Thesis-2004-Li.pdf (3.96 MB)
The effects of repeated bouts of prolonged cycling and carbohydrate supplementation on immunoendocrine responses in man
thesis
posted on 2013-05-24, 11:29 authored by Tzai-Li LiProlonged strenuous exercise affects the circulating numbers and functions of immune
cells. These effects are thought to be largely mediated by the actions of elevated circulating
stress hormones and alterations in regulatory cytokines. Although the effects of a single
acute bout of exercise on immune system function are quite well established, it is still not
clear how time of day and repeated bouts of prolonged exercise on the same day influence
immune function. It is of particular interest to understand the effects of nutritional
supplementation on immunoendocrine responses. Therefore, the aims of the studies
described in this thesis were to determine the effects of two bouts of prolonged cycling and
carbohydrate supplementation on immunoendocrine responses.
The saliva collection study showed that the use of a swab for collecting saliva is not an
ideal method because it affects the results of saliva composition (Chapter 4). The
comparison of the effects of exercise at different times of day on immunoendocrine
responses showed that a single bout of prolonged exercise performed in the afternoon
induces a larger perturbation in the redistribution of leukocytes into the circulation than an
identical bout of morning exercise, which maybe due to higher hypothalamic-pituitaryadrenal
(HP A) activation and. circadian rhythms. However, in terms of oral mucosal
immunity, performing prolonged cycling at different times of day does not differently
affect the salivary responses. The second compared with the first of two bouts of prolonged
exercise on the same day induces a greater HP A activation, a larger leukocyte trafficking
into the circulation, a decreased neutrophil degranulation response to lipopolysaccharide
(LPS) on per cell basis and a lower saliva flow rate, but does not increase plasma
interleukin-6 (IL-6), or change saliva immunoglobulin A (slgA) secretion rate (Chapter 5).
Furthermore, carbohydrate (CHO) ingestion during any period of two bouts of prolonged
exercise shows limited beneficial effect in blunting these higher responses in the second
exercise bout compared with the first identical exercise bout on the same day (Chapter 6, 7
and 8). The determination of the effects of CHO ingestion on exercise-induced
immunoendocrine responses showed that when two bouts of exercise are performed on the
same day, the greater benefit in terms of circulating immunoendocrine responses is
obtained by feeding CHO at the earliest opportunity (Chapter 6, 7 and 8). A 3-h interval is insufficient for recovery of leukocyte mobilisation and neutrophil function from the impact
of previous exercise whether subjects consumed placebo or CHO during exercise or
recovery (Chapter 5, 6, 7 and 8). However, an 18-h interval is sufficient for full recovery of
all immunoendocrine variables that were measured in this thesis from the impact of two
bouts of prolonged exercise (Chapter 8).
History
School
- Sport, Exercise and Health Sciences
Publication date
2004Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.403010Language
- en