Previous studies have shown that intervertebral discs compress under axial loading, yet few studies have examined the relationship between disc age and compressibility. The purpose of this study was to determine if the amount of vertebral column height (VCH) loss induced by running was significantly different between two age groups, 17 males ages 20-27 years and 14 males ages 50-57 years, who could comfortably run 6 miles. The subjects had no previous or current back pathologies. Within 1.5 hours of rising in the morning, each subject's VCH was measured from spinous processes C7 to S2. Immediately following the measurement, each subject ran a predetermined, paved, 6-mile course at a comfortable pace. Within minutes after completing the run, each subject was again measured for VCH. Paired t tests revealed significant decreases in VCH after the run in both groups. An independent t test showed no significant differences between the respective age groups in terms of postrun VCH decreases. Although no significant differences were noted between groups, this study has demonstrated that both age groups experienced significant decreases in VCH after a 6-mile run. These findings have implications for physical therapy for younger and older male patients who may have back pathologies and require an exercise program. Patients may be advised to limit running due to possible exacerbation of back symptoms.