How to do it
How do you do the Fire Hydrant?
- Start on all fours, hands under shoulders and knees under hips.
- Brace your stomach and keep your back flat.
- Keeping your knee bent, lift one leg out to the side.
- Pause, then lower your knee back under your hip.
- Finish your set, then switch legs.
Cues
- Hips stay level, like a table.
- Knee and foot rise together.
- Move only the leg, not your body.
Common mistakes
- Tipping your hips to lift the leg higher.
- Leaning your body away from the working leg.
- Letting your back sag.
Form in detail
What does good form look like?
Starting position
All fours on a mat. Hands flat, shoulder-width apart, directly under the shoulders, fingers forward, arms straight but not locked. Knees hip-width apart, directly under the hips, so hips and knees are both at about 90°. Tops of the feet on the floor. Back flat and roughly parallel to the floor, stomach braced, neck long with the eyes on the floor between the hands. The front view shows the lift best. The app tells users to switch sides.
The movement
Keep the right knee bent at 90° and lift it out to the side, away from the body, as if opening a gate. The thigh swings up and out round the hip; the knee and foot rise together, so the shin stays level with the floor and points straight back. The thigh does not drift forwards or backwards. Only the hip moves: the back stays flat, the pelvis stays level and square to the floor, and the weight shifts only slightly onto the left knee and both hands. Stop at about 45° from vertical, hold briefly, then lower the knee back under the hip, hovering just above the mat.
End position
Top: right thigh about 45° out from vertical, knee about 12–15 cm off the floor and 30 cm out to the side, knee still at 90°, pelvis level. At 45° the knee rises about 13 cm and moves about 30 cm out. Lifting the knee to hip height would need 90°, which most people only reach by tipping the pelvis; [2] warns that past the hip's true range the trunk and pelvis take over.
Tempo
1 s up, 1 s hold, 1.5 s down, a brief hover at the bottom without resting the knee.
Form in numbers
What are the angles and distances?
| Measure | Target | Good range | Sources |
|---|---|---|---|
| Hands | under the shoulders, shoulder-width | wrists within 5 cm of the shoulder line | [1] |
| Knees | under the hips, hip-width | within 5 cm | [1] |
| Hip and knee flexion on all fours | 90° | 80–100° | [1] |
| Working knee flexion | 90°, held | 80–100° | [1] |
| Thigh angle out from vertical at the top | 45° | 35–60° | [2] |
| Working hip flexion (thigh forward or back) | 90°, held | 80–100° | [1] |
| Shin at the top | level, pointing back | foot within 5 cm of knee height | [1] |
| Pelvis tilt or rotation | 0° | under 10° | [2] |
| Trunk side shift | none | under 5 cm | [2] |
The targets our 3D demo was built to, from the references below. Bodies differ, so treat the ranges as a guide for your own build.
For coaches
Use this demo in your clients’ programs
The Fire Hydrant is in Trainaq’s exercise library. Add it to a workout, and your client sees this demo in the free Trainaq app above the sets they log.
Sources
