Using data from 12 days of detailed physical activity records (PA records), we analyzed the physical activity patterns of 141 African American and Native American women, ages 40 and older, enrolled in the Cross-Cultural Activity Participation Study. PA records were completed every other month for three consecutive 4-day periods. The proportion of women who met the 1993 Centers for Disease Control and Prevention and the American College of Sports Medicine recommendation to accumulate at least 30 minutes of moderate intensity activity during most days of the week (at least 3 days of the 4-day periods) ranged from 63% to 70%. Nearly one third of women met the recommendation for more than one 4-day period. On days when subjects accumulated at least 30 minutes of moderate activity, time spent in moderate activity was 112 minutes/day. Most women performed household chores (95%, median = 24 minutes/day), walking for exercise (87%, median = 30 minutes/day), occupational (65%, median = 37 minutes/day), child care (53%, median = 32 minutes/day), and lawn and garden activities (51%, median = 43 minutes/day). Fewer than 25% reported conditioning and sports activities. In general, more Native Americans than African Americans were active in moderate activities. In conclusion, definitions used to characterize regular physical activity should be consistent among studies, and physical activity surveys among women should include occupation-related and home-related activities.

The purpose of this investigation was to determine the effects of transdermal estradiol (E2) replacement on substrate utilization during exercise. Amenorrheic females (N = 6) performed three exercise trials following 72 h of placebo (C 72) and 72 and 144 h of medicated transdermal estradiol (E2) treatment (E2 72 and E2 144). Exercise involved 90 min of treadmill running at 65% VO2max followed by timed exercise to exhaustion at 85% VO2max. Resting blood samples were obtained for glucose, insulin, free fatty acids (FFA), and E2. Exercise blood samples were obtained for E2, lactate, epinephrine, and norepinephrine. Rates of appearance and disposal were calculated for glucose and glycerol using a primed, continuous infusion of [6,6-2H] glucose and [2H5] glycerol. Medicated transdermal placement increased E2 significantly at rest, before exercise (35.03 +/- 12.3, 69.5 +/- 20.1, and 73.1 +/- 31.6 pg.mL-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Resting FFA increased significantly following E2 treatment (0.28 +/- 0.16, 0.41 +/- 0.27, and 0.40 +/- 0.21 mmol.L-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Glucose Ra was significantly decreased during exercise as a result of E2 replacement (21.9 +/- 7.7, 18.9 +/- 6.2, and 18.9 +/- 5.6 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Average glucose Rd also decreased during exercise as a result of E2 replacement (21.3 +/- 7.8, 18.5 +/- 6.4, and 18.6 +/- 5.8 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). However, the estimated relative contribution of plasma glucose and muscle glycogen to total carbohydrate oxidation was similar among the trials. Epinephrine values were significantly lower late in exercise during the E2 72 and E2 144 trials, compared with the C 72 trial (P < 0.05). These results indicate that elevated E2 levels can alter glucose metabolism at rest and during moderate intensity exercise as a result of decreased gluconeogenesis, epinephrine secretion, and/or glucose transport.

449 Physical activity (PA) has a beneficial e ffect in reducing plasma insulin levels among people with and without type 2 diabetes (1-3). Much of the evidence for this effect is from estimates of total daily PA and participation in vigoro u s PA. Few studies have re p o rted an effect of moderate-intensity PA on insulin levels. In the Insulin Resistance Athero s c l e ro s i s S t u d y, Mayer-Davis et al. (2) showed a significant association between moderate-and v i g o rous-intensity PA and insulin sensitivity among people with and without type 2 diabetes (P 0.05). In the San Luis Va l l e y S t u d y, Regensteiner et al. (3) showed an inverse association between PA and fasting insulin levels (P 0 . 0 5 ) .The mechanisms by which PA decre a s e s insulin resistance and hyperinsulinemia are not yet fully understood. PA directly re d u c e s insulin resistance and hyperinsulinemia by i n c reasing the number and activity of glucose transporters (especially the GLUT4 isof o rm), in both muscle and adipose tissue (1,4). In addition, PA may indirectly re d u c e insulin resistance and hyperinsulinemia by p romoting fat loss and pre s e rvation of lean body mass (1).W h e reas most studies generally show that vigorous PA may reduce insulin concentrations, these results are not dire c t l y applicable to most women who do not re gularly perf o rm such vigorous PA. In 1995, the Centers for Disease Control and Prevention (CDC) and the American College of S p o rts Medicine (ACSM) released a statement recommending that all U.S. adults accumulate at least 30 min of moderateintensity PA on most, if not all, days of the week (5). This moderate-intensity re c o mmendation differs from previous re c o mmendations suggesting that adults should e x e rcise vigorously for at least 20 min thre e times per week (6). Few studies have examined the association between moderateintensity PA, at levels recommended by the CDC and ACSM, and fasting insulin levels.It is important to examine the association between PA and fasting insulin by levels of central obesity and card i o re s p i r a t o ry fitness. Centrally obese individuals are at i n c reased risk for insulin resistance and may be more likely to decrease their risk t h rough increased PA (7), and moderateintensity PA is relatively more strenuous for an individual with a low card i o re s p i r a t o ry fitness level than an individual with a high c a rd i o re s p i r a t o ry fitness level. The purpose of this study was to determine the association between moderate-intensity PA and fasting insulin levels and to examine possible diff e rences in this association by r a c e / e t h n i c i t y, central obesity, and card i o re s p i r a t o ry fitness level. MET intensity, the associated metabolic rate for a specific activity divided by a standard resting metabolic rate; MET-min, the product of the minutes for each activity times the MET intensity level; PA, physical activity.A table elsewhere in this issue shows conventional and Système International (SI) units and conversion...