Factors influencing diurnal variation in height among adults

This study evaluates height loss during the day in light of variables assessable through participant self-report. Participants were 19 female and 15 male staff and students who met with us twice with a mean interval between measurement sessions of 6.96 h (SD = 0.86). Hypotheses were evaluated using two-stage least squares regression analysis (SYSTAT 10). Males and females lost similar amounts of height between sessions $(\text{male},\overline{x}=6.9\text{mm};\text{female},\overline{x}=7.4\text{mm})$. Among factors considered to impact overall height loss, sleep duration (Adj. R² = 0.181, p = 0.022) and height (Adj. R² = 0.121, p = 0.048) were useful in univariate analyses, though they were not significant in any models that included variables other than sex. Judging from log-transformed BMI variation, heavier males and females lost more height (F_{(2, 31)} = 4.59, Adj. R² = 0.179, p = 0.018). Among factors anticipated to reduce height loss by acting prior to morning measurements, only time spent walking was significantly associated (β = 2.6 ± 0.8 mm, t = 3.16, p = 0.004) when included as a predictor along with sex (p = 0.17) and log-BMI (p = 0.003). This model explained about 38% of height loss variance. None of the factors considered as potentially acting between measurement sessions showed statistically significant influences when included in the model just described, though predictor coefficients were in the anticipated direction. Results suggest that self-reported activities may be an important supplement to anthropometric studies, both for planning and later evaluation, particularly in large studies.     

The effect of ice-slushy consumption on plasma vasoactive intestinal peptide during prolonged exercise in the heat

The aim of this study was to determine the effect of exercise in the heat on thermoregulatory responses and plasma vasoactive intestinal peptide concentration (VIP) and whether it is modulated by ice-slushy consumption. Ten male participants cycled at 62% $\dot{V}{\mathrm{O}}_2$max for 90 min in 32 °C and 40% relative humidity. A thermoneutral (37 °C) or ice-slushy (−1 °C) sports drink was given at 3.5 ml kg⁻¹ body mass every 15 min during exercise. VIP and rectal temperature increased during exercise (mean±standard deviation: 4.6±4.4 pmol L⁻¹, P=0.005; and 1.3±0.4 °C, P<0.001 respectively) and were moderately associated (r=0.35, P=0.008). While rectal temperature and VIP were not different between trials, ice-slushy significantly reduced heat storage (P=0.010) and skin temperature (time×trial interaction P=0.038). It appears that VIP does not provide the signal linking cold beverage ingestion and lower skin temperature in the heat.     

Assessment of the Monitor Unit Objective tool for VMAT in the Eclipse treatment planning system

Aim

This work aims to achieve the highest possible monitor units (MU) reduction using the MU Objective tool included in the Eclipse treatment planning system, while preserving the plan quality.