European Journal of Applied Physiology

, Volume 96, Issue 3, pp 305–314 | Cite as

Effects of isometric squat training on the tendon stiffness and jump performance

  • Keitaro Kubo
  • Hideaki Yata
  • Hiroaki Kanehisa
  • Tetsuo Fukunaga
Original Article


The present study aimed to investigate the effect of isometric squat training on human tendon stiffness and jump performances. Eight subjects completed 12 weeks (4 days/week) of isometric squat training, which consisted of bilateral leg extension at 70% of maximum voluntary contraction (MVC) for 15 s per set (10 sets/day). Before and after training, the elongations of the tendon–aponeurosis complex in the vastus lateralis muscle and patella tendon were directly measured using ultrasonography while the subjects performed ramp isometric knee extension up to MVC. The relationship between the estimated muscle force and tendon elongation was fitted to a linear regression, the slope of which was defined as stiffness. In addition, performances in two kinds of maximal vertical jumps, i.e. squatting (SJ) and counter-movement jumps (CMJ), were measured. The training significantly increased the volume (P<0.01) and MVC torque (P<0.01) of the quadriceps femoris muscle. The stiffness of the tendon–aponeurosis complex increased significantly from 51±22 (mean ± SD) to 59±24 N/mm (P=0.04), although that of the patella tendon did not change (P=0.48). The SJ height increased significantly after training (P=0.03), although the CMJ height did not (P=0.45). In addition, the relative difference in jump height between SJ and CMJ decreased significantly after training (P=0.02). These results suggest that isometric squat training changes the stiffness of human tendon–aponeurosis complex in knee extensors to act negatively on the effects of pre-stretch during stretch-shortening cycle exercises.


Resistance training Elongation Ultrasonography Vastus lateralis muscle 


  1. Akima H, Kubo K, Kanehisa H, Suzuki Y, Gunji A, Fukunaga T (2000) Leg-press resistance training during 20 days of 6 head-down-tilt bed rest prevents muscle deconditioning. Eur J Appl Physiol 82:30–38PubMedCrossRefGoogle Scholar
  2. Anderson FC, Pandy MG (1993) Storage and utilization of elastic strain energy during jumping. J Biomech 26:1413–1427PubMedCrossRefGoogle Scholar
  3. Ball JR, Rich GQ, Wallis EL (1964) Effects of isometric training on vertical jumping. Res Quart 35:231–235Google Scholar
  4. Berger RA (1963) Effects of dynamic and static training on vertical jumping ability. Res Quart 34:419–424Google Scholar
  5. Bobbert MF, Gerritsen KGM, Litjens MCA, Van-Soest AJ (1996) Why is countermovement jump height greater than squat jump height? Med Sci Sports Exerc 28:1402–1412PubMedGoogle Scholar
  6. Bojsen-Moller J, Magnusson SP, Raundahl LR, Kjaer M, Aagaard P (2005) Muscle performance during maximal isometric and dynamic contractions is influenced by the stiffness of the tendinous structures. J Appl Physiol 99:986–994PubMedCrossRefGoogle Scholar
  7. Cavagna GA, Citterio G, Jacini P (1981) Effects of speed and extent of stretching on the elastic properties of active frog muscle. J Exp Biol 91:131–143Google Scholar
  8. Cavagna GA, Dusman B, Margaria R (1968) Positive work done by a previously stretched muscle. J Appl Physiol 24:21–23PubMedGoogle Scholar
  9. Duchateau J, Hainaut K (1984) Isometric or dynamic training: differential effect on dynamic properties of human muscle. J Appl Physiol 56:296–301PubMedGoogle Scholar
  10. Goubel F (1987) Muscle mechanics fundamental concepts in stretch-shortening cycle. Med Sport Sci 26:24–35Google Scholar
  11. Hakkinen K, Alen M, Komi PV (1985) Changes in isometric force- and relaxation-time, electromyographic and muscle fibre characteristics of human skeletal muscle during strength training and detraining. Acta Physiol Scand 125:573–585PubMedGoogle Scholar
  12. Hansen P, Aagaard P, Kjaer M, Larsson B, Magnusson SP (2003) Effect of habitual running on human achilles tendon load-deformation properties and cross-sectional area. J Appl Physiol 95:2375–2380PubMedGoogle Scholar
  13. Isear JA, Erickson JC, Worrell TW (1997) EMG analysis of lower extremity muscle recruitment patterns during an unloaded squat. Med Sci Sports Exer 29:532–539Google Scholar
  14. Ito M, Kawakami Y, Ichinose Y, Fukashiro S, Fukunaga T (1998) Nonisometric behavior of fascicles during isometric contractions of a human muscle. J Appl Physiol 85:1230–1235PubMedGoogle Scholar
  15. Jones DA, Rutherford OM, Parker DF (1989) Physiological changes in skeletal muscle as a result of strength training. Q J Exp Physiol 74:233–256PubMedGoogle Scholar
  16. Kanehisa H, Miyashita M (1983) Specificity of velocity in strength training. Eur J Appl Physiol 52:104–106CrossRefGoogle Scholar
  17. Komi PV (1984) Physiological and biomechanical correlates of muscle function: effects of muscle structure and stretch-shortening cycle on force and speed. Exerc Sport Sci Rev 12:81–121PubMedCrossRefGoogle Scholar
  18. Komi PV, Bosco C (1978) Utilization of stored elastic energy in leg extensor muscle by men and women. Med Sci Sports 10:261–265PubMedGoogle Scholar
  19. Kubo K, Kawakami Y, Fukunaga T (1999) Influence of elastic properties of tendon structures on jump performance in humans. J Appl Physiol 87:2090–2096PubMedGoogle Scholar
  20. Kubo K, Akima H, Kouzaki M, Ito M, Kawakami Y, Kanehisa H, Fukunaga T (2000a) Changes in the elastic properties of tendon structures following 20 days bed-rest in humans. Eur J Appl Physiol 83:463–468CrossRefGoogle Scholar
  21. Kubo K, Kanehisa H, Kawakami Y, Fukunaga T (2000b) Elastic properties of muscle–tendon complex in long distance runners. Eur J Appl Physiol 81:181–187CrossRefGoogle Scholar
  22. Kubo K, Kanehisa H, Fukunaga T (2001) Effects of different duration isometric contractions on tendon elasticity in human quadriceps muscles. J Physiol 536:649–655PubMedCrossRefGoogle Scholar
  23. Kubo K, Kanehisa H, Fukunaga T (2002a) Effects of resistance and stretching training programs on the viscoelastic properties of tendon structures in vivo. J Physiol 538:219–226CrossRefGoogle Scholar
  24. Kubo K, Kanehisa H, Kawakami Y, Fukunaga T (2002b) Measurement of viscoelastic properties of tendon structures in vivo. Scand J Med Sci Sports 12:3–8CrossRefGoogle Scholar
  25. Kubo K, Kanehisa H, Fukunaga T (2005) Effects of viscoelastic properties of tendon structures on stretch-shortening cycle exercises in vivo. J Sports Sci 23:851–860PubMedCrossRefGoogle Scholar
  26. Maganaris CN, Paul JP (1999) In vivo human tendon mechanical properties. J Physiol 521:307–313PubMedCrossRefGoogle Scholar
  27. Magnusson SP, Aagaard P, Rosager S, Poulsen PD, Kjaer M (2001) Load–displacement properties of the human triceps surae aponeurosis in vivo. J Physiol 531:277–288PubMedCrossRefGoogle Scholar
  28. McCarthy JP, Agre JC, Graf BK, Pozniak MA, Vailas AC (1995) Compatibility of adaptive responses with combining strength and endurance training. Med Sci Sports Exer 27:429–436Google Scholar
  29. Narici MV, Hoppeler H, Kayser B, Landoni L, Claassen H, Gavardi C, Conti M, Cerretelli P (1996) Human quadriceps cross-sectional area, torque and neural activation during 6 months strength training. Acta Physiol Scand 157:175–186PubMedCrossRefGoogle Scholar
  30. Reeves ND, Maganaris CN, Narici MV (2003) Effect of strength training on human patella tendon mechanical properties of older individuals. J Physiol 548:971–981PubMedCrossRefGoogle Scholar
  31. Rollhauser H (1954) Funktionelle Anpassung der Sehnenfaser im submikroskopischen Bereich. Anat Anz 51:318–322Google Scholar
  32. Rosager S, Aagaard P, Dyhre-Poulsen P, Neergaard K, Kjaer M. Magnusson SP (2002) Load–displacement properties of the human triceps surae aponeurosis and tendon in runners and non-runners. Scand J Med Sci Sports 12:90–98PubMedCrossRefGoogle Scholar
  33. Schott J, McCully K, Rutherford OM (1995) The role of metabolites in strength training. II. Short versus long isometric contractions. Eur J Appl Physiol 71:337–341CrossRefGoogle Scholar
  34. Sheehan FT, Zajac FE, Drace JE (1999) In vivo tracking of the human patella using cine phase contrast magnetic resonance imaging. J Biomech Eng 121:650–656PubMedGoogle Scholar
  35. Vailais AC, Tipton CM, Laughlin HL (1978) The influence of physical activity and hypophysectomy on aerobic capacity of ligaments and tendons. J Appl Physiol 44:542–546Google Scholar
  36. Viidik A (1972) Simultaneous mechanical and light microscopic studies of collagen fibers. Z Anat Entwick 136:204–212CrossRefGoogle Scholar
  37. Visser JJ, Hoogkamer JE, Bobbert MF, Huijing PA (1990) Length and moment arm of human leg muscles as a function of knee and hip-joint angles. Eur J Appl Physiol 61:453–460CrossRefGoogle Scholar
  38. Walshe AD, Wilson GJ , Murphy AJ (1996) The validity and reliability of a test of lower body musculotendinous stiffness. Eur J Appl Physiol 73:332–339CrossRefGoogle Scholar
  39. Williams JGP (1986) Achilles tendon lesions in sports. Sports Med 3:114–135PubMedCrossRefGoogle Scholar
  40. Woo SL, Gomez MA, Amiel D, Ritter MA, Gelberman RH, Akeson WH (1981) The effects of exercise on the biomechanical and biochemical properties of swine digital flexor tendons. J Biomech Eng 103:51–56PubMedCrossRefGoogle Scholar
  41. Zajac FE (1989) Muscle and tendon: properties, models, scaling and application to biomechanics and motor control. CRC Crit Rev Biomed Eng 17:359–411Google Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Keitaro Kubo
    • 1
  • Hideaki Yata
    • 2
  • Hiroaki Kanehisa
    • 1
  • Tetsuo Fukunaga
    • 3
  1. 1.Department of Life Science (Sports Sciences)University of TokyoTokyoJapan
  2. 2.Sports Science LaboratoryWako UniversityMachida, TokyoJapan
  3. 3.Department of Sports SciencesWaseda UniversityTokorozawa, SaitamaJapan

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