sportsdietpain

Why do we get muscle cramps while exercising?

The answer to this question is quite simply…… we still don’t know. Most people, even trainers, think that it is due to the loss of salts or electrolytes but in the past few years the scientific evidence out there clearly does not support this hypothesis. But most people still believe this thanks, in part, to the help of sports drinks.

This myth started almost 100 years ago in shipyards and mines, where workers were cramping up.  They did an analysis of their sweat which showed that it contained high levels of chloride (an electrolyte). So, they came to the conclusion that loss of electrolytes was the reason for the workers’ muscle cramping, along with dehydration. The problem with this is that they never checked the sweat of the people that were not cramping up. So, it sounded logical but this hypothesis had a couple of weak links.

1. The first one being: When we sweat, we tend to sweat all over our body, meaning we are losing electrolytes equally in all  parts of our body. But somewhat surprisingly, exercise-associated muscle cramps only happen in the muscles that have been used extensively for the exercise. Kind of weird, right?
2. When we sweat we lose much more water than electrolytes. In fact the loss of electrolytes is very low. Meaning that the concentration of electrolytes in our body is actually going to be higher than before doing the sport or activity. Also, two studies done on  ultramarathoners , showed that the runners who cramped up had a significantly lower sodium concentration (this means these runners were over-hydrated ), and lost less weight, and the more direct measures of the fluid in their blood showed they were better hydrated (1-4).  Amazing, isn’t it?
3. Whenever we cramp up, we stretch and that usually makes the cramp go away for a while. So, if cramping is caused by loss of electrolytes or dehydration, how can simply stretching the muscle help us getting rid of our cramp?

Then why do we cramp up while exercising? Well, there is a new theory out there that basically says we cramp up because of fatigue. Let me explain: Muscle contraction is stimulated by a nerve, called the alpha motor neuron. One of the places this neuron gets its information from is muscle spindles and the golgi tendon organ.

1) Muscle spindles- We have probably all experienced the classic reflex, where a doctor or friend taps on the knee with a small hammer and you extend the leg. So, whenever your muscle is stretched too much, the muscle spindles activate and produce a muscle contraction (5).

2) Golgi tendon organ- Does the opposite, when it feels that a muscle is contracting too much, it will send a signal telling the muscle to relax (5).

Fatigue has been shown to increase the rate of muscle spindle and decrease the rate golgi tendon organ (5). Most muscle exercise cramps happen at the end of a race.

I will leave it at here for today. In my next blog I will talk about what we can do to try to prevent muscle cramps.

1.  Schwellnus, M.P, Nicol R, Laubscher R, Noakes T.D Serum electrolyte concentrations and hydration status are not associated with exercise associate muscle crampint (EAMC) in distance runners. Brit J Sports Med 38(4): 488-92.
2. Miller K, Knight K, Mack G, et al. Three percent hypohydration does not affect the threshold frequency of electrically-induced muscle cramps. Med Sci Sports Exerc. 2010;42:2056-2063.
3. . Braulick K, Miller K, Albrecht J, Tucker J, Deal J. Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency. Br J Sports Med. 2012;47:710-714.
4. Sulzer N.U, Schwellnus M.P, Noakes T.D. Serum electrolytes in Itronman triathletes with exercise-associated muscle cramping. Med Sci Sports Exerc 3(7): 1081-85.
5. Schwellnus M.P, Derman E. W, Noakes T.D. Aetiology of skeletal muscle cramps during exercise: A novel hypothesis. Journal of Sports Sciences, vol 15, pp 277-85, 1997.

The myth of Lactic Acid!

I think we have all heard that muscle soreness is produced by lactic acid. That somehow, when you train your body, it produces lactic acid and that is what causes the pain after an intense workout. But the truth of the matter is that this is not true. Scientists have proven that years ago but the myth still persist, even within the sports community. The myth started back in the 1920´s when researchers showed that the exposure of frog legs to high levels of lactic acid interfered with the ability of the muscles to contract in response to electrical stimulation. Later research determined that lactate was produced through the breakdown of glucose without the help of oxygen. So, they concluded that fatigue happened at high exercise intensities because the cardiovascular system could no longer supply the muscles with enough oxygen to keep up with muscular energy demands. This would eventually lead the body to rely on the breakdown of glucose without the help of oxygen, which would lead to the buildup of ¨lactic acid¨. But now we know that is not true, in fact, lactic acid is a chemical that your body produces to feed your muscles so that you can move (1). So it really does the opposite of what a lot of people think!!

So what produces muscle soreness? It is still not 100% certain but most scientist think that next-day soreness is more likely the result of damage to muscle and connective tissue, or inflammation. (That is normal, even good, so don´t get scared)

But the real question most people want to know is what they can do to get rid of the muscle soreness that sometimes occurs after training? And like I said in one of my previous post (click here), not that much! Massage, stretching, it feels good and it relaxes but it won´t prevent you from having that uncomfortable feeling the next day (2-4).

References:

• Cairns SP. Lactic acid and exercise performance: culprit or friend? Sports Med 2006;36 (4) 279-91.
• Lund et al. The effect of passive stretching on delayed onset muscle soreness, and other detrimental effects following eccentric exercise.Scandinavian Journal of Medicine & Science in Sports 1998.
• Cheung et al. Delayed onset muscle soreness: treatment strategies and performance factors.Sports Medicine 2003 .
• Weber et al. The Effects of Three Modalities on Delayed Onset Muscle Soreness.  Journal of Orthopaedic & Sports Physical Therapy 1994.

Proteins- Part 1

We have all heard of proteins at one point or another in our life but do we really know what they are or do? Let´s find out.

Proteins are made up of amino acids. There are 20 amino acids. These amino acids can be arranged in a million different ways to create millions of different proteins. Amino acids can be categorized as essential or non-essential. Essential amino acids are those that we cannot create through our own metabolism. Therefore we need to obtain them through foods. Non-essential amino acids are those that our body can synthesize (build). One gram of protein contains 4 calories (in comparison, one gram of carbohydrates also contains 4 calories, and one gram of fat 9 calories).  Proteins are used by the body to:

1. Build, strengthen and repair/ replace things, such as tissue.
2. Make antibodies for our immune system.
3. Make hormones.
4. Muscle contractions.
5. Make enzymes.
6. Transport things.
7. Store things .

Dietary thermogenesis (DT)  is the process of energy production in the body caused directly by the metabolizing of food consumed. Consuming more protein causes a greater energy expenditure than consuming fat and carbohydrates (2) ( click here to read more). And diets high in protein are more important than the  low carb or low fat component in achieving body weight loss and weight maintenance (3). This is because, higher protein diets generally help people lose less muscle and more fat at the same calorie intake. (4-7). However, after a certain point eating more protein isn´t going to help you lose any more fat. And in extreme cases it could even make you gain fat (it´s quite hard to turn protein into fat but it could happen). But with all this said, most people probably eat less proteins than they are suppossed to. Here is what is recommend by the experts (8):

• Infants require about 10 grams a day.
• Teenage boys need up to 52 grams a day.
• Teenage girls need 46 grams a day.
• Adult men need about 56 grams a day.
• Adult women need about 46 grams a day

but if you ask me, it probably woudn´t hurt if we consumed a little bit more especially if you are exercising (9)!  But, I will explain that in my next blog, where I will also talk about if eating too many proteins is bad for the kidneys and how much should we be consuming.

So to summarize:

1. Proteins cause a greater energy expenditure, when you metabolize them, than consuming fat and carbohydrates.
2. Diets high in protein are very important in achieving body loss and body maintenance. .
3. Proteins are made up of amino acids. There are 20 amino acids, that can be divided into essential and non-essential.
4. 1 gram of protein contains 4 kcla.

P.S . By the way here is a great page of a friend of mine who does customize cell, tablet and Ipad cases. Www.personalaizer.com

References

1. http://www.ncbi.nlm.nih.gov/books/NBK26911/
2. Westerterp KB. Diet induced thermogenesis. Nutr Metab (Lond),2004 Aug 18;1(1):5
3. Soenen S, Bonomi AG, Lemmens SG, Scholte J, Thijssen MA, van Berkum F, Westerkep-Plantenga MS. Relatively high-protein or `low -carb´ energy-restricted diets for body weight loss and body weight maintenance. Physiol Behav, 2010 Oct 10;107(3):374-80.
4. Layman DK, Evans E, Baum JI, Seyler J, Erickson DJ, Boileau RA. Dietary protein and exercise have additive effects on body composition during weight loss in adult wome. J Nutr. 2005;135(8):1903-10.
5. Leidy HJ, Carnell NS, Mattes RD, Campbell WW. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese wome. Obesity.2007;15(2):421-29.
6. Layman DK. Protein quantity and quality at levels above the RDA improves adult weight loss. J Am Col Nutr.2004;23(6)
7. Wycherley TP, Moran LJ Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein,low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr.2012;96(6):1281-98.
8. Source for Acceptable Macronutrient Distribution Range (AMDR) reference and RDAs: Institute of Medicine (IOM) Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. This report may be accessed via www.nap.edu
9. Wolfe RR, Deutz NE. Is there a maximal anabolic response to protein intake. Nutr, 2013 Apr,32(2):309-13