Thesis-1995-Tsetsonis.pdf (6.63 MB)
The influence of the intensity of treadmill walking and training status on lipoprotein metabolism in the fasted and postprandial states
thesis
posted on 2012-10-31, 12:26 authored by Natassa V. TsetsonisThe aim of the studies described in this thesis was to investigate the effects
of the intensity of treadmill walking and training status on lipoprotein
metabolism in the fasted and postprandial states in normolipidaemic
individ uals.
Twelve young (28±2 years) adults walked on the treadmill on two
occasions, for 90 min at low intensity (30% maximal oxygen uptake,
V02max) and moderate intensity (60% V02max) after an overnight fast.
Venous blood samples were taken during, immediately, 1 and 24 hours
after the end of each walk, all in the fasted state. Both exercise bouts
reduced the serum triacylglycerol (TAG) concentrations 24 hours after
exercise but these decreases were independent of the intensity of the
previous exercise bout.
In the light of the suggestion that the fasted state may not be a sensitive
model to study the TAG metabolic capacity, the above experiment was
repeated in young adults (n=12), with the two bouts of treadmill walking
taking place 16 hours prior to the ingestion of a high fat meal 0.3 g fat·kg
body weight·l , 67% energy from fat). In addition a third trial was
introduced in which volunteers did not exercise prior to the ingestion of
the meal (control trial). Venous samples were obtained in the fasted state
and after the ingestion of the meal at hourly intervals for 6 hours.
Moderate, but not low intensity, walking significantly attenuated (26%) the
total lipaemic response to the meal compared with the control trial
(5.51±0.5 mmoJ.l-l.h vs 7.40±0.7 mmol·J-l·h; p<0.05). However, the
moderate intensity bout expended twice the energy expended during low
intensity exercise as the two bouts were of similar duration (90 min).
The third study, therefore, examined the effect of the intensity of walking
on the lipaemic responses to a similar high fat meal in young adults (n=9),
when the energy expenditure of the two walking bouts was held constant
(90 min at 60% V02max vs 180 min at 30% V02max). In addition, expired air
samples were collected before and after the meal in order to examine the
metabolic responses to this meal. Both bouts of exercise attenuated to a
similar degree (=30%) the total serum TAG response to the meal compared
with the non-exercise trial (5.46±0.63 mmol·J-l·h and 5.53±0.58 mmol-l-l.h
at low and moderate intensity respectively vs 8.09±1.09 mmol·J-l·h;
p<0.05). Mean respiratory exchange ratio over 6 hours after the meal was
lower (p<0.05) in both exercise trials than in the control trial indicating an
enhanced fat oxidation during the observational period.
All the above three studies were conducted in young adults. The aim of
the last study was two-fold (i) to examine whether a bout of moderate
intensity walking (60% V02max) would influence the lipaemic and
metabolic responses to a fat meal in middle-aged women, as already
shown for young adults and (ii) to test the hypothesis that this effect
would be greater in trained individuals, by comparing these responses
between a trained (n=9) and an untrained (n=13) group. Walking
attenuated the total postprandial TAG response to the meal compared to
the control trial in both trained (4.9±O.3 mmol·j-1·h vs 7.0±O.S mmol·j-1·h;
p
History
School
- Sport, Exercise and Health Sciences
Publisher
© N.V. TsetsonisPublication date
1995Notes
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.283992Language
- en