Adaptive Alterations in Shoulder Range of Motion and Strength in Young Tennis Players.
BACKGROUND
Playing tennis requires unilateral and intensive movement of the upper limb, which may lead to functional adaptations of the shoulder and an increased injury risk. Identifying which athletes will be future elite tennis players starts at 5 to 6 years of age. Therefore, highly skilled players practice intensively in their childhood. However, whether these functional changes occur during the prepubertal years has not been established.


OBJECTIVE
To assess changes in glenohumeral-joint-rotation range of motion and strength of the shoulder-complex muscles in prepubertal elite tennis players.


METHODS
Cross-sectional study.


METHODS
Tennis training sports facilities.


METHODS
Sixty-seven male tennis players (age range = 7-13 years) selected by a regional tennis center of excellence were divided into 3 biological age groups relative to their predicted age at peak height velocity: greater than 4 (n = 26; age = 8.7 ± 0.7 years, height = 132.4 ± 12.9 cm, mass = 27.8 ± 3.8 kg), 3 to 4 (n = 21; age = 10.3 ± 0.6 years, height = 144.9 ± 5.7 cm, mass = 34.7 ± 4.0 kg), and 2 (n = 20; age = 12.8 ± 1.4 years, height = 158.5 ± 8.7 cm, mass = 43.0 ± 8.2 kg) years before their age at peak height velocity.


METHODS
We measured the internal- and external-rotation ranges of motion of the glenohumeral joint using a goniometer and calculated the total arc of motion. Maximal isometric strength of 8 shoulder muscles was measured using a handheld dynamometer. Strength values were normalized to body weight and used to calculate 4 agonist-to-antagonist strength ratios.


RESULTS
The total arc of motion of the glenohumeral joint decreased gradually with biological age (P ≤ .01) due to the decrease in internal-rotation range of motion (P < .001). Absolute strength increased gradually with biological age (P < .001), but the relative strengths and ratios remained similar.


CONCLUSIONS
Functional adaptations of the shoulder seen in adolescent and adult tennis players were observed in healthy prepubertal players. This knowledge could help clinicians and coaches more effectively monitor shoulder adaptations to tennis practice during the prepubertal years.
Université de Lyon, France.|Université Claude Bernard Lyon 1 Laboratoire Interuniversitaire de Biologie de la Motricité, Villeurbanne Cedex, France.|Laboratoire de Simulation et de Modélisation du Mouvement (S2M), Département de Kinésiologie, Université de Montréal, Laval, QC, Canada.
Benoit
B
Gillet
Université Claude Bernard Lyon 1 Laboratoire Interuniversitaire de Biologie de la Motricité, Villeurbanne Cedex, France.|Centre de Réadaptation Marie-Enfant-Centre Hospitalier d'Université Sainte Justine, Montréal, QC, Canada.
Mickaël
M
Begon
Aix-Marseille Université, Institut des Sciences du Mouvement Etienne-Jules Marey, Marseille, France.
Violaine
V
Sevrez
Université de Lyon, France.|IFSTTAR, Laboratoire de Biomécanique et Mécanique des Chocs, Bron, France.|Ligue du Lyonnais de Tennis, Bron, France.
Christian
C
Berger-Vachon
Université de Lyon, France.|Université Claude Bernard Lyon 1 Laboratoire Interuniversitaire de Biologie de la Motricité, Villeurbanne Cedex, France.
Isabelle
I
Rogowski
D000222:Adaptation, Physiological; D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D006801:Humans; D008297:Male; D009068:Movement; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D012785:Shoulder Joint / Q000502:physiology*; D013715:Tennis / Q000502:physiology*
children; glenohumeral joint; internal rotation; overhead throwing athletes; scapular muscles