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Feasibility of Velocity Loss-Based Volume Prescription During Constant-Load and Chain-Based Smith Machine Back Squats

18. juli 2026 opdateret af: Zongwei Chen, South China Normal University
The goal of this observational study was to evaluate the feasibility of percentage of velocity loss (%VL)-based approaches for prescribing training volume during constant-load and chain-based Smith machine back squats. The study aimed to answer whether %VL can be expressed as the maximum number of repetitions (%Rep) in constant-load and chain-based Smith machine squats. Twenty-six resistance-trained men performed repetitions-to-failure tests under variable (VRT) and constant resistance training (CRT). The %Rep attained before reaching different levels of effort were compared between VRT and CRT across various loads and sessions. Furthermore, this study evaluated the influence of different factors on the predictive accuracy of the %Rep-%VL relationships. These findings will provide evidence-based evidence in prescribing and monitoring intra-set volume.

Studieoversigt

Status

Afsluttet

Betingelser

Intervention / Behandling

Detaljeret beskrivelse

The goal of this observational study was to evaluate the feasibility of percentage of velocity loss (%VL)-based approaches for prescribing training volume during constant-load and chain-based Smith machine back squats. The study aimed to answer whether %VL can be expressed as the maximum number of repetitions (%Rep) in constant-load and chain-based Smith machine squats. Twenty-six resistance-trained men performed repetitions-to-failure tests at 85%, 75%, and 65% of their constant-load one-repetition maximum (1RM) under variable (VRT; 40% of the total external load provided by chains) and constant resistance training (CRT; 0% chains). The %Rep attained before reaching low (10% VL), moderate (20% VL), and high (30% VL) levels of effort were compared between VRT and CRT across various loads and sessions. Furthermore, this study evaluated the influence of regression type (individual vs. general), load specificity (load-specific vs. multiple-load), and loading configuration (CRT vs. VRT) on the predictive accuracy of the %Rep-%VL relationships established in session 1 for estimating %Rep in session 2. These findings will provide evidence-based evidence in prescribing and monitoring intra-set volume.

Undersøgelsestype

Observationel

Tilmelding (Faktiske)

26

Kontakter og lokationer

Dette afsnit indeholder kontaktoplysninger for dem, der udfører undersøgelsen, og oplysninger om, hvor denne undersøgelse udføres.

Studiesteder

  • Kina
    • Guangdong
      • Guangzhou, Guangdong, Kina, 510006
        • School of Physical Education and Sports Science, South China normal university

Deltagelseskriterier

Forskere leder efter personer, der passer til en bestemt beskrivelse, kaldet berettigelseskriterier. Nogle eksempler på disse kriterier er en persons generelle helbredstilstand eller tidligere behandlinger.

Berettigelseskriterier

Aldre berettiget til at studere

  • Voksen
  • Ældre voksen

Tager imod sunde frivillige

Ja

Prøveudtagningsmetode

Ikke-sandsynlighedsprøve

Studiebefolkning

Participant characteristics (mean ± standard deviation [range]) included: age, 20.4 ± 2.1 (18-25) years; body height, 1.78 ± 0.05 (1.68-1.87) m; body mass, 71.7 ± 7.5 (60.0-91.4) kg; training experience, 3.5 ± 1.8 (1-10) years; and constant-load 1RM, 135.4 ± 17.4 (95-163) kg, corresponding to 1.89 ± 0.21 (1.58-2.28) times body mass.

Beskrivelse

Inclusion Criteria:

  • at least 1 year of resistance training experience, performing back squats at least once per week.
  • proficiency in the Smith machine back squat executed at maximal intended velocity.
  • a constant-load 1RM of ≥ 1.5 times their body mass.
  • no reported musculoskeletal injuries in the past three months.

Exclusion Criteria:

  • Voluntary withdrawal or injury.
  • Not satisfied with inclusion label.

Studieplan

Dette afsnit indeholder detaljer om studieplanen, herunder hvordan undersøgelsen er designet, og hvad undersøgelsen måler.

Hvordan er undersøgelsen tilrettelagt?

Design detaljer

Hvad måler undersøgelsen?

Primære resultatmål

Resultatmål
Foranstaltningsbeskrivelse
Tidsramme
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds
Tidsramme: April 1st, 2026
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds was recorded across all loads, sessions, and loading configurations.
April 1st, 2026
The %rep predictive accuracy
Tidsramme: April 1st, 2026
To assess predictive accuracy, second-order polynomial regression equations were generated from the first session of each loading configuration using all repetitions within a set, setting %Rep as the dependent variable and %VL as the independent variable. These equations were constructed using different regression types (individual vs. general), load specificities (load-specific vs. multiple-load), and loading configurations (CRT vs. VRT). During the second session, the actual %VL recorded after reaching the 10%, 20%, and 30% VL thresholds was substituted into the corresponding first-session equations to derive the predicted %Rep. Then, the absolute estimation error was calculated as (|actual %Rep - predicted %Rep|). In cases where muscular failure occurred before a specific %VL threshold was reached (e.g., 30% VL), the %VL of the final completed repetition was recorded, and the corresponding actual %Rep was defined as 100%.
April 1st, 2026

Samarbejdspartnere og efterforskere

Det er her, du vil finde personer og organisationer, der er involveret i denne undersøgelse.

Sponsor

South China Normal University

Publikationer og nyttige links

Den person, der er ansvarlig for at indtaste oplysninger om undersøgelsen, leverer frivilligt disse publikationer. Disse kan handle om alt relateret til undersøgelsen.

Hjælpsomme links

Datoer for undersøgelser

Disse datoer sporer fremskridtene for indsendelser af undersøgelsesrekord og resumeresultater til ClinicalTrials.gov. Studieregistreringer og rapporterede resultater gennemgås af National Library of Medicine (NLM) for at sikre, at de opfylder specifikke kvalitetskontrolstandarder, før de offentliggøres på den offentlige hjemmeside.

Studer store datoer

Studiestart (Faktiske)

7. oktober 2025

Primær færdiggørelse (Faktiske)

10. januar 2026

Studieafslutning (Faktiske)

1. maj 2026

Datoer for studieregistrering

Først indsendt

15. juli 2026

Først indsendt, der opfyldte QC-kriterier

18. juli 2026

Først opslået (Faktiske)

22. juli 2026

Opdateringer af undersøgelsesjournaler

Sidste opdatering sendt (Faktiske)

22. juli 2026

Sidste opdatering indsendt, der opfyldte kvalitetskontrolkriterier

18. juli 2026

Sidst verificeret

1. juli 2026

Mere information

Begreber relateret til denne undersøgelse

Nøgleord

Andre undersøgelses-id-numre

  • SCNU-SPT-2025-055

Plan for individuelle deltagerdata (IPD)

Planlægger du at dele individuelle deltagerdata (IPD)?

JA

IPD-planbeskrivelse

The data that support the findings of this study are available from the corresponding author upon reasonable request.

IPD-delingstidsramme

Individual participant data and supporting documents will become available after publication of the study results and will remain available for 5 years.

IPD-delingsadgangskriterier

Individual participant data (IPD) will be shared in anonymized form with qualified researchers for scientific purposes. The shared data will include lifting velocity of each repetition completed.

IPD-deling Understøttende informationstype

  • STUDY_PROTOCOL
  • SAP
  • CSR

Lægemiddel- og udstyrsoplysninger, undersøgelsesdokumenter

Studerer et amerikansk FDA-reguleret lægemiddelprodukt

Ingen

Studerer et amerikansk FDA-reguleret enhedsprodukt

Ingen

Disse oplysninger blev hentet direkte fra webstedet clinicaltrials.gov uden ændringer. Hvis du har nogen anmodninger om at ændre, fjerne eller opdatere dine undersøgelsesoplysninger, bedes du kontakte register@clinicaltrials.gov. Så snart en ændring er implementeret på clinicaltrials.gov, vil denne også blive opdateret automatisk på vores hjemmeside .

Kliniske forsøg med Loading Configuration

Kliniske forsøg med variable resistance training

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