排序方式： 共有58条查询结果，搜索用时 31 毫秒
1.
2.
3.
4.
Abstract The purpose of this study was to assess the agreement between two mobile cycle ergometer systems for recording high-intensity, intermittent power output. Twelve trained male cyclists (age 31.4 ± 9.8 years) performed a single 3 min intermittent cycle test consisting of 12 all-out efforts, separated by periods of passive recovery ranging from 5 to 15 s. Power output was recorded using a Polar S710 heart rate monitor and power sensor kit and an SRM Powercrank system for each test. The SRM used torque and angular velocity to calculate power, while the S710 used chain speed and vibration to calculate power. Significant differences (P < 0.05) in power were found at 8 of the 12 efforts. A significant difference (P = 0.001) was also found when power was averaged over all 12 intervals. Mean power was 556 ± 102 W and 446 ± 61 W for the SRM and S710 respectively. The S710 underestimated power by an average of 23% with random errors of ?/÷ 24% when compared with the SRM. Random errors ranged from 36% to 141% with a median of 51%. The results indicate there was little agreement between the two systems and that the Polar S710 did not provide a valid measure of power during intermittent cycling activity when compared with the SRM. Power recorded by the S710 system was influenced greatly by chain vibration and sampling rates. 相似文献
5.
6.
7.
The purpose of this study was to assess the power output of field-based downhill mountain biking. Seventeen trained male downhill cyclists (age 27.1 +/- 5.1 years) competing nationally performed two timed runs of a measured downhill course. An SRM powermeter was used to simultaneously record power, cadence, and speed. Values were sampled at 1-s intervals. Heart rates were recorded at 5-s intervals using a Polar S710 heart rate monitor. Peak and mean power output were 834 +/- 129 W and 75 +/- 26 W respectively. Mean power accounted for only 9% of peak values. Paradoxically, mean heart rate was 168 +/- 9 beats x min(-1) (89% of age-predicted maximum heart rate). Mean cadence (27 +/- 5 rev x min(-1)) was significantly related to speed (r = 0.51; P < 0.01). Analysis revealed an average of 38 pedal actions per run, with average pedalling periods of 5 s. Power and cadence were not significantly related to run time or any other variable. Our results support the intermittent nature of downhill mountain biking. The poor relationships between power and run time and between cadence and run time suggest they are not essential pre-requisites to downhill mountain biking performance and indicate the importance of riding dynamics to overall performance. 相似文献
8.
Liz Atkins 《British Journal of Special Education》2016,43(1):6-21
This article explores tensions between the policies and practice of inclusion and the lived experiences of disabled young people in education. Drawing on the narratives of two young men who participated in a small pilot study, it utilises theoretical concepts related to disability, structure and agency, and power and control, as it explores the ways in which inclusion can create subtle (and sometimes not so subtle) forms of exclusion. Focusing on the young men's experiences of further and higher education, it is argued that inclusive practices and policies, however well intentioned, can create new and subtle forms of marginalisation through the structures and discourse intended to address exclusion. I conclude by questioning whether, in a diverse and disparate society, in which all our lives are defined by the extent to which we are more or less equal than others, inclusion can ever be anything other than an illusory concept. 相似文献
9.
10.
Atkins PJ 《Endeavour》2011,35(2-3):74-79
This article argues for material histories of food. In recent decades food historians have tended to emphasize the cultural factors in consumption, in addition to the already well-established social, political and economic perspectives, but what is still missing is the stuff in foodstuffs. With reference in particular to milk and wine, the suggestion here is that physical and chemical composition is a major influence in what we might call the biographies of particular items of food and drink. Product characteristics are rarely static for long and today's mass-produced bread is different from that of the past, but then so are the flour, the yeast, and the even the butter that is spread on it. Adulteration was a particularly interesting aspect of composition in the nineteenth century and was the key to the emergence of two different traditions of understanding and valuing food quality. 相似文献