The Isometric Mid-Thigh Pull (IMTP) test is a gold-standard assessment for measuring maximum force production in athletes. This IMTP calculator helps you analyze your test results by calculating net peak force, relative force, and rate of force development metrics, then comparing them to sport-specific normative data from peer-reviewed research.

Isometric Leg Strength Test / Mid-Thigh Pull Test (IMTP)

Isometric Leg Strength Test / Mid-Thigh Pull (IMTP)

When performed on a force plate, the IMTP can quantify peak force, relative force (N/kg), time to peak force, and rate of force development (RFD). Research shows the IMTP correlates strongly with athletic performance measures including vertical jump height (r = 0.346-0.674), sprint speed, change of direction ability, and power clean 1RM.

Equipment required: Strength dynamometer, usually composed of a cable tensiometer, force plate (optional).

Pre-test: Explain the test procedures to the subject. Perform screening of health risks and obtain informed consent. Prepare forms and record basic information such as age, height, body weight, gender and test conditions. Check and calibrate the equipment if required. See more details of pre-test procedures.

How to Use This IMTP Calculator

Follow these steps to analyze your isometric mid-thigh pull test results:

1. Enter Peak Force

Input your maximum force reading from the dynamometer or force plate in Newtons (N). This is the highest force recorded during your 3-5 second maximal pull effort.

2. Enter Body Weight

Input your body weight measured before testing. Toggle between metric (kg) and imperial (lbs) units as needed. Accurate body weight is essential for relative force calculations.

3. Select Your Level

Choose your competition level from recreational to professional. This determines which normative data is used for benchmarking your performance.

4. View Your Results

Click Calculate to see your net peak force, relative force (N/kg), body weight multiple, performance category, and sport-specific comparisons.

Understanding Your IMTP Results

The calculator provides several key metrics to evaluate your isometric strength:

Net Peak Force

Net peak force is calculated by subtracting your body weight (converted to Newtons) from peak force. The formula is: Net PF = Peak Force - (Body Weight × 9.81). This metric provides a more accurate comparison between athletes of different sizes and is the preferred measure used by sports scientists at facilities like Driveline Baseball, where they target net peak force above 3000N for competitive athletes.

Relative Force (N/kg)

Relative force normalizes your peak force to body mass, calculated as: Relative Force = Peak Force ÷ Body Weight (kg). This allows fair comparison between athletes of different sizes. Professional soccer players typically achieve 37-38 N/kg, while youth players average around 34 N/kg based on research from English Football League academies.

Body Weight Multiple

This represents how many times your body weight you can produce in force. Elite athletes typically achieve 3× body weight or higher, with well-trained male adults ranging from 2.5-3.5× body weight. Female athletes typically range from 2.0-3.0× body weight when trained.

IMTP Normative Data by Population

The following table presents normative data compiled from peer-reviewed research on isometric mid-thigh pull performance across different athletic populations:

Population Peak Force (N) Relative Force (N/kg) Body Weight Multiple
Professional Rugby 2254-3851 25-40 2.5-4.0×
Professional Soccer 3031 ± 549 37.4 ± 5.4 3.0-3.8×
Youth Soccer (Academy) 2441 ± 452 34.0 ± 4.7 2.5-3.5×
Collegiate Athletes 2500-3500 30-40 2.5-3.5×
Youth Male Athletes 1162-2374 25-35 1.5-2.5×
Youth Female Athletes 1000-2000 20-30 1.3-2.2×
Trained Adults (Male) 2500-4000+ 30-45 2.5-3.5×
Trained Adults (Female) 1800-3000 25-38 2.0-3.0×

Data sources: Comfort et al. (2019), Drake et al. (2018), Morris et al. (2020), McMahon et al. (2017)

The Science Behind the IMTP Test

The isometric mid-thigh pull has become a gold-standard assessment in sports science since its development in the early 1990s. Research from experts including Dr. Michael Stone at East Tennessee State University and Dr. Paul Comfort at the University of Salford has established its validity and reliability for measuring maximum isometric force.

Why the IMTP Works

A maximal isometric contraction allows individuals to produce greater force than a maximal concentric action. This makes the IMTP a true measure of maximum force generation capacity. The test position—mimicking the second pull position of the clean—recruits the major muscle groups involved in athletic movements: quadriceps, hamstrings, gluteals, and back extensors.

Test Reliability

A systematic review of 16 studies found excellent test-retest reliability for the IMTP, with intraclass correlation coefficients (ICC) ranging from 0.73-0.99 (median 0.96) and coefficients of variation (CV) from 0.7-11.1% (median 4.9%). Peak force measurements show the highest reliability, making them the primary metric for athlete monitoring.

Correlations with Performance

Research demonstrates significant correlations between IMTP force-time characteristics and athletic performance:

  • Power Clean 1RM: r = 0.569-0.674 (large correlation)
  • Countermovement Jump Height: r = 0.346 (moderate correlation)
  • Sprint Acceleration: significant positive correlation with RFD
  • Change of Direction: moderate correlation with time-specific force values

IMTP Test Protocol

For accurate and reliable results, follow this standardized IMTP protocol based on recommendations from Comfort et al. (2019):

Equipment Setup

Position the barbell at mid-thigh height when standing in a slight Romanian deadlift position. Use a force plate sampling at 1000 Hz minimum. Knee angle should be 125-145° with hip angle at 145-150°.

Body Position

Stand with feet shoulder-width apart, knees bent at approximately 110-125°, back slightly flexed at the hips, head upright looking straight ahead. Use a clean grip or alternating grip with straps if needed.

Warm-Up Protocol

Perform general warm-up with bodyweight squats and lunges, followed by submaximal pulls at 50%, 75%, and 90% perceived effort. Allow 60 seconds rest between warm-up pulls.

Test Execution

Stand still for 1-2 second baseline, then pull maximally for 3-5 seconds. Cue athletes to "push feet into the ground" rather than "pull up on the bar." Perform minimum 2 maximal trials with 2-3 minutes rest.

Sport-Specific Applications

Rugby

Professional rugby players show peak forces ranging from 2254-3851N, with rate of force development (RFD) at 100ms ranging from 5521-11,892 N/s. The IMTP correlates with tackling ability and scrummaging force, making it valuable for position-specific training programming.

Soccer/Football

Research on English Football League players shows professional players produce significantly greater peak force (3031 ± 549N) and relative force (37.4 ± 5.4 N/kg) than academy players. The IMTP can help identify talent and track physical development through academy levels.

Baseball

Facilities like Driveline Baseball use the IMTP to assess lower body strength in pitchers and position players. They target net peak force above 3000N and relative strength above 3× body weight as benchmarks for competitive athletes.

Olympic Weightlifting

The IMTP has over 25 years of research application in weightlifting. The test position mimics the second pull of the clean, making it directly applicable to competitive performance. Elite weightlifters often exceed 4000N peak force.

How to Improve Your IMTP Results

Based on your calculated performance category, consider these evidence-based training recommendations:

If Below Average (Under 2.5× BW)

  • Focus on basic strength development with compound movements
  • Prioritize back squat, deadlift, and Romanian deadlift progressions
  • Train 3-4× per week with progressive overload
  • Target 4-8 reps for strength development

If Average to Good (2.5-3.0× BW)

  • Maintain strength base while adding power development
  • Include Olympic lift variations (power clean, hang clean)
  • Add isometric training at specific joint angles
  • Consider speed-strength exercises (jump squats, trap bar jumps)

If Excellent to Elite (Above 3.0× BW)

  • Focus on rate of force development training
  • Include ballistic and plyometric exercises
  • Use contrast training methods
  • Maintain strength while improving power output

Frequently Asked Questions

What is a good IMTP peak force for athletes?

Elite athletes typically produce peak forces above 3000N or 3× body weight. Professional soccer players average around 3031N (37.4 N/kg), while youth athletes range from 2000-2500N. The threshold for competitive athletes is generally 3× body weight or greater.

How do you calculate relative force from IMTP?

Relative force is calculated by dividing peak force (in Newtons) by body weight (in kg). For example, if an athlete produces 3000N and weighs 80kg, their relative force is 37.5 N/kg. This can also be expressed as a body weight multiple by dividing by 9.81 (gravity), giving 3.83× body weight.

What is net peak force and why does it matter?

Net peak force equals peak force minus body weight (converted to Newtons: kg × 9.81). This metric removes the influence of body mass, providing a purer measure of muscular force production. It's particularly useful for tracking true strength gains independent of weight changes.

What knee angle should be used for the IMTP test?

Research recommends a knee angle of 125-145 degrees with a hip angle of 145-150 degrees. This "upright" position maximizes force production compared to more flexed positions. Consistent positioning between testing sessions is essential for reliable comparisons.

How reliable is the IMTP test for tracking athlete progress?

The IMTP demonstrates excellent reliability with ICCs of 0.84-0.99 (median 0.96) for peak force measurements. Coefficients of variation typically range from 0.7-11.1% (median 4.9%). Peak force is more reliable than time-dependent metrics like RFD, making it the preferred measure for longitudinal monitoring.

How does IMTP compare to 1RM testing?

The IMTP offers several advantages over traditional 1RM testing: it's safer with lower injury risk, requires less technical skill, produces more reliable results, causes less fatigue, and provides additional metrics like RFD. However, it measures isometric strength which may have limited transfer to dynamic movements in some contexts.

Can the IMTP predict athletic performance?

Research shows significant correlations between IMTP metrics and athletic performance. Peak force correlates with power clean 1RM (r = 0.57-0.67), and force at 250ms correlates with countermovement jump height (r = 0.35). RFD metrics correlate with sprint acceleration and change of direction ability.