Tag Archives: exercise

Cramps

A new study suggests that cramps during exercise have nothing to do with electrolytes or dehydration, but are simply due to muscle fatigue.8479719962_3208ac3c1e

For decades we have been told that cramps during long runs are due to dehydration and loss of electrolytes. It is tempting to think so indeed, as patients with disturbed electrolytes due to illness suffer from cramps. However, these patients are usually severely ill and have cramps all over their bodies. Runners on the other hand, typically have them in the working muscles and often only later in the race. Moreover, they might be tired but they are not ill!

Scientists now suspect that cramps in runners (or in any athlete) might be something different. Indeed, there is more and more evidence that cramps are due to muscular fatigue, and the latest study by Martin Hoffman and Kristin Stuempfle suggests this as well.

They studied 280 runners during a 161 km ultra-marathon by measuring their body weight before, during and after the race, and they determined their sodium and CK (= a measure of muscular damage) levels by a blood sample after the race. The runners also completed a questionnaire about cramping, “near” cramping (= controllable, not full blown), drinking strategies and the use of electrolyte supplements.

14% of the participants reported cramping, and 28% near cramping. There was no difference in changes in bodyweight or sodium levels between those suffering from cramping or near cramping and the others. Those who cramped or near cramped however, showed higher CK blood concentrations and were more likely to have suffered from them in the past.

The researchers concluded that cramping was associated with muscle damage, which confirms other studies suggesting that it is due to fatigue.

This is important for all of us, because if they are right, there is no need to take electrolyte supplements. It could then be more beneficial to review our training, build up our muscle strength and see if our technique needs improving.

References:

KW Braulick, KC Miller, JM Albrecht et al. Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency. Br J Sports Med. 2013; 47(11): 710-4.

MD Hoffman and KJ Stuempfle. Muscle cramping during a 161 km ultra-marathon: comparison of characteristics of those with and without cramping. Sports Med Open. 2015; 1 (1):8.

MP Schwellnus, EW Denman and TD Noakes. Aetiology of skeletal muscle “cramps” during exercise: a novel hypothesis. J Sports Sci. 1997; 15(3):277-85.

MP Schwellnus. Cause of exercise associated muscle cramps (EAMC) — altered neuromuscular control, dehydration or electrolyte depletion? Br J Sports Med. 2009; 43(6):401-8.

 

Picture: photo credit: <ahref=”http://www.flickr.com/photos/25874444@N00/8479719962″>The Donadea 50KM Ultramarathon Race 2013</a> via <a href=”http://photopin.com”>photopin</a&gt; <a href=”https://creativecommons.org/licenses/by-sa/2.0/”>(license)</a&gt;

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A cold drink to exercise in the heat?

Could consuming cold drinks or ice slush during workouts in the heat help you to perform better? Scientists have been wondering this for many years.

Theoretically it makes sense: as your brain’s main objective is to keep you safe, it will force you to slow down or even stop if it presumes that your core temperature could increase to dangerous levels before the end of the workout. Anything that helps you to keep your core temperature down is thus beneficial, and as cold drinks could act as a heat sink they could be helpful indeed. Scientific studies however, have been inconclusive.

© Dnally | Dreamstime Stock Photos
© Dnally | Dreamstime Stock Photos

Florence Riera and her colleagues have just published the latest study about this problem in PlosOne. They compared the effects of a cold (3 C), ice slush (-1 C) or neutral drink (23 C) with or without menthol flavouring on the performances of 12 trained male cyclists in hot and humid conditions.

The cyclists were randomly assigned a beverage and performed a 20 km time trial in the lab, which means that each of them did the test 6 times (once with each beverage). The performance was better using ice slush whatever the aroma, and better with menthol whatever the temperature. Ice slush or cold water with menthol flavouring was therefore the best.

The researchers concluded that a cold or ice slush drink interferes with the rise in core temperature, allowing you to exercise harder without – or with a smaller- increase in core temperature. 

Menthol usually provokes a sensation of freshness, it is a bit stimulating and it improves the airflow (that is why you use menthol lozenges when you have a cold), but exactly how it works is unknown.

Drinking ice slush is probably possible when you are cycling on a turbo trainer or in the gym, but what can you do if you are a road cyclist? You could try to cool down your core in advance, and researchers have shown that ice vests or cool water baths are helpful indeed.

Pre-cooling techniques are usually unavailable for recreational athletes, but cold drinks can easily be obtained before the start of any event. Christopher Byrne and his colleagues therefore wanted to find out if you could pre-cool yourself with cold drinks.

Seven male cyclists ingested 900 ml cold (2 C) or neutral (37 C) water over 35 minutes before cycling as many kilometres as possible for 30 minutes in a lab. When the athletes drank cold water they cycled 2.8% further and their core temperature (as estimated by rectal temperature measurements) was lower at the end of the test. They felt really cold before starting off though, and one of them was even shivering. Most of them needed to urinate before the exercise. Probably not a very pleasant experience….

© Denise Scott Jackson | Dreamstime Stock Photos
© Denise Scott Jackson | Dreamstime Stock Photos

I wonder if this kind of pre-cooling is possible for runners, as such a large amount of fluid is likely to create gastro-intestinal discomfort? I guess that the only thing runners can do is to get acclimatised and to accept that we will be slower…Or do you have a better idea?

References

C Byrne, C Owen, A Cosnefroy et al. Self-paced exercise performance in the heat after pre-exercise cold-fluid ingestion. J Athl Train. 2011; 46(6): 592-599.

 F Riera, TT Trong, S Sinnapath et al. Physical and perceptual cooling with beverages to increase cycle performance in a tropical climate. PLoSONE 9(8): e103718. doi:10.1371/journal.pone. 0103718. (Accessed 09/08/2014).

R Tucker. The anticipatory regulation of performance: the physiological basis for pacing strategies and the development of a perception-based model for exercise performance. Br J Sports Med 2009; 43: 392-400.

 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.

Active kids reduce their risk of cardiovascular disease later in life

We know that atherosclerosis begins in childhood, but are children with an unhealthy lifestyle invariably going to suffer from atherosclerosis as they get older? Nobody is sure…

© Alexk | Dreamstime Stock Photos
© Alexk | Dreamstime Stock Photos

A Finnish group of researchers has therefore started to follow-up risk factors in young people. The first survey was done in 1980, when they examined 3596 youngsters between 3 and 18 year old. The same group was then re-examined in 1983, 1986, 2001 and 2007. The researchers measured the usual risk factors such BMI, blood lipids and blood pressure, and asked about their diet and exercise habits.

In 2001 and 2007, the researchers also determined the wall thickness and elasticity of the youngsters’ arteries. Wall thickness and elasticity (or stiffness) are two different signs of vascular aging, and both of them are probably very early stages of the disease. As yet, we do not know which one is more important.

By comparing the evolution of arterial wall thickness and elasticity with risk factors, we can determine if a child’s lifestyle influences its risk of cardiovascular disease later in life.

Elasticity

In their latest article (April 2014) the Finnish group published their findings concerning the association of exercise in childhood or adolescence and the elasticity of the carotid arteries 21 years later. The carotid arteries are situated in the front of your neck and supply your head and neck with oxygenated blood. They are rather important, as your risk of stroke increases if they narrow due to atherosclerosis!

They noticed that exercise in children and adolescents was associated with an increased arterial elasticity in 30 to 34 year old adults. This was independent of other factors such as BMI, blood lipids or insulin levels. They concluded that it pays off to be an active kid.

Vigorous exercise

This confirms a similar study published in 2010 by Roel van de Laar and his colleagues. They followed 600 boys and girls during 24 years, and noticed that adolescent and young adults involved in vigorous physical exercise had more elastic arteries at the age of 36 than those who performed only easy or moderate workouts.

They also noticed that those who kept exercising vigorously in adulthood had a much better elasticity than those who slowed down. The difference in elasticity went hand in hand with other risk factors such as cholesterol levels, resting heart rate, cardio respiratory fitness…

They concluded that we should keep exercising vigorously as we get older to keep our arteries healthy.

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

Arterial thickness

The Finnish group also compared the classical risk factors (exercise, diet, BMI, cholesterol, blood pressure blood glucose levels…) with the thickness of the arterial wall. They noticed that childhood risk factors became non-significant compared to adult ones, except for physical activity and fruit consumption.

This means that if somebody has unfavourable cholesterol levels or is obese as a child, but corrects this as an adult, the arterial wall thickness is not worse than that of somebody who was not obese or did not have bad cholesterol levels as a child.

For fruit consumption and physical exercise however, this seems not to be true. Eating a healthy diet and exercising regularly as a child is thus important for your arteries.

What does this mean for me?

If you are lucky enough to have exercised and eaten a healthy diet as a child, your arteries are likely to be healthy. This is not a reason to stop taking care of yourself, as Roel van de Laar’s study shows that we should continue exercising vigorously.

Vigorous exercise is of course different for each of us. What feels like running hard for me is maybe only a jog for you. Only you can know what vigorous exercise is for you. Don’t forget either that nobody exercises vigorously every day. If you are in doubt, you should contact a health or fitness professional.

Even though exercising as an adult might not totally reverse the lack of exercise as a youngster, it will help you to keep all other risk factors under control. Moreover, your health depends on much more than the thickness or elasticity of your arterial walls. Exercise will reduce your risk of many diseases, such as diabetes, Alzheimer and some cancers. It is therefore never too late to start!

The Finnish study is ongoing, and that is a good thing as there are plenty of questions left. For example: what happens to those of us who are active as a child and adolescent,  abandon sport to raise a family, and start training again when life becomes less busy?

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:

Juonala M, Viikaril J S A, Kahonen M et al. Life-time risk factors and progression of carotid atherosclerosis in young adults: the cardiovascular risk in young Finns study. Eur Heart J 2010; 31(14): 1745-1751.

Palve KS, Pahkala K, Magnussen CG et al. Association of physical activity in childhood and early adulthood with carotid artery elasticity 21 years later: the cardiovascular risk in young Finns study. J Am. Heart Assoc. 2014; 3(2): e000594.  doi: 10.1161/JAHA.113.000594.

Van de Laar RJ, Ferreira I, van Mechelen W et al. Lifetime vigorous but not light-to-moderate habitual physical activity impacts favorably on carotid stiffness in young adults: the Amsterdam growth and health longitudinal study. Hypertension 2010; 55(1): 33-39.

Extra chocolate to help you recover even better?

Chocolate milk is a popular recovery drink and many studies have shown it is just as good as specially designed, commercial drinks.
It contains carbohydrates and proteins in a 4:1 ratio, which is widely considered the best for recovery. Milk contains casein and whey proteins, resulting in sustained high blood levels of amino acids, and plenty of branched chain amino acids, which are essential for rebuilding your muscles. It also has a high concentration of electrolytes, to replace those you have lost through sweating.

English: A glass of chocolate milk.
Moreover, cocoa contains flavanols, which are antioxidants. Oxidants are natural by-products of your metabolism, and during exercise you produce more of them. They are highly reactive substances and even though they are essential for normal cell function, they can damage cells and therefore further aggravate muscle pain after intense exercise.

To keep them under control your body uses antioxidants, some of which are produced by your cells, and others are obtained from your diet.
You could therefore conclude that having extra chocolate after a hard workout would help you to recover. But does it?

A large amount of the flavanols is lost as cocoa is processed. To find out if flavanols are really helpful, you should thus compare the effects of ordinary chocolate milk with those of chocolate milk containing extra flavanols.

Kately Peschek and her colleagues did just that, and in January 2014 they published their results in Nutrients.
They asked 8 well-trained endurance athletes to run downhill for 30’, -creating delayed onset muscular pain-, and then gave them chocolate milk or chocolate milk + flavanol rich cocoa. They measured their plasma CK levels (a marker of muscle damage), muscle tenderness, self perceived soreness and force, and made the volunteers run a 5 km time-trial. 3 weeks later the same athletes did it all over again, using the other beverage.

Unfortunately, they could not notice any difference… (That is bad news for all chocolate lovers!)

The researchers wondered if the athletes should have taken cocoa before the exercise to see an effect. On the other hand, there is evidence that milk slows down the absorption of flavanols. It would be interesting to see if taking extra chocolate without any milk is helpful.

Note that taking antioxidants as supplements is not a good idea. Researchers now agree that this is useless and can be even harmful.

Chocolate for your health
Chocolate is good for you, unless you consume too much of it. It contains more flavanols than red wine or tea. It also has caffeine and theobromine, which are central nervous system stimulants, and minerals such as potassium, phosphorus, cupper, iron…

This is 72% cacao organic dark chocolate from ...
Epidemiological studies have shown that chocolate can help to reduce blood pressure, dilate blood vessels, lower stress levels and make cells more sensitive to insulin. Many researchers believe it can protect you from cardiovascular disease.

You have to be careful however, as it contains a lot of calories and can therefore make you gain weight. If you want to consume chocolate on a regular basis, you will have to reduce the calories you get from other foods. Do not cut down on the healthy ones though, as then you would do more harm than good!

You have to choose flavanol rich chocolate, which is difficult to do as this is usually not mentioned on the packaging. You can increase your chances by taking the dark and bitter forms. Do not forget to check the labels to make sure they do not contain transfats.

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:

Latif R. Chocolate/cocoa and human health: a review. Neth J Med 2013; 71 (2): 63-68.

Peschek K, Pritchett R, Bergman E and Pritchett K. The effects of acute post exercise consumption of two cocoa-based beverages with varying flavanol content on indices of muscle recovery following downhill treadmill running. Nutrients. 2014; 6(1): 50-62.

Roy B. Milk: the new sports drink? A review. J Int Soc Sports Nutr. 2008; 5:15.

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What is the best exercise to get back in shape?

Exercise is a well established tool to keep healthy. The American College of Sports Medicine recommends a minimum of 150 min endurance exercise a week and 20 min of resistance exercise two to three times a week (click here for more details).This is only a minimum indeed and if you are reading this, it is likely that you want to do more to improve your health further. Whatever your goals are, it is important to determine which kind of exercise is the most effective, as we are all short of time.

Cyber Soldier shows prowess in endurance events

Several researchers have studied how and if endurance training, resistance exercise or a combination of both affect health parameters such as body weight, waist circumference, lean body mass, blood lipids, fitness… Lukas Schwingshackl and his colleagues have reviewed these studies to determine which modality would be the most effective, and in December 2013 they published their conclusions in PLoSONE.

Results

The main result was that endurance exercise was the most effective to reduce body weight, waist circumference and fat mass, and to improve fitness (as measured by VO2max). Resistance exercise however, was better to increase lean body mass. There were no significant differences in the improvement of the blood lipids between the exercise modalities.

Researchers use waist circumference to estimate visceral fat, which is an important risk factor for cardiovascular disease. A reduction in waist circumference, suggesting a decrease in visceral fat, is thus an important result. An increase in VO2max is associated with reduced all-cause mortality and a lower risk of cardiovascular risk. Endurance training can thus really improve your life!

Resistance training leads to an increase in lean body mass, thus in muscle mass and strength. This counteracts the loss you normally experience due to aging. This is important, as the tasks of daily life do not become lighter because you are getting older. If you want to stay active and independent in old age you have to maintain your strength.

English: Participant being guided through resi...

Lukas Schwingshackl and his colleagues concluded from their review that combining endurance with resistance training allows us to reap the benefits of both modalities, and is therefore the most promising regimen. However, they admit that this increases the time you spend exercising. In two of the reports they examined, the time even doubled.

If you don’t have time

In 2011, Criz Slentz compared the effects of endurance training, resistance exercise and a combination of both on 249 volunteers, taking great care that everybody was spending the same amount of calories while exercising. He also concluded that endurance training was more effective than resistance exercise to reduce visceral fat and to improve fitness, but he could not notice a difference between the effects of endurance and combination endurance/resistance training. As resistance training is more time consuming, he advised to keep to endurance training.

Can I believe the review?

Lukas Schwingshackl’s review is a meta-analysis, which means that they analysed, evaluated and compared studies done by other researchers in order to come to a conclusion. This saves people like you and me a lot of time and effort!

On the other hand, we have to trust that they have excluded all the bad studies and kept the good ones. In theory, there is always a danger that reviewers cherry-pick the studies they like.

Moreover, reviewers can only analyse studies that have been published. As nobody likes to read negative results or no-reports, only the positive ones get published. It is therefore always possible that a review is biased because of a lack of data. This is called publication bias and is very hard to avoid.

What does it mean for me?

As yet, we can conclude that a training regimen combining endurance and resistance exercise is the best option. If you are short of time however, you should stick to endurance training.

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:

Schwingshackl L, Dias S, Strasser B et al. Impact of Different Training Modalities on Anthropometric and Metabolic Characteristics in Overweight/Obese Subjects: A Systematic Review and Network Meta-Analysis. PLoS ONE. 2013; 8(12): e82853. doi:10.1371/journal.pone.0082853.

Slentz C, Bateman L, Willis L et al. Effects of aerobic vs resistance training on visceral and liver fat stores, liver enzymes, and insulin resistance by HOMA in overweight adults from STRRIDE AT/RT. American Journal of Physiology – Endocrinology and Metabolism. 2011; 301: E1033-E1039. doi: 10.1152/ajpendo.00291.2011.

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What are tendinopathies?

People running at the 2007 20 kilometer road r...

Tendinopathy is the scientific name for chronic tendon disorder. In this post we will explain the basic science behind tendinopathies, and why they are so difficult to treat. As always, an understanding of what is happening will help you to manage them better.

Tendinopathies are extremely common, especially between athletic people. They are characterised by pain during activity, local tenderness and loss of strength and movement. As they can stop a sporting career in its tracks, or force you to change sports, it is important that you take them seriously. They can occur in almost any tendon. Examples include chronic Achilles tendinitis and patellar tendinitis (jumper’s knee), but as inflammation is not the main problem, tendinitis is a misnomer.

The right amount of exercise

Tendons consist mainly of collagen bundles and tenocytes. The latter are cells that respond to mechanical loading by forming new collagen fibres to replace the old and injured ones. To keep your tendons healthy you have therefore to load your tendons enough to stimulate your tenocytes. This explains why adequate training makes your tendons stronger, and why the right amount of mechanical loading will improve the healing of acute tendon injuries.

Overuse and micro trauma

Scientists are still struggling to understand what exactly happens when a tendinopathy develops. As yet, most of them think that due to overuse and micro trauma the tenocytes lose their ability to produce quality collagen fibres. The new fibres are inadequate, disorganised and slack, and loading them mechanically does not stimulate the tenocytes anymore. In a further attempt to repair the tendon, new blood vessels are formed and infiltrate the lesion. Nerves typically accompany these new vessels, and only now the tendon becomes painful.

The whole process corresponds therefore to a failed healing response and degeneration, and pain only develops at the end. Furthermore, as a tendon can degenerate without pain, it can rupture without any warning signs.

How can I treat a tendinopathy?

Patients are offered many different treatments, but, except for eccentric exercise training, there is not much evidence for any of them. That does not mean that they are useless, it only means that we need more research.

Non steroidal anti-inflammatory drugs (NSAID) might reduce the pain a little in the beginning, but they are not helpful and are therefore best avoided.

Eccentric exercise treatment

In 1998, Alfredson and colleagues introduced eccentric exercise training to treat chronic Achilles tendinitis, and since then the technique has been used for other tendinopathies as well.

An eccentric contraction is an action whereby the muscle contracts and lengthens at the same time. If you stand with the ball of your foot on a stair and lower your heel, you contract your calf muscles eccentrically, and when you come down the stairs you do the same with your quadriceps muscles.The Achilles' tendon. PD image from Gray's Ana...

Alfredson showed that performing eccentric exercises on a daily basis for 12 weeks reduced the pain of chronic mid-tendon Achilles tendinopathy in 90% of the cases. The patients performed sets of 15 repetitions twice a day, building up to 180 repetitions a day. When the movement became pain free, they started doing the exercises carrying weights in a backpack. Alfredson advised to work trough pain unless it was severe, and to use his regimen together with other physiotherapy techniques, such as relative rest, massage, ultrasound… After 12 weeks, most of his patients could return to their previous activity levels, even though they had to continue with a maintenance treatment.

It is not completely clear how eccentric exercise training works. Researchers have noticed that during eccentric contractions the forces in the tendon tend to fluctuate. These fluctuations could be an important stimulus for the tenocytes to produce collagen and to remodel the tendon. If this is correct, the number of contractions and the speed at which you perform them will be more important than adding weight.

Will I get rid of it?

After successful treatment, most people continue to feel some mild pain, even though they can return to their previous sport activities.

Even if the pain has completely gone, you will be at a high risk of recurrence, as the tendon can still be degenerated even if it is not painful anymore. You will therefore have to “manage” your tendon, by making sure that you give it enough time to recover after hard workouts, and that you keep doing maintenance exercises. You will continue to improve over time.

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

References:

H Alfredson and J Cook. A treatment algorithm for managing Achilles tendinopathy: new treatment options. Br J Sports Med. 2007; 41(4): 211–216.

K Gravare Sibernagel, R Thomee, B Erikson and J Karlsson.  Full symptomatic recovery does not ensure full recovery of muscle‐tendon function in patients with Achilles tendinopathy. Br J Sports Med. 2007; 41(4): 276–280.

J  Rees, G Lichtwark, R Wolman and A Wilson. The mechanism for efficacy of eccentric loading in Achilles tendon injury; an in vivo study in humans. Rheumatology. 2008; 47 (10): 1493-1497.

A Scott, E Huisman and K Khan. Conservative treatment of chronic Achilles tendinopathy. CMAJ. 2011; 183(10): 1159-1165.

Y Xu and G Murell. The basic science of tendinopathy. Clin Orthop Relat Res. 2008; 466(7): 1528-1538.

Humans and dogs can get a runner’s high, but ferrets cannot.

English: Sable short-hair ferret, jill, 1 1/2 ...
English: Sable short-hair ferret, jill, 1 1/2 years old Deutsch: Iltis-farbenes Frettchen, Fähe, 1 1/2 Jahre alt Nederlands: Wildkleur fret, moertje, 1 1/2 jaar (Photo credit: Wikipedia)

Having a runner’s was an evolutionary advantage for early humans and dogs, while ferrets never needed it. It is another reason to believe that we are born to run.

Last year, David Raichlen and his team published a study showing that dogs can experience a runner’s high, but ferrets cannot. They tested 10 humans, 8 dogs and 8 ferrets for endocannabinoids before and after a 30 minute run. Endocannabinoids are molecules associated with runner’s high. The animals were only positively encouraged and never forced. Sure enough, the researchers noticed that the endocannabinoid blood levels were increased after the runs in humans and dogs, but not in ferrets. In humans the raised levels correlated with feelings of well being.

Raichlen and his team concluded that developing a runner’s high must have been an advantage for early humans and dogs, as they had to run to hunt and scavenge for food. Ferrets on the other hand, sleep most of the day. They do not need to run long distances as they tend to hunt their prey in its own burrow or by ambushing it.

Runner’s high

Endurance exercise often gives you feelings of well being, happiness, harmony, lack of pain… Together these feelings are called “runner’s high”, as you are more likely to experience them during long runs than during any other exercise. Not everybody experiences it, and nobody does so every time.

Scientists now think that it is mainly due to endocannabinoids, which are molecules that act on the brain and influence processes such as mood, pain sensation, appetite…Their chemical structure is similar to marihuana.

Our ancestors needed to run to get food, but it was an energy consuming and risky exercise. Scientists believe that having runner’s high was an advantage, as it stimulated them to take the risk and to have (hopefully) more and better food. Over the millions of years that we were hunters-gatherers, our bodies became perfectly adapted to exercise, and even started to need it on a regular basis to keep healthy. Getting a high was a reward for an essential activity. Unfortunately, the modern lifestyle with its sedentary behaviour has jeopardized everything.Running dog

In an interview with the editor of The Journal of Experimental Biology, David Raichlen says that runner’s high fails to make sedentary people physically active because you have to be fit enough to engage in endurance exercise before you can experience it. This explains why running is so hard when you are a beginner, but becomes addictive as you get fitter.

Links between visceral fat, exercise and longevity

A public demonstration of aerobic exercises
A public demonstration of aerobic exercises (Photo credit: Wikipedia)

Exercise improves your health and can make you live longer even if you do not lose weight.

In November 2012, a study in Plos Medicine showed that being more physically active is associated with a longer life, whatever your weight is. Physically active people with a normal weight had the best life expectancy, but being active and overweight or mildly obese (BMI up to 34.9 kg/m2) was better than being inactive with a normal weight. The authors concluded that exercise is beneficial for everybody, and doing a small amount is better than nothing.

In an article published earlier this month in Plos One, Dirk Vissers and colleagues reviewed all the studies looking at the effect of exercise without dieting on visceral fat in overweight and obese people. They noted that exercise reduced visceral fat, even in people who did not lose weight. They also showed than moderate or vigorous aerobic exercise was more effective than low intensity or resistance work.

This could well explain why physically active people do better than sedentary ones. In any case it is excellent news for all of us who train hard but do not manage to lose much weight.

Subcutaneous or visceral

Fat tissue affects your health depending on where it is. If you take in more calories than you need, your body can store the excess energy as subcutaneous (just under the skin) or as visceral fat (in and around organs such as the liver or pancreas).

For more than 50 years now, studies have shown that excess visceral fat leads to chronic diseases such as diabetes, cardiovascular disease and metabolic syndrome. Subcutaneous fat on the other hand, does not put you at a higher risk.

Your waist circumference is a better measure of your visceral fat than your body mass index (BMI). To learn how to measure it, click here.

The problem with visceral fat

Visceral fat behaves as an organ and produces molecules, adipokines. We do not know much about adipokines yet, but scientists have noticed that they can act as hormones. When the visceral fat depot enlarges, the adipokine production becomes disturbed, and this puts you at a higher risk of chronic disease.

A large amount of visceral fat becomes easily inflamed, leading to a chronic low-level inflammatory state which increases your risk even further.

Exercise

Dirk Vissers showed that regular physical activity is associated with a reduction in visceral fat, even if there is little or no change in weight. If you are losing fat, especially visceral fat, you are probably gaining lean body mass. The result can be that your weight stays the same, even though your waist circumference decreases. Obviously, if you are losing weight as well as reducing your waist circumference, you are losing even more visceral fat.

An acute bout of exercise does more than just burning calories

During an acute bout of exercise, the blood flow in fatty tissue increases. It therefore gets more oxygen and a larger amount of several hormones, such as cortisol and adrenalin, than when you are less active. This increases fat mobilisation and affects adipokine secretion.

For 24 hours or so after your workout, fat that comes from your diet will be directed to your muscles instead of being stored in adipose tissue, probably to make sure that you have energy available for your next exercise bout. As a result, your blood levels will be lower and your fatty tissue does not enlarge.

After just one session of aerobic exercise insulin sensitivity (= ability of tissues to respond correctly to insulin) increases by 20% in healthy as well in diabetic people. As insulin resistance (the opposite of insulin sensitivity) is linked to chronic disease and diabetes, this is important for your health. It persists for a day or two.

Training

Chronic exercise or training is just a series of acute bouts. If you exercise on a regular basis, for example every other day, the effects of each bout will continue into the next one, and the accumulation will improve your health much more than a diet can ever do.

As fatty tissue gets mobilised on a regular basis, it becomes more responsive. Scientists believe that sedentary obese people have “inflexible” fatty tissue, which resists stimulation by hormones, and they think that training can correct this.

It is obvious that weight management is more than calculating calories. We still have a lot to learn about it.

Further reading:

D Thompson, F Karpe, M Lafontan and K Frayn. Physical activity and exercise in the regulation of human adipose tissue physiology.  Physiol Rev 2012; 92(1): 157-192

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.

Lactate: your best friend during a run

Lactate is a source of energy that your body can shuttle around. It is not a waste product, and it does nor make you sore.

 

Lactate: a valuable souce of energy

When you are running hard, you need a fast source of energy. Lactate is the end product of the glycolytic or anaerobic metabolism, which is a quick pathway to produce energy by breaking down glycogen or glucose without the need for oxygen. However, that is not the end of the story, because lactate can then be shuttled to other muscle fibres, your heart or your brain, and further broken down to produce more energy. Inactive muscles or the liver can even transform it back into glucose or glycogen and store it. Lactate is therefore a valuable molecule that allows you to move energy around.

Breaking down lactate requires oxygen and this is therefore called the oxidative or aerobic metabolism. It delivers much more energy than the glycolytic metabolism, but it is a slow process. That is why the lactate breakdown cannot follow the production when you are running hard. The clearance by other organs might not keep up either, and the concentration in your blood will increase. When that happens, you have reached your lactate threshold.

“Yes, but I thought lactate was created when my muscles do not have enough oxygen?” you ask. It is true that the glycolytic metabolism does not require oxygen, but the amount of oxygen is never so low that the oxidative energy metabolism has to stop. Lactate accumulates because the oxidative metabolism is much slower than the glycolytic, and the clearance cannot follow the production.

This should not change the way you train. Even though the lactate threshold is not exactly what you thought it was, it is still a good idea to do part of your training at that intensity.

Nothing to do with sore muscles

As lactate is not a waste product, you do not have to “flush it out”. It is taken out of the bloodstream and used even if you do not perform an active cooling down, and it is incapable of making you sore. Soreness usually develops in 24 to 48 hours, while lactate levels are back normal within 2 hours.

Scientists think that muscle soreness develops because fibres get injured by vigorous exercise. The injury is worse if you perform eccentric actions, whereby you contract your muscles while they are lengthened, as for example the quadriceps when you go downhill. You can therefore develop muscle soreness without increasing your lactate levels.

This does not mean that an active cooling down is a waste of time. It does indeed help, but it is not clear why. I you know the reason, please tell me.

Lactate and fatigue

During exercise, an increase in lactate levels coincides with fatigue, but it is still not clear if lactate is a cause or a consequence of fatigue.

It is possible that lactate is just the messenger. To stay alive, there has to be a balance between the chemical substances in your body. Rapidly rising lactate levels might be a signal for your unconscious brain that you could disrupt the balance by exercising too hard for too long, and that you should slow down. Your brain will then make you tired and reduce the number of muscle fibres you can recruit. This theory is still controversial, but it would explain why you cannot keep going hard by using the glycolytic system for very long.

References:

G A Brooks. Cell – cell and intracellular lactate shuttles. J Physiol 2009; 587(Pt23): 5591-5600

R S de Oliveira Cruz, R A de Aguiar, T Turnes et al. Intracellular shuttle: the lactate aerobic metabolism. ScientificWorldJournal 2012, 2012: 420984

E Goes. Benefits of lactate during exercise. Suite 101 02/09/2012

A Philp, A L Macdonald and P W Watt.  Lactate – a signal coordinating cell and systemic function. J Exp Biol 2005; 208: 4561-4575

Why do we get tired during a run?

English: Dr. Tim Noakes at the Department of P...
English: Dr. Tim Noakes at the Department of Physical Education at West Point shortly before delivering a lecture on Exercise Induced Hyponatremic Encethalopathy (Photo credit: Wikipedia)

The classical theory to explain why we have to slow down during a hard run is that our leg muscles do not get enough oxygen anymore; therefore lactate builds up and further work becomes impossible. During longer, slower runs, the theory predicts that we run out of ATP (= the molecule that delivers energy), and that our cells become “poisoned” by by-products of our metabolism. Fatigue is thus seen as a “catastrophe” due to failure of our muscles.

Is that true?

As runners, we cannot help being sceptical. How can this be true if, at the end of a race, we manage to speed up when we see the finish? How is it possible that we run so much better if loved ones cheer us on? Why is motivation so important, even though there is no room for it in this theory?

If our leg muscles are too poisoned to work properly, what is happening to our hearts? Runners do not die from a heart attack at the end of a run, unless they have an underlying disease or abnormality.

Moreover, if this theory is correct, how did our prehistoric ancestors have the strength to defend themselves against wild animals after a hard day hunting?

To make matters even worse for the classical theory, scientific studies have shown that muscle cells still contain oxygen at their maximum work rate. In other words: they do not become “anaerobic” as the lactate concentration starts to increase. They have also demonstrated that athletes are not engaging all their muscle fibres at maximal effort, as you would expect according to the classical theory, but only about 30%.

Another theory

To solve all these contradictions, Prof Tim Noakes has come up with a new theory. He starts from the fact that a correct perfusion of our brains and hearts by oxygenated blood is essential for our survival. He thinks that we regulate unconsciously our running speed to make sure that our hearts and brains have enough oxygen. This means that there must be a “governor” who protects us from exercising so hard that we would damage ourselves. Tim Noakes therefore called his theory “the central governor model”.

The central governor model

At the start of the run, the unconscious brain chooses the pace by recruiting an appropriate number of fibres in the working muscles. Its choice is determined by the expected length and difficulty of the run, and by a long list of other factors, including fitness, fatigue, temperature, motivation, presence of spectators or competitors…

At each step it further adapts the pace according to information coming from the conscious brain such as the distance already covered, or the true difficulty of the terrain. It also uses information from the working muscles, such as the rate of glycogen consumption, and from other unconscious sources, e.g. amount of oxygen in the blood, loss of fluid, rise in core temperature, etc…

In that way the brain aims to prevent catastrophic changes in the body. It does so by reducing the amount of muscle fibres we are using and by making us feel tired. According to this model, fatigue is not just a physical event but an opinion of the brain. In other words: it is an emotion, which can be altered by other emotions and by physical factors.
This explains why we have some energy left for the final sprint, or to speed up when we hear friends and family shout our name.

A partnership between mind and matter

Some scientists find it difficult to accept this model, because the exact pathways and mechanisms are not well understood, but most runners find it very appealing. It indeed explains what we feel. It also makes it possible to be happy when we are tired: our brains are keeping us safe.

References

T D Noakes, A St Claire Gibson, E V Lambert. From catastrophe to complexity: a novel model of integrative central neural regulation of effort and fatigue during exercise in humans: summary and conclusions. Br J Sports Med 2005; 39: 120-124

T D Noakes. Fatigue is a brain-derived emotion that regulates the exercise behaviour to ensure the protection of whole body homeostasis. Front Physiol 2012; 3: 82

R S Richardson, E A Noyszewski, J S Leigh, P D Wagner. Lactate efflux from exercising human skeletal muscle: role of intracellular PO2. J Appl Physiol 1998; 85(2): 627-634

R S Richardson, S C Newcomer, E A Noyszewski. Skeletal muscle intracellular PO2 assessed by myoglobin desaturation: response to graded exercise. J Appl Physiol 2001; 91(6): 2679-2685

A St Clair Gibson, T D Noakes. Evidence for complex system integration and dynamic neural regulation of skeletal muscle recruitment during exercise in humans. Br J Sports Med 2004; 38:797-806

J P Weir, T W Beck, J T Cramer, T J Housh. Is fatigue all in your head? A critical review of the central governor model. Br J Sports Med 2006; 40: 573-586