IASTM vs. Static Stretching for Hamstring Tightness: Short- and Long-Term Effects (IASTM-HT)

November 1, 2026 updated by: GÖKHAN MARAŞ

Comparison of the Short- and Long-Term Effects of Static Stretching and Instrument-Assisted Soft Tissue Mobilization on Flexibility, Performance, and Pressure Pain Threshold in Individuals With Hamstring Tightness: A Randomized Controlled Trial

This study compares two treatments for people with tight hamstring muscles (the muscles at the back of the thigh): instrument-assisted soft tissue mobilization (IASTM) and static stretching. Both are commonly used by physical therapists to improve flexibility, but few studies have looked at their effects beyond a few days after treatment ends.

Forty-six adults with hamstring tightness will be randomly assigned to one of two groups. One group will receive IASTM, and the other will receive static stretching. Both treatments will be given 3 times per week for 4 weeks (12 sessions total).

Researchers will measure flexibility (knee extension range of motion), pressure pain threshold, and physical performance (vertical jump and single-leg hop distance) at three time points: before treatment, 3 days after the last session, and 8 weeks after treatment ends. The goal is to find out which treatment provides better short-term and longer-term benefits.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Hamstring muscle tightness is a common musculoskeletal condition that can limit hip and knee range of motion, reduce athletic and functional performance, and contribute to other conditions such as patellofemoral pain, patellar tendinopathy, and low back pain. Static stretching has long been used to address hamstring tightness, with systematic reviews suggesting that 6-8 weeks of regular stretching can produce lasting flexibility gains. Instrument-assisted soft tissue mobilization (IASTM) has more recently emerged as an alternative technique, with proposed mechanisms including controlled microtrauma that stimulates an inflammatory response and collagen remodeling in soft tissue.

Most existing studies comparing static stretching and IASTM for hamstring tightness have examined only single-session or short-term (immediate post-treatment) effects. Long-term follow-up data (≥8 weeks) are limited, making it difficult to determine whether treatment-related gains in flexibility, pain sensitivity, and functional performance are sustained over time.

This randomized controlled trial will enroll 46 participants with hamstring tightness, defined as hip flexion range of motion <65° on the Straight Leg Raise (SLR) test with no neurological signs. Participants will be randomly allocated (computer-generated randomization) to one of two equal groups (n=23 each):

Group 1 (IASTM): Participants will receive instrument-assisted soft tissue mobilization applied to the hamstring muscle group using a stainless-steel instrument, scanning technique, distal-to-proximal direction, for 5 minutes per session.

Group 2 (Static Stretching): Participants will receive manual static stretching of the hamstring muscle group, performed in 5 repetitions of 30 seconds of stretch followed by 30 seconds of rest (5 minutes total per session).

Both interventions will be delivered 3 times per week for 4 weeks (12 sessions total) by a physical therapist with over 10 years of clinical experience in orthopedic rehabilitation and manual therapy.

Outcome assessments will be performed by a blinded assessor independent of treatment delivery, at three time points: baseline (pre-treatment), short-term (3 days after the final session), and long-term (8 weeks after intervention completion). Outcome measures include:

  • Flexibility: knee extension range of motion during 90° hip flexion, measured with a digital inclinometer
  • Pressure pain threshold: measured with a digital algometer over the hamstring muscle bellies (biceps femoris, semitendinosus, semimembranosus)
  • Functional performance: vertical jump height and single-leg hop distance

Statistical analysis will include two-way repeated-measures ANOVA to assess time and group-by-time interaction effects, with Bonferroni-corrected post hoc comparisons where appropriate.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
46

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Turkey (Türkiye)
    • Konya
      • Kulu, Konya, Turkey (Türkiye)
        • Recruiting
        • Selcuk University, Kulu Faculty of Health Sciences

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Age 18 years or older
  • Hamstring tightness, defined as hip flexion range of motion <65° on the Straight Leg Raise (SLR) test, without neurological signs
  • No diagnosed chronic musculoskeletal or systemic disease
  • Signed informed consent form

Exclusion Criteria:

  • Previous trauma or surgical operation involving the lower extremity
  • Neurological symptoms radiating to one or both lower extremities due to hamstring injury, spinal pathology, or sciatic nerve involvement
  • Ankle instability
  • Pregnancy
  • Neurological signs elicited during the Straight Leg Raise (SLR) test
  • Hyperalgesia, hematoma, varicose veins, or active skin infection in the lower extremity

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: IASTM

Participants will receive instrument-assisted soft tissue mobilization (IASTM) applied to the hamstring muscle group using a stainless-steel instrument in a scanning technique, distal-to-proximal direction, for 5 minutes per session, 3 times per week for 4 weeks (12 sessions total).
Other: Instrument-Assisted Soft Tissue Mobilization

Participants will receive instrument-assisted soft tissue mobilization (IASTM) applied to the hamstring muscle group using a stainless-steel instrument in a scanning technique, distal-to-proximal direction, for 5 minutes per session, 3 times per week for 4 weeks (12 sessions total).
Active Comparator: Static Stretching

Participants will receive manual static stretching of the hamstring muscle group, performed in 5 repetitions of 30 seconds of stretch followed by 30 seconds of rest (5 minutes total per session), 3 times per week for 4 weeks (12 sessions total).
Other: Static Stretching

Participants will receive manual static stretching of the hamstring muscle group, performed in 5 repetitions of 30 seconds of stretch followed by 30 seconds of rest (5 minutes total per session), 3 times per week for 4 weeks (12 sessions total).

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in Knee Extension Range of Motion (Flexibility)
Time Frame: Baseline, 3 days after final session (short-term), and 8 weeks after intervention completion (long-term)

Knee extension range of motion during 90° hip flexion, measured with a digital inclinometer, as an indicator of hamstring flexibility.
Baseline, 3 days after final session (short-term), and 8 weeks after intervention completion (long-term)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
GÖKHAN MARAŞ

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Gokhan Maras, PT, PhD, Selcuk University, Kulu Faculty of Health Sciences

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 22, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 18, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 18, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 24, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 4, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 1, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IASTM-HAM-2026-01

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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