Four-year longitudinal associations of physical activity, waist circumference, and blood pressure in UK adolescents.

BACKGROUND: This study assessed the specific influence of physical activity (PA) and waist circumference (WC) on the 4-year growth trajectory of blood pressure in UK high-school students. METHODS: Four-year longitudinal monitoring of 1501 adolescents was conducted as part of the EoEHHS. Measurements were taken in Grades (G)7, 9, and 11. RESULTS: Systolic (SBP) and diastolic blood pressure (DBP) increased over the 4-year period (SBP G7 114.6 ± 8.9 mmHg, G9 118.1 ± 9.7 mmHg, G11 122.8 ± 7.8 mmHg; DBP G7 66.7 ± 6.6 mmHg, G9 68.0 ± 6.4 mmHg, G11 70.0 ± 5.2 mmHg). Baseline WC predicted baseline and growth in SBP, but the strongest contribution to SBP came from changes in WC (ß = 0.084, p = 0.002). Baseline PAQ-A score (ß = -0.822, p = 0.020) and changes in PAQ-A score (ß = -0.650, p = 0.019) were associated with smaller increases in DBP over the 4-year measurement period. CONCLUSIONS: Baseline and change in WC predicted the growth trajectory of SBP, while baseline and change in PA predicted the growth trajectory of DBP. PA and WC have a prognostic value in predicting changes in blood pressure in adolescents. Increasing PA during adolescence could slow the rise in DBP over time. This is meaningful for future hypertension and CVD risk reduction into adulthood. IMPACT: Hypertension in adolescents is a growing health problem that is often overlooked. Baseline and changes in waist circumference over a 4-year period predicted development of systolic blood pressure, while baseline and changes in physical activity predicted development of diastolic blood pressure. Physical activity and waist circumference have a prognostic value in predicting changes in blood pressure in adolescents and could be valuable in planning programmes to prevent hypertension in similar communities and reduce the risk of future adult hypertension.

Obese individuals do not underreport dietary intake to a greater extent than nonobese individuals when data are allometrically-scaled.

OBJECTIVE: The aim of this study was to assess the extent of misreporting in obese and nonobese adults on an absolute, ratio-scaled, and allometrically-scaled basis. METHOD: Self-reported daily energy intake (EI) was compared with total energy expenditure (TEE) in 221 adults (106 male, 115 female; age 53 ± 17 years, stature 1.68 ± 0.09 m, mass 79.8 ± 17.2 kg) who participated in a doubly-labeled water (DLW) subsection of 2013-2015 National Diet and Nutrition Survey. Data were log transformed and expressed as absolute values, according to simple ratio-standards (per kg body mass) and adjusted for body mass allometrically. Absolute and ratio-scaled misreporting were examined using full-factorial General Linear Models with repeated measures of the natural logarithms of TEE or EI as the within-subjects factor. The natural logarithm of body mass was included as a covariate in the allometric method. The categorical variables of gender, age, obesity, and physical activity level (PAL) were the between-factor variables. RESULTS: On an absolute-basis, self-reported EI (2759 ± 590 kcal·d-1 ) was significantly lower than TEE measured by DLW (2759 ± 590 kcal·d-1 : F1,205  = 598.81, p < .001, ηp 2 =0.75). We identified significantly greater underreporting in individuals with an obese BMI (F1,205  = 29.01, p <.001, ηp 2 =0.12), in more active individuals (PAL > 1.75; F1,205  = 34.15, p <.001, ηp 2 =0.14) and in younger individuals (≤55 years; F1,205  = 14.82, p < .001, ηp 2 =0.07), which are all categories with higher energy needs. Ratio-scaling data reduced the effect sizes. Allometric-scaling removed the effect of body mass (F1,205 =0.02, p = 0.887, ηp 2 =0.00). CONCLUSION: In weight-stable adults, obese individuals do not underreport dietary intake to a greater extent than nonobese individuals. These results contradict previous research demonstrating that obesity is associated with a greater degree of underreporting.

The effects of lower-body compression garments on walking performance and perceived exertion in adults with CVD risk factors.

OBJECTIVES: Compression garments are used by athletes in attempts to enhance performance and recovery, although evidence to support their use is equivocal. Reducing the exertion experienced during exercise may encourage sedentary individuals to increase physical activity. The aim of this study was to assess the effect of compression garments on walking performance (self-paced and enforced pace) and rate of perceived exertion (RPE) in adults who presented with two or more CVD risk factors. Participants (n=15, 10 female, 58.9±11.5 years, BMI 27.5±4.5kgm2) were recruited. DESIGN: A repeated measures design. METHODS: Participants were randomised to Modified Bruce Protocol (enforced pace), or the 6min walk test (self-paced), and completed the test wearing compression garments or normal exercise clothes (Control). Outcome measures included stage completed, gross efficiency (%) and RPE in Modified Bruce Protocol, and distance walked (m) and RPE in 6 min walk test. RESULTS: In the Modified Bruce Protcol participants had a higher RPE (15.5±2.5 vs 14.3±2.2) and a lower efficiency (19.1±5.9 vs 21.1±6.7) in the compression garment condition compared with control, p<0.05. In the 6 min walk test participants walked 9% less in the compression garment condition (p<0.05) but did not have a lower RPE. CONCLUSIONS: Compared with previous studies reporting enhanced or no effects of compression garments on performance or RPE, this study shows adverse effects of such clothing in untrained individuals with CVD risk factors. The mechanisms underlying this negative effect require further exploration. Use of garments designed for the athletic individuals may not be suitable for the wider population.