A couple weeks ago, I gave you 17 reasons why you should walk more this year , citing dozens of studies in my attempt to convince you that walking is a healthy, effective endeavor for everyone and anyone. But it’s not the only thing you should be doing if you can help it. If you have the ability, I strongly believe that you should also be sprinting – at least (and maybe at most) once a week. The effects of regular sprinting on your health, your body composition, your fitness, your strength, and your susceptibility to disease are so impressive that it’d be foolish not to. I’ve said it before and even enshrined it in the Primal Laws  to accentuate its importance, but here it is again: you should sprint more  this year.
Why, though? Let’s hear some specific, science-based reasons to get up and move as fast as possible:
1. It preferentially burns body fat.
Weight loss isn’t just about eliminating any old kind of body mass. It’s about losing body fat while preserving or even gaining muscle and bone. Sprinting appears to be excellent at eliminating body fat without the negative impact on muscle mass commonly seen with excessive endurance training . A recent study  found that a single sprint session can increase post-exercise fat oxidation by 75%. Not that this is a surprise, but even in young adults with an intellectual disability, sprinting improves body composition by reducing body fat .
2. It’s anabolic (that means it can increase muscle mass and strength).
An acute bout of sprinting increased dihydrotestosterone  in healthy young men, while in overweight young men , a sprinting program increased lean mass in the legs and trunk. (In one study , men and women did three 30 second all-out sprint intervals on the stationary bike with 20 minutes of rest in between each sprint. Muscle biopsies were taken from their quads and analyzed for markers of protein synthesis – how muscle gets laid down.
3. It’s even more anabolic in women than men.
Yeah, yeah, you don’t wanna “get all big and bulky.” I know. But ladies, it won’t happen to you unless you’re somehow using an exogenous source of anabolic hormones to reach supraphysiological levels that you’d otherwise never reach naturally. More lean mass for you means more “tone,” less body fat, and more strength. In the previously mentioned study , female protein synthesis was up by 222%, male by 43%.
4. It makes you better at accessing body fat during other types of exercise.
Sprinting primes the substrate utilization pump, so to speak, for other activities. In one study , a two week program of cycling sprint interval training increased the rate of (body) fat oxidation (and decreased the rate of glycogen utilization) during subsequent lower intensity sessions in women.
5. It builds new mitochondria.
The basic function of our mitochondria  is to extract energy from nutrients to produce ATP, the standard energy currency of our body. More mitochondria, more power available to our brain and our body, more fuel burned, more energy produced. It’s a generally good idea to have healthy, numerous mitochondria, and scientists are constantly trying to figure out how to preserve or increase their numbers because so many degenerative diseases are characterized by malfunctioning mitochondria. Well, sprinting is one way to make more . A single bout of 4×30 second all-out cycling sprints activated mitochondrial biogenesis  in the skeletal muscle of human subjects in one study. Shorter sprints work, too. In fact, a program consisting of three sets of 5 4-second treadmill sprints with 20 seconds of rest in between each sprint, done three times per week for four weeks up-regulated molecular signaling associated with mitochondrial biogenesis .
6. It even works if you go slowly.
Allow me to expand on that statement: it even works if you go slowly because you’re pushing a heavy weighted sled. If that doesn’t sound like an advantage to you, consider someone who can’t run a flat-out sprint on a flat surface because of prior joint injuries. Pushing a heavy sled (or a car) slows the person down, thus reducing the joint impact, without making the exercise any less intense. Research shows that heavy sled pushing is extremely effective .
7. It’s more efficient than endurance training.
Obviously, sprint training takes less time to do than endurance training. But did you know it’s just as effective in many regards in a fraction of the time? Sprinting three times a week (4-6 times per session) was just as good  as spending five days a week cycling for 40-60 minutes at improving whole body insulin sensitivity, arterial elasticity, and muscle microvascular density.
8. It takes way less time than you think.
A 30 second all out sprint is “just” 30 seconds, but it’s a hellish 30 seconds. A single hill sprint isn’t too bad, nor are two or three, but when you hit the eight, nine, ten sprint range, it gets rough. You will feel it after. Still better than slogging it out for an hour and half, mind you. I get the sense that most people think for any training to be effective, it has to hurt – even if only for twenty seconds or so. Actually, when you sprint, extremely brief intervals work very well. In this study , for example, subjects cycle-sprinted for a mere 5 seconds at a time and actively rested for 55 seconds in between sprints (that’s where you’re just casually pedaling on the cycle, equivalent to walking after a running sprint); that was enough to increase the maximum amount of work they were able to perform in 30 seconds. Instead of walking down the beach, I’ll sometimes traverse it in ultra-short sprint intervals: sprint for 5 seconds, walk for 20, sprint for 5, and so on. I don’t really even get winded doing this. Or if there’s a short (<10 meters) but steep hill, I’ll sprint up it, walk down, and repeat about a dozen times.
9. It’s a good excuse to get to the beach.
Doing your sprints on sand  makes them more effective (and harder). A recent study  found that sprint interval training sessions performed on sand resulted in better performances in subsequent training bouts, beating out grass as a training surface. I’ve also found that beach sprints enable post-training water plunges, regardless of water temperature .
10. It works for overweight people.
Sprinting may be the most daunting exercise of all for overweight people. How can moving that fast be safe or healthy? Well, there’s evidence that sprinting is extremely effective in this population. In a 2012 study (PDF ), a group of overweight female students followed a 12-week sprint program consisting of 8-16 200 meter sprints done three days a week. After the program, body fat and body weight had gone down significantly, insulin sensitivity had improved by 100%, and V02max had increased. Another study , this time in overweight/obese men, found that a sprinting program (this time on a cycle) increased fat burning at rest while decreasing carb burning at rest – exactly what an overweight person needs to achieve to start burning body fat and become fat-adapted . The men also lost significant amounts of waist and hip fat.
11. It works for elderly people.
Oldsters needn’t stick with 2.5 pound dumbbells and “stretching workouts.” They can derive great benefit from high intensity interval training . Sure, they might go a bit slower than the rest of us. They might do better on exercise bikes than tracks. But they can still do it.
12. It improves glucose control and insulin sensitivity.
Diabetics , take heed. Sprint training  improves insulin sensitivity , improves hyperglycemia in type 2 diabetes , and lowers the postprandial glucose response in diabetics . You gotta start doing it if you’re not already.
13. It lowers high blood pressure.
Okay, while you’re sprinting, you’ll probably have sky-high blood pressure . That’s okay, that’s just an acute spike – it happens with any type of exercise. Overall, sprint training appears to have the most potential of any exercise modality for the long term resolution of hypertension .
14. It’s safe for people with heart disease.
Heart disease patients interested in improving their cardiovascular health are often told to start jogging or something similarly unpleasant. Why not sprinting? We already know it’s more effective against heart disease risk factors , and high intensity interval training has been shown to be safe in heart disease patients , particularly when they keep the intensity high and the duration low  (15 seconds or thereabouts). Check with your doctor first, of course, just to be safe (but prepare yourself for the “jogging” lecture).
15. It comes in many forms.
When people hear “sprinting,” they think of 100 meter flat sprints on the track. Those are effective, sure, but they’re not the only way you can reap the benefits of sprint training. You can run hills (easier on the joints and more intense overall). You can cycle (easier on the joints and proven to work in dozens of sprinting studies). You can do it in the pool (either running in water or swimming). You can row or use the elliptical. Heck, if you loathe “cardio” of any kind you can probably get sprint-esque effects from lifting weights really quickly (think doing a set of 20 back squats or something similar). Upper body interval training works for general fitness in elderly hip replacement patients , for example. There’s something for everyone, which means there are almost no excuses not to sprint.
That’s what I’ve got. There are probably more reasons to sprint, but I think the 15 I discussed are a good start. So get to it!
What about you guys? Why do you sprint? What are you hoping to get out of it? What have you already gotten out of it? Let us know in the comment section!