A growing body of fitness research is finding that workout intensity has more impact on health and weight loss than does workout duration. Interval workouts that mix fast-paced workout segments with moderate segments are yielding faster and better weight loss versus longer moderate duration workouts.
The higher-intensity workouts help you expend more total calories per minute while improving your aerobic capacity. The longer, moderately intense workouts, however, will build your exercise endurance, help maintain your cardiovascular fitness, and help your body recover from the higher-intensity workouts.
Studies have shown that long endurance activities, such as aerobics, can cause muscle catabolism (the breakdown of muscle tissue), while High Intensity Interval Training (HIIT), on the other hand, allows you to metabolize the fat without losing muscle. Take a look at long distance runners -vs- sprinters, for instance. Long distance endurance runners tend to have less muscle mass than sprinters. The short maximal energy bursts of sprinters release testosterone and growth hormones in greater amounts. These hormones are anabolic in nature, which means they build muscle. On the other hand, running for long durations releases cortisol, a catabolic hormone, which breaks the body down and can be potentially bad for the body.
HIIT has been shown to greatly improve athletic performance while maintaining/gaining muscle. For already well-trained athletes, improvements in performance can become difficult to attain, and increases in training volume can potentially yield no improvements; therefore, research would suggest that improvement in endurance performance can be achieved through high-intensity interval training.
It has also been recently shown that two weeks of HIIT can substantially improve insulin action in young healthy men; therefore, it may represent a viable method for prevention of type-2 diabetes.
If you are just starting an exercise routine, you should start by working on increasing duration (time spent in each workout) and frequency (number of workout sessions per week) first, before starting a more rigorous interval training program. And remember; always consult your doctor before starting any exercise program.
Feel free to contact me if you have any questions.
I am an Independent Fitness Coach with a passion for fitness and rock climbing. I started climbing in 2004, and have become totally adicted. In 2008, I started on P90X and became a coach. This blog is to share my journey and musings in fitness, climbing, and nutrition.
The President's Challenge is a program that encourages all Americans to make being active part of their everyday lives. No matter what your activity and fitness level, the President's Challenge can help motivate you to improve.