Restricted access

Purchase article

USD  $24.95

Student 1 year subscription

USD  $107.00

1 year subscription

USD  $142.00

Student 2 year subscription

USD  $203.00

2 year subscription

USD  $265.00

Purpose: To assess the relationships between reactive strength measures and associated kinematic and kinetic performance variables achieved during drop jumps. A secondary aim was to highlight issues with the use of reactive strength measures as performance indicators. Methods: Twenty-eight national- and international-level sprinters, 14 men and 14 women, participated in this cross-sectional analysis. Athletes performed drop jumps from a 0.3-m box onto a force platform with dependent variables contact time (CT), landing time, push-off time, flight time, jump height (JH), reactive strength index (RSI, calculated as JH/CT), reactive strength ratio (RSR, calculated as flight time/CT), and vertical leg-spring stiffness recorded. Results: A Pearson correlation test found very high to near-perfect relationships between RSI and RSR (r = .91–.97), with mixed relationships between RSI, RSR, and the key performance variables (men: r = −.86 to −.71 between RSI/RSR and CT, r = .80–.92 between RSI/RSR and JH; women: r = −.85 to −.56 between RSR and CT, r = .71 between RSI and JH). Conclusions: The method of assessing reactive strength (RSI vs RSR) may be influenced by the performance strategies adopted, that is, whether athletes achieve their best reactive strength scores via low CTs, high JHs, or a combination. Coaches are advised to limit the variability in performance strategies by implementing upper and/or lower CT thresholds to accurately compare performances between individuals.

The authors are with Biomechanics Research Unit, Dept of Physical Education and Sport Sciences, University of Limerick, Limerick, Ireland.

Healy (robin.healy@ul.ie) is corresponding author.
  • 1.

    Nicol C, Avela J, Komi PV. The stretch-shortening cycle. Sports Med. 2006;36(11):977–999. PubMed ID: 17052133 doi:10.2165/00007256-200636110-00004

  • 2.

    Komi PV. Stretch-shortening cycle: a powerful model to study normal and fatigued muscle. J Biomech. 2000;33(10):1197–1206. PubMed ID: 10899328 doi:10.1016/S0021-9290(00)00064-6

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3.

    Enoka RM. Neuromechanics of Human Movement. Champaign, IL: Human Kinetics; 2015.

  • 4.

    Komi PV. Stretch-shortening cycle. In: Komi PV, ed. Strength and Power in Sport. Oxford, UK: Blackwell Science; 2003:184–202.

  • 5.

    Komi PV, Gollhofer A. Stretch reflexes can have an important role in force enhancement during SSC exercise. J Appl Biomech. 1997;13(4):451–460. doi:10.1123/jab.13.4.451

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6.

    Young W. Laboratory strength assessment of athletes. New Stud Athl. 1995;10:89–96.

  • 7.

    Newton RU, Dugan E. Application of strength diagnosis. Strength Cond J. 2002;24(5):50–59. doi:10.1519/00126548-200210000-00014

  • 8.

    Lockie RG, Jalilvand F, Callaghan SJ, Jeffriess MD, Murphy AJ. Interaction between leg muscle performance and sprint acceleration kinematics. J Hum Kinet. 2015;49(1):65–74.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9.

    Schmidtbleicher D. Training for power events. In: Komi PV, ed. Strength and Power in Sport. Boston, MA: Blackwell Scientific; 1992:169–179.

    • Search Google Scholar
    • Export Citation
  • 10.

    Bobbert MF, Huijing PA, van Ingen SG. Drop jumping. I. The influence of jumping technique on the biomechanics of jumping. Med Sci Sport Exer. 1987;19(4):332–338. PubMed ID: 3657481

    • Search Google Scholar
    • Export Citation
  • 11.

    Young WB, Pryor JF, Wilson GJ. Effect of instructions on characteristics of countermovement and drop jump performance. J Strength Cond Res. 1995;9(4):232–236.

    • Search Google Scholar
    • Export Citation
  • 12.

    Flanagan EP, Comyns TM. The use of contact time and the reactive strength index to optimize fast stretch-shortening cycle training. Strength Cond J. 2008;30(5):32–38 doi:10.1519/SSC.0b013e318187e25b

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13.

    Kipp K, Kiely MT, Giordanelli MD, Malloy PJ, Geiser CF. The reactive strength index reflects vertical stiffness during drop jumps. Int J Sports Physiol Perform. 2017;13(1):44–49. doi:10.1123/ijspp.2017-0021

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Markwick WJ, Bird SP, Tufano JJ, Seitz LB, Haff GG. The intraday reliability of the reactive strength index calculated from a drop jump in professional men’s basketball. Int J Sports Physiol Perform. 2015;10(4):482–488. PubMed ID: 25394213 doi:10.1123/ijspp.2014-0265

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15.

    Healy R, Kenny IC, Harrison AJ. Assessing reactive strength measures in jumping and hopping using the optojump (TM) system. J Hum Kinet. 2016;54(1):23–32. doi:10.1515/hukin-2016-0032

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Read MM, Cisar C. The influence of varied rest interval lengths on depth jump performance. J Strength Cond Res. 2001;15(3):279–283. PubMed ID: 11710651

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17.

    McNitt-Gray JL. Kinematics and impulse characteristics of drop landings from three heights. Int J Sport Biomech. 1991;7(2):201–224. doi:10.1123/ijsb.7.2.201

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Makaruk H, Czaplicki A, Sacewicz T, Sadowski J. The effects of single versus repeated plyometrics on landing biomechanics and jumping performance in men. Biol Sport. 2014;31(1):9–14. PubMed ID: 24917684 doi:10.5604/20831862.1083273

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19.

    McMahon TA, Cheng GC. The mechanics of running: how does stiffness couple with speed? J Biomech. 1990;23:65–78. PubMed ID: 2081746 doi:10.1016/0021-9290(90)90042-2

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20.

    Street G, McMillan S, Board W, Rasmussen M, Heneghan JM. Sources of error in determining countermovement jump height with the impulse method. J Appl Biomech. 2001;17(1):43–54. doi:10.1123/jab.17.1.43

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21.

    Farley CT, Glasheen J, McMahon TA. Running springs: speed and animal size. J Exp Biol. 1993;185(1):71–86. PubMed ID: 8294853

  • 22.

    Maloney SJ, Fletcher IM, Richards J. Reliability of unilateral vertical leg stiffness measures assessed during bilateral hopping. J Appl Biomech. 2015;31(5):285–291. PubMed ID: 25880542 doi:10.1123/jab.2014-0254

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23.

    Padua DA, Carcia CR, Arnold BL, Granata KP. Gender differences in leg stiffness and stiffness recruitment strategy during two-legged hopping. J Mot Behav. 2005;37(2):111–126. PubMed ID: 15730945 doi:10.3200/JMBR.37.2.111-126

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24.

    Hopkins W, Marshall S, Batterham A, Hanin J. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc. 2009;41(1):3–13. PubMed ID: 19092709 doi:10.1249/MSS.0b013e31818cb278

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25.

    Benjamini Y, Hochberg Y. Controlling the false discovery rate: a practical and powerful approach to multiple testing. J R Statist Soc Ser B (Methodological). 1995;57(1):289–300.

    • Search Google Scholar
    • Export Citation
  • 26.

    Arampatzis A, Schade F, Walsh M, Bruggemann GP. Influence of leg stiffness and its effect on myodynamic jumping performance. J Electromyogr Kinesiol. 2001;11(5):355–364. PubMed ID: 11595555 doi:10.1016/S1050-6411(01)00009-8

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 27.

    Arampatzis A, Bruggemann GP, Klapsing GM. Leg stiffness and mechanical energetic processes during jumping on a sprung surface. Med Sci Sports Exerc. 2001;33(6):923–931. PubMed ID: 11404657 doi:10.1097/00005768-200106000-00011

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 223 223 68
Full Text Views 18 18 2
PDF Downloads 14 14 1