Both tennis players and other athletes have some imbalance in how strongly each shoulder blade muscle works, but tennis players are more balanced when their arms are raised high, and more unbalanced when their arms are at a lower angle—like during a tennis stroke.
Scientific Claim
Muscle symmetry during bilateral scapular retraction is generally below the normal threshold (90%) in both tennis players and non-tennis athletes, but tennis players show slightly higher symmetry at 90° and greater asymmetry at 45°, indicating angle-specific neuromuscular adaptations related to sport-specific movement patterns.
Original Statement
“Muscle symmetry was slightly higher in tennis players at 90°, but asymmetry increased at 45°, suggesting angle-specific adaptations. Both groups demonstrated symmetry indices that were below the normal threshold of 90%, with some values in the borderline or asymmetrical ranges (e.g., 75–82%).”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The claim uses 'show' and 'suggesting' to reflect observed trends without implying causation. The study design supports descriptive and correlational claims about symmetry patterns across angles.
Evidence from Studies
Supporting (1)
Tennis players’ shoulders work differently depending on how high their arms are raised—more balanced at 90° but less balanced at 45°—because their sport trains one side more, changing how their muscles respond.