Craig E. Broeder

The Effects of Acute Exercise on Neutrophils and Plasma Oxidative Stress

PURPOSE To investigate the influence of intensity versus total energy expenditure on neutrophilia and blood oxidative stress to acute exercise. METHODS Nine males (18-30 yr) completed one maximal (Max) and three submaximal exercise sessions: 1) 45 min at 10% above (LT+) lactate threshold (LT), 2) 45 min at 10% below (LT-) LT, and 3) 10% below LT until caloric expenditure equaled the 10%+ trial (LT-kcal). Blood was sampled before (PRE), immediately (POST), 1 h, and 2 h after exercise to measure neutrophils, myeloperoxidase, superoxide (O(2)-), neutrophil activation (O(2)-/neutrophils), ascorbic acid, uric acid, malondialdehyde, and lipid hydroperoxides. RESULTS Intensity-dependent neutrophilia occurred POST exercise with significant increases (P <or= 0.05) after Max and LT+. A second neutrophilia wave occurred 2 h postexercise. Superoxide was elevated POST (Max) and 2 h post (Max and LT+). In contrast, O(2)-/neutrophils was increased at 2 h only (Max and LT+). These data indicate that immediately postexercise, total neutrophil number rather than activation best represents neutrophil-generated reactive species within blood. POST Max, ascorbic acid and uric acid were decreased indicating a blood oxidative stress occurred. Alternately, total energy expenditure was not related to any marker of neutrophilia or oxidative stress. CONCLUSION Exercise intensity plays a major role in postexercise blood oxidative stress, whereas total exercise energy expenditure does not. Further, neutrophils recruited into circulation during exercise may impose a threshold dependent oxidative stress in blood plasma after exercise.

Assessing body composition before and after resistance or endurance training

This studys purpose was to determine the validity of near-infrared interactance (NIR) and bioelectric impedance (BIA) in tracking changes in body composition over 12 wk of either a high intensity endurance (ET) or resistance (RT) training program in nondieting weight-stable untrained males. Prior to and following the control or training period, each subject completed a series of body composition analyses including hydrostatic weighing (HW) with a measurement of residual volume: anthropometric measurements including height, weight, skinfold, and girth: BIA measurement: and NIR measurements. Based on the HW results, there were no significant body composition changes in the control group. For the ET group, a significant decline in relative body fat resulted from a reduction in fat weight (FW) with no change in fat-free weight (FFW). In the RT group, both a significant decline in FW and an increase in FFW contributed to this groups decline in relative body fat. Tracking changes in relative body fat, FW, and FFW, skinfolds agree reasonably well with HW in all groups while BIA and NIR did not always track body composition changes well. For example, SF and BIA were significantly correlated with the changes in FFW (HW = +4.1%, SF = +4.5%. BIA = +3.1%. NIR = -0.7%) observed in the RT group compared to HW (SF: r-value = 0.45, SEE = 2.5; BIA: r = 0.33, SEE = 3.4) while the NIR measurements were nonsignificant (r = 0.09, SEE = 5.0). Interestingly, NIR underestimated the gain in FFW in the resistance trained group while BIA underestimated the changes in relative body fat. FW, and FFW in the endurance trained group. Based on these results, BIA and NIR appear not to be appropriate measurement tools for tracking body composition changes in endurance and resistance training individuals respectively.