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James D. George Danielle I. Bradshaw Annette Hyde Pat R. Vehrs Ronald L. Hager Frank G. Yanowitz 《Measurement in physical education and exercise science》2013,17(3):149-160
The purpose of this study was to develop an age-generalized regression model to predict maximal oxygen uptake (VO2max) based on a maximal treadmill graded exercise test (GXT; George, 1996). Participants (N?=?100), ages 18–65 years, reached a maximal level of exertion (mean?±?standard deviation [SD]; maximal heart rate [HRmax]?=?185.2?±?12.4 beats per minute (bpm); maximal respiratory exchange ratio [RERmax]?=?1.18?±?0.05; maximal rating of perceived exertion (RPEmax)?=?19.1?±?0.7) during the GXT to assess VO2max (mean?±?SD; 40.24?±?9.11 mL·kg?1·min?1). Multiple linear regression generated the following prediction equation (R?=?.94, standard error of estimate [SEE]?=?3.18 mL·kg?1·min?1, %SEE?=?7.9): VO2max (mL·kg?1·min?1)?=?13.160?+?(3.314 × gender; females?=?0, males?=?1) ? (.131 × age) ? (.334 × body mass index (BMI))?+?(5.177 × treadmill speed; mph)?+?(1.315 × treadmill grade; %). Cross validation using predicted residual sum of squares (PRESS) statistics revealed minimal shrinkage (Rp ?=?.93 and SEE p ?=?3.40 mL·kg?1·min?1); consequently, this model should provide acceptable accuracy when it is applied to independent samples of comparable adults. Standardized β-weights indicate that treadmill speed (.583) was the most effective at predicting VO2max followed by treadmill grade (.356), age (?.197), gender (.183), and BMI (?.148). This study provides a relatively accurate regression model to predict VO2max in relatively fit men and women, ages 18–65 years, based on maximal exercise (treadmill speed and grade), biometric (BMI), and demographic (age and gender) data. 相似文献
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Research progress of transparent conducting ZnO:Al(ZAO)films 总被引：1，自引：0，他引：1
Owing to both of its high carrier concentration and large band gap,ZnO:Al(ZAO)films which is an n-type degenerate semiconductor,exhibits low resistance and high transmittance in the visible range.This work studies the crystal structure,optical and electrical properties and preparation methods of ZAO films,and discusses the existing problems and application prospective of ZAO films. 相似文献
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The aim of this study was to develop an exercise protocol to simulate tennis matchplay on a 'category 2' surface. Match analyses were used to form the basis for the design of the protocol. The protocol involved playing against a tennis ball serving machine. Part A of the protocol comprised 92 min 46 s of simulated tennis matchplay; Part B consisted of continuous hitting to the point of 'volitional fatigue' or when the required hitting frequency for two consecutive ball feeds could no longer be maintained. Ten elite tennis players (5 males, 5 females) volunteered to participate in the study, which was performed on an indoor tennis court (Matchplay?, En-Tout-Cas)?. Their age, body mass and estimated maximal oxygen uptake were as follows: males, 21.7±1.0 years, 73.6±2.6 kg and 58.0±1.7 ml?·?kg?1?·?min?1, respectively; females, 21.9±1.3 years, 62.3±2.0 kg and 42.2±0.7 ml?·?kg?·?min?1, respectively (mean±). Heart rate, change in body mass and time to volitional fatigue were monitored. The heart rate responses of the participants to the simulated matchplay (range: 140-157 beats?·?min?1, 73-81% peak heart rate) were consistent with the results of previous studies, for 'actual' matchplay. This protocol was successful in simulating similar physiological responses in Part A to 'actual' matchplay on a 'category 2' surface, in a controlled environment; it was also a sensitive evaluation tool of skilled performance in Part B. The current protocol may be used as a baseline protocol for studying the influence of, for example, training and dietary intervention on performance. 相似文献
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David E. Nielson Pat R. Vehrs Ron L. Hager Carrie V. Webb 《Measurement in physical education and exercise science》2013,17(4):252-264
The purpose of this study was to develop a multiple linear regression model to predict treadmill VO2max scores using both exercise and non-exercise data. One hundred five college-aged participants (53 male, 52 female) successfully completed a submaximal cycle ergometer test and a maximal graded exercise test on a motorized treadmill. The submaximal cycle protocol required participants to achieve a steady-state heart rate equal to at least 70% of age-predicted maximum heart rate (220-age), while the maximal treadmill graded exercise test required participants to exercise to volitional fatigue. Relevant submaximal cycle ergometer test data included a mean (±SD) ending steady-state heart rate and ending workrate equal to 164.2 ± 13.0 bpm and 115.3 ± 27.0 watts, respectively. Relevant non-exercise data included a mean (±SD) body mass (kg), perceived functional ability score, and physical activity rating score of 74.2 ± 15.1, 15.7 ± 4.3, and 4.7 ± 2.1, respectively. Multiple linear regression was used to generate the following prediction of (R = .91, standard error of estimates (SEE) = 3.36 ml·kg?1·min?1): VO2max = 54.513 + 9.752 (gender, 1 = male, 0 = female) – .297 (body mass, kg) + .739 (perceived functional ability, 2–26) + .077 (work rate, watts) – .072 (steady-state heart rate). Each predictor variable was statistically significant (p < .05) with beta weights for gender, body mass, perceived functional ability, exercise workrate, and steady-state heart rate equal to .594, –.544, .388, .305, and –.116, respectively. The predicted residual sums of squares (PRESS) statistics reflected minimal shrinkage (RPRESS = .90, SEEPRESS = 3.56 ml·kg?1·min?1) for the multiple linear regression model. In summary, the submaximal cycle ergometer protocol and accompanying prediction model yield relatively accurate VO2max estimates in healthy college-aged participants using both exercise and non-exercise data. 相似文献
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Danielle I. Bradshaw James D. George Annette Hyde Michael J. LaMonte Pat R. Vehrs Ronald L. Hager 《Research quarterly for exercise and sport》2013,84(4):426-433
Abstract The purpose of this study was to develop a regression equation to predict maximal oxygen uptake (VO2max) based on nonexercise (N-EX) data. All participants (N= 100), ages 18–65 years, successfully completed a maximal graded exercise test (GXT) to assess VO2max (M= 39.96 mL·kg -1· min -1 , SD = 9.54). The N-EX data collected just before the maximal GXT included the participant's age; gender; body mass index (BMI); perceived functional ability (PFA) to walk, jog, or run given distances; and current physical activity (PA-R) level. Multiple linear regression generated the following N-EX prediction equation (R = .93, SEE = 3.45 mL·kg -1· min -1 , %SEE= 8.62): VO2max (mL·kg -1· min -1 ) = 48.0730 + (6.1779 x gender; women = 0, men = 1) – (0.2463 x age) – (0.6186 x BMI) + (0.7115 x PFA) + (0.6709 x PA-R). Cross validation using PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage (R p = .91 and SEE p = 3.63 mL·kg -1· min -1 ); thus, this model should yield acceptable accuracy when applied to an independent sample of adults (ages 18–-65 years) with a similar cardiorespiratory fitness level. Based on standardized β-weights, the PFA variable (0.41) was the most effective at predicting VO2max followed by age (-0.34), gender (0.33), BMI (-0.27), and PA-R (0.16). This study provides a N-EX regression model that yields relatively accurate results and is a convenient way to predict VO2max in adult men and women. 相似文献
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伟大的科学家Einstein曾说他感觉到自然界有统一性,他说“这是一种壮丽的感觉”,他首先提倡研究四种作用力的统一场论,提出过“黎曼空间几何统一场论”[1,2],未能成功。后来也有人提出“量子统一场论”[3],“规范统一场论”[4],“弱-电统一场论”[5,6,7],“三种力统一场论”[8] 相似文献
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Camille Thomas Gilbert Fellingham Pat Vehrs 《Measurement in physical education and exercise science》2013,17(2):108-121
The purposes of this study were to develop a notational system to evaluate passing, dribbling, first touch, and individual defensive skills as they relate to success during women's soccer games and to develop a statistical model to weigh the importance of each skill on creating scoring opportunities. Sequences of skills in ten games of a National Collegiate Athletic Association Division I intercollegiate women's soccer team were coded using well defined performance scores and outcomes. The notational analysis system was highly reliable as demonstrated by Spearman's rank correlations (>.98) between the first and second notation of three games for all four skills. The importance scores calculated from a Bayesian model demonstrated that dribbling (.0127) was the most important skill on creating scoring opportunities, followed by first touch (.0079), passing (.0075), and individual defense (.0050). The notational system developed from this study provides coaches with reliable and objective information to improve practice planning and optimize performance. 相似文献
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具有重要史料价值的《战国策》,因大量纵横游说之辞中对夸饰与虚构手法的运用而富有浓厚的学色彩,其夸饰与虚构的体现形式多种多样。《战国策》的学成就,在先秦史传学中,许多方面具有独创性,对后世学的发展产生过深元的影响。 相似文献
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Bradshaw DI George JD Hyde A LaMonte MJ Vehrs PR Hager RL Yanowitz FG 《Research quarterly for exercise and sport》2005,76(4):426-432
The purpose of this study was to develop a regression equation to predict maximal oxygen uptake (VO2max) based on nonexercise (N-EX) data. All participants (N = 100), ages 18-65 years, successfully completed a maximal graded exercise test (GXT) to assess VO2max (M = 39.96 mL x kg(-1) x min(-1), SD = 9.54). The N-EX data collected just before the maximal GXT included the participant's age; gender; body mass index (BMI); perceived functional ability (PFA) to walk, jog, or run given distances; and current physical activity (PA-R) level. Multiple linear regression generated the following N-EX prediction equation (R = .93, SEE = 3.45 mL x kg(-1) x min(-1), % SEE = 8.62): VO2max (mL x kg(-1) x min(-1)) = 48.0730 + (6.1779 x gender; women = 0, men = 1) - (0. 2463 x age) - (0.6186 x BMI) + (0.7115 x PFA) + (0.6709 x PA-R). Cross validation using PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage (R(p) = .91 and SEE(p) = 3.63 mL x kg(-1) x min(-1)); thus, this model should yield acceptable accuracy when applied to an independent sample of adults (ages 18-65 years) with a similar cardiorespiratory fitness level. Based on standardized beta-weights, the PFA variable (0.41) was the most effective at predicting VO2max followed by age (-0.34), gender (0.33), BMI (-0.27), and PA-R (0.16). This study provides a N-EX regression model that yields relatively accurate results and is a convenient way to predict VO2max in adult men and women. 相似文献
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Pat R. Vehrs James D. George Gilbert W. Fellingham Sharon A. Plowman Kymberli Dustman-Allen 《Measurement in physical education and exercise science》2013,17(2):61-72
This study was designed to develop a single-stage submaximal treadmill jogging (TMJ) test to predict VO2max in fit adults. Participants (N?=?400; men?=?250 and women?=?150), ages 18 to 40 years, successfully completed a maximal graded exercise test (GXT) at 1 of 3 laboratories to determine VO2max. The TMJ test was completed during the first 2 stages of the GXT. Following 3 min of walking (Stage 1), participants achieved a steady-state heart rate (HR) while exercising at a comfortable self-selected submaximal jogging speed at level grade (Stage 2). Gender, age, body mass, steady-state HR, and jogging speed (mph) were included as independent variables in the following multiple linear regression model to predict VO2max (R?=?0.91, standard error of estimate [SEE]?=?2.52 mL?·?kg?1?·?min?1): VO2max (mL?·?kg?1?·?min?1)?=?58.687?+?(7.520 × Gender; 0?=?woman and 1?=?man)?+?(4.334 × mph) ? (0.211 × kg) ? (0.148 × HR) ? (0.107 × Age). Based on the predicted residual sum of squares (PRESS) statistics (RPRESS?=?0.91, SEE PRESS?=?2.54 mL?·?kg?1?·?min?1) and small total error (TE; 2.50 mL?·?kg?1?·?min?1; 5.3% of VO2max) and constant error (CE; ?0.008 mL?·?kg?1?·?min?1) terms, this new prediction equation displays minimal shrinkage. It should also demonstrate similar accuracy when it is applied to other samples that include participants of comparable age, body mass, and aerobic fitness level. This simple TMJ test and its corresponding regression model provides a relatively safe, convenient, and accurate way to predict VO2max in fit adults, ages 18 to 40 years. 相似文献
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