Estimation of VO2max: a comparative analysis of five exercise tests

Thirty-eight female subjects (M +/ SD = 33 +/- 3.0 years) had VO2max measured on the cycle ergometer (M +/- SD = 37.3 +/- 6.4 ml.kg-1.min-1) and on the treadmill (M +/- SD = 41.3 +/- 6.6 ml.kg-1.min-1). VO2max was estimated for each subject from heart rate (HR) at submaximal workloads on the cycle ergometer using the Astrand-Rhyming nomogram (A/R) and the extrapolation method (XTP). VO2max was also estimated from three field tests: 1.5-mile run (RUN) (independent variable [IV] = time), mile walk (WALK) (IV = time, age, HR, gender, body weight), and the Queens College Step Test (ST) (IV = HR during 5-20 s recovery). Repeated measure ANOVA revealed significant mean differences between the criterion cycle ergometer VO2max versus A/R and XTP (20 and 12% overestimation). The WALK, RUN, and ST VO2max values were not significantly different from the criterion treadmill VO2max. The correlation between criterion VO2max estimated from the WALK and RUN were r = .73 (SEE = 4.57 ml,kg-1.min-1) and r = .79 (SEE = 4.13 ml.kg-1.min-1), respectively. The ST, A/R, and XTP had higher SEEs (13-13.5% of the mean) and lower r s (r = .55 to r = .66). These results suggest both the WALK and RUN tests are satisfactory predictors of VO2max in 30 to 39-year-old females.     

Transient VO2 Characteristics in Children at the Onset of Steady-Rate Exercise

Abstract

The transient oxygen uptake (VO₂) response during the initial phase of exercise was investigated in 28 children (mean age ± SD = 10.2 ± 2.28 years) during constant load submaximum bicycle ergometer exercise (mean power output ± SD = 56 ± 4.0 watts; mean VO₂ ± SD = .92 ± .141 [mdot] min^-1). The VO₂ half-time (VO₂ - t½) averaged (± SD) 34.8 (± 12.70) sec which is similar to that observed in adults. Examination of the VO₂-t ½ response as it related to age (7 to 14 years) showed that younger children attained steady-rate VO₂ more quickly than older children (r = .77 between age and VO₂-t½, P < .05). Body size, maturational level, exercise intensity, cardiorespiratory factors, and anaerobic potential are suggested as possible factors accounting for the positive age vs VO₂-t ½ relationship.     

Isokinetic Torque in Boys and Girls Ages 7 to 13: Effect of Age,Height, and Weight

The purpose of this study was to investigate torque differences between 28 boys and 28 girls, ages 7 to 13 years, for the knee and elbow flexor and extensors at 30°/second and 120°/second using an isokinetic procedure (Cybex II). In addition, the relationships of these torque levels to size and age were determined. The results revealed significant (p < .05) sex differences for the knee flexor and extensor torque values at 120°/second independent of body weight. That is, the boys generated 29.2 and 39.5 foot pounds vs. the girl's 26.2 and 35.4 foot pounds for knee flexion and extension, respectively. Similarly, torque differences (p < .05) between boys and girls were present for elbow extension at 120°/second when adjusting for differences in height. When examining the flexion/extension ratios, it is apparent that increases in body size (height, weight) and age had a significant effect on the ratio at 120°/second but not at 30°/second.     

Familial aggregation in physical activity.

The purposes of this study were to (a) examine the stability and consistency of the Caltrac accelerometer (Hemokinetics, Madison, WI) and an activity record to assess physical activity in children and adults (Experiment 1), and (b) to determine if there is a relationship between parents and their children in physical activity level (Experiment 2). Thirty 5-9-year-old children and their biological parents wore Caltrac accelerometers for three consecutive days (including one weekend day). At the same time, parents completed a Caltrac Activity Record (CAL REC) for themselves and their child. Dependent variables were counts per day for the Caltrac and minutes of light activity and activity for the CAL REC. Between-day correlations for the Caltrac ranged from r = .73 to .87 for the parents (p less than .001) and from r = .38 (p less than .04) to .79 (p less than .001) for the children. An analysis of variance with repeated measures indicated no significant differences for the Caltrac between days for parents and children. Between-day correlations for CAL REC ranged from r = .67 to .91 (p less than .05) for parents and r = .36 to .72 (p less than .05) for children, and there were no significant differences between days. In Experiment 2, chi 2 analyses were used to examine familial resemblance in physical activity. Using the Caltrac, familial resemblance occurred in 67% (father and child) and 73% (mother and child) of the families. Using the CAL REC, familial aggregation was present in 70% (father and child) and 66% (mother and child) of the families.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chinese Business Process Re-engineering

The popularity of business process re-engineering (BPR) and its international diffusion from the United States make it important to understand the influence of cultural factors on this concept. The global economic prominence of the Chinese and their distinctive cultural characteristics prompted our study of Chinese business process re-engineering. This article addresses a large gap in the Chinese management literature and is intended to help those who are managing organizations or marketing information technology (IT) products and related services in Greater China. We systematically compare IT-enabled change in the American and Chinese business cultures. Informal planning and process modelling, highly interdependent social and organizational relationships with ingrained hierarchies, and the prevailing attitudes towards information management and organizational change will shape the preparation for IT-enabled process innovation efforts as well as the design and implementation of IT-enhanced business process models in Chinese organizations.     

Validity of proximity sensor-based wear-time detection using the ActiGraph GT9X

Our study investigated the performance of proximity sensor-based wear-time detection using the GT9X under laboratory and free-living settings. Fifty-two volunteers (23.2 ± 3.8 y; 23.2 ± 3.7 kg/m²) participated in either a laboratory or free-living protocol. Lab participants wore and removed a wrist-worn GT9X on 3–5 occasions during a 3-hour directly observed activity protocol. The 2-day free-living protocol used an independent temperature sensor and self-report as the reference to determine if wrist and hip-worn GT9X accurately determined wear (i.e., sensitivity) and non-wear (i.e., specificity). Free-living estimates of wear/non-wear were also compared to Troiano 2007 and Choi 2012 wear/non-wear algorithms. In lab, sensitivity and specificity of the wrist-worn GT9X in detecting total minutes of wear-on and off was 93% and 49%, respectively. The GT9X detected wear-off more often than wear-on, but with a greater margin of error (4.8 ± 11.6 vs. 1.4 ± 1.4 min). In the free-living protocol, wrist and hip-worn GT9X’s yielded sensitivity and specificity of 72 and 90% and 84 and 92%, respectively. GT9X estimations had inferior sensitivity but superior specificity to Troiano 2007 and Choi 2012 algorithms. Due to inaccuracies, it may not be advisable to singularly use the proximity-sensor-based wear-time detection method to detect wear-time.