Loading ConfigurationNCT07719010
Feasibility of Velocity Loss-Based Volume Prescription During Constant-Load and Chain-Based Smith Machine Back Squats
An observational study of Loading Configuration and Levels of Effort, run by South China Normal University at 1 site in China.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older, men onlyHealthy volunteers can take part
- Conditions the study is for
- Loading Configuration, Levels of Effort
- What is being tested?
- variable resistance training and constant resistance training
- How many people
- 26 participants
- Where
- 1 siteChina
- Study dates
- 7 Oct 2025to 1 May 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- Men only
- Healthy volunteers accepted
- Adult, Older adult
Study population: 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.
Who may be able to join
- 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.
Who cannot join
- Voluntary withdrawal or injury.
- Not satisfied with inclusion label.
Trial locations and contacts
1 site in 1 country.
China1 site
School of Physical Education and Sports Science, South China normal university
Guangzhou, Guangdong, 510006
About this study
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.
Read the detailed description
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.
- Conditions
- Loading Configuration, Levels of Effort
- Being tested
- variable resistance training, constant resistance training
- Keywords
- level of effort, lifting velocity, training volume, velocity-based training, variable resistance training
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
variable resistance trainingOther
Participants initially completed a standardized general warm-up and a specific warm-up. The specific warm-up protocol included 3 repetitions at approximately 40% 1RM, 2 repetitions at 65% 1RM, and 1 repetition at 90% 1RM using constant-load to ensure adequate neuromuscular activation for the subsequent testing sets. After a 3-minute rest, participants performed three sets to momentary muscular failure with 40% of total external loads provided by chains. To minimize fatigue from higher-repetition sets influencing the repetitions completed in subsequent loads, the loads were not tested in a randomized order. Instead, participants performed the tests in a descending order of 85%, 75%, and 65% 1RM.
constant resistance trainingOther
Participants initially completed a standardized general warm-up and a specific warm-up. The specific warm-up protocol included 3 repetitions at approximately 40% 1RM, 2 repetitions at 65% 1RM, and 1 repetition at 90% 1RM using constant-load to ensure adequate neuromuscular activation for the subsequent testing sets. After a 3-minute rest, participants performed three sets to momentary muscular failure with 0% of total external loads provided by chains. To minimize fatigue from higher-repetition sets influencing the repetitions completed in subsequent loads, the loads were not tested in a randomized order. Instead, participants performed the tests in a descending order of 85%, 75%, and 65% 1RM.
What is being measured
The primary outcome is the main question the study is designed to answer.
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds was recorded across all loads, sessions, and loading configurations.
Measured: April 1st, 2026
The %rep predictive accuracy
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%.
Measured: April 1st, 2026
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Jul 2026
- Study start7 Oct 2025
- Primary completion10 Jan 2026
- Study completion1 May 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Loading ConfigurationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case crossover
- Time perspective
- Cross-sectional
- Enrolment
- 26 participants (actual)
Sponsor and investigators
- Lead sponsor
- South China Normal University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Zongwei Chen, South China Normal University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07719010
- Sponsor's protocol ID
- SCNU-SPT-2025-055
- Status last verified
- Jul 2026
- First submitted
- 15 Jul 2026
- Last updated
- 22 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: The data that support the findings of this study are available from the corresponding author upon reasonable request.
Study at a glance
From the registry record, last updated by the sponsor on 22 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Feasibility of Velocity Loss-Based Volume Prescription During Constant-Load and Chain-Based Smith Machine Back Squats
- ClinicalTrials.gov ID
- NCT07719010
- Acronym / sponsor ID
- SCNU-SPT-2025-055
- Conditions
- Loading Configuration, Levels of Effort
- Keywords
- level of effort, lifting velocity, training volume, velocity-based training, variable resistance training
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 26 participants (actual)
- Lead sponsor
- South China Normal UniversityUniversity, hospital or other
- Study start
- 7 Oct 2025 (actual)
- Primary completion
- 10 Jan 2026 (actual)
- Study completion
- 1 May 2026 (actual)
- First posted
- 22 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
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.
Study design
- Observational model
- Case crossover
- Time perspective
- Cross-sectional
Who may qualify
- Ages
- 18 years and older
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- 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.
Key inclusion criteria (4 listed)
- 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.
Key exclusion criteria (2 listed)
- Voluntary withdrawal or injury.
- Not satisfied with inclusion label.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| variable resistance trainingParticipants initially completed a standardized general warm-up and a specific warm-up. The specific warm-up protocol included 3 repetitions at approximately 40% 1RM, 2 repetitions at 65% 1RM, and 1 repetition at 90% 1RM using constant-load to ensure adequate neuromuscular activation for the subsequent testing sets. After a 3-minute rest, participants performed three sets to momentary muscular failure with 40% of total external loads provided by chains. To minimize fatigue from higher-repetition sets influencing the repetitions completed in subsequent loads, the loads were not tested in a randomized order. Instead, participants performed the tests in a descending order of 85%, 75%, and 65% 1RM. | Other | – |
| constant resistance trainingParticipants initially completed a standardized general warm-up and a specific warm-up. The specific warm-up protocol included 3 repetitions at approximately 40% 1RM, 2 repetitions at 65% 1RM, and 1 repetition at 90% 1RM using constant-load to ensure adequate neuromuscular activation for the subsequent testing sets. After a 3-minute rest, participants performed three sets to momentary muscular failure with 0% of total external loads provided by chains. To minimize fatigue from higher-repetition sets influencing the repetitions completed in subsequent loads, the loads were not tested in a randomized order. Instead, participants performed the tests in a descending order of 85%, 75%, and 65% 1RM. | Other | – |
Primary outcome
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds
Time frame: April 1st, 2026
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds was recorded across all loads, sessions, and loading configurations.
The %rep predictive accuracy
Time frame: 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%.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Jul 2026.
- Related InfoLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. The data that support the findings of this study are available from the corresponding author upon reasonable request.
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Loading Configuration and Levels of Effort, run by South China Normal University at 1 site in China.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 22 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in China. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds (time frame: April 1st, 2026). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Jul 2026.