Page 11 - Pol Grootswagers
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Introduction

            life were weaker, indicating that muscle strength is a stronger determinant of quality
            of life than muscle mass [15].

            The growing understanding of the more important role for muscle strength than for
            muscle mass in predicting functional decline and quality of life is reflected in the
            development of the sarcopenia guidelines. Where the initial definitions of sarcopenia
            were only based on muscle mass, the 2010 revised guidelines added muscle function
            to  the  definition  [16].  The  most  recent  guidelines  of  2019  have  even  put  muscle
            strength assessment in the first place of sarcopenia diagnosis [17]. Figure 1 shows
            the  consensus-based  algorithm  to  find  cases  for  sarcopenia  diagnosis,  with  the
            critical  position  of  muscle  strength  assessment  in  this  algorithm  highlighted  in
            yellow.  For  the  evaluation  of  muscle  strength  the  working  group  advises  the
            assessment of handgrip strength, by calibrated dynamometry under standardised
            conditions [18], or the chair rise test, a test in which participants have to stand up
            from a chair five times as quickly as possible, without using their arms [19].

            The working group acknowledge the limitation of handgrip strength measurements
            in those with hand disabilities caused by, for instance, arthritis or stroke. For these
            people,  they  advise  the  measurement  of  isometric  knee  extension  torque[17].
            Recently, further criticism was shown towards the use of handgrip measurements to
            assess muscle strength. Tieland et al. showed that handgrip strength failed to reflect
            considerable  increases  in  muscle  strength  [20].  Other  studies  have  shown  that,
            compared  to  handgrip  strength,  knee  extension  strength  is  a  better  predictor  of
            functional  performance  [21]  and  is  more  strongly  associated  with  health
            characteristics [22]. Isometric knee extension torque or force assessment might prove
            to be a more valid alternative, but more research on the validity of knee extension
            strength assessment methods that are suitable for clinical practice is still needed [23].





















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