Why You’re Wasting Your Time Doing Only Long, Slow Aerobic Workouts

In many of the programs that I write out for my clients who are pursuing fat loss, I include a weekly or bi-weekly “long slow fat burning session”. This is chance for an individual to train their body how to oxidize and utilize fat efficiently during exercise, and is a good opportunity to still burn calories and burn fat, without breaking down the body in the same way as a hard session would.

After all, if you go hard all the time, every day, you’re just going to get hurt or burn yourself out.

But some people, and especially longer distance endurance athletes such as triathletes, get stuck in a rut, performing a long slow fat burning session for nearly every workout – completely avoiding intensity or just not doing intense workouts or intervals because it takes them outside their comfort zone.

There are even trainers, athletes and coaches who would argue that long slow distance training is the ultimate way to get fit, since it turns the body into an aerobic machine and allows for superior development of the “slow-twitch” muscle fibers, which take a longer time to fatigue and primarily utilize fat as a fuel.

But this really isn’t true. As a matter of fact, you’re wasting your time and getting subpar results if all you’re doing are long, slow aerobic workouts.

It’s a myth that LSD is the best way to train. And this holds true for everyone from the 50 year old woman trying to shed a few pounds of fat to the triathlete attempting to qualify for the Ironman World Championships in Kona.

Data from animals provides some insight into this issue. In a study published in the Journal of Applied Physiology in 1982, researches Dudley, Abraham and Terjung observed that peak oxidative capacity of muscle fibers occurred when training sessions were performed at 94% of VO2 max intensity, which is far more difficult than the “long slow fat burning” zone.

To really get you fit FOR ENDURANCE OR FOR FAT BURNING, try the following workout, which was suggested by Stephen McGregor at the 2010 USAT Art & Science of Triathlon Coaching Symposium and is based on a 1998 study in the Journal of Applied Physiology, which noted that 30 second efforts led to incredibly significant increases in power output, peak power and VO2 (VO2 is your maximum oxygen consumption during exercise, and the “gold standard” measurement of performance potential in something like triathlon).

You’d probably expect the increases in power and VO2 mentioned above, but the interesting part is that the study also found significant increases in the oxidative process of mitochondrial enzymes, which basically means that the body’s cells became more highly equipped for efficiency during aerobic activity – the type of activity you need during a triathlon, or for burning fat.

30 second all out “sprints”
• Start @ 4 x 30 sec all out w/2-4 min rest (3 x week)
• Increase to 10 x 30 sec all out w/2.5 min (3 x week)
• Do for 7 weeks (6.5-15 min/week)

Some people will also argue that hard exercise doesn’t increase capillary density in the same was as long slow distance workouts, which means that the body wouldn’t actually be able to feed sugar and oxygen to muscles quite as well if somebody were doing “interval” style training instead of low intensity, steady-state aerobic training.

But data suggests this isn’t true either. A study in the Journal of Physiology in 1977 showed that high intensity training, around 80% VO2 max, increases capillary density to a greater extent than low intensity training. In this study, participants did the hard efforts 40 minutes per day, 4x/week for 8 weeks.

Another study in the Journal of Physiology in 2004 found that high intensity training increased capillary density by 20%! Both studies suggest that high intensity exercise is significantly effective at increasing both capillary density and capillary growth factor release (growth factor being another highly important fitness training response).

Obviously, some of these studies are old and some of them were done on animals, but the take away message is this:

Don’t let anyone convince you that long, slow aerobic training is the best way to get fit, even for something like a triathlon. Sure, it should certainly be ONE component, but high intensity interval training will get you more bang for your buck, especially if you’re pressed for time.

I’d love to hear your comments. Do you agree? Disagree?  I’m especially interested if any of you are going to begin incorporating the “7 weeks of 30 second intervals” workout suggested above. If so, keep me posted below on your progress!