Kraus-Weber Abdominal Strength Test 3 Calculator

What is the Kraus-Weber Abdominal Strength Test 3?

The Kraus-Weber Abdominal Strength Test 3 is part of the historic Kraus-Weber fitness test battery developed by Dr. Hans Kraus and Dr. Sonja Weber in the 1950s. This specific test assesses the strength of the psoas and lower abdominal muscles, which are crucial for core stability, athletic performance, and preventing lower back pain. The test requires participants to raise their straight legs 25cm (10 inches) off the ground while lying supine and hold this position for 10 seconds.

The Kraus-Weber tests gained national attention in 1955 when research revealed that 58% of American children failed at least one of the six tests, compared to only 9% of European children. This alarming finding led to the establishment of the President's Council on Physical Fitness and Sports. Today, the test remains a valuable screening tool for minimum muscular fitness, particularly relevant for athletes requiring strong core and hip flexor function.

Research by Robert J. Wood, PhD in Exercise Physiology from the University of Western Australia and founder of Topend Sports, indicates that lower abdominal and psoas strength correlates significantly with athletic performance in sports requiring explosive hip flexion, such as sprinting, jumping, and kicking. Athletes who pass this test demonstrate adequate core strength for the demands of competitive sport and show reduced risk of lower back injuries.

How to Perform the Kraus-Weber Test 3

Pre-test procedures are essential for accurate assessment and safety. Follow these detailed steps:

Starting Position

• Lie flat on your back (supine position) on a firm, flat surface
• Place hands behind your neck with fingers interlaced
• Extend both legs fully with knees straight
• Keep your lower back pressed against the surface
• Ensure proper body alignment with head, shoulders, and hips in contact with the ground

Test Execution

1. Timer Setup: Click "Start Timer" in the calculator above or have a partner ready with a stopwatch
2. Leg Raise: Immediately raise both legs together until your heels are 25cm (10 inches) above the ground
3. Maintain Straight Legs: Keep knees fully extended throughout the test - no bending allowed
4. Hold Position: Maintain this exact height for up to 10 seconds
5. End Test: Click "Stop & Calculate" when you can no longer hold the position, or complete the full 10 seconds

Common Mistakes to Avoid

• Bending Knees: Even slight knee flexion invalidates the test - legs must remain completely straight
• Leg Height Variation: Raising legs too high (easier) or too low (harder) affects test validity
• Arching Lower Back: Keep your lower back pressed to the floor to properly isolate the target muscles
• Holding Breath: Breathe normally throughout - breath-holding can artificially extend performance
• Using Momentum: Avoid swinging or jerking movements - use controlled muscle contraction

Understanding Your Test Results

Pass/Fail Criteria

The traditional Kraus-Weber scoring is binary: you either pass or fail. To pass the test, you must hold the position for the full 10 seconds with proper form. Failing even one of the six Kraus-Weber tests indicates below-minimum muscular fitness, suggesting increased risk for back problems and reduced athletic capacity.

Modified Scoring System (0-10 Points)

According to sports science expert Robert Wood, who has analyzed sports performance data for over 25 years, a modified scoring system provides more detailed feedback. Each second held equals one point, with a maximum of 10 points:

• 10 points (10 seconds): Pass - Excellent lower abdominal and psoas strength
• 7-9 points: Good strength with minor weaknesses to address
• 4-6 points: Moderate strength requiring targeted training
• 1-3 points: Significant weakness requiring immediate intervention
• 0 points: Unable to raise or hold legs - severe weakness

What Your Score Means for Athletic Performance

The Science Behind Lower Abdominal and Psoas Strength

Muscles Tested

The Kraus-Weber Test 3 primarily assesses two crucial muscle groups:

Psoas Major and Minor: These deep hip flexor muscles originate from the lumbar spine and insert on the femur. They're responsible for hip flexion during running, jumping, and kicking. Data compiled shows that athletes with strong psoas muscles generate 12-15% more power during sprint acceleration compared to those with weak hip flexors.

Lower Rectus Abdominis: The lower portion of the "six-pack" muscle helps stabilize the pelvis and works synergistically with the psoas. Research indicates that lower abdominal strength correlates with reduced incidence of lower back pain in athletes, with properly conditioned athletes showing 40% fewer back-related training interruptions.

Biomechanics of the Test

When you raise your straight legs with hands behind your head, you create a long lever arm that significantly challenges the hip flexors and lower abdominals. According to Robert J. Wood's research at Topend Sports, the straight-leg position increases the difficulty by approximately 300% compared to bent-knee exercises, making this an effective minimum standard test.

The 10-second hold requirement tests isometric strength endurance rather than just peak strength. This duration was specifically chosen by Drs. Kraus and Weber because it represents the minimum muscular fitness needed for daily activities and athletic movements requiring sustained core stability.

Sport-Specific Applications

Track and Field Athletes

Sprinters benefit dramatically from strong psoas muscles, which power the hip flexion phase of the running cycle. According to sports science expert Robert Wood, elite 100m sprinters consistently score 10/10 on this test, with psoas strength contributing to their explosive acceleration. High Jumpers and pole vaulters rely on the same muscles for the powerful leg drive during takeoff, with Olympic-level jumpers showing 15-20% stronger hip flexor performance than national-level competitors.

Training Focus: Sprint training 3-4 days per week with emphasis on acceleration drills. Include specific psoas strengthening through hanging leg raises with 2.5kg ankle weights once base strength is established.

Soccer and Football Players

Research shows that soccer players who pass the Kraus-Weber Test 3 generate significantly more kicking power - approximately 8-10% increase in ball velocity compared to those who fail. The psoas is the primary muscle driving the leg forward during the kicking motion. Position-Specific Standards:

• Strikers/Forwards: Should consistently hold 10+ seconds and work toward weighted variations
• Midfielders: Minimum 10 seconds required due to high running volume
• Defenders: 8-10 seconds acceptable but improvement recommended
• Goalkeepers: 7-10 seconds sufficient given different physical demands

Gymnastics and Dance

Gymnasts require exceptional core control, with elite performers typically holding 10+ seconds while adding 5-10kg ankle weights for training. The psoas and lower abs are critical for:

• Maintaining horizontal body positions on rings and parallel bars
• Executing V-sits and L-sits with perfect form
• Controlling leg movements during floor routines
• Supporting inverted positions and handstands

Data research indicates that gymnasts scoring below 10 seconds show increased risk of form breaks during competitions and higher rates of lower back strain.

Combat Sports

Boxing and MMA: Lower abdominal strength protects against body shots and supports rotational power generation. Fighters who pass this test demonstrate better core stability during exchanges. Wrestling: The psoas is crucial for shooting takedowns and defending against them, with Division I wrestlers averaging 10+ seconds consistently.

How to Improve Your Kraus-Weber Test 3 Score

Progressive Training Program (8-Week Protocol)

Weeks 1-2: Foundation Phase

• Dead Bugs: 3 sets of 10 reps per side, 3x per week. Lie on back, raise arms and bent knees to 90 degrees, slowly lower opposite arm and leg
• Bent-Knee Leg Raises: 3 sets of 8-12 reps. Start with knees bent to reduce difficulty
• Hollow Body Hold: 3 sets, hold for maximum time (start with 10-15 seconds)

Weeks 3-4: Progressive Overload

• Straight Leg Raises (Wall Assisted): 3 sets of 8 reps. Place hands under lower back for support
• Flutter Kicks: 3 sets of 30 seconds. Small, controlled leg movements at 25cm height
• Timed Test Practice: 2 sets of maximum hold time, 2x per week. Record results to track progress

Weeks 5-6: Strength Building

• Hanging Knee Raises: 3 sets of 10 reps. Progress toward straight leg raises
• Reverse Crunches: 3 sets of 15 reps with 2-second hold at top
• Kraus-Weber Hold Practice: 4 sets of 8-10 second holds, 3x per week

Weeks 7-8: Test Preparation & Peak

• Full Test Simulations: 3 attempts per session, 2x per week with 3-minute rest between attempts
• Psoas Strengthening: High knee marches with resistance band, 3 sets of 20 per leg
• Maintain Core Work: Continue hollow body holds and leg raises to maintain strength base

Key Training Principles

According to Robert Wood's analysis of training progressions, athletes typically improve their hold time by 1-2 seconds per week with consistent training. Those starting at 3-4 seconds can expect to pass the test (10 seconds) within 6-8 weeks. Athletes starting at 7-9 seconds often reach the passing standard within 2-3 weeks.

Safety Considerations and Contraindications

This test places significant stress on the lower back and hip flexors. If you experience sharp pain (rather than normal muscle fatigue) during the test, stop immediately. Pain radiating into the legs or sharp spinal pain indicates improper form or underlying issues requiring medical evaluation.

Medical Disclaimer

Test Accuracy and Validation