Effect of different doses of aerobic exercise on total white blood cell (WBC) and WBC subfraction number in postmenopausal women: results from DREW

Abstract

Background: Elevated total white blood cell (WBC) count is associated with an increased risk of coronary heart disease and death. Aerobic exercise is associated with lower total WBC, neutrophil, and monocyte counts. However, no studies have evaluated the effect of the amount of aerobic exercise (dose) on total WBC and WBC subfraction counts.

Purpose: To examine the effects of 3 different doses of aerobic exercise on changes in total WBC and WBC subfraction counts and independent effects of changes in fitness, adiposity, markers of inflammation (IL-6, TNF-α, C-reactive protein), fasting glucose metabolism, and adiponectin.

Methods: Data from 390 sedentary, overweight/obese postmenopausal women from the DREW study were used in these analyses. Women were randomized to a non-exercise control group or one of 3 exercise groups: energy expenditure of 4, 8, or 12 kcal kg(-1)⋅week(-1) (KKW) for 6 months at an intensity of 50% VO2peak.

Results: A dose-dependent decrease in total WBC counts (trend P = 0.002) was observed with a significant decrease in the 12KKW group (-163.1±140.0 cells/µL; mean±95%CI) compared with the control (138.6±144.7 cells/µL). A similar response was seen in the neutrophil subfraction (trend P = 0.001) with a significant decrease in the 12KKW group (-152.6±115.1 cells/µL) compared with both the control and 4KKW groups (96.4±119.0 and 21.9±95.3 cells/µL, respectively) and in the 8KKW group (-102.4±125.0 cells/µL) compared with the control. When divided into high/low baseline WBC categories (median split), a dose-dependent decrease in both total WBCs (P = 0.003) and neutrophils (P<0.001) was observed in women with high baseline WBC counts. The effects of exercise dose on total WBC and neutrophil counts persisted after accounting for significant independent effects of change in waist circumference and IL-6.

Conclusion: Aerobic exercise training reduces total WBC and neutrophil counts, in a dose-dependent manner, in overweight/obese postmenopausal women and is especially beneficial for those with systemic low grade inflammation.

Clinical trials identifier: NCT00011193.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1. CONSORT schematic of study participation.

Figure 2. Change (Δ) in total WBC and neutrophil counts by exercise group (control, 4, 8, and 12 kcal kg−1 min−1; KKW) and high/low baseline WBC counts.

Interaction  =  group x high/low WBC category; trend high and low are from general linear model across intervention groups separately for each high/low baseline WBC category. The participant numbers (n) in the high baseline total WBC groups were 41, 71, 41, and 43 and low baseline total WBC groups were 45, 63, 37, and 49 for Control, 4, 8, and 12 KKW, respectively. The participant numbers (n) in the high baseline neutrophil groups were 40, 71, 42, and 42 and low baseline neutrophil groups were 46, 63, 36, and 50 for Control, 4, 8, and 12 KKW, respectively. * Significantly different between high/low baseline WBC categories within an exercise group.