Running and the Stress Strain Relationship

The Stress-Strain Relationship Many factors lead to any of us sustaining an overuse injury. One of the main factors is Impact force. When we run these impact forces are repeated and can build up over time. This increases its potential for injury. This force is the Ground reaction force (GRF) which is 2-3 times our bodyweight. 5Km Run 3000 Impacts Yield Point Plastic Limit Why? Stress The impacts of running begin to build up in the Injury occurs body and this causes more stress and strain to be applied. Strain Stress= external force that deforms bodies tissues Excess Stress/Strain ! Strain= Puts a number on stress (%). It measures the amount of deformation that Stress/Strain can build up and can be dealt with up until the point where our tissues wont stretch any more, the yield point. if more stress is applied then the tissue will deform to its plastic limit. Injury and rupture occur at this point. stress causes Stress-Strain Relationship= They are related linearly, as 1 increases so does the other. This is In the above graph you can see these limits. The elastic region is a region where the tissues can tolerate the deformation caused be stress. The plastic region is where deformation is occurring and some permanent damage is done, but tissues can still return to normal. Hooke's Law. Our bodies can deal with Stress and Strain up to a certain point and even has ways of dissipating the impact forces through attenuating mechanisms such as using cartilages, tendons and muscles. References: Hall, S. (1990) Basic Biomechanics, Boston, McGraw-Hill 2.Taunton et al (2002) A retrospective case-control analysis of 2002 running injuries. British Journal of Sports Medicine; Vol 36, 95-101 3. Hreljac et al. (2000) Evaluation of lower extremity overuse injury potential in runners, MSSE Vol 32(9): 1635-1641 4. Shorten, M.R., Winslow, D.S, (1992) Spectral analysis of impact shock during running, International journal of sport Biomechanics, Vol 8 (4) 5. McGinnis, P.M, (2013) Biomechanics of Sport and Exercise 3rd ed, Human kinetics, Auckland. 6. Pratt, D., (1989) mechanisms of shock attenuation via the lower extremity during running, Clinical biomechanics, Vol 4(1) Pp. 51-57 www.FitnessCluster.com Elastic region Plastic region