Hungry vultures circled overhead, wide black wings casting menacing shadows under the blazing sun. In my exhaustion-induced delirium, their gaze seemed to follow me too closely as I neared the end of my very first “long run.” I looked forward to collapsing in the cool grass, but changed my mind and found a picnic table instead. Didn’t want those vultures to get any ideas.
I wouldn’t consider 7.5 miles a long run nowadays, but years ago when I started training for my first half-marathon, two laps around the lake at Watkins Mill State Park was a feat of endurance. So, for those folks in our running club who feel challenged as we move into longer runs on Saturday morning, I can relate.
But I promise, you’ll survive. You’re amazing … you just don’t know it yet.
Long, slow runs are a necessary ingredient in the training recipe of a runner. You might occasionally skip a mid-week workout, but the long, slow run is mandatory for anyone who plans to run any distance beyond a 5K.
Of course, “long” and “slow” are relative. My rule of thumb is that my favorite run of the week, typically on Saturday morning, is about twice the distance of my weekday runs, at a pace that’s 1-to-2 minutes-per-mile slower.
My second rule is that I reward myself with espresso and a giant cookie afterward. A long run burns so many calories (I typically burn more than 1,000 calories in this workout) that you can indulge without guilt.
Why are long runs so important?
- Running requires as much mental as physical stamina.
Long runs provide a mental workout. They develop focus to maintain concentration over a long period of time. Just as important, they train your brain to appreciate what your body is really capable of achieving. You see, your brain is risk-averse. As soon as the energy stores in your muscles begin to deplete, your brain starts firing signals to your muscles to slow down or stop. This is perceived as fatigue. The reality is that your muscles can continue to keep going; you have plenty of fuel (and strength) to continue running. But your brain panics. By deliberately ignoring those panic signals and running beyond this fatigue boundary, you train your brain to realize that you can do it, and survive. Next time, your brain won’t panic so quickly. The perceived fatigue will be lessened and delayed. You will be able to run farther before exhaustion as you grow stronger both physically and mentally.
- Time on your feet.
Related to the first point; your training needs to replicate the experience of the race. If you’re running a marathon, you’ll be on your feet for several hours. Long runs develop confidence that you can finish the course. The only way to become accustomed to running for such long periods of time is to, well, run for long periods of time. No shortcuts here. My longest runs (22 milers) are paced to take about the same length of time as my marathon finish.
- Burning fuel more efficiently.
Your body will burn primarily two sources of fuel while running – glycogen (which is stored in your muscles and liver) and fat. Glycogen is the body’s first choice, because it burns more efficiently. But it only lasts a short time before it’s depleted. Your body doesn’t burn fat as efficiently, but there is more of this fuel available (unfortunately!). So your body prefers to burn glycogen for fuel, and only turns to fat when glycogen starts running low. At that point you slow down, because fat is a less efficient fuel. But with practice, your body can learn to both 1) store a larger amount of glycogen, and 2) burn fat more efficiently. By training your body to burn a higher proportion of fat, and to burn it more efficiently, you are building a larger fuel tank. Which means you’ll be able to run farther before you run out of gas. Long runs – lasting more than an hour – transform your body into a more efficient fuel-burning engine.
- Building Body Infrastructure
Some other beneficial physical changes also occur during long runs (and to a lesser degree, in other training runs as well). For example, your heart is pumping oxygen-rich blood to your muscles, and this oxygen is directly delivered by the capillaries that surround muscle fibers. When those muscles demand more oxygen, your body actually builds more capillaries to meet the demand. With more capillaries per muscle fiber, oxygen and fuel is delivered more efficiently. Waste products that are produced in working muscles are removed more quickly.
Muscle fibers are either slow-twitch fibers or fast-twitch fibers. As the name implies, folks who are born with more slow-twitch fibers can run farther, while those born with more fast-twitch fibers can run faster. And it is genetic – you can’t do anything to increase the proportion of slow-twitch to fast-twitch muscle fibers to improve your natural endurance or speed. What you can do, though, is train your fast-twitch muscle fibers to behave more like slow-twitch muscle fibers, thus increasing endurance.
Cells in your muscle fibers have small factories – mitochondria – that use fuel to produce energy. Long runs accomplish several important objectives: Increase the size of your mitochondria (that is, build bigger energy factories), increase the number of mitochondria in your muscle fibers (that is, build more factories) and increase the efficiency of mitochondria (that is, speed up production in those factories). More, and larger, mitochondria means you can produce more energy and maintain a faster pace over a longer time. (Mitochondria produce energy aerobically, as opposed to producing energy anaerobically, which is important for endurance runners – but sort of complicated and beyond the scope of this post.)