Table 3.

Muscle strength and physical function in the study groups

	Placebo tablets	Vitamin D tablets	Vitamin D × yogurt	Vitamin D	Yogurt	Pb	Pb
	HP yogurt	NP yogurt	HP yogurt	NP yogurt	Pa
Nc	45	49	43	46
Handgrip (kg)
Baseline	11.2 ± 3.0	11.1 ± 3.2	11.9 ± 2.7	11.8 ± 2.5
Endpoint	12.9 ± 2.9	12.6 ± 3.2	13.6 ± 3.1	13.4 ± 2.2		0.1 [-0.3, 0.6]	0.2 [-0.3, 0.6]
Change	1.7 ± 1.6*	1.5 ± 1.6*	1.7 ± 1.6*	1.6 ± 1.4*	P = 0.53	P = 0.64	P = 0.41
Leg press (N)
Baseline	1106 ± 395	1144 ± 403	1188 ± 304	1117 ± 359
Endpoint	1642 ± 411	1654 ± 443	1677 ± 407	1705 ± 383		38 [− 61, 136]	− 29 [− 128, 69]
Change	536 ± 368*	510 ± 385*	489 ± 337*	588 ± 348*	P = 0.27	P = 0.58	P = 0.55
Squat jump (cm)
Baseline	19.9 ± 4.4	18.9 ± 4.5	18.5 ± 4.0	19.7 ± 3.6
Endpoint	20.0 ± 4.1	19.2 ± 5.2	19.8 ± 3.5	20.1 ± 3.2		0.5 [− 0.4, 1.4]	0.5 [− 0.4, 1.4]
Change	0.1 ± 3.1	0.2 ± 2.5	1.3 ± 2.6*	0.4 ± 2.5	P = 0.70	P = 0.29	P = 0.29
Long jump (cm)
Baseline	122 ± 16	115 ± 24	120 ± 17	121 ± 17
Endpoint	128 ± 18	122 ± 19	124 ± 19	124 ± 14		− 2.0 [− 5.0, 1.1]	0.4 [− 2.6, 3.5]
Change	5 ± 9*	7 ± 11*	4 ± 7*	3 ± 10*	P = 0.63	P = 0.20	P = 0.78
30 s sit-to-stand (repetitions)
Baseline	33 ± 5	31 ± 5	32 ± 5	32 ± 4
Endpoint	37 ± 4	34 ± 5	35 ± 4	36 ± 4		0.6 [− 0,8, 2.0]	0.5 [− 0.9, 1.8]
Change	4 ± 4*	3 ± 5*	3 ± 3*	4 ± 5*	P = 0.023	P = 0.38	P = 0.51

Values are presented as mean ± SD. All complete cases are included. *Significant within-group changes (P < 0.05), tested by paired t test

HP high protein, LM lean mass, NP normal protein

^aP values are from the treatment interaction term in two-way ANCOVA models adjusted for baseline of the outcome

^bP values are from main effects of vitamin D and dairy protein, respectively, obtained from additive two-way ANCOVA models adjusted for baseline of the outcome

^cn represent maximal number. For leg press, n = 44, n = 49, n = 43, and n = 46; for squat jump, long jump, and 30 s sit-to-stand, n = 29, n = 33, n = 29, and n = 31 in the placebo-HP, placebo-NP, vitamin D-HP, and vitamin D-NP group, respectively