Wayland Tseh

Perceived stress and blood pressure in early adolescent children

The objective of this investigation was to determine the individual contributions of perceived daily, major, and total stressors to blood pressure in early adolescent children. Toward this goal, cardiovascular risk factors were assessed in 74 6thgrade students. Height and body weight, measured in standard fashion, were used to calculate body mass index (BMI). Waist and hip circumferences and triceps and calf skinfolds were take to determine the distribution and percentage of body fat, respectively. Seated resting blood pressure was obtained using a mercury sphygmomanometer. The dietary sodium-to-potassium ratio was calculated from a food intake questionnaire. Family history of hypertension was self-reported by participant’s parents, and physical activity and perceived stress levels were determined by questionnaire. When added to the hierarchical regression models, the perceived stress variables did not significantly predict any additional variance in systolic or diastolic blood pressure in this early adolescent sample. Additionally, bivariate correlations between the stress variables and blood pressure were nonsignificant. The nonpsychological hypertension risk factors accounted for 25%–35% of the total variance in systolic and diastolic blood pressure. Further, regression analyses revealed that with the exception of BMI and the sodium-to-potassium ratio, no other risk factors were independent predictors of systolic or diastolic blood pressure. Further identification and understanding of environmental precursors of childhood hypertension is recommended.

Rollers Versus Trainers: 10-KM Time Trial

The primary aim of this investigation was to determine which cycling training device, Rollers or Trainers, was most effective in improving 10-km time trial. Eight male and 6 female volunteers (N = 14; age = 23.6 ± 4.6 yrs; height = 172.7 ± 9.9 cm; body mass = 68.4 ± 10.4 kg; % body fat = 16.9 ± 7.7; VO2max = 61.0 ± 9.4 ml·kg−1·min−1) provided informed consent prior to participation. Participants performed a10-km time trial at baseline and were then randomly assigned into one of three groups: Rollers (R), Trainers (T), or Control (C). Participants assigned to the R or T groups attended 24 supervised workout sessions throughout an 8-wk period (F: 3 days/week; I: 65–80% HRmax; D: 40 min; M: R or T). There were no significant differences in baseline 10-km time trial between R, T, and C groups [F(2,12) = 0.34, p = .72]. There was a significant difference in 10-km time trial improvement between groups post-assessment when controlling for baseline values (F = 17.04, p <.001). R participants improved by 20.4s [t(4) = 4.86, p = .008] and T participants improved by 12.8s [t(4) = 4.57, p = .01], while there was no significant improvement for subjects in C. Participants using R and T displayed significant decrements in time with respect to the 10-km time trial. However, R had a greater improvement in 10-km time trial when compared to T.

METABOLIC ACCOMMODATION OF YOUNG CHILDREN TO TREADMILL WALKING 1167

Few data exist concerning the reproducibility of stable oxygen uptake (VO(2)) values during level treadmill walking in young able-bodied children. To address this issue, 41 able-bodied 6-year-olds (19 boys, 22 girls, X height=117.2+/-4.7 cm, X body mass=21.8+/-2.5 kg) were tested on two occasions. In session 1, subjects were familiarized with the laboratory environment and performed 5 min of level treadmill walking at 1.34 m s(-1). During session 2, each child completed 30 min (three 10-min trials) of level treadmill walking at 1.34 m s(-1). For each 10-min trial, mean VO(2) was determined by averaging VO(2) values obtained from analysis of two 2-min expired gas samples. While the mean VO(2) for trial 1 was higher than values recorded for trials 2 and 3, effect sizes corresponding to these differences were low (</=0.16). Average within subject coefficient of variation and intraclass reliability coefficient values for VO(2) across the three walking trials were 2. 0+/-1.5% and 0.96, respectively. Viewed collectively, these results suggests that among young able-bodied children, acceptably and reproducible stable VO(2) values during level treadmill walking can be obtained within 10 min if data collection is preceded by exposure to testing procedures and a brief period of treadmill walking practice.