Acute Exercise and Oxidative Stress: CrossFit™ vs. Treadmill Bout

CrossFit (TM), a popular high-intensity training modality, has been the subject of scrutiny, with concerns of elevated risk of injury and health. Despite these concerns empirical evidence regarding physiologic stresses including acute oxidative stress is lacking. Therefore, the purpose of this investigation was to examine the acute redox response to a CrossFit (TM) bout. Furthermore, these findings were compared to a high-intensity treadmill bout as a point of reference. Ten males 26.4 +/- 2.7 yrs having three or more months of CrossFit (TM) experience participated in the present study. Blood plasma was collected at four time points: Pre-exercise (PRE), immediately-post-exercise (IPE), 1 hr-post (1-HP) and 2 hr-post (2-HP), to examine oxidative damage and antioxidant capacity. Regarding plasma oxidative damage, CrossFit (TM) and Treadmill elicited a time-dependent increase of lipid peroxides 1-HP (CrossFit (TM)=+143%, Treadmill=+115%) and 2-HP (CrossFit (TM) =+256%, Treadmill+167%). Protein Carbonyls were increased IPE in CF only (+5%), while a time-dependent decrease occurred 1-HP (CrossFit (TM)=-16%, Treadmill=-8%) and 2-HP (CF=-16%, TM=-1%) compared to IPE. Regarding antioxidant capacity, Ferric Reducing Antioxidant Power also demonstrated a time-dependent increase within CrossFit (TM) and Treadmill: IPE (CrossFit (TM)=+25%, Treadmill=+17%), 1-HP (CrossFit (TM)=+26%, Treadmill=+4.8%), 2-HP (CrossFit (TM)=+20%, Treadmill=+12%). Total Enzymatic Antioxidant Capacity showed a time-dependent decrease in IPE (CrossFit (TM)=-10%, Treadmill=-12%), 1-HP (CrossFit (TM)=-12%, Treadmill=-6%), 2-HP (CrossFit (TM)=-7%, Treadmill=11%). No trial-dependent differences were observed in any biomarker of oxidative stress. The CrossFit (TM) bout elicited an acute blood oxidative stress response comparable to a traditional bout of high-intensity treadmill running. Results also confirm that exercise intensity and the time course of exercise recovery influence oxidative responses.