From what I can gather from reading here on the forum - it varies from company to company - but it is separate from the DOT physical. From what I can gather it involves lifting a crate (I've read the weights from 20-78#) from floor to waist height a couple times. Then the crate to head height (not sure of the weight there). Also walking a distance with said crate. Also being able to 'squat walk' like you would have to do under the trailer without knocking yourself on the head - all the while making sure your pulse and BP stay within a 'normal' (non dangerous) range. Needless to say - I've been working on my upper body strength just in case!!