A Systematic Review of the Acute Effects of Exercise on Immune and Inflammatory Indices in Untrained Adults

Sports Medicine - Open, Oct 2015

William M. C. Brown, Gareth W. Davison, Conor M. McClean, Marie H. Murphy

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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)


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William M. C. Brown, Gareth W. Davison, Conor M. McClean, Marie H. Murphy. A Systematic Review of the Acute Effects of Exercise on Immune and Inflammatory Indices in Untrained Adults, Sports Medicine - Open, 2015, pp. 35, Volume 1, Issue 1, DOI: 10.1186/s40798-015-0032-x