As a "formerly advanced" climber who is trying to get back into a healthy regimen after a year or two off, this book was excellent review of some obvious components of active practice that I'd forgotten in my rush to get back to my old level of climbing. Horst continues to be the best when it comes to training guides. Cannot recommend this book (or any of the others) enough.
1) The biggest critique I have is that transitions from poses are too aggressive and, in many cases, FAR too quick. This could very easily result in stabilizer injury with those healing from core, back, spine or neck injuries or those who don't have the best core strength to begin with. The example that comes to mind is in the 'Sweat" workout. The rapid change from low lunge into a one-foot balanced runner caused an injury for me the first week, and just again today after 6 weeks. If you have ANY history of car crash with spinal involvement, low back problems, abdominal surgery, or core weakness, you MUST listen to your body carefully during these workouts. The modifications are helpful, but they simply decrease the impact of the position once you are in them. The quick transitions in PiYO keep heart rates up, but they also jeopardize the safety of joints or muscles that are a) fatigued from participating and b) unstable due to weakness. Adapt and SLOW DOWN when needed. Better to do 2 sets safely than 4 sets and getting hurt.
Thus, little is known about the effects of monitored vigorous exercise in elderly people. While significant benefits for basic motor tasks (such as balance and gait) can be achieved through different kinds of physical activity (i.e., stretching exercises, treadmill, Pilates, and strength and balance training), no conclusive relationship has been proven between its intensity and such improvements. Recently, Pau et al.  reported that spatiotemporal gait parameters and sit-to-stand performance significantly improve through vigorous (but not light) exercises, thus suggesting that higher levels of intensity might be more suitable in generally improving static and dynamic daily motor tasks.