Evidence map›Paper›PMID 41140141›Full record

ArticleThe Journal of experimental biology2025

Frequency and leg stiffness adaptation in human vertical hopping before, during and after added load.

Luke N Jessup, Moira A Williams, Alex J Duman, Juwon Lee, Raksha S Konanur, Anne K Silverman, James M Finley, Monica A Daley, Alexandra S Voloshina

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in The Journal of experimental biology, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing 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

0 citing papers in PubMed.

No citing paper in PubMed yet.

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

9 authors.

Luke N JessupDepartment of Ecology & Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA.ORCID 0000-0001-8666-2360
Moira A WilliamsDepartment of Ecology & Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA.
Alex J DumanDepartment of Ecology & Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA.
Juwon LeeDivision of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90033, USA.
Raksha S KonanurDepartment of Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, CA 92697, USA.
Anne K SilvermanDepartment of Mechanical Engineering, Colorado School of Mines, Golden, CO 80401, USA.ORCID 0000-0002-2228-4548
James M FinleyDivision of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90033, USA.ORCID 0000-0003-2679-2221
Monica A DaleyDepartment of Ecology & Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA.ORCID 0000-0001-8584-2052
Alexandra S VoloshinaDepartment of Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, CA 92697, USA.ORCID 0000-0002-6422-4666

Funding

National Science Foundation NSF-2021832National Science Foundation NSF-2319710
6 · The paper itself

Abstract

Terrestrial animal gaits often use spring-like mechanics to enhance movement economy through elastic energy cycling. Hopping is a relatively simple, constrained task, yet retains essential features of bouncing gaits, requiring cyclic regulation of limb stiffness and generation of high muscle forces to support body weight and enable elastic energy cycling. We investigated how humans adjust hopping frequency and leg stiffness before, during and after experiencing added load. Eighteen participants hopped bipedally for 90 s per trial, with hop frequency and height unconstrained, while kinematic, ground reaction force and ankle muscle electromyographic (EMG) data were collected. We analysed mechanics across four conditions: initial body weight (BWi), two added mass trials (+10% and +20% BW) and final body weight (BWf). With added mass, participants increased leg stiffness and maintained a consistent hopping frequency (∼2.15 Hz); yet, when returning to BWf, the elevated leg stiffness was maintained and hopping frequency increased (to ∼2.36 Hz) and reduced centre of mass (CoM) work per hop. BWf adaptations were driven by greater ankle stiffness, leading to less ankle work. Adaptation rates were consistent across trials, with steady-state mechanics reached in ∼30-40 s. Muscle coactivation decreased following BWi. Triceps surae mean EMG was unchanged with added mass and reduced in BWf. Similar patterns of adaptation were observed in bouncing without an aerial phase. Substantial inter-individual variability was observed in preferred hopping mechanics and adaptation strategy. Together, added mass and increased task familiarity led participants to recalibrate their hopping strategy. Based on literature evidence, the adaptations may align with reduced metabolic cost.

Indexed as

Adaptation, PhysiologicalGaitLegAdultBiomechanical PhenomenaElectromyographyFemaleHumansMaleMuscle, SkeletalWeight-BearingYoung AdultBiomechanicsBouncingEnergyMassMechanical demandsOptimisation

Identifiers

PMID41140141
PMCPMC12752494

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

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.