Articles with information useful to developing runners are reproduced below courtesy of their authors.
Stride Right and Improve Your Run
Is Your Stride 'Stiff' Enough?
July 18, 2005
Your running stride length is a useful tool in your training that, unlike many other factors influencing performance, remains largely within your control. When optimized, stride length can help keep you going stronger, faster, and better protected from many common injuries.
Interestingly, professional runners have frequently been shown to utilize shorter strides than their less accomplished, but nevertheless experienced, counterparts. In a related study of collegiate runners, researchers observed a decrease in running stride lengths from their first to their final year. How do you avoid the impulse to overstride, then?
Stride length
Stride length, both natural and optimal, increases at faster speeds. The key is to discover the way your optimal stride length feels, and it will follow you at any running speed. Renowned exercise physiologist, coach, and Running & FitNews editorial board member Jack Daniels, Ph.D., has observed repeatedly that leg turnover naturally determines stride length.
Focusing runners on reaching 180 steps per minute is an excellent way to move their stride length into the optimal range, without unduly placing all of their focus on running form. For many people, this running cadence is faster than they are used to attaining, but it achieves several noteworthy results.
Daniels writes, "The main problem associated with a slower turnover is that the slower you take steps, the longer the time you spend in the air." This displaces your body mass higher, and leads to a greater ground landing shock. A shorter stride means a lighter stride. Daniels advises that optimal stride rate should feel like you are running "over the ground, not into it."
Try to get the feeling that your legs are part of a wheel that just rolls along ... Try counting the strides of one leg for one minute and see how close you can get to 90. Alternately, you may count arm swings or count steps for 30 seconds and multiply the result by two. So optimal stride length and running turnover are really two sides of the same coin.
Ground-push: Pawback
The corollary to this revelation is the importance of your ground-push. Toward the end of the swing phase of the running gait, once your leg has swung fully forward, forcefully pull it down and back as the foot makes ground contact. Continue this backward pull then push of the leg as you move toward pushoff.
Accentuate the backward push against the ground, and not just a forceful push downward, otherwise you'll bounce up and down rather than propel your body horizontally across the ground. This is called pawback, and it is an important component of running economy.
Swing phase
To discuss yet another alterable factor that influences running economy, it's useful to further examine the swing phase. Following toe-off, contraction of the hamstrings brings the foot up and back toward the buttocks. The bent knee then straightens as the leg swings out ahead of the body's center of mass.
More energy is required to swing a limb with its weight distributed toward the end than concentrated near the joint, which helps explain why studies of optimal running economy have shown that larger upper legs and smaller (and therefore lighter) feet and calve muscles improve efficiency. A more flexed knee during this phase also improves running economy, as the forces required to bring the leg out in front will remain less with a compact leg position.
Quadriceps flexibility
Quadriceps flexibility is a key determinant of knee flexion. To stretch your quads, standing on one leg, keep the thigh of the other perpendicular to the ground and slowly bring your foot up against your buttocks. Over time, the less resistance your quadriceps impose on this action, the less energy you'll have to expend to bend your knee (which reduces the weight you're required to move at the end of your limb during swing phase).
The combination of a light, wheeling turnover, minimized bouncing, and greater quadriceps flexibility and knee flexion can help you achieve the right stride length and cadence for improved speeds at reduced injury risk, whether you're on an easy recovery run or in the midst of an intense track workout.
References:
Run Strong ed. by Kevin Beck, Human Kinetics, Champaign, IL, 2005
Improving Stride Mechanics by Jack Youngren, pp. 12-20
Creating Leg Turnover and Raw Speed by Greg McMillan, pp. 26-27
Daniels' Running Formula by Jack Daniels, Ph.D., Human Kinetics, Champaign, IL, 1998, pp. 80-82
Drink Up!
Shelley Scott
July/August 2003
Chicago Athlete
We All Need Water - The Question is 'How Much?'
A common belief is that every adult needs eight,
8-ounce glasses of water per day, also known as 8x8. Saying that the optimal fluid intake for every person is eight, 8-ounce glasses is almost like recommending that everyone should wear a size-8
running shoe. This shoe may work for many people, but my size 9 1/2 feet would be mighty cramped!
Despite the pervasiveness of the 8x8 recommendation, if you go looking for scientific evidence to support this theory, you'll likely not find it. In fact, after extensive review of scientific research
and interviews with leading sports nutrition experts, Dartmouth Medical School researcher Heinz Valtin, MD, found no scientific proof for the 8x8 recommendation. (Details of his review were published
in the November 2002 issue of the American Journal of Clinical Physiology.)
Just where did the 8x8 rule come from? Dr. Valtin suggests that it may have roots in the Food and Nutrition Board of the National Research Council, which suggested that digestion and body functions
require approximately 1 milliliter of water for every calorie consumed. For an average person who needs approximately 2,000 calories per day, this would be 2,000 milliliters, which equals 2 liters, or
approximately eight, 8-ounce glasses. What the 8x8 rule neglects, however, is the fact that the Food and Nutrition Board also suggested that much of our basic fluid needs are met from water contained
within the foods we eat. Many foods contribute substantially to meeting our fluid needs. Fruits and vegetables, for example, are a large percentage fluid. Strawberries, for example, are 92 percent
water, raw carrots are 88 percent water, and bananas are almost 75 percent water.
For many sedentary people, 8x8 may actually be more fluid than they need, though surpassing fluid needs somewhat is likely not harmful for most.
Does the lack of evidence for the 8x8 rule mean that we don't need to worry about fluid intake?
Absolutely not!
Many active people and athletes might need more than 8x8. Fluid needs vary from one person to another, from one climate to another, from one sport to another. A "one size fits all" recommendation like
8x8 is not the best advice.
Water plays a variety of roles in the body, and dehydration, even mild, can substantially diminish athletic performance. Water's functions include regulating body temperature, processing and
transporting nutrients, excreting waste products, and lubricating joints.
Just how do you know how much water you need for your climate and your sport? Perhaps the best practical advice, though far from glamorous, is to monitor your urine frequency and color. Very pale or
clear urine is a sign of adequate fluid intake. Darker urine doesn't necessarily mean you are dehydrated, but it suggests that you are headed in that direction and should be hydrating more. However,
urine color may not be accurate for people who take mega-doses of B vitamins. Because B vitamins are water-soluble, the excess from mega-doses that your body doesn't need will be excreted in urine and
possibly make it darker even if you are well-hydrated.
Other general recommendations for fluid intake among athletes have been suggested: (Remember, however, that these are guidelines, and that individual needs vary by body size, length of exercise, and
climate. Use your training as a time to learn how much fluid your body needs in response to different exercise conditions.)
* Approximately 16-20 ounces 2-3 hours before exercise
* 5-10 ounces about 15 minutes prior to exercise
* 5-10 ounces every 15-20 minutes during exercise * 6 ounces after exercise.
For exercise lasting more than 60 minutes, an electrolyte replacement sports drink should be alternated with regular water.
Another way to test whether you are hydrating enough during physical activity is to weigh yourself before and after exercise. Any weight you lose during exercise is fluid loss, not true fat-tissue
loss. Each pound you lose during exercise represents underhydration of about 20 ounces, which must be replaced.
Is it possible to drink too much water? Though it may seem strange, it's true that excessive water intake can lead to hyponatremia, a condition in which blood sodium levels get dangerously low.
Although anecdotal reports of athletes dying from severe hyponatremia are shocking and scary, dehydration remains a more common problem. Don't be afraid of drinking fluids, just be smart about using
electrolyte-replacement drinks during events in which you lose a lot of sweat, and this should prevent hyponatremia.
Fitness Water Won't Hurt, But It's Not A Clear Choice
It seems more and more products are crowding the bottled water aisle at the grocery store. In addition to the traditional sports
drinks, a slew of "fitness" or "vitamin" waters are now marketed. The ingredients in these products vary, but most contain a small amount of flavoring and sucrose along with supplemental vitamins, and
occasionally herbs.
It seems more and more products are crowding the bottled water aisle at the grocery store. In addition to the traditional sports drinks, a slew of "fitness" or "vitamin" waters are now marketed. The
ingredients in these products vary, but most contain a small amount of flavoring and sucrose along with supplemental vitamins, and occasionally herbs.
Although the added vitamins in fitness waters likely won't hurt you, they probably don't offer a substantial benefit. The typical fitness water may give you a small percentage of your daily need for a
few vitamins, but you'll get more than this amount of vitamins from a healthful diet.
Drink a glass of orange juice and eat bowl of Cheerios for breakfast, and you've already surpassed the amount of vitamins provided in most of these fitness waters. Plus, these foods also give you
several phytonutrients ("plant nutrients") that help promote health and prevent disease. Orange juice contains limonene, which is being studied for its cancer-preventive qualities; and oats (in
Cheerios) contain saponin, which can help lower cholesterol. You'll miss out on these and other phytonutrients if you rely on supplements or fortified fitness waters for your vitamins.
The fitness waters do offer flavor, and for someone like myself who finds regular water "boring," a little flavor helps me drink more fluid. It's more cost-effective, however, to add a slice of lemon
or lime, or a splash of 100 percent fruit juice to my water bottle.
Whether herbs added to some fitness waters offer any benefit is not clear. Evidence is sparse for the role of herbs in health. The amount of the herbs added to fitness waters may be substantially less
than the doses found in herbal supplement pills, making the potential benefit from these waters even more questionable.
Oxygenated waters are another relatively new resident to the water aisle. Manufacturers of these products would like you to believe that these products will oxygenate your muscles. However, oxygenated
waters don't end up oxygenating your muscles or blood much, according to research conducted at the University of Wisconsin and published last year in the journal Medicine and Science in Sports and
Exercise. From a nutrition point of view, a more beneficial way to keep your muscles oxygenated is to make sure you consume adequate iron, folate, vitamin B-6, and vitamin B-12 to maintain healthy red
blood cells and hemoglobin levels--the role of hemoglobin in our blood is transport of oxygen throughout the body.
By Matt Fitzgerald
For Active.com
February 14, 2006
When you watch world-class runners like Berhane Adere and Kenenisa Bekele in action, the last word you might conjure up to describe their running style is "stiff." These runners look smooth and fluid, not stiff. It's the back-of-the-pack runners shuffling along in their lock-kneed manner who look stiff.
Nevertheless, a certain type of stiffness is actually a hallmark characteristic of the best runners' strides. Elite runners like Adere and Bekele have the most of it, while lesser runners like us could use a lot more of it. The type of stiffness I'm referring to is the type that physicists talk about in relation to springs.
The human body does in fact function as a sort of spring during running, and just as a spring with adequate stiffness will bounce more efficiently than a spring that's too loose, a runner who exhibits sufficient muscular stiffness when his or her foot strikes the ground will run more efficiently than a runner whose muscles are too loose on impact.
A spring works by reusing energy. When it falls to the ground from a given height it compresses, which converts the "kinetic" energy of the fall into "potential" energy stored in the form of tension in the spring. As the spring returns to its natural length it converts this potential energy back into kinetic energy in the form of a directional force directed into the ground. As a result, the spring bounces back up into the air.
The spring effect
Something very similar happens when we run. As the foot makes contact with the ground, tendons and elastic components of certain muscles stretch beyond their natural length, thereby capturing and storing energy from the impact.
As these tissues return to their natural length, this energy is released. Exquisitely timed and coordinated muscle actions direct the energy back into the ground, sending the runner's body upward and forward.
Few runners realize just how much energy they are able to reuse thanks to this spring effect. Research has shown that runners consume oxygen at a rate that is sufficient to produce only about half of the energy that is needed to run at any given speed. The other half is provided by the spring effect.
A stiffer spring is able to reuse more energy than a looser spring because it returns energy to the ground faster. A looser spring stretches and compresses too slowly, allowing more stored energy to dissipate as heat or friction. Top runners spend less time with their foot on the ground than lesser runners, in part because their superior muscle stiffness allows them to return more energy to the ground faster.
Ironically, this is one reason why the elite runner's stride looks smoother and more fluid. These runners spend more time "floating" in the air and get more of their energy for free, so they don't have to produce as much energy through muscle contractions to run at any given speed.
Muscle stiffness
What contributes to muscle stiffness? Part of it comes from the actual elastic properties of the muscles and tendons themselves. These can be enhanced through proper training.
The other part comes from running technique. A runner with excellent technique is able to coordinate his or her muscle actions in a way that enables them to reuse more energy for forward thrust.
For example, top runners do a better job of pre-stretching and stiffening certain muscles (particularly the hamstrings) just before the foot makes contact with the ground, which enables the runner to capture more energy in the muscles and tendons, return it to the ground more quickly, and direct more energy backwards, resulting in more forward thrust.
Three steps to put a spring in your step
So, what can you do to become a stiffer, springier runner? Besides following a well-structured running program, there are three things you can do: 1) improve your running technique, 2) do plyometric exercises, and 3) change your shoes.
1. The most common energy-wasting stride error in runners is overstriding -- that is, landing heel-first with the foot far ahead of the body's center of gravity. To correct this error, practice tilting your entire body very slightly forward as you run, which will encourage you to land more flat-footed with your foot underneath your body. Don't lean forward from the waist -- tilt forward at the ankles.
Another helpful technique change is to begin retracting your lead leg the instant before your foot lands as top runners do instead of waiting until your foot is firmly planted on the ground to begin generating backward thrust, as most of us do.
2. Recent studies have shown that runners who supplement their running with jumping drills (i.e. plyometrics) are able to increase their muscle stiffness during running and thereby improve their running economy and lower their race times. One example of an effective plyometric exercise for runners is single-leg box jumps: stand on one leg and leap up onto a 12-18" box repeatedly.
3. Most running shoes reduce running stiffness in two ways: Their cushioning material absorbs and dissipates energy before our muscles and tendons can capture it, and they encourage us to overstride. To minimize the adverse effects of running shoes, I recommend that you use the lightest and least-cushioned running shoes you can use comfortably.
My favorite running shoe of all-time is the Nike Free, which has very little cushioning, so it wastes little energy and discourages heel-first landing. While Nike promotes this shoe as a foot-strengthening tool to be used no more than 20 minutes a week, I run 50 miles a week in mine, and many other runners use them as everyday training shoes. The Nike Free isn't for everyone, but you'll definitely run springier in the most minimal running shoe you can get away with wearing.
Matt Fitzgerald is the author of several books for triathletes and runners, including Performance Nutrition for Runners (Rodale, 2006). His online training plans for runners are available at www.trainingpeaks.com/cuttingedge.