The air squat is the base of every squat in CrossFit. Find depth, foot position and tension step by step – no weight, no knee pain, with clear checkpoints.
The air squat is the bodyweight squat where you bring your hip crease below the top of the knee and stand back up tall. It is the first of the nine foundational movements in CrossFit and the base for the front squat, overhead squat, thruster and wall ball.
The honest answer to the question almost everyone asks: yes, deep is fine. A scoping review of the deep squat evaluated 15 studies – 13 to 14 of them (the abstract says 14, the main text 13, about 87 %) found no increased injury risk for the knee [1]. The authors consider the deep squat safe as long as technique stays clean. The caveat belongs here: most interventions lasted only 6 to 10 weeks, and knee pain was often recorded by questionnaire only [1].
Realistically, you learn the basic form in two or three sessions (experience, not study data). It only gets really good over weeks, because mobility does not arrive overnight.
Feet about shoulder-width apart, toes turned out slightly. Your weight sits over mid-foot, not on your toes. Brace your trunk as if expecting a light punch to the stomach.
Milestone: stand still for 10 seconds without wobbling.
Push your hips back as if sitting on a chair behind you. Keep your chest open. This is the moment most people shove their knees forward – let the hips lead.
Milestone: 10 reps to the box without your heels lifting.
Sit down in control onto a knee-high box and stand up without momentum. The box gives you a tangible target and takes away the fear of tipping over.
Milestone: 3×10 clean, knees always tracking toward your toes.
Pick a lower box or drop it. The standard: your hip crease sits below the top of the knee. If heels are the issue, a small lift of 1.5 to 3 cm – about two fingers high – lowered the ankle mobility required in barbell squats in a study of 20 healthy people [2]; for the bodyweight squat this is a transfer, and in practice it makes an upright position easier. Think in an external cue, an image from outside the body: "push the floor apart", not "tense your thigh". This external focus improves execution and retention according to a meta-analysis [3].
Milestone: 3×10 at full depth, chest open, heels down.
Only now do numbers come in: 20, 30, then 50 reps in a row. Breathe in at the top, hold tension briefly at the bottom, drive out as you stand. If a WOD (Workout of the Day) says 100 air squats, you do not need heroism, you need rhythm.
Milestone: 50 unbroken, the last one as clean as the first.
The air squat is one of the least dangerous movements in CrossFit – but repeated often enough it is still a joint stimulus. In an 8-week beginner cohort of 168 participants, 14.9 % were injured; the most common sites were lower back (25 %) and knee (21.4 %) [4]. A systematic review (11 of 12 studies of poor methodological quality) reports from single studies: injured athletes in one shoulder study named wrong technique as the cause in a third of cases, and soldiers with a previous joint injury had a 3.75 times higher injury risk (very wide confidence interval: 0.88 to 18.6) [5]. Treat that as a hint, not as proof.
In practice: stop when the knee hurts at the front or inside (not: burns), and find the cause before raising volume. Increase reps over weeks, not from one day to the next.
This guide explains and motivates but does not replace supervised training. Have your depth filmed from the side or checked by a coach once.
Try the pause squat: go down, count to three at the bottom, then stand. The pause removes momentum and shows you honestly where you wobble. If you can sit stably at the bottom, you will stay calm in sets of 100. And one comfort: in a small study of 32 men (CrossFit novices and competition-experienced athletes), CrossFit experience explained performance in two test WODs best, ahead of VO₂max or anaerobic peak power [6] – so regular short squat sessions get you further than one big effort (experience).
The hip crease must go below the top of the knee. That is the movement standard in CrossFit training and competition. If you reach it with an upright torso and heels down, you have full depth – whatever that is in centimetres.
According to current evidence, no: in one review, 13 to 14 of 15 studies found no increased injury risk, though most studies ran only a few weeks [1]. Clean technique and gradual load build-up matter, not avoiding depth.
Usually ankle mobility is lacking. A lift of 1.5 to 3 cm under the heels lowered the required ankle mobility in a study of barbell squats [2]. Train mobility in parallel so you can drop the aid later.
Two to three short sessions per week of 3×10 to 3×20 clean reps are enough at the start (experience). What matters is that your form holds up to the last rep.
No. Flat, stable shoes are enough. A small heel lift is a bridge while mobility is missing – but it does not replace training the ankle.
Rowing on the Ergometer: Legs, Trunk, Arms – In That Order