C-REACTIVE PROTEIN AND EXERCISE INTENSITY IN AFRICAN AMERICANS

Racial health disparities have been shown in Cardiovascular Disease (CVD) with African Americans having a substantially greater risk compared to Caucasian Americans. One potential factor explaining racial differences in CVD may be increased levels of systemic inflammation in African Americans compared to Caucasians. Epidemiological studies have shown that CRP (a marker of systemic inflammation) is an independent risk factor for cardiovascular mortality6,7, and is higher in African Americans compared to Caucasians. In addition to the elevated CRP levels, African Americans have increased levels of obesity and lower cardiorespiratory fitness compared to Caucasians. Although results have been inconsistent in studies related to exercise interventions to improve CRP levels, many studies have had primarily Caucasian participants and/or have used different intensities of aerobic training. PURPOSE: The purpose of the present study was to determine the effects of moderate and high intensity aerobic exercise training on CRP in obese African-American men and women. METHODS: The present study was a randomized-controlled trial of 60 obese and overweight African American men and women (body mass index of 25-45 kg/m2), 35-65 years. Participants were randomized to the moderate intensity (MOD-INT; n = 20), high intensity (HIGH-INT; n = 20), or non-exercise control group (n = 20) for a 24-week intervention. The moderate intensity group participated in aerobic exercise at 50% of their VO2 max, and the high intensity group participated in aerobic exercise at 75% of their VO2 max. Participants completed a 12-hour fasted blood draw at the East Carolina Heart Institute. A venous blood sample of a total of 21 mL of blood was drawn by the study nurse pre and post exercise intervention. Blood samples were sent to a clinical laboratory (LabCorp Inc., Burlington, NC) for a complete analysis of metabolic, lipid, insulin level measures, CRP, and blood chemistries. The serum separator tube was sent to LabCorp for measurement of C-reactive protein. RESULTS: There were 11 participants in the control group, 10 participants in the moderate intensity exercise group, and 13 in the high intensity exercise group. There were no significant differences between the randomization groups for age, gender, weight, BMI, waist circumference, body fat percentage, glucose, insulin, and CRP (p> 0.05). We did not observe significant change in CRP levels among study groups in the MOD or the HIT group compared to the CON in obese African-American adults (p=1.00). The association between exercisers and change in CRP and fat-mass approached a significant change (r=-0.379, p=0.07). The HIGH-INT group had a larger increase in VO2 max (ml·kg·min; L/min) (p[less-than]0.05) compared to the CON group. Also, there was a significant relationship between the CON group and MOD intensity group in estimated METs (p[less-than]0.01). Data for changes in clinical risk factors between participants based on change in CRP are shown in Table 2. There were no significant changes found in CRP for any clinical risk factors between non-responders and responders (p>0.05). CONCLUSION: In conclusion, we observed that neither moderate or high intensity aerobic decreased systemic inflammation levels in obese African Americans. Secondly, CRP was not improved with a change in fat-mass in exercisers. Future research could allow for the analysis of both Caucasian and African Americans, allowing for a more direct comparison between the two races for the intervention variables measured. Also, it could entail an interval training aerobic group, as well as a resistance training exercise group to elucidate further comparisons in intervention variables. Lastly, future studies may want to combine dietary and exercise to potentially lower CRP to a greater extent than exercise alone