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. 2018 Oct 1;18(2):301–318. doi: 10.1007/s10237-018-1081-0

Table 2.

Fixed, subject-specific and stochastic parameters of the multiscale model

Fixed parameters
c = 0.554 (Croskey et al. 1922)	∆t = 0.09 s (Laing and Robinovitch 2008)	n = 0.65 (Gillespie et al. 2012)

Parameter (unit)	Fracture group (n = 49)	Non-fracture group (n = 49)
Subject-specific parameters: mean (SD) (Qasim et al. 2016; Yang et al. 2014)
m (kg)	62.6 (14.3)	64.9 (12.1)
H (m)	1.58 (0.0653)	1.58 (0.0592)
Age (years)	75.4 (9.44)	74.7 (8.86)

Parameter (Unit)	Truncation values	Justifications and references
Fall stochasticity parameters
θ_i (°)	a = 0	Falls from upright position (Robinovitch et al. 2013)
θ_i (°)	b = 30	Minimum inclination from which fall recovery is not possible (Smeesters et al. 2001; Thelen et al. 1997; Wojcik et al. 1999).
θ_f (°)	a = 60	Falling on stairs with feet downward (Talbot et al. 2005); typical inclination from the vertical of stairs in the UK (HM Government 2013)
θ_f (°)	b = 120	Falling with feet on chair and hip on ground (Talbot et al. 2005); seat height of standard chair: 44 cm (Wheeler et al. 1985); COM distance from feet for average subject: h = c*1.58 m = 87.5 cm; inclination of pendulum with horizontal = arcsin (44/87.5) ~ 30°
cH ${\dot{θ}}_{i}$ (ms⁻¹)	a = 0.00	Falls from a state of rest (Robinovitch et al. 2013)
cH ${\dot{θ}}_{i}$ (ms⁻¹)	b = 1.40	Falls initiated with highest linear COM velocity achieved during level walk (Robinovitch et al. 2013; Terrier and Reynard 2015)
cH ${\ddot{θ}}_{i}$ (ms⁻²)	a = 0.00	Falls initiated during unaccelerated and the most accelerated phases of gait (Hernandez et al. 2009)
cH ${\ddot{θ}}_{i}$ (ms⁻²)	b = 5.10
η_P (–)	a = 0.500	Based on dynamical models of falling (Sandler and Robinovitch 2001; van den Kroonenberg et al. 1995)
η_P (–)	b = 0.800
η_I (–)	a = − 2.55	(1 − a) ≡ (1 − min η^floor_I)(1 − min η^ext_I)(1 − min η^act_I)
		(1 − b) ≡ (1 − max η^floor_I)(1 − max η^ext_I)(1 − max η^act_I)
		η^floor_I: 0–0.870, based on experiments of Laing and Robinovitch (2009) using synthetic hips without hip protectors (η^act_I = 0, η^ext_I = 0) impacting various flooring materials
	b = 0.914	η^ext_I: 0–0.338, based on experiments of Laing and Robinovitch (2008) considering synthetic hips impacting rigid floors (η^act_I = 0, η^floor_I = 0) with various hip protector designs
		η^act_I: –2.55–0, based on experiments of Robinovitch et al. (1991) conducted on rigid floors without hip protectors (η^floor_I = 0, η^ext_I = 0) with live subjects contracting or relaxing trunk and back muscles during fall