Handstand push-ups can really jack your neck and shoulders up, especially when you do them incorrectly. I highlight two things I see regularly in the gym that can damage your spine, neck muscles, and give you headaches.
1. Plunking down onto your head, free-falling and crashing onto your head, slamming your head into the mat...
However you say it, your skull and neck get crunched down and your neck and shoulder muscles seize up to protect your spine.
*What to do instead - slow your descent down to control when and how hard your head touches the ground. It should only lightly tap the floor and you should immediately begin your push - don't sit on your head.
2. Tilting your head back while your head rests on the ground...
Especially during the learning process of kipping, it is common to set your legs up to kip while your head rests on the ground. Letting your head tilt, allowing your forehead to now rest on the ground, puts your head in a compromised position and can give you pain similar to whiplash.
*What to do instead - keep your head in its neutral position and keep most of your bodyweight settled in your arms and hands, NOT on your head and neck.