Feasibility of Velocity Loss-Based Volume Prescription During Constant-Load and Chain-Based Smith Machine Back Squats
18 juli 2026 uppdaterad 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.
Studieöversikt
Status
Avslutad
Betingelser
Intervention / Behandling
Detaljerad beskrivning
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.
Studietyp
Observationell
Inskrivning (Faktisk)
26
Kontakter och platser
Det här avsnittet innehåller kontaktuppgifter för dem som genomför studien och information om var denna studie genomförs.
Studieorter
-
-
Guangdong
-
Guangzhou, Guangdong, Kina, 510006
- School of Physical Education and Sports Science, South China Normal University
-
-
Deltagandekriterier
Forskare letar efter personer som passar en viss beskrivning, så kallade behörighetskriterier. Några exempel på dessa kriterier är en persons allmänna hälsotillstånd eller tidigare behandlingar.
Urvalskriterier
Åldrar som är berättigade till studier
- Vuxen
- Äldre vuxen
Tar emot friska volontärer
Ja
Testmetod
Icke-sannolikhetsprov
Studera befolkning
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.
Beskrivning
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
Det här avsnittet ger detaljer om studieplanen, inklusive hur studien är utformad och vad studien mäter.
Hur är studien utformad?
Designdetaljer
Vad mäter studien?
Primära resultatmått
Resultatmått |
Åtgärdsbeskrivning |
Tidsram |
|---|---|---|
|
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds
Tidsram: 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
Tidsram: 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
|
Samarbetspartners och utredare
Det är här du hittar personer och organisationer som är involverade i denna studie.
Sponsor
Publikationer och användbara länkar
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Användbara länkar
Studieavstämningsdatum
Dessa datum spårar framstegen för inlämningar av studieposter och sammanfattande resultat till ClinicalTrials.gov. Studieposter och rapporterade resultat granskas av National Library of Medicine (NLM) för att säkerställa att de uppfyller specifika kvalitetskontrollstandarder innan de publiceras på den offentliga webbplatsen.
Studera stora datum
Studiestart (Faktisk)
7 oktober 2025
Primärt slutförande (Faktisk)
10 januari 2026
Avslutad studie (Faktisk)
1 maj 2026
Studieregistreringsdatum
Först inskickad
15 juli 2026
Först inskickad som uppfyllde QC-kriterierna
18 juli 2026
Första postat (Faktisk)
22 juli 2026
Uppdateringar av studier
Senaste uppdatering publicerad (Faktisk)
22 juli 2026
Senaste inskickade uppdateringen som uppfyllde QC-kriterierna
18 juli 2026
Senast verifierad
1 juli 2026
Mer information
Termer relaterade till denna studie
Nyckelord
Andra studie-ID-nummer
- SCNU-SPT-2025-055
Plan för individuella deltagardata (IPD)
Planerar du att dela individuella deltagardata (IPD)?
JA
IPD-planbeskrivning
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Tidsram för IPD-delning
Individual participant data and supporting documents will become available after publication of the study results and will remain available for 5 years.
Kriterier för IPD Sharing Access
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-delning som stöder informationstyp
- STUDY_PROTOCOL
- SAV
- CSR
Läkemedels- och apparatinformation, studiedokument
Studerar en amerikansk FDA-reglerad läkemedelsprodukt
Nej
Studerar en amerikansk FDA-reglerad produktprodukt
Nej
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