Page 11 - Pol Grootswagers

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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