Currently, the use of accelerometry to analyze training and competition is on the increase. Thus, accelerometers must be reliable when calculating different variables from raw data. The purpose of this investigation was to assess the reliability of triaxial accelerometers that contain inertial devices for measuring external loads in sports. Four and eight WIMU PRO™ inertial devices (RealTrack Systems, Almeria, Spain) were assessed in laboratory and specific sport conditions, respectively. The laboratory test was performed in static (with and without stress) and dynamic (10 and 30 Hz vibrations) conditions. In addition, two tests were performed during continuous and intermittent activity: (1) an incremental progressive running test on the treadmill and (2) 5 min of a Soccer-Specific Aerobic Field Test (SAFT90), where the devices were placed on ankle, knee, lower back and scapulae. Direct assessment of the accelerometers by calculating a vector magnitude, expressed as total acceleration (AcelT), was used for reliability using bias, ±95% limits of agreement and coefficient of variation. A t-test and Pearson’s r were performed for test–retest reliability. In the laboratory assessments, an excellent within- and between-device static (with and without stress) and dynamic reliability were found (coefficient of variation = 0.23%–0.78%). A very high reliability was also observed in the incremental treadmill test (coefficient of variation = 2.20%) and SAFT90 (coefficient of variation = 2.96%) with a nearly perfect correlation between devices (r = 0.99–1.00). Finally, in the between-sessions reliability analysis, excellent results (p = 0.46–0.98; t= 0.01–0.73) and a very strong correlation (r = 0.86–0.96) was found with p values greater than 0.05 indicating no differences between the tests. In conclusion, the accelerometers of the tested device have shown excellent results for within- and between-device reliability and in test–retest analysis. Thus, this device can calculate all variables that depend on accelerometry measurement such as PlayerLoad™ or impacts in different ranges, and in different anatomical locations.
HalsonSL.Monitoring training load to understand fatigue in athletes. Sports Med2014; 44: 139–147.
2.
BoydLJ. 2011A new way of using accelerometers in Australian rules football: assessing external loads. Doctoral dissertation, Victoria University, Melbourne, VIC, Australia.
3.
AkubatIBarrettSAbtG.Integrating the internal and external training loads in soccer. Int J Sports Physiol Perform2014; 9: 457–462.
4.
BradleyPSDi MascioMPeartDet al. High-intensity activity profiles of elite soccer players at different performance levels. J Strength Cond Res2010; 24: 2343–2351.
5.
BuchheitM.Monitoring training status with HR measures: do all roads lead to Rome?Front Physiol2014; 5: 73.
6.
BarrisSButtonC.A review of vision-based motion analysis in sport. Sports Med2008; 38: 1025–1043.
7.
AugheyRJ.Applications of GPS technologies to field sports. Int J Sports Physiol Perform2011; 6: 295–310.
8.
LeserRSchleindlhuberALyonsKet al. Accuracy of an UWB-based position tracking system used for time-motion analyses in game sports. Eur J Sport Sci2014; 14: 635–642.
9.
OgrisGLeserRHorsakBet al. Accuracy of the LPM tracking system considering dynamic position changes. J Sports Sci2012; 30: 1503–1511.
StevensTGAde RuiterCJvan NielCet al. Measuring acceleration and deceleration in soccer-specific movements using a local position measurement (LPM) system. Int J Sports Physiol Perform2014; 9: 446–456.
14.
CumminsCOrrRO’ConnorHet al. Global positioning systems (GPS) and microtechnology sensors in team sports: a systematic review. Sports Med2013; 43: 1025–1042.
15.
AkenheadRNassisGP.Training load and player monitoring in high-level football: current practice and perceptions. Int J Sports Physiol Perform2016; 11: 587–593.
16.
KrasnoffJBKohnMAChoyFKet al. Interunit and intraunit reliability of the RT3 triaxial accelerometer. J Phys Act Health2008; 5: 527–538.
17.
BoydLJBallKAugheyRJ.The reliability of MinimaxX accelerometers for measuring physical activity in Australian football. Int J Sports Physiol Perform2011; 6: 311–321.
18.
ChambersRGabbettTJColeMHet al. The use of wearable microsensors to quantify sport-specific movements. Sports Med2015; 45: 1065–1081.
19.
VanrenterghemJNedergaardNJRobinsonMAet al. Training load monitoring in team sports: a novel framework separating physiological and biomechanical load-adaptation pathways. Sports Med2017; 47: 2135–2142.
20.
BarrettSMidgleyALovellR.PlayerLoadTM: reliability, convergent validity, and influence of unit position during treadmill running. Int J Sports Physiol Perform2014; 9: 945–952.
21.
ClelandIKikhiaBNugentCet al. Optimal placement of accelerometers for the detection of everyday activities. Sensors2013; 13: 9183–9200.
22.
SchellingXTorresL.Accelerometer load profiles for basketball-specific drills in elite players. J Sports Sci Med2016; 15: 585–591.
23.
BoydLJBallKAugheyRJ.Quantifying external load in Australian football matches and training using accelerometers. Int J Sports Physiol Perform2013; 8: 44–51.
24.
NedergaardNJRobinsonMAEusterwiemannEet al. The relationship between whole-body external loading and body-worn accelerometry during team-sport movements. Int J Sports Physiol Perform2017; 12: 18–26.
25.
WhitesideDCantOConnollyMet al. Monitoring hitting load in tennis using inertial sensors and machine learning. Int J Sports Physiol Perform2017; 12: 1212–1217.
26.
BeanlandEMainLCAisbettBet al. Validation of GPS and accelerometer technology in swimming. J Sci Med Sport2014; 17: 234–238.
27.
SinclairJFau-GoodwinJRichardsJet al. The influence of minimalist and maximalist footwear on the kinetics and kinematics of running. Footwear Sci2016; 8: 33–39.
28.
JanssenISachlikidisA.Validity and reliability of intra-stroke kayak velocity and acceleration using a GPS-based accelerometer. Sports Biomech2010; 9: 47–56.
29.
MacdermidPWFinkPWMillerMCet al. The impact of uphill cycling and bicycle suspension on downhill performance during cross-country mountain biking. J Sports Sci2017; 35: 1355–1363.
30.
MacdermidPWFinkPWStannardSR.Transference of 3D accelerations during cross country mountain biking. J Biomech2014; 47: 1829–1837.
31.
KellySJMurphyAJWatsfordMLet al. Reliability and validity of sports accelerometers during static and dynamic testing. Int J Sports Physiol Perform2015; 10: 106–111.
32.
NicolellaDPTorres-RondaLSaylorKJet al. Validity and reliability of an accelerometer-based player tracking device. PLoS ONE2018; 13: e0191823.
33.
SimonsCBradshawEJ.Reliability of accelerometry to assess impact loads of jumping and landing tasks. Sports Biomech2016; 15: 1–10.
34.
BarreiraPRobinsonMADrustBet al. Mechanical Player Load™ using trunk-mounted accelerometry in football: is it a reliable, task- and player-specific observation?J Sports Sci2017; 35: 1674–1681.
35.
MuyorJMGranero-GilPPino-OrtegaJ.Reliability and validity of a new accelerometer (WIMU®) system for measuring velocity during resistance exercises. Proc Inst Mech Eng Part P J Sports Eng Technol2017; 232: 218–224.
36.
Bastida CastilloAGómez CarmonaCDDe la Cruz SánchezEet al. Accuracy, intra- and inter-unit reliability, and comparison between GPS and UWB-based position-tracking systems used for time–motion analyses in soccer. Eur J Sport Sci2018; 18: 450–457.
37.
Muñoz-LópezAGranero-GilPPino-OrtegaJet al. The validity and reliability of a 5-Hz GPS device for quantifying athletes’ sprints and movement demands specific to team sports. J Hum Sport Exerc2017; 12: 156–166.
38.
Molina-CarmonaIGomez-CarmonaCDBastida CastilloAet al. Validez del dispositivo inercial WIMU PRO™ para el registro de la frecuencia cardíaca en un test de campo. Sport TK Rev Euroam Cienc Deporte2018; 7: 81–86.
39.
MuyorJ.Validity and reliability of a new device (WIMU®) for measuring hamstring muscle extensibility. Int J Sports Med2017; 38: 691–695.
40.
Pino-OrtegaJHernández-BelmonteABastida-CastilloAet al. Evaluación de la velocidad angular en el test de elevación activa de la pierna recta: validez y fiabilidad de un dispositivo inercial (WIMU PRO). E-Balonmano Com Rev Cienc Deporte2018; 14: 79–88.
41.
Pino-OrtegaJGarcía-RubioJIbáñezSJ.Validity and reliability of the WIMU inertial device for the assessment of the vertical jump. PeerJ2018; 6: e4709.
42.
BoeremaSvan VelsenLSchaakeLet al. Optimal sensor placement for measuring physical activity with a 3D accelerometer. Sensors2014; 14: 3188–3206.
43.
ÖzdemirA.An analysis on sensor locations of the human body for wearable fall detection devices: principles and practice. Sensors2016; 16: 1161.
44.
ThompsonCJLuckLMKeshwaniJet al. Location on the body of a wearable accelerometer affects accuracy of data for identifying equine gaits. J Equine Vet Sci2018; 63: 1–7.
45.
WaldronMTwistCHightonJet al. Movement and physiological match demands of elite rugby league using portable global positioning systems. J Sports Sci2011; 29: 1223–1230.
46.
KunzeKBahleGLukowiczPet al. Can magnetic field sensors replace gyroscopes in wearable sensing applications? In: Proceedings of the international symposium on wearable computers (ISWC), Seoul, South Korea, 10–13 October 2010, pp. 1–4. New York: IEEE.
47.
O’DonovanKJKamnikRO’KeeffeDTet al. An inertial and magnetic sensor based technique for joint angle measurement. J Biomech2007; 40: 2604–2611.
48.
Van HeesVTSlootmakerSMDe GrootGet al. Reproducibility of a triaxial seismic accelerometer (DynaPort). Med Sci Sports Exerc2009; 41: 810–817.
49.
SmallKMcNaughtonLGreigMet al. The effects of multidirectional soccer-specific fatigue on markers of hamstring injury risk. J Sci Med Sport2010; 13: 120–125.
50.
FieldA.Discovering statistics using IBM SPSS statistics. 4th ed.London: SAGE, 2013.
51.
BlandJMAltmanDG.Measuring agreement in method comparison studies. Stat Methods Med Res1999; 8: 135–160.
52.
HopkinsWGMarshallSWBatterhamAMet al. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc2009; 41: 3–13.
53.
EdwardsSWhiteSHumphreysSet al. Caution using data from triaxial accelerometers housed in player tracking units during running. J Sports Sci; 37(7): 810–818.
54.
NicholsJFMorganCGSarkinJAet al. Validity, reliability, and calibration of the Tritrac accelerometer as a measure of physical activity. Med Sci Sports Exerc1999; 31: 908–912.
