Table 1 Description of passive, active and reflexive parameters

Range of motion passive (degrees)

P_ROM

Slow passive movement through range of motion, maximum torque is 2 Nm. Range of motion equals the difference between minimal and maximal angle.

Stiffness in rest (Nm rad⁻¹)

P_k

Resistance to passive movement during a slow, position controlled, passive movement through range of motion. Average negative tangent of the hysteresis curve over 0.2 rad around P_RA.

Rest angle (degrees)

P_RA

Angle at which the resultant torque during a slow, position controlled, passive movement through range of motion is zero.

Active

Range of motion active (degrees)

A_ROM

Voluntary movement through range of motion, no resistance from haptic robot. Range of motion equals the difference between minimal and maximal angle.

Maximal voluntary contraction (Nm)

A_MVC

Maximal torque generated by participant. Fixed position at P_RA.

Control over joint torque (Nm)

A_CJT

Ability of participant to achieve steadily increasing target torque. Fixed position at P_RA.

Threshold angle (degrees)

R_ta

Angle at which the EMG exceeds 5 times the standard deviation of baseline during a fast, position controlled passive movement through total range of motion.

Reflex loop time (s)

R_lt

Time from perturbation onset to M₁-reflex onset. Participant is asked to deliver 10% of maximum EMG-activity during a position controlled movement over 0.14 rad at 3 rad/s.

Reflex contribution to joint resistance (Nms rad⁻¹)

R_kv

Participant is asked to resist fast multisine force pertur-bations. Velocity dependent reflex gain is computed using system identification methods.

Reflex modulation to environment (Nms rad⁻¹)

R_{m_env}

Participant is asked to resist fast multisine force pertur-bations in a damped environment. Velocity dependent reflex gain in a damped environment is computed.