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  • Level: GCSE
  • Subject: Maths
  • Word count: 4203

The effect of drop jump height on spinal shrinkage.

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The effect of drop jump height on spinal shrinkage

Advanced Biomechanics 2002

Author: D. Hinchley


        The aim of this study was to determine the effect of drop jump height on spinal shrinkage. 5 male subjects of mean (age 21 +/- 1.2 years, height 181 +/- 6.3 cm, body mass 78 +/- 8kg) all with previous experience of plyometric training participated in this study. Subjects performed 2 regimens of 5 standing drop jumps from a height of 35cms (block1) and a second height of 70cm (block2), onto a force platform from which an immediate rebound jump was performed. Both regimens were conducted at the same time of day and separated by 1 week.  Prior to each regimen subjects adopted the fowler position, stature was recorded prior to and proceeding each regimen.  Joint centre markers were placed on the following anatomical positions:   1). Ankle, 2). Knee, 3). Hip, 4). Shoulder. Both trials were captured on video and analysed using the digiTEESer software programme, from this peak hip velocity was calculated for each subject and regimen.  A one-way ANOVA was undertaken to compare the differences in peak ground reaction force, peak hip velocity, and stature change between the 2 regimes.  Following this the data was analysed using linear regression to establish the relationships between peak ground reaction force, peak hip velocities, and stature change.  The analysis found significant differences (P < 0.05) between regimes for both stature change and peak hip velocity, but not for peak ground reaction force (P > 0.05).  Significant relationships (P < 0.05) were found between block height for peak hip velocity and stature change, no significant relationship (P > 0.05) was found between block height and peak ground reaction force, and stature change for peak hip velocity and peak ground reaction force. The study concluded drop jump height significantly affects levels of spinal shrinkage.  


The human spine is separated into 5 sections.

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The video images were displayed and digitised using the DigeTEESer software programme. The joint centre markers were located on the screen and their centre was digitised.

Each point was digitised from when the toe left the box on the initial jump phase to when the toe was about to leave the force reaction platform on the jump up to the second box. DigiTEESer provided kinematic data for all the joints marked this data was then smoothed using a five point moving average. From this data peak hip velocity for each subject was calculated using the formula difference in hip vertical position/difference in time. A one way ANOVA was used to determine if any differences lie between block height and PGRF, PHV and stature change. Linear regression was used to determine if there was any significant relationship between the aforementioned factors.


Table 1 indicates a block height comparison of subjects’ peak hip velocities (m/s-1) and peak ground reaction forces (N) reported in both drop jump regimens. Table 1 also shows the resultant stature change comparison between block heights reported immediately after the completion of each drop jump regimen.

Table 1: A drop jump height comparison of Peak Hip Velocity, Peak Ground Reaction Force and Stature Change


Peak Hip






































































Figure 1: A mean and SD comparison of drop jump heights for peak hip velocities (m/s-1)

Figure 1 indicates the effect of which block height incurred upon the subjects’ peak hip velocities.  A one-way analysis of variance revealed a significant main effect for block height on PHV reporting; F 1, 9 = 53.69,            P < 0.01.

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 Medicine and Science in Sports and Exercise,31, 708-16.

Koller, W., Funke, F. and Hartman, F. (1984). Biomechanical behaviour of human intervertebral discs subjected to long lasting axial loading. Biorheology, 21, 675-86.

Kovacs, I., Tihanyi, J., Devita, P., Racz, L., Barrier, J. and Hortobagyi, T. (2000). Foot placement modifies kinematics and kinetics during drop jumping. Medicine and Science in Sports and Exercise,32, 1833-44.

Kramer, J., Kolditz, D. and Gowein, R. (1985). Water and electrolyte content of human intervertebral discs under variable load. Spine, 10, 69-71.

Leatt, P., Reilly, T. and Troup, J.D.G. (1986). Spinal loading during circuit weight-training and running. British Journal of Sports Medicine,20, 119-24.

Markolf, K.L. (1972). Deformation of the thoracolumbar intervertebral joints in response to external loads. Journal of Bone and Joint Surgery, 54A, 511-33.

McNitt-Gray, J.L. (1993). Kinetics of the lower extremities during drop landings from three heights. Journal of Biomechanics,26, 1037–46.

Porterfield, J.A. and DeRosa, C. (1998). Mechanical Low Back Pain: Perspectives in Functional Anatomy: Second Edition. Philadelphia: W.B. Saunders.

Reilly, D.T. (1988). Dynamic loading of normal joints. Rheumatic Disease Clinic of North America, 14, 497-502.

Reilly, T. Tyrell, A. and Troup, J.D.G. (1984). Circadian variation in human stature. Chronobiology International, 1, 121-6.

Troup, J.D.G. (1965). Relation of lumbar spine disorders to heavy manual work and lifting. Lancet, 17, 857-61.

Tyrell, A.R., Reilly, T. and Troup, J.D.G. (1985). Circadian variation in stature and the effects of spinal loading. Spine, 10, 161-4.

Van Dieen, J.H., Creemers, M., Draisma, I. and Toussaint, H.M. (1994). Repetitive lifting and spinal shrinkage, effects of age and lifting techniques. Clincal Biomechanics, 9, 61-3.

Van Dieen, J.H. and Toussaint, H.M. (1993). Spinal shrinkage as a parameter of functional load. Spine, 18, 1504-14.

Wilby, J., Linge, K., Reilly, T. and Troup, J.D.G. (1987). Spinal shrinkage in females: circadian variation and the effects of circuit weight training. Ergonomics, 30, 47-54.

Zhang, S.N., Bates, B.T. and Dufek, J.S. (2000). Contributions of lower extremity joints to energy dissipation during landings. Medicine and Science in Sports and Exercise,32, 812-9.

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