Exercise TherapyNCT07398547
The Effect of Training Frequency on Explosive Strength in Adolescent Tennis Players During a Six-Week Functional Training Program
A study testing High-Frequency Functional Training Group (HFFT) and Low-Frequency Functional Training Group (LFFT) in people with Exercise Therapy, run by Biruni University at 1 site in Turkey (Türkiye).
Trial summary
Adolescence is a period characterized by rapid growth and development, characterized by intense structural, functional, and neuromuscular changes in the musculoskeletal system. The rapid height growth and proportional changes that occur during this period can negatively impact athletic performance by disrupting muscle… Read more about this study
- Who is it for?
- Ages 12 to 18 yearsHealthy volunteers can take part
- Conditions the study is for
- Exercise Therapy
- What is being tested?
- High-Frequency Functional Training Group (HFFT) and Low-Frequency Functional Training Group (LFFT)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 10 Feb 2026to 5 Apr 2026
- Phase
- Interventional
- 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 12 to 18 years
- All sexes
- Healthy volunteers accepted
- Child, Adult
Who may be able to join
- Adolescent tennis players aged 12-18 years.
- Have at least two years of regular tennis training history.
- Regularly practice tennis at least three days a week.
- Have not had an acute injury or surgery affecting the lower extremities in the last six months.
- Have the physical ability to fully complete explosive strength tests (CMJ, SJ, SLJ, RSI).
- Individuals who voluntarily agreed to participate in the study and provided written consent from their parents.
Who cannot join
- Those with ongoing pain, instability, or deformity in the knee, hip, ankle, or spine area.
- Those who have undergone a musculoskeletal physical therapy or rehabilitation program within the last 6 months.
- Those with a systemic disease that may affect neurological, vestibular, or balance.
- Those who experience pain or fatigue to the extent that they cannot complete postural analysis or performance tests.
- Those who do not have a regular sports history or have not trained regularly in the last 3 months.
- Participants who exhibited a lack of cooperation during the assessment process that could compromise measurement consistency.
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Sportplus Tennis Academy
Istanbul, Maltepe, 34844
About this study
Adolescence is a period characterized by rapid growth and development, characterized by intense structural, functional, and neuromuscular changes in the musculoskeletal system. The rapid height growth and proportional changes that occur during this period can negatively impact athletic performance by disrupting muscle strength and flexibility. Deficiencies in lower extremity muscle strength, in particular, can lead to decreased performance and increased injury risk in sports requiring high agility, balance, and explosive power, such as tennis.
Functional training programs are holistic exercise approaches that aim to improve neuromuscular control, balance, coordination, and muscle strength by simultaneously training multiple muscle groups. This type of training is particularly important in adolescent athletes because it supports the development of strength, endurance, and explosive power. Training frequency, in turn, plays a decisive role in muscle adaptation and performance enhancement by influencing the balance between loading and recovery.
Read more
Literature contains limited studies directly examining the effects of functional training frequency on explosive power performance in young athletes. Most existing research has focused on adult or professional athletes, and experimental studies comparing the effects of different training frequencies in adolescent tennis players are insufficient.
In this context, the aim of our study was to examine the effects of a six-week functional training program implemented at different training frequencies on lower extremity explosive strength parameters in adolescent tennis athletes.
Read the detailed description
Adolescence is a dynamic period accompanied by rapid growth and development, characterized by intense structural, functional, and neuromuscular changes in the musculoskeletal system. During this period, weakness in the lower extremity muscles can lead to decreased performance and increased injury risk in sports requiring agility, balance, and explosive power, such as tennis.
Functional training programs are comprehensive exercise approaches that improve neuromuscular coordination, balance, and stabilization by simultaneously activating multiple muscle groups. These types of training are particularly important for young athletes because they support sport-specific movement patterns, increase muscle strength, and optimize the energy transfer chain. Training frequency is a key variable in determining muscle adaptation, recovery time, and load balance. Therefore, studies examining the effects of different training frequencies on explosive power development in young tennis athletes are of great scientific and practical value.
Healthy adolescent tennis players who volunteer to participate will be included in the study. After recording demographic and sport-specific information, participants' explosive strength performance will be assessed using the Countermovement Jump (CMJ), Squat Jump (SJ), Single Leg Jump (SLJ), and Reactive Strength Index (RSI) tests. Participants will be randomly assigned to two groups: the first group will participate in a 60-minute functional training program once a week, and the second group will participate in a 60-minute functional training program three times a week. The programs will last six weeks, and all sessions will be conducted by the same physiotherapist. Assessments will be conducted before and after the six-week training program. The study employed a two-group, pretest-posttest design. This study aims to demonstrate the effects of different training frequencies on explosive strength development in adolescent tennis athletes, contributing to the scientific basis of training plans for young athletes and to optimize performance.
- Conditions
- Exercise Therapy
- Being tested
- High-Frequency Functional Training Group (HFFT), Low-Frequency Functional Training Group (LFFT)
- Keywords
- adolescent tennis players, explosive strength, performance development, functional training
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
High-Frequency Functional Training Group (HFFT)Other
Also called exercise
Participants in this group performed the same functional training program three times per week for six consecutive weeks. Each 60-minute session followed the same structure as the low-frequency program and was conducted under identical supervision and environmental conditions.
Low-Frequency Functional Training Group (LFFT)Other
Also called exercise
Participants in this group performed the same functional training program once per week for six consecutive weeks. Each 60-minute session followed the same structure as the low-frequency program and was conducted under identical supervision and environmental conditions.
| Study group | Role | What they receive |
|---|---|---|
| Low-Frequency Functional Training Group (LFFT) | Other | Participants in this group performed the functional training program once per week for six consecutive weeks. Each session lasted approximately 60 minutes and included dynamic warm-up, multi-joint functional exercises, and cool-down activities supervised by the same physiotherapist. Receives: Other: Low-Frequency Functional Training Group (LFFT) |
| High-Frequency Functional Training Group (HFFT) | Experimental | Participants in this group performed the same functional training program three times per week for six consecutive weeks. Each 60-minute session followed the same structure as the low-frequency program and was conducted under identical supervision and environmental conditions. Receives: Other: High-Frequency Functional Training Group (HFFT) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Countermovement Jump Test (CMJ)
The participant performs a rapid squat from an upright position with hands on hips, followed by a maximum vertical jump. This assesses lower extremity explosive strength and elastic energy utilization.
Measured: 6 weeks
Squat Jump (SJ) Test
The participant is fixed in a position of approximately 90° flexion of the knee and hip joints, then performs a maximum vertical jump without using the arms. It measures pure concentric muscle strength.
Measured: 6 weeks
Reactive Strength Index (RSI) Test
It's typically performed using a drop jump protocol. The participant jumps onto the platform from a specific height and bounces back up as quickly as possible after contact with the ground. RSI is calculated based on jump height and ground contact time; it measures reactive strength and stretch-shortening cycle (SSC) effectiveness.
Measured: 6 weeks
Standing Long Jump (SLJ) Test
The participant stands with their feet parallel and jumps as far forward as possible using their arms. Lower extremity explosive strength is assessed by measuring the jump distance.
Measured: 6 weeks
Assessment of normal joint motion
The Normal Joint Motion Assessment (NJM) Test is an objective method used to measure joint range of motion. In the study, participants' hip and knee joint flexion and extension angles will be assessed using the NJM test using a universal goniometer. Measurements will be made using active range of motion, and each measurement will be repeated three times and averaged.
Measured: 6 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Feb 2026
- Study start10 Feb 2026
- Primary completion30 Mar 2026
- Study completion5 Apr 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Exercise TherapyStudies of the same condition, open and under way.
- More trials run by Biruni UniversityThe sponsor's other registered studies.
- 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Our study is designed as a prospective, two-group experimental study. Participants will be randomly assigned to two groups: the first group will participate in a 60-minute functional training program once a week, and the second group will participate in a 60-minute functional training program three times a week. At the end of the six-week program, the effects of training frequency will be assessed by comparing changes in explosive strength performance across groups.
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 30 participants (actual)
Sponsor and investigators
- Lead sponsor
- Biruni University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, alyildirim, Biruni University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07398547
- Sponsor's protocol ID
- 1071
- Status last verified
- Apr 2026
- First submitted
- 24 Jan 2026
- Last updated
- 28 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Axman S, Stausholm MB, Volk NR, Ferrauti A, Magnusson SP, Couppe C. Physical Performance Tests in 8008 Competitive Youth Tennis Players-A Systematic Review and Meta-Analysis of Normative Values. Eur J Sport Sci. 2025 Sep;25(9):e70023. doi: 10.1002/ejsc.70023.
PubMed 40884448Colomar J, Baiget E, Corbi F. Influence of Strength, Power, and Muscular Stiffness on Stroke Velocity in Junior Tennis Players. Front Physiol. 2020 Mar 6;11:196. doi: 10.3389/fphys.2020.00196. eCollection 2020.
PubMed 32210838Myer GD, Faigenbaum AD, Ford KR, Best TM, Bergeron MF, Hewett TE. When to initiate integrative neuromuscular training to reduce sports-related injuries and enhance health in youth? Curr Sports Med Rep. 2011 May-Jun;10(3):155-66. doi: 10.1249/JSR.0b013e31821b1442.
PubMed 21623307Fernandez-Fernandez J, Ulbricht A, Ferrauti A. Fitness testing of tennis players: how valuable is it? Br J Sports Med. 2014 Apr;48 Suppl 1(Suppl 1):i22-31. doi: 10.1136/bjsports-2013-093152.
PubMed 24668375Markovic G, Mikulic P. Neuro-musculoskeletal and performance adaptations to lower-extremity plyometric training. Sports Med. 2010 Oct 1;40(10):859-95. doi: 10.2165/11318370-000000000-00000.
PubMed 20836583Castro-Pinero J, Ortega FB, Artero EG, Girela-Rejon MJ, Mora J, Sjostrom M, Ruiz JR. Assessing muscular strength in youth: usefulness of standing long jump as a general index of muscular fitness. J Strength Cond Res. 2010 Jul;24(7):1810-7. doi: 10.1519/JSC.0b013e3181ddb03d.
PubMed 20555277Noyes FR, Barber SD, Mangine RE. Abnormal lower limb symmetry determined by function hop tests after anterior cruciate ligament rupture. Am J Sports Med. 1991 Sep-Oct;19(5):513-8. doi: 10.1177/036354659101900518.
PubMed 1962720
Study at a glance
From the registry record, last updated by the sponsor on 28 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Training Frequency on Explosive Strength in Adolescent Tennis Players During a Six-Week Functional Training Program
- ClinicalTrials.gov ID
- NCT07398547
- Acronym / sponsor ID
- 1071
- Conditions
- Exercise Therapy
- Keywords
- adolescent tennis players, explosive strength, performance development, functional training
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 30 participants (actual)
- Lead sponsor
- Biruni UniversityUniversity, hospital or other
- Study start
- 10 Feb 2026 (actual)
- Primary completion
- 30 Mar 2026 (actual)
- Study completion
- 5 Apr 2026 (actual)
- First posted
- 10 Feb 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.
Adolescence is a period characterized by rapid growth and development, characterized by intense structural, functional, and neuromuscular changes in the musculoskeletal system. The rapid height growth and proportional changes that occur during this period can negatively impact athletic performance by disrupting muscle strength and flexibility. Deficiencies in lower extremity muscle strength, in particular, can lead to decreased performance and increased injury risk in sports requiring high agility, balance, and explosive power, such as tennis.
Functional training programs are holistic exercise approaches that aim to improve neuromuscular control, balance, coordination, and muscle strength by simultaneously training multiple muscle groups. This type of training is particularly important in adolescent athletes because it supports the development of strength, endurance, and explosive power. Training frequency, in turn, plays a decisive role in muscle adaptation and performance enhancement by influencing the balance between loading and recovery.
Literature contains limited studies directly examining the effects of functional training frequency on explosive power performance in young athletes. Most existing research has focused on adult or professional athletes, and experimental studies comparing the effects of different training frequencies in adolescent tennis players are insufficient.
In this context, the aim of our study was to examine the effects of a six-week functional training program implemented at different training frequencies on lower extremity explosive strength parameters in adolescent tennis athletes.
Detailed description
Adolescence is a dynamic period accompanied by rapid growth and development, characterized by intense structural, functional, and neuromuscular changes in the musculoskeletal system. During this period, weakness in the lower extremity muscles can lead to decreased performance and increased injury risk in sports requiring agility, balance, and explosive power, such as tennis.
Functional training programs are comprehensive exercise approaches that improve neuromuscular coordination, balance, and stabilization by simultaneously activating multiple muscle groups. These types of training are particularly important for young athletes because they support sport-specific movement patterns, increase muscle strength, and optimize the energy transfer chain. Training frequency is a key variable in determining muscle adaptation, recovery time, and load balance. Therefore, studies examining the effects of different training frequencies on explosive power development in young tennis athletes are of great scientific and practical value.
Healthy adolescent tennis players who volunteer to participate will be included in the study. After recording demographic and sport-specific information, participants' explosive strength performance will be assessed using the Countermovement Jump (CMJ), Squat Jump (SJ), Single Leg Jump (SLJ), and Reactive Strength Index (RSI) tests. Participants will be randomly assigned to two groups: the first group will participate in a 60-minute functional training program once a week, and the second group will participate in a 60-minute functional training program three times a week. The programs will last six weeks, and all sessions will be conducted by the same physiotherapist. Assessments will be conducted before and after the six-week training program. The study employed a two-group, pretest-posttest design. This study aims to demonstrate the effects of different training frequencies on explosive strength development in adolescent tennis athletes, contributing to the scientific basis of training plans for young athletes and to optimize performance.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
- Model description
- Our study is designed as a prospective, two-group experimental study. Participants will be randomly assigned to two groups: the first group will participate in a 60-minute functional training program once a week, and the second group will participate in a 60-minute functional training program three times a week. At the end of the six-week program, the effects of training frequency will be assessed by comparing changes in explosive strength performance across groups.
| Arm | Type | Receives |
|---|---|---|
| Low-Frequency Functional Training Group (LFFT) | Other | Other: Low-Frequency Functional Training Group (LFFT)Participants in this group performed the functional training program once per week for six consecutive weeks. Each session lasted approximately 60 minutes and included dynamic warm-up, multi-joint functional exercises, and cool-down activities supervised by the same physiotherapist. |
| High-Frequency Functional Training Group (HFFT) | Experimental | Other: High-Frequency Functional Training Group (HFFT)Participants in this group performed the same functional training program three times per week for six consecutive weeks. Each 60-minute session followed the same structure as the low-frequency program and was conducted under identical supervision and environmental conditions. |
Who may qualify
- Ages
- 12 to 18 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult
Key inclusion criteria (6 listed)
- Adolescent tennis players aged 12-18 years.
- Have at least two years of regular tennis training history.
- Regularly practice tennis at least three days a week.
- Have not had an acute injury or surgery affecting the lower extremities in the last six months.
- Have the physical ability to fully complete explosive strength tests (CMJ, SJ, SLJ, RSI).
Key exclusion criteria (6 listed)
- Those with ongoing pain, instability, or deformity in the knee, hip, ankle, or spine area.
- Those who have undergone a musculoskeletal physical therapy or rehabilitation program within the last 6 months.
- Those with a systemic disease that may affect neurological, vestibular, or balance.
- Those who experience pain or fatigue to the extent that they cannot complete postural analysis or performance tests.
- Those who do not have a regular sports history or have not trained regularly in the last 3 months.
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 |
|---|---|---|
| High-Frequency Functional Training Group (HFFT)Also: exerciseParticipants in this group performed the same functional training program three times per week for six consecutive weeks. Each 60-minute session followed the same structure as the low-frequency program and was conducted under identical supervision and environmental conditions. | Other | High-Frequency Functional Training Group (HFFT) |
| Low-Frequency Functional Training Group (LFFT)Also: exerciseParticipants in this group performed the same functional training program once per week for six consecutive weeks. Each 60-minute session followed the same structure as the low-frequency program and was conducted under identical supervision and environmental conditions. | Other | Low-Frequency Functional Training Group (LFFT) |
Primary outcome
Countermovement Jump Test (CMJ)
Time frame: 6 weeks
The participant performs a rapid squat from an upright position with hands on hips, followed by a maximum vertical jump. This assesses lower extremity explosive strength and elastic energy utilization.
Squat Jump (SJ) Test
Time frame: 6 weeks
The participant is fixed in a position of approximately 90° flexion of the knee and hip joints, then performs a maximum vertical jump without using the arms. It measures pure concentric muscle strength.
Reactive Strength Index (RSI) Test
Time frame: 6 weeks
It's typically performed using a drop jump protocol. The participant jumps onto the platform from a specific height and bounces back up as quickly as possible after contact with the ground. RSI is calculated based on jump height and ground contact time; it measures reactive strength and stretch-shortening cycle (SSC) effectiveness.
Standing Long Jump (SLJ) Test
Time frame: 6 weeks
The participant stands with their feet parallel and jumps as far forward as possible using their arms. Lower extremity explosive strength is assessed by measuring the jump distance.
Assessment of normal joint motion
Time frame: 6 weeks
The Normal Joint Motion Assessment (NJM) Test is an objective method used to measure joint range of motion. In the study, participants' hip and knee joint flexion and extension angles will be assessed using the NJM test using a universal goniometer. Measurements will be made using active range of motion, and each measurement will be repeated three times and averaged.
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 28 Apr 2026.
- Results publication: PubMed 40884448Axman S, Stausholm MB, Volk NR, Ferrauti A, Magnusson SP, Couppe C. Physical Performance Tests in 8008 Competitive Youth Tennis Players-A Systematic Review and Meta-Analysis of Normative Values. Eur J Sport Sci. 2025 Sep;25(9):e70023. doi: 10.1002/ejsc.70023.
- Results publication: PubMed 32210838Colomar J, Baiget E, Corbi F. Influence of Strength, Power, and Muscular Stiffness on Stroke Velocity in Junior Tennis Players. Front Physiol. 2020 Mar 6;11:196. doi: 10.3389/fphys.2020.00196. eCollection 2020.
- Results publication: PubMed 21623307Myer GD, Faigenbaum AD, Ford KR, Best TM, Bergeron MF, Hewett TE. When to initiate integrative neuromuscular training to reduce sports-related injuries and enhance health in youth? Curr Sports Med Rep. 2011 May-Jun;10(3):155-66. doi: 10.1249/JSR.0b013e31821b1442.
- Results publication: PubMed 24668375Fernandez-Fernandez J, Ulbricht A, Ferrauti A. Fitness testing of tennis players: how valuable is it? Br J Sports Med. 2014 Apr;48 Suppl 1(Suppl 1):i22-31. doi: 10.1136/bjsports-2013-093152.
- Results publication: PubMed 20836583Markovic G, Mikulic P. Neuro-musculoskeletal and performance adaptations to lower-extremity plyometric training. Sports Med. 2010 Oct 1;40(10):859-95. doi: 10.2165/11318370-000000000-00000.
- Results publication: PubMed 20555277Castro-Pinero J, Ortega FB, Artero EG, Girela-Rejon MJ, Mora J, Sjostrom M, Ruiz JR. Assessing muscular strength in youth: usefulness of standing long jump as a general index of muscular fitness. J Strength Cond Res. 2010 Jul;24(7):1810-7. doi: 10.1519/JSC.0b013e3181ddb03d.
- Results publication: PubMed 1962720Noyes FR, Barber SD, Mangine RE. Abnormal lower limb symmetry determined by function hop tests after anterior cruciate ligament rupture. Am J Sports Med. 1991 Sep-Oct;19(5):513-8. doi: 10.1177/036354659101900518.
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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.
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?
A study testing High-Frequency Functional Training Group (HFFT) and Low-Frequency Functional Training Group (LFFT) in people with Exercise Therapy, run by Biruni University at 1 site in Turkey (Türkiye).
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 6 inclusion and 6 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 28 Apr 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 Turkey (Türkiye). 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?
Countermovement Jump Test (CMJ) (time frame: 6 weeks). The study lists 5 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 NCT07398547, which also lists 7 linked publications.
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 28 Apr 2026.