In this article we present the definitions and the methods to calculate the leg parameters computed in Equi-Pro, which are available for each detected stride.
As described in the publication by Bosch et al. (2018), for a single limb, strides are delimited by the moment the hoof touches the ground; the stride duration is the time that passes between these events. A stride can be divided in a swing phase and a stance phase. The swing phase starts at the moment the hoof is lifted from the ground (the hoof-off moment) and ends when it touches the ground once more (the hoof-on moment). The stance phase is the period of time the hoof is on the ground.
The definition of a typical stride in terms of footfalls pattern for each gait is given at the following link: https://inertia-technology.com/techarticle/gaits-and-strides-in-equi-pro/. Please refer to this article for the suspension, diagonal advanced placement, and lateral advanced placement computations.
Stride-related parameters
The table below describes the stride-related parameters computed, as computed by the Equi-Pro application.
Table 1: Description of stride-related leg parameters per stride – temporal
CSV column name | Description | Additional info |
stride_dur | Stride duration in seconds. | |
stride_speed | Speed of the stride, in meters per second. | Available only if GNSS node. |
stride_length | Length of the stride, in meters. | Available only if GNSS node. |
duty_factor | Percentage of stance duration over stride duration, calculated as the average stance duration for all limbs, divided by the average stride duration. | From 0 to 100%, which is the percentage of stride duration during which the limb is in contact with the ground (stance phase). |
duty_factor_LR/RF/LH/RH | Percentage of stance duration over stride duration, for individual limbs. | See above. |
stance_dur_LF/RF/LH/RH | Stance phase duration for individual limbs, in seconds. | Calculated with the Limbs IMU, from detected hoof-on event to following hoof-off event. |
swing_dur_ LF/RF/LH/RH | Swing phase duration for individual limbs, in seconds. | Calculated with the Limbs IMU, from detected hoof-off event to following hoof-on event. |
swing_intensity_LF/RF/LH/RH | Sum of the absolute values of angular velocity in the sagittal plane divided by the duration of the swing phase, for individual limbs. | Calculated from the limbs gyroscope. |
suspension_L/R_sec | Left/Right suspension duration, in seconds. | Which limbs are used depends on the gait. |
suspension_L/R_perc | Left/Right Suspensions, expressed as a percentage of the stride duration. | Which limbs are used depends on the gait. |
suspension_sec | Suspension duration at canter, in seconds. | As there is only one suspension phase during canter, this variable does not have right/left distinction. |
suspension_perc | Suspension at canter, expressed as a percentage of the stride duration. | As there is only one suspension phase during canter, this variable does not have right/left distinction. |
DAP_L/R_sec | Diagonal Advanced Placement (DAP), in seconds; also called diagonal dissociation. | Calculated for walk, trot, canter, and tölt. |
DAP_L/R_perc | DAP, expressed as percentage of the stride | Calculated for walk, trot, canter, and tölt. |
LAP_L/R_sec | Lateral Advanced Placement (LAP), in seconds; also called lateral dissociation. | Calculated for walk, tölt and pace. |
LAP_L/R_perc | LAP, expressed as percentage of the stride. | Calculated for walk, tölt and pace. |
Angular-related leg parameters
As described by Bosch et al. (2018), the protraction is the forward extension of a limb, while the retraction of a limb is the backward extension. The protraction and retraction angles of the cannon bone are defined in Equi-Pro as the sagittal (forward/backward) swing angles of that bone during a stride relative to vertical.
The limb can also have a coronal angle during a stride; when the leg is tilted outwards it is called an abduction angle and when it is tilted inwards it is an adduction angle.
The protraction and retraction angles for the front limbs are illustrated in Figure 1 on the left side. The sagittal angles for the hind limbs are defined identically. On the right, Figure 1 also shows the coronal abduction/adduction angle for one hind limb.
In Equi-Pro, the protraction and retraction angles are determined at the respective hoof-on and hoof-off moments (displayed interactively in the Equi-Pro app) as well as the sagittal angle extrema (Protraction_Max and Retraction_Min, see Table 2). The abduction and adduction angles are determined as the coronal angle extrema only (Abduction_Max and Adduction_Min, see Table 2).
The sagittal Range Of Motion (ROM) is the full angular distance between retraction and protraction, as illustrated in Figure 2.

Figure 2 – Definition of the sagittal range of (angular) motion for the left front limb (ROM_Sagittal_LF).
The coronal Range Of Motion (ROM) is the full angular distance between abduction and adduction, as illustrated in Figure 3.

Figure 3 – Definition of the coronal range of (angular) motion for the left front limb (ROM_Coronal_LF).
The table below describes the angular-related leg parameters as computed by the Equi-Pro application.
Table 2: Description of angular-related leg parameters per stride – spatial
CSV column name | Description |
ROM_Sagittal_LF/RF/LH/RH | Angular range of motion (ROM) in the sagittal plane of each limb, in degrees. |
ROM_Coronal_LF/RF/LH/RH | Angular range of motion (ROM) in the coronal plane of each limb, in degrees. |
Protraction_Max_LF/RF/LH/RH | Maximum value in the sagittal plane, in degrees. |
Retraction_Min_LF/RF/LH/RH | Minimum value in the sagittal plane, in degrees. |
Abduction_Max_LF/RF/LH/RH | Maximum value in the coronal plane, in degrees. |
Adduction_Min_LF/RF/LH/RH | Minimum value in the coronal plane, in degrees. |