Confiabilidad entre instrumentos (T-Force y Myotest ) en la valoración de la fuerza. (Inter-machine Reliability (T-Force y Myotest ) in strength assessment).

The purpose of this study was to determine the inter-machine reliability of two devices routinely used to measure variables in sports performance: the linear position measuring device (LPM, isoinertial dynamometer T-Force) and the (AC) 3-D accelerometer (Myotest Sport, S4P model). 40 bench press exercises (25 kg) were analysed at concentric contraction phase and at maximum velocity, carried out by three different subjects (age: 26.74 ± 1.2 years, height: 175.74 ± 4.04 cm, weight: 78.7 ± 3.35 kg). Variables analysed comprised maximum velocity, maximum estimated force and estimated peak power. The data from both devices was collected simultaneously. Three simple lineal regression models were developed, supplied by the linear position measuring device (LPM) on the basis of the accelerometer’s (AC) data. The assumption of independence of errors was compared by means of the Durbin-Watson test. Partial autocorrelation coefficients were calculated for a p<.05 significance level. It has not been possible to confirm the presence of a general correlation between the measurements of both devices. The data was characterised by a generalised autocorrelation and it is recommended that strategies reflecting error control resulting from the data dependence factor be applied when measuring an athlete’s performance. An inter-machine correlation was only found in one of the non conclusive cases: (Peak Power) variable and subject 1, r(10) = .64, p = .024. No partial autocorrelation was found. The AC device obtained higher average and dispersion values than the LPM device. The results show the probability of an increase to the value of uncertainty of the AC device measurements in accordance with Metrology specified guidelines. Both devices should not be used interchangeably when assessing and monitoring training. Resumen El estudio pretende caracterizar la confiabilidad entre dos instrumentos, medidor de posicionamiento lineal (MPL, dinamómetro inercial T-Force) y el acelerómetro (AC) 3-D (Myotest Sport, modelo S4P), habituales en la medición de variables de rendimiento. Fueron analizados 40 ensayos en la realización del ejercicio press banca (25 kg) en fase concéntrica a la máxima velocidad por tres sujetos (26.74 ± 1.2 a os, 175.74 ± 4.04 cm, 78.7 ± 3.35 kg). Las variables analizadas fueron velocidad máxima, fuerza máxima estimada y pico de potencia estimado. Ambos aparatos obtuvieron los datos simultáneamente. Se desarrollaron tres modelos de regresión lineal simple proporcionados por el medidor de posicionamiento lineal (MPL) a partir de los datos del acelerómetro (AC).