Climbing Notes
Resting positions

Arm position on a rest: up, at heart height, hanging, shaking

Where you put your resting arm changes how fast oxygen comes back. Raised above the heart it refills much more slowly. Hanging low and shaken loosely beside the body is the best-supported option.

5 min read 5 sections 1 interactive

In plain words

Blood has weight. With your arm above your heart, your heart has to push blood uphill to reach the forearm, so less pressure is left to push it through the muscle. With your arm hanging low, gravity adds pressure to the arteries, but it also fills the veins, so on its own hanging low gains you little over heart height. Shaking helps here: moving the hand and forearm squeezes blood out of the veins, making room for fresh blood. The result: resting with your arm overhead is slow, at heart height is fine, and hanging low while shaking loosely is the best of the options that have been tested.

Memory hook

Below the heart, loose, and shaking.

How gravity and shaking change the refill

See it

Pick a position for the resting arm and turn shaking on or off. The gauges show the pressures at the forearm in this simple model. Under them are the measured comparisons.

Why "up" hurts more than "down" helps

Arm up

Every 10 cm above the heart takes about 8 mmHg off the pressure in the forearm's arteries. The veins can't drop below zero to make up for it, so the push through the muscle falls.

Arm at heart height

Gravity neither helps nor hurts. Most lab tests of half-times use this position.

Arm hanging low, still

Gravity adds about the same pressure to arteries and veins, so the push is about the same as at heart height. One study found no difference in blood flow between heart height and 27.5 cm below.

Arm hanging low, shaking

Moving the forearm squeezes the veins empty (the muscle pump), so more of the arterial pressure is used to push blood through. Shaking beside the body re-oxygenated the forearm 32 % faster than keeping the hand over the hold.

The holding arm has the same problem

On most rests the holding hand is above your head, so its forearm refills slowly, on top of having to grip. That's one more reason to swap hands every few seconds. It's also why a rest where you can hold low, with an undercling at chest height or a side pull at shoulder height, can recover both arms better (coaching practice).

How to shake

Let the arm hang straight down

beside the body, shoulder relaxed.

Shake loosely

from the wrist and forearm, like shaking water off your hand. Stiff shaking keeps the forearm muscles working.

Swap every few seconds

so the holding arm gets its turn.

Breathe out slowly

to help the grip relax.

The evidence

Numbers from adults only.

  • Measured With the arm raised overhead (180° shoulder flexion), the half-time of forearm oxygen recovery after a cuff test was 2.44 times longer and the recovery rate about 61 % lower than lying with the arm at heart level. People varied a lot in how much elevation affected them. Climbing ability and arm dominance made no difference. Štěpánová et al. 2026: 51 adult men (20 advanced to higher elite, 21 intermediate, 10 non-climbers). BMC Sports Sci Med Rehabil, 2026.
  • Measured With the forearm 27.5 cm above heart level, peak forearm blood flow during a light grip (15 % of maximum) was 11.1 vs 15.6 ml/min/100 ml at heart level, and the grip could be held about 66 s less (390 vs 456 s). At 27.5 cm below heart level, flow was 14.2, and the study didn't report it as different from heart level. At grips of 20–70 % of maximum, hold times were unaffected by position. Heinzl et al. 2025: 14 healthy young men. Sci Rep 15:1250.
  • Measured Shaking the forearm beside the body gave 32 % faster re-oxygenation and 22 % longer repeated-grip time than resting the hand over the hold. Baláš et al. 2016: 22 adult rock climbers. Eur J Sport Sci 16(7):764–772. Arm position and shaking changed together in this study, so their separate effects aren't known.
  • Model Blood pressure changes by about 0.78 mmHg per cm of height (blood's density × gravity). The model uses 95 mmHg arterial and 5 mmHg venous pressure at heart height, and an illustrative 25 mmHg drop in venous pressure from shaking. It is a teaching model, not a measurement.
  • Coaching practice Loose shaking, swapping every few seconds and choosing low rest holds are common advice.

Model assumptions

  • Positions: hand 50 cm above the heart (up by the hold), at heart height, and 55 cm below (hanging).
  • Arterial pressure at the forearm = 95 mmHg + 0.78 × cm below the heart (minus when above). Venous pressure = 5 mmHg + the same change, but never below zero, because veins collapse rather than pull blood.
  • Shaking lowers venous pressure by 25 mmHg when the veins are full (hanging low) and by almost nothing when they're already empty (arm up). The 25 mmHg is an illustrative number.
  • "Pressure pushing blood through" is arterial minus venous pressure. Real blood flow also depends on vessel widening, grip tension and individual differences, which this model leaves out.

Try it

Drill

Rest-hold refill: switch and shake low.

Next read

Half-times explained. Turn on Resting arm overhead there.

Related

Shaking: arm position and rhythm.

Common mistakes

Shaking with the hand up by the hold

raised, the forearm refills much more slowly.

Hanging the arm low but holding it stiff

shake loosely so the veins empty.

Resting one arm for a long time

the holding arm, usually overhead, is losing out the whole time.

Assuming lower is always better

in one study, 27.5 cm below the heart wasn't measurably better than heart height. In the model, shaking is what makes hanging low pay off.