Physical loading associated with certain activities such as resistance training and running has been shown to have an osteogenic effect. However, endurance sports such as Cross Country (XC) with higher volumes of smaller, repetitive stresses may have a deleterious effect on bone mineral density (BMD) and content (BMC). Whole body vibration (WBV) has been shown to be an effective means of increasing bone mineral accumulation in certain populations, typically older females. PURPOSE: The purpose of this study was to investigate whether WBV was an effective means of increasing BMD and BMC in Division I XC/distance runners during their competitive indoor and outdoor track season. METHODS: Ten D-1XC/distance runners (5 males, 4 females) were randomly assigned to either a control group or an experimental group. Athletes in the experimental group performed 3 sets of 30 second vibration treatments at 30 Hz and an amplitude of 5 – 7 mm five days a week prior to their afternoon training sessions for 4 months. Mondays, Wednesdays, and Fridays the experimental group stood on the vibration unit (130° knee angle) while Tuesdays and Thursdays they supported themselves in the pushup position with arms locked. DXA (dual energy x-ray absorptiometry) was used to measure BMC(g) and BMD(g/cm2). Sites measured by DXA (Lunar Prodigy, GE Health Care Systems) included in the total body, both hips (total, femoral neck, trochanter, shaft and Ward's triangle area), the lumbar vertebrae and both distal forearms (radius UD, Ulna UD, radius 33%, ulna 33%, total radius and total ulna). From the total body measurements the following sites were separately examined: left and right arm, left and right leg, the spine and the skull. Total training miles from 4 months prior to the start of the study through the completion of the study were collected and compared. Statistically, the pre and post test data were compared using a two-tailed t-test. RESULTS: There were no significant differences in BMD and BMC at all sites measured between the groups prior to the start of the vibration protocol. Reported running volume was not significantly different between groups in the 4 months prior to both the pre and post DXA measures (P = 0.67). Neither BMD nor BMC were significantly different in either the control or the vibration group between the pre and post DXA measurements in any of the sites measured. CONCLUSION: The results suggest that 4 months WBV does not have an effect on BMD or BMC. This may be due to the duration of the study, the frequency and or amplitude used, varying upper and lower body stress through the week, or nutritional factors not measured. PRACTICAL APPLICATION: These results suggest that whole body vibration utilizing the current protocol is not a viable method for increasing bone mineral density and content of D-1 XC Runners.
1Kinesiology Leisure & Sport Science, East Tennessee State University, Johnson City, TN; 2Osteoporosis Center, ETSU Quillen College of Medicine, Johnson City, TN; and 3Center of Excellence for Sport Science and Coach Education, East Tennessee State University, Johnson City, TN