Ground Reaction Force

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Ground Reaction Force When the foot strikes the ground, a force called ground reaction force is created. As shown in the graph below two peaks can be created in a vertical ground reaction force curve; an impact force and active force peak. An impact force occurs usually in “heel to toe” running where the heel strikes the ground first and can be absent in forefoot running where quite often only an active force peak is created. Rearfoot striking is more common in running at slower speeds according to Doherty, 1971 (cited in Cavanagh, 1980), as most runners are in a supinated foot position and adducted hip position during the swing phase of running (Cavanagh, 1980). Impact forces according to Messier et al. (1991) have been implicated in the risk…show more content…
A study by Edwards (2008) found higher peak internal loading at tibial sites in which stress fractures can frequently occur. The two are often grouped together, however, external loading does not necessarily affect internal loading of joint and bone structures (Cole and Nigg, 1995). As mentioned, force up to 2.5 time body weight can be experienced at ground impact yet forces from 8 to 15 times body weight can be experienced at joint contact during the stance phase of running (Rooney, 2011). Internal joint loading is due to a combination of joint reaction force and muscle force although there is a relationship between ground reaction force and internal forces, as peak loads at a joint can result from the combined effects of ground reaction force and active muscle forces (Scott and Winter, 1990). The influence of muscle forces on ground reaction force has been investigated but focus has rarely turned towards the influence of muscles on impact loading of joints. Cole, Nigg and Gerritsen (YEAR) have studied this and found that muscles can influence the control of body segments and ???? max vertical ground reaction force. READ STUDY. Internal joint contact forces are at their maximal during the stance phase of running during propulsion when the muscle activity is at its greatest (Rooney, 2011). Much research has concluded that the impact peak element of ground reaction force correlates to injury SECTION NUMBER but Sasimontonkul et al (YEAR) and Scott and Winter (1990) report active peaks at midstance show the highest internal

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