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1403
Board #56
June 2, 8:00 AM - 9:30 AM
Association Between Maximal Oxygen Consumption And Blood Pressure Reactivity To The Cold Pressor Test
Florian Milatz1, Sascha Ketelhut2, Reinhard G. Ketelhut, FACSM3. 1Medical School Hamburg, Hamburg, Germany. 2Martin-Luther University
Halle-Wittenberg, Halle, Germany. 3Medical Center Berlin, Berlin, Germany.
Email: milatzfl@gmail.com
(No relationships reported)
PURPOSE: The favorable influence of acute as well as regular moderate aerobic endurance exercise on blood pressure (BP) regulation is widely known. It is also well
accepted that stress contributes to the development of arterial stiffness and increases the risk of cardiovascular events. In recent studies BP hyper-reactivity to the cold
pressor test (CPT) has been suggested as a predictor of hypertension. Therefore we examined whether aerobic capacity, quantified by maximal oxygen consumption
(VO2max) is associated with BP reactivity to the CPT.
METHODS: 27 recreationally active men completed a cardiopulmonary exercise testing on a bicycle ergometer. Peripheral and central BP were measured non-invasively at
rest and at the end of a 2 minute CPT using an oscillometric device. Statistical testing about the relationship between VO2max and BP reactivity was performed by applying
partial correlation analysis adjusted for age, body mass index and bodyweight.
RESULTS: After adjustment for covariates, VO2max showed negative correlations with systolic BP reactivity. This was true for both peripheral (r = -0.63, p = 0.001) and
central (r = -0.55, p = 0.005), respectively. Regarding diastolic BP neither peripheral (r = -0.38, p = 0.067) nor central (r = -0.32, p = 0.125) BP-reactivity correlated significantly
with VO2max.
CONCLUSIONS: The present study provides evidence for an inverse relationship between VO2max and systolic BP-reactivity to the cold stimulus. Higher physical
conditioning status, indexed by VO2max seem to be associated with more favorable effects on arterial compliance during stress testing and might be beneficial on long-term
BP regulation during stress.
1404
Board #57
June 2, 8:00 AM - 9:30 AM
Acute Cheese Consumption Ameliorates Sodium-Induced Cutaneous Microvascular Dysfunction by Reducing Ascorbate-Sensitive
Oxidants
Billie K. Alba, Anna E. Stanhewicz, W. Larry Kenney, FACSM, Lacy M. Alexander, FACSM. Pennsylvania State University, University Park,
PA.
(No relationships reported)
In epidemiological studies, chronic dairy intake is associated with improved cardiovascular outcomes; conversely, high dietary sodium (Na) consumption impairs endothelial
function through increased oxidative stress and reduced nitric oxide (NO)-dependent mechanisms.
PURPOSE: To examine if the high Na in cheese has a less negative effect on microvascular dysfunction relative to equivalent Na from non-dairy sources due to the actions of
milk-based macronutrients and proteins. We hypothesized that 1) acute dairy based cheese ingestion augments NO-dependent vasodilation (VD) compared to an equal
amount of Na from non-dairy sources, and 2) the Na-induced decrease in NO-dependent VD is mediated by oxidant stress mechanisms.
METHODS: On 5 separate visits, 14 subjects (61±2 yrs) consumed either 85 g cheddar cheese (560 mg Na), 85 g soy cheese (560 mg Na), 65 g pretzels (560 mg Na), 170 g
cheddar cheese (1120 mg Na), or 130 g pretzels (1120 mg Na). Two intradermal microdialysis fibers were inserted in the forearm skin for local delivery of 1) lactated Ringer’s
solution (control site) and 2) ascorbate (antioxidant site). Red blood cell flux was measured by laser-Doppler flowmetry (LDF) during local skin heating (42°C) to induce
endothelial NO synthase-dependent VD. Once a plateau in cutaneous vascular conductance (CVC = LDF/MAP) occurred, 20 mM L-NAME was perfused at both sites to
directly quantify NO-dependent VD. Data were expressed as a percentage of maximum (%CVCmax; 28mM SNP).
RESULTS: The total vasodilatory response was not different among the five dietary treatments. NO-dependent VD was higher following dairy cheese consumption compared
to a Na-equivalent in soy cheese (59±5 vs. 44±6%; p=0.03) or pretzels (560 mg Na: 59±5 vs. 45±4%; p=0.03, 1120 mg Na: 57±4 vs. 46±5%; p=0.02). Local ascorbate
administration abolished these differences (no main dietary treatment effect).
CONCLUSION: Na ingestion in cheese was associated with a higher NO-dependent VD compared to an equal amount of non-dairy Na, a difference that was abolished with a
local non-specific antioxidant. These data suggest that macronutrients in dairy based cheese may protect against acute Na-induced microvascular dysfunction through
antioxidant mechanisms.
Supported by Dairy Management Inc.
C-28
Basic Science World Congress/Poster - Energy Balance: Pediatrics and Children
Thursday, June 2, 2016, 7:30 AM - 12:30 PM
Room: Exhibit Hall A/B
1405
Board #58
June 2, 9:00 AM - 10:30 AM
Objectively-Measured Physical Activity Predicts DXA-Measured Fat Mass from Age 5-17 Years: Iowa Bone Development Study
Kathleen F. Janz, FACSM1, Elena M. Letuchy1, Trudy L. Burns1, Soyang Kwon2, Julie M. Gilmore-Eichenberger1, James C. Torner1, Steven M.
Levy1. 1University of Iowa, Iowa City, IA. 2Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL.
Email: kathleen-janz@uiowa.edu
(No relationships reported)
The high prevalence of childhood obesity supports the need to understand which dimensions of physical activity (PA) and sedentary time (SED) are most robustly associated
with adiposity.
PURPOSE: This 12-yr longitudinal study examined associations among PA, SED, fat mass and visceral adipose tissue (VAT) from childhood through adolescence (ages 5 to
17 yr). We tested the premise that PA was more highly associated with fatness than SED. We also examined if specific intensities of PA (moderate-to-vigorous intensity PA
(MVPA) and light PA) and a component of SED (TV viewing) have greater effects on adiposity than overall measures.
METHODS: Participants in the Iowa Bone Development Study at ages 5, 8, 11, 13, 15 & 17 yr (n = 327, 398, 405, 399, 317, 285, respectively) were studied. MVPA (min/d),
light PA (min/d), and SED (hr/d) were measured using acclerometry. TV viewing (TV) was measured via parent-proxy report (5 & 8 yr) and child-report (11, 13, 15, & 17 yr).
Anthropometrics measured body size and somatic maturity. DXA measured fat mass and VAT. Gender-specific multi-level growth models were used to create fat mass and
VAT growth curves for individual participants (level 1), and test the effect of PA, SED, & TV (level) after considering weight, height, linear age, non-linear age, and maturity. At
each age, clinical significance was examined by calculating the differences in absolute fat mass and VAT between low (10th %ile) and high (90th %ile) active and SED
participants.
373
Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
RESULTS: Due to non-normal distribution, fat mass, VAT, and MVPA were transformed. Growth models indicated that for boys and girls, high levels of MVPA were
associated with low levels of fat mass and VAT (p<0.01); however, light PA and TV were positively associated with adiposity (p<0.05). On average, there was a difference in
(absolute) fat mass of 18% between high MVPA/low TV boys compared to low MVPA/high TV boys. This difference was 12% in girls.
CONCLUSIONS: High levels of MVPA and low levels of TV independently and summatively contribute to low levels of adiposity. Unexpectedly, high levels of light activity are
associated with high levels of adiposity. This study suggests that reducing the prevalence of childhood obesity may require focusing on specific dimensions of PA. It also
supports current PA guidelines focusing on MVPA rather than SED.
1406
Board #59
June 2, 9:00 AM - 10:30 AM
Energy Expenditure Associated With Froude Number And Traditional Speed Measures In Children And Adolescents.
Michael A. Green1, Michael Busa1, John Schuna2, Catrine Tudor-Locke, FACSM1. 1University of Massachusetts at Amherst, Amherst, MA.
2
Oregon State University, Corvallis, OR. (Sponsor: Catrine Tudor-Locke, FACSM)
(No relationships reported)
Energy expenditure or metabolic cost of walking is related to speed of locomotion. Leg length normalized speed measures may improve the ability to predict the metabolic
cost of walking across the developmental age range. Metrics that improve the strength of the relationship between subject size, walking speed and its metabolic cost may
enhance the ability to provide universal recommendations of walking behavior that may serve to improve health.
PURPOSE: The purpose of this study was to compare the predictive value of speed in standard units (STD, m/s) to leg length (LL) normalized speed values: the Froude
number (Fr) and Dimensionless Speed (DLS) on the metabolic cost of walking in persons 6-20 years of age. We hypothesize that Fr and DLS will improve the prediction of
metabolic cost of bipedal transport in children and adolescents.
METHODS: : 120 children and adolescents (50% female, 13.1 ± 4.2 years, height 155.6 ± 16.6 cm, mass 56.3 ± 22.3 kg, LL 74.1 ± 9.0 cm) participated in this study. O2
consumption was measured by a K4 portable metabolic system (COSMED). Individuals completed an incremental treadmill protocol 0.22-2.23 m/s, in 0.22m/s increments.
The square root of the metabolic data (ml*kg-1*min-1) were compared with all ambulatory speed measures: STD, Fr and DLS. The Akaike information criterion (AIC) was
used to compare the linear and quadratic regression models of each gait measure and square root of metabolic cost of walking, best models were selected based on AIC
weights.
RESULTS: : AIC values indicated that quadratic model provided a better fit for all models of speed and the metabolic cost of walking. AIC weights indicated that DLS (AIC = 489.59) was 315 and 2.45 * 106 times better than Fr (AIC = -478.08) and STD (AIC = -460.16), predicting the metabolic cost of locomotion.
CONCLUSIONS: The DLS method of scaling gait speed to leg length offers significant improvements in the ability to predict metabolic cost of locomotion in children and
adolescents ages 6-20. Improving the ability to predict metabolic cost from gait parameters may enhance the ability to provide public health recommendations based on
objectively measured gait parameters.
Funded by Eunice Kennedy Shriver National Institute of Child Health and Human Development: 1R21HD073807-01A1
1407
Board #60
June 2, 9:00 AM - 10:30 AM
Intensity and Bouts of Physical Activity and Physical Activity Level in Pre-adolescent Children
Keisuke Komura1, Satoshi Nakae2, Kazufumi Hirakawa3, Naoyuki Ebine1, Kazuhiro Suzuki4, Haruo Ozawa5, Yosuke Yamada2, Misaka
Kimura3, Kojiro Ishii1. 1Doshisha University, Kyoto, Japan. 2National Institutes of Biomedical Innovation, Health and Nutrition, Tokyo, Japan.
3
Kyoto Gakuen University, Kyoto, Japan. 4Yamagata University, Yamagata, Japan. 5Tokai University, Kanagawa, Japan. (Sponsor: Susumu
Sawada, FACSM)
Email: k-komura@po.kbu.ac.jp
(No relationships reported)
Increasing pre-adolescent children’s physical activity level (PAL) is an important way to prevent adolescent obesity. It is therefore necessary to investigate the types of
physical activity of pre-adolescent children that are associated with PAL, with particular attention paid to the intensity and bouts of physical activity.
PURPOSE: The objective of this study was to elucidate the intensity and bouts of physical activity associated with PAL in pre-adolescent children.
METHODS: This study was a cross-sectional study of 42 elementary school children aged 10 to 11 years old (26 boys, 16 girls). We defined PAL as the total energy
expenditure as measured using the doubly labeled water (DLW) method, which is the gold standard for the measurement of field metabolic rate, divided by the basal
metabolic rate. In order to measure the intensity and duration of physical activity performed during DLW measurement, we used uniaxial accelerometers to evaluate sedentary
behavior (SED), light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA). MVPA was categorized by bouts of increasing duration:
Sporadic (<4 min), short (≥4 and <10 min), and medium-to-long bouts (≥10 min). Partial correlation adjusted for sex and the accelerometer wearing time was used to analyze
the association between PAL and the physical activity variables.
RESULTS: SED showed a significant negative association with PAL (r=-0.409, p<0.01), and LPA showed a significant positive association with PAL (r=0.329, p<0.05).
Although no significant association between total MVPA and PAL was observed, medium-to-long bouts of MVPA showed a significant positive association with PAL (r=0.322,
p<0.05).
CONCLUSION: Although the correlations were not strong, these results suggest a negative relationship between SED and PAL, and also a positive relationship between LPA
and medium-to-long bouts of MVPA and PAL among pre-adolescent children.
1408
Board #61
June 2, 9:00 AM - 10:30 AM
Compensatory Responses to Intermittent Physical Activity in Elementary School-Age Children
Molly P. O’Sullivan, Matthew R. Nagy, Shannon S. Block, Trevor R. Tooley, Rebecca E. Hasson. University of Michigan, Ann Arbor, MI.
Email: mollyosu@umich.edu
(No relationships reported)
The ActivityStat hypothesis suggests that when physical activity (PA) is increased in schools in the form of physical education or recess, there will be a compensatory
decrease in PA performed outside of school toward a homeostatic set-point to regulate physical activity energy expenditure (PAEE) over time. It is unclear whether children
compensate in response to intermittent PA, a pattern of movement that resembles children’s activity in free-living environments.
PURPOSE: The purpose of this laboratory-based study was two-fold: (1) to determine the acute effect of intermittent activity breaks on PAEE in children and (2) to examine
the effect of exercise intensity on PA compensation.
METHODS: Thirty-nine children (18 males, 21 females; ages 7-11 years; 33% overweight/obese; 59% non-white) completed four experimental conditions in random order: (1)
8 hours of sitting interrupted with 2-minute light-intensity activity breaks performed at 25% maximal heart rate (HRmax) every 18 minutes; (2) 8 hours of sitting interrupted with
2-minute moderate-intensity activity breaks (50% HRmax); (3) 8 hours of sitting interrupted with 2-minute high-intensity activity breaks (75% HRmax); and (4) 8 hours of sitting
interrupted with 2 minutes of sedentary screen time. PAEE was assessed via accelerometry for 7 pre-testing days to establish baseline PAEE and throughout the condition
day (8 hours in-lab and the remainder of the condition day at home).
RESULTS: Compared to baseline (293±19 kcals), PAEE was significantly lower on the sedentary condition day (212±22 kcals; p<0.05) and significantly higher on the highintensity condition day (415±26 kcals; p<0.05). There were no significant differences in PAEE observed on the low- (259±22 kcals; p>0.05) and moderate-intensity (305±24
kcals; p>0.05) condition days compared to baseline.
374
Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
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