Controlled breathing, as mentioned, is central to the wim hof method, the yogic practice of pranayama, and to many kinds of martial arts and meditation, and doesn't really have the potential for injury (with the exclusion of the more physically demanding martial arts). Some of those practices are also more accessible to people with mobility issues.
My personal experience with yoga and meditation, is a very significant uplift in mood, and better sleep (I used to have a very bad snoring problem). I also do a mix of weighted exercise, callisthenics, and cardio, and I've found the combination to work very well.
6 days a week of HIIT training, without enough time for your body to recover is a recipe for injury. Of course, this can vary from person to person and the intensity of the workout and the level of your experience and form - but these are things you didn't mention.
This would of course lead to injury. I don’t think anyone wants to squat heavy after sprinting.
Weightlifting is pretty safe when done right. Just make sure you have plenty of rest. At the same time, unrelated, but the posture benefits are way overrated. In fact, it’s gonna lead to bad posture over time unless you couple it with yoga or some sort of corrective stretching.
That's a fair call. Heavy weight training was usually on separate days, but I recall some crossfit WODs would include deadlifts alongside other fast-paced exercises, and now I question the safety of that. Those deadlifts were likely low weight, high-rep though.
Bodyweight training/calisthenics is interesting but is lacking on two of the best exercises for posture: Face pulls and (Romanian) Deadlifts. For Deadlifts light to moderate weight is enough, with perfect form, be careful if you have tight hamstring to work on mobility.
Bodyweight stuff is what I mostly do now with some weighted exercises, but I'm keen to get into heavier weights again.
The technique I learnt was at a 10-day silent retreat, of which we spent the first days (9-hours a day) exclusively on concentrating on respiration. With this new awareness, I realised, just in my day to day, and especially when I'm trying to focus, I sometimes forget to breathe. This is something I otherwise would not have noticed and not corrected. Also important to note that I used to have mild sleep apnoea, and I would always wake up feeling groggy from lack of oxygen. I haven't had a sleep study since I've started practicing, but I no longer wake up groggy, and now I can go to sleep within the hour instead of tossing and turning half the night.
I've noticed that yoga and meditation have also improved my breathing and form during exercise.
I actually find controlled breathing is very good for regulating pain.
The breathing also helps mentally but also helps relax the body. As you are exerting yourself it can be a natural response to carry tension in your body. Tension is usually the enemy of body mechanics - it leads to inefficient technique.
Watch any sport (including running) and something notable about any pro is how easy or relaxed they look.
This can be learned and breathing has some chicken/egg relationship with relaxation
Meaning, one a bit learns to control the breath, without thinking about it, just doing?