Table 2.

Results of the piecewise regression analysis for all field tests

Variable	Intercept	Age	Sex	Age 60+	Age-by-sex	Age 60+-by-sex	R²
HGS							0.08
β	100.38***	-0.17n.s.		-0.56*
CI	[94.23; 106.53]	[-0.37; 0.02]		[-1.08; -0.04]
SE	3.13	0.10		0.27
CMJ							0.48
β	105.53***	-0.70***		-0.91***
CI	[100.13; 110.92]	[-0.87; -0.53]		[-1.37; -0.45]
SE	2.74	0.09		0.23
STSP							0.31
β	106.68***	-0.52***
CI	[103.13; 110.24]	[-0.61; -0.44]
SE	1.81	0.04
SCP							0.59
β	105.83***	-0.81***		-0.94***
CI	[100.97; 110.70]	[-0.97; -0.66]		[-1.35; -0.53]
SE	2.47	0.08		0.21
MGS							0.19
β	100.17***	-0.13n.s.		-0.83***
CI	[95.65; 104.69]	[-0.27; 0.02]		[-1.21; -0.45]
SE	2.30	0.07		0.20
TUG							0.44
β	105.67***	-0.45***	-3.31n.s.	-0.35n.s.	0.27*	-0.81**
CI	[99.96; 111.39]	[-0.62; -0.27]	[-10.45; 3.82]	[-0.80; 0.10]	[0.04; 0.49]	[-1.41; -0.22]
SE	2.91	0.09	3.63	0.23	0.11	0.30

HGS = handgrip strength; CMJ = countermovement jump; STSP = sit-to-stand power; SCP = stair-climbing power; MGS = maximal gait speed; TUG = timed-up-and-go; β = regression coefficient; CI = confidence interval; SE = standard error; R² = coefficient of determination; Age = age (years); Age 60 + = age (years) – 60 (for age >60) or 0 (for age ≤60); Sex: male = 0, female = 1; ^***p < 0.001; ^**p = 0.01; ^*p = 0.05; n.s. = p > 0.05