THE ASSOCIATION BETWEEN ATHLETIC TRAINING TIME AND THE SAGITTAL CURVATURE OF THE IMMATURE SPINE
Participants: E. M. Wojtys, J. A. Ashton-Miller, L. J. Huston, P. Moga
Keywords: spine, athletic activity, kyphosis
Introduction
Athletic training and conditioning is an integral component of sports participation. In order to reach the elite levels of competition, sustained training often begins during adolescence. Since the demands of such preparation can be quite high, and the physical effects of such training are in many circumstances unknown, the goal of this investigation was to examine the association between cumulated hours of athletic training and the magnitude of the sagittal curvature of the immature spine.
Materials and Methods
A sample of 2,270 children (407 females) between 8 and 18 years were studied. A non-contact optical rasterstereographic method was used to measure the mid-sagittal surface of the back in the upright standing position in order to quantify the angles of thoracic kyphosis and lumbar lordosis. These data were then correlated with self-reported hours of training using an interviewer and questionnaire. The possible effects of age, gender, sport, and upper and lower body weight training were investigated. Both internal and external validation studies were performed to determine the questionnaire’s reliability.
Results
A significant difference was found in the thoracic and lumbar sagittal curves when adolescents were stratified by their primary sport (Table 1). Non-athletic controls exhibited the smallest thoracic and lumbar curves. Larger angles of thoracic kyphosis and lumbar lordosis were associated with greater cumulative training times (hours/year; p<0.001). For example, the thoracic kyphosis averaged 5° greater in those training more than 400 hrs/year than in those training less than 100 hrs/year. Age, gender, and weight training did not appear to affect the degree of curvature.
Table 1. Mean (SD) Thoracic Kyphosis and Lumbar Lordosis Angles Stratified by Sport
| Sport | Thoracic Angle (°) | Lumbar Angle (°) |
| Control Group | 16.1 (10.4) | 17.6 (15.6) |
| Track | 29.5 (10.1)* | 33.5 (17.0)* |
| Volleyball | 29.9 (13.9)* | 37.4 (21.7)* |
| Hockey | 38.1 (11.7)** | 44.5 (14.8)*† |
| Wrestling | 39.5 (12.2)** | 42.4 (16.2)*† |
| Football | 39.8 (16.2)** | 46.2 (20.2)*† |
| Swimming | 40.8 (13.0)** | 44.0 (16.5)*† |
| Gymnastics | 42.4 (13.4)** | 52.1 (16.7)*†^ |
| Total | 38.5 (13.6)** | 42.4 (17.5)*† |
*: vs. the control group (p<0.0001)
**: vs. Track and Volleyball (p<0.001); vs. the control group (p<0.0001)
†: vs. Track and Volleyball (p<0.05)
^: vs. Hockey, Swimming, Wrestling (p<0.02)
Conclusions
The results suggest an association between exposure to athletic training and increased thoracic kyphosis and lumbar lordosis angles, as measured using back surface profiles. These alterations might involve changes in disc height and vertebral body shape in the immature spines (Stokes, 1998). The mechanisms underlying the development of these increased sagittal curves remain unknown.