Evidence map›Paper›PMID 41649381›Full record

ArticleMuscle & nerve2026

Post Activation Potentiation Is Greater in Human Triceps Brachii Versus Triceps Surae Muscles.

William S Zoughaib, Madison J Fry, Ahaan Singhal, Richard L Hoffman, Andrew R Coggan

Abstract readComparative Study
In one paragraph

Article in Muscle & nerve, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

William S ZoughaibExercise Physiology Laboratory, Department of Kinesiology, School of Health & Human Sciences, Indiana University Indianapolis, Indianapolis, Indiana, USA.
Madison J FryExercise Physiology Laboratory, Department of Kinesiology, School of Health & Human Sciences, Indiana University Indianapolis, Indianapolis, Indiana, USA.
Ahaan SinghalExercise Physiology Laboratory, Department of Kinesiology, School of Health & Human Sciences, Indiana University Indianapolis, Indianapolis, Indiana, USA.
Richard L HoffmanExercise Physiology Laboratory, Department of Kinesiology, School of Health & Human Sciences, Indiana University Indianapolis, Indianapolis, Indiana, USA.
Andrew R CogganExercise Physiology Laboratory, Department of Kinesiology, School of Health & Human Sciences, Indiana University Indianapolis, Indianapolis, Indiana, USA.ORCID https://orcid.org/0000-0002-7723-8872

Funding

The Inorganic Nitrate and eXercise performance in Heart Failure (iNIX-HF): - a phase II clinical trialR33HL155858 · NHLBI · WASHINGTON UNIVERSITY · PI ANDREW R COGGAN, LINDA Ruth PETERSON · 2023 to 2026
$2.9M
NHLBI NIH HHS R33 HL155858
6 · The paper itself

Abstract

INTRODUCTION/

aimsVoluntary muscle contractions result in a temporary increase in twitch force, a phenomenon termed post activation potentiation (PAP). In rodents and other species, PAP is observed predominantly or exclusively in fast twitch muscles. However, it has been suggested that in humans, PAP occurs more or less independently of muscle fiber type.

methodsEighteen healthy men and women (27 ± 8 years) underwent an electrical stimulation protocol during which two sets of four twitches were elicited both pre and post 6 s maximal voluntary contractions of the triceps surae (60%-70% slow twitch) and triceps brachii (60%-70% fast twitch) muscles.

resultsUnpotentiated peak twitch torque (PTT) was higher in the larger triceps surae versus the smaller triceps brachii (i.e., 13.4 ± 5.3 vs. 3.4 ± 2.1 nm; p < 0.001), but time to peak torque was shorter (i.e., 84 ± 7 vs. 132 ± 14 ms; p < 0.001) and relative rate of torque development (RTD) was greater in the triceps brachii (2294 ± 257 vs. 1425% ± 102%/s; p < 0.001). PAP increased PTT by 172% ± 124% in the triceps brachii versus 20% ± 20% in the triceps surae (p < 0.001). Absolute RTD also increased more in the triceps brachii (i.e., 240% ± 170% vs. 31% ± 24%; p < 0.001). However, PAP-induced changes in half-relaxation time and relative rate of relaxation did not differ between muscle groups. DISCUSSION: We conclude that PAP influences contraction but not relaxation of human muscle in a fiber type dependent manner. This should be kept in mind when interpreting individual differences in the results of neuromuscular testing, response to varying warm-up protocols, etc.

Indexed as

Muscle ContractionMuscle, SkeletalAdultElectric StimulationElectromyographyFemaleForce PotentiationHumansMaleTorqueYoung Adultmuscle fiber typemyosin regulatory light chainneuromuscular electrical stimulationtwitch contractile properties

Identifiers

PMID41649381
PMCPMC13047951

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.