Table 3.

Knee extensor muscle group regression equation, model parameters, diagnostic statistics, group characteristics (mean ± standard deviation), and between-session reliability of ultrasound measurements

Equation: $\text{Knee extensor muscle volume}=996.168+\left(4.664\times \text{anterior thigh muscle thickness at}50\%\text{of thigh length}.\text{body mass}\right)$
	β	Standard error (lower limit – upper limit)	p value
Constant	996.168	257.349 (429.747–1562.588)	0.003
Anterior thigh muscle thickness at 50% of thigh length.body mass	4.664	0.905 (2.673–6.655)	< 0.001
R2	0.707
Adjusted R2	0.681
Standard error of the estimate (cm3)	121.10 (5.24%)
Mean cross-validation residual (cm3)	20.11 (0.95%)
Durbin–Watson statistic	2.32

	Model-development group	Cross-validation group (range)	Between-session difference (TEM)
Height (m)	1.81 ± 0.07	177.1 (171.5–181.2)
Body mass (kg)	78.2 ± 8.2	72.7 (65.7–80.5)
Thigh length (m)	0.42 ± 0.04	0.41 (0.39–0.43)
Anterior thigh muscle thickness at 50% of thigh length (cm)	3.6 ± 0.4	3.7 (3.0–4.4)	0.1 (2.0%)
Knee extensor muscle volume (cm3)	2311.6 ± 214.3	2110.32 (1809.1–2302.9)

Model-development group n = 13, cross-validation group n = 3