⚠️ Auto-extracted by Claude on 2026-08-10 — not yet verified against the full PDF (DOI 10.3945/ajcn.111.021915). Paper is closed access with no PMC copy; full text was not obtainable. Numerics are drawn from the published abstract only. gap/no-fulltext-access
Fish-oil supplementation enhances the effects of strength training in elderly women
TL;DR
Randomized 45 elderly women (64 ± 1.4 y) to 90 days of strength training alone (ST), strength training + 2 g/d fish oil for 90 days (ST90), or strength training + 2 g/d fish oil starting 60 days before training and continuing through it (ST150, ~150 d total supplementation). All three groups gained peak torque and rate of torque development across all four muscle groups tested — strength training worked in every arm. But the gains were larger in the two fish-oil arms, and only the fish-oil arms showed pre→post changes in muscle activation level and electromechanical delay, plus better chair-rising performance. This is the foundational trial behind claims that omega-3 fatty acids potentiate resistance-training adaptation via a neuromuscular (not purely muscle-fiber) mechanism — but the trial has no placebo arm, is small, and cannot itself localize the effect to nerve vs. muscle.
Design
- Subjects: 45 community-dwelling elderly women, mean age 64 ± 1.4 y; no reported between-group differences at baseline.
- Arms (n≈15/group, per abstract):
- ST — strength training only, 90 days
- ST90 — strength training + 2 g/d fish oil, both starting simultaneously, 90 days
- ST150 — fish oil supplementation started 60 days before strength training began, then continued through the 90-day training period (~150 d total fish-oil exposure)
- Training: progressive strength training program (duration/frequency/load progression not captured from the abstract — verify against full text)
- Fish-oil dose: 2 g/d (fatty-acid composition/brand not captured from the abstract — verify against full text)
- Outcomes: peak torque and rate of torque development (knee flexors/extensors, plantar flexors/dorsiflexors) via isokinetic dynamometry; surface EMG-derived muscle activation level; electromechanical delay; functional chair-rising test.
Design limitation — no placebo control
There was no placebo capsule. The ST arm received strength training with no supplement of any kind (not even a matching inert capsule), so every fish-oil-vs-ST comparison in this trial is open-label supplement vs. no supplement, not a blinded placebo-controlled comparison. Expectancy effects, differential attention/contact time, and adherence-monitoring differences between the supplemented and unsupplemented arms are not controlled for. This is a first-order limitation for interpreting the magnitude of the reported group differences and should be stated whenever this trial is cited as evidence for an omega-3-specific effect1.
Key results
- Peak torque and rate of torque development increased pre→post in all three groups, across all four muscle groups tested — i.e., strength training produced the expected adaptation regardless of supplementation1.
- The magnitude of increase was greater in ST90 and ST150 than in ST alone1.
- Muscle activation level and electromechanical delay changed pre→post only in the fish-oil groups (ST90, ST150) — not in ST alone1.
- Chair-rising performance was better in the fish-oil groups than in ST alone1.
Proposed mechanism — neuromuscular, not just muscular
Because activation level (an EMG readout of the speed and extent of motor-unit recruitment) and electromechanical delay changed only in the supplemented arms while peak-torque gains occurred in all arms, this study is widely cited as evidence that omega-3 fatty acids act at the motor unit / neuromuscular junction level, augmenting neural drive and excitation-contraction coupling on top of the muscle-fiber hypertrophy/strength adaptation that strength training alone already produces. Note that electromechanical delay — the time lag between the onset of muscle electrical activation and the onset of measurable force — is not itself a pure readout of motor-unit recruitment: it also reflects excitation-contraction coupling (the calcium-release and cross-bridge-formation steps linking electrical activation to force generation) and series-elastic/tendon mechanics (how much slack and compliance in the tendon and connective tissue must be taken up before force is transmitted). A change in electromechanical delay is therefore consistent with a neuromuscular-junction/motor-unit mechanism but could equally reflect a change in excitation-contraction coupling or tendon stiffness/compliance.
This is an overstatement of what the data can show. The trial demonstrates greater electrical-activation and torque changes in the supplemented groups — it does not localize the effect to nerve vs. muscle, and cannot distinguish a neuromuscular-junction mechanism from, e.g., an anti-inflammatory effect on muscle membrane excitability, altered muscle fiber-type recruitment order, or an unblinded-adherence/expectancy confound (see design limitation above). Treat “omega-3 acts on the motor unit” as a hypothesis the data are consistent with, not a mechanism the study establishes. gap/no-mechanism
Extrapolation / generalizability
| Dimension | Status | Notes |
|---|---|---|
| Pathway conserved in humans? | not-applicable | Human RCT — no cross-species extrapolation needed |
| Phenotype conserved in humans? | not-applicable | Human RCT |
| Replicated in humans? | partial / contradicted-in-part | See § Later evidence below — pooled data support lower-body strength but not lean mass, walking performance, or upper-body strength; a 2023 subgroup analysis found co-supplementation alongside resistance training did not influence responses |
Limitations
- No placebo control — open-label supplement vs. no-supplement design; see § Design above.
- Small sample — n≈15 per arm.
- Single sex, narrow age band — women only, mean age ~64. Do not generalize to men or to older/frailer cohorts (e.g., 80+, sarcopenic, institutionalized).
- Mechanism not established — EMG/electromechanical findings are consistent with, but do not prove, a neuromuscular-junction-level mechanism (see § Proposed mechanism).
- Fish-oil formulation and exact training protocol not captured from the abstract — dose (2 g/d) is known; EPA:DHA ratio, brand, and detailed training program parameters require full-text verification. gap/no-fulltext-access
- Paper is closed access with no PMC deposit; this page is built from the published abstract only and has not been verified against the full PDF. gap/no-fulltext-access
Later evidence — mixed replication at the pooled level
Subsequent pooled/meta-analytic evidence in older adults is mixed and generally weaker than this single trial’s headline result:
- Cornish et al. 2022 (Nutrients 14(11):2221, doi:10.3390/nu14112221, PMID 35684018) — meta-analysis in older adults found omega-3 supplementation benefited lower-body strength (SMD 0.54, 95% CI 0.33–0.75), timed-up-and-go, and 30-second sit-to-stand performance, but found no effect on lean tissue mass, walking performance, or upper-body strength2.
- Santo André et al. 2023 (Advances in Nutrition 14(1):115–127, doi:10.1016/j.advnut.2022.11.005, PMID 36811583) — subgroup analysis found that omega-3 co-supplementation alongside resistance training did not influence training responses, in contrast to the Rodacki 2012 finding3. See santo-andre-2023-n3pufa-muscle-meta-analysis.
gap/needs-replication — the Rodacki 2012 neuromuscular-activation finding in particular has not been independently replicated with a placebo-controlled design.
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Footnotes
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rodacki-2012-fish-oil-strength-training-elderly-women · n=45 (≈15/arm) · randomized · model: elderly women (mean age 64y), no placebo arm ↩ ↩2 ↩3 ↩4 ↩5
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doi:10.3390/nu14112221 · meta-analysis · model: older adults (pooled RCTs) · open access ↩
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santo-andre-2023-n3pufa-muscle-meta-analysis · systematic-review · model: pooled RCTs, resistance-training subgroup ↩