Abstract
Markers of chronic inflammation increase with aging, and are associated with cardiovascular disease prevalence and mortality. Increases in fitness with exercise training have been associated with lower circulating concentrations of cytokines known to have pro-inflammatory actions (such as interleukin-6 [IL-6]) and higher circulating concentrations of anti-inflammatory cytokines (interleukin-10 [IL-10]). However, the effect of cardiorespiratory fitness on acute cytokine responses to a single bout of exercise in healthy older individuals is unknown. We compared the response of plasma cytokines IL-6, tumor necrosis factor-alpha (TNF-α) and IL-10 to a bout of moderate-intensity continuous and higher-intensity interval exercise between older individuals with higher and lower levels of cardiorespiratory fitness. Sixteen lower-fit (VO2peak: 22.6±2.8 mL.kg−1.min−1) and fourteen higher-fit participants (VO2peak: 37.4±5.9 mL.kg−1.min−1) completed three 24 min experimental protocols in a randomized order: (1) moderate-intensity continuous exercise (40% of peak power output [PPO]); (2) higher-intensity interval exercise (12 × 1 min intervals at 70% PPO separated by 1 min periods at 10% PPO); or (3) non-exercise control. Plasma cytokines were measured at rest, immediately after, and during 90 min of recovery following exercise or control. Plasma IL-6 concentrations at baseline were greater in the higher-fit compared to the lower-fit group (P = 0.02), with no difference in plasma IL-10 or TNF-α concentrations at baseline between groups. Plasma IL-6 and IL-10 concentrations in both groups increased immediately after all protocols (IL-6: P = 0.02, IL-10: P < 0.01). However, there was no difference in the IL-6 and IL-10 response between the exercise and non-exercise (control) protocols. After all protocols, no changes in plasma TNF-α concentrations were observed in either the higher- or lower-fit groups. In this study, basal concentrations of circulating IL-6 were elevated in older individuals with higher levels of cardiorespiratory fitness. However, changes in plasma cytokine concentrations after exercise were not different to changes after non-exercise control in both the lower- and higher-fit groups.
Highlights
Chronic, low-grade inflammation is a common feature of various age-related chronic diseases (Himmerich et al, 2006)
In response to a short bout of exercise, acute increases in IL-6 have been proposed to suppress pro-inflammatory TNFα (Starkie et al, 2003), and up-regulate anti-inflammatory cytokines such as IL-10 (Steensberg et al, 2003; Lira et al, 2009), creating an anti-inflammatory milieu for several hours after the cessation of exercise (Mendham et al, 2015). While this response is well established in young people, the response in older adults is more varied, with reports that the skeletal muscle (Hamada et al, 2005) and circulating (Reihmane et al, 2013, 2016) cytokine responses to a single bout of exercise may be supressed compared with those observed in young participants
Our findings suggest that a single bout of moderate-intensity continuous or higher-intensity interval cycling exercise does not elicit a measurable cytokine response in healthy older adults, and these responses were similar in older adults with higher or lower levels of cardiorespiratory fitness
Summary
Low-grade inflammation is a common feature of various age-related chronic diseases (Himmerich et al, 2006). Regular exercise facilitates the creation of an anti-inflammatory environment (Petersen and Pedersen, 2005), leading to reduced basal inflammatory-, and increased anti-inflammatory, cytokine concentrations in both younger and older adults (Monzillo et al, 2003; Goldhammer et al, 2005; Santos et al, 2012) These long-term changes in circulating cytokines are believed to be mediated by the repeated acute inflammatory, and subsequent anti-inflammatory cytokine responses during recovery from single bouts of exercise (Reihmane and Dela, 2014). In response to a short bout of exercise, acute increases in IL-6 have been proposed to suppress pro-inflammatory TNFα (Starkie et al, 2003), and up-regulate anti-inflammatory cytokines such as IL-10 (Steensberg et al, 2003; Lira et al, 2009), creating an anti-inflammatory milieu for several hours after the cessation of exercise (Mendham et al, 2015). While this response is well established in young people, the response in older adults is more varied, with reports that the skeletal muscle (Hamada et al, 2005) and circulating (Reihmane et al, 2013, 2016) cytokine responses to a single bout of exercise may be supressed compared with those observed in young participants
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