athlete participating during the fifth constituent year.     

VO2 prediction and cardiorespiratory responses during underwater treadmill exercise

We compared cardiorespiratory responses to exercise on an underwater treadmill (UTM) and land treadmill (LTM) and derived an equation to estimate oxygen consumption (VO2) during UTM exercise. Fifty-five men and women completed one LTM and five UTM exercise sessions on separate days. The UTM sessions consisted of chest-deep immersion, with 0, 25, 50, 75, and 100% water-jet resistance. All session treadmill velocities increased every 3 min from 53.6 to 187.8 m x min(-1). Cardiorespiratory responses were similar between LTM and UTM when jet resistance for UTM was 50%. Using multiple regression analysis, weight-relative VO2 could be estimated as: VO2 (mLO2 c kg(-1) x min(-1)) = 0.19248 x height (cm) + 0.17422 x jet resistance (% max) + 0.14092 x velocity (m x min(-1)) -0.12794 x weight (kg)-27.82849, R2 = .82. Our data indicate that similar LTM and UTM cardiorespiratory responses are achievable, and we provide a reasonable estimate of UTM VO2.     

The secular trend for grip strength in Canada and the United States

Worldwide, body weight has risen dramatically in recent decades, raising the question of whether there were concomitant changes in physical fitness. Past research with children and adolescents has shown that body weight and grip strength are positively correlated. Therefore, it was predicted that grip strength had increased on average in children and adolescents over the past four or five decades. To test this prediction, relevant data were extracted from 18 studies for males (N = 5676 in total) and 17 studies for females (N = 5489 in total). The studies were conducted in Canada and the United States from about 1966 on, with participants' ages ranging from 6 through 19 years. Weighted least squares regression analyses showed that grip strength was significantly predicted by age but not by country. Male grip strength decreased significantly over the period covered, but the change was very small, accounting for far less than 1% of the variance in male grip strength. Discussion focuses on potential explanations for why grip strength did not change over time as predicted.     

Effect of different swim caps on the assessment of body volume and percentage body fat by air displacement plethysmography

Isothermal air trapped in scalp hair generates an underestimation of body volume when it is measured by air displacement plethysmography. The aim of this study was to examine the effect of wearing different types of swim caps on the measurement of body volume and percentage body fat by air displacement plethysmography. It was hypothesized that wearing a silicone swim cap would more thoroughly compress scalp hair compared with a lycra swim cap, yielding higher estimates of body volume and percent body fat. Thirty female participants aged 25.7 ± 6.4 years were measured in random order when wearing no swim cap, a lycra swim cap or a silicone swim cap. For the no-cap versus lycra cap condition, the mean bias for body volume was -0.579 ± 0.380 litre (limits of agreement: -1.340 to 0.181 litre) and for percent fat -4.9 ± 3.1% fat (limits of agreement: -11.2 to 1.3% fat) (P < 0.05). For the silicone versus lycra condition, the mean bias for body volume was 0.137 ± 0.099 litre (limits of agreement: -0.062 to 0.335 litre) and for percent fat 1.2 ± 0.9% fat (limits of agreement: -0.5 to 2.9% fat) (P < 0.05). In conclusion, attention should be paid to optimal compression of isothermal air trapped in scalp hair when using air displacement plethysmography. The present results suggest that this compression may be more thorough when wearing a silicone swim cap.     

The rating of perceived exertion predicts intermittent vertical jump demand and performance

The aims of this study were (a) to assess the ability of the rating of perceived exertion (RPE) to predict performance (i.e. number of vertical jumps performed to a fixed jump height) of an intermittent vertical jump exercise, and (b) to determine the ability of RPE to describe the physiological demand of such exercise. Eight healthy men performed intermittent vertical jumps with rest periods of 4, 5, and 6 s until fatigue. Heart rate and RPE were recorded every five jumps throughout the sessions. The number of vertical jumps performed was also recorded. Random coefficient growth curve analysis identified relationships between the number of vertical jumps and both RPE and heart rate for which there were similar slopes. In addition, there were no differences between individual slopes and the mean slope for either RPE or heart rate. Moreover, RPE and number of jumps were highly correlated throughout all sessions (r = 0.97-0.99; P < 0.001), as were RPE and heart rate (r = 0.93-0.97; P < 0.001). The findings suggest that RPE can both predict the performance of intermittent vertical jump exercise and describe the physiological demands of such exercise.     

Navigating implementation dilemmas in technology-forcing policies: A comparative analysis of accelerated smart meter diffusion in the Netherlands,UK, Norway,and Portugal (2000-2019)

This paper addresses the implementation of technology-forcing policies in open-ended diffusion processes that involve companies and regulators as well as consumers and civil society actors. Mobilising insights from the societal embedding of technology framework and policy steering theories, we investigate two implementation dilemmas that relate to an overarching tension between flexibility (to enable technological learning and stakeholder engagement) and coordinated push (to focus actors and drive deployment): a) early or late formulation of initial targets, and b) technocratic or emergent-adaptive implementation styles. We investigate these dilemmas with four comparative case studies of smart electricity meters between 2000 to 2019, which diffused rapidly in the Netherlands, Norway, and Portugal, but decelerated in the UK. We relate these differences to policy choices, and identify two patterns for successful implementation of technology-forcing policies: a) start with early targets and a technocratic style, but make adjustments if there are substantial protests or technical problems, and b) start with an emergent-adaptive style and formulate and enforce targets later, once technical and social stabilisation has occurred.     

School learning support for teacher technology integration from a self-determination theory perspective

Teacher technology integration research on persistence is needed. Teachers’ persistence is strongly associated with their autonomous motivation, as defined by self-determination theory (SDT); however, most SDT-based studies have focused on teachers’ support and students’ motivation and well-being. SDT founders also recently suggested that future studies should include teacher motivation towards the use of technology. Accordingly, this experimental and longitudinal study aimed to investigate how the proposed support encouraged and sustained the low- and high- quality teachers’ integration practices. It proposed a school learning support intervention with three dimensions—leader, expert, and peer support—to meet teachers’ basic needs and thereby increase their motivation for and persistence in classroom technology integration. It had a sequential explanatory mixed-methods design, involved 122 school teachers and lasted for 22 months. Pre-, post- and delay- questionnaires and two arounds of interviews were used to collect the teachers perceptions on needs satisfaction and technology integration practices. The results suggest that the support increased the extent to which the teachers’ needs were met, resulting in more high-quality (student-centered) but not low-quality (lecturing) integration practices. However, the intervention sustained both types of integration practices. The findings offer three major empirical implications, makes two theoretical contributions, and offers four practical suggestions for researchers and practitioners.