- What is running?
- What's the history of running?
- Why run?
- What are the health benefits of running?
- What are the fitness benefits of running?
- What about running and burning fat?
- What about running and losing weight?
- What about running vs. walking for weight loss?
- What about running outdoors vs. a treadmill?
- What about the risk of running injuries?
- How much running do I need to do?
- What are proper running techniques?
- What shoes should I wear when running?
- What type of foot strike do I have?
- What are some other tips on buying running shoes?
- What type of clothing should be worn during running?
- How do I go about getting started?
- Where can I find resources on running?
That day, for no particular reason, I decided to go for a little run. So, I ran to the end of the road, and when I got there, I thought maybe I'd run to the end of town. And when I got there, I thought maybe I'd just run across Greenbow County. And I figured since I run this far, maybe I'd just run across the great state of Alabama. And that's what I did. I ran clear across Alabama. For no particular reason, I just kept on going. I ran clear to the ocean. And when I got there, I figured since I'd gone this far, I might as well turn around, just keep on going. When I got to another ocean, I figured since I've gone this far, I might as well just turn back, keep right on going. When I got tired, I slept. When I got hungry, I ate. When I had to go, you know, I went. My mama always said you got to put the past behind you before you can move on. And I think that's what my running was all about. I had run for three years, two months, 14 days, and 16 hours.
That's from the movie Forrest Gump, when Forrest (played by Tom Hanks) runs in scene after scene after scene. The idea symbolized, among other things, the beginning of the running craze that spread across the country in the 1970s. Since then, running has captured the attention of millions of Americans. Thousands of road races and marathons occur each year, and running is the sixth most popular exercise in the United States. But you don't need to run marathons, or run continuously for three-plus years like Forrest, to gain the benefits of running. Thirty minutes a day will do! In this article, I will tell you what all the fuss is about. I'll review the history of running, how to get started, what to wear, proper posture, where to run, the risks of running, and one or two more quotes from Forrest.
What is running?
Here's the Merriam-Webster dictionary definition of running: to go steadily by springing steps so that both feet leave the ground for an instant in each step. That's the key: both feet are in the air at once. During walking, one foot is always on the ground. Jogging is running slowly, and sprinting is running fast. I'll discuss both jogging and running in this article.
What's the history of running?
Human beings started walking and running some 4-6 million years ago when we evolved and rose from all fours. Ten thousand years ago, hunter-gatherers like the Tarahumara Indians in Mexico, ran 15-75 miles a day on the hunt. But it was Pheidippides (490 BC), an ancient "day-runner," who put running on the map. Pheidippides is purported to have run 149 miles to carry the news of the Persian landing at Marathon to Sparta in order to enlist help for the battle. Scholars believe the story of Pheidippides may be a myth (if the Athenians wanted to send an urgent message to Athens, there was no reason why they could not have sent a messenger on horseback), yet the myth had legs (no pun intended) and was the genesis of the modern marathon. It was the first running of the marathon (26 miles 385 yard) in the modern Olympic Games of 1896 in Athens that commemorated Pheidippides' historic run. Throughout the latter part of the 19th century, track and field, including running, took a prominent place in the field of sport. By the late 1800s, children in school were competing in running races. In the 20th century, it was the famous black sprinter Jesse Owens who, in the 1936 Olympics in Nazi Germany, shattered Hitler's dream of proving the superiority of the Aryan race by winning gold medals in the 100-meter dash, 200-meter dash, and the 400-meter relay. More American were spectators of running than they were participants during the era of Jesse Owens, but that has changed in the past 35 years. Runners like George Sheehan, Bill Rodgers, Jeff Galloway, Alberto Salazar, and Grete Waitz (winner of nine NYC marathons from 1978-1988 and inspiration to all women to get out there and run!) promoted running through their athletic success, and now running is solidly a popular activity for exercise as well as for sport.
- Newsman: Sir, why are you running?
- 1st Reporter: Why are you running?
- 2nd Reporter: Are you doing this for world peace?
- 3rd Reporter: Are you doing this for women's rights?
- Newsman: Or for the environment?
- Reporter: Or for animals?
- 3rd Reporter: Or for nuclear arms?
- 2nd Reporter: Why are you doing this?
- Forrest Gump: I just felt like running.
There's a bug about running that you catch. It could be the exhilaration of propelling your body through space, or the pounding on the ground that sends sensation up your bones all the way to the pleasure centers in your brain, or it could simply be the sheer satisfaction of having done something good for yourself. Whatever it is, running can be addictive. The psychologist Mihaly Csikszentmihalyi might describe the experience of running as "flow," the state of mind in which you are fully immersed in what you are doing. Or it could be what William Glasser calls, "positive addiction," where you perform a repetitive activity without self-criticism or judgment that has a beneficial effect on your mind and body.
What are the health benefits of running?
The benefits of vigorous exercise are well described. The American College of Sports Medicine Position Statement on Exercise is a document chock-full of studies proving that vigorous exercise yields plenty of health benefits. One of the major points of the position statement is that there is a dose response to exercise; that is, the more you do, or the harder you do it, the more benefit you accrue. But this point is not to discount moderate exercise. You get plenty of benefit from moderate exercise, it's just that vigorous exercise seems to accrue even more benefit. The ACSM report makes it clear that "many significant health benefits are achieved by going from a sedentary state to a minimal level of physical activity; [but] programs involving higher intensities and/or greater frequency/durations provide additional benefits. For example, it was shown in one study that individuals who ran more than 50 miles per week had significantly greater increases in HDL cholesterol (the good fat) and significantly greater decreases in body fat, triglyceride levels, and the risk of coronary heart disease than individuals who ran less than 10 miles per week. In addition, the long-distance runners had a nearly 50% reduction in high blood pressure and more than a 50% reduction in the use of medications to lower blood pressure and plasma cholesterol levels."
What are the fitness benefits of running?
Cardiorespiratory fitness (aerobic fitness or "cardio") is the ability of your heart to pump stronger and more efficiently and your muscles to use oxygen more efficiently. As you get more aerobically fit, your heart will pump more blood and oxygen with each beat (this is called "stroke volume") and your muscles will extract (or consume) more oxygen. For instance, if you have 100 oxygen molecules floating around in your bloodstream, a conditioned muscle might consume 75 molecules, whereas a deconditioned muscle might only consume 30, or even fewer than that. In fact, elite distance runners can be as much as three times more efficient at consuming oxygen than sedentary individuals. Running improves your aerobic fitness by increasing the activity of enzymes and hormones that stimulate the muscles and the heart to work more efficiently.
What about running and burning fat?
For years, I've been asked if running burns more fat than other exercises. My hunch was that it might, but there was never any proof. In particular, I was always perplexed by the fact that swimming burns so many calories (in some cases even more than running), yet when you look at the physiques of Olympic swimmers and compare them to elite long-distance runners, you see a more defined, cut and leaner physique on the runner. Adjusting for something called self-selection, where individuals of a certain body type might select a specific sport (for example, lean people might choose long-distance running because they already have the body type for it), I never fully understood why swimmers and some other endurance athletes weren't quite as lean as runners. Then I read a study comparing fat burning in running and uphill walking to cycling and it turned out that fat burning was 28% higher during running and walking uphill than it was during cycling. The authors of the study aren't sure why this is so, but it is suggested that the pounding of weight-bearing activities like walking and running may cause more fat burning than a seated exercise like biking, or an activity like swimming where there is no pounding at all. This is intriguing research, but more needs to be done before we truly sort out these issues.
What about running and losing weight?
To my knowledge, there are no studies to show that runners lose more weight than individuals who do other types of exercise. However, running certainly does burn lots of calories, and if you're running regularly, you might decide not to eat as much figuring why do it if you're putting all that energy into running. But even if you ran a marathon every day, you wouldn't lose weight unless you consumed fewer calories than you burned. The bottom line to losing weight is burning more calories than you consume, no matter how much exercise you do.
What about running vs. walking for weight loss?
According to the laws of physics, you should burn the same number of calories whether you walk or run the same distance. However, there is recent research to show that running one mile burns approximately 30% more calories than walking one mile, and it's true whether you run outdoors or on a treadmill. The research is mixed, and so it's hard to know for sure if you'll burn more calories running than walking. My take on it is that it doesn't matter whether you walk or run during weight-loss efforts because you'll lose weight as long as you reduce your calories enough to burn more than you are consuming, no matter how much, or what type of exercise you do. What is important is that you maintain some type of exercise once you reach your goal weight, because it's generally accepted that exercise is the single best predictor of keeping your weight off. Whether you walk or run won't matter. The key is to do something.
What about running outdoors vs. a treadmill?
You'll get equally fit running on a treadmill or outdoors. In fact, many distance-running athletes use the treadmill to save their legs from the pounding of roadwork. But there is a slight difference in energy expenditure (calories burned) between the two; outdoor running burns slightly more calories than treadmill running at the same speed due to lack of air resistance on the treadmill. Researchers studying this phenomenon found that setting the treadmill at 1% elevation equals things out. I advise all of my clients to set the treadmill at 1% so that treadmill walking or running mimics outdoor exercise.
What about the risk of running injuries?
No one has a crystal ball and can predict who will or will not get injured from running. Until recently, it was believed that running less than 20 miles per week lowered the risk of injury, but that recommendation was based on a small number of studies. Now, however, a new study called a meta-analysis (a study that reviews many studies on one subject) evaluated studies of running injuries and published the following interesting results:
- The overall incidence of lower-extremity injuries varied from 19.4% to 79.3%, thus the range is wide, which implies that it is difficult to predict who will get injured.
- The most predominant site of injury was the knee.
- Higher age was reported as a significant risk factor to incur running injuries in four high-quality studies, but two other high-quality studies reported that higher age was a significant protective factor. Therefore, at this time, the evidence is conflicting and so it's not clear if running when you are older will cause or protect you from injury.
- Increasing distance during the week does not appear to be a risk factor for injury, and in fact, in some studies, it was shown to be protective against injury. However, this may be because only strong runners increase their mileage and they may be less prone to injury. More research needs to be done before conclusions can be drawn about increasing mileage and the risk of injury.
- Running more than 40 miles per week was a risk factor for both male and female runners to incur lower-extremity running injuries, although the risk was higher for males, perhaps because they tend to weigh more than women.
- There appears to be no association between the use of a warm-up and lower-extremity injuries. This means that stretching beforehand may not reduce your risk of injury. This is not a surprise, as there is virtually no research to show that stretching prevents any type of injury.
- The most common site of lower-extremity injuries was the knee (7.2% to 50.0%), followed by the lower leg (9.0% to 32.2%), the foot (5.7% to 39.3%), and the upper leg (3.4% to 38.1%). Less common sites of lower-extremity injuries were the ankle (3.9% to 16.6%) and the hip/pelvis (3.3% to 11.5%).
- A history of previous injuries is a risk factor for running injuries. Runners with previous injuries should pay extra attention to signs of injuries, avoid overtraining (like exceeding 40 miles per week), and take time to fully recover from their injuries.
In summary, the most important findings from this research are that (1) running more than 40 miles per week is a risk factor for injury, (2) previous injury is a risk factor for future injury, and (3) the most common site of injury is the knee*.
* I recommend straight leg raises to strengthen the thigh muscles and protect the knee against injury. To do them, lie on the floor on your back, one knee bent, the other straight, hands palm-down under the buttocks to support the low back. Contract the quadriceps on the straight leg, then raise the leg to the height of the other knee. Pause one to two seconds at the top, then lower the leg but do not allow it to touch the floor. Repeat 10-15 reps, three sets. You can use ankle weights if these are very easy. Start with one pound and work up. You should always be able to do 10-15 reps. As you get stronger, you can progress to leg extensions, leg curls, leg presses, squats, and other leg exercises.
How much running do I need to do?
The American College of Sports Medicine Position Statement on Exercise that I mentioned earlier recommends that all healthy adults should do the following:
- Frequency of training: three to five days per week
- Intensity of training: 55/65%-90% of maximum heart rate (HRmax)
- Duration of training: 20-60 minutes of continuous or intermittent aerobic activity
- Mode of activity: any activity that uses large muscle groups, which can be maintained continuously, and is rhythmical and aerobic in nature (for example, walking-hiking, running-jogging, cycling-bicycling, cross-country skiing, aerobic dance/group exercise, rope skipping, rowing, stair climbing, swimming, skating, and various endurance game activities or some combination thereof)
Running and jogging are right there, and they count!
What are proper running techniques?
Sure, you could go out and just run, and there's no evidence to suggest that that won't work just fine. But if you're struggling with running, or something just doesn't feel right, then it might be worth paying attention to your form. The following tips for correct running form are adapted from Runner's World Magazine and Jeff Galloway. I'll start at the top and work down.
Head: You should look forward toward the horizon when you run. To do that, keep your head on top of your spine and do not bend forward or look down at your feet. Your head weighs at least 13 pounds, and you don't want it dragging you down with forward-head posture! The emphasis is on keeping your body erect, because you're fighting gravity when you lean forward (it's okay if you look down at the ground at least 20 feet ahead of you since you won't lean forward to do that). Keep your face and jaw relaxed, too; it's okay if they shake and bounce as you run.
Torso: As Jeff Galloway says, "Your torso's only along for the ride." Track coaches describe the ideal posture as running tall, which means that you stretch yourself up to full height with no strain from the torso. This will allow you to breathe maximally and put your body in the optimal biomechanical position for moving forward.
Hips: Your hips are close to your center of gravity and will be in proper alignment if your torso and head are aligned. If you lean forward, your hips will tilt forward too and that will strain your lower back.
Legs: Sprinters lift their knees very high when they run, but for distance running, and even shorter distances, keep your knees low. It takes a lot of energy to lift your knees, and even running a mile will be tough if you do so. Instead, quicker ankle action will help you increase your speed.
Ankles: Your ankles are efficient levers that have the potential for great power when you run. Feel your calf muscles and ankles work as you push off on each step.
Arms: Arms should remain close to the body and swing forward and back and not across your body to minimize torso rotation (the exception is Bill Rodgers who had memorably wide elbows when he ran). Your hands should not cross the midline of your body (imagine a line drawn right down the center of your chest). The swing should be held low, elbows bent at a 90-degree angle and relaxed. You should do most of the work with your lower arms; the upper arms should not move very much.
Hands: Cup your hands by gently touching your thumb to the top half of your index fingers. It's as if you are holding a small bird that you don't want to fly away but you don't want to squeeze too tight either.
Some additional tips
Breathing tips: Lift your chest up and out while running to breathe deeply. Also exhale fully; this will increase your inhalation. Keep some focus on your torso, neck, and shoulders, too. Tight muscles will constrict breathing, so work on maintaining a relaxed posture when you run.
Running uphill: Maintain your rhythm and the same level of effort but shorten your stride and slow down as you climb.
What shoes should I wear when running?
Although research does not necessarily prove that shoe type prevents running injuries, I suggest running shoes since they do provide support in the midsole and padding and reinforcement in the heel. You hit the ground with two to three times your body weight when you run, and so I think it's prudent to wear footwear designed specifically for the activity.
The type of foot you have and your running style will determine the shoe that you purchase. The first thing to do is determine your foot strike. Foot strike describes how your foot hits the ground. Normally your heel lands first (heel-strike), followed by mid-foot strike and flattening of the arch to absorb impact (very important), then the forefoot strike (front of your foot), and finally the push-off to the next stride. Soft heel-strikes with a smooth gait pattern and some flattening of the arch will reduce the impact on the foot and cause less stress in joints as high up as the hip (the ankle bone is indeed connected to the hip bone!). There are three types of foot strike:
- Pronated foot strike. Pronation is the term to describe when your arch flattens on foot strike (for example, when you have flat feet) and causes your foot to invert, or roll in. Excessive pronation will cause your ankle and leg to twist and can lead to stress fractures, shin splints, and other lower-extremity injuries. You're probably a pronator if the inner edges of your shoes wear out.
- Supinated foot strike. Supination is the term to describe high arches that don't flatten. This is a problem because if your arch doesn't flatten and your foot doesn't roll in at all, then you lose shock absorption on foot strike. Excessive supination can lead to ankle sprains, Achilles tendinitis, plantar fasciitis, and iliotibial band syndrome. You're probably a supinator if the outer edges of your shoes wear out.
- Neutral foot strike: An efficient amount of flattening of the arch is called "neutral" foot strike. This provides plenty of shock absorption and enough energy for you to have a powerful push-off.
What type of foot strike do I have?
You can tell by the wear pattern of your shoes, particularly on the heel, if you pronate or supinate. If your shoe wears out on the outside, then you probably supinate, and if it wears out on the inside, then you probably pronate. You can also ask a salesperson at a reputable shoe store to evaluate your gait and foot strike, or you can have your doctor or podiatrist do this. You can also try the wet test at home. To do it, wet your bare foot, and then step on a piece of paper or other surface that will show your footprint. Stand normally when you do this with slight pressure toward the front of your foot. You're a pronator if most of your foot hits the floor, a supinator if very little of your foot hits the floor, and neutral if the footprint is somewhere between pronation and supination.
Avoid shoes with excessive cushioning because they lack stability and motion control. Shoes that feel as soft as bedroom slippers, lack support, or are excessively bouncy are not a good choice for over-pronators. Instead, purchase shoes with firm midsoles and pronation-control features. I also recommend over-the-counter full-length arch supports for over-pronators. Powerfeet and Superfeet full-length insoles are two good choices and can be located online.
Supinators and individuals with high arches
Purchase cushioned shoes that do not limit motion. Your foot doesn't shock absorb very well if you have high arches and you supinate, and too much stability and control in the shoe will decrease shock absorption even more.
Wear any type of running shoe that feels comfortable. Your foot strike is efficient with a healthy amount of arch support and shock absorption when your foot is neutral.
Speak with your doctor or consult with a podiatrist if your feet hurt when you run. It will be difficult to stay motivated to exercise if your feet hurt. Your doctor can help.
What are some other tips on buying running shoes?
- Find a reputable running-shoe store in your area, preferably one where the salespeople are runners.
- Bring your running socks and try both shoes on. If one foot is larger than the other, buy the larger size.
- If the store is reputable, they'll let you take the shoes outside for a test run.
- Shoes should feel comfortable right away-there's no "breaking in" period. Don't buy shoes if seams or stitching can be felt. That can cause blisters, calluses or other injuries.
- Get fitted for running shoes at the end of the day when your foot is at its maximum size.
- Allow about one-half inch between the end of your longest toe and the shoe's end-with wiggle room for all toes.
- The shoe should be as wide as possible across the forefoot without allowing heel slippage. Experiment with the lacing to get a proper fit.
- When is it time for a new pair of shoes? Shoes may lose their cushioning after three to six months, depending on how often your wear them and how far you run. I suggest taking your current shoes to the shoe store and compare how they feel to new shoes. If you immediately notice the difference, then it's probably time for new shoes.
- I've had lots of personal success using trail-running shoes. Trail-runners are built for running on trails in the woods, over roots and rocks, so they have exceptional padding and support as well as wider grooves in the soles for gripping. Montrail and Vasque are two companies that make them. I recommend them for anyone, and especially so if you are a heavy runner (hard foot strike), or if you've had running injuries in the past.
Expect to pay anywhere from $60 to $120 dollars for a new pair of running shoes. Like anything, running shoes go on sale. So, look for the best prices when possible. Some of the popular brands, in no particular order, are: New Balance, Nike, Saucony, Asics, Brooks, and Reebok. There are more (see the shoe finder resources at end of the article), but what you need to do first is determine your foot type, then look for the shoe(s) that match it, then try the shoe on and see how it feels.
What type of clothing should be worn during running?
Shorts don't need to be complicated. The most important features are the fabric. It should be fast-wicking polyester to keep you dry. Some shorts have pockets to stash your keys or some money, and many have a drawstring to keep them from falling off when you run! Expect to pay $25 to $60 dollars for quality running shorts.
Leggings are good for when it's chilly. They come in tights that fit snugly that are made of polyester (spandex or Lycra), or they can fit looser and softer with combinations of polypropylene and other fabrics to make them feel almost like cotton. Select whichever feels most comfortable to you. All of these fabrics will keep you dry and warm. Expect to pay $75 to $125 for quality leggings.
Select a tank top or T-shirt depending on what feels most comfortable. Again, the fabric should be fast-wicking polyester to keep you dry.
How do I go about getting started?
Programs for running
The simple thing to do is get out there and jog or run for five to 10 minutes. Pace yourself, slow down if you get out of breath, and keep moving. I like a five-minute out, five-minute back plan. From your starting point, jog five minutes, turn around, and jog back five minutes. Done! Of course, not everyone can jog for 10 minutes to start, and that's okay. Try an informal interval-training method as a way to get started if jogging straight for 10 minutes is beyond your ability. Keep in mind that the most important thing is just to get started. You can always add more later on. Here's an interval plan that will get you started.
- Select the amount of time that you plan to jog/run for, let's say, 30 minutes.
- Start with a five-minute brisk walk to warm up.
- When you feel ready, start to jog. If you get out of breath, slow down and keep jogging, or walk again until you catch your breath. This could take one to two minutes.
- Once you've caught your breath, go ahead and jog again until you feel you've had enough. At that point, walk again.
- Repeat this series of walking/jogging intervals for 30 minutes, or whatever duration you select.
If you stick with this method, you'll find over time that you can increase the jogging intervals and decrease the walking intervals until you can jog for the entire 30 minutes.
Formal training schedules
If you prefer a more formal training program, you can organize your workout into specific intervals or ratios of work to active recovery (for example, work: active recovery). For instance, if you can jog for 30 minutes at 5.5 mph, try jogging for three minutes at that speed, then increase the speed to 6.0 mph and jog for one minute, then jog again for three minutes at your normal speed, then jog again at 6.0 mph for one minute, and so on until you reach your time limit. The work: active-recovery ratio in this example is 1:3. You can increase the work portion each week by 30 seconds and decrease the active-recovery time by 30 seconds, and if you follow that plan weekly, you will be jogging your whole workout at the faster speed before you know it! You can get even more specific and use your heart rate to determine your intervals. Heart rate is an excellent indication of how hard you are working. For example, if your heart rate at 5.5 mph is 70% of your predicted maximum, then start at that speed and increase either the speed, and/or elevation if you're on a treadmill, so that your heart rate increases to 85% for one minute, then back to your jogging speed that causes your heart to be at 70% of maximum for three minutes (1:3 ratio like the example above). Over time your conditioning will improve and then your heart rate will be lower at the higher speeds and you can spend more time at the higher speeds and less time in the active rest period. You can always vary the ratios if they turn out to be too hard or too easy. A good starting ratio is 1:3. Check the resources at the end of this article for additional training plans.
Although, as I mentioned, there is no persuasive research to show that stretching will prevent injuries, it does feel good, and that may be reason enough to stretch. Go ahead and stretch your calves, quadriceps, hamstrings, and low back, before and after your runs, and see what you think.
Where to run
The good news is that you can run just about anywhere. Find a track or a trail in the woods or a route on the street near where you live. Running in another city when you're traveling is a great way to see new sites and check out your environment. You can also call the local running club in the location you're traveling to for tips on scenic places to run. You might also consider joining your own local running club. The camaraderie of running with others is nice; it can be fun, motivating, and can help you stick with it if you're struggling a bit. It's also good to be a club member if you're looking for a training partner.
You might be interested in running in organized races. If so, check with your local running club for a race schedule near where you live. Road races are a great way to stay motivated, monitor your progress, and collect cool T-shirts as a trophy for your success! Road races come in many distances. There are 3.2 mile (a "5K" where K means kilometer), 5.0 mile, and 6.2 mile races (10K),as well as half marathons (13.1 miles) and marathons (26.2 miles). Most beginners should start with shorter races to get the feel of it and then tackle the longer ones.
How fast do I run?
You can determine your pace per mile by using a "pace calculator." Many Web sites have them. Check the resources at the end of this article for links.
The finish line
So there you have it; the low-down on running. I recommend giving it a try if you have any interest. Start slowly, just a few minutes if that's all you can do. You can always build up over time. The important thing is just to get started. In the words of the immortal Bruce Springsteen, "Baby we were born to run!"
Where can I find resources on running?
Health Solutions From Our Sponsors
National Health Interview Survey 1998
Eaton S et al. The Paleolithic Prescription. Harper and Row, 1988.
Mihaly Csikszentmihalyi. Flow: The Psychology of Optimal Experience. Harper Perennial, 1990.
William Glasser. Positive Addiction. Harper Colophon Books, 1976.
The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Healthy Adults. Medicine & Science in Sports & Exercise, Volume 30, Number 6 June 1998.
Williams, P. T. Relationship of distance run per week to coronary heart disease risk factors in 8283 male runners: the national runner's health study. Arch. Intern. Med. 157:191-198, 1997.
Achten J, et al Fat oxidation rates are higher during running compared with cycling over a wide range of intensities. Metabolism. 2003 Jun;52(6):747-52.
Kram R., et al. Energetics of running: a new perspective. Nature. 346:265-267, 1990.
Hall C et al Energy Expenditure of Walking and Running: Comparison with Prediction Equations. Med Sci Sports Exerc. 2004 Dec;36(12):2128-34.
Jones AM, et al. A 1% treadmill grade most accurately reflects the energetic cost of outdoor running. J Sports Sci. 1996 Aug;14(4):321-7.
van Gent, BRN, et al. Incidence and determinants of lower extremity running injuries in long distance runners: A systematic review. Br J Sports Med. 2007 May 1.
The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Healthy Adults Medicine & Science in Sports & Exercise, Volume 30, Number 6 June 1998.
Galloway, Jeff. Galloway's Book on Running. Shelter Publications, 1984.
Nigg, B.M. The role of impact forces and foot pronation: a new paradigm. Clin J Sport Med. 2001 Jan;11(1):2-9.
Cavanagh, P.R. & LaFortune, M.A. (1980). Ground reaction forces in distance running. J Biomech. 13, 397-406.
Clarke, T.E., Frederick, E.C., and Cooper, L.B. (1983). Effect of shoe cushioning upon ground reaction forces in running. Int J Sports Med. 4, 247-251.
Munro, C.F., Miller, D.I., and Fuglevand, A.J. (1987). Ground reaction forces in running: a reexamination. J Biomech. 20, 147-156.