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Table 2 Outcome measures and psychometric properties

From: Physical training in boys with Duchenne Muscular Dystrophy: the protocol of the No Use is Disuse study

Level Study outcome Measurement tool Psychometric properties Assessment
Body structures and functions Muscle endurance Six-Minute Bicycle Test* Feasible for ambulant and non-ambulant boys with DMD (pilot study, unpublished data) T0, T2, T5
  Joint mobility (PROM) Goniometry[55] (knee ext*, ankle dfl*, shoulder abd*▪, elbow ext*▪, wrist ext▪, wrist radial and ulnar dev▪) Standardized methods are feasible[56] and have good intra- and inter-rater reliability in DMD[57]
Passive wrist radial deviation is correlated with functional hand activities[58] and lower extremity contractures are related to onset of wheelchair reliance in DMD[4]
  Muscle strength Modified MRC[59] (hip ext*, knee ext* ankle dfl*, shoulder abd*▪, elbow ext*▪, wrist ext▪) Moderate to good intra-rater reliability[59] and acceptable inter-rater reliability in DMD after a training session[60]
Muscles with MRC grade 4 or 5 are difficult to measure with MMT, but muscles with MRC grade ≤3 are more difficult to measure with HHD[4]
  Muscle atrophy, intra-muscular fibrosis and fatty infiltration Quantitative skeletal muscle ultrasonography (muscle thickness and echo intensity) [61]: RF, TA, BB, FF*▪ Good inter-rater agreement in children[62]
High predictive values to discriminate between children with and without a NMD[63]
T2, T5, T6/T7*
  Bone density Dexascan (femur and lumbar spine)* Changes in bone mineral density can be detected with confidence in healthy boys ≥10 years after 6 months and in younger boys after 12 months[64], but a change in body shape may influence scan results[65] Conventional protocol for each boy
  Incidence of fractures Semi-structured interview*   All
Activities Functional abilities Motor Function Measure[37] (D1*, D2*, D3*▪) Excellent internal consistency for the global scale and the subscales in NMD[37]
Excellent to moderate intra- and inter-rater reliability in NMD[37]
Good face validity, convergent validity and discriminant validity in NMD[37]
Sufficiently sensitive to detect changes in the total score in DMD[66]
Total score predicts loss of ambulation in DMD[67]
  Upper limb function Action Research Arm Test[40, 41] ▪ Excellent intra-rater, inter-rater and test-retest reliability in stroke patients[40, 41]
Highly correlated with the Fugl-Meyer score47 and Functional Independence Measure48 in stroke patients
Suitable to detect changes over time in stroke patients[42]
  Functional abilities (grading) Vignos* and Brooke Scale*▪ [56] Good inter-rater and intra-rater reliability[57, 57] and correlated with timed tests[46, 68, 69] in DMD All
  Functional mobility Functional Mobility Scale[70] * A clinically feasible, valid and reliable tool in CP[70, 71] All
  Functional abilities (timed tests) Timed and graded functional tests (and total GSGC score) [72]: walk 10 meters, climb 3 stairs, rise from the floor and rise from a chair* Good to excellent intra- and inter-rater reliability in DMD[57, 73]
Sensitive to change in DMD: a small reduction in muscle force was accompanied by a large increase in time it takes to complete functional tests[74]
All (gait, stairs and chair only in the hospital)
  Finger dexterity Nine-hole Peg Test[75] *▪ Moderately high test-retest reliability, high inter-rater agreement and adequate concurrent validity in school-age children[76] All
  Hand function Jebsen-Taylor Hand Function Test[77] ▪ Good test-retest reliability in DMD[58]
Strongly correlated with muscle strength of the wrist extensors[58], radial deviation range of motion[58] and the Brooke scale[46] in DMD
T2, T4, T5
  Functional status PEDI[78, 79] (selfcare*▪ and mobility*) Good inter-rater and test-retest reliability[80], content validity[79] and discriminative validity[81] in children with various diagnosis
Feasible for evaluative purposes in CP[81, 82]
T0, T2, T4, T6/T7*
  Perceived manual abilities Abilhand[83] ▪ Abilhand-kids[84] * The Rasch-derived Abilhand is moderately related to grip and key pinch strength, has good test-retest reliability and may be sensitive to change in stroke patients[85]
The Abilhand-kids has good test-retest reliability and a higher independence in gross motor function is associated with a higher manual ability in CP[84]
T0, T2, T4, T6/T7*
  Quality of upper-limb motor function Melbourne Assessment of Unilateral Upper Limb Function[86] (item 1,2,3,10,11 and16) extended with an upper limb motion analysis (Vicon Motion Systems) with 8 cameras▪ The Melbourne Assessment has moderate to high intra- and inter-rater reliability[87] and excellent construct validity in CP[88]
A motion capture analysis system can measure task performance with an upper-limb orthosis[45], but soft tissue artefacts may negatively influence accuracy[49]
T2, T4
  Incidence and fear of falls Semi-structured interview*   All
Participation HRQoL KIDSCREEN-52[89](child- and parental questionnaire)*▪ Acceptable levels of reliability and validity in children and adolescents[90]
Children's most important in their lives generally map well to the items in KIDSCREEN[91]
T0, T2, T4, T6/T7*
Demographic variables Weight and height Body weight (kg)*▪, standing height* (cm) and arm-span*▪ (cm)   T0*, T2, T4, Y6/T7*
Co-factors Co-interventions Semi-structured interview*▪   All
  Physical activity Semi-structured interview (according to the PAQ-C[92] and the 60-min MVPA measure[93])*▪   All
  1. Symbols:* = study 1 'Dynamic leg and arm training', ▪ = study 2 'Functional training with arm support'
  2. Abbreviations: DMD: Duchenne Muscular Dystrophy; PROM: Passive Range of Motion; ext: extension; dfl: dorsal flexion; abd: abduction; dev: deviation; MRC: Medical Research Council Scale; RF: m. Rectus Femoris; TA: m. Tibialis Anterior; BB: m. Biceps Brachii; FF: forearm flexors; NMD: Neuromuscular Disease; GSGC: Gait, Stairs, Gowers, Chair; PEDI: Pediatric Evaluation of Disability Inventory; CP: cerebral palsy; HRQoL: Health-Related Quality of Life; PAQ-C Physical Activity Questionnaire for older children; MVPA: Moderate-to-Vigorous Physical Activity