Some runners have funny ideas about the meaning of the word “anaerobic”. It’s not their fault, though, because even many exercise physiologists harbor an outdated understanding of aerobic and anaerobic metabolism. Often I hear athletes talk about “going anaerobic” when their running intensity exceeds the anaerobic or lactate threshold, which is a moderately high but not extremely high intensity—one that most fit individuals can sustain for a full hour. This expression—“going anaerobic”—reflects an incorrect belief that the working muscles get their energy either entirely aerobically or entirely anaerobically, whereas in fact they almost always get their energy from both systems simultaneously, with the balance shifting gradually from aerobic toward anaerobic as exercise intensity increases. And indeed, exercise intensity must increase far above the lactate threshold before the muscles even get a majority of their energy anaerobically. If you were to run as far as you could in two minutes (in other words, as hard as you could for two minutes), your muscles would get about half of their energy aerobically during that effort.
This much is understood by most exercise scientists. But what all too many of these professionals don’t know is that most of what is classified as anaerobic metabolism is actually just incomplete aerobic metabolism. Recent research has shown that roughly 75 percent of the lactate that is produced through the anaerobic breakdown of glucose is further broken down aerobically within the muscles cells to release energy. The rest is shuttled to other organs and tissues, where it is either broken down aerobically to supply energy or converted back into glucose for future aerobic breakdown.
If anaerobic glycolysis is reclassified as incomplete aerobic glycolysis, as it should be, then virtually the only truly anaerobic metabolism that occurs in the muscles is the breakdown of high-energy phosphates. This type of metabolism becomes predominant only at the very highest exercise intensities, such as during 100-meter sprints.
While true anaerobic metabolism has only a tiny place in running, anaerobic fitness—or speed and power—is critical to distance running performance. The average runner thinks of factors such as VO2max, fat-burning capacity and running economy as being the keys to running performance and tends to forget about pure speed. But if you set aside your prejudices and look at the speed of world-class distance runners, you will see that pure speed is at least as important as the other performance keys. Most 2:11 marathoners are capable of running a sub-50-second 400m. Folks, that is flying!
Research confirms the importance of pure speed to distance running performance. A study by Finnish researchers found that 20m sprint times were nearly as powerful a predictor of 5,000m race times as VO2max. Studies by the same group have demonstrated that explosive power training effectively improves distance-running performance.
It may seem strange that anaerobic training enhances distance-running performance when there is virtually no anaerobic component to actual distance racing, but it’s true. The primary reason appears to be that anaerobic training increases the bounciness of the stride, so that the feet come off the ground faster and more forcefully. This improves running economy, because half of the energy that propels forward motion during running is supplied not by the body but by the force of impact, and the less time the feet are in contact with the ground, the less of that free energy is lost.
In short, for runners the point of performing types of training that involve anaerobic metabolism is not to developing anaerobic metabolic capacity but rather to increase the speed and power characteristics of the muscle fibers.
Therefore, true anaerobic efforts deserve a bigger place in your training than they have in your races. There are three specific types of anaerobic training that you should be sure to include in your training regimen: sprints, plyometrics and weightlifting.
It’s amazing how few runners ever run at full speed—I mean full speed, the way you ran virtually every time you ran as a kid. All-out sprinting is not only exhilarating, as every six-year-old knows, but it is also great training, even for distance runners. Sprint training increases stride power and running economy, benefits that transfer all the way down to marathon speed and below. Sprinting also forces your body to confront the technical limiters in your stride, resulting in better form.
A little sprinting goes a long way. Elite coach Brad Hudson has his athletes perform a set of 4-12 steep hill sprints of 8-10 seconds once a week after an easy run. The steep hill serves to reduce the risk of hamstring and Achilles tendon injuries.
This is about all the sprinting you ever need to do, except at times when increasing your raw speed is a major fitness priority, when you will also want to perform repeated flat sprints of 100 to 300 meters, also once a week. Start with shorter sprints and extend them gradually over several weeks in order to first increase your maximum speed and then blend your new speed with endurance.
Developed in the 1960s by Eastern Bloc sports coaches, plyometrics consists primarily of jumping exercises designed to enhance the power of the legs. Studies have shown that adding a small amount of plyometrics to the training regimen of endurance athletes improves performance. A 2003 study by Australian researchers found that the addition of plyometrics to the training of high-level runners for six weeks resulted in an average 2.7-percent improvement in 3K race times.
An example of a good plyometrics exercise for runners is the single-leg box jump. Stand on your left foot facing a sturdy platform 12 to 18 inches high (such as stacked aerobics steps). Bend your left leg, swing your arms back then forward to generate momentum, and jump up onto the platform landing on your left foot. Do not allow your right foot to touch the platform. Immediately jump back down, also landing on your left foot. Continue jumping for 30 seconds with the left leg, then switch to the right.
Few runners care to make time to add plyometrics workouts to their training regimen. But you don’t have to. As an alternative, incorporate some single-leg running into one or two of the runs you’re already doing every week. Start by running on just your right leg for 10 strides and then on just your left leg for 10 strides. Gradually increase the number of strides you do on each leg until you reach 30 strides per leg. You will notice that it gets easier to go longer on one leg, which is a sign that your legs are adapting to the stress and your stride is becoming more efficient.
As with sprinting and plyometrics, a little weightlifting goes a long way for runners. If you select your exercises well and really get after them, you can gain significant performance benefits from just three, 15-minute weightlifting sessions per week.
The mistake that many runners make is going too light with their loads. There is a common misconception among runners that they should use lighter loads and greater numbers of repetitions than others do because, after all, they are endurance athletes. But the point of going to the gym is not to get more of what you are already getting from your endurance training. Distance running does not build strength. Building strength enhances running performance in a way that distance running cannot match. The most effective way to build strength is with heavy loads. Runners should lift heavy loads!
Studies prove it. For example, in a recent study by Norwegian researchers, a group of 17 runners experienced a 21-percent increase in aerobic endurance after doing heavy barbell half-squats for eight weeks. How heavy? The runners did four sets of just four repetitions with their 4RM max load—that is, with the greatest amount of weight that each runner could lift four times.
Here’s an effective total-body strength workout for runners that includes just four exercises and takes no more than 15 minutes to complete.
Heavy Barbell Squat – 3 sets
Cable Low-High Pull* – 1 set pulling left to right, 1 set pulling right to left
*Stand with your left side facing a cable pulley station with the handle fixed at ankle height and pull the handle upward and across your body with both arms in a movement that somewhat resembles shoveling snow.
Single-Arm Dumbbell Snatch – 1 set with each arm
Cable Low-High Pull** – 1 set pulling left to right, 1 set pulling right to left
** Stand with your left side facing a cable pulley station with the handle fixed at head height and pull the handle downward and across your body with both arms in a movement that somewhat resembles chopping wood.