A Systematic Review of the Acute Effects of Exercise on Immune and Inflammatory Indices in Untrained Adults
Brown et al. Sports Medicine - Open
A Systematic Review of the Acute Effects of Exercise on Immune and Inflammatory Indices in Untrained Adults
William M. C. Brown 0
Gareth W. Davison 0
Conor M. McClean 0
Marie H. Murphy 0
0 Sport and Exercise Sciences Research Institute, Ulster University , Jordanstown BT37 0QB , Northern Ireland
Background: Cardiovascular disease (CVD) is the leading cause of global mortality. Although the incidence may be reduced with regular exercise, the health benefits of a single bout of exercise on selected CVD risk factors are not well understood. The primary objective of this review is to consider the transient effects of exercise on immune (neutrophil count) and inflammatory (interleukin-6 [IL-6], C-reactive protein [CRP]) markers in untrained adults. Methods: MEDLINE, EMBASE, CINAHL, Sports Discus and Cochrane were searched for relevant studies published from January 1946 to May 2013. Randomised controlled or crossover studies which measured any of these parameters in untrained but otherwise healthy participants in the 48 h following about of exercise, less than 1 h in duration were included. Results: Ten studies met the inclusion criteria. The results indicate a single bout of aerobic or resistance exercise of moderate to high intensity promotes an increase in IL-6 (145 %) and neutrophil counts (51 %). It appears that 30-60 min of moderate to high intensity exercise is necessary to elicit such changes although variables such as the mode, intensity and pattern of exercise also affect the response. The acute response of CRP within the included studies is equivocal. Conclusions: Although responses to CRP are inconsistent, a single bout of exercise can increase the activity of both circulating IL-6 and neutrophil counts in untrained adults. These immune and inflammatory responses to a single bout of exercise may be linked to a range of health benefits.
-
IL-6 and neutrophil counts increase in response to a
bout of aerobic or resistance exercise of moderate to
high intensity lasting 30–60 min in duration.
The acute effect of a single bout of exercise on
C-reactive protein is equivocal, and further research
is warranted.
Transient changes in immune and inflammatory
markers evoked by a single bout may be linked to
the health benefits of regular exercise.
Background
Physical inactivity is an established independent risk
factor for cardiovascular disease (CVD) [
36, 71
]. CVD
is the major cause of mortality within developed
nations and at the forefront of this disease pathology is
chronic systemic low-grade inflammation [29].
Characteristically, this state of inflammation permits the
secretion of pro-inflammatory cytokines particularly IL-6,
tumour necrosis factor (TNF)-α and CRP which are
actively involved in insulin resistance and hyperglycaemia
[
74
]. A likely downstream effect of hyperglycaemia is
endothelial dysfunction which is associated with a
reduction in the bioavailability of vasodilators such as
nitric oxide (NO) [
1, 13
] and is often regarded as an
initial step in the development of CVD [62]. Such
detrimental effects inhibit the key functions of endothelial
cells, namely modulating vascular tone, and over time
may lead to cardiovascular complications [
6
].
Achieving current physical activity recommendations
which encourages daily exercise of at least moderate
intensity and accumulating 150 min per week may be an
effective strategy to reduce the risk of CVD and other
diseases [
18
]. Regular physical activity promotes many
health benefits including improved glucose disposal,
reduced blood pressure and favourable changes in the
blood lipid profile, all of which have beneficial effects on
CVD risk [
14, 46
]. At any stage, individuals adhering to
the physical activity guidelines are likely to be no more
than 48 h from their last bout of physical activity.
Therefore, the beneficial adaptations derived from physical
activity may be in part, attributed to the short-term or
acute changes that occur in the minutes, hours and days
following a bout of activity [27]. Thus, a single bout of
exercise appears to act as a stimulus for changes which
cumulatively are regarded as exercise adaptations.
Physical activity involves the contraction of skeletal
muscles [
25
] which may promote the synthesis and
secretion of anti-inflammatory cytokines and peptides
from myotubes commonly termed as ‘myokines’ [
56
].
Research to date indicates that a single bout of moderate
to vigorous intensity aerobic exercise lasting 30–60 min in
duration stimulates muscle-derived IL-6 [
26, 35, 48, 49,
65, 68
]. However, findings in this area are equivocal with
others reporting no transient changes following a bout of
exercise [
19, 21, 43, 47
]. The differing outcomes may be
attributed to methodological issues, such as exercise
intensity or duration or indeed the individual characteristics
of the sample population particularly training status.
Elevated plasma concentrations of (...truncated)