Table 7.

Summary of injury risk factors by quantity, quality, and level of evidence.

Studies	Level of Evidence	Level 1	Level 2			Level 3
	Risk Factor		RCT Study	Cohort Study	Cross-Sectional Study	Laboratory Study	Prospective Study	Studies
[22]	Scapulothoracic position				12 (26)			1
[22]	Muscle strength				12 (26)			1
[22]	Shoulder flexibility				12 (26)			2
[23]						8 (26)
[27]	Age-related shoulder/scapular adaptions				11 (26)			1
[32]	Racquet grip size					10 (26)		1
[24]	Racquet properties					5 (26)		1
[13]	Prolonged tennis						11 (26)	5
[29]	Effect of prolonged tennis to shoulder muscle fatigue					13 (26)
[20]	Effect of prolonged tennis to shoulder range of motion					10 (26)
[31]	Prolonged tennis may affect shoulder articular cartilage				12 (26)
[28]	Effect of prolonged tennis on glenohumeral rotation			14 (26)
[13]	Previous injury						11 (26)	2
[34]						13 (26)
[23]	Range of motion					8 (26)		1
[33]	Glenohumeral instability					12 (26)		1
[21]	Skills					13 (26)		2
[34]						13 (26)
[21]	Technique					13 (26)		2
[34]						13 (26)
[34]	Kinetic chain					13 (26)		1
[30]	Influence of fatigue on scapular kinematics		12 (26)					1
[35]	Scapulothoracic kinematics					13 (26)		1
[26]	Racquet polar moment of inertia					13 (26)		1
[36]	Shoulder rotational muscle imbalances				12 (26)			1
[37]	Correlation between scapular dyskinesia and Subacromial space				13 (26)			1
[25]	Racquet grip				12 (26)			1