Between-system agreement of K-AI wearable tech (K-sport) and vector S7 global navigation satellite systems for measuring distance, velocity, and acceleration metrics

This study evaluated the agreement between K-AI Wearable Tech and the previously validated Vector S7 during an Australian football training session. Thirty sub-elite Australian football male players (21.6 ± 2.8 years) took part in the study. The K-AI Wearable Tech demonstrated mean absolute error (MAE) and root mean square error (RMSE) values of 74.1 m (1.00%) and 133.9 m (1.68%) for total distance, 52.6 m (6.46%) and 64.7 m (10.42%) for combined high-speed running-sprinting distance (&gt; 19 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ), 6.5 m (4.66%) and 9.8 m (6.51%) for sprinting distance (&gt; 25 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ). Acceleration and deceleration counts were 5.9 (13.92%) and 7.6 (17.04%), and 2.3 (10.07%) and 3.0 (13.66%), respectively. Peak and instantaneous velocity showed MAE and RMSE of 0.35 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> (1.20%) and 0.39 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> (1.35%), and 0.11 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> (2.26%) and 0.15 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> (3.03%), respectively. Mean biases (95% limits of agreement) were 64.2 m (−170.0 to 298.4) for total distance, 48.6 m (−36.6 to 133.8) for combined high-speed running-sprinting distance (&gt; 19 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ), and −4.0 m (−21.9 to 13.9) for sprinting distance (&gt; 25 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ). Acceleration and deceleration counts showed biases of −3.1 (−17.0 to 10.7) and 1.0 (−4.6 to 6.7), while peak and instantaneous velocity were 0.34 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> (−0.05 to 0.73) and 0.11 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="normal">km</mml:mi> <mml:mspace width="0.25em"/> </mml:mrow> <mml:mo>⋅</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math>