Table 1.

Reproducibility of M-US parameters of the young and old group. Analysis of variance components with random effect mixed models were calculated to determine inter-day, inter-rater, inter-repetition and inter-subject standard deviations. ICCs were calculated as the ratio of the inter-subject component of variance to the total variance

	Inter-day SD		Inter-rater SD		Inter-repetition SD		Inter-subject SD		ICCs
	Young	Old	Young	Old	Young	Old	Young	Old	Young	Old
Muscle thickness
Musculus rectus femoris	0.14	0.19	0.15	<0.01	<0.01	0.15	3.98	1.88	97.2	87.6
Musculus intermedius	0.21	0.13	0.21	0.25	0.10	0.20	4.35	2.91	97.8	92.8
Musculus vast. lateralis	0.25	0.36	0.20	0.45	<0.01	0.09	3.74	2.39	95.7	85.2
Musculus vast. medialis	<0.01	<0.01	0.11	0.26	0.20	0.26	6.06	4.70	97.9	94.9
Pennation angle
Musculus intermedius	0.23	<0.01	0.22	0.42	<0.01	<0.01	2.53	2.15	78.3	74.1
Musculus vast. lateralis	0.55	0.34	0.54	<0.01	0.63	0.19	2.31	2.45	53.0	68.7
Musculus vast. medialis	0.82	0.66	0.46	0.61	<0.01	0.45	1.70	0.88	43.6	18.9
Echogenicity
Musculus rectus femoris	7.43	14.75	0.72	0.39	<0.01	1.69	12.09	10.91	57.1	30.7
Musculus intermedius	8.36	14.53	4.40	4.27	<0.01	3.28	18.50	12.13	65.0	31.3
Musculus vast. lateralis	6.21	13.10	3.85	3.88	2.22	<0.01	13.36	10.74	62.3	29.7
Musculus vast. medialis	7.37	12.30	1.45	3.97	3.61	1.61	14.99	8.38	62.4	20.9