Unilateral Knee Flexion Test For Tennis | 4.08

Second Edition · Chapter 3 Assessment · Original Test · 4.08

Measure quadriceps flexibility one leg at a time by recording the distance from the heel to the buttock.

How To Perform The Test

  1. Place a mat on the floor and lie face down with the legs close together.
  2. Bend one knee and draw the heel toward the buttock. Grasp that ankle with the hand on the same side and pull the heel as close as comfortably possible.
  3. Keep the hip from rotating or moving out to the side to gain extra reach.
  4. Measure the heel-to-buttocks distance with a tape measure. Repeat on the other leg and record both sides.

Use the same body position and measurement points when retesting.

Photographic Examples

Retain the actual heel-to-buttock distance and measurement units. Two inches is 5.08 cm and 2.5 inches is 6.35 cm. The source lists two inches in both Good and Fair bands; state the boundary convention before comparing scores. Record pelvic and trunk positioning rather than changing it to reduce the apparent gap.

The images illustrate the book’s Good, Fair and Poor positions. Shoes, camera angle and perspective can affect apparent distance, so use a tape measure for the result. Confirm that the hip stays aligned throughout.

Good-range knee flexion position with the heel drawn close to the buttock during a prone quadriceps flexibility test
Good example: heel close to the buttock.
Fair-range knee flexion position with a moderate gap between heel and buttock
Fair example: an intermediate heel-to-buttock gap.
Poor-range knee flexion position with a larger gap between heel and buttock
Poor example: a larger gap remains.

Scoring From The Tennis Book

  • Good: heel within 2 inches (5.08 cm) of the buttock.
  • Fair: 2–2.5 inches (5.08–6.35 cm).
  • Poor: more than 2.5 inches (6.35 cm).

Measure and score each side separately. The test assesses quadriceps flexibility; do not use hip rotation or abduction to reduce the distance.

If Knee Flexion Is Limited

The tennis book recommends Buttocks Kicks, SL RDL & Quad Stretch, and Side-Lying Quad Stretch to improve range of motion. Target the more limited side and retest both legs with the same method.

Book Reference

4.08 Unilateral Knee Flexion, original reference retained in Chapter 3 of the Second Edition of Advanced Concepts of Strength & Conditioning for Tennis. Return to Fitness Assessment.