Scapulohumeral kinematic assessment of the forward kayak stroke in experienced whitewater kayakers

By understanding the normal humeral and scapular kinematics during the kayak stroke, inferences about the relationship of kayaking technique and shoulder injury may be established. The purpose of this study was to describe scapular and humeral kinematics and to compare dominant versus non-dominant symmetry in healthy whitewater kayakers performing the forward stroke. Twenty-five competent whitewater kayakers (mean age: 34.1 ± 9.4 years, mean height: 1.768 ± 0.093 m, mean mass: 78.2 ± 13.0 kg) underwent humeral and scapular kinematic assessment, using an electromagnetic tracking device, while kayaking on a kayak ergometer. Paired t-tests were used to determine symmetry. Scapular and humeral kinematic means and standard deviations at six time points during the kayak stroke were described. Scapular and humeral kinematics were shown to be similar upon bilateral comparison. The greatest potential for injury during the forward stroke may be at thrust paddle shaft vertical when the humerus is maximally elevated in internal rotation and adduction as subacromial structures may be mechanically impinged. The relationship between scapulohumeral kinematics related to injury at other time points are also described.     

The Effects of Alternative Flowcharting Techniques on Performance on Procedural Tasks

Many individuals tend to have difficulty completing complex procedural tasks that require branching. Neither prose–based nor list–based instructions have been efficient in alleviating this difficulty. Traditional flowcharts have proven more effective in helping individuals to complete complex procedural tasks, but only after several practice sessions. However, it is possible that the use of map–like symbols may eliminate the need for repeated flowchart practice. Therefore, the purpose of this study was to investigate the effects of flowcharts utilizing map–like symbols on performer efficiency in completing a complex procedural task. The results of this study indicated no significant difference between the use of map–like symbols and traditional flowcharts in helping performers to complete complex procedural tasks. However, both graphic presentation formats were found to be significantly more efficient than a list–based presentation of information. It was expected than an intuitive map–like presentation would be more efficient than a list–based format. However, the efficiency of the flowchart presentation under unpracticed conditions was unexpected, based on prior research.