Massive cardio at high levels of intensity will release plenty of endorphins, making creatine supplementation unnecessary. And the effects of this "runner's high" can last up to 23 hours thereafter, allowing for the most intense workouts with the heaviest weights with "minimal" pain during that window
Lifting the heaviest weights w/o pain isn't the issue; it's recovery time. I know tri-athletes, strength/cardio maniacs, and they are sinewy and strong, not bulky (plus ripped). This is the profile of a typical, high end martial artist and yes, they look great but it's a dense type of ripped look. Part of it is due to a type of overtraining where the upper body muscles don't get enough downtime for the bulk to build.
Not true. Cardio is NOT mutually exclusive with muscle building. Cardio can accelerate muscle building. It depends on what you tell your body to do, unwittingly or not:
1) Cardio actually speeds up recovery. With the elevated blood and oxygen circulation during cardio, all of the lactic acid from strength training will be drained out of the system so you won't feel sore. Energy reserves are quickly replenished so that muscle repair and building can quickly begin (if you eat). Cardio is the best "warm down" from strength training you can do. No hot tub necessary.
2) But recovery time will also have a lot to do with your diet. Don't eat for 8 hours after strength training, and you will atrophy. Running will only make it worse.
3) On the other hand, if your triathlete maniac friends are tired of looking like Jet Li, then they need lots of protein and carbohydrates immetiadely following working out. They not only need LOTS of calories to make the protein intake work (protein doesn't work well unless you add at least 4x the carb), but also enough to truly spike your insulin level. I'm talking LOTS of calories, all within 30-45 minutes of post-exercise window. Repeat for a total of 7-8 meals every day.
Unless if they have tape worm, IBS, or Crohn's, every single one of your Jet Li pals WILL get big. Epecially if they train hard and then go sprinting, not just jogging. (The only type of exercise that releases HGH is intense exercise.)
If Jet Li starts getting bigger but losing muscle definition, then he isn't burning enough calories running. Must ncrease intensity, distance, and repetion. If not, then he will end up looking like your meaty couch potato gym rats pals who do no cardio.