Eccentric versus concentric loading for muscle growth
In a 2026 Sports Medicine systematic review and meta-analysis of 49 studies and 773 participants, the authors' estimated effects suggest that accentuated eccentric loading — loading the eccentric phase more heavily than the concentric phase — showed greater acute responses than constant-load resistance training in four outcomes: blood lactate concentration immediately post-intervention, growth hormone concentration immediately post-intervention, muscle electrical activity during the eccentric phase (SMD = 0.37; p = 0.01), and rating of perceived exertion immediately post-intervention (SMD = 1.72; p = 0.01). Chronic adaptations were similar between the two methods, including muscle cross-sectional area (SMD = - 0.06; p = 0.84) and maximal concentric (SMD = 0.12; p = 0.41), eccentric and isometric strength. The authors note that considerable variance exists in certain outcomes, and conclude that there is a lack of evidence for superior chronic benefits in strength or muscle architecture over constant-load resistance training. The abstract describes the population only as 773 participants across 49 studies, with no training status, sex or age reported.
Xing Zhang (2026) · Sports Medicine · PMID 41945297
This paper does NOT say eccentric training is useless, and it does NOT compare eccentric-only training against concentric-only training. It compares accentuated eccentric loading — a heavier load on the lowering phase within an otherwise normal set — against constant-load training. Both groups trained. It also does NOT say slow tempos, controlled lowering, or "time under tension" are useless: repetition tempo and duration were not the variable tested, so this cannot be used to support a tempo claim. The abstract states no participant training status, sex or age, and PubMed's MeSH list carries only "Humans", so it cannot be claimed as "in trained lifters" or for any sex or age group. The muscle fascicle length estimate (SMD = 0.90) is large but non-significant (p = 0.17) and the authors group it under "similar chronic adaptations" — reporting it as an eccentric advantage would be a misread. The abstract does not state how many of the 49 studies measured muscle cross-sectional area, and the authors write that "considerable variance exists in certain outcomes"; this is an absence of a detected difference, not proof of exact equivalence. Two scope limits from the Methods: the literature search ran only through July 3, 2024, so despite the 2026 publication date this is not current to 2026, and only English-language studies were eligible. Finally, the abstract never states that the pooled studies were randomised controlled trials, and PubMed tags no such publication type — so this must not be presented as a meta-analysis of RCTs.
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- Forty-ninestudies
Number of studies pooled in the systematic review and meta-analysis
Forty-nine studies involving 773 participants were included.
- 773participants
Total participants across all pooled studies
Forty-nine studies involving 773 participants were included.
- - 0.06standardized mean difference
Chronic difference in muscle cross-sectional area between accentuated eccentric loading and constant-load training — essentially zero, with the sign slightly favouring constant-load training. The authors file it under "similar chronic adaptations". Note that "- 0.06" also appears twice elsewhere in this sentence (immediate countermovement jump height, blood lactate during the intervention); it is bound to cross-sectional area by the trailing p = 0.84, which occurs exactly once in the abstract.
Although considerable variance exists in certain outcomes, our estimated effects suggest that, compared to constant-load RT, AEL results in (1) similar acute responses in loads lifted during the concentric phase (standardized mean difference [SMD] = - 0.16; p = 0.48), mechanical performance at submaximal loads during the concentric phase (SMD = - 0.07; p = 0.37), countermovement jump height both immediately (SMD = - 0.06; p = 0.86) and delayed (SMD = - 0.23; p = 0.44) post-intervention, maximal voluntary isometric force immediately post-intervention (SMD = 0.03; p = 0.89), blood lactate concentration during the intervention (SMD = - 0.06; p = 0.78), testosterone concentration immediately post-intervention (SMD = 0.68; p = 0.15), creatine kinase concentration both immediately (SMD = 0.09; p = 0.72) and delayed (SMD = 0.14; p = 0.48) post-intervention, cortisol concentration immediately post-intervention (SMD = 0.39; p = 0.05), heart rate during the intervention (SMD = 1.18; p = 0.07), acute muscle swelling immediately post-intervention (SMD = 0.26; p = 0.42), muscle electrical activity during the concentric phase (SMD = - 0.01; p = 0.90), and muscle soreness both immediately (SMD = 0.28; p = 0.30) and delayed (SMD = 0.18; p = 0.28) post-intervention; (2) greater acute responses in blood lactate concentration immediately post-intervention (SMD = 0.44; p = 0.03), growth hormone concentration immediately post-intervention (SMD = 0.50; p = 0.01), muscle electrical activity during the eccentric phase (SMD = 0.37; p = 0.01), and rating of perceived exertion immediately post-intervention (SMD = 1.72; p = 0.01); (3) similar chronic adaptations in maximal concentric strength (SMD = 0.12; p = 0.41), maximal eccentric strength (SMD = 0.19; p = 0.58), maximal isometric strength (SMD = 0.03; p = 0.93), countermovement jump height (SMD = 0.04; p = 0.87), muscle fascicle angle (SMD = - 0.10; p = 0.77), muscle fascicle length (SMD = 0.90; p = 0.17), and muscle cross-sectional area (SMD = - 0.06; p = 0.84).
- 0.84p-value
p-value for the muscle cross-sectional area comparison — nowhere near significance. Occurs exactly once in the abstract.
Although considerable variance exists in certain outcomes, our estimated effects suggest that, compared to constant-load RT, AEL results in (1) similar acute responses in loads lifted during the concentric phase (standardized mean difference [SMD] = - 0.16; p = 0.48), mechanical performance at submaximal loads during the concentric phase (SMD = - 0.07; p = 0.37), countermovement jump height both immediately (SMD = - 0.06; p = 0.86) and delayed (SMD = - 0.23; p = 0.44) post-intervention, maximal voluntary isometric force immediately post-intervention (SMD = 0.03; p = 0.89), blood lactate concentration during the intervention (SMD = - 0.06; p = 0.78), testosterone concentration immediately post-intervention (SMD = 0.68; p = 0.15), creatine kinase concentration both immediately (SMD = 0.09; p = 0.72) and delayed (SMD = 0.14; p = 0.48) post-intervention, cortisol concentration immediately post-intervention (SMD = 0.39; p = 0.05), heart rate during the intervention (SMD = 1.18; p = 0.07), acute muscle swelling immediately post-intervention (SMD = 0.26; p = 0.42), muscle electrical activity during the concentric phase (SMD = - 0.01; p = 0.90), and muscle soreness both immediately (SMD = 0.28; p = 0.30) and delayed (SMD = 0.18; p = 0.28) post-intervention; (2) greater acute responses in blood lactate concentration immediately post-intervention (SMD = 0.44; p = 0.03), growth hormone concentration immediately post-intervention (SMD = 0.50; p = 0.01), muscle electrical activity during the eccentric phase (SMD = 0.37; p = 0.01), and rating of perceived exertion immediately post-intervention (SMD = 1.72; p = 0.01); (3) similar chronic adaptations in maximal concentric strength (SMD = 0.12; p = 0.41), maximal eccentric strength (SMD = 0.19; p = 0.58), maximal isometric strength (SMD = 0.03; p = 0.93), countermovement jump height (SMD = 0.04; p = 0.87), muscle fascicle angle (SMD = - 0.10; p = 0.77), muscle fascicle length (SMD = 0.90; p = 0.17), and muscle cross-sectional area (SMD = - 0.06; p = 0.84).
- 0.37standardized mean difference
ACUTE response. Muscle electrical activity during the eccentric phase was genuinely higher with accentuated eccentric loading (p = 0.01), sitting in the authors' clause (2) "greater acute responses". The stimulus really was different; it just did not translate into more muscle. Distinct from concentric-phase electrical activity in clause (1), which was SMD = - 0.01 (p = 0.90).
Although considerable variance exists in certain outcomes, our estimated effects suggest that, compared to constant-load RT, AEL results in (1) similar acute responses in loads lifted during the concentric phase (standardized mean difference [SMD] = - 0.16; p = 0.48), mechanical performance at submaximal loads during the concentric phase (SMD = - 0.07; p = 0.37), countermovement jump height both immediately (SMD = - 0.06; p = 0.86) and delayed (SMD = - 0.23; p = 0.44) post-intervention, maximal voluntary isometric force immediately post-intervention (SMD = 0.03; p = 0.89), blood lactate concentration during the intervention (SMD = - 0.06; p = 0.78), testosterone concentration immediately post-intervention (SMD = 0.68; p = 0.15), creatine kinase concentration both immediately (SMD = 0.09; p = 0.72) and delayed (SMD = 0.14; p = 0.48) post-intervention, cortisol concentration immediately post-intervention (SMD = 0.39; p = 0.05), heart rate during the intervention (SMD = 1.18; p = 0.07), acute muscle swelling immediately post-intervention (SMD = 0.26; p = 0.42), muscle electrical activity during the concentric phase (SMD = - 0.01; p = 0.90), and muscle soreness both immediately (SMD = 0.28; p = 0.30) and delayed (SMD = 0.18; p = 0.28) post-intervention; (2) greater acute responses in blood lactate concentration immediately post-intervention (SMD = 0.44; p = 0.03), growth hormone concentration immediately post-intervention (SMD = 0.50; p = 0.01), muscle electrical activity during the eccentric phase (SMD = 0.37; p = 0.01), and rating of perceived exertion immediately post-intervention (SMD = 1.72; p = 0.01); (3) similar chronic adaptations in maximal concentric strength (SMD = 0.12; p = 0.41), maximal eccentric strength (SMD = 0.19; p = 0.58), maximal isometric strength (SMD = 0.03; p = 0.93), countermovement jump height (SMD = 0.04; p = 0.87), muscle fascicle angle (SMD = - 0.10; p = 0.77), muscle fascicle length (SMD = 0.90; p = 0.17), and muscle cross-sectional area (SMD = - 0.06; p = 0.84).
- 1.72standardized mean difference
ACUTE response. Rating of perceived exertion immediately post-intervention was much higher with accentuated eccentric loading (p = 0.01) — it felt substantially harder. The largest effect in the abstract.
Although considerable variance exists in certain outcomes, our estimated effects suggest that, compared to constant-load RT, AEL results in (1) similar acute responses in loads lifted during the concentric phase (standardized mean difference [SMD] = - 0.16; p = 0.48), mechanical performance at submaximal loads during the concentric phase (SMD = - 0.07; p = 0.37), countermovement jump height both immediately (SMD = - 0.06; p = 0.86) and delayed (SMD = - 0.23; p = 0.44) post-intervention, maximal voluntary isometric force immediately post-intervention (SMD = 0.03; p = 0.89), blood lactate concentration during the intervention (SMD = - 0.06; p = 0.78), testosterone concentration immediately post-intervention (SMD = 0.68; p = 0.15), creatine kinase concentration both immediately (SMD = 0.09; p = 0.72) and delayed (SMD = 0.14; p = 0.48) post-intervention, cortisol concentration immediately post-intervention (SMD = 0.39; p = 0.05), heart rate during the intervention (SMD = 1.18; p = 0.07), acute muscle swelling immediately post-intervention (SMD = 0.26; p = 0.42), muscle electrical activity during the concentric phase (SMD = - 0.01; p = 0.90), and muscle soreness both immediately (SMD = 0.28; p = 0.30) and delayed (SMD = 0.18; p = 0.28) post-intervention; (2) greater acute responses in blood lactate concentration immediately post-intervention (SMD = 0.44; p = 0.03), growth hormone concentration immediately post-intervention (SMD = 0.50; p = 0.01), muscle electrical activity during the eccentric phase (SMD = 0.37; p = 0.01), and rating of perceived exertion immediately post-intervention (SMD = 1.72; p = 0.01); (3) similar chronic adaptations in maximal concentric strength (SMD = 0.12; p = 0.41), maximal eccentric strength (SMD = 0.19; p = 0.58), maximal isometric strength (SMD = 0.03; p = 0.93), countermovement jump height (SMD = 0.04; p = 0.87), muscle fascicle angle (SMD = - 0.10; p = 0.77), muscle fascicle length (SMD = 0.90; p = 0.17), and muscle cross-sectional area (SMD = - 0.06; p = 0.84).
- 0.12standardized mean difference
CHRONIC adaptation. Difference in maximal concentric strength between the two methods (p = 0.41) — no meaningful advantage. Sits in the authors' clause (3) "similar chronic adaptations".
Although considerable variance exists in certain outcomes, our estimated effects suggest that, compared to constant-load RT, AEL results in (1) similar acute responses in loads lifted during the concentric phase (standardized mean difference [SMD] = - 0.16; p = 0.48), mechanical performance at submaximal loads during the concentric phase (SMD = - 0.07; p = 0.37), countermovement jump height both immediately (SMD = - 0.06; p = 0.86) and delayed (SMD = - 0.23; p = 0.44) post-intervention, maximal voluntary isometric force immediately post-intervention (SMD = 0.03; p = 0.89), blood lactate concentration during the intervention (SMD = - 0.06; p = 0.78), testosterone concentration immediately post-intervention (SMD = 0.68; p = 0.15), creatine kinase concentration both immediately (SMD = 0.09; p = 0.72) and delayed (SMD = 0.14; p = 0.48) post-intervention, cortisol concentration immediately post-intervention (SMD = 0.39; p = 0.05), heart rate during the intervention (SMD = 1.18; p = 0.07), acute muscle swelling immediately post-intervention (SMD = 0.26; p = 0.42), muscle electrical activity during the concentric phase (SMD = - 0.01; p = 0.90), and muscle soreness both immediately (SMD = 0.28; p = 0.30) and delayed (SMD = 0.18; p = 0.28) post-intervention; (2) greater acute responses in blood lactate concentration immediately post-intervention (SMD = 0.44; p = 0.03), growth hormone concentration immediately post-intervention (SMD = 0.50; p = 0.01), muscle electrical activity during the eccentric phase (SMD = 0.37; p = 0.01), and rating of perceived exertion immediately post-intervention (SMD = 1.72; p = 0.01); (3) similar chronic adaptations in maximal concentric strength (SMD = 0.12; p = 0.41), maximal eccentric strength (SMD = 0.19; p = 0.58), maximal isometric strength (SMD = 0.03; p = 0.93), countermovement jump height (SMD = 0.04; p = 0.87), muscle fascicle angle (SMD = - 0.10; p = 0.77), muscle fascicle length (SMD = 0.90; p = 0.17), and muscle cross-sectional area (SMD = - 0.06; p = 0.84).
- 0.90standardized mean difference
CHRONIC adaptation. The one large point estimate favouring accentuated eccentric loading, but NOT statistically significant (p = 0.17), and the authors place it inside clause (3), "similar chronic adaptations". HARD EDITORIAL CONSTRAINT: do not publish this number alone or as a win. It is the single most misusable value in this abstract, and it is retained here only so an editor can recognise and refuse it.
Although considerable variance exists in certain outcomes, our estimated effects suggest that, compared to constant-load RT, AEL results in (1) similar acute responses in loads lifted during the concentric phase (standardized mean difference [SMD] = - 0.16; p = 0.48), mechanical performance at submaximal loads during the concentric phase (SMD = - 0.07; p = 0.37), countermovement jump height both immediately (SMD = - 0.06; p = 0.86) and delayed (SMD = - 0.23; p = 0.44) post-intervention, maximal voluntary isometric force immediately post-intervention (SMD = 0.03; p = 0.89), blood lactate concentration during the intervention (SMD = - 0.06; p = 0.78), testosterone concentration immediately post-intervention (SMD = 0.68; p = 0.15), creatine kinase concentration both immediately (SMD = 0.09; p = 0.72) and delayed (SMD = 0.14; p = 0.48) post-intervention, cortisol concentration immediately post-intervention (SMD = 0.39; p = 0.05), heart rate during the intervention (SMD = 1.18; p = 0.07), acute muscle swelling immediately post-intervention (SMD = 0.26; p = 0.42), muscle electrical activity during the concentric phase (SMD = - 0.01; p = 0.90), and muscle soreness both immediately (SMD = 0.28; p = 0.30) and delayed (SMD = 0.18; p = 0.28) post-intervention; (2) greater acute responses in blood lactate concentration immediately post-intervention (SMD = 0.44; p = 0.03), growth hormone concentration immediately post-intervention (SMD = 0.50; p = 0.01), muscle electrical activity during the eccentric phase (SMD = 0.37; p = 0.01), and rating of perceived exertion immediately post-intervention (SMD = 1.72; p = 0.01); (3) similar chronic adaptations in maximal concentric strength (SMD = 0.12; p = 0.41), maximal eccentric strength (SMD = 0.19; p = 0.58), maximal isometric strength (SMD = 0.03; p = 0.93), countermovement jump height (SMD = 0.04; p = 0.87), muscle fascicle angle (SMD = - 0.10; p = 0.77), muscle fascicle length (SMD = 0.90; p = 0.17), and muscle cross-sectional area (SMD = - 0.06; p = 0.84).
Not specified in the abstract beyond "Forty-nine studies involving 773 participants were included." The abstract gives no training status, sex, or age, and the PubMed MeSH list carries only "Humans" with no Adult, Male, Female or Young Adult descriptors. This claim therefore cannot be attributed to trained lifters, or to any sex or age group. Any card must describe the population as "773 participants across 49 studies" and nothing more.
Xing Zhang, et al. (2026)Acute and Chronic Effects of Accentuated Eccentric Loading vs. Constant-Load Resistance Training: A Systematic Review and Meta-analysis
Sports Medicine · PMID 41945297
Meta-analysis · Forty-nine studies · 773 participants
Who funded itSee the paper's funding and conflict-of-interest statement.
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