1 addition.

Only all-out training recruits the fast twitch muscle fibers. These are the fibers that that give you strength.

Intermediate exercises or endurance only turn on the slow twitch fibers, which make up 50% of the muscle.

Example of all-out training:

3 - 7 30 sec sprints (can be running, spinning, ergotrainer) with 4 minutes rest in between. And allow 2 days recovery between training sessions.

Very time efficient, recruits all the fibers, limits ROS damage, releases GH, is fun, and gives more stamina than endurance. Works on improved insulin action, improved lipoprotein lipase activity, and greater clearance of plasma triglycerides.

Important : make variations in training all the time. The body is an adaptive dynamic system. The last thing we want is dull regular repetitive stuff. Have fun, play, sprint and rest; lots of rest!