Table 4. Summary of evidence for the effects of LL-BFRT compared with LL-, HL-RT, or no exercise in muscle strength.
| Outcome—Strength | Comparisons | Relative effect (95%CI) | BFRT / comparator (n studies) | Quality of evidence (GRADE) | Evidence and significance | |
|---|---|---|---|---|---|---|
| Average estimate in BFRT group | Average estimate in comparator group | |||||
| Bench press– 1RM | LL-BFRT: | LL-RT: | SMD 0.87 | 21/21 | ⊕◯◯◯ | Very low certainty evidence of a significant difference in bench press strength (1RM in Kgs) in favor of LL-BFRT compared to LL-RT at 2–4 weeks follow-up |
| Follow-up 2–4 weeks | Pooled weighted mean±SD was 119.8±15.4 (mean range 62.0 to 137.9) | Pooled weighted mean±SD was 105.0±16.4 (mean range 57.5 to 119.8) | [0.23, 1.51] | (2) | Very low 1 , 3 , 4 | |
| Statistically significant difference | ||||||
| Flexion—MVIC | LL-BFRT: | LL-RT: | SMD 1.64 | 30/26 | ⊕◯◯◯ | Very low certainty evidence of a significant difference in shoulder flexion strength (MVIC) in favor of the LL-BFRT group at the 6–8 weeks follow-up |
| Follow-up 6–8 weeks | Pooled weighted mean±SD was 14.15±1.16 (mean range 12.8 to 15.7) | Pooled weighted mean±SD was 10.0±0.64 (mean range 6.97 to 11.9) | [0.57, 2.71] | (2) | Very low 1 , 3 , 4 | |
| Statistically significant difference | ||||||
| External rotation in prone 90o –MVIC | LL-BFRT: | LL-RT: | MD 1.40 | 16/16 | ⊕◯◯◯ | Very low certainty evidence of a significant difference in external rotation in prone at 90° of abduction strength in favor of the LL-BFRT at the 8-week follow-up |
| Follow-up 8 weeks | Mean±SD was 16.1±0.7 | Mean±SD was 14.7±0.7 | [0.91, 1.89] Statistically significant difference | (1) | Very low 1 | |
| External rotation in prone 90o –MVIC | LL-BFRT: | LL-RT: | MD 0.19 | 24/22 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in external rotation in prone at 90° of abduction strength between the comparators at the 8-week follow-up |
| Follow-up 8 weeks | Mean±SD was 13.54±4.94 | Mean±SD was 13.35±5.7 | [-2.91, 3.29] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
| External rotation seated—Peak torque Nm | LL-BFRT: | LL-RT: | MD 5.30 | 14/10 | ⊕⊕◯◯ | Low certainty evidence of no significant difference in shoulder external rotation (in seated position) peak torque (isokinetic dynamometry) between LL-BFRT and LL-RT at the 6-week follow-up |
| [-0.18, 10.78] | ||||||
| Follow-up 6 weeks | Mean±SD was 20.4±6.7 | Mean±SD was 15.1±6.8 | Non statistically significant difference | (1) | Low | |
| External rotation seated—MVIC | LL-BFRT: | LL-RT: | MD 0.20 | 16/16 | ⊕◯◯◯ | Low certainty evidence of no significant difference in shoulder external rotation MVIC (in seated position) between LL-BFRT and LL-RT at the 8-week follow-up |
| Follow-up 8 weeks | Mean±SD was 20.4±6.7 | Mean±SD was 15.1±6.8 | [-0.08, 0.48] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
| Internal rotation seated—MVIC | LL-BFRT: | LL-RT: | MD 2.90 | 16/16 | ⊕◯◯◯ | Very low certainty evidence of a significant difference in (seated) internal rotation at 0° of abduction strength in favor of the LL-BFRT at the 8-week follow-up |
| Follow-up 8 weeks | Mean±SD was 23.1±0.7 | Mean±SD was 13.9±0.4 | [2.41, 3.39] | (1) | Very low 1 | |
| Statistically significant difference | ||||||
| Internal rotation in prone 90o –MVIC | LL-BFRT: | LL-RT: | MD 0.50 | 16/16 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in prone internal rotation at 90° of abduction strength between LL-BFRT and LL-RT at the 8-week follow-up |
| Follow-up 8 weeks | Mean±SD was 18.6±0.8 | Mean±SD was 18.1±0.8 | [-0.05, 1.05] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
| Abduction—MVIC | LL-BFRT: | LL-RT: | MD 3.85 | 14/10 | ⊕⊕◯◯ | Low certainty evidence of a significant difference in shoulder abduction strength in favor of the LL-BFRT group at the 6-week follow-up |
| Follow-up 6 weeks | Mean±SD was 8.6±4.1 | Mean±SD was 4.7±3.1 | [0.95, 6.75] | (1) | Low | |
| Statistically significant difference | ||||||
| Abduction—MVIC | LL-BFRT: | LL-RT: | MD -0.41 | 24/22 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in shoulder abduction strength between LL-BFRT and LL-RT at the 8-week follow-up |
| [-2.61, 1.79] | ||||||
| Follow-up 8 weeks | Mean±SD was 18.9±3.5 | Mean±SD was 19.3±4.1 | Non statistically significant difference | (1) | Very low 1 | |
| Scaption—MVIC | LL-BFRT: | LL-RT: | MD 4.77 | 14/10 | ⊕⊕◯◯ | Low certainty evidence of a significant difference in shoulder scaption strength in favor of the LL-BFRT group at the 6-week follow-up |
| Follow-up 6 weeks | Mean±SD was 38.9±18.2 | Mean±SD was 22.3±13.7 | [1.64, 7.90] | (1) | Low | |
| Statistically significant difference | ||||||
| Scaption—MVIC | LL-BFRT: | LL-RT: | MD -0.10 | 16/16 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in shoulder scaption strength between LL-BFRT and LL-RT at the 8-week follow-up |
| Follow-up 8 weeks | Mean±SD was 12.4±0.2 | Mean±SD was 12.5±0.2 | [-0.24, 0.04] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
| Strength | LL-BFRT: | HL-RT: | SMD -0.17 | 20/22 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in bench press 1RM strength between LL-BFRT and HL-RT at the 4–8 weeks follow-up |
| (Bench press—1RM) | Pooled weighted mean±SD was 56.4±9.7 (mean range 53.7 to 105.2) | Pooled weighted mean±SD was 55.3±10.0 (mean range 56.78 to 102.8) | [-0.78, 0.44] | (3) | Very low 1 , 3 , 4 | |
| Non statistically significant difference | ||||||
| Follow-up 4–8 weeks | ||||||
| Strength | LL-BFRT: | HL-RT: | MD -0.31 | 6/8 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in seated row strength between LL-BFRT and HL-RT at the 8-week follow-up |
| (Seated row– 1RM) | Mean±SD was 39.8±3.2 | Mean±SD was 40.1±5.1 | [-4.68, 4.06] | (1) | Very low 1 | |
| Follow-up 8 weeks | Non statistically significant difference | |||||
| Strength | LL-BFRT: | HL-RT: | MD 1.69 | 6/8 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in shoulder press strength between LL-BFRT and HL-RT at the 8-week follow-up |
| (Shoulder press –1RM) | Mean±SD was 21.3±5.1 | Mean±SD was 19.6±4.8 | [-3.56, 6.94] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
| Follow-up 8 weeks | ||||||
| Pectoralis major—MVIC | LL-BFRT: | HL-RT: | MD -14.32 | 6/5 | ⊕◯◯◯ | Very low certainty evidence of a significant difference in pectoralis major in favor of HL-RT at the 4-week follow-up |
| Follow-up 4 weeks | Mean±SD was 49.6±8.1 | Mean±SD was 63.9±7.1 | [-23.35, -5.29] | (1) | Very low 1 | |
| Statistically significant difference | ||||||
| Lower trapezius—MVIC | LL-BFRT: | HL-RT: | MD -4.92 | 6/5 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in lower trapezius strength between LL-BFRT and HL-RT at the 4-week follow-up |
| Follow-up 4 weeks | Mean±SD was 32.6±5.5 | Mean±SD was 37.5±4.6 | [-10.90, 1.06] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
| External rotation in prone 90o –MVIC | LL-BFRT: | HL-RT: | MD -2.72 | 6/5 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in external rotation in prone and 90° of shoulder abduction strength between LL-BFRT and HL-RT at the 4-week follow-up |
| Follow-up 4 weeks | Mean±SD was 39.6±15.8 | Mean±SD was 42.3±9.2 | [-17.71, 12.27] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
| Prone row—MVIC | LL-BFRT: | HL-RT: | MD -0.83 | 6/5 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in prone row strength between LL-BFRT and HL-RT at the 4-week follow-up |
| Mean±SD was | Mean±SD was | [-21.60, 19.94] | ||||
| Follow-up 4 weeks | 104.2±18.6 | 105.0±16.6 | Non statistically significant difference | (1) | Very low 1 | |
| Scapular retraction—MVIC | LL-BFRT: | HL-RT: | MD 0.50 | 6/5 | ⊕◯◯◯ | Very low certainty evidence of no significant difference in scapular retraction strength between LL-BFRT and HL-RT at the 4-week follow-up |
| Follow-up 4 weeks | Mean±SD was 247.5±34.2 | Mean±SD was 247.0±25.9 | [-35.03, 36.03] | (1) | Very low 1 | |
| Non statistically significant difference | ||||||
1 Downgraded due to Risk of Bias.
2 Downgraded due to inconsistency.
3 Downgraded due to indirectness.
4 Downgraded due to imprecision.
Abbreviations: GRADE, Grading of Recommendations Assessment, Development and Evaluation; LL, low load; LL-BFRT, low load blood flow restriction training; HL, high load; MD, mean difference; MVIC, maximum voluntary isometric contraction; 1RM, one repletion maximum; RT, resistance training; SD, standard deviation; SMD, standardised mean difference.