Normalization Considerations for Using the Unilateral Seated Shot Put Test in Rehabilitation

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To examine the effect of different normalization methods on unilateral seated shot put test results. BACKGROUND: The unilateral seated shot put test could assist clinical decision making in upper extremity rehabilitation, but test results must be normalized to compare across patients. The effect of normalization methods based on body size and upper-limb dominance is unknown. METHODS: One hundred twenty-five collegiate athletes (63 males) performed the unilateral seated shot put test with each upper extremity. Anthropometric measures (height, body mass, arm length) and distance thrown were recorded. Normalization based on body size included ratio scaling and allometric scaling. Ratio scaling was performed with the anthropometric measure having the highest correlation to distance thrown (distance/anthropometric measure). Allometric scaling was performed with body mass raised to the theoretical exponent 0.67 (distance/body mass(0.67)) and a derived exponent. Correlations of nonnormalized and normalized values with body mass were then determined. The limb symmetry index [(dominant-side distance/nondominantside distance) x 100] was used for normalization based on limb dominance. Sex differences were examined. RESULTS: Body mass was selected for ratio scaling, and 0.35 was the derived allometric-scaling exponent. Across sexes, only allometric scaling with the exponent 0.35 removed the correlation with body mass. The mean limb symmetry index exceeded 100% in males (108.7%) and females (104.4%), All normalized test results were higher in males. CONCLUSION: When using the unilateral seated shot put test in rehabilitation, allometric scaling with the exponent 0.35 is preferable, limb comparisons should account for 5% to 10% better performance on the dominant side, and performance benchmarks should be set within sex.