Are intervals more beneficial to distance runners than other workouts, such as steady state runs or tempos?
(Intervals consist of short bursts of high intensity runs separated by a recovery period of slow jogs. Tempos are run at a “comfortably hard” pace, about 85% of max heart rate or an 8 out of 10 on the perceived exertion scale. Steady state runs are run slightly slower than tempo runs).
An article written by Alex Hutchinson in the March/April issue of Canadian Running reported on a recent Danish study that attempted to answer this question.
The study consisted of two groups that ran three times weekly. The interval group ran 5 x 2 minute sprints (5 repeats of 2 minute sprints) at 95% max heart rate. The second group completed hour long steady state runs at 80% max. After 12 weeks, the group running intervals had increased aerobic fitness by 14%, whereas the steady state group increased theirs by 7%.
The steady state group’s workouts were one hour in duration. The interval group ran for only 10 minutes per workout! Including a 2 - 3 minute recovery period between intervals, this group’s workouts lasted just one-third to one-half as long as the steady state group’s exertions. Twice the improvement in less than half the time! Very compelling indeed!
The results of the Danish study coincide with those of a 2007 Norwegian study, as reported in the April 2007 issue of Running Research News. During this 8 week study, runners whose training included intervals ranging from 15 seconds to 4 minutes in duration achieved significant improvements in maximal aerobic fitness (as measured by VO2max). The groups running tempo and LSD (Long Slow Distance) runs did not experience an appreciable aerobic improvement.
At the end of the Norwegian study, both the groups running intervals and tempo workouts experienced similar increases in lactate threshold speed (the running intensity where lactate begins to rapidly accumulate in the bloodstream), an important and reliable indicator of running performance.
Both studies concluded that interval workouts yield greater improvements in aerobic fitness/capacity than tempo or steady state workouts. Clearly, improving your aerobic capacity (your ability to utilize oxygen) is a key factor in improving your running and racing.
Should we then scrap tempo runs and steady state runs, replacing them with interval workouts? If you’ll pardon the pun, not so fast! The steady state group in the Danish study experienced a greater reduction in resting heart rate, body fat and cholesterol than the group running intervals, thereby conferring significant benefits to overall health.
In addition, longer steady state and tempo runs impart an important psychological benefit. They increase your mental ability to withstand faster running for extended periods of time – very critical come race day.
Different workouts have different purposes, providing different physiological and psychological benefits. To quote Hutchinson: “High-intensity intervals are a great, time-efficient workout, but they work best as part of a balanced program.”
Interested in a well-balanced personalized training program that will help you run your personal best? Click on Achieve Your Running Potential for details.
Bennett Cohen (the Savvy Runner) and Gail Gould are the Founders and Presidents of the International Association of Women Runners (IAWR). To learn more about this global community of women who share a passion for running, visit www.iawr-connect.com.