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Table 2 Summary of the characteristics of the included studies

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
Number of studies 59 24 82
Number of participants 2440 1500 3940
Age (years) 45.5 72.1 55.6
 Number of participants aged 19–59 1461 81 1542
 Number of participants aged 60–87 923 1389 2312
Sex (men %) 62 38 53
Race (Caucasian %) 88 63 78
Height (cm) 171 164 168
 Number of participants (149–169 cm) 768 1022 1790
 Number of participants (170–185 cm) 1460 329 1789
Body weight (kg) 78.8 68.1 74.8
 Number of participants (46–74 kg) 672 977 1649
 Number of participants (75–102 kg) 1631 395 2026
Body mass index (kg/m2) 26.6 25.4 26.1
 Number of participants (20.6–24.9 kg/m2) 768 516 1284
 Number of participants (25.0–37.9 kg/m2) 1597 963 2560
Energy intake (kcal/day) 2141 1752 2035
 Number of participants (1298–1999 kcal/day) 561 418 979
 Number of participants (2000–3539 kcal/day) 819 100 919
Baseline protein intake (g/kg BW/d) 0.39 0.37 0.38
 Number of participants (0.60–0.99 g/kg BW/d) 561 314 875
 Number of participants (1.00–2.10 g/kg BW/d) 1235 962 2197
Added protein intake (g/kg BW/d) (intervention groups) 0.39 0.37 0.38
 Number of participants (0.04–0.49 g/kgBW/d) 1036 582 1618
 Number of participants (0.50–2.06 g/kgBW/d) 274 212 486
Total protein intake (g/kg BW/d) (intervention groups) 1.50 1.46 1.49
 Number of participants (0.79–1.49 g/kgBW/d) 708 393 1101
 Number of participants (1.50–3.80 g/kgBW/d) 472 311 783
Trial periods (weeks) 15.1 33.3 22.0
 Number of participants (3 weeks to 2.9 months) 1845 719 2564
 Number of participants (3 months to 2 years) 595 781 1376
Habitual training (%) 13 0 8
Body part    
 Upper body (%) 64 83 72
 Lower body (%) 78 57 70
Contraction type    
 Isokinetic (%) 15 14 15
 Isometric (%) 37 96 59
 Isotonic (%) 82 13 55
  1. Data are shown as the mean values weighted by the number of participants
  2. RT resistance training, BW body weight