It’s that time of year when athletes have gained a couple of excess pounds of flab and are starting to think about taking it off. The traditional method for doing this is by doing lots of long, slow miles. The slower you go, the better, according to this age-old way of exercising to reduce body weight. Zone 1 is perfect, right? But is that the most effective way?
In a classic study (Tremblay 1994) on this topic researchers at Laval University in Quebec, Canada had one group of subjects exercise at a low intensity (low heart rate zone 1) for 20 weeks. Another group did high-intensity intervals (15-90-second sprints at 60-70% of max power) for 15 weeks. The low-intensity group burned 28,757 Calories while the high-intensity group burned 13,829.
Guess what happened. The high-intensity group had much greater reductions in skin-fold measurements when expressed in relation to energy expended. This was the result of increased fat metabolism during periods of rest between training sessions. The high-intensity group also had significant increases in the enzymes that burn fat for fuel. The low-intensity group had no changes in these enzymes.
Note that the intensity of these two groups was extremely different. Low heart rate zone 1 is so easy you’d wonder if you were doing anything of value for your fitness. The high intensity was very high. It would be a mental challenge to do this workout several times a week for 15 weeks.
Realize that I’m not suggesting how you should train at this time of year. There’s a big difference between exercising for fat loss and for race performance. I typically see any extra weight my athletes have gained over the holidays gradually come off in the following weeks as training intensity increases gradually without going to extremes in training.