european college of sport science

IS-PH01 Skeletal muscle blood flow regulation during exercise
PROMOTING PHYSICAL ACTIVITY IN OLDER ADULTS: A LIFESTYLE APPROACH OR A STRUCTURED EXERCISE INTERVEN-
TION?
DELECLUSE, C., VAN ROIE, E., OPDENACKER, J., BOEN, F.
FACULTY OF KINESIOLOGY AND REHABILITATION SCIENCES
INTRODUCTION: Several studies have shown that older persons benefit from a supervised, center-based, exercise program in terms of
improved functional performance and fitness (Delecluse et al., 2004; Dunn et al., 1998; Fahlman et al., 2007). However, these supervised
center-based programs are expensive, which limits their implementation possibilities and hence their public health impact. Moreover, for
sedentary older adults in particular, a number of important barriers exist to attend such supervised center-based exercise program, for
example lack of access or transportation to the facilities, financial considerations and a lack of affinity with the culture of fitness centres
(Schutzer & Graves, 2004). In order to deal with these barriers, home-based and lifestyle interventions were developed. However, it is not
yet clear whether the effects of such home-based and lifestyle interventions equal the effects of supervised center-based exercise interventions.
The aim of this study was to evaluate the effects of traditional fitness training intervention versus a home-based lifestyle intervention
on physical activity, physical fitness and cardiovascular risk factors in older adults.
METHODS: One hundred and eighty-six sedentary men and women aged 60 to 83 volunteered to participate and were randomized in
one of three groups. A fitness training intervention (STRU, N = 60), consisting of three supervised sessions weekly, and a home-based
group (LIFE, N = 60), including an individualized lifestyle program supported by a limited number of booster phone calls, were compared
with an ‘assessment only’ control group (N = 66). Physical activity, cardio-respiratory fitness, muscular fitness, functional performance and
cardiovascular risk factors were recorded before (pretest) and after 11 months of intervention (posttest).
RESULTS and CONCLUSIONS: The STRU and the LIFE intervention were equally effective in increasing physical activity in older adults. Both
intervention groups improved in physical fitness, but STRU increased more than LIFE for cardio-respiratory and muscular fitness, whereas
LIFE increased more than STRU for functional performance. In general however, although STRU showed a limited effect on body composition
and total cholesterol/HDL ratio, eleven months of structured exercise and/or lifestyle physical activity had only limited effects on
cardiovascular risk factors,. Therefore, interventions aiming to reduce cardiovascular risks should focus on long-term changes in physical
activity behaviour.
REFERENCES
Delecluse, C., Colman, V., Roelants, M., Verschueren, S., Derave, W., Ceux, T. et al. (2004). Prev.Med., 39, 823-833.
Dunn, A. L., Marcus, B. H., Kampert, J. B., Garcia, M. E., Kohl, H. W., III, & Blair, S. N. (1999). JAMA, 281, 327-334.
Fahlman, M. M., Topp, R., McNevin, N., Morgan, A. L., & Boardley, D. J. (2007). J.Gerontol.Nurs., 33, 32-39.
Schutzer, K. A. & Graves, B. S. (2004). Prev.Med., 39, 1056-1061.
08:30 - 10:00
Invited symposia
IS-PH01 Skeletal muscle blood flow regulation during exercise
EXERCISE HYPEREMIA: PARTITIONING THE PERIPHERAL AND CENTRAL FACTORS
RICHARDSON, R.
UNIVERSITY OF UTAH
Numerous factors contribute to the essential increase in blood flow to active skeletal muscle at the onset of exercise, ensuring the adequate
supply of oxygen and removal of metabolic by-products. Central and peripheral factors, which may include the skeletal-muscle
pump, mechanically induced vasodilation, mechanical distortion of arterioles, flow mediated dilation, and cardio-acceleration resulting
from muscle mechanoreptor and chemoreceptor feedback, all have substantial support for their role in this hyperemic response. However,
as a result of the copious factors, it is difficult to experimentally partition them allowing one to determine the magnitude of effect and
temporal nature of any single mechanism. Thus, the aim of this presentation will be first to examine the blood flow response to exercise
and then to subsequently highlight the, second by second, kinetics of central and peripheral factors that influence hyperemia at the onset
of limb movement, providing mechanistic insight into the regulation of exercise hyperemia.
ROLE OF INTRAVASCULAR SIGNALS ON THE CONTROL OF MUSCLE PERFUSION
GONZÁLEZ-ALONSO, J.
BRUNEL UNIVERSITY
The matching of skeletal muscle oxygen supply and demand is a fundamental principle in Physiology. Recent studies suggest that the
oxygen carrying erythrocyte plays a role in this process by sensing and signaling the amount of oxygen bound to hemoglobin, i.e., oxyhemoglobin
(O2Hb). In this construct, adenosine triphosphate (ATP) release from erythrocytes in association with the offloading of oxygen
from the hemoglobin molecule is thought to play an important role in the matching of oxygen delivery to local muscle metabolic demand.
In vitro and in vivo observations support this hypothesis by demonstrating that i) erythrocytes release ATP in association with the offloading
of oxygen from the hemoglobin molecule, ii) plasma ATP is tightly correlated to alterations in O2Hb with exposure to hypoxia, hyperoxia
and carbon monoxide inhalation, and iii) ATP, when infused intra-arterially, causes both marked muscle vasodilatation and complete
inhibition of alpha-adrenergic vasocontriction. ATP exerts its vasodilatory effect directly and not via degradation compounds, as
comparison of the relative vasoactive potencies of ATP, and other nucleotides (ADP, AMP), adenosine and UTP, reveals the following rank
order of vasoactive potency: ATP (100) = UTP (100) >> adenosine (5.8) >ADP (2.7) >AMP (1.7). Furthermore, both ATP and UTP, but not ADP,
AMP or adenosine infusions, fully inhibit alpha-adrenergic vasoconstriction in a manner similar to exercise and hypoxia. Human skeletal
muscle expresses mainly P2Y2 purinergic receptors located in the vascular endothelium. The P2Y4, the only common ATP/UTP receptor,
cannot be detected at the mRNA level in skeletal muscle. Taken together, these findings support that erythrocyte-derived ATP acts as an
important mediator of oxygen sensing transduction between the erythrocyte and the muscle vascular endothelium causing both vaso-
120 14 TH
ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE