Tag Archives: physical exercise

Exercise and mortality

5797534694_a36e9d8b0dExercising helps you to live longer, whatever the amount you are doing. If you exercise a little, your risk of an early death drops and if you exercise a lot, it drops even more. This is the conclusion of a study published on April 6th in the JAMA.

If you plot “benefits” against “dose” on a graph, most biological systems will show an inverted “U”. Take food for example: if you eat too little, you might die, but if you eat too much, you might also die. If you take a medicine, you have to take the right amount, as taking not enough will have no effect and taking too much is toxic.

Is the same true for exercise? Everybody agrees that you need a minimum of exercise to stay healthy, but some people believe that too much is bad for you. The recent cases of sudden deaths during competitions and the findings of heart rhythm disturbances in older endurance athletes have fuelled the debate.

To answer this question, Hannah Arem and her colleagues have looked at the mortality rates and physical activity levels of 661 137 men and women over 14.2 years.

Sure enough, they showed that having the recommended amount of exercise (a minimum of 150 min of moderate intensity, or 75 min of vigorous intensity endurance exercise per week) resulted in a 30% lower mortality risk compared to not exercising at all. However, any exercise is much better than none, as people who did less than the recommended amount already reduced their mortality risk by about 20%.

Working out more is even better, and exercising 2 to 3 times the recommended amount reduces your risk by 37%, while doing 3 to 5 times more leads to a 39% reduction.

The researchers noticed that those who exercise 10 times or more the recommended amount did not reduce their risk any further, but they could not observe any evidence of harm either.

Can I believe this?

This is very large study, which makes it trustworthy. Moreover, the results are the same for both genders and all BMI ranges.

On the other hand, it is based on questionnaires, and participants can easily over- or underestimate what they are doing or change their habits. However, most population studies about exercise and mortality suffer from these same limitations.

If Hannah Arem is right, concerning exercise, there cannot be too much of a good thing. Even though I have never met anybody running marathons or participating in triathlons for health reasons only, it is good to know we are not harming our bodies.

Keep going, but make sure that you avoid overtraining and injuries!

References

Arem H, Moore SC, Patel A et al. Leisure time physical activity and mortality: a detailed pooled analysis of the dose-response relationship. JAMA Intern Med 2015; DOI:10.1001/jamainternmed.2015.0533. (Abstract)

Photo

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Exercise and a family history of type 2 diabetes

© Kiankhoon | Dreamstime Stock Photos
© Kiankhoon | Dreamstime Stock Photos

Type 2 diabetes is more and more frequent in our Western world. It is probably the result of a complex and not- well-understood interaction of genes, lifestyle and obesity.

The disease starts with insulin resistance, which means that your tissues do not respond that well to stimulation by insulin. However, insulin is essential for the transfer of glucose from your blood into your tissues. As your tissues become resistant, you need more insulin to do the same job as before. If moreover the producing cells become dysfunctional, you will not be able to produce enough to keep your blood glucose levels normal and you will develop diabetes.

A family history of the disease is an important risk factor. Fortunately, you can lower your risk by exercising regularly. Working out will help you to normalise your glucose metabolism, as during exercise your muscles can take up glucose without insulin. It will also help you to keep your weight under control and reduce your risk of cardiovascular disease, which is diabetes’ major complication. Exercise is therefore a cornerstone of the prevention as well as of the treatment.

As exercise is so important for people at risk, the obvious question is: do people with and without a family history have different aptitudes for sport? To answer this, Antonio Bianco and his colleagues compared the aptitude for anaerobic performance of 33 elite athletes without a family history of type 2 diabetes with 13 elites with a family history.

The anaerobic metabolism is the pathway to produce energy without oxygen, as opposed to the aerobic metabolism. It is much quicker, but it is less economical than the aerobic metabolism, and your body will therefore use it for short, high intensity activities such as high intensity interval training and strength exercise.

The athletes performed squat jumps and a Wingate test*, which is the classical test to determine somebody’s peak anaerobic power.

As suspected, the athletes with a family history had a higher body mass than the others, but, surprisingly, their anaerobic performances were significantly better.

The majority of the studies showing the importance of regular workouts for diabetes used aerobic exercise. However, a mounting amount of evidence suggests that strength exercise is just as beneficial. If Bianco is right, his findings would be important for everybody who has a family history of type 2 diabetes, since it is likely that you will prefer an exercise discipline you are good at.

In other words: if you have a family history of type 2 diabetes, you might be better at sports that include shorter period of intense activity and/or power (e.g. most ball sports, gym work) than at endurance sports (e.g. distance running, walking). Maybe you would you therefore prefer them?

The most important thing is that you love your chosen form of exercise so much that you keep doing it!

*A Wingate test is performed on a specialised ergometer. After warming-up, the athlete starts pedalling as fast as possible. After three seconds the researcher adds a resistance corresponding to 75g/Kg of the athlete’s weight to the flywheel. The athlete continues to go as hard as possible for 30 seconds, and the researcher notes the peak power output.

Disclaimer: If you are new to exercising, please ask your doctor for advice first.This article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References and further reading:

A Bianco, F Pomara, M Raccuglia et al. The relationship between type 2 diabetes family history, body composition and blood basal glycemia in sedentary people. Acta Diabetol. 2014; 51(1): 79-84.

A Bianco, F Pomara, A Patti et al. The surprising influence of family history to type 2 diabetes on anaerobic performance of young male elite athletes. Springerplus. 2014; 3: 224. doi: 10.1186/2193-1801-3-224. eCollection 2014.

R Khardori, G T Griffing, B E Brenner et al. Type 2 Diabetes Mellitus. Medscape (Accessed on 5/10/2014).

R J Wood and E C O’Neill. Resistance training in type II diabetes mellitus: impact on areas of metabolic dysfunction in skeletal muscle and potential impact on bone. J Nutr Metab. 2012; doi:10.1155/2012/268197.  (Accessed on 5/10/2014).

Protein after resistance exercise

Do you need to take in extra protein after a strength exercise session and, if so, how much?
Scientists are still debating this question. It is an important one, even for endurance athletes, as we all need strength to practise our sport properly and to perform well. In the May edition of Sports Medicine, Stuart Philips from McMaster University has summarised what we know about this question.

© Milogu | Dreamstime Stock Photos
© Milogu | Dreamstime Stock Photos

Muscle proteins are in a constant turnover: some are broken down, and other are synthesised. As long as you making more muscle proteins than you are breaking down, your muscles will grow (hypertrophy) and you will get stronger, your performances will become better and, crucially for endurance sports, you will be able to maintain good form for longer and therefore reduce your risk of injury.

Resistance exercise will stimulate muscle protein synthesis for at least 24 to 48 hours. Proteins are made of amino acids, and having more amino acids in your blood will further enhance muscle protein synthesis. After a meal you tend therefore to make more proteins than you break down. The effects of eating and exercising reinforce each other, and this is why it is beneficial to have a protein rich drink or meal after your strength training session.

However, as exercise stimulates muscle synthesis for at least 24 hours, researchers such as Brad Schoenfeld and Alan Aragon believe that timing your meals is much less important than having enough protein in each of them. They think that supplements immediately after training are unnecessary as long as you are having a healthy diet containing enough protein. I have blogged about their opinions before.

There are 20 different amino acids, but our bodies can synthesise only 10 of them. The others are called the essential amino acids, as we have to get them from food. Unfortunately, we can only synthesise muscle proteins if all the essential amino acids are available, which means that we need a well balanced diet. One of them, leucine, is particularly important, as it triggers the synthesis. Foods that contain plenty of leucine, such as whey, are therefore more effective than others to build up muscles.

Working Up Sweat (ID: 74747)
© Vlad | Dreamstime Stock Photos

How much?

Having too much protein in your food does not help. The maximal effective amount is 0.25g protein/Kg body mass in younger people. Ageing and inactivity makes it harder to get the process of muscle synthesis started, and it is likely that we need more leucine and protein in our food as we get older. Older people may need up to 40g protein/ Kg body weight.

The rate at which the amount of amino acids rise in your blood is also important: a low level or an almost continuous delivery is much less effective than a bolus every three hours or so, as you would get from meals and snacks during a normal day.

Other components

– As yet, there is no evidence that other amino acids such glutamine or arginine, help to build up muscle.

– Carbohydrates are important to replenish your glycogen stores, but there are no reasons to believe that they influence muscle synthesis, as long as you have enough protein in your food.

In practice

Try to have at least three well balanced meals and/or snacks a day, each of which should contain sufficient protein, and schedule your workouts so that you finish before a meal. Do not eat too much protein either, as this is probably just wasteful.

As you get older, you will need more protein, especially more leucine. You will find a list of foods containing leucine by clicking here.

Never give up exercising, as inactivity and ageing are a bad combination for your muscles.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References

SM  Philips. A brief review of critical processes in exercise-induced muscular hypertrophy. Sports Med. 2014; 44 (1): 71-77.

BJ Schoenfeld,  A A Aragon and J W Krieger. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013; 10 (1): 53.

Alcohol and recovery from exercise

We all know that we should have some carbohydrates and proteins to recover faster after a hard workout, but what happens if at the same time we have a few drinks to celebrate the achievement? How will that affect the recovery?

© Dana Rothstein | Dreamstime Stock Photos
© Dana Rothstein | Dreamstime Stock Photos

In 2003, Louise Burke and her colleagues studied the effect of alcohol on the rebuilding of glycogen stores after an exhaustive bout of cycling. They noticed that alcohol slowed down the glycogen storage during the first 8 hours, but after 24 hours there was no difference anymore. This means that if the early phase of recovery was poor, there must have been a period of catching-up. They also showed that the main problem with drinking alcohol is that it makes it unlikely that you are taking in enough carbohydrates to rebuild your glycogen reserves, and, as you cannot make glycogen from alcohol, you could be losing out.

However, recovery is not only about glycogen, but also about rebuilding damaged muscle fibres. To do so you need to make new proteins, and taking in high quality protein soon after your workout can help your body to do so.

In a study published in PloSOne, Evelyn Parr and colleagues showed that drinking alcohol during your recovery hampers the protein synthesis. 8 men performed a workout comprising resistance, continuous and interval exercise. Immediately and 4 hours afterwards, they had a drink containing protein, protein with alcohol or carbohydrate with alcohol. The study was constructed as a cross-over design, which means that each volunteer performed the workout three times, using each time a different drink at the end. The researchers took muscle biopsies before the exercise, and 2 and 8 hours afterwards.
pone_0088384_g007
As you can see from this graph from Evelyn Parr’s article, alcohol impaired protein synthesis by 24%, even if the athlete had enough protein during his recovery. In real life, it is likely that the athlete would not take in proteins, and that the situation would be at best similar to having the alcohol and carbohydrate drink. That would mean 37% less protein synthesis.

The athletes in this study had about 12 standard units alcohol in their drinks. This sounds awful, but according to the researchers it corresponds to the mean amount used by team athletes during a drinking binge (!). We do not know yet what a safe amount of alcohol would be, or if that exists. We need therefore more research. Until we have that, it is better to be careful…

References:

Burke LM, Collier GR, Broad EM et al. Effect of alcohol intake on muscle glycogen storage after prolonged exercise. J Appl Physiol. 2003; 95: 983-990.

Parr EB, Camera D M, Areta J L et al. Alcohol ingestion impairs maximal post-exercise rates of myofibrillair protein synthesis following a single bout of concurrent training. PloSOne 2014; 9(2): e88384 doi: 10.1371/journal.pone.0088384.

Endurance exercise and your teeth

Dentists are more and more concerned about dental erosion, which is the loss of enamel (the hard tissue at the surface of your teeth) due to acids. As soon as the pH in your mouth reaches 5.5 the enamel starts to dissolve, which makes your teeth discolour, become more sensitive and finally erode away. The acidity can come from food or drinks, or from reflux of gastric contents. Bacteria can also produce acids, but this leads to caries.

Runner
Runner (Photo credit: jonny_w)

To protect your teeth, you need not only good hygiene, but also abundant saliva with a high pH and good buffering capacity to wash food rests away and neutralise the acidity.  Unfortunately exercise reduces the salivary flow rate, and scientists think this could be one of the reasons –or even the main reason- why athletes suffer more from tooth decay and erosion than other people.

Mai Tanabe and her colleagues have just published a study about the effects of drinks and food during exercise on the salivary flow rate, pH and buffering capacity. Ten volunteers exercised on bicycle ergometers for 20 minutes at 80% of their maximal heart rate, rested for five minutes and cycled again for 20 minutes. Each of them performed the test five times: 1) without any drinks or food, 2) using mineral water, 3) using mineral water with jellies, 4) using sport drinks and 5) using sport drinks with jellies. The researchers collected samples of their saliva before, during and after each exercise bout.

As expected, the salivary flow rate decreased significantly when the volunteers did not drink or eat anything during the workout. Drinking or eating restored it. The pH decreased when they used sport drinks, but remained unchanged when they had mineral water. The buffering capacity always declined, except when mineral water was used.

You can see the results here: http://www.jissn.com/content/10/1/49/figure/F1

The researchers therefore concluded that, from a purely dentist point of view, using mineral water with or without food was best. They admitted however, that you might have more important reasons to prefer sport drinks. If so, they advised to rinse your mouth as quickly as possible after your workout.

pH scale showing common substances
pH scale showing common substances (Photo credit: Wikipedia)

If the volunteers had to drink during a 2 x 20 minutes workout to keep their salivary flow and buffering capacity, I get the impression that we, distance runners, are a hopeless case! Drinking that often during a long run might put you at risk of overhydration and therefore hyponatremia, which can be fatal. I guess my best option is to keep visiting my dentist on a regular basis…

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References:

Aida Mulic, Anne Bjorg Tveit, Dag Songe et al. Dental erosive wear and salivary flow rate in physically active young adults. BMC Oral Health 2012; 12:8 doi: 10.1186/1472-6831-12-8.

Yan-Fang Ren. Dental erosion: etiology, diagnosis and prevention. Accessed on 25/02/2014

Mai Tanabe, Toshiyuki Takahashi, Kazuhiro Shimoyama et al. Effects of rehydration and food consumption on salivary flow, pH, and buffering capacity in young adult volunteers during ergometer exercise. J Int Soc Sports Nutr. 2013; 10:49 doi: 10.1186/1550-2783-10-49.

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Vitamin D and sport performances

If you feel that you are performing better in summer than in winter, you will be happy to hear that more and more scientific studies are backing you up. There is mounting evidence that vitamin D is important for muscle strength and recovery from intense exercise, and as this vitamin is synthesized in your skin thanks to the sun, it is likely that your levels are at their best in summer.

A Sunny Day in Cornwall
A Sunny Day in Cornwall (Photo credit: nosha)

In their latest study, Dr Tyler Barker and colleagues show that vitamin D supplementation enhances recovery immediately after intense exercise.  They asked 28 volunteers to perform 10 sets of 10 single leg jumps with 20 sec rest between the sets, and tested their strength  immediately before, just after, and 24h, 48h, 72h  and 168 h after the effort. 15 of the volunteers took vitamin D supplements and the others a placebo. As you could expect, everybody lost strength and experienced delayed muscle soreness after the jumps. The group who took supplements however, lost less strength immediately after the effort. From 24 hours later onwards, the strength deficit was the same in both groups.

This is important, because a bit more strength could be just enough to maintain good running form -or any other proper technique- at the end of a hard workout, and therefore reduce your risk of injuries. There is an association indeed between low vitamin D levels and injury rates in athletes, and this could be one the reasons why.

This study follows an earlier one (April 2013) by the same group showing that people with higher vitamin D blood levels experience less muscle strength loss after intense exercise than people with low levels.

What is vitamin D?

Vitamin D comes in different forms; the best known are vitamin D2 and vitamin D3. Some scientists think that vitamin D3 is the more potent form, while others think that they are equally effective.

As a matter of fact it is a hormone, produced when the skin is exposed to ultraviolet B radiation. We can also obtain it from food, but as our Western diets usually provide very little of it, most of it comes from sun exposure.

Vitamin D is transformed into calcidiol or 25-hydroxyvitamin D by the liver and can be stored to be used at a later date, for example in winter when we are unable to produce any because the sun is too low.

When needed, calcidiol is transformed into calcitriol or 1, 25-hydroxy vitamin D, which is the biologically active form. Calcitriol is not only  important for calcium absorption and bone strength, but it also alters the expression of genes affecting muscle protein synthesis, muscle size and strength, reaction time, coordination, balance, endurance, immunity, inflammation…. It is a very busy substance indeed, and crucial for general health as well as for athletic performances.

Vitamin D deficiency in our modern world

The benefits of vitamin D depend on how much you have: a blood level of less than 5 ng/ml leads to rickets in children and osteomalacia (“soft bones”) in adults. The elderly need 40ng/ml to reduce their risk of falls and fractures, and a low vitamin D status has been linked to infections and chronic illnesses such as diabetes, multiple sclerosis and cardiovascular diseases.

Scientists think that a blood level of 50 ng/ml is required for optimal health and sport performances. Higher levels do not seem to have additional benefits.

Vitamin D deficiency is defined as a calcidiol blood level of less than 30 ng/ml. Studies have shown that about 70% of the population is vitamin D deficient, and the problem is getting worse due to our modern lifestyle. Outdoor sports such as running should be an advantage, but research has shown that it does not make any difference, as most of us train in the mornings or evenings, when the sun is not strong enough to produce vitamin D.

Should I take supplements?

If you think you might be deficient, you should have your blood levels tested and decide with your doctor if and how much supplementation you need.

Experts are not sure what that they should advice for maintenance. If you are between 19 and 70 years old for example, the National Institutes of Health would recommend that you take 600 IU, but the Endocrine Society would recommend 1500- 2000 IU. We clearly need more research!

Vitamin D is a fat soluble substance your body cannot get rid of if you have too much of it. There is thus a risk of toxicity, even though that seems to be rare.

You could also try to make enough vitamin D in summer to get you through winter, as your body stores any excess produced.

UVB Vitamin D Solar Radiation Graph
UVB Vitamin D Solar Radiation Graph (Photo credit: Wikipedia)

However, even though you cannot get an overdose due to sun exposure, you can certainly get skin cancer! You therefore want to limit yourself to safe sunbathing, whereby you expose your skin (without sunscreen) to the midday sun for short periods avoiding reddening. As this is tricky (and dangerous if you get it wrong!) and might not be enough anyway, the best option is to take supplements, at least in winter.

Vitamin D is not a performance aid.

Even though vitamin D will help you to recover and protect you from fractures, it is unsure that it will make you faster. As yet, studies on athletes are inconclusive, even though many athletes report to perform better in summer and autumn than in winter.

You want an optimal level to be as healthy as possible, and excellent health will allow you to be the best runner you can be, which is totally different from doping indeed.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References

T Barker, V Henriksen, T Martins et all. Higher serum 25-hydroxyvitamin D concentrations associate with à faster recovery of skeletal muscle strength after muscular injury. Nutrients. 2013; 5(4): 1253-1275.

T Barker, E Schneider, B Dixon et all. Supplemental vitamin D enhances the recovery in peak isometric force shortly after intense exercise. Nutrition & Metabolism. 2013; 10: 69.

D Ogan and K Pritchett.Vitamin D and the athlete: risks, recommendations, and benefits. Nutrients. 2013; 5(6): 1856-1868.

F Shuler, M Wingate, G Hunter Moore et all. Sports health benefits of vitamin D. Sports Health. 2012; 4(6):496-501.

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Your ability to keep your core cool during exercise declines as you get older.

It is typically more difficult for older adults than for younger people to keep their core temperature within a normal range, which makes them more susceptible to heat related stress and illness.

A study published in PloSONE by Joanie Larose and colleagues showed that this decline in thermoregulation starts already as you reach 40, and worsens gradually as you get older. This is important if you are a master athlete planning his/her race calendar for 2014: you might want to plan your most important races when the weather is not too warm.

Participated Runners at 2007 ING Taipei Marath...

Joanie Larose and her colleagues examined 85 male volunteers between 20 and 70 years old during 15-min bouts of cycling separated by 15 min rest. The total duration of the test was two hours.

To calculate the amount of heat generated, the researchers measured the volume of O2 and CO2 expired, as these volumes correspond to the amount of fat and glycogen burned to obtain energy. As they knew from the cyclometer how much of that energy was used for exercise, they could easily calculate how much had been transformed into heat.

The researchers used direct calorimetry to measure the total heat loss. This means that they examined the air of the cylinder-like room in which the volunteer was cycling, as any change in the temperature and humidity was due to heat loss from the cyclist.

The difference between the heat generated and the heat dissipated is stored in the body, and results in thermal strain. Joanie Larose showed that from 40 years onwards, men gradually become less good at dissipating the excess heat.

This is important, since it could lead to an increased core temperature. As this is dangerous for your health, your unconscious brain will do what it can to keep your core temperature within the normal range.  During exercise, it will therefore slow you down by making you feel tired and reducing the amount of muscle fibres you can use.

Consequently, master athletes will find it more difficult to compete at their best in warm conditions. It is thus a good idea to plan your A races during cooler periods of the year.

East of Ireland Marathon Series 2013 - Race 7 ...

This study has been performed on men, and we cannot assume that the same happens to women. We just do not know. Most studies show that women tend to sweat less than men, but it is no clear yet how this affects their thermoregulation.  We need more research.

References:

Jay O, Kenny GP. The determination of changes in body heat content during exercise using calorimetry and thermometry. J Hum Environ Syst. 2006; 10: 19–29. doi: 10.1618/jhes.10.19.

Larose J, Boulay P, Sigal RJ, Wright HE, Kenny GP. Age-Related Decrements in Heat Dissipation during Physical Activity Occur as Early as the Age of 40. PLoS ONE. 2013; 8(12): e83148. doi:10.1371/journal.pone.0083148.

Are ice baths good or bad for you?

Even though ice baths are popular between athletes, scientists are still not sure whether they are useful and safe. In a study published in Extreme Physiology & Medicine, Gillian White and Greg Wells reviewed the studies about their immediate effects on recovery. As the long-term and possible negative side-effects have not been properly evaluated, they could not comment on them, even though they might be important.

English: Running on the Dam at Tringford Reser...

How does a bout of intense exercise affect your muscles?

Metabolic stress

A hard workout requires a lot of energy production and creates heat, which lead to an increase in reactive oxygen species (ROS). ROS are highly reactive chemicals that can destroy proteins en lipids. They damage the cell membranes and the coupling between nerve cells and muscle fibres. The latter makes contractions more difficult and less efficient, while the former makes the muscle fibre more permeable to water and leads therefore to oedema of the cell. Oedema compresses capillaries, and makes it more difficult to deliver oxygen correctly and to take waste products away. It also makes you feel sore.

To repair the damaged muscle fibres and to take the debris away, your body starts an inflammatory reaction. Even though you cannot recover without it, it is often too strong and can lead to further damage.

Mechanical stress

Intense or unaccustomed exercise can also lead to mechanical stress, especially when the muscular contractions are eccentric (contracting while the muscle is lengthening, as for example the quadriceps muscle does when you come down the stairs). This disrupts the membranes, which interferes with contractions, makes the cells more permeable and leads to oedema. Micro trauma can lead to muscle spasm.

Here again, you need an inflammatory reaction to repair the muscles, but it might start off by creating further damage.

How could an ice bath help you?

After exercise, muscles have an increased energy demand as they try to repair themselves and to replace energy stores. Cooling will slow their metabolism down, and therefore generate less ROS. It will decrease the inflammatory reaction and the muscle spasm, and as it reduces the blood flow, it also limits the oedema.

It cannot do anything about the effects of mechanical stress and disruption of the muscle fibres, but as muscle soreness is often due to a combination of mechanical and metabolic stress, it can help. How useful it is will therefore depend on the kind of exercise you have done.

Ice has an analgesic effect, but this can be confusing, since your muscles might not have recovered even though the soreness has disappeared.

Possible long-term effects

ROS are essential to allow your body to increase its anti-oxidant defence mechanism. A stronger defence mechanism will allow you to withstand more ROS production during your next work-out. To destroy all of them is thus harmful. Your body has to learn to regulate them, and this is part of the training effect of a workout.

Without an effective inflammatory reaction you cannot properly repair your muscles. You need it to replace the dead and damaged muscle fibres by stronger ones, and to become a better athlete in the process.

As far as I know, there are no studies examining the long term effects of ice baths, but sport scientists are worried indeed that taking too many of them could reduce the benefits you get from your hard work. The usual advice is therefore only to use an ice bath if you are participating in multi-day events or if you have so many races planned that you cannot recover quickly enough otherwise.

English: Weightlifter Karyn Marshall in an ice...
English: Weightlifter Karyn Marshall in an ice-bath as part of athletic training in July 2011. (Photo credit: Wikipedia)

Dangers

Even if you are a very fit athlete, taking a cold bath is a shock to your body. You could hyperventilate, faint or develop heart rhythm disturbances. As yet, no studies have looked into this problem, and therefore we do not know if it is a real risk. Worse, as it is not clear how helpful ice baths really are, we do not know what the risk/benefit ratio is.

References:

C Bleakley, S McDonough, E Gardner et al. Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise. The Cochrane Library 2012 doi: 10.1002/14651858.CD008262.pub2; accessed on 15/09/2013.

G E White and G Wells. Cold-water immersion and other forms of cryotherapy: physiological changes potentially affecting recovery from high-intensity exercise. Extreme Physiology & Exercise. 2013; 2:26 doi:10.1186/2046-7648-2-26; accessed on 15/09/2013.

Skeletal muscle damage and repair. Ed: P. M Tiidus; Human Kinetics 2007.

Endurance exercise can increase your chances of a long life by preserving the length of your telomeres.

Joshua Denham and colleagues have published a study in PloS One showing that ultra-marathon running can help you to live longer by protecting your chromosomes.

Telomeres are DNA proteins that cap the end of your chromosomes to protect them. They become shorter with each cell division unless they are restored by an enzyme called telomerase. Unfortunately, most of our cells do not have enough telomerase to restore them completely, and eventually they become so short that the cell cannot divide anymore, becomes dysfunctional and dies.Telomere

Shorter telomeres are associated with numerous diseases and a higher mortality rate.

Scientists therefore consider their length as a measure of your biological age. It is determined by your genes (some of us are born with longer ones) and by the rate at which they are shortening.

Several studies have shown that a healthy lifestyle is associated with longer telomeres, probably by stimulating telomerase.

Physical exercise

Most scientists agree that physical exercise is good for your telomeres, but they do not know what the optimal or safe amount is.

A study by Ludlow has suggested that very heavy physical activity is associated with shorter telomere length, just as a sedentary lifestyle is, while life-long moderate physical activity is linked to longer telomeres. This would mean that extreme endurance exercise is bad for you.

The telomeres of ultra-marathon runners

Joshua Denham and his colleagues examined the telomeres of 67 ultra-marathon runners and compared them with those of 56 healthy men of the same age. They noticed that the runners had significantly longer ones. Biologically the runners would be about 16.2 years younger than the more sedentary men, and the researchers concluded that ultra-endurance exercise can slow the aging of your cells down.

They also showed that this was independent of the traditional risk factors such as cholesterol, triglycerides and blood pressure.

2007 Soochow International 24h Ultra-Marathon:...

Can I believe this?

Denham’s study is stronger than previous ones because it is bigger, the age range of the participants is larger and the runners perform a higher amount of aerobic exercise.

Just as the other ones, it is an observational study, which means that the scientists looked for an association between two findings, in this case endurance running and telomere length. It does not mean that one leads to the other, even though other studies have shown that endurance athletes live longer than the general population. It is possible that people born with longer telomeres are for some reason more likely to become endurance athletes. Based on these studies alone, there is no way that you can exclude this possibility.

Joshua Denham did not have any information about the diet and psychological stress of the participants. It has been proven that both factors influence telomere length, and you could easily imagine that ultra-marathon runners are much stricter with their nutrition than more sedentary people.

We obviously need more research to come to a definitive conclusion, but the difference between the ultra-runners and the others is so large that it has to make you think!

References:

J Denham, C Nelson, B O’Brien et al. Longer leukocyte telomeres are associated with ultra-endurance exercise independent of cardiovascular risk factors. PloS One. 2013; 8(7): e69377 (accessed: 30/08/2013).

A Ludlow, J B Zimmerman, S Witkowski et al. Relationship between physical activity level, telomere length, and telomerase activity. Med Sci Sports Exerc. 2008; 40: 1764-1771.

M A Shammas. Telomeres, lifestyle, cancer, and aging. Curr Opin Clin Nutr Metab Care. 2011; 14(1): 28-34.

Why do we run?

Runner on Blue Trail

Have you ever wondered why you want to go for a run? Why do we have that urge, even if it is hot and humid or cold and wet, and why do we feel so miserable when we cannot go out? No other sport is so addictive…

Traditionally people thought that humans were very poor runners, as we are never able to catch another animal. However, since the beginning of this century, this has changed. Scientists such as Daniel Liebermann, Dennis Bramble and David Carrier have shown that even though we are not good at sprinting, we are actually very good endurance runners. We cannot run as quickly over short distances as for example big cats, because as we run on two legs instead of four, we cannot gallop and we therefore always trot.

No animal can gallop over long distances, and endurance running is always done by trotting. Compared to other animals of our weight, we are rather good at it: recreational runners tend to trot at 3.2m/s to 4.2 m/s (11 a 15 km/h), while most animals of about 65 kg trot at approximately 2.8 m/s (10km/h).

We are also able to keep going for much longer than most animals: many of us run several kilometres a day and participate in marathons, while wolves travel on average only 14 km/day and hyenas 19 km.

Made to run

Daniel Liebermann showed that we are made for endurance running: we have long tendons, such as the Achilles tendon and iliotibial tract, and plantar arches in our feet which act like springs and save energy during running. Thanks to our butt muscles we can stabilize our bodies, and we have a special ligament at the back of our neck (the nuchal ligament) to keep our heads still. Our forearms are light and short, and therefore easy to swing.

The most important adaptation to long distance running is probably our ability to sweat all over our bodies. It allows us to get rid of excess heat in a much more effective way than by panting. Moreover, we do not have a coat, which makes it even easier to keep cool.

As all these adaptations came along when our species evolved, about 2 million years ago, we can conclude that we are made to run. However, it does not explain why we run.

Why did our forefathers have to run?

It is unlikely that our forefathers ran to escape from meat-eating animals, as they could not gallop and could therefore never be fast enough over a short distance.

David Carrier thinks that they ran to hunt: during the heat of the day, they chased their prey relentlessly until it collapsed. The prey would have galloped to get away, but as the hunters kept coming, it had to flee again even though its core temperature was still high. After several hours of pursuit, it would simply die from heat exhaustion.

Remember that humans do not have big claws or teeth to kill prey, and as our forefathers did not have good weapons it was easier if the animal died naturally.
They might also have taken advantage of kills made by other animals. Getting there quickly, before the hyenas for example, would have been very important.

Carrier thinks that the whole family hunted together, leaving the children in a safe place with one adult, just as wolves and wild dogs still do.

This technique is called persistence hunting. It is very difficult (impossible) to prove that it was indeed what our forefathers did, but the Bushmen, the Tarahumara Indians and the Aborigines occasionally still hunt this way.

Humans took up farming only about 10,000 years ago. Compared to the 2 million years of evolution as a species, this is a very short time and we still have bodies adapted to run over the savannah.

Would it be possible that we are unconsciously trying to do what we are originally made for?

Runner’s high

Running over the savannah was dangerous. Not only could you get injured or killed, you could also spend a lot of energy without obtaining any food, and starve. Even so, it must have been the best way to obtain high quality protein, and to make sure our forefathers kept taking the risks, evolution developed runner’s high.
Runner’s high is a feeling of general well-being that takes away the pain and suffering of hard exercise. Nobody experiences it during every run, and some people never do.
Scientists believe it is mediated by several chemicals, of which the endocannabinoids are the most important ones. Endocannabinoids are substances produced by our bodies that act on our nervous system in the same way as marijuana.

To show that runner’s high is an important evolutionary tool, David Raichlen and his team measured the endocannabinoid levels in humans, dogs and ferrets after a 30’ run. Wild dogs run to capture prey, but ferrets do not as they tend to ambush it. Sure enough, the researchers noticed a rise in endocannabinoid levels in humans and in dogs but not in ferrets, and concluded that runner’s high is typical for animals that hunt by running.

Does that mean that we run in the hope to get a high?

Icon Runners MillaSagradaFamilia2005

Your body is the only equipment you have

Running is one of the rare sports we do not need any equipment for, and in a world where about everything is done with the help of a machine or a tool, this is very special indeed. It is fascinating to explore what we can do “on our own”.

It also means that we are solely responsible for all our successes (and all our disappointments).

In his book “Why we run: a story of obsession”, Robin Harvie therefore concludes that running allows him to lead a more authentic life. I am sure we can all agree with that.

What does running mean for you, and how has it changed your life?

References:
D Bramble and D Lieberman. Endurance running and the evolution of homo. Nature. 2004; 432: 345-352.
D Carrier. The energetic paradox of human running and hominid evolution. Current Anthropology. 1984; 25(4): 483-495.
Robin Harvie. Why we run: a story of obsession. John Murray Publishers 2011.
D Raichlen, A Foster, G Gerdeman et al. Wired to run: exercise-induced endocannabinoid signalling in humans and cursorial mammals with implications for the runner’s high. J exp Biol. 2012; 215: 1331-1336.