There's a big common myth that makes a lot of lazy people happy, but hinders their full potential; cardio makes you lose size. The myth isn't completely wrong, certain types of cardio can make you burn through muscle for fuel. Funny enough it's the same type of cardio that many people do when they're trying to drop body fat, like as if muscle size doesn't matter anymore - ironic, right?
High intensity training, in particular high intensity interval training (HIIT), involves performing repeated short bursts of high intensity exercise followed by sufficient rest. Nothing fancy either. The more simple and basic the exercise, the better. High skill exercises that require a lot of coordination and precision reduces your intensity capability, so exercises such as sprints, cycling, rowing, and basic weight lifting exercises are best. A key factor to keep in mind is these exercises need to be performed with 100% effort and intensity; no 'fast' jogging - it has to be an all-out sprint that barely allows you to breathe. This is crucial in inducing the desirable hormonal and metabolic effects that will help to tear through body fat and build muscle!
So how does it all work? Why is high intensity training better for muscle gain, preventing muscle loss, and cutting through body fat than just jogging? 'Why does my stationary bike and treadmill tell me I burn more calories cycling for an hour as opposed to doing interval sprints for 20 minutes'? Do me a favour, just rip that big screen off - it's lying to you and isn't telling you the whole story. Let's get a little deeper into how our bodies work.
The Science Behind It
When you perform any form of exercise, your body predominately relies on specific energy sources, in the following order:
- ATP (explosive, high power energy) - shorter than 30 sec
- Glucose (high power, fast generating) - 30 sec to 45 mins
- Amino acids (from skeletal muscles) - dependant on glucose availability
- Fatty acids (from fat cells) - after 30-45 mins
Burning fat stores is the last thing your body wants to do; it's there to keep you alive when you don't catch a rabbit or find a berry bush for days on end. Consequently in an attempt to survive, it will start burning through everything else before it has to use too much of its fat stores, including burning through your muscle cells! Obviously not great for trying to keep or build them. However high intensity training doesn't reach this phase; it predominately only burns ATP and glucose, leaving your muscles intact. But there's more. The powerful muscular contractions of high intensity training also causes multiple desirable effects, including:
- Increased testosterone production
- The translocation of GLUT-4, which allows glucose to enter skeletal muscle cells without the requirement of insulin
- Increased human growth hormone (HGH) production
- Micro muscle fibre tears
- Increased protein synthesis
- Increased lactic acid threshold
- Increased blood capaliaries
- Increased aerobic and anaerobic performance
- Potential to build more muscle mass
As well as not increasing your resting metabolic rate anywhere near as much as high intensity training, steady-state cardio in-fact causes your body to become more efficient after a period of time by slowing its resting metabolic rate to conserve energy. This is bad news for getting shredded, as it consequently prevents you from dropping more body fat for the same caloric intake, thus leaving you with only two options:
- Increase your exercise frequency and/or time, or
- Reduce your calories even more
Therefore although cardio isn't necessary when in a 'bulking' phase, it doesn't mean you can't do it - just be smart and do high intensity training. Not only will you keep your cardiovascular system in top shape, you'll also help prime your body to grow more muscle, stay lean, and improve your resistance training performance!