Physiological Determinants of Distance Running Performance
Maximal oxygen uptake (VO 2max), lactate threshold, and running economy are three physiological variables related to distance running performance. The interplay of these factors largely determines performance in events from 5 Km to the marathon. Elite runners have "good" to "exceptional" values for all three factors, while good runners will have a mixture of "fair" to "exceptional" values.
Maximal Oxygen Uptake
To move the body requires energy. Distance running is aerobic, meaning that oxygen is used to produce most of the energy required to run for long periods. The higher your maximal oxygen uptake, the more energy you can produce and, consequently, the faster you can run. In distance running it is best to express VO2max relative to body weight (ml of oxygen used per kg of body weight per minute of exercise), while in cycling, or running shorter distances, it is best to express VO2max in absolute terms (liters or milliliters per minutes.) VO2max is best expressed in consideration of body weight, excess body fat negatively affects VO2max. For example, Joe weighs 154 lb (70 kg), is 20%fat, and has a VO2max of 2.8 L or 40 ml/kg/min. If he loses 10 pounds of fat (this make him 15% body fat), he will now weigh 144 lbs (65.9 kg) and have a VO2max of 2.8 L or 42.4 ml/kg/min. By losing excess fat weight, Joe has improved his relative VO2max by 6%.
VO2max increases with training. Unfit people who start training will show the most improvement. Intensity is the most important training factor affecting VO2max. The longer you have been running and the better your aerobic condition, the higher your running intensity needs to be in order to see an improvement in your VO2max. More experienced runners probably need to train at 90-100% of VO2max to see an increase in VO2max.
Lactate Threshold
Endurance events are not run at 100% of maximal oxygen uptake. Generally, the longer the race, the slower we run because we cannot maintain higher levels of oxygen consumption. For example, races of 0.5, 1, 2, and 4 hours are run at 70-100%; 50-90%; 40-85%; and 30-70% of VO2max, respectively. Some individuals run at a higher % VO2max during a race because they have a higher lactate threshold.
Lactic acid is produced and builds up in the blood when a significant amount of energy is produced anaerobically, or without oxygen. Lactic acid interferes with the ability of muscles to use oxygen and produce energy. During running, when all or most of the energy you are generating is produced via oxygen, there is very little lactate in the blood. As you run faster and pass a "threshold", you begin to produce a significant amount of energy anaerobically and lactate begins to build up in the blood. Suppose that your lactate threshold occurs at 60% of your VO2max At 40%, 45%, 50% and 55% of your VVO2max all of your energy is produced aerobically, and there is very little lactate in the blood. Then, at 60% of your VO2max, you begin to produce a significant amount of energy anaerobically, resulting in a significant build-up of lactate in the blood. The lactate threshold occurs at a higher % of VO2max in well trained individuals (70 - 85% VO2max) than in untrained individuals (40-60% VO2max).
In general, the % of VO2max that you can maintain during a race is determined by your lactate threshold. A marathon is run at about lactate threshold, and a 10K is run at a pace slightly above (about 2 mph) lactate threshold. In our testing, we did not measure lactate threshold. Measuring lactate threshold requires drawing blood during an exercise test, which we did not do during your test. Instead, we determined your ventilatory threshold, the point at which ventilation increases exponentially, which is a good reflection of lactate threshold.
Distance runners tend to peak in performance after years of training, usually when they are older in age. One reason for this is that lactate threshold tends to improve slowly with the years of training. To improve your lactate threshold requires doing some of your running at or just below your lactate threshold.
Ed Eyestone, a former world class distance runner, recommends the following workouts to increase your threshold. Tempo runs at or just below your threshold (or about 12 sec per mile slower than current 10K race pace) starting at 20 min and then working up to 4-5 miles. These are best done on a flat course. Tempo intervals—(a) 1000 meter repeats at threshold pace with 60 seconds of recovery between repeats. Start with about six and workup to 10. (b) 1600 meter repeats at threshold pace with 60 seconds of recovery between repeats. Start with about 3 and workup to 5. (c) 4-6 2,000 meter repeats with 90 seconds between repeats. If you need more recovery time or if you can’t maintain your pace during all of the intervals, you ran the first ones to fast. Two 10-minuterepeats at your current 10K race pace with 4-6 min between the repeats.
Running Economy
Running economy is the amount of energy needed to run at a certain pace. If you have a good running economy, you use less energy to run at a given speed than someone with poor running economy. If two runners have the same VO2max and are able to run a race at the same % VO2max, the runner with the better running economy will be running faster. Less is known about the underlying mechanisms of running economy than is known about VO2max or lactate threshold. Running economy usually improves naturally with training, but primarily at your training speeds. In other words, if you do all of your training at an 8:00 min/mile pace, but race at 7:00 min/mile, your running economy will be better at 8:00 min/mile than at 7:00 min/mile. This is one reason it’s important to do some training at and faster than race pace. Over striding can cause poor running economy, but research shows that most runners naturally choose their most economical stride length. Heavy weight training and explosive weight training or plyometrics have also been shown to improve running economy.
Putting It All Together
Researchers indicate that there are two laboratory measures that are best able to combine the 3 factors discussed above. In other words, the best single, quantifiable factor used for predicting distance running performance is either maximal running speed or running speed at lactate threshold. The faster you can run at lactate threshold, or your maximum speed during a test such as this, the faster your race pace will be in race distances from a 5K to the marathon.
Monitoring Training Intensity
We have mentioned that intensity is a critical factor in improving VO2max, and lactate threshold. How can you monitor your intensity? There are three ways: (1) we have given you your running speed at ventilatory threshold. This should work reasonably well if you are running on a track, but hills and wind are factors that must be considered, (2) We have also given you your heart rate at your ventilatory threshold. The advantage of using heart rate is that this allows you to adjust your pace for hills and wind. In addition, your recommended heart rate doesn't change as you improve, (3) finally, you must listen to your own body. You've probably noticed that if you are running at a pretty easy speed and then run a little faster, it doesn't really feel that much harder. You run a little faster and it still doesn't feel that much harder. But eventually, when you run just a little faster, it feels quite a bit harder. You've just started running faster than your lactate threshold!
Using Lactate Threshold to Estimate Running Performance
Well-trained runners can run a 10K at a pace that exceeds their lactate threshold by 5 meters/min.
Speed at LT (min/m) |
Estimated 10K Time |
|---|---|
5:00 |
30:30 |
5:30 |
33:30 |
6:00 |
36:30 |
6:30 |
39:30 |
7:00 |
42:30 |
8:00 |
48:30 |
VO2max (ml/kg/min) |
Potential 10K Time |
|---|---|
>70 |
33:00 or faster |
65-69 |
33:40-36:15 |
60-64 |
36:50-39:30 |
55-59 |
40:10-42:45 |
50-54 |
43:25-46:00 |
45-49 |
46:40-49:15 |
40-44 |
49:50-52:30 |
<39.0 |
53:10 or slower |
References
- Bassett D Jr, E. Howley. Limiting factors for maximum oxygen uptake and determinants of endurance performance. Medicine and Science in Sports and Exercise 32(1) 70 - 84, 2000.
- Coetzer P., et al. Superior fatigue resistance in elite black South African distance runners. Journal of Applied Physiology 75(4): 1822 - 1827, 1993.
- Joyner M. Physiological limiting factors in distance running. In: Hollosky JO, editor. Exercise and Sport Sciences Reviews. Vol 21. Baltimore , MD : Williams & Wilkins, 1993.
- Powers S, E. Howley. Exercise Physiology, 4th edition New York : McGraw Hill, pp. 391-395.
- Scott, B., J. Houmard. Peak running velocity is highly related to distance running performance. International Journal of Sports Medicine. 15: 504 - 507, 1994.