MOESM1 of Validity and reliability of simple measurement device to assess the velocity of the barbell during squats

Additional file 1:Figure S1. Start and end position of the ballistic squat exercise

Carpet skiing.

<p>Illustration of skiing on the indoor skiing carpet for trial condition 110A, wide turns. A) left turn, B) right turn. The rope was connecting an external weight with the athlete’s belt for keeping him centred on the carpet. The inertial sensors can be identified as the small white boxes and the reflective markers as the small grey dots. The carpet surface was designed such that ski gliding friction is minimized.</p

Dispersion of the calibration quaternions.

<p>Dispersion of the calibration quaternions.</p

Joint angle repeatability.

<p>Joint angle repeatability.</p

Sensor and marker placement.

<p>Sensor and marker placement from the back, front and side view. One additional inertial sensor was fixed to the athlete’s helmet (not shown).</p

3D knee angles with and without azimuth drift correction.

<p>Comparison of the 3D knee angles for the joint drift reduction without the proposed azimuth drift correction (light colours) and with the additional azimuth drift correction (dark colours).</p

Typical joint angles.

<p>Time normalized joint angles for the knee, hip and trunk of a typical athlete for 13 wide double turns (left and right turn) of trial 110B. The first 100% of the turn cycle is a left turn where the left leg is the inside leg. The second 100% of the turn cycle is a right turn where the left leg is the outside leg. Solid line is the average and dotted the standard deviation. Black is the reference system and blue the wearable system.</p

Overview of measurement protocol.

<p>Overview of measurement protocol.</p

Functional calibration movements.

<p>Functional calibration movements.</p

3D joint angles range of motion and errors.

<p>3D joint angles range of motion and errors.</p