Then I started thinking to myself, "hmm, maybe I better check this out just to make sure I am 100% right."
In my search of the recent literature, I came across an article published in January 2011 out of the Journal of Medicine & Science in Sports & Exercise .
This article proved exactly what I expected: sprint intervals (the awesome and fun workouts my group does), with a much lower time commitment, induced identical performance and physiological improvements compared to longer bouts of endurance training (long boring runs that regular people do not always have time for).
Study Design:
This is a breakdown of how the study was completed. 20 healthy subjects were divided into 2 groups. Both groups would undergo 3 training sessions per week for 6 consecutive weeks. This is what each group did:
- Group 1: Endurance Training:
- 30 minute runs (for first 2 weeks), 45 minute runs (weeks 3 and 4), and 60 minute runs (weeks 5 and 6). All runs were done at 65% of their maximal effort.
- Group 2: Sprint Interval Group:
- 30 second maximal effort bouts with 4 minutes active recovery. They would complete 4 sets in weeks 1 and 2 and up to 6 sets in weeks 5 and 6.
Results:
The improvements seen in both groups were measured in a number of ways (ranging from body fat percentage to 2000m Time Trial time). Despite the sprint interval group spending less than half the amount of time running compared to the endurance group by the final weeks of the program, they still showed equivalent levels of improvement:
- 2000m Time Trial:
- Both the endurance group and the sprint group showed about a 30s improvement throughout the 6 week program. I was especially excited about this parameter because a ~2km TT is how we measure progress in the Runners' Choice group!
- VO2 max:
- This is the measure of the maximum amount of oxygen your body can consume per unit of time per kg of body weight. Again, both groups showed similar levels of improvement (about 12% with each).
- Body Composition:
- This one is interesting! Both groups gained about 1.0% lean mass (muscle), which again is a positive sign for both groups. However, the interval group lost 12.4% body fat, while the endurance group lost only 5.8% body fat. While there is no significant difference in this study, these results are consistent with other studies on interval training. Bottom line: you lose more fat in less time with intervals!
- Cardiac Output:
- This is the measure of how much blood your heart can pump throughout your body. Interestingly, the endurance group showed a 9.5% increase, while the interval group showed none. This shows that while interval training is extremely useful, it cannot 100% replace all forms of training.
As you can see, interval training is an absolutely crucial component of training. In approximately half of the total training time you can achieve:
- The same improvements in your race times
- The same improvements in your VO2 max
- The same increases in lean body mass
- Higher levels of fat loss
A Few Additional Thoughts (after the fact):
Also, keep in mind that while you cannot replace long runs with intervals, by the same token you cannot eliminate the need for intervals with long runs. Other parameters such as how your body produces and manages lactic acid were not measured in this study- something that interval training will have a more significant impact on compared to endurance runs.
At the end of the day, best case scenario, doing both is ideal. However, if you are limited by time, go with the interval workout.
Reference:
Click here for the article
