The concept of iso-inertial assessment: Reproducibility analysis and descriptive data

Abstract

The purpose of this study was to investigate the reproducibility of a new isoinertial dynamometer during bench press (BP) and squat (SQ) assessment and to provide descriptive data for recreational athletes. A position transducer and accelerometer were combined to assess velocity and power during free weight lifting exercises. Simulated movement with a pulley system revealed the excellent technological reproducibility of the dynamometer. Sixteen male subjects participated in the study in order to verify reproducibility in BP and SQ exercises. Iso-inertial tests consisted of lifting as fast as possible four different relative loads (35, 50, 70, 90% 1RM in BP and 45, 60, 75, 90% 1RM in SQ). The test was repeated one week later. Analysis of variance revealed no significant variation between sessions or trials. Reproducibility was better in velocity than in power, although it remained fairly good in both exercises (coefficients of variation [CV] never exceeding 10%), except on the time to peak power parameter. Descriptive data confirmed the classical force-velocity and force-power relationships for BP and SQ. In conclusion, this study demonstrated reliable measurements in BP and SQ iso-inertial exercises. Monitoring force-velocity and force-power relationships offers an original functional approach in strength training supervision.

The reliability of linear position transducer, force plate and combined measurement of explosive power-time variables during a loaded jump squat in elite athletes

“…These ICC values were similar to those previously reported in the literature for jumping movements (Alemany et al, 2005;Cormack et al, 2008;Hori et al, 2007;Jidovtseff and Croisier, 2006). The greater reliability associated with the force plate and combined methods has been previously attributed to the double differentiation required to calculate power from position data which may magnify noise present in the original position signal, increasing error of measurement (Cormie et al, 2007;Dugan et al, 2004).…”

“…Just as with force output, rate-dependent variables of power application may be of importance to human performance. Although there is a small body of research reporting reliability of rate of power development measures (Hori et al, 2009;Jidovtseff & Croisier, 2006), the absence of a comprehensive investigation into the reliability and validity of power-time measures has meant that their use in both clinical and research applications has been limited.…”

A comparison of the kinematics, kinetics and muscle activity between pneumatic and free weight resistance

“…Initiation of the eccentric phase was deWned as the Wrst instance of negative displacement, determined by searching the position array backwards from the point minimum displacement, which corresponded to the end of eccentric phase. The end of the concentric phase for the non ballistic conditions (FW and P) was deWned as the point of maximum displacement to maintain consistency with previous literature (Alamasbakk and HoV 1996;Asci and Acikada 2007;Cronin et al 2000Cronin et al , 2003Elliott et al 1989;JidovtseV et al 2006). For the ballistic analysis, the concentric phase was either terminated at the point at which the switch voltage rose above 1 V or maximum displacement, whichever occurred Wrst.…”

“…The end of the concentric phase was deWned as the point of peak displacement to maintain consistency with previous literature (Alamasbakk and HoV 1996;Asci and Acikada 2007;Cronin et al 2000Cronin et al , 2003Elliott et al 1989;JidovtseV et al 2006), but also to provide a comparison of the associated momentum between pneumatic and free weight resistance. As highlighted in Fig.…”

Movement Velocity as a Measure of Loading Intensity in Resistance Training

“…Velocity seems to be the steadiest parameter in isoinertial strength assessment [20] . Despite the fact that our subjects signifi cantly modifi ed their maximal strength levels as a result of 6-wk of training, the ICC obtained for MPV attained with each % 1RM, from 30 -95 % , when comparing test and retest were very high (0.81 -0.91; CV: 0.0 -3.6 % ), thus showing the high reliability of the velocity parameter and suggesting its use for strength assessment follow-up.…”