The title says all, I'm a male, 5% body fat, 18 years smoker that is already struggling to eat enough to earn muscle with minimal fat gain on a clean bulk diet (relying on supplements only when can't fulfill my needs and no junk food) but I also practice martial arts and my cardiovascular system can't keep up to my necessities. I can get out of breath like when you run a lot just by doing legs or abs exercises and doing too much heavy exercises without rest between them.

So which exercises would have the best ratio of calorie spent to improvement on cardio measurements such as VO2 max?

Or in other words, which HIT will be the most "hard" to my heart and lungs with less calories spent?

I'm sure must be any studies, empirical evidence or hard data comparing the results of many HIT training methods, to see which is most effective?

Observations : Ideally I would like to spend at most 20-30 minutes for this 3-4 a week, the less the better.

Goals : My first goal is muscle growth. I'm on a gray area about working on muscle growth and fat control, and at same time improving my cardiovascular system, that's why I'm asking here, its essential to know things like to build a routine that's optimal according to my goals and desires and that is not at odds with others goals. I'll measure how long I can keep my heart rate at 80% and my V02 Max weekly. ( I appreciate any tips on better measurements I could use)

  • Wind sprints would would be my guess. If your body has enough carbs it is not going to break down muscle.
    – paparazzo
    Dec 27, 2015 at 22:16
  • 5
    Cutting out smoking would help too Dec 27, 2015 at 22:52
  • Who said supplements? Good old carbs have been around since the beginning of man and pretty easy to put in 1,800 in a single sitting.
    – paparazzo
    Dec 28, 2015 at 0:46
  • 6
    5% is really low. That's stage-ready for body building, minus the oil.
    – Eric
    Dec 28, 2015 at 3:14
  • 2
    VO2 max is not a great measurement, and the equipment needed to measure it accurately really only exists in laboratory environments. You can improve your VO2 max without improving aerobic capacity simply by losing weight. Also, why would you edit out the smoking information? That's relevant to the what you want to do. Just because you don't like being told to stop?
    – JohnP
    Dec 28, 2015 at 17:02

2 Answers 2


First of all, I highly doubt that you're actually 5% bodyfat. I have above average muscularity and you can see veins all over my body and I'm still not at 5% bodyfat, I am around 8%. Being at 5% is (for the vast majority of people) unhealthy and unsustainable. So if you really are only 5% bodyfat, that probably one of the issues here. Try going up to 8 or 10% to see if that brings positive changes.

That being said, based on your post it sounds like the problem lies not in your cardiovascular system, but in the fact that you smoke and eat too little. You mention that your cardiovascular system can't keep up with your necessities, what do you base that on? How do you know it's your cardiovascular system that is the problem?

I would suggest you try to stop smoking and eat more calories. Do you have any estimate of how many calories you consume on a daily basis? Try adding 300 calories on top of that and see what the result is when you consume that for about a month. If you notice significant positive changes you know you're on the right path, if not, you can make more changes.

  • I’d add that bodybuilders/models/etc are at 5% only right at comp/photoshoot time. While some folks are just naturally lean, it’s uncommon. Oct 7, 2021 at 14:45

So which exercises would have the best ratio of calorie spent to improvement on cardio measurements such as VO2 max?

Skipping, running in general, but skipping is is better

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