Influencia de la práctica del tenis sobre las curvaturas sagitales del raquis y la extensibilidad isquiosural en deportistas adolescentes

Abstract

INTRODUCTION A high volume of training in specific postures and repetitive movements could generate specific adaptations. For this reason, several studies have assessed the spinal curvatures in different sport disciplines, finding specific morphological spine adaptations depending on the sport practiced. However, the influence of tennis practice has not been sufficiently analyzed. Furthermore, few studies have examined the acute influence of training or competition. OBJECTIVE To determine the sagittal thoracic and lumbar curvatures as well as pelvic tilt of tennis players in several positions (standing, sitting and during trunk flexion and extension). Furthermore, the hamstring extensibility was evaluated with angular and linear tests. All measures were taken before and after a tennis training session. METHODS Forty adolescent tennis players from 14 to 18 years old (mean age: 16.35 ± 1.82 years) participated in this study. The inclusion criteria were: having played tennis for at least four years. The exclusion criteria were: a history of spinal and hamstring surgery, a medically diagnosed spinal disorder or having hamstring or spinal pain at the moment of the assessment. PROCEDURES Sagittal spinal curvatures and pelvic tilt were assessed in standing position, standing in self-correction, maximum trunk extension in standing, slumped sitting, maximum trunk flexion in seated position and prone lying. Hamstring extensibility was measured by the sit-and-reach test, toe-touch test and straight leg raise test (passive and active). The measurement was performed before (pre-test) and after a training session (post-test). Spinal Mouse¿ was used to determine the angular values of the spinal curvatures and pelvic inclination. The specific tennis session lasted for two hours and had the following structure: 1) General warm up, with a total duration of 10 minutes. 2) Specific warm up, lasting for 10 minutes. 3) Specific technical training in which technical corrections to all technical skills were made (30 minutes). 4) Tactical training in controlled real game situations (30 minutes). 5) Real game situations: matches and modified competitions (40 minutes). CONCLUSION 1) In standing position, most of the players have normal angular values in the thoracic and lumbar curvatures. In relaxed sitting, almost half of the tennis players have normal values in the thoracic and lumbar curves, being more frequent values of mild thoracic kyphosis and moderate lumbar kyphosis. In the position of maximum trunk flexion, the players show a great mobility of the lumbar spine in the sagittal plane, showing a functional kyphosis in both thoracic and lumbar spinal curvatures, as in standing position most of the tennis players presented normal curves. 2) Standard tennis training generates slight changes in the sagittal plane of the spine and hamstring extensibility. Fatigue could be the cause of the decline in cases of normal values and increased hyperkyphotic positions in the thoracic spine and more cases of lumbar hypolordosis. These changes are not associated with significant changes in the pelvic tilt. The changes in the angular values after training in self-corrected posture show less postural control, which reduces the ability of the tennis player to modulate their sagittal spinal curvatures, probably due to muscle fatigue. Training does not seem to have a significant influence the seated positions. However, training causes a limitation of the pelvic bending movement associated with increased thoracic kyphosis. As for the effect of training on the extensibility of the hamstring muscles, a improvement of it occurs in all tests used for its assessment. 3) Two thirds of the players have normal values on the hamstring muscle extensibility. In assessing the hamstring extensibility with lineal test, an increase in cases of hamstring shortness is observed,which shows an alteration in lumbopelvic rhythm. For this reason, lineal tests are not suitable to assess hamstring extensibility in adolescent tennis players.