Explosive Strength of the Knee Extensors: The Influence of Criterion Trial Detection Methodology on Measurement Reproducibility

Restricted access


The present study was conducted to assess test-retest reproducibility of explosive strength measurements during single-joint isometric knee extension using the IsoMed 2000 dynamometer. Thirty-one physically active male subjects (mean age: 23.7 years) were measured on two occasions separated by 48–72 h. The intraclass correlation coefficient (ICC 2,1) and the coefficient of variation (CV) were calculated for (i) maximum torque (MVC), (ii) the peak rate of torque development (RTDpeak) as well as for (iii) the average rate of torque development (RTD) and the impulse taken at several predefined time intervals (0–30 to 0–300 ms); thereby explosive strength variables were derived in two conceptually different versions: on the one hand from the MVC-trial (version I), on the other hand from the trial showing the RTDpeak (version II). High ICC-values (0.80–0.99) and acceptable CV-values (1.9–8.7%) could be found for MVC as well as for the RTD and the impulse taken at time intervals of ≥100 ms, regardless of whether version I or II was used. In contrast, measurements of the RTDpeak as well as the RTD and the impulse taken during the very early contraction phase (i.e. RTD/impulse0–30ms and RTD/impulse0–50ms) showed clearly weaker reproducibility results (ICC: 0.53–0.84; CV: 7.3–16.4%) and gave rise to considerable doubts as to clinical usefulness, especially when derived using version I. However, if there is a need to measure explosive strength for earlier time intervals in practice, it is, in view of stronger reproducibility results, recommended to concentrate on measures derived from version II, which is based on the RTDpeak-trial.

Aagaard P, Simonsen EB, Andersen JL, Magnusson P, Dyhre-Poulsen P. Increased rate of force development and neural drive of human skeletal muscle following resistance training. J Appl Physiol (1985), 2002; 93(4): 1318-1326

Andersen LL, Aagaard P. Influence of maximal muscle strength and intrinsic muscle contractile properties on contractile rate of force development. Eur J Appl Physiol, 2006; 96(1): 46-52

Andersen LL, Andersen JL, Zebis MK, Aagaard P. Early and late rate of force development: differential adaptive responses to resistance training? Scand J Med Sci Sports, 2010; 20(1): 162-169

Atkinson G, Nevill AM. Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. Sports Med, 1998; 26(4): 217-238

Bassey EJ, Fiatarone MA, O’Neill EF, Kelly M, Evans WJ, Lipsitz LA. Leg extensor power and functional performance in very old men and women. Clin Sci (Lond), 1992; 82(3): 321-327

Baumgartner TA. Norm-referenced measurement: reliability. IL: Human Kinetics, 45-72; 1989

Blazevich AJ, Horne S, Cannavan D, Coleman DR, Aagaard P. Effect of contraction mode of slow-speed resistance training on the maximum rate of force development in the human quadriceps. Muscle Nerve, 2008; 38(3): 1133-1146

Buckthorpe MW, Hannah R, Pain TG, Folland JP. Reliability of neuromuscular measurements during explosive isometric contractions, with special reference to electromyography normalization techniques. Muscle Nerve, 2012; 46(4): 566-576

de Ruiter CJ, Kooistra RD, Paalman MI, de Haan A. Initial phase of maximal voluntary and electrically stimulated knee extension torque development at different knee angles. J Appl Physiol (1985), 2004; 97(5): 1693-1701

Dirnberger J, Huber C, Hoop D, Kösters A, Müller E. Reproducibility of concentric and eccentric isokinetic multi-joint leg extension measurements using the IsoMed 2000-system. Isokinet Exerc Sci, 2013; 21(3): 195-202

Dvir Z. Isokinetics: muscle testing, interpretation, and clinical applications. Edinburgh; New York: Churchill Livingstone; 2004

Fleming BE, Wilson DR, Pendergast DR. A portable, easily performed muscle power test and its association with falls by elderly persons. Arch Phys Med Rehabil, 1991; 72(11): 886-889

Gruber M, Gruber SB, Taube W, Schubert M, Beck SC, Gollhofer A. Differential effects of ballistic versus sensorimotor training on rate of force development and neural activation in humans. J Strength Cond Res, 2007; 21(1): 274-282

Hannah R, Minshull C, Buckthorpe MW, Folland JP. Explosive neuromuscular performance of males versus females. Exp Physiol, 2012; 97(5): 618-629

Jordan MJ, Aagaard P, Herzog W. Rapid hamstrings/quadriceps strength in ACL-reconstructed elite alpine ski racers. Med Sci Sports Exerc, 2015; 47(1): 109-119

Kuitunen S, Komi PV, Kyrolainen H. Knee and ankle joint stiffness in sprint running. Med Sci Sports Exerc, 2002; 34(1): 166-173

Looney MA. When the intraclass correlation coefficient in misleading. Meas Phys Educ Exerc Sci, 2000; 4(2): 73-78

Luhtanen P, Komi PV. Mechanical power and segmental contribution to force impulses in long jump takeoff. Eur J Appl Physiol Occup Physiol, 1979; 41(4): 267-274

Prieske O, Wick D, Granacher U. Intrasession and intersession reliability in maximal and explosive isometric torque production of the elbow flexors. J Strength Cond Res, 2014; 28(6): 1771-1777

Shrout PE, Fleiss JL. Intraclass correlations: uses in assessing rater reliability. Psychol Bull, 1979; 86(2): 420-428

Sukop J, Nelson RC. Effects of isometrical training on the force-time characteristics of muscle contractions. IL: Human Kinetics; 1974

Thorstensson A, Karlsson J, Viitasalo JH, Luhtanen P, Komi PV. Effect of strength training on EMG of human skeletal muscle. Acta Physiol Scand, 1976; 98(2): 232-236

Tillin NA, Jimenez-Reyes P, Pain MT, Folland JP. Neuromuscular performance of explosive power athletes versus untrained individuals. Med Sci Sports Exerc, 2010; 42(4): 781-790

Vincent WJ, Weir JP. Statistics in kinesiology. Champaign, IL: Human Kinetics; 2012

Weir JP. Quantifying test-retest reliability using the intraclass correlation coefficient and the SEM. J Strength Cond Res, 2005; 19(1): 231-240

Weyand PG, Sternlight DB, Bellizzi MJ, Wright S. Faster top running speeds are achieved with greater ground forces not more rapid leg movements. J Appl Physiol (1985), 2000; 89(5): 1991-1999

Zatsiorsky VM. Science and practice of strength training. Champaign, IL: Human Kinetics; 1995

Journal of Human Kinetics

The Journal of Academy of Physical Education in Katowice

Journal Information

IMPACT FACTOR 2017: 1.174
5-year IMPACT FACTOR: 1.634

CiteScore 2017: 1.31

SCImago Journal Rank (SJR) 2017: 0.516
Source Normalized Impact per Paper (SNIP) 2017: 0.906


  • View in gallery

    Testing position on the IsoMed 2000 dynamometer

  • View in gallery

    An example of a torque-time curve recorded during a trial of maximal isometric knee extension. Time 0 corresponds to the onset of the torque curve, which was determined when the torque exceeded a value of 7.5 Nm. MVC was defined as the highest torque value. RTDpeak was defined as the peak slope of the torque-curve. Average RTD and contractile impulse (here shown for 0–200 ms) were determined from the slope and the area under the torque-time curve at time intervals of 30, 50, 100, 200 and 300 ms, respectively, from the onset of contraction.


All Time Past Year Past 30 Days
Abstract Views 252 252 54
Full Text Views 46 41 0
PDF Downloads 13 12 0