Effects of exercise on emerging and traditional cardiovascular risk factors.
BACKGROUND
Common cardiovascular disease risk factors (e.g., insulin and aerobic fitness) are improved with exercise; however, few studies have addressed the potential for training to modify emerging cardiovascular disease risk factors such as homocysteine and high-sensitivity C-reactive protein.


METHODS
Sedentary adults (n = 324, 48.9 +/- 8.4 years) were randomized to four groups differing in training intensity (moderate = 45-55% or high = 65-75% of heart rate reserve) and frequency (low = 3-4, 30-min sessions/week or high = 5-7, 30 min-sessions/week).


RESULTS
Within-group changes in homocysteine, insulin, and aerobic fitness were significant (all P < 0.0125). Furthermore, homocysteine increased in the high-intensity-low-frequency (0.98 +/- 2.32 micromol/L) and high-intensity-high-frequency (0.93 +/- 2.56 micromol/L) groups, while aerobic fitness increased in the moderate-intensity-high-frequency (0.99 +/- 2.01 mL min(-1) kg(-1)) and high-intensity-high-frequency (1.77 +/- 2.97 mL min(-1) kg(-1)) groups (all P < 0.003). The change in aerobic fitness was greater in the high-intensity-high-frequency compared to the moderate-intensity-low-frequency group (1.77 +/- 2.97 vs. 0.36 +/- 2.10 mL min(-1) kg(-1), P = 0.0014) (effect size estimate = 0.60 mL min(-1) kg(-1)). The main effects for intensity, with respect to the change in insulin (effect size estimate = 0.46 microU/mL), and frequency, with respect to the change in aerobic fitness (effect size estimate = 0.38 mL min(-1) kg(-1)), were significant (P < 0.0125).


CONCLUSIONS
Although frequent bouts of higher intensity exercise were particularly effective in reducing fasting insulin and improving fitness, they resulted in slightly increased homocysteine levels.
Department of Epidemiology, Nutritional Sciences Program, University of Washington, Seattle, WA 98195, USA. duncag@u.washington.edu
Glen E
GE
Duncan
Michael G
MG
Perri
Stephen D
SD
Anton
Marian C
MC
Limacher
A Daniel
AD
Martin
David T
DT
Lowenthal
Erland
E
Arning
Teodoro
T
Bottiglieri
Peter W
PW
Stacpoole
D000328:Adult; D000886:Anthropometry; D002097:C-Reactive Protein / Q000032:analysis; D002318:Cardiovascular Diseases / Q000097:blood / Q000517:prevention & control*; D004032:Diet; D015444:Exercise; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D008019:Life Style; D008297:Male; D010101:Oxygen Consumption; D010349:Patient Compliance; D010809:Physical Fitness; D012307:Risk Factors
D007328:Insulin; D006710:Homocysteine; D002097:C-Reactive Protein