Glenohumeral and scapulothoracic strength impairments exists in patients with subacromial impingement, but these are not reflected in the shoulder pain and disability index

Table 4 Final hierarchical regression analyses showing the additional variance in SPADI and SPADI-F score explained by each module included in the model

Modules of variables included in the model	SPADI		SPADI-F
Modules of variables included in the model	R²-adj	∆R²-adj^e	R²-adj.	∆R²-adj^e
Step 1: Covariates^a	23.6%	23.6%****	23.4%	23.4%****
Step 2: Pain module^b	55.2%	31.6%****	46.8%	23.4%****
Step 3: Impairment module^c	55.0%	−0.2%	47.2%	0.4%
Step 4: Kinesiophobia^d	55.5%	0.5%	47.1%	−0.1%

^* p < 0.05, ^** p < 0.01, ^*** p < 0.001, ^**** p < 0.0001
^aAge, Gender, Affected Side, Sick Leave, Medication Use
^bpAbd-ROM, pAbd-Strength, pER-Strength, Pain-last-week
^cAbd-ROM and ER-Strength. Abd-Strength was not included due to a risk of multicollinearity, as Abd-Strength and ER-Strength showed a correlation >0.7, when testing assumptions for the regression model
^dTampa scale of kinesiophobia (TSK-11)
^eAdditional variance explain by each step of the hierarchical regression model

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