Very interesting indeed. Although in the end the formula provided is nothing else than Force x Total Time Under Tensions; I doubt it works really that way (at least in PE), pulling with 60 lbs for 10 hour isn’t the same than pulling with 6lbs for 100 hours.
Checking the references, I found this
“THE MUSCULAR FLEXIBILITY TRAINING AND THE RANGE OF
MOVEMENT IMPROVEMENT: A CRITICAL LITERATURE REVIEW”
Luís Filipe dos Santos Coelho1
1 Fisioterapeuta e Professor de Pilates
do Consultório e Clínica de Reabilitação, Lda.
where the formula is adjusted with the elasticity coefficient
“The visco-elastic behavior of the soft fabrics during an elongation is composed of a deformation or creep, expressing more precisely the muscular fluage. Such a muscular behavior can be expressed by the following equation
INDEX OF DEFORMATION = APPLIED FORCE / COEFFICIENT OF ELASTICITY X TIME
the muscular deformation will be larger in muscles with smaller Coefficient of elasticity and it will be proportionally dependent of the applied Force and of the factor Time.”
Again though this doesn’t add much.
Anyway since the paper you linked is free in the public domain, I’ll upload it here.