HealthyNCT04849923
Validation of a Digital Twin Performing Strength Training
A study testing Strength training session in people with Healthy, run by Silvio Lorenzetti at 1 site in Switzerland.
Trial summary
Background: Muscular strength training interventions have long been a cornerstone in the prevention, non-surgical management and rehabilitation of the entire spectrum of musculoskeletal injuries and diseases. Read more about this study
- Who is it for?
- Ages 20 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy
- What is being tested?
- Strength training session
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 23 participants
- Where
- 1 siteSwitzerland
- Study dates
- 1 Jan 2022to 27 Nov 2025
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 20 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy participants; and
- Age 20-40 years old; and
- No acute or chronic musculoskeletal symptoms or pain; and
- Experience with strength training (at least 1-year strength training experience with one training session per week or more); and
- Familiar with strength exercises of key muscles associated with knee joint stability.
Who cannot join
- Acute or chronic musculoskeletal pain; and/or
- Musculoskeletal surgery within the last 12 months; and/or
- Ongoing rehabilitation or treatment of musculoskeletal complaints or injury; and/or
- Neuromusculoskeletal disease (e.g. cerebral palsy); and/or
- Pregnancy.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Validation of a Digital Twin to Predict the Adaptation of Muscle Strength and Muscle Size Due to Strength Training
Background: Muscular strength training interventions have long been a cornerstone in the prevention, non-surgical management and rehabilitation of the entire spectrum of musculoskeletal injuries and diseases. The key goal of strength training, especially during rehabilitation, is to regain healthy musculoskeletal function. Yet, there remains a fundamental lack of understanding with regards to the relationship between subject-specific musculoskeletal biomechanics (i.e. multi-body dynamics function) and different types of strength training interventions because of limitations in assessing these parameters outside the research setting. Thus, clinicians, physiotherapists and coaches continue making training recommendations based on subjective and generalised guidelines, with ineffective or possibly harmful consequences for individual patients and athletes.
Goal: This project aims to advance strength training guidelines and monitoring of training safety and efficiency by means of subject-specific anatomically-based modelling, biomechanical analysis of musculoskeletal function and mobile monitoring of training volume and muscular fatigue in the athletic and recreational setting.
Read more
Method: For validation purposes, the investigators will conduct an 8-week intervention study in healthy volunteers with strength training of the key muscle-tendon groups associated with knee joint stability and relate the changes in musculoskeletal and biomechanical parameters to the training-specific parameters and muscular fatigue from mobile monitoring through correlation analysis.
Relevance: In Switzerland, more than 1.3 Mio people are members of a fitness center. Strength training is not only a cornerstone in the maintenance of fitness and rehabilitation from musculoskeletal injuries and diseases as the most frequently reported health issues.
Read the detailed description
Hypothesis: It is hypothesized that advanced subject-specific musculoskeletal modelling in combination with mobile monitoring technology as embedded in the iPhone and Apple Watch allow for accurate prediction of changes in muscle strength and muscle size in the lower limbs following an 8-week strength training intervention of key muscle-tendon groups associated with knee joint stability.
Primary Objective: Prediction of changes in muscle strength in the lower limbs by means of the advanced computational modelling, biomechanical analysis and mobile monitoring technology. Of particular interest is the prediction of 1RM, sprint time, CMJ and SJ. Research has clearly shown that the quantification of 1RM is fundamentally important when it comes to the design of safe and efficient resistance training programs.
Project design This project in sports science is designed as a confirmatory qualitative study in applied research involving healthy participants. The rationale of this project is to predict changes in muscle strength and muscle size due to strength training using computational modelling and mobile monitoring technology. In particular, the investigators will advance novel approaches in subject-specific anatomically-based modelling and mobile monitoring, which have previously tested in the research setting, and are now being applied to an intervention study in healthy volunteers to predict adaptations in muscle strength and function.
Study design: The specifics of the strength training intervention are carefully designed based on the current state of research in the field, and in line with strength training recommendations in musculoskeletal health, fitness and rehabilitation. In particular, the investigators will conduct an 8-week strength training intervention program of the key muscle-tendon groups associated with knee joint stability (hamstrings, quadriceps and triceps surae), with the study group (n=36, with 18F and 18M). Each participant will perform the strength training self-directedly in their chosen training-specific setting. Clear guidelines for warm-up, type and conduct of exercises will be given to all participants. The strength exercises are standard exercises for strengthening knee extension and flexion: squats, leg press, back extensions, heel raises, and single joint exercises.
Study parameters: Anthropometric parameters include body height, body weight. Strength- and training-specific parameters include repetition count, mean concentric velocity, 1RM, 5m and 20 sprint time, counter movement and squat jump and 1 RM.
PROJECT POPULATION AND STUDY PROCEDURES
Project population: The project population are healthy adult subjects who are all participating in their own strength training program on a regular weekly basis. The primary objective is to predict changes in muscle strength (i.e. primary outcome parameters: 1RM and H:Q ratio) following different training volumes of key muscle groups associated with knee joint stability. A power analysis was conducted using statistikguru.de to assess the required sample size for the primary outcome parameter, 1RM.
All participants have to confirm their voluntary participation with a written informed consent before being submitted to any study procedure.
- Conditions
- Healthy
- Being tested
- Strength training session
- Keywords
- strength training
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Strength training sessionOther
Also called resistance training
Conduct of an 6-week strength training intervention of key muscle-tendon groups associated with knee joint stability in the training-specific setting of each participant. Participants are asked to record exercise load and volume as well as monitor training-related variables and 1RM using the iOS Strength Control app. Participants perform the strength training self-directedly in their chosen fitness/training facilities as it fits into their weekly routine. Contact to the study investigator is ensured at all times in case of questions.
| Study group | Role | What they receive |
|---|---|---|
| 2 trainings per week | Experimental | This group performs two strength training sessions per week Receives: Other: Strength training session |
What is being measured
The primary outcome is the main question the study is designed to answer.
Stop-and-go (SAG) Ability
Change of the time for the stop and go task. Calculation: Post time minus pre time.
Measured: 8 weeks
20 m Sprint Performance
Change of the Sprint time, s
Measured: 8 weeks
Secondary outcomes (2)
Change in Jump Performance CMJ
Change of Countermovement jump (CMJ) height
Measured: 8 weeks
Changes in Jump Performance SJ
Change of the jump hight squat jump (SJ)
Measured: 8 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Apr 2021
- Study start1 Jan 2022
- Primary completion31 Oct 2025
- Study completion27 Nov 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for HealthyStudies 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Originally the study was planed with three arms, however it was conducted as single arm study.
- Masking
- None (open label)
- Enrolment
- 23 participants (actual)
Sponsor and investigators
- Lead sponsor
- Silvio Lorenzetti
- Sponsor type
- Other government
- Collaborators
- ZHAW School of Engineering
- Responsible party
- Sponsor-investigator, Silvio Lorenzetti, Swiss Federal Institute of Sport Magglingen
- Investigators
- Silvio Lorenzetti, Prof. Dr., Principal investigator, ZHAW School of Engineering
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04849923
- Sponsor's protocol ID
- Digital Twin
- Status last verified
- Aug 2026
- First submitted
- 13 Apr 2021
- Last updated
- 12 Aug 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Achermann BB, Regazzi N, Heynen R, Ludin D, Suter J, Drewek A, Lorenzetti SR. From Monitoring to Prediction: Velocity-Based Strength Training in Female Floorball Athletes. Sports (Basel). 2025 May 31;13(6):175. doi: 10.3390/sports13060175.
PubMed 40559687
Study at a glance
From the registry record, last updated by the sponsor on 12 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Validation of a Digital Twin to Predict the Adaptation of Muscle Strength and Muscle Size Due to Strength Training
- ClinicalTrials.gov ID
- NCT04849923
- Acronym / sponsor ID
- Digital Twin
- Conditions
- Healthy
- Keywords
- strength training
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 23 participants (actual)
- Lead sponsor
- Silvio LorenzettiOther government
- Collaborators
- ZHAW School of Engineering
- Study start
- 1 Jan 2022 (actual)
- Primary completion
- 31 Oct 2025 (actual)
- Study completion
- 27 Nov 2025 (actual)
- First posted
- 19 Apr 2021 (actual)
- Results
- Posted 6 May 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Background: Muscular strength training interventions have long been a cornerstone in the prevention, non-surgical management and rehabilitation of the entire spectrum of musculoskeletal injuries and diseases. The key goal of strength training, especially during rehabilitation, is to regain healthy musculoskeletal function. Yet, there remains a fundamental lack of understanding with regards to the relationship between subject-specific musculoskeletal biomechanics (i.e. multi-body dynamics function) and different types of strength training interventions because of limitations in assessing these parameters outside the research setting. Thus, clinicians, physiotherapists and coaches continue making training recommendations based on subjective and generalised guidelines, with ineffective or possibly harmful consequences for individual patients and athletes.
Goal: This project aims to advance strength training guidelines and monitoring of training safety and efficiency by means of subject-specific anatomically-based modelling, biomechanical analysis of musculoskeletal function and mobile monitoring of training volume and muscular fatigue in the athletic and recreational setting.
Method: For validation purposes, the investigators will conduct an 8-week intervention study in healthy volunteers with strength training of the key muscle-tendon groups associated with knee joint stability and relate the changes in musculoskeletal and biomechanical parameters to the training-specific parameters and muscular fatigue from mobile monitoring through correlation analysis.
Relevance: In Switzerland, more than 1.3 Mio people are members of a fitness center. Strength training is not only a cornerstone in the maintenance of fitness and rehabilitation from musculoskeletal injuries and diseases as the most frequently reported health issues.
Detailed description
Hypothesis: It is hypothesized that advanced subject-specific musculoskeletal modelling in combination with mobile monitoring technology as embedded in the iPhone and Apple Watch allow for accurate prediction of changes in muscle strength and muscle size in the lower limbs following an 8-week strength training intervention of key muscle-tendon groups associated with knee joint stability.
Primary Objective: Prediction of changes in muscle strength in the lower limbs by means of the advanced computational modelling, biomechanical analysis and mobile monitoring technology. Of particular interest is the prediction of 1RM, sprint time, CMJ and SJ. Research has clearly shown that the quantification of 1RM is fundamentally important when it comes to the design of safe and efficient resistance training programs.
Project design This project in sports science is designed as a confirmatory qualitative study in applied research involving healthy participants. The rationale of this project is to predict changes in muscle strength and muscle size due to strength training using computational modelling and mobile monitoring technology. In particular, the investigators will advance novel approaches in subject-specific anatomically-based modelling and mobile monitoring, which have previously tested in the research setting, and are now being applied to an intervention study in healthy volunteers to predict adaptations in muscle strength and function.
Study design: The specifics of the strength training intervention are carefully designed based on the current state of research in the field, and in line with strength training recommendations in musculoskeletal health, fitness and rehabilitation. In particular, the investigators will conduct an 8-week strength training intervention program of the key muscle-tendon groups associated with knee joint stability (hamstrings, quadriceps and triceps surae), with the study group (n=36, with 18F and 18M). Each participant will perform the strength training self-directedly in their chosen training-specific setting. Clear guidelines for warm-up, type and conduct of exercises will be given to all participants. The strength exercises are standard exercises for strengthening knee extension and flexion: squats, leg press, back extensions, heel raises, and single joint exercises.
Study parameters: Anthropometric parameters include body height, body weight. Strength- and training-specific parameters include repetition count, mean concentric velocity, 1RM, 5m and 20 sprint time, counter movement and squat jump and 1 RM.
PROJECT POPULATION AND STUDY PROCEDURES
Project population: The project population are healthy adult subjects who are all participating in their own strength training program on a regular weekly basis. The primary objective is to predict changes in muscle strength (i.e. primary outcome parameters: 1RM and H:Q ratio) following different training volumes of key muscle groups associated with knee joint stability. A power analysis was conducted using statistikguru.de to assess the required sample size for the primary outcome parameter, 1RM.
All participants have to confirm their voluntary participation with a written informed consent before being submitted to any study procedure.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Originally the study was planed with three arms, however it was conducted as single arm study.
| Arm | Type | Receives |
|---|---|---|
| 2 trainings per week | Experimental | Other: Strength training sessionThis group performs two strength training sessions per week |
Who may qualify
- Ages
- 20 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Healthy participants; and
- Age 20-40 years old; and
- No acute or chronic musculoskeletal symptoms or pain; and
- Experience with strength training (at least 1-year strength training experience with one training session per week or more); and
- Familiar with strength exercises of key muscles associated with knee joint stability.
Key exclusion criteria (5 listed)
- Acute or chronic musculoskeletal pain; and/or
- Musculoskeletal surgery within the last 12 months; and/or
- Ongoing rehabilitation or treatment of musculoskeletal complaints or injury; and/or
- Neuromusculoskeletal disease (e.g. cerebral palsy); and/or
- Pregnancy.
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 |
|---|---|---|
| Strength training sessionAlso: resistance trainingConduct of an 6-week strength training intervention of key muscle-tendon groups associated with knee joint stability in the training-specific setting of each participant. Participants are asked to record exercise load and volume as well as monitor training-related variables and 1RM using the iOS Strength Control app. Participants perform the strength training self-directedly in their chosen fitness/training facilities as it fits into their weekly routine. Contact to the study investigator is ensured at all times in case of questions. | Other | 2 trainings per week |
Primary outcome
Stop-and-go (SAG) Ability
Time frame: 8 weeks
Change of the time for the stop and go task. Calculation: Post time minus pre time.
20 m Sprint Performance
Time frame: 8 weeks
Change of the Sprint time, s
2 secondary outcomes
Change in Jump Performance CMJ
Time frame: 8 weeks
Changes in Jump Performance SJ
Time frame: 8 weeks
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Aug 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Results publication: PubMed 40559687Achermann BB, Regazzi N, Heynen R, Ludin D, Suter J, Drewek A, Lorenzetti SR. From Monitoring to Prediction: Velocity-Based Strength Training in Female Floorball Athletes. Sports (Basel). 2025 May 31;13(6):175. doi: 10.3390/sports13060175.
- Individual participant dataSharing planned: No
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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.
Silvio Lorenzetti, Prof. Dr. principal investigator
ZHAW School of Engineering
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Strength training session in people with Healthy, run by Silvio Lorenzetti at 1 site in Switzerland.
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 5 inclusion and 5 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 12 Aug 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 Switzerland. 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?
Yes. Results are posted in the registry (first posted 6 May 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Stop-and-go (SAG) Ability (time frame: 8 weeks). 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?
On the ClinicalTrials.gov record for NCT04849923, which also lists 1 linked publication.
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 12 Aug 2026.