Lower-body muscular strength (pooled composite)

Method

Meta-analytic aggregate of lower-limb strength across whichever tests the primary trials used — back squat, leg press, knee extension, isokinetic knee torque — reported as a standardised mean difference, or in kilograms where the review pooled a common test. The constituent tests are listed on the edge.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

Confused with squat one-repetition maximum, a single lift on the existing 1RM strength node; a region-level aggregate is not a lift, and pooling the two counts a composite as evidence for its own component. SIGN TRAP SPECIFIC TO THIS NODE: at least one review reports a BENEFICIAL lower-limb strength effect as a NEGATIVE standardised mean difference (-0.38), because the constituent tests entered the model on a deficit or time scale. The source's own numeric sign therefore cannot be trusted; every edge must be checked against the review's stated direction of effect before it is written. Also distinct from isometric peak force, a fixed-angle maximal contraction, and from the upper-body composite.

Findings

3 findings from 2 compounds, strongest first.

• creatine — increases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “In comparison with a placebo, creatine supplementation combined with resistance training significantly increased upper-body (WMD = 4.43 kg, p < 0.001) and lower-body strength (WMD = 11.35 kg, p < 0.001).”

  Study

  meta-analysis

  Population

  adults <50 years of age undertaking resistance training

  Effects of Creatine Supplementation and Resistance Training on Muscle Strength Gains in Adults <50 Years of Age: A Systematic Review and Meta-Analysis.2024PMID:39519498An author is affiliated with a producer

• caffeine — no detected effect on

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.FindingNull resultreplicated ×1

  “A subgroup analysis indicated that caffeine significantly improves upper (SMD = 0.21; 95% CI: 0.02, 0.39; p = 0.026; Fig. 3) but not lower body strength (SMD = 0.15; 95% CI: -0.05, 0.34; p = 0.147; Fig. 4).”

  Study

  meta-analysis

  Dose

  Acute pre-exercise ingestion (capsule, liquid or gel), mean 4.8 mg/kg, range 0.9-6 mg/kg, 45-60 min before testing

  Population

  Healthy adolescent and young-adult participants, trained and untrained, of both sexes; LOWER-BODY SUBGROUP of the pooled 1RM maximal-strength analysis, not the overall estimate. Constituent tests: back squat, leg press.

  Effect 0.15 standardised mean difference, 95% CI -0.05 to 0.34

  Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis.2018PMID:29527137

• caffeine — no detected effect on

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.FindingNull resultreplicated ×1

  “In a subgroup analysis that considered only lower-body 1RM tests, there was no significant difference between caffeine and placebo (SMD: 0.16; 95% CI: −0.03, 0.35; p = 0.109; I2 = 0%).”

  Study

  meta-analysis

  Population

  Healthy adult women; subgroup analysis restricted to lower-body 1RM tests (squat, leg press, knee extension), not the overall estimate

  Effect 0.16 standardised mean difference, 95% CI -0.03 to 0.35

  Ergogenic Effects of Acute Caffeine Intake on Muscular Endurance and Muscular Strength in Women: A Meta-Analysis.2021PMID:34072182