Maximal voluntary force and rate of force development in humans - importance of instruction

Abstract

The present investigation has been designed to confirm the effect of instruction (hard-and-fast instruction compared to fast instruction) upon maximal voluntary isometric force (MVF) and maximal rate of force development (MRFD) in muscle groups which differ with regards to muscle mass and usage. In addition, we took advantage of the force data collected during unilateral and bilateral leg extension, to compare the instruction effects on the indices of the bilateral deficits (BI, the differences between the data collected during bilateral extensions and the sum of the data collected during unilateral left and right extensions) with regard to MVF (BIMVF) and MRFD (BIMRFD). Force-time curves were recorded during maximal isometric contractions of the elbow flexors, the leg extensors of the take-off and lead legs and during bilateral leg extension in 26 healthy young male volunteers from the track-and-field national team of Tunisia. In the first protocol, the subjects were instructed to produce MFV as hard-and-fast as possible (instruction I). In the second protocol (instruction II) the subjects were instructed to provide MFRD, that is the most explosive force, by concentrating on the fastest contraction without concern for achieving maximal force. The present study confirmed the importance of an appropriate instruction for the measurement of MRDF The MRFD (F = 40.8, P < 0.001) were significantly higher when measured after instruction II compared to instruction I. The effect of the instruction upon MRFD were similar for muscle groups with different volumes, cortical representations and uses. The same results (F = 52.1; P < 0.001) were observed when MRFD was related to MVF [MRFD% = (MRFD/MVF) x 100]. On the other hand, MVF was similar following both instructions (ANOVA, F = 0.562; P = 0.454). Moreover, the results of the present study suggested that the effect of instruction was significantly larger for BIMRFD than for BIMVF.

Determinants of countermovement jump performance: a kinetic and kinematic analysis

“…Following dynamic stretching and submaximal warm up trials of incremental intensity, isometric unilateral knee extension torque was measured at five angles (15°, 30°, 45°, 60°, 75°; 0° indicated a fully extended leg) in a randomised order. Two trials were recorded at each angle, separated by 2 min rest: a 5 s maximal voluntary contraction; then a measure of rate of torque development, with the participant instructed to increase their knee extension torque as fast as possible (Sahaly, Vandewalle, Driss, & Monod, 2001). The participants rested for 3 min between each knee angle.…”

Determining the Optimal Whole-Body Vibration Dose–response Relationship for Muscle Performance

“…Several studies have looked at the effects of WBV on muscle performance. However, the results are not clear and are sometimes contradictory (9,(13)(14)(15)17,21,22,25,35,38,39 AU7 ). The variability in the protocols used by different authors may explain the inconsistency of the results presented in published studies (13).…”

“…Thus, research has focused on finding the optimal combination of these variables to reach maximal muscular response. For this purpose, frequency, amplitude, and duration were the main parameters analyzed (1,4,20,23,35,37).…”

“…With regard to the amplitude or peak-to-peak displacement, authors such as Cardinale and Bosco (12) [30][31][32][33][34][35] Hz, the best results in countermovement jump (CMJ) are obtained with amplitudes of 2-4 mm, whereas, with frequencies in the 40-to 50-Hz range, the greatest improvements are achieved with amplitudes of 4-6 mm.…”

Isometric Peak Force of Shoulder Rotators in Cricketers with and without History of Shoulder Pain

“…Following warm-up procedures, each subject was asked to force into external rotation as "hard and fast" as it produces optimal results for recording maximal force (Bemben et al, 1990;Sahaly et al, 2001;Haff et al, 2005).…”