Give back blows between the shoulder blades, on the flat midline of the upper back, with the heel of one hand. Aim for the center of the back at roughly the level of the shoulder blades, not the neck, not the lower back. Deliver each blow firmly enough to create a sharp, directed force that drives trapped air out of the lungs.
That single sentence covers the practical answer most people need. The mechanism behind it is where the real science sits, and the details explain why the instructions specify that exact location instead of "somewhere on the back."
Force transfer and the pulmonary pressure spike
A back blow works by compressing the chest cavity through the posterior wall, generating a sudden spike in intrathoracic pressure. The airway is a tube with a foreign body lodged in it. To move that object, you need a pressure gradient strong enough to overcome the friction and the seal around the object.
The upper back between the scapulae sits directly behind the thoracic spine and the posterior lung fields. Force applied there travels through a relatively thin layer of muscle and rib into the chest cavity. Force applied over the shoulder blades themselves or lower down gets distributed across a wider, more curved surface. That distribution wastes energy.
Think of it this way. A blow over the flat midline acts like a piston on a closed cylinder. A blow over a curved edge acts like hitting the side of a barrel, the energy spreads sideways instead of compressing the contents. The midline upper back gives the most direct line to the airway and the largest achievable pressure transient.
The blow must also be sharp rather than a push. A slow, heavy push compresses the chest but allows air to leak around the obstruction. A rapid blow produces a brief, high-amplitude pressure wave, and that transient peak is what dislodges a partially or fully obstructing object.
Numbers that calibrate location and force
Choking kills. The CDC has recorded thousands of choking deaths annually in the United States, and food is the leading cause. The practical implication is that the difference between an effective blow and a wasted one can be measured in seconds, not minutes.
Location tolerances are tighter than most people assume. The shoulder blades in an average adult span roughly the region from the level of the T2 vertebra down to about T7. The upper half of that band, centered near the T3–T5 level, is the target zone. A blow placed near the base of the neck risks pushing the head forward without compressing the chest. A blow placed at the mid-to-lower back lands below the main lung fields and dissipates.
Force matters as much as placement. Adult back blows are delivered with enough force to move the torso slightly, not a pat and not a strike intended to hurt. The heel of the hand is used because it concentrates force into a small, flat contact patch, which raises local pressure compared with an open palm.
The standard sequence also fixes the number. Most choking protocols direct a cycle of up to five back blows, followed by up to five abdominal thrusts (or chest thrusts for certain groups), repeated until the object clears or the person collapses. The "up to five" wording is deliberate. You stop the moment the object comes out.
When the standard location does not apply
Infants are the largest exception. For a choking infant under about one year, the recommended position is face-down along your forearm with the head lower than the chest, and the blows land between the shoulder blades, but the force is calibrated far lower than for an adult. The smaller chest and more fragile ribs change both the safe force and the effective compression.
Pregnancy and obesity shift the calculus on the thrust phase more than the blow phase. The back blow location stays midline upper back. The abdominal thrust that follows is often replaced with chest thrusts because abdominal compression is unsafe or ineffective. The back blow is still the opening move.
A person who is coughing forcefully is not yet a choking victim in the protocol sense. If they can cough, speak, or breathe, you encourage coughing and do not start blows. Back blows begin when the cough becomes silent or ineffective, or when the person cannot breathe, speak, or make a sound.
Wheelchair users and people seated upright can still receive back blows, but positioning matters. Lean the person forward if possible so the head drops below the chest, which aligns gravity with the blow. If they cannot be leaned, deliver blows to the same midline upper-back zone with the person as upright as the situation allows.
Here are the situations that should stop you or redirect you:
The person is coughing effectively or can speak: do not strike, encourage coughing instead. The person is an infant under one year: use the infant position and infant force, not adult blows. The person is unconscious or has collapsed: stop back blows and begin CPR protocols. The object is visible in the mouth: do not blind-sweep with a finger, which can push it deeper. The person is pregnant or has a large abdomen: keep the back blow, plan for chest thrusts next. The person has a suspected spinal injury: minimize torso movement and get emergency help fast.
Common mistakes about the strike zone
The most frequent error is aiming too high. People instinctively strike the neck or the top of the shoulders because that is where they perceive the blockage to be. The airway obstruction sits lower, and a neck strike risks injury without compressing the chest.
The second error is aiming too low or too wide. Blows that land over the lower ribs or the sides of the back compress the abdomen or the flanks. That can cause injury and produces a weaker pressure transient in the chest.
The third error is using an open hand or a gentle tap. A soft blow may move the person without generating the pressure spike needed to eject the object. The heel of the hand, firm contact, and a sharp delivery are all part of the mechanism, not stylistic preferences.
The counterintuitive detail is this: hitting harder is not always better. Above a certain force, the ribs absorb and distribute the energy, and the chest wall deforms rather than transmitting a clean pressure wave. The goal is a sharp, well-placed transient, not maximum violence. Professionals calibrate to "enough to move the object," and that is usually less than a layperson's panicked maximum.
Back blows versus the alternatives
Back blows are rarely used alone in adult protocols. They are the first step in a sequence, and the comparison below shows where they fit relative to the other maneuvers.
| Maneuver | Where force is applied | Best for | Main limitation | Typical sequence role |
|---|---|---|---|---|
| Back blows | Midline upper back between shoulder blades | Opening move for most ages | Needs correct placement and lean-forward position | First, up to 5 |
| Abdominal thrusts | Just above the navel, below the breastbone | Conscious adults and children over 1 | Unsafe in pregnancy and obesity | After back blows, up to 5 |
| Chest thrusts | Center of the breastbone | Infants, pregnancy, obesity | Less familiar to lay rescuers | Alternative to abdominal thrusts |
| Infant back blows | Between shoulder blades, face-down | Infants under 1 | Requires correct forearm position | First, up to 5, alternating with chest thrusts |
| Blind finger sweep | Mouth | Visible object only | Can push object deeper | Not recommended for blind sweeping |
| Cough encouragement | None | Effective cough present | Only works if airway partly open | Before any blows |
The table makes one thing clear. Back blows are not a standalone rescue. They are the front end of a cycle, and their effectiveness depends on being followed by the right next maneuver.
Timing the response
Choking is a seconds-to-minutes emergency. The timeline below shows how the response unfolds and where back blows sit in the clock.
| Time from onset | What is happening | Correct action |
|---|---|---|
| 0–10 seconds | Person clutches throat, cannot speak | Confirm choking, ask if they can cough |
| 10–30 seconds | Cough becomes silent or ineffective | Begin up to 5 back blows |
| 30–60 seconds | Object not cleared | Follow with up to 5 abdominal or chest thrusts |
| 1–2 minutes | Cycle repeats | Alternate blows and thrusts until cleared |
| 2–4 minutes | Person weakens or collapses | Lower to ground, begin CPR, call emergency services |
| 4+ minutes | Oxygen deprivation advances | CPR continues, emergency services en route |
The clock is the argument for getting the location right the first time. Each wasted blow costs seconds you do not have.
Practical steps and thresholds
The action sequence is short, and the thresholds are concrete:
Confirm the person cannot breathe, speak, or cough effectively. If they can cough, encourage coughing and do not strike. Lean the person forward so the head drops below the chest, supporting them if needed. Strike with the heel of one hand, midline between the shoulder blades, up to five times, sharply and firmly. If the object does not clear, move to up to five abdominal thrusts, or chest thrusts for pregnancy, obesity, or infants. Alternate the cycles, checking the mouth between rounds for a now-visible object. Call emergency services immediately if the person collapses or the object does not clear within the first cycle or two.
The reconciliation point across sources is the number five. Different protocols phrase it as "up to five" or "five and five," but they agree on the structure: a bounded set of blows, then a bounded set of thrusts, repeated. The bound exists so rescuers reassess rather than hammering indefinitely.
One professional caveat deserves emphasis. These instructions are for lay rescuers responding to a witnessed choking emergency. They are not a substitute for a certified first aid or CPR course, where force calibration and positioning are practiced on manikins. Reading the location is not the same as delivering it correctly under stress.
This article is general educational information about choking first aid, not a diagnosis, treatment plan, or substitute for certified training. It does not promise any outcome, and individual circumstances vary. For hands-on instruction, take a course from a qualified local first aid or CPR provider, and for any choking emergency, call your local emergency services immediately.