The snow melts. Your Gore-Tex suit is back in the closet. Spring marathons loom on the horizon, and runners everywhere are putting in long runs to prepare. But, why run long? What do these annual rites of spring do for you?
There are at least 7 physiological benefits to long runs, and there are other advantages as well. Let's start with the physiology.
#1: Surround your muscle fibers with capillaries. Capillaries are the smallest blood vessels. Several capillaries typically border each muscle fiber. They are the transportation system for the cell, bringing oxygen and fuels in, and waste products such as carbon dioxide out. Long runs increase the number of capillaries per muscle fiber, which improves the efficiency of delivery and removal.
#2: Shuttle oxygen with more myoglobin. Myoglobin in your muscle cells serves a similar function to hemoglobin in your blood-it carries oxygen from the cell membrane to the mitochondria. Long runs increase the myoglobin content of your muscle fibers, so more oxygen can reach the mitochondria to produce energy.
#3: Make mighty mitochondria. The mitochondria are the aerobic energy factories in your cells. Long runs increase the number and size of the mitochondria in your muscle fibers. With more mitochondria, you can produce more energy aerobically, and maintain a faster pace.
#4: Increase aerobic enzyme activity. Enzymes in the mitochondria speed up aerobic energy production. Long runs increase the activity of these enzymes, which improves the efficiency of the mitochondria. So you not only have more and bigger energy factories, but they are also more efficient.
#5: Fill the tank with glycogen. Long runs teach your muscles to store more glycogen. Glycogen is the storage form of carbohydrate, and when you run low, you slow down. How do long runs lead to greater glycogen storage? Running long distances uses up the glycogen in your muscles. Our ancestors were at risk of being eaten when they ran out of glycogen. Fortunately, glycogen depletion stimulates the muscles to store more glycogen-to help prevent future depletion. Because the faster you run the more glycogen you burn, running your long runs at a reasonable pace is a more effective way to deplete your glycogen stores (and hence stimulate the muscles to store more) than jogging.
#6: Burn more fat. Long runs not only increase your ability to store glycogen, they also allow your muscles to conserve glycogen by burning more fat. As you increase your endurance training, you rely more on fat and less on carbohydrates at a given speed. As a result, your glycogen stores last longer. In a marathon, that means that "the wall" moves closer and closer to the finish line.
#7: Muscle fiber masquerade. The higher the percentage of slow twitch fibers in your muscles, the greater your likelihood of success in the marathon. That's because slow twitch muscle fibers naturally have more of the 6 adaptations we've already discussed than do fast twitch fibers. Well, for those of you not genetically endowed with a high proportion of slow twitch muscle fibers, there is good news. Long runs give your fast twitch fibers more of the characteristics of slow twitch fibers. So, although top sprinters will never become world-class marathoners, with enough training their fast twitch fibers will gain some of the beneficial attributes of slow twitch fibers. There may be hope for Flo-Jo after all!
Finally, there are psychological and even spiritual benefits to the long run. By running long, you simulate what your legs and body will go through in the marathon. When your hamstrings tighten up 23 miles into the race, it helps to have experienced a similar feeling in training, so you realize that you can shorten your stride a few inches and keep going. During your long runs, you also experience the connection of the mind and body. As you learn to relax and concentrate, you will begin to look forward to extending your body's limits.
How far is long enough?
There is no scientific evidence here. A clear tradeoff exists, however, between running far enough to stimulate physiological adaptations and remaining uninjured. Experience suggests that steadily building up your long runs to 21 or 22 miles will maximize your chances of reaching the marathon in top shape and healthy. Try adding 1 mile to your long run per week, skipping every third week. For example, if your current long run is 14 miles, your long run schedule would be: week 1 (15 miles), week 2 (16 miles), week 3 (no long run), week 4 (17 miles), week 5 (18 miles), week 6 (no long run), week 7 (19 miles), week 8 (20 miles), week 9 (no long run), then a 21 or 22 miler week 10. Ideally, the longest run should occur 3-4 weeks before the marathon, followed by a taper.
Run long, and be confident that you are training correctly to prepare yourself-physiologically, psychologically, and perhaps spiritually-for the rigors that lie ahead. As race day approaches, remember to cut back your training, apply vaseline as necessary, and think positive. A successful spring marathon to everyone!
(This column originally appeared in Running Times Magazine.)