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Table 3 Subgroup analyses of the effects of protein intake on muscle strength

From: Synergistic Effect of Increased Total Protein Intake and Strength Training on Muscle Strength: A Dose-Response Meta-analysis of Randomized Controlled Trials

 

RT

Non-RT

All

 

N/study

MD (95% CI) (%)

I2 (%)

N/study

MD (95% CI) (%)

I2 (%)

N/study

MD (95% CI) (%)

I2 (%)

All

2440/59

2.01 (1.09, 2.93)

16

1500/24

0.13 (− 1.53, 1.79)

49

3940/82

1.40 (0.55, 2.24)

32

Subgroup analysis

Age (years)

 < 60

1461/37

2.35 (1.00, 3.69)

27

81/2

0.95 (− 4.97, 6.86)

46

1542/39

2.25 (0.95, 3.54)

27

 ≥ 60

923/22

1.38 (0.39, 2.36)

0

1389/21

0.20 (− 1.65, 2.04)

53

2312/42

0.64 (− 0.47, 1.75)

35

Sex

 Female

403/13

1.54 (0.46, 2.62)

0

292/5

2.48 (− 5.43, 10.39)

74

695/18

1.38 (− 0.28, 3.04)

28

 Male

1078/33

2.07 (0.71, 3.43)

9

105/3

− 0.95 (− 3.51, 1.60)

0

1183/35

1.64 (0.37, 2.91)

13

Baseline protein intake (g/kg BW/d)

 < 1.0

561/12

1.46 (0.45, 2.48)

0

314/6

− 0.26 (− 2.56, 2.03)

20

875/18

1.06 (− 0.01, 2.13)

11

 ≥ 1.0

1235/31

2.11 (0.76, 3.46)

0

962/13

− 0.81 (− 3.00, 1.38)

51

2197/43

0.93 (− 0.35, 2.21)

32

Added protein intake (g/kg BW/d)b

  < 0.5

1849/45

1.22 (0.41, 2.03)

0

1056/18

1.38 (− 0.95, 3.71)

57

2905/63

1.10 (0.17, 2.03)

22

 ≥ 0.5

538/14

4.29 (1.99, 6.60)

40

356/6

− 1.64 (− 3.52, 0.25)

0

894/19

2.36 (0.35, 4.37)

55

Trial periods (months)a

 < 3

1845/50

2.27 (1.23, 3.30)

19

719/15

0.95 (− 1.56, 3.46)

53

2564/64

1.90 (0.91, 2.90)

31

 ≥ 3

595/9

0.66 (− 1.22, 2.54)

0

781/9

− 0.67 (− 2.84, 1.50)

44

1376/18

− 0.05 (− 1.52, 1.43)

26

Contraction type

 Isokinetic

370/7

0.71 (− 4.69, 6.11)

59

217/3

− 1.11 (− 5.25, 3.03)

45

587/10

− 0.03 (− 3.53, 3.47)

54

 Isometric

892/18

0.92 (− 0.33, 2.17)

7

1439/22

0.26 (− 1.70, 2.23)

60

2331/39

0.33 (− 0.91, 1.56)

47

 Isotonic

1989/49

2.30 (1.25, 3.36)

21

191/6

0.57 (− 1.99, 3.13)

0

2180/54

2.13 (1.16, 3.11)

19

Body part

 Upper body

1570/44

1.39 (0.25, 2.54)

52

1252/20

0.15 (− 1.65, 1.95)

59

2822/63

0.99 (0.01, 1.98)

56

 Lower body

1898/50

2.77 (1.46, 4.07)

39

853/15

0.40 (− 1.82, 2.62)

24

2751/64

2.21 (1.07, 3.34)

38

  1. RT resistance training, MD mean difference, BW body weight
  2. aStatistically significant difference subgroups in the analysis of all trials (P < 0.05)
  3. bStatistically significant difference subgroups in the analysis of trials with RT (P < 0.05)
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