Powered ankle-foot orthoses: the effects of the assistance on healthy and impaired users while walking

Table 8 Comparison of the effects of different assistance magnitude on the user’s effort during level walking

Ref.	Assistance magnitude		Metabolic cost w.r.t. U	Soleus activation w.r.t. U
Galle, 2017 [21] ♢	double pos.	0.21 W/kg	-(14%-18%)	reduced with increased power level (peak)
		0.41 W/kg	-(16%-21%)
		0.50 W/kg	-(16%-17%)
Jackson, 2015 [20] □	net	-0.05 W/kg	+5%	-9% (rms)
		0 W/kg	0%	-14%
		0.09 W/kg	-9%	-32%
		0.18 W/kg	-17%	-36%
		0.25 W/kg	-17%	-45%
Mooney, 2014 [48] ⋈	pos.	0.15 W/kg	-14%	/
Mooney, 2016 [49] ⋈	pos.	0.1 W/kg	-14%	/
Sawicki, 2008 [36] △	pos.	0.24 W/kg	-15%	-18% (rms)
Sawicki, 2009 [37] △	pos.	0.17-0.23 W/kg	-(8%-12%)	-(11%-20%) (rms)
Sawicki, 2009 [38] △	pos.	0.23 W/kg	-13%	-25% (rms)

The assistance magnitude is defined as the average power provided by the PAFO per stride. The effects on the metabolic cost and soleus activity of powered walking are reported with respect to the unpowered condition (U). The results of the study by Sawicki et al. [38] are reported only for level walking. Jackson et al. [20] studied the effects of net assistance magnitude, however, for positive levels the negative average power is negligible, thus, their results can be compared to the ones of the other studies. Galle et al. [21] assessed the effects of the double positive assistance magnitude, i.e. the sum of the assistance magnitude for the two legs. Regarding the results of the soleus activation, the table reports whether the peak or the rms values are considered in the different studies
Symbols (♢,□,⋈,△) indicate studies performed by the same research group on similar actuation setups. Symbols are consistent between tables. In the works in which different experiments were performed (for example, different levels of assistance magnitude) the common information between the experiments (for example, same type of assistance magnitude) is reported only once

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