Reliability And Validity Of Three Wristbands In Running With Change Of Direction

Purpose: With the awakening of public fitness consciousness,more and more fitness people choose to use fitness wristbands to monitor their physical activities or exercise.The common indicators of fitness wristbands monitoring exercise intensity and quantity are heart rate and step index.Although they have acceptable reliability and validity in inline running,the reliability and validity of heart rate and step index of fitness wristbands in running with change of direction are not clear.The purpose of this re-search is to explore the reliability and validity of the heart rate(Mi Band and Fitbit)and the step index(Mi Band,Honor and Fitbit)of three brands of fitness wristbands at home and abroad in running with change of direction.Methods: Twenty-one male college students(23.76±1.84 yrs,176.43±5.58 cm,74.0±9.39kg)voluntarily took part in 8 tests of 10 m running with change of direction with duration of 5min(2 angles×4 speeds,90°and180°,4km/h,6km/h,8km/h,10 km,respectively abbreviated as 90-4,90-6,90-8,90-10,180-4,180-6,180-8,180-10).The speed of the running with change of direction was controlled by audio,and the subjects were required to reach specified redirection point when the audio was played.Six fitness wristbands(3 brands × 2 wristbands,Mi Band 4,Honor 4 and Fitbit Versa2)were worn at the same time during the test.The heart rate band and the motion camera were used to measure the heart rate and record during the whole test,and the video record was used to manually calculate the step count in the later period.The intra-group correlation coefficient(ICC)between the two wristbands of the same brand was calculated to test the reliability between devices.The data measured by the heart rate band and the manually calculated step count were respectively used as the "gold standard" of the heart rate and the step index,The intra-group correlation coefficient(ICC)and average absolute error ratio(MAPE)of the corresponding indexes of the fitness wristbands and the Gold Standard were calculated to test the validity of the heart rate and step index of the three brands of fitness wristbands.Results: In terms of reliability,the ICC of the heart rate index of the two Mi Band wristbands was 0.61-0.87(moderate to good)at 2 angles with change of direction and4 speeds,the ICC of the heart rate index of the two Fitbit wristbands was 0.62-0.74(moderate)at 90-4,90-6,180-10,and the ICC of the other conditions was less than0.60(low)or negative.Except for 90-4,90-8 and 180-10(0.76-0.79,good),the ICC of the step index of 2 Mi Band wristbands was more than 0.9(excellent)at 2 angles with change of direction and 4 speeds,and the ICC of the step index of 2 Honor wristbands was all more than 0.9(excellent)at 2 angles with change of direction and4 speeds.Except for 180-8(0.86,good),the ICC of the step index of 2 Fitbit wristbands was more than 0.9(excellent)at 2 angles with change of direction and 4speeds.In terms of validity,except for 10km/h,the ICC of heart rate index of Mi Band and heart rate band was all 0.67-0.85(moderate to good)at 2 angles with change of direction and 4 speeds,but only at 90-4,90-6,180-4,the MAPE of heart rate index of Mi Band and heart rate band was less than 10%.Except for 180-8(-0.34),the ICC of heart rate index of Fitbit wristband and heart rate band was all less than 0.60(low)at2 angles with change of direction and 4 speeds,but only at 90-8 and 180-6,the MAPE of heart rate index of Fitbit wristband and heart rate band was less than 10%.Except for 90-4 and 180-10(0.87 and 0.89,good),the ICC of the step count and manual count value of the Mi Band was all more than 0.9(excellent)at 2 angles and 4 speeds,and the MAPE of the step count and manual count value of the Mi Band was all less than 10%.The ICC of the step count and manual count value of Honor wristband was all more than 0.9(excellent)at 2 angles with change of direction and 4 speeds,and the MAPE of step count and manual count value of Honor wristband was all less than10%.Except for 90-4,90-10,180-10(negative)and 180-8(0.54,low),the ICC of the step count and manual count value of the Fitbit wristband was all more than 0.9(excellent)at 2 angles and 4 speeds,and the MAPE of the step count and manual count value of the Fitbit wristband was all less than or equal to 10%.Conclusions: The reliability and validity of fitness wristbands in measuring heart rate and step count in the running with change of direction were affected by the brand of the wristband,the angle with change of direction and the movement speed.In terms of heart rate index,the reliability of Mi Band was better than that of Fitbit,but the validity of both was not good as a whole.In terms of step index,the reliability and validity of Mi Band,Honor and Fitbit were all good,and Honor was better than Mi Band,Mi Band was better than Fitbit.Fitness people can choose different brands of fitness wristbands and different indicators of the same brand.