Eccentric and Isometric Shoulder Rotation Strength and Range of Motion: Normative Values for Adolescent Competitive Tennis Players

Abstract

The aim of this cross-sectional study was to investigate isometric internal rotation (IR), external rotation (ER), abduction (ABD), and eccentric external rotation (eccER) shoulder strength and rotational range of motion (ROM) in adolescent male and female competitive tennis players. Additional aims of the study were to provide a tennis-specific normative database based on a large sample of players to deepen the knowledge regarding shoulder strength and ROM for adolescent competitive tennis players, and to discuss differences based on sex, age, and level of play. Shoulder strength and ROM was assessed in 301 adolescent competitive tennis players, 176 boys and 125 girls with a mean age of 14.6 and 14.4 years, respectively. Outcome variables of interest were isometric IR and ER strength, ABD strength, eccER shoulder strength, intermuscular strength ratios ER/IR and eccER/IR, IR ROM, ER ROM, and total range of motion (TROM). A General Linear Model two-way ANOVA was used to analyze differences in sex, age, and level of play. The findings of this study demonstrated age, side, and sex differences in the shoulder isometric strength, the eccER strength and ROM in adolescent competitive tennis players. Furthermore, when strength was expressed as ratios ER/IR and eccER/IR both sexes showed a lower ratio for eccER/IR in national players (0.95 ± 0.22 and 0.95 ± 0.23) compared to regional players (1.01 ± 0.32 and 1.07 ± 0.29) for male and female players, respectively. In conclusion, this paper presents a tennis-specific normative database for shoulder rotation strength and ROM in adolescent male and female competitive players. The key points in this evaluation are strength values normalized to body mass, intermuscular ratios, and TROM.

Shoulder range of motion in competitive tennis players: systematic review and meta-analysis

“…1 ). 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 16 , 17 , 18 , 19 , 21 , 22 , 25 , 27 , 28 , 29 , 30 , 33 , 34 , 35 , 36 Of the 25 studies, 5 only reported the ROM for the dominant shoulders, while 20 studies reported the ROM for both dominant and nondominant shoulders ( Table II ). Of the 25 studies, 12 measured the ROM with a goniometer, 10 with an inclinometer, 1 using photographs, 1 using a motion analysis system, and 1 using a dynamometer ( Table I ).…”

“…Furthermore, some studies reported that dominant shoulders have a greater prevalence of early signs of tendinosis and atrophy of the infraspinatus and supraspinatus tendons, ROM deficits, and increased strength. 6 , 13 , 16 , 38 However, it is believed that these are normal sport-adaptations instead of maladaptations. Studies should investigate the source of these adaptations, and whether they are due to soft-tissue or bony changes.…”

Posterior Shoulder Instability in Tennis Players: Aetiology, Classification, Assessment and Management

“…In such cases, it may be more appropriate to use normative dominant-arm TRROM values as a guide, which for adolescent tennis players has been shown to be 155.6 degrees in males and 160 degrees in females. 124…”

Is it time to de-normalize the normalization procedures based on ratio variables?

“…The rationale behind the use of ratio variables is to "normalize" for the denominator. Some examples are the scapulohumeral rhythm, 3 the between-limb normative ratio values 4 (i.e., limb strength asymmetry as a risk factor for sport injuries), the percent change of muscle thickness, 2 the percent change from baseline in clinical trials, the normalization procedures of electromyographic signals, or the Y-balance test (i.e., distance reached divided by lower limb length).…”