Table 3.
Excluded studies from meta-analysis due to confounding factors
| Study | N | Age, years (mean ± SD) | Duration | Testing modality | Sets (reps) | Days trained per week | Frequency per week | Pre- vs. post-intervention kg, mean ± SD |
Pre- vs. post-intervention strength difference kg (% change) |
p value (pre vs. post) | ES |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Gomes et al. [20] | 12 11 |
25.5 (± 1.25) 27.1 (± 1.85) |
8 weeks | Sq | 5–10 (8–12) | 1 5 |
LF HF |
132.9 ± 28.0 vs. 140.9 ± 25.5 123.3 ± 17.5 vs. 135.3 ± 22.2 |
8 (6.02) 12 (9.73) |
0.47 0.17 |
0.30 0.60 |
| Gomes et al. [20] | 12 11 |
25.5 (± 1.25) 27.1 (± 1.85) |
8 weeks | BP | 5–10 (8–12) | 1 5 |
LF HF |
103.5 ± 15.4 vs. 109.1 ± 18.5 100.6 ± 14.5 vs. 110.3 ± 12.1 |
5.6 (5.41) 9.7 (9.64) |
0.43 0.10 |
0.33 0.73 |
| Serra et al. [21] | 26 32 16 |
35.3 (± 1.75) 34 (± 2) 34.85 (± 0.85) |
3 months | WG PullD | 3 (10–20) | 2 3 4 |
MF HF HF |
42.6 ± 20.7 vs. 48.5 ± 20.7 44.4 ± 13.9 vs. 51.3 ± 13.9 40.6 ± 20.3 vs. 48.6 ± 21.8 |
5.9 (13.8) 6.9 (13.5) 8 (16.5) |
≤ 0.001 a ≤ 0.001a ≤ 0.001a |
0.29 0.50 0.38 |
| Serra et al. [21] | 26 32 16 |
35.3 (± 1.75) 34 (± 2) 34.85 (± 0.85) |
3 months | CP | 3 (10–20) | 2 3 4 |
MF HFe HF |
41.2 ± 25.6 vs. 49.9 ± 30.2 46.6 ± 20.8 vs. 59.7 ± 25.1 42.1 ± 27.9 vs. 55.6 ± 36.2 |
8.7 (21.1) 13.1 (28.1) 13.5 (32.1) |
≤ 0.001a ≤ 0.001a ≤ 0.00a |
0.31 0.57 0.42 |
| Serra et al. [21] | 26 32 16 |
35.3 (± 1.75) 34 (± 2) 34.85 (± 0.85) |
3 months | LP | 3 (10–20) | 2 3 4 |
MF HFe HF |
108.9 ± 49.1 vs. 128.9 ± 54.5 120.2 ± 48.0 vs. 149.0 ± 57.7 128.8 ± 55.4 vs. 168.1 ± 89.0 |
20 (18.4) 28.8 (24.0) 39.3 (30.5) |
≤ 0.001a ≤ 0.001a ≤ 0.001a |
0.39 0.54 0.53 |
| Yue et al. [23] | 9 9 |
28 (± 7.9) 21 (± 3.2) |
6 weeks | Sq | 4 (8–12) 2 (8–12) |
2 4 |
MF HF |
103 ± 27 vs. 115 ± 34 90 ± 9 vs. 103 ± 13 |
12 (11.7) 13 (14.4) |
≤ 0.001a ≤ 0.001a |
0.39 1.16 |
| Yue et al. [23] | 9 9 |
28 (± 7.9) 21 (± 3.2) |
6 weeks | BP | 4 (8–12) 2 (8–12) |
2 4 |
MF HF |
77 ± 27 vs. 88 ± 30 70 ± 17 vs. 81 ± 15 |
11 (14.3) 11 (15.7) |
≤ 0.001a ≤ 0.001a |
0.39 0.69 |
| Carpenter et al. [34] | 10 12 12 7 |
31(± 31) | 20 weeks | LumExt | 1 (8–12) | 0.5 2 3 4 |
LF MF HF HF |
73.6 ± 24.7 vs. 98.2 ± 32.8 58.9 ± 18.0 vs. 86.2 ± 28.0 69.9 ± 27.5 vs. 105.9 ± 40.8 78.2 ± 21.4 vs. 115.8 ± 31.3 |
24.6 (33.4) 27.3 (46.3) 36 (51.5) 37.6 (48.1) |
≤ 0.05b ≤ 0.05b ≤ 0.05b ≤ 0.05b |
0.85 1.16 1.03 1.40 |
| Pollock et al. [35] | 14 19 |
26 (± 9) 30 (± 9) |
12 weeks | CervExt | 1 (8–12) | 1 2 |
LF MF |
28.3 ± 6.7 vs. 38.2 ± 7.8 27.4 ± 8.5 vs. 38.2 ± 10.9 |
9.9 (35.0) 10.8 (40.9) |
0.001a 0.002b |
1.36 1.10 |
| Taaffe et al. [40] | 11 12 11 |
68.5 (± 3.6) 69.4 (± 3.0) 71.0 (± 4.1) |
24 weeks | LPull | 3 (8) | 1 2 3 |
LF MF HF |
36.0 ± 14.2 vs. 45.3 ± 4.31 35.8 ± 9.7 vs. 47.0 ± 4.20 33.6 ± 10.9 vs. 48.9 ± 4.31 |
9.3 (25.83) 11.2 (31.28) 15.3 (45.54) |
≤ 0.001a ≤ 0.001a ≤ 0.001a |
0.89 1.50 1.85 |
| Taaffe et al. [40] | 11 12 11 |
68.5 (± 3.6) 69.4 (± 3.0) 71.0 (± 4.1) |
24 weeks | BC | 3 (8) | 1 2 3 |
LF MF HF |
16.5 ± 7.1 vs. 21.9 ± 2.99 17.0 ± 4.3 vs. 24.4 ± 2.77 16.7 ± 6.2 vs. 23.2 ± 2.99 |
5.4 (32.73) 7.4 (43.53) 6.5 (38.92) |
≤ 0.001a ≤ 0.001a ≤ 0.001a |
0.99 2.05 1.34 |
| Taaffe et al. [40] | 11 12 11 |
68.5 (± 3.6) 69.4 (± 3.0) 71.0 (± 4.1) |
24 weeks | BExt | 3 (8) | 1 2 3 |
LF MF HF |
62.3 ± 24.5 vs. 83.1 ± 9.17 63.4 ± 11.3 vs. 84.2 ± 9.70 65.0 ± 26.5 vs. 84.4 ± 9.29 |
20.8 (33.39) 20.8 (32.81) 19.4 (29.85) |
≤ 0.001a ≤ 0.001a ≤ 0.001a |
1.12 1.98 0.98 |
| Taaffe et al. [40] | 11 12 11 |
68.5 (± 3.6) 69.4 (± 3.0) 71.0 (± 4.1) |
24 weeks | LP | 3 (8) | 1 2 3 |
LF MF HF |
109.5 ± 29.8 vs. 135.2 ± 12.27 113.3 ± 19.3 vs. 142.8 ± 12.47 110.5 ± 29.5 vs. 145.1 ± 3.7 |
25.7 (23.47) 29.5 (26.04) 34.6 (31.31) |
≤ 0.001a ≤ 0.001a ≤ 0.001a |
1.13 1.82 1.65 |
| Taaffe et al. [40] | 11 12 11 |
68.5 (± 3.6) 69.4 (± 3.0) 71.0 (± 4.1) |
24 weeks | KExt | 3 (8) | 1 2 3 |
LF MF HF |
39.3 ± 15.4 vs. 67.1 ± 10.95 43.2 ± 8.6 vs. 72.6 ± 10.74 42.4 ± 12.4 vs. 62.6 ± 10.61 |
27.8 (70.74) 29.4 (68.06) 20.2 (47.64) |
≤ 0.001a ≤ 0.001a ≤ 0.001a |
2.08 3.02 1.75 |
| Taaffe et al. [40] | 10 12 11 |
68.5 (± 3.6) 69.4 (± 3.0) 71.0 (± 4.1) |
24 weeks | KFlex | 3 (8) | 1 2 3 |
LF MF HF |
16.3 ± 7.5 vs. 28.4 ± 4.43 19.6 ± 6.8 vs. 30.4 ± 4.50 20.0 ± 9.4 vs. 28.5 ± 4.64 |
12.1 (74.23) 10.8 (55.10) 8.5 (42.50) |
≤ 0.001a ≤ 0.001a ≤ 0.001a |
1.96 1.87 1.15 |
| Farinatti et al. [41] | 10 11 10 |
72 (± 5.0) 66 (± 7.0) 68 (± 4.0) |
16 weeks | DumBP | 1 (8–12) | 1 2 3 |
LF MF HF |
8.2 ± 1.8 vs. 13.0 ± 2.0 9.6 ± 2.2 vs. 14.4 ± 5.2 10.4 ± 0.9 vs. 15.6 ± 1.7 |
4.8 (58.54) 4.8 (50.0) 5.2 (50.0) |
≤ 0.01a ≤ 0.01a ≤ 0.01a |
2.52 1.20 3.82 |
| Farinatti et al. [41] | 10 11 10 |
72 (± 5.0) 66 (± 7.0) 68 (± 4.0) |
16 weeks | DCur | 1 (8–12) | 1 2 3 |
LF MF HF |
7.8 ± 1.5 vs. 12.2 ± 2.3 8.4 ± 1.7 vs. 13.6 ± 2.6 9.2 ± 1.8 vs. 15.6 ± 0.9 |
4.4 (56.41) 5.2 (61.90) 6.4 (69.57) |
≤ 0.01a ≤ 0.01a ≤ 0.01a |
2.27 2.37 4.50 |
| Farinatti et al. [41] | 10 11 10 |
72 (± 5.0) 66 (± 7.0) 68 (± 4.0) |
16 weeks | KExt | 1 (8–12) | 1 2 3 |
LF MF HF |
18.0 ± 3.7 vs. 25.6 ± 3.2 19.2 ± 4.6 ± 29.6 ± 7.4 19.8 ± 4.9 vs. 32.0 ± 6.8 |
7.6 (42.22) 10.4 (54.17) 12.2 (61.62) |
≤ 0.01a ≤ 0.01a ≤ 0.01a |
2.20 1.69 2.06 |
| Farinatti et al. [42] | 10 11 10 |
72 (± 5.0) 66 (± 7.0) 68 (± 4.0) |
16 weeks | StCR | 1 (8–12) | 1 2 3 |
LF MF HF |
12.0 ± 2.0 vs. 16.8 ± 1.9 12.2 ± 3.0 vs. 17.0 ± 3.7 11.8 ± 0.5 vs. 16.8 ± 1.5 |
4.8 (40.0) 4.8 (39.34) 5.0 (42.37) |
≤ 0.01a ≤ 0.01a ≤ 0.01a |
2.46 1.43 4.47 |
| Burt et al. [42] | 10 11 |
Students | 8 weeks. | LP | 1 (6–10) | 1 2 |
LF MF |
263.31 ± 37.23 vs. 362.65 ± 51.06 244.89 ± 45.80 vs. 391.53 ± 45.18 |
99.34 (99.34) 146.64 (59.9) |
≤ 0.0001a ≤ 0.0001a |
2.22 3.22 |
| Serra et al. [67] | 18 17 10 |
41.4 (± 9.9) | 4 months 8 months |
BP | 3 (10–12) | 2 3 4 |
MF HF HF |
41.7 ± 16.4 vs. 57.4 ± 15.4 38.8 ± 16.3 vs. 59.5 ± 16.5 39.0 ± 16.1 vs. 62.8 ± 18.1 |
36.3 (37.6) 46.5 (53.4) 65.1 (61.0) |
0.01a 0.001a 0.01a |
0.99 1.26 1.39 |
| Serra et al. [67] | 18 17 10 |
41.4 (± 9.9) | 4 months 8 months |
LP | 3 (10–12) | 2 3 4 |
MF HF HF |
83.3 ± 21.4 vs. 113.3 ± 26.6 88.2 ± 21.9 vs. 112.5 ± 18.5 80.0 ± 25.4 vs. 117.8 ± 30.5 |
30.4 (36.01) 32.4 (27.6) 45.4 (47.3) |
0.001a ≤ 0.001a 0.01a |
1.24 1.20 1.35 |
| Serra et al. [67] | 18 17 10 |
41.4 (± 9.9) | 4 months 8 months |
LPull | 3 (10–12) | 2 3 4 |
MF HF HF |
50.1 ± 12.0 vs. 67.4 ± 12.0 52.2 ± 12.8 vs. 69.7 ± 17.0 54.5 ± 16.2 vs. 77.5 ± 18.1 |
29.4 (34.5) 32.0 (33.5) 46.0 (42.2) |
0.0001a 0.002a 0.01a |
1.44 1.16 1.34 |
| Benton et al. [36] | 11 10 |
47.6 (± 1.2) | 8 weeks | CP | 3–6 (8–12) | 3 4 |
HF HF |
37.4 ± 2.5 vs. 50.0 ± 3.5 44.5 ± 3.0 vs. 59.7 ± 4.1 |
12.6 (34.0) 15.2 (34.2) |
≤ 0.001a ≤ 0.001a |
1.25 1.34 |
| Benton et al. [36] | 11 10 |
47.6 (± 1.2) | 8 weeks | LP | 3–6 (8–12) | 3 4 |
HF HF |
105.1 ± 9.8 vs. 135.7 ± 16.7 119.7 ± 11.5 vs. 178.6 ± 19.6 |
30.6 (29.1) 58.9 (49.2) |
≤ 0.001a ≤ 0.001a |
0.67 1.16 |
| Ribeiro et al. [37] | 5 5 |
26.7 (± 2.7) | 4 weeks | BP | 4 (6–20) | 4 6 |
HF HF |
104.4 ± 19.3 vs. 113.2 ± 23.0 105.6 ± 16.4 vs. 117.6 ± 16.3 |
8.8 (8.4) 12 (11.4) |
0.53 0.28 |
0.41 0.73 |
| Hoffman et al. [38] | 12 15 23 11 |
19.7 ± (1.4) 20.1 ± (1.5) 20.1 ± (1.1) 19.7 ± (1.1) |
10 weeks. | BP | 1–5 (2–10) | 3 4 5 6 |
HF HF HF HF |
107.2 ± 11.6 vs. 109.1 ± 28.7 127.7 ± 13.9 vs. 132.2 ± 14.5 131.1 ± 20.1 vs. 135.3 ± 19.0 143.9 ± 12.0 vs. 149.7 ± 17.3 |
1.9 (1.8) 4.5 (3.5) 4.2 (3.2) 5.8 (4.0) |
0.83 0.39 0.47 0.37 |
0.09 0.32 0.21 0.39 |
| Hoffman et al. [38] | 12 15 23 11 |
19.7 ± (1.4) 20.1 ± (1.5) 20.1 ± (1.1) 19.7 ± (1.1) |
10 weeks. | Sq | 1–5 (2–10) | 3 4 5 6 |
HF HF HF HF |
140.1 ± 18.6 vs. 147.4 ± 38.9 173.6 ± 36.2 vs. 186.3 ± 31.9 170.6 ± 19.4 vs. 183.4 ± 22.1 191.6 ± 34.9 vs. 204.1 ± 39.5 |
7.3 (5.2) 12.7 (7.3) 12.8 (7.5) 12.5 (6.5) |
0.56 0.32 0.04a 0.44 |
0.24 0.37 0.62 0.34 |
| Padilha et al. [43] | 13 14 |
68.9 (± 5.0) 66.7 (± 13.9) |
12 weeks | CP | 1 (10–15) | 2 3 |
MF HF |
35.7 ± 6.6 vs. 42.2 ± 8.0 37.1 ± 3.8 vs. 47.3 ± 4.6 |
6.5 (18.2) 10.2 (27.5) |
≤ 0.05b ≤ 0.05b |
0.89 2.42 |
| Padilha et al. [43] | 13 14 |
68.9 (± 5.0) | 12 weeks | LE | 1 (10–15) | 2 3 |
MF HF |
41.3 ± 9.3 vs. 48.9 ± 9.1 46.1 ± 10.5 vs. 53.8 ± 12.5 |
7.6 (18.4) 7.7 (16.7) |
≤ 0.05b ≤ 0.05b |
0.83 0.67 |
| Padilha et al. [43] | 13 14 |
66.7 (± 13.9) | 12 weeks | BC | 1 (10–15) | 2 3 |
MF HF |
17.0 ± 3.3 vs. 23.4 ± 3.8 17.7 ± 2.5 vs. 24.2 ± 3.6 |
6.4 (37.6) 6.5 (26.9) |
≤ 0.05b ≤ 0.05b |
1.80 2.10 |
| Hunter [39] | 14 10 |
22.2 (± 2.2) c | 7 weeks | BP | 2–3 (7–10) | 3 4 |
HF HF |
69.1 ± 22.08 vs. 77.3 ± 20.58 59.3 ± 25.93 vs. 69.20 ± 25.61 |
8.2 (11.9) 9.9 (16.7) |
0.32 0.40 |
0.38 0.38 |
| Hunter [39] | 11 11 |
23.1 (± 0.9) d | 7 weeks | BP | 2–3 (7–10) | 3 4 |
HF HF |
26.1 ± 5.97 vs. 31.3 ± 6.30 27.3 ± 7.30 vs. 36.40 ± 7.96 |
5.2 (19.9) 9.1 (33.3) |
0.32 ≤ 0.05b |
0.85 1.19 |
Abbreviations: N number of subjects, SD standard deviation, reps repetitions; per week number of days trained per week, ES effect size, Sq squat, LF low frequency (1 day per week), MF medium frequency (2 days per week), HF high frequency (≥ 3 day per week), BP bench press, WGPullD wide grip pulldown, CP chest press, LP leg press, LumExt lumbar extension, CervExt cervical extension, LPull lateral pulldown, BC bicep curl, BExt back extension, LP leg press, KExt knee extension, KFlex knee flexion, DumBP dumbbell bench press, DCurl dumbbell curl, StCR standing calf raise
aSignificantly greater than prior to training (p ≤ 0.01)
bSignificantly greater than prior to training (p ≤ 0.05)
cMale-only subjects
dFemale-only subjects