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How well are we equipped to run? - 2. Lower legs and feet. April 12 2016, 0 Comments

From our previous discussion, our upper legs are designed to help us with locomotion on the ground, and I'd like to now build the case that we are actually designed to run.

Casting our attention south to the lower legs and feet, and again comparing with the apes, we can see that we have a very chunky calf muscle and a considerably bigger achilles tendon.

Tendons connect bones to muscles and are elastic, often being placed to absorb and store energy for later use. For walking, where we normally plant the heel and then roll forward on the foot to pushing off into the next step, there doesn't seem to be much need for a large, impact-absorbing tendon. For running, on the other hand, especially if we accept the case for a front-foot landing, the absorption of energy as the heel is lowered warrants a very much larger tendon, such as we have. The elastic energy stored can then be used for the push-off into the next stride.

The case becomes stronger when considered with the structure of the foot. One of our feet has 26 bones, 33 joints and more than 100 muscles. Many of these are located in the arch, which acts as a bridge between the ball and heel of the foot. When we land on the front foot in running, the muscles in the arch and the achilles tendon together tense and absorb the impact of the step so that the heel lands much more lightly. This prevents a jarring impact at the heel being transferred upwards to the ankle and knee and the lower back. One of the best illustrations of this are the videos taken by Dr Daniel Lieberman's group at the skeletal lab at Harvard University. Follow the link for a heel strike. You can see that the total impact of landing is about two and a half times the body weight, when the heel lands about one and a half times the body weight occurs in the first, jarring impact by the heel, shown by a vertical line on the impact/time trace at the bottom.

With a front-foot landing, the impact trace has a much more gradual slope, showing a steady transfer of weight, rather than a sudden one. Furthermore, adding a big wad of padding to the sole of your foot doesn't significantly reduce the sudden impact of a heel strike.

So our calves, achilles tendons and feet are admirably suited to provide us with a cushioned ride during running. And we have other equipment that helps us to run, as we shall discuss in the next blog. In the mean time you might like to check out our  ZEMgear shoes, which protect your feet, but allow them and your legs to run as nature intended.

 


What are the relative values of running and walking? March 12 2016, 0 Comments

You know that running is more intense than walking, and believe in your heart of hearts that it is doing you good. But what does the evidence say? The benefits of different durations and intensities (walking and running) of exercise is discussed by Wen et. al. in the Journal of the American College of Cardiology (2014, 64:5).

It seems that, even in very small doses, walking and running are beneficial in reducing cardiovascular disease and lowering the risks of diabetes and hypertension. The benefits are on a sliding scale that increases as the amount of exercise goes up, but the biggest increase in benefit is at the beginning of the curve, where the amount of exercise is small (figure 1, after Wen et al.).

Figure 1: Relative benefit in reduced mortality for average daily running or walking time.

The implications from this are that benefits can come from relatively small changes - good news for those who have difficulty finding the time to do long work-outs. It also means that beneficial exercise can be built into your day by, for instance, getting off the bus a couple of stops earlier and walking the last part of the journey into work.

For those of you who want to ease yourself into spring with running or hiking, and would like to do so with less shoe and more you, ZEMgear Hero and Apex shoes are warmer for the still cold weather, but you should graduate fairly quickly to Terras as it warms into summer.

Good running and walking all!


The importance of rest September 16 2015, 0 Comments

Browsing through YouTube the other evening, I came across Dr James O'Keefe, a cardiologist, delivering a talk on TED, in which he advises against overdoing exercise, a rather unexpected comment to come from a cardiologist. He compares exercise to a drug - a fantastic drug that protects against heart disease, diabetes, depression and a multiple of other conditions. However, as with all drugs, it has an optimal dose range, and if you overdo it, it can do more damage than good.

The human body is a remarkable piece of apparatus. It improves by a process of damage and repair. When you exercise beyond your limit, micro-tears develop in your muscles, and when these are repaired, the muscle is built back stronger and better than before. This is the process of getting fit, and it requires a period of rest before exercise is repeated to allow the repair to take place, or the tears simply get bigger. The heart is a muscle like any other, and according to Dr O'Keefe, sustained exercise beyond about an hour results in micro-tears or damage. If you take some rest days afterwards, these repair themselves, better and stronger than before.

The issue comes with long-term, long-distance runners who train regularly enough for the repair process not to take place. Their hearts stretch to accommodate the sustained increased blood that they pump, and the tears do not repair so that scar tissue is formed. He cites a study of some 50'000 people which shows that runners have a 19% longer life expectation than sedentary people, but that when they run over 30km average a week, this benefit cancels out. The result also applies to speed - up to 10km/h provides benefit, but pushing to 12km/h sees it go away. Finally, running two to five times a week provides the benefit, but running seven days a week takes it away again. The Copenhagen Heart Study, tracking 20'000 people since 1976, confirms these results. Joggers have a 44% lower mortality rate and live on average 6 years longer than non-runners - provided they run at a slow to average pace for one to two-and-a-half hours or two or three times per week.

Some of you will always prefer to run far and fast and die happy. With these learnings you can choose your own destiny and the good news is that if you choose to change and slack off now, the heart repairs itself and returns to normal. For the rest of us, exercise is a remarkable therapy, and running up to 30k per week at a moderate pace will make us healthier and happier. You can find Dr O'Keefe's talk here. Good running all!


Fixing outside knee pain August 18 2015, 0 Comments

It is fairly common for runners to get knee pain, and I'd like to take a look at a specific form of this in which the pain comes on the outside of the knee. This is probably because of tightness.

The iliotibial band consists of the the iliotibial tract, a tendon which attaches to the pelvic girdle at the top and the tibia below the knee at the bottom. The gluteus maximus (buttock) muscle inserts into it top-rear, and the tensor fascieae latae muscle at the top-front. This combination is responsible for sideways stability in standing, walking and running. Just above its lower insertion, the iliotibial tract passes over the lateral epicondyle, a bony bump on the side of the knee. Under normal circumstances, it will glide back and forth over this without issue, but if the iliotibial band is tight the resulting friction can lead to inflammation and pain.

How does it get to be too short? Running too much too early can result in the tendons shortening, especially if you don't routinely stretch them when warm after running. Aim to increase either distance or speed (but not both) by about 10% per week for a comfortable progression to fitness, and slow this down if you get untoward aches and pains.

The iliotibial band is relaxed during sitting, and so if you have a sedentary job, it can result in the tendon shortening. There are two main ways to tackle this, stretching and rolling. There are several stretches that you can use, either standing or lying down. For balance, you should always stretch on both sides, and go into and come out of stretches s-l-o-w-l-y - never bounce. One particularly effective yoga stretch (the pigeon) is shown here. From a position on your hands and knees, move the leg to be stretched across your body and then slide the other one backwards until you feel the stretch. You can get additional tension by bringing your head down to the floor and rolling towards the side with the straight leg.

You can roll out the iliotibial band with a solid foam roller, as illustrated. Regulate the amount of weight you put on the roller using your arms and the other foot, and roll back and forwards from knee to hip slowly about ten times. You will have a pretty good clue as to whether the trouble is coming from a tight iliotibial band, as this will be very uncomfortable until it loosens.

Stretch and roll at least once a day, and always when you are warm after a run. If none of this works, it might be time to go and see a doctor or physiotherapist for more specific advice.


What is the difference between walking and running? July 07 2015, 0 Comments

Weight transfer in walking does not exceed total body weight as the transition from one foot to the other involves a stage with both feet on the ground. With running, we are airborne for most of the time, so weight transfer includes the impact of landing which is typically two-and-a-half times body weight. The feet and legs have developed to absorb this impact, and cleverly to store energy from the landing for use in the next take-off.