Table 1.
Characteristics (mean±SD) of runners by reported distance run per day.
Table 2.
Regression slopes (±SE) for body mass index (BMI) and body circumferences vs. reported obesity status of the subject's mother and father (kg/m2 or cm per increment) adjusted for age, education, and alcohol intake and stratified by the subject's running distance.
Table 3.
Multivariate regression to determine the linear combinations of reported obesity of the mother and father that best predicts body mass index (BMI) and body circumferences in runners who averaged <3 km/day.
Figure 1.
Reduced impact of parental adiposity as a risk factor for excess body weight with greater distance run.
The parental adiposity index is the linear combination of the mothers' and fathers' adiposities that most strongly predicted the runners' adiposity within the <3 km/day group. In the analyses, the coefficient (slope) for the <3 km/day category is always one because it was the category of runners used to define the index. Significance levels above each bar refer to the significance of the parent-offspring relationship within each distance category. The inheritance x exercise interaction tests whether the parent-offspring relationships differed by the offsprings' running distance. When the coefficients (slopes) for other running categories (3–6, 6–9, ≥9 km/day) are less than one, this means that exercise has attenuated the parental contribution. Specifically, the coefficient estimates the reduction in the effect of the parents' adiposities on their offsprings' BMIs and body circumferences.
Figure 2.
Effect of parental adiposity on runners' pre-exercise BMI, waist circumference, and chest circumference, showing no significant association with exercise.
The inheritance x exercise interaction tests whether the parent-offspring relationships differed by the offsprings' running distance. Parental adiposity was strongly related to pre-exercise BMI in male runners (P<10−15 all categories) and female runners who currently ran <3 (P<10−15), 3–6 and (P<10−15), 6–9 (P<10−11), and >9 km/day (P<10−7), pre-exercise waist circumference in male and female runners who currently ran <3 (P<10−15 and P<10−9, respectively), 3–6 (P<10−15 and P<10−10, respectively), 6–9 (P<10−13 and P<0.0001, respectively), and ≥9 km/day (P<10−15 and P = 0.006, respectively), and pre-exercise chest circumference in male and female runners who currently ran <3 (P<10−15 and P = 0.0003, respectively), 3–6 (P<10−15 and P<10−6, respectively), 6–9 (P<10−6 and P = 0.03, respectively), and ≥9 km/day (P<10−12 and P<10−4, respectively). The analyses are restricted to the 96.7% of men and 94.3% of women who provided a weight for when they had first started running 12 or more miles per week.