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

18. juli 2026 oppdatert av: 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.

Studieoversikt

Status

Fullført

Forhold

Intervensjon / Behandling

Detaljert 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.

Studietype

Observasjonsmessig

Registrering (Faktiske)

26

Kontakter og plasseringer

Denne delen inneholder kontaktinformasjon for de som utfører studien, og informasjon om hvor denne studien blir utført.

Studiesteder

  • Kina
    • Guangdong
      • Guangzhou, Guangdong, Kina, 510006
        • School of Physical Education and Sports Science, South China Normal University

Deltakelseskriterier

Forskere ser etter personer som passer til en bestemt beskrivelse, kalt kvalifikasjonskriterier. Noen eksempler på disse kriteriene er en persons generelle helsetilstand eller tidligere behandlinger.

Kvalifikasjonskriterier

Alder som er kvalifisert for studier

  • Voksen
  • Eldre voksen

Tar imot friske frivillige

Ja

Prøvetakingsmetode

Ikke-sannsynlighetsprøve

Studiepopulasjon

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

Denne delen gir detaljer om studieplanen, inkludert hvordan studien er utformet og hva studien måler.

Hvordan er studiet utformet?

Designdetaljer

Hva måler studien?

Primære resultatmål

Resultatmål
Tiltaksbeskrivelse
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

Samarbeidspartnere og etterforskere

Det er her du vil finne personer og organisasjoner som er involvert i denne studien.

Sponsor

South China Normal University

Publikasjoner og nyttige lenker

Den som er ansvarlig for å legge inn informasjon om studien leverer frivillig disse publikasjonene. Disse kan handle om alt relatert til studiet.

Hjelpsomme linker

Studierekorddatoer

Disse datoene sporer fremdriften for innsending av studieposter og sammendragsresultater til ClinicalTrials.gov. Studieposter og rapporterte resultater gjennomgås av National Library of Medicine (NLM) for å sikre at de oppfyller spesifikke kvalitetskontrollstandarder før de legges ut på det offentlige nettstedet.

Studer hoveddatoer

Studiestart (Faktiske)

7. oktober 2025

Primær fullføring (Faktiske)

10. januar 2026

Studiet fullført (Faktiske)

1. mai 2026

Datoer for studieregistrering

Først innsendt

15. juli 2026

Først innsendt som oppfylte QC-kriteriene

18. juli 2026

Først lagt ut (Faktiske)

22. juli 2026

Oppdateringer av studieposter

Sist oppdatering lagt ut (Faktiske)

22. juli 2026

Siste oppdatering sendt inn som oppfylte QC-kriteriene

18. juli 2026

Sist bekreftet

1. juli 2026

Mer informasjon

Begreper knyttet til denne studien

Nøkkelord

Andre studie-ID-numre

  • SCNU-SPT-2025-055

Plan for individuelle deltakerdata (IPD)

Planlegger du å dele individuelle deltakerdata (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.

Tilgangskriterier for IPD-deling

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 Støtteinformasjonstype

  • STUDY_PROTOCOL
  • SEVJE
  • CSR

Legemiddel- og utstyrsinformasjon, studiedokumenter

Studerer et amerikansk FDA-regulert medikamentprodukt

Nei

Studerer et amerikansk FDA-regulert enhetsprodukt

Nei

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