Q: Should I put my hands on hips, knees or head to recover faster?
(He added: wouldn't hands on your head open the lungs up the most?)
A: Physiologically, it's best to bend over and chuck your hands on your knees.
I like how Brian Mackenzie has answered this question in the past... Gravity is a real thing. We might not fully understand it, but if you minimise the muscle energy required to maintain posture (and fight against gravity), you're able to recover much faster.
It's also been shown in a 2019 study by Michaelson and others. They assessed recovery times and heart rate in two groups. One recovered with their hands on knees, the other recovered with their hands on heads. The "hands on knees" group showed a significantly faster rate of recovery. Their heart rate dropped 53bpm in one minute compared to only 31bpm for the "hands on heads" group.
It's also natural. What do we do when we're gassed? We have a tendency to bend over and peg ourselves up with our hands on our knees.
It might not be the best body language on the field. Competitors might look at it as a sign of weakness or fatigue. But in terms of training, it'll help you recover faster and push harder for longer.