The shoulder region has the highest incidence of acute injuries in the sport of surfing. Little is known about the strength profile at the shoulder in a surfing cohort. The primary aim of this study was to establish the reliability of a rotator cuff strength testing procedure for surfers with a secondary aim of providing a profile of internal and external rotation strength in a competitive surfing cohort. Shoulder internal rotation and external rotation isometric strength was measured using a hand-held dynamometer in 13 competitive surfers. Intra-class coefficient values ranged from 0.97 to 0.98 for intra-rater reliability and were lower for inter-rater reliability ranging from 0.80 to 0.91. Internal rotation strength was greater than external rotation strength bilaterally (dominant, p = 0.007, non-dominant, p < 0.001). No differences (p < 0.79) were found in internal rotation strength between the dominant and non-dominant arms. External rotation strength was weaker on the non-dominant arm compared with the dominant arm (p < 0.02). The non-dominant arm external rotation to internal rotation ratio (0.82 ± 0.15) was lower (p = 0.025) than the dominant arm (0.88 ± 0.14). The current procedure is reliable with the same clinician, and results indicate musculature asymmetry specific to the external rotators.

The shoulder region has the highest incidence of acute injuries in the sport of surfing. 10Little is known about the strength profile at the shoulder in a surfing cohort. The primary aim of 11 this study was to establish the reliability of a rotator cuff strength testing procedure for surfers with 12 a secondary aim of providing a profile of internal (IR) and external rotation (ER) strength in a 13 competitive surfing cohort. Shoulder IR and ER isometric strength was measured using a hand-held 14 dynamometer in 13 competitive surfers. Intra-class coefficient values ranged from 0.97 to 0.98 for 15 intra rater reliability and were lower for inter rater reliability ranging from 0.80 to 0.91. Normalised 16 force (N/Kg) for IR strength was significantly greater than ER strength bilaterally (dominant, p= 17 0.007, non-dominant, p<0.001). No significant differences (p< 0.79) were found in IR strength (N/Kg) 18 between the dominant and non-dominant arms. ER strength (N/Kg) was significantly weaker on 19 the non-dominant arm compared with the dominant arm (p<0.02). The non-dominant arm ER to IR 20 ratio (0.82 ± 0.15) was significantly (p=0.025) lower than the dominant (0.88 ± 0.14) The current 21 procedure is reliable with the same clinician, results indicate musculature asymmetry specific to the 22 external rotators. 23 24 25 26 42 the shoulder over opposing muscle groups. However, to the authors knowledge, there is no evidence 43 investigating strength profiles in a surfing cohort. 44While strength profiles have not been investigated in a surfing cohort, there is increasing 45 evidence to support the association between imbalance or weakness at the shoulder and injury risk 46 Preprints (www.preprints.org) | NOT PEER-REVIEWED | 93 their own results. A single examiner firstly conducted the entire test battery and was then followed 94 by the alternate examiner. A 5-minute rest period was employed during the transition from one 95 examiner to the next, as incorporated by Kelln, et al. [12]. The testing methodology including the 96 Preprints (www.preprints.org) | NOT PEER-REVIEWED |