Impact of three different types of exercise on components of the inflammatory response

It was hypothesized that muscle injury would be greater with eccentric than with all-out or prolonged exercise, and that immune changes might provide an indication that supplements the information provided by traditional mark ers such as creatine kinase (CK) or delayed-onset muscle soreness. Eight he althy males [mean (SE): age = 24.9 (2.3) years, maximum oxygen consumption ((V) over dot O-2max) = 43.0 (3.1) ml . kg(-1) . min(-1)] were each assigne d to four experimental conditions, one at a time, using a randomized-block design: 5 min of cycle ergometer exercise at 90% (V) over dot O-2max (AO), a standard circuit-training routine (CT), 2 h cycle ergometer exercise at 6 0% (V) over dot O-2max (Long), or remained seated for 5 h. Blood samples we re analyzed for CK, natural killer (NK) cell counts (CD3(-)/CD16(+)56(+)), cytolytic activity and plasma levels of the cytokines interleukin (IL)-6, I L-10, and tissue necrosis factor alpha (TNF-alpha). CK levels were only ele vated significantly 72 h following CT. NK cell counts increased significant ly during all three types of exercise, but returned to pre-exercise baselin e values within 3 h of recovery. Cytolytic activity per NK cell was not sig nificantly modified by any type of exercise. Prolonged exercise induced sig nificant increases in plasma IL-6 and TNF-alpha. We conclude that the lack of correlation between traditional markers of muscle injury (plasma CK conc entrations and muscle soreness rankings) and immune markers of the inflamma tory response suggests that, for the types and intensities of exercise exam ined in this study, the exercise-induced inflammatory response is modified by humoral and cardiovascular correlates of exercise.