Table 1.

Definition of variables used in analyses.

Variable	Symbol	Description
Finger compression force	Ff	Mean compression force during the hold phase of the SD test (units: gf)
Finger force velocity	${\dot{F}}_f$	Mean of the absolute value of the first time derivate of compression force during the hold phase of the SD test (units: gf/s)
Finger force acceleration	${\ddot{F}}_f$	Mean of the absolute value of the second time derivate of compression force during the hold phase of the SD test (units: gf/s2)
Finger force RMS	RMSf	Magnitude of the mean of the force dispersions during the hold phase of the SD test (units: gf)
Leg compression force	Fl	Mean compression force during the hold phase of the LED test (units: N)
Leg force velocity	${\dot{F}}_l$	Mean of the absolute value of the first time derivate of compression force during the hold phase of the SD test (units: N/s)
Leg force acceleration	${\ddot{F}}_l$	Mean of the absolute value of the second time derivate of compression force during the hold phase of the SD test (units: N/s2)
Leg force root-mean square (RMS)	RMSf	Magnitude of the mean force dispersions during the hold phase of the SD test (units: N)

Note that force magnitudes for the finger and leg tasks (cf. Figures 1 and 2) are two orders of magnitude apart. Therefore, we use the SI units of gf and N, respectively, to accommodate those differences.