Table 2 Main characteristics of selected studies analyzing validity of the myotonometry in the lower limbs.

Fröhlich-Zwahlen et al.⁴²

N = 40

20 chronic stroke patients

Mean age = 52, SD = 11

9 women

Mean time post stroke (y) = 1.9, SD = 0.7

20 healthy controls

Mean age = 53, SD = 10

9 women

MyotonPRO:

Muscle tone, stiffness, and elasticity at rest

MB:

Vastus lateralis

Rectus femoris

TA

Biceps femoris

GM Medialis

1. US: Muscle and subcutaneous tissue thickness

2. Dynamometer:

Isometric strength (MVC) of the knee extensor and flexor, plantar flexor and dorsiflexor muscles

Relaxed supine and prone position (MyotonPRO and US), standard seated position (dynamometer) 1 h session

1. MyotonPRO: 10 single trials at rest in each muscle. Impulse force 0.4 N of 15 ms duration. 1 s interval between trials

2. US: 2 longitudinal or transverse pictures with a short break

3. Dynamometer: 3 trials of 5 s duration. 30 s interval between trials

Low to fair correlations between muscle strength or muscle thickness and muscle tone, stiffness and elasticity

Group effect for stiffness of the medialis GM

Rydahl & Brouwer⁴⁵

N = 47

23 chronic stroke patients

Mean age = 67.5, SD = 10.9

9 women

Mean time post stroke (y) = 4.6, SD = 3.3

24 healthy controls

Mean age = 71.2, SD = 9

11 women

Myotonometer:

Muscle compliance at rest and during 10% MVC

MB: GM

1. MAS test of the plantar flexor muscles: Muscle tone

2. Torque motor and electric stimulator: Stiffness of ankle muscles (total, passive, intrinsic and reflex stiffness)

Seated with lower limbs hanging (MAS test), semi-reclined position with test leg in a support frame, 90° between trunk and hip, and 45° knee flexion (torque motor and myotonometer) 1 h session

1. MAS test

2. Torque motor: 1 kHz per channel over 1050-ms, with 500-ms pre- and post perturbation. 5 trials for condition: rest, voluntary 10% of MVC, and involuntary 10% of MVC (electric stimulation of the posterior tibial nerve in the popliteal fossa for less than 5 s, with 1-ms square-wave pulses at 30 Hz. Perturbation of 5° at 100°/s in all conditions

3. Myotonometer: 3 trials at rest, and 3 trials during 10% of MVC. Force intervals of 2.5 N over a range from 2.5 to 20 N

Differences in compliance between rest and 10% MVC were negatively correlated with higher MAS scores and total ankle stiffness. Low to fair association observed

No main group effect for muscle compliance at rest or during 10% VC

Differences between stroke patients and controls in muscle compliance for the AUC, and the percentage difference between rest and contracted conditions