| Purpose. The objectives of this study were to determine the validity and reliability of an accelerometer as a device for estimating force-time curve characteristics and examine the effect of reducing sampling frequency.;Methods. Sixty college aged men and women (age=23.63.1 y; height=180.16.3 cm; weight=85.015.2kg; body fat=14.26.5%) performed 10 restricted (no arm swing) zero-load countermovement vertical jumps each for a total of 600 jumps. Peak force, rate of force development, peak power output, peak velocity, flight time and peak vertical displacement were assessed with the use of a tri-axial accelerometer and compared to a force platform + linear position transducer system. The data from the accelerometer were then resampled to determine the optimum sampling frequency. Reliability was assessed by intraclass correlation (ICC) and coefficient of variance (CV). Validity was evaluated by a linear regression analyses to determine a calibration equation, the standard error of the estimate (SEE) and a validity correlation coefficient.;Results. The accelerometer was found to be reliable for peak force, peak power, peak velocity and peak displacement for each sampling frequency. In regards to validity, the accelerometer significantly overestimated peak force, peak rate of force development, peak power and displacement while it underestimated peak velocity.;Conclusions. The accelerometer was found to be a reliable device at frequencies as low as 50 Hz, with the best validity at 250 Hz; therefore, 250 Hz is an acceptable sampling frequency when testing with accelerometers. The accelerometer overestimates some variables, which may be due to including bodyweight in the calculations.;Key words. Performance Testing, Athlete Monitoring, Sport Science, Power, Countermovement Jump. |
