Thursday-Abstracts

Official Journal of the American College of Sports Medicine
CONCLusION: Our results indicate that transfer of adapted gait parameters to
overground gait following split-belt walking are greater than unilateral stepping,
however some populations with gait asymmetry may benefit from unilateral stepping if
they lack access to a split-belt treadmill.
D-17 Free Communication/Slide - Advancing
Physical Activity Assessment Methods
May 30, 2013, 1:00 PM - 3:00 PM
Room: 125
1375 Chair: Scott Crouter, FACSM. University of Massachusetts
Boston, Boston, MA.
(No relationships reported)
1376 May 30, 1:00 PM - 1:15 PM
Expressing Energy Expenditure in youth: allometric scaling
and Corrected METs
Brian C. Rider, David R. Bassett, Jr., FACSM, Dawn P. Coe.
University Of Tennessee, Knoxville, TN.
(No relationships reported)
Many physiological variables show associations with body size. It has been shown
that scaling submaximal VO2 values helps to normalize the data across individuals
of different size/age/gender. This reduces the likelihood that differences in VO2 will
appear to exist, when in fact, they are due primarily to differences in body size. This
could possibly be achieved by using allometric scaling or corrected METS (i.e. activity
EE/estimated RMR).
PurPOsE: To explore the use of allometric scaling and corrected METs to achieve
better estimates of children’s energy expenditure (EE) based on speed of locomotion,
during treadmill walking and running.
METhOds: Mean data were taken from 13 studies that contained childhood (8-
14y) VO2 data, obtained during submaximal treadmill tests. Due to the fact that each
study had different numbers of participants, studies with a greater number numbers
of subjects were assigned more weight. Linear regression was used to determine the
relationship between VO2 and treadmill speed. For the allometric scaling method,
body mass was expressed in ml.kg-0.75 min-1. Corrected METs were computed using
the Schofield equation to estimate RMR, using both weight (w) and height and weight
(h&w).
rEsuLTs: Both allometric scaling and corrected METs improved the ability to
estimate EE based on speed of locomotion. There was a tighter relationship between
speed and VO2 scaled to body weight raised to the 0.75 power, than there was between
speed and standard METs (i.e. activity EE/3.5) [Walking: r2= 0.6482, vs. 0.2859.
Running: r2= 0.8247 vs. 0.6281]. Corrected METs also showed tighter relationships
with speed than did standard METs [Walking: r2= 0.8722 (h&w) and 0.7942(w) vs
0.2859; Running: r2= 0.4773 (h&w) and 0.6421 (w) vs 0.6281].
CONCLusION: Both allometric scaling and corrected METs yielded stronger
associations with speed of locomotion, than standard METs. Corrected METs also
showed a stronger correlation with submaximal running speeds, but only when using
the Schofield equation based on weight. Further research is needed to determine the
best method available for normalizing energy costs of treadmill walking and running
for youth of different sizes/genders/ages.
1377 May 30, 1:15 PM - 1:30 PM
using receiver Operating Characteristic Curves and
accelerometry To Establish step-count Guidelines For
Twelve-year-old Children
Timothy Fulton, Fabio Fontana, Kent Ingvalson, Kimberly
Decker, Ripley Marston, Kevin Finn. University of Northern
Iowa, Cedar Falls, IA.
(No relationships reported)
Current physical activity guidelines are based on frequency, duration, and intensity
of physical activity. Recollection of physical activity duration and understanding of
physical activity intensity are difficult tasks. Restructuring current guidelines to stepcounts
may facilitate the identification of children not reaching adequate physical
activity levels.
PurPOsE: To measure the ability of step-counts to discriminate between adequate
and inadequate physical activity levels, and establish gender-specific step-count
guidelines for twelve-year-old children.
METhOds: This study employed a fully cross-sectional design. A total of 106
children participated in the study (N girls = 62; N boys = 44). Participants wore a pedometer
and an accelerometer for one full day, and recorded the number of steps on an
activity log. The Freedson equation was used to compute duration and intensity of
exercise. Receiver Operating Characteristic curves were used to determine the ability
of step-counts to discriminate between adequate and inadequate physical activity
Vol. 45 No. 5 Supplement S261
levels. Optimal cutoff points were based on sensitive scores larger than .80 due to the
importance of identifying children and adolescents with inadequate levels of physical
activity, and the maximum sum of sensitive and specificity scores.
rEsuLTs: The area under the curve for each of the sub-groups (AUCgirls = .85,
95% CI = .76 - .95, p > .01; AUCboys = .85, 95% CI = .72 - .97, p > .01) was high,
indicating good ability of step-counts to discriminate among children with adequate
and inadequate levels of physical activity. To achieve minimum daily physical activity,
we suggest 12,007 and 12,605 steps/day for 12-year-old girls and boys respectively.
CONCLusION: Pedometer step-counts discriminate well among children with
adequate and inadequate levels of physical activity. To our knowledge, this is the
first attempt to develop gender- and age-specific guidelines. With the current levels
of obesity on the rise, the use of the suggested step-count guidelines may be a useful
initial epidemiological step in the identification of children with low levels of physical
activity.
1378 May 30, 1:30 PM - 1:45 PM
Comparisons Of Prediction Equations For Estimating
Energy Expenditure In youth
Youngwon Kim 1 , Scott E. Crouter, FACSM 2 , Jung-Min Lee 1 ,
Yang Bai 1 , Glenn A. Gaesser, FACSM 3 , Gregory J. Welk,
FACSM 1 . 1 Iowa State University, Ames, IA. 2 University of
Massachusetts Boston, Boston, MA. 3 Arizona State University,
Tempe, AZ.
(No relationships reported)
Various sets of prediction equations for the Actigraph have been developed to estimate
energy expenditure (EE) in youth, but there is no consensus about the best approach. A
set of two 2-regression models (2RM) have been proposed as alternative to traditional
single regression models (1RM), but they have not been directly compared.
PurPOsE: The purpose of this study was to compare the VM (VM2RM) and VA
(VA2RM) and 1RM models from Freedson/Trost (FT), Trost (TR), Puyau (PU) and
Treuth (TH) to indirect calorimetry for estimating EE in youth.
METhOds: Fifty nine participants (7- 13 yrs; male: 41) performed 12 different
activities (randomly assigned from a set of 24) that would mimic “free-living”
activities in youth. While performing these activities, the participants were
concurrently measured with a metabolic gas analyzer (Oxycon Mobile; OM) and an
Actigraph accelerometer. Each activity was performed for 5-min, with a 1-min rest
between activities. Estimates of METs were obtained from the ActiGraph prediction
methods and were compared to OM measured METs (measured VO2/predicted
RMR). Comparisons were first made using the aggregated data from the whole trial
(i.e. between-subject comparisons; n = 59) and then for each individual activity (i.e.
activity-by-activity comparisons; n=24). Agreement with OM values was evaluated
using repeated measures of ANOVA (with Tukey-Kramer pairwise comparisons), and
absolute percent errors (APE).
rEsuLTs: For the whole trial comparisons, estimated EE from each of the ActiGraph
prediction methods significantly underestimated measured OM EE (P