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Table 3 The muscle strength, disease activity and damage scores, and twitch interpolation results of patients with myositis

From: Voluntary activation failure is detectable in some myositis patients with persisting quadriceps femoris weakness: an observational study

QF (MVC) Strength category Patient number QF mass-normalised force F/LBM (N/kg) Activity status Damage score (0–3) Twitch status (-/+)
"Not weak" 1 8.83 Inactive 0 -
  2 7.17 Active - 1 -
  4 5.64 Active - 1 -
  5 5.63 Inactive 1 -
  6 5.40 Inactive 1 -
  3 6.40 Inactive 2 +
"Weak" 7 4.14 Active - 1 -
  8 3.97 Active - 1 -
  9 3.69 Active 1 -
  11 2.82 Active 1 -
  12 2.28 Inactive 3 -
  14 2.10 Active 1 -
  *17 1.30 Active 3 -
  *19 0.99 Inactive 3 -
  10 3.32 Active 1 +
  13 2.11 Active - 2 +
  15 1.84 Active - 3 +
  16 1.76 Active - 1 +
  18 1.00 Active + 2 +
  20 0.80 Inactive 3 +
  1. Twenty patients with myositis listed according to their mass-normalised strength and twitch interpolation results, and stratified as "not weak" and "weak" according to their F/LBM results (see text). In general terms, as QF strength decreased, the incidence of positive twitches increased. Cases 17 and 19 had had muscle biopsies within the previous 6 months, and the results showed end-stage disease with severe muscle atrophy and fibrosis. F/LBM, force per units of lean body mass; MVC, maximum voluntary contraction; QF, quadriceps femoris.
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