Four Lessons I Have Learned From Physiology
And how they can make you a faster runner
By Jason R. Karp, Ph.D.
As featured in the June 2008 issue of Running Times Magazine
One of the things I love most about the sport of distance running is that, in spite of its simplicity of putting one foot in front of the other, it is also extremely complex. When done correctly, it is a scientific endeavor to maximize one's speed and endurance. Unfortunately, nearly all scientists spend their careers in academia without venturing out into the arena that got many of them interested in physiology in the first place -- competitive sport. As a result, few scientists are coaches. The opposite is also true -- few coaches are scientists. Being both, I have learned that each can learn from the other, as my experience has given me a unique view of the sport and of the training process. Here are four lessons I have learned from physiology and how they can make you a faster runner.
Physiology lesson 1.0
Lactate threshold and running economy are more important than VO2 max.
What It Means For You: Threshold training (tempo runs), high mileage, and power workouts are more important than long intervals, especially once your VO2 max has plateaued.
While VO2 max (the maximum volume of oxygen your muscles can consume per minute) has received most of the attention among runners and coaches, a high VO2 max alone is not enough to attain elite-level performances; it simply gains one access into the club, since a runner cannot attain a high level of performance without a high VO2 max. But, while you can improve your VO2 max, it is largely genetically determined. The other two major physiological players of distance running performance -- lactate threshold (LT) and running economy (RE) -- exert a greater influence on your performance and are more responsive to training. I have tested many athletes with an elite-level VO2 max in the laboratory but few of them were capable of running at the elite or even sub-elite level because they did not have a high LT or were not very economical.
From the time of the classic study published in Medicine and Science in Sports and Exercise in 1979 by some of the most prominent names in exercise physiology (Farrell, Wilmore, Coyle, Billing, and Costill), research has shown that the LT is the best physiological predictor of distance running performance. This threshold demarcates the transition between running that is almost purely aerobic and running that includes significant oxygen-independent (anaerobic) metabolism. It represents the fastest speed you can sustain aerobically. (All running speeds have an anaerobic component, although at speeds slower than the LT, that contribution is negligible.) Since the LT represents your fastest sustainable pace, the longer the race, the more important your LT.
Running Economy (RE) is the volume of oxygen consumed at submaximal speeds. In 1930, David Dill and his colleagues were among the first physiologists to suggest that there are marked differences in the amount of oxygen different athletes use when running at the same speeds, and that these differences in "economy" of oxygen use are a major factor explaining differences in running performance of athletes with similar VO2 max values. For example, research has shown that, while Kenyan runners have VO2 max and LT values similar to their American/European counterparts, the Kenyans are more economical, possibly due to their light, non-muscular legs that interestingly resemble those of thoroughbred race horses. The heavier your legs, the more oxygen it takes to move them.
RE is probably even more important than the LT in determining distance running performance because it indicates how hard you're working in relation to your maximum ability to use oxygen. For example, if two runners have a VO2 max of 70 milliliters of oxygen per kilogram of body weight per minute and an LT pace of 7 minutes per mile, but Jack uses 50 and Martin uses 60 milliliters of oxygen while running at 7:30 pace, the pace feels easier for Jack because he is more economical. Therefore, Jack can run faster before using the same amount of oxygen and feeling the same amount of fatigue as Martin. I have yet to see a runner who has superior RE who does not also have a high VO2 max and LT.
1.1 Raise Your Threshold
Sample workouts to raise your lactate threshold (LT):
1. Continuous runs at LT pace, starting at about 3 miles and increasing up to 7 to 8 miles (or about 45 min.) for marathoners.
2. Intervals @ LT pace with short rest periods, such as 4 to 6 x 1 mile @ LT pace with 1 min. rest.
3. Shorter intervals at slightly faster than LT pace with very short rest periods, such as 2 sets of 4 x 1,000 meters @ 5 to 10 seconds per mile faster than LT pace with 45 seconds rest and two min. rest between sets.
4. Long, slow distance runs with segments run at LT pace (for marathoners), such as 12 to 16 miles with last 2 to 4 miles @ LT pace or 2 miles + 3 miles @ LT pace + 6 miles + 3 miles @ LT pace.
1.1a What's your LT Pace?
LT pace is about 10 to 15 seconds per mile slower than 5K race pace (or about 10K race pace) for slower runners (slower than about 40 minutes for 10K). If using a heart rate (HR) monitor, the pace is about 75 to 80 percent of maximum HR. For highly trained and elite runners, LT pace is about 25 to 30 seconds per mile slower than 5K race pace (or about 15 to 20 seconds per mile slower than 10K race pace) and corresponds to about 85 to 90 percent max HR. For many, it corresponds closely to the race pace they can sustain for one hour. The pace should feel "comfortably hard."