In recent years, the assessment of proprioceptive function has received increased attention in clinical and motor skill research. This is not surprising given the growing body of scientific evidence on the importance of proprioceptive information for controlling nearly all facets of human movement; from standing to performing highly skilled movement patterns in sports. In addition, the importance of proprioceptive information to promote motor learning and re-learning has been recognized. In

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... r article, Han et al. 1 reviewed several available methods for assessing proprioception, namely the threshold method for detection of passive motion, the method of joint position reproduction, and the authors' own method of active movement extent discrimination assessment (AMEDA). They advocated the AMEDA method as the method that is most versatile, simple to execute, and the one that provides ecological valid measures of joint proprioception. We would argue that before promoting or selecting a particular testing method for assessing proprioception, it is imperative to consider which of the proprioceptive senses, and which aspect of each sense, is to be evaluated. Unfortunately, there is no single, universally accepted method for testing all aspects of the various proprioceptive senses due to the complexity of the neurophysiological processes that encompass proprioception. 2 In our opinion, prior to selecting a proprioceptive testing method, the following questions need to be addressed: First, which proprioceptive sense shall be tested? It is well established that the various proprioceptive receptors give rise to several senses: the sense of limb and body position, the sense of limb and body motion, the sense of effort, the sense of force, and the sense of heaviness. 3 The most investigated senses in sport and clinical research are the senses of limb position and motion. 2 Second, which aspect of the sense under investigation shall be tested? The limits of a sensory system, like proprioception, are determined by the capabilities of its sensors and the underlying neurophysiological processes of integrating the responses from numerous receptors to achieve a stable percept. These limits are expressed by finding (a) the smallest stimulus intensity that can be detected, and (b) the smallest intensity to discriminate between two perceivable stimuli. 4 They are quantified by determining a detection threshold and a discrimination or just-noticeable-difference threshold. 4 After the relevant sense (e.g., motion or position sense) and the aspect (e.g., detection or discrimination) have been identified, a range of methods are available to the researcher. Yet, when presenting and reviewing the various testing methods, Han et al. 1 did not provide clear guidance which method is the most appropriate. Rather, in their review they contrast methods that are not directly comparable. The three methods that were presented (a) test different senses (i.e., joint motion vs. joint position sense), or (b) address different aspects of proprioception (i.e., detection of passive motion vs. discrimination of joint position). Thus, the reviewed methods (the threshold method for detection of passive motion, the method of joint position reproduction, and the method of active movement extent discrimination assessment) are not alternative methods. They speak to different senses and they test different aspects of the proprioceptive senses. Importantly, Han et al.