# Computation of Soft Tissue energy dissipation (PST,Kuo) as in Riddick & Kuo (2022) from Relation between soft tissue energy dissipation and leg stiffness in running at different step frequencies

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posted on 2024-06-03, 15:46 authored by Arthur H Dewolf, André Ivaniski-Mello, Leonardo Alexandre Peyré-Tartaruga, Raphael M. MesquitaA different method can be used for calculating the energy dissipation done by soft-tissue deformation over a step (EST,kuo), as seen in Riddick & Kuo [16,17]. These last authors consider the difference between total power (Ptot) and joint power (Pj) as the rate of energy dissipation done by the soft tissue deformation, P_(ST,Kuo)= P_tot-P_j. Total power is the sum of external (Pext) and internal power (Pint) over one step, where the former, Pext, is based on the product of the force and velocity as in Donelan et al. [34] and the latter, Pint, is calculated as the sum of the internal energy derivatives of all four limbs and trunk movements as compared to the CoM over one step: P_int=∑_i▒E_(i,int)/dt. In this second method of calculating Pint, energy transfer is allowed for between all considered segments. Accordingly, EST,Kuo is given by: E_(ST,Kuo)=∫▒P_(ST,Kuo) dt and the positive/negative increments of this curve give the work values dissipated by soft tissue deformation, 〖W_(ST,Kuo)〗^(+/-) (Fig. S1). The results obtained with the Riddick and Kuo's methods are the following: the 〖W_(ST,Kuo)〗^+ has no speed effect (F = 0.937, p=0.440) and decreases with frequency (F = 25.931, p<0.001). The Bonferroni post-hoc shows its only different at the lowest frequencies. As of, 2.8Hz there are no more differences (p=1). Bonferonni all the same for speeds. The 〖W_(ST,Kuo)〗^- increases with speed (F = 11.61, p<0.001) and but does not change with frequency (F =2.2, p=0.073).