Table 1.

Definition and interpretation of recurrence quantification analysis (RQA) and detrended fluctuation analysis (DFA) in the context of the balance task.

	Variable	Definition	Higher value interpretation	Lower value interpretation
RQA diagonal	%DET	The percentage of all recurrences in phase space (below a pre-set threshold distance) that form diagonal line lengths longer than 100 ms	More predictable, more deterministic, less random CoP motion, consistent with better balance performance	Less predictable, less deterministic, more random CoP motion, consistent with reduced balance performance
	Lmean	The mean length of the diagonal lines in the recurrence plot	Better balance performance, less impact of small perturbations resulting in more similar temporal dynamic CoP patterns	Reduced balance performance, greater impact of small perturbations, resulting in less similar (more random) temporal dynamic CoP patterns
RQA vertical	%LAM	The percentage of all recurrences in phase space (below a pre-set threshold distance) that form vertical line lengths longer than 100 ms	More intermittent CoP motion with more periods of minimal CoP fluctuations	Less intermittent CoP motion with fewer periods of minimal CoP fluctuations
	TT	The mean length of the vertical lines in the recurrence plot	Longer periods of minimal CoP fluctuations (static states)	Shorter periods of minimal CoP fluctuations (static states)
DFA	DFA1	Exponential interrelation of CoP fluctuations at time scales between 0.1 and tau s	Smoother and more persistent CoP motion at time scales < tau	Less smooth and less persistent CoP movements at time scales < tau
	DFA2	Exponential interrelation of CoP fluctuations at time scales between tau and 4.42 s	Smoother and less anti persistent CoP motion at time scales > tau	Less smooth and more anti persistent CoP motion at time scales > tau
	DFAtau	The time scale that separates DFA short and DFA long	Less conservative balance control	More conservative balance control

Recurrence quantification analysis (RQA), diagonal line structures; percentage determinism (%DET), mean diagonal line length (L_mean), vertical line structure; percentage laminarity (%LAM), mean vertical line length (trapping time, TT). Detrended fluctuation analysis (DFA), short term DFA (DFA₁), longer term DFA (DFA₂) and the time scale that separates DFA₁ and DFA₂; DFA_tau.