. 2020 Jun 23;11:716. doi: 10.3389/fphys.2020.00716

TABLE 1.

This table summarizes the observable effects.

	Dry immersion	Wet immersion	Unilateral lower limb suspension	Head down tilt	Supine bed rest
Mimics cardiovascular effects of space flight	***	**	*	***	**
Mimics musculoskeletal loss of space flight	**	*	***	***	***
Feasibility of maintaining position	**	*	*	***	***
Median duration	3–7 days	4 h	30 days	30 days	30 days
Maximum duration	56 days^13.14	12 h^13.14	42 days^13.6	370 days^13.14

* is used to indicate weak comparability, ** is used to indicate moderate comparability, and *** indicates strong comparability. Feasibility of Maintaining Position includes the physical stress placed upon the subject as well as the costs and logistics involved. ^13.6is a reference to Hackney and Ploutz-Snyder (2011), ^13.14is a reference to Navasiolava et al. (2010).