Thursday-Abstracts

Official Journal of the American College of Sports Medicine
can reduce bronchoconstriction and airway inflammation on their own. The variable
responses obtained in this study suggest that for subjects not reaping the full benefits
from either supplement alone, a combination of fish oil and vitamin C may be more
effective.
1267 Board #213 May 30, 8:00 AM - 9:30 AM
decrements In Pulmonary diffusing Capacity With duration
Of disease In Type-1 diabetes
Michelle J. Lee1 , J Christopher Baldi, FACSM2 , J Richard,
Coast, FACSM1 . 1Northern Arizona University, Flagstaff, AZ.
2University of Otago, Dunedin, New Zealand.
(No relationships reported)
Diabetes is known to affect peripheral tissues by damaging capillaries and basement
membranes, however, its effects on the lung are less known. Lung diffusing capacity
(DLCO) is influenced by alveolar-capillary membrane conductance (DM) and
pulmonary capillary blood volume (VC), both of which have shown impairments in
adults with type-1 diabetes (T1D).
PurPOsE: We sought to determine the effect of T1D, age, and diabetes duration on
DLCO, DM, VC, and cardiac output (Q).
METhOd: We recruited 48 subjects, 24 people with T1D (ages 10.7 – 52.8 years old)
and 24 non-diabetic controls matched for age, gender, and fitness level and measured
DLCO, DM, VC, and Q at rest and three exercise workloads (40% VO2max, 70%
VO2max, and 90% VO2max).
rEsuLTs: When stratified into two groups based on age (young < 20.6 years old),
there were no significant differences in DLCO, DM, VC, or Q (all of which were
normalized to body surface area [BSA]) in the young group, or in the old group. When
stratified into two groups based on diabetes duration (short duration range 0.33 – 8.9
years, long duration range 9.6 – 28 years), the T1D in the long duration group had
significantly lower DLCO/BSA and DM/BSA compared to the matched controls (16.5
± 0.6 and 19.0 ± 0.6 mL/min/mmHg/BSA, p= 0.014 and 22.5 ± 0.9 and 25.6 ± 0.9 mL/
min/mmHg/BSA, p= 0.033, respectively) with no differences in VC/BSA and Q/BSA.
There were no differences in any of the variables in the short duration group.
CONCLusION: While we initially hypothesized that age would be a factor in the
decrements in lung function, this study has shown that independent of age, duration
of diabetes is a factor more associated with decrements in diffusing capacity and its
components. Supported by NIH Grant R15 HL097335-01A1.
1268 Board #214 May 30, 8:00 AM - 9:30 AM
Carbon Monoxide reduces O 2 Extraction but not Peripheral
Tissue diffusing Capacity at VO 2 max
George H. Crocker, James H. Jones. University of California,
Davis, CA.
(No relationships reported)
PurPOsE: We hypothesized that breathing hypoxic gas and/or carbon monoxide
(CO) would similarly affect peripheral tissue (skeletal muscle) O2 extraction (EO2,
fraction of O2 delivered that is consumed) and diffusing capacity for O2 (DTO2),
despite altering aerobic capacity by different mechanisms – decreased blood O2
saturation (hypoxia) vs. decreased circulatory capacitance (CO).
METhOds: We ran six goats on a treadmill at speeds eliciting maximal aerobic
capacity while breathing inspired O2 fraction (FIO2) of 0.21 or 0.12 and maintaining
carboxyhemoglobin fraction (FHbCO) of 0.02 or 0.30. We measured O2 consumption
(VO2) and sampled arterial and mixed-venous blood to calculate cardiac output (Q) via
Fick Principle and total cardiopulmonary O2 delivery (TO2, product of Q and arterial
[O2]). We calculated for each gas EO2 as VO2/TO2 and DTO2 as VO2/mixed-venous
O2 tension (PvO2).
rEsuLTs: Compared to room air (EO2 0.90 ± 0.03), EO2 decreased with FHbCO
0.30 when breathing either FIO2 0.21 or 0.12 (EO2 0.79 ± 0.04 and 0.81 ± 0.03) and
increased with hypoxia alone (EO2 0.92 ± 0.02). The VO2 and PvO2 were highly
correlated and the slopes of the regressions were significant for five of six goats
(0.951 < R2 < 0.994, P < 0.001 for each). The DTO2 did not differ between the four
FIO2/FHbCO combinations (P = 0.867). We analyzed data from previous studies that
calculated DTO2 as the slope of VO2 vs. PvO2 for various inspired gases. Compared
to the means of individual points, DTO2 estimates based on slope are biased high when
the VO2 vs. PvO2 intercept is negative and low when the VO2 vs. PvO2 intercept is
positive.
CONCLusIONs: The EO2 differed for hypoxia and elevated FHbCO, indicating
goats had to deliver more O2 with elevated FHbCO than with hypoxia to reach
similar VO2, suggesting CO impairs (and hypoxia improves) the ability to extract
and consume O2 compared to normoxia. However, DTO2 was unchanged by FIO2
or FHbCO. Oxyhemoglobin affinity effects on diffusion pressure head explain the
EO2 differences observed. Because non-zero intercepts of VO2 vs. PvO2 bias DTO2
estimates, future studies should calculate DTO2 both as the average of individual gas
mixtures as well as the slope of VO2 vs. PvO2 for all gases. Supported by the U.S.
Army Medical Research and Materiel Command (Contract No. W81XWH-11-D-0011)
through L-3/Jaycor.
Vol. 45 No. 5 Supplement S245
1269 Board #215 May 30, 8:00 AM - 9:30 AM
Breathing Pattern and strategy during Exercise In young
swimmers and Non-swim Trained Children
Joel M. Stager, FACSM, Kosuke Kojima, Masataka Ishimatsu,
Daniel P. Wilhite, Brian V. Wright. Indiana University,
Bloomington, IN.
(No relationships reported)
Swim training has been suggested to promote proportionate lung growth though the
training effects on pulmonary function remain controversial (Courteix et al., 1997;
Silvestri et al., 2012). Specifically, breathing patterns and strategies during incremental
exercise in young swimmers as compared with non-swim trained children have not
been documented.
PurPOsE: To characterize the breathing patterns and strategies of young swimmers
during incremental exercise to volitional exhaustion and compare those measures to
age- and size-matched non-swim trained children.
METhOds: Twenty four healthy non-asthmatic, young, competitive swimmers (12
girls and 12 boys; 10.5 yrs, 144.5 cm, 38.0 kg) and 11 non-swim trained children (4
girls and 7 boys; 10.2 yrs, 141.1 cm, 33.3 kg) performed resting pulmonary function
and incremental exercise tests to volitional exhaustion (VO 2peak ) on a cycle ergometer.
Pulmonary function was collected during a set of maximal inspiratory and expiratory
maneuvers for the determination of the maximal flow-volume loop. Metabolic
and ventilatory data were recorded at each minute during the VO 2peak test. Exercise
inspiratory and expiratory tidal volume (V Tinsp and V Texp ) and peak flow (PF Tinsp and
PF Texp ) were measured during the last 30 sec of each minute, and inspiratory and
expiratory reserve volumes (IRV and ERV) were determined using inspiratory capacity
maneuvers.
rEsuLTs: At rest, swimmers showed significantly greater forced vital capacity (2.37
± 0.40 vs. 1.84 ± 0.56 L) and maximal mid expiratory flow (2.90 ± 0.71 vs. 2.34 ± 0.65
Lsec-1). The groups were similar in relative VO2 (47.3 ± 7.95 vs. 43.7 ± 9.09 mlmin-
1kg-1 at peak), breathing frequency, and IRV at 60, 70, 80, 90 and 100% of VO2peak.
Greater minute ventilation (70.6 ± 19.3 vs. 53.6 ± 11.2 L at VO2peak), tidal volume
(1.29 ± 0.32 vs. 0.99 ± 0.19 L at VO2peak), ERV, VTinsp, VTexp, PFTinsp, and
PFTexp were observed in swimmers throughout the exercise bout (p < 0.05).
CONCLusION: With no difference in breathing frequency, the higher tidal flow in
young swimmers permitted a higher tidal volume, thus allowing for greater minute
ventilation during incremental exercise. Young swimmers seem to exploit a higher
available expiratory airflow by breathing at higher lung volumes possibly as a means
of avoiding mechanical constraints to ventilation.
1270 Board #216 May 30, 8:00 AM - 9:30 AM
Effects Of heliox On respiratory Mechanics and Cycling
Performance In Endurance-trained Men and Women
Sabrina S. Wilkie, Paolo B. Dominelli, Benjamin C. Sporer,
Michael S. Koehle, A. William Sheel. University of British
Columbia, Vancouver, BC, Canada.
(No relationships reported)
Mechanical ventilatory constraints develop in some endurance-trained (ET) men
during strenuous exercise. Both ET and untrained women have been shown to develop
expiratory flow limitation (EFL) during maximal and sub-maximal exercise. Women’s
increased susceptibility to EFL can be attributed to structural and functional sex-based
differences with respect to the pulmonary system. Consequently women’s endurance
performance may be limited to a larger extent than men’s through increases in the work
of breathing (WOB) and higher sensations of leg and breathing discomfort.
PurPOsE: To determine the effects of partially unloading the respiratory system
using a heliox (He-O2; 79% He, 21% O2) inspirate on EFL, the WOB, operational
lung volumes, sensory responses (leg and breathing discomfort) and cycling
performance between men and women.
METhOds: Competitive cyclists (n = 11 men; n = 11 women) completed two 5-km
time trials (TT), breathing either room air (RA) or He-O2. The maximum expiratory
flow-volume (MEFV) curve method was used to determine EFL. The WOB was
measured with an esophageal balloon catheter.
rEsuLTs: During both the RA and He-O2 TTs EFL developed in men (RA: n =
36%; He-O2: n = 45%) and women (RA: n = 60%; He-O2: n = 40%). The magnitude
of EFL was variable throughout both TTs for all subjects due to alterations in endexpired
lung volume and expiratory flow rates. At 5-km women’s minute ventilation
was significantly lower than men’s (RA-women: 94.417.8; men: 134.412.7; p