Ground Reaction Forces Associated with an Effective Elementary School based Jumping Intervention

McKay, H., Tsang, G., Heinonen, A., MacKelvie, K., Sanderson, D. and Khan, K. M. (2005) Ground Reaction Forces Associated with an Effective Elementary School based Jumping Intervention. British Journal of Sports Medicine, 39 1: 10-14. doi:10.1136/bjsm.2003.008615

Author McKay, H.
Tsang, G.
Heinonen, A.
MacKelvie, K.
Sanderson, D.
Khan, K. M.
Title Ground Reaction Forces Associated with an Effective Elementary School based Jumping Intervention
Journal name British Journal of Sports Medicine   Check publisher's open access policy
ISSN 0306-3674
Publication date 2005
Sub-type Article (original research)
DOI 10.1136/bjsm.2003.008615
Volume 39
Issue 1
Start page 10
End page 14
Total pages 5
Place of publication England
Publisher BMJ Publishing Group
Language eng
Subject 1106 Human Movement and Sports Science
Abstract Background: Mechanical loading during childhood plays a critical role in normal growth and development of the skeleton. Ground reaction forces (GRFs) may provide a surrogate measure for the strain experienced by bone on landing and at take off. However, there appear to be no paediatric studies that assess GRFs across a variety of loading activities. Objectives: To measure biomechanical variables in commonly performed childhood activities used in an elementary physical education intervention study which augmented bone health in boys and girls. Methods: Maximal GFR, maximal rates of force, and time to maximum force were measured for 12 different jumping activities on a force platform. The jumps measured were drop jumps from 10, 30, and 50 cm, all followed by a plyometric jump, submaximal and maximal jumping jacks, alternating feet jump, counter movement jumps, and side to side jumps over 10 and 20 cm foam barriers. The subjects were 70 children (36 boys and 34 girls), 8.3–11.7 years old. Results: Subjects ranged in height from 128.4 to 172.6 cm and had a mass of 25.0–57.0 kg. Mean (SD) for vertical jump was 24.2 (5.5) cm and 135.2 (16.6) cm for standing long jump. The children engaged in loaded physical activity 5.7 (5.3) hours a week, on average. The highest mean maximal GRFs, normalised for body weight (BW), were generated from the plyometric portion of the drop jumps and the counter movement jump (about 5 times BW) compared with 3.5 times BW for jumping jacks. Similarly, the highest rates of change in force were 514 times BW/s for the drop jump from 10 cm and 493 times BW/s for the counter movement jump. Conclusions: Simple jumps requiring minimal equipment produce GRFs of 3.5–5 times BW and rates of force of around 500 times BW/s. As children appear to attenuate higher impact forces when jumping from increased heights, it cannot be assumed that merely increasing the height of the jump will necessarily ‘‘progress’’ the exercise intervention
Keyword bone health
ground reaction forces
physical activity
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Human Movement and Nutrition Sciences Publications
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