Pedometer-measured walking and risk factors for disease.

To the Editor: Research documenting the health benefits of exercise is convincing, but finding ways to encourage sedentary patients to become more active remains a challenge. Adherence to vigorous, structured exercise programs is particularly low. One generally inactive subgroup is older women, and postmenopausal women who do exercise tend to engage in moderate activity, specifically walking. The goal of this investigation was to document the relationship between daily walking volume (steps per day measured by a pedometer) and selected cardiovascular risk variables in postmenopausal women.

Eighty-eight postmenopausal women between the ages of 50 and 75 years volunteered for participation in this institutional-review-board-approved study at the University of Tennessee. Body composition was determined using a three-compartment model in which bone mineral content (GE Medical Systems, Lunar DPX-NT, Madison, WI) and total body density (air displacement plethysmography, Life Measurement Inc., Concord, CA) were measured. A 10 mL blood sample was obtained in the early morning hours when the subject was in a fasted and rested state. Samples were analyzed in a certified laboratory for total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (Trig), C-reactive protein (CRP), glucose (Glu), and hemoglobin AlC (AlC). Subjects subsequently wore a pedometer for 10 to 14 days, and an average daily step count was determined. Pearson correlations were used to explore the relationship between walking volume and cardiovascular risk variables (SPSS version 11 for Macintosh, Chicago, IL). Partial correlation coefficients were calculated to examine the relationship between walking volume and risk factors while controlling for the effect of body fat percentage (%BF). ANOVA was used to compare the HDL-C values among individuals in different physical activity categories.

The average age, %BF, and body mass index of participants was 61.0 [+ or -] 5.8 years, 40.2 [+ or -] 9.2%, and 27.8 [+ or -] 5.9 kg/[m.sup.2], respectively. Subjects ranged from very inactive (1,300 steps per day) to highly active (14,000 steps per day). The correlation between daily steps and %BF was -0.404 (P < 0.001). Walking volume was significantly related to HDL-C, TC to HDL-C ratio, and Trig (see Table).

Percent BF was significantly correlated with TC to HDL-C ratio and HDL-C (see Table). Glu was significantly related to both %BF (r = 0.217, P = 0.043) and steps (r = -0.289, P = 0.006), but there was no relationship between AlC and these variables. CRP was significantly related to %BF (r = 0.395, P < 0.001) but not steps (r = -0.106, P = 0.324). After controlling for %BF, daily steps remained significantly related to HDL-C (r = 0.247, P = 0.016), TC to HDL-C ratio (r = -0.284, P = 0.008), Trig (r = -0.239, P = 0.026), and Glu (r = -0.226, P = 0.035). The most active women, averaging approximately 8,000 steps per day, had a HDL-C of 71.6 [+ or -] 2.6 mg/dL. This was significantly higher (P < 0.05) than the HDL-C of women who walked approximately 5,000 steps per day (56.6 [+ or -] 2.7 mg/dL).

Walking is the most common physical activity chosen by women, (1) and the relationship between walking and health outcomes is particularly strong in this group. (2,3) This study provides additional evidence that daily walking is linked to important cardiovascular risk variables. Not surprisingly, these variables were also strongly associated with %BF. These data provide support for the important role that regular walking and weight control play in promoting cardiovascular health in postmenopausal women.

Pedometer-monitored programs are effective in helping sedentary individuals become more active. (4,5) This may be due to the fact that pedometer-monitored programs use goal setting and self-monitoring as reinforcement. There is evidence that the addition of a pedometer to a brief counseling session by a physician will lead to greater daily walking. (5) Given that walking is a generally safe form of aerobic exercise and yields important health benefits, physicians might consider prescribing pedometer-monitored programs for inactive patients.

Dixie L. Thompson, PHD

Emily M. Krumm, MS

Olivera L. Dessieux, MS

Pamela Andrews, MS

Center for Physical Activity and Health

Department of Exercise, Sport, and Leisure Studies

University of Tennessee

Knoxville, TN

References

1. Rafferty AP, Reeves MJ, McGee HB, et al. Physical activity patterns among walkers and compliance with public health recommendations. Med Sci Sports Exerc 2002;34:1255-1261.

2. Thompson DL, Rakow J, Perdue SM. Relationship between accumulated walking and body composition in middle-aged women. Med Sci Sports Exerc 2004;36:911-914.

3. Manson JE, Greenland P, LaCroix AZ, et al. Walking compared with vigorous exercise for the prevention of cardiovascular events in women. N Eng J Med 2002;347:716-725.

4. Hultquist CN, Albright C, Thompson DL. Comparison of walking recommendations in previously inactive women. Med Sci Sports Exerc 2005;37:676-683.

5. Stovitz SD, VanWormer JJ, Center BA, et al. Pedometers and brief physician counseling: increasing physical activity for patients seen at a family practice clinic. Med Sci Sports Exerc 2004;36:S241.

Table. Relationship between blood lipids and daily walking and body fat
percentage (a)

       TC             HDL-C          LDL-C          TC/HDL-C

Steps  -0.122(0.256)   0.358(0.001)  -0.188(0.079)  -0.373(<0.001)
%BF     0.085(0.430)  -0.338(0.001)   0.186(0.082)   0.314(0.003)

       Trig

Steps  -0.285(0.007)
%BF     0.173(0.108)

Values represent Pearson correlation coefficients with the significance
level in parentheses.
(a) TC, total cholesterol; HDL-C, high density lipoprotein cholesterol;
LDL-C, low density lipoprotein cholesterol; TC/HDL-C, the ratio of TC to
HDL-C; Trig, triglycerides; Steps, average daily steps; % BF, body fat
percentage.