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RER Value Guide

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Data Source: Zamparo P, Bonifazi M (2013). Bioenergetics of cycling sports activities in water.

Coded for Swimming Science by Cameron Yick

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L-Arginine Supplementation and Nitric Oxide

Take Home Points:


  1. L-arginine supplementation shows much more promise in a clinical setting than a sports performance setting. 
  2. Swimmers may notice greater nitric oxide induced vasodilation from dietary nitrates derived from beetroot juice than L-arginine supplementation. 
  3. Dietary nitrates are converted to nitric oxide, which will again enhance vasodilation and oxygen distribution. This is supported by available literature. For example,
  4. In 2011, Ferreira and Behnke found that dietary nitrates in the form of beetroot juice lowered the oxygen cost of exercise.

L-arginine is a non-essential amino acid (meaning our body can synthesizes it, to an extent, on its own). As a nutrient within the body it plays a part in a variety of functions including immune functions. However, this supplement is mostly known as a precursor to nitric oxide within the body. Most importantly, nitric oxide increases vasodilation.

There is plenty of research on arginine supplementation, which supports its effects as a vasodilator within a clinical setting. For example, Orozco-Gutiérrez et al. (2010), found that after 2 months of supplementing L-arginine at 8g/day, patients had a significant improvement in right ventricular function in heart failure patients with preserved ejection fractions. Authors suggest “decreasing systolic pulmonary artery pressure”, which would likely be due to increased vasodilation. A Pubmed search results in many clinical studies such as the Orozco- Gutiérrez study, which support arginine supplementation’s efficacy related to heart disease.

Arginine and Sports Performance

It is important to note that research has been less conclusive in the area of sports performance when it comes to L-arginine supplementation.

The theory would be:

Arginine supplementation; increased nitric oxide; increased vasodilation; increased nutrient and oxygen delivery to muscles during training; improved swimming performance

Research does exist that supports arginine supplementation as a performance enhancer. In 2010
Bailey et al. found that 6g of arginine supplementation reduced the cost of moderate-intensity exercise and extended time to exhaustion in severe-intensity exercise. However, the results of more recent studies have not supported the efficacy of arginine as a performance enhancer.

In 2011, Tang et al. found no change in any measured markers of nitric oxide synthesis after 10g of L-arginine supplementation. Furthermore, blood flow remained the same between the arginine-supplemented group and control group in both an exercised-state and sedentary-state. Authors conclude, “an oral bolus (10 g) of arginine does not increase NO [nitric oxide] synthesis or muscle blood flow. Furthermore, arginine does not enhance mixed or myofibrillar MPS either at rest or after resistance exercise beyond that achieved by feeding alone.”

Similarly, Vanhatalo et al. in 2013 found no change from 6g of arginine supplementation on biomarkers of nitric oxide synthesis, oxygen cost of exercise, or on subjects exercise tolerance. Interestingly, Vanhatalo was a co-author of the 2010 Bailey study.

References

  1. Bailey, S. J., Winyard, P. G., Vanhatalo, A., Blackwell, J. R., DiMenna, F. J., Wilkerson, D. P., Jones, A. M. (2010). Acute l-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high intensity exercise tolerance. Journal of Applied Physiology Published 1 November 2010 Vol. 109no. 5, 1394-1403
  2. Ferreira, L. F., Behnke, B. J. (2011) A toast to health and performance! Beetroot juice lowers blood pressure and the O2 cost of exercise. Journal of Applied Physiology Published 1 March 2011Vol. 110 no. 3, 585-586
  3. Orozco-Gutiérrez, J. J., Castillo-Martínez, L.,
 Orea-Tejeda, A., Vázquez-Díaz, O., Valdespino-Trejo, O., Narváez-David, R., Keirns-Davis, C., Carrasco Ortiz, C., Navarro-Navarro, A., Sánchez-Santillán, R. (2010). Effect of L arginine or L-citrulline
oral supplementation on blood pressure and right ventricular function in heart failure patients with preserved ejection fraction. Cardiology Journal 2010, Vol. 17, No. 6, pp. 612–618
  4. Tang, J. E., Lysecki, P. J., Manolakos, J. J., MacDonald, M. J., Tarnopolsky, M. A., Phillips, S. M. (2011). Bolus Arginine Supplementation Affects neither Muscle Blood Flow nor Muscle Protein Synthesis in Young Men at Rest or After Resistance Exercise. The Journal of Nutrition February 1, 2011 vol. 141 no. 2 195-200
  5. Vanhatalo, A., Bailey, S.J., DiMenna, F.J., Blackwell, J.R., Wallis, G.A., Jones, A.M. (2013). No effect of acute L-arginine supplementation on O₂ cost or exercise tolerance. European Journal of Applied Physiology 2013 Jul;113(7):1805-19.

By Kevin Iwasa-Madge BASc, CISSN owner of iMadgen Nutrition, and as a former top-5 finisher in the world as a freestyle wrestler, Kevin embodies the lifestyle of an elite athlete. Kevin completed his undergraduate degree at the University of Guelph in the Applied Human Nutrition. This clinically focused program allowed him the opportunity to address a range of diseases from a nutritional approach. After graduation Kevin attained his certification in sports nutrition from the International Society of Sports Nutrition.

Athletically, Kevin has been an elite wrestler for over 10 years, competing for both the University of Guelph and Team Canada. Kevin is a former First Team All-Canadian, Academic All-Canadian, and Canadian Champion. As a varsity athlete, Kevin was short-listed for the prestigious Student-Athlete of the Year award. He currently trains with and competes for the Guelph Wrestling Club and National Team. Over the years, Kevin has worked with a range of individuals, from those looking to improve their overall health, to rugby player, football players, swimmers, professional fighters, wrestlers, endurance athletes and more.

Nitrates and Sports Performance

Take Home Points on Nitrates and Sports Performance:
  1. Beetroot juice has potential for sports enhancement. 
  2. Beetroot juice has minimal negative effect, as consuming more vegetables is a healthy ergogenic aide.
I hear a lot about drinking beet juice to help sports performance. Is there any science to
support drinking it?
Yes. Beet juice contains relatively high levels of nitrate (NO3-), and nitrate from dietary sources is converted to nitrite (NO2-) by commensal bacteria in the mouth, and the nitrite is then absorbed in the blood stream. Nitrate reductase enzymes (which convert nitrate to nitrite) are found in certain bacteria in the mouth or intestines[1]. Such bacterial nitrate reductases contribute significantly to a person’s endogenous nitrite pool. 

Elevated nitrite levels improve may act to improve athletic performance through three different mechanisms, although the details are still being resolved.

1. Improved blood flow through vasodilation. Nitric oxide (NO) regulates arterial blood flow by causing smooth muscle cells which line the arteries to relax and open the vessel, allowing blood flow to increase. Nitric oxide was initially found to be produced by the conversion of L-arginine to L-citrulline by one of three enzymes, the nitric oxide synthases (NOS’s) including endothelial NOS (eNOS) neuronal NOS (nNOS) and inducible NOS (iNOS). However, these enzymes are oxygen dependent. For a long time after nitric oxide (NO) was discovered, scientists wondered how the body could rapidly deliver NO to locations with low oxygen where NO was needed. 

Recently, nitrite itself has been shown to be a circulating storage pool for NO that the body can rapidly activate when needed[2]. Rapid conversion of nitrite to NO can occur under ischemic conditions (low pH, low partial pressure of oxygen (pO2))[3]. There are several enzymes which may act to reduce nitrite to NO, including deoxyhemoglobin, deoxymyoglobin, xanthine oxoreductase (XOR), neuroglobin, eNOS, and components of the mitochondrial electron transport chain[4]. The different nitrite reductase “enzyme” systems operate along a range of physiological and pathological hypoxia, with hemoglobin reducing nitrite at an oxygen tension from 60 mm Hg down to 20 mm Hg, myoglobin active below 4 mm Hg, and xanthine oxoreductase and acidic reduction reducing nitrite at zero oxygen and low pH[5].

2. Reduced tissue oxygen demand through inhibition of mitochondrial respiration. NO reversibly inhibits mitochondrial respiration[6]. Partial inhibition of mitochondrial respiration can regulate tissue oxygen gradients and conserve oxygen, particularly in conditions of physiological hypoxia (lack of oxygen). Inhibition of the most actively respiring mitochondria and those closest to the oxygen source would allow oxygen to diffuse beyond these mitochondria and further into the tissue to those sections of the tissue that are more distant from the oxygen source. This extension of the oxygen gradient deeper into the tissue would also extend the NO gradient in the tissue, thereby increasing the apparent bioavailability of both oxygen and NO[7].

3. Improvement in the efficiency of muscle contractility.
Some studies show that NO may improve muscle contractility, and therefore improve strength. It is hypothesized that increased levels of nitric oxide following supplementation may reduce the ATP cost of force production. Reduction of ATP use may be a consequence of nitric oxide’s regulatory effect on the ATP consuming processes of sarcoplasmic reticulum calcium pumping or myofibrillar actin-myosin interaction in force production. There is evidence that small increases in NO improves muscle metabolism, preventing excess calcium release and subsequently modulates the ATP cost of force production[2].

Do Nitrates it really help your performance? 

Nitrate consumption has recently been referred to as “legal blood doping”[8]. The effects are roughly similar to blood doping (red blood cell transfusion or erythropoietin (EPO) administration, which are of course illegal in sports) although most people show improved performance with blood doping, while not everyone gets a benefit from nitrates. Nitrate consumption shows a roughly 15% improvement in time to exhaustion, and a 2-3% improvement in overall performance. In one study of well-trained cyclists in a 50 mile time trial, athletes whose nitrite levels increased by about 100 nM over baseline showed a 2-3% improvement in overall performance[9]. Nitrates have also been found to improve the efficiency (i.e., they can reduce the energy cost) of exercise as indicated by a 4%–5% reduction in oxygen uptake at steady state.

Nitrate consumption seems to help some people more than others. Some people may be “responders” and others “non-responders” to dietary NO3- supplementation. In addition, the duration and intensity of different types of exercise have not been thoroughly studied. In one study4, the number of non-responders (in terms of exercise capacity) decreased as the dose of nitrate ingested increased. Two of the subjects who did not respond at the lowest dose (4.2 mmol NO3-) did respond to the larger doses, and one subject who did not respond to low or medium doses of nitrate (4.2 or 8.4 mmol) did respond to the 16.8-mmol dose. This suggests that some individuals will require a larger acute dose than others to elicit any positive effects on exercise capacity from dietary NO3- ingestion.

In swimming, a recent study involving trained masters swimmers showed an increase in the workload at anaerobic threshold which was significantly increased by beet juice, and there was also a reduction in the aerobic energy cost of swimming at submaximal workload[10].

I really can’t stand beets, but I don’t want to mess around with supplements. Is there anything else I can eat or drink to get this benefit?
Yes! Spinach, celery, arugula, and other vegetables are relatively high in nitrates. Dark green leafy vegetable such as kale and chard are also good candidates. Interestingly, the nitrate levels in hot dogs are actually much lower than what is found in vegetables. Nitrate supplements are also widely available.

How much beet juice should I drink? When should I drink it?

Studies have shown that plasma nitrite levels are maximal at about 2-3 hours after ingesting bee
t juice[11]. However, there are appreciable inter-individual differences in the speed with which ingested NO3- is reduced to NO2-, which may preclude any more specific advice other than to consume NO3- some 2–3 h before the start of exercise. In some cases, nitrite begins to increase at least as early as 1 hour after consumption.

Nitrite levels appear to be elevated for up to 8 to 12 hours after nitrate consumption in the absence of exercise. However, this depends on the amount consumed, and is likely to be dependent on the duration and intensity of exercise. 

A few caveats: Be sure not to take nitrite as a supplement – too much of that can be potentially lethal[12]! Also, don’t use nitrates if you are taking Viagra or similar medications as the combination can cause a severe drop in blood pressure[13]. If you are unsure, be sure to consult your doctor or pharmacist. Don’t use antiseptic mouth wash while you are consuming nitrates, as that can kill the bacteria that convert nitrates to nitrites.

Bottom line: You may want to try consuming different amounts of nitrates at different times. If you compete in endurance events such as marathons or open-water swimming events where you are allowed to consume drinks part way through, you might want to drink some beet juice then. After all, would it kill you to eat your vegetables?

References

  1. Webb AJ, Patel N, Loukogeorgakis S, Okorie M, Aboud Z, et al. (2008) Acute Blood Pressure Lowering, Vasoprotective, and Antiplatelet Properties of Dietary Nitrate via Bioconversion to Nitrite. Hypertension 51: 784-790.
  2. Cosby K, Partovi K, Crawford J, Patel R, Reiter C, et al. (2003) Nitrite reduction to nitric oxide by deoxyhemoglobin vasodilates the human circulation. Nature Medicine 9: 1498-1505.
  3. Gladwin MT, Schechter AN (2004) NO Contest: Nitrite Versus S-Nitroso-Hemoglobin. Circ Res 94: 851-855.
  4. Tiso M, Tejero J, Basu S, Azarov I, Wang X, et al. (2011) Human Neuroglobin Functions as a Redox-regulated Nitrite Reductase. J Biol Chem 286: 18277-18289.
  5. Shiva S, Sack MN, Greer JJ, Duranski M, Ringwood LA, Burwell, et al. (2007) Nitrite augments tolerance to ischemia/reperfusion injury via the modulation of mitochondrial electron transfer. J Exp Med 204: 2089-2102.
  6. Loke KE, Laycock SK, Mital S, Wolin MS, Bernstein R, et al. (1999) Nitric Oxide Modulates Mitochondrial Respiration in Failing Human Heart. Circulation 100:1291-1297.
  7. Thomas DD, Liu X, Kantrow SP, Lancaster JRJ (2001) The biological lifetime of nitric oxide: Implications for the perivascular dynamics of NO and O2. PNAS 98: 355–360.
  8. http://www.telegraph.co.uk/health/dietandfitness/9546330/Beetroot-juice-may-help-beet-your-best.html
  9. Daryl P. Wilkerson et al., “Influence of acute dietary nitrate supplementation on 50 mile time trial performance in well-trained cyclists” Eur J Appl Physiol (2012) 112:4127–4134
  10. Marco Pinna et al., “Effect of Beetroot Juice Supplementation on Aerobic Responseduring Swimming”, Nutrients 2014, 6, 605-615; doi:10.3390/nu6020605
  11. Lee J. Wylie et al., “Beetroot juice and exercise: pharmacodynamic and dose-response Relationships” J Appl Physiol 115: 325–336, 2013
  12. Andrea Petróczi and Declan P Naughton, Potentially fatal new trend in performance enhancement: a cautionary note on nitrite, Journal of the International Society of Sports Nutrition 2010, 7:25
  13. http://www.medicinenet.com/script/main/art.asp?articlekey=8229
James Silver, PhD, is the Founder and President of Silver Medical, a first-to-market medical diagnostic company addressing the large unmet clinical need of real-time detection in sports-related concussion. The technology is based on changes in nitric oxide. He has 20 years of experience in medical device research and development in both small start-ups and large firms, taking products from concept through commercialization. He is the author or co-author on 16 scientific publications including as an invited author on nitric oxide as a diagnostic, and is a named inventor on 13 issued US patents including several related to nitrite measurement. He holds a Ph.D. in Chemical Engineering with specialization in vascular biology and polymer science.

Beetroot Juice and Swimming

Take Home Points on Beetroot Juice and Swimming: 
  1. A week of beetroot juices improves aerobic and anaerobic swimming capacity in moderately trained Masters swimmers.
Many vegetables contain inorganic nitrates (NO3-) which have a beneficial impact on body function. It is believed nitrates can reduce nitrite and in turn to nitric oxide, which influences blood dynamics and muscle metabolism. Previous research suggests beetroot juice enhances nitric oxide production in the muscle, increased blood flow and oxygen delivery.

Beetroot juice supplementation has been tested on other sports, but not in swimming, likely due to the difficulty of testing energy metabolism...typical excuse!

Pinna (2014) had fourteen trained Masters swimmers who trained an average of 6.5 hours per week performed an incremental tethered swimming test. Pretty much, the researchers tied a rope around the swimmers and had them swim against an elastic rope which measured force and when the force was impaired the test stopped. Here it is specifically:

"By means of a dynamometer, the tension applied to the elastic rope was constantly monitored on the display. Continuous vocal feedback was provided by the researcher who checked the dynamometer to an assistant who moved a pole with a coloured signal fixed at the extremity and immersed in the water forward or backward. The tested swimmer was instructed to follow the signal so that the assistant could adjust the tension applied to the rope simply by moving the pole forward or backward."




Then, the subjects performed the same test after a week of beetroot juice supplementation. Each athlete consumed 0.5 l/day organic beetroot juice containing about 5.5 mmol of inorganic nitrate. 

The results from this study demonstrate a significant increase in workload at anaerobic threshold with the beetroot juice supplementation. aerobic energy cost was also significantly reduced during the beetroot juice supplementation. Heart rate, VO2, VCO2, and pulmonary heart rate were not significantly different between groups. 
These results seem positive, but things to keep in mind:
  1. There was no control group, perhaps the swimmers were better trained in a week or were simply more familiar with the testing procedure resulting in better performance.
  2. The swimmers were moderately trained Masters swimmers, like the other research and my suggests a while back, beetroot juice seems beneficial for the moderately trained. However, the supportive research on elite athletes (especially swimmers) is lacking. 
  3. Improved anaerobic and aerobic testing is great, but what about performance? Now, this doesn't mean improving energetics is irrelevant, but does suggest energetics aren't the main test. Remember, medals aren't awarded in practice.
Like I stated previously, "It is clear, more research is needed on elite and trained athletes. Moreover, the reason for potential improvement is still muddy even in un- or moderately trained athletes. Personally, for [highly] trained populations, I don't see nitrates or beets providing any ergogenic benefit."

Luckily, consuming extra veggies and nitrates is not harmful, so give a week of beetroot juice a try, after all it is a healthy, relatively cheap ergogenic aide!

References:
  1. Pinna M, Roberto S, Milia R, Marongiu E, Olla S, Loi A, Migliaccio GM, Padulo J, Orlandi C, Tocco F, Concu A, Crisafulli A. Effect of beetroot juice supplementation on aerobic response during swimming. Nutrients. 2014 Jan 29;6(2):605-15. doi: 10.3390/nu6020605.
By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the owner of COR, Strength Coach Consultant, Creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

Creatine for Swimmers

Take Home Points on Creatine for Swimmers:
1. Creatine monohydrate is the most effective and most researched form of creatine supplement
2. 20% of athletes do not respond to creatine supplementation
3. May improve competition performances in shorter races (i.e. 50m, 100m, 200m)
4. May aid in training intensity during dry-land training and ultra-short race pace training
5. May hinder competition performances in longer races

You have probably heard of creatine before.  But do you know what it actually is? How it works? Or the possible role it can play for swimmers?

First, it is important to know that creatine is not prohibited by WADA.  It is also widely accepted as an ethical performance-enhancing supplement, and is in no way, shape, or form associated with steroids. It is also important to know how creatine works in the body so that we can start to understand the concepts and uses of a creatine supplement.  The following are the basic facts that you or your athletes need to know about creatine’s role in the human body.

Internal Creatine (In The Body)

Lets start with phosphocreatine, or creatine phosphate (CP).  CP is a naturally occurring energy store in the human body. Creatine is a peptide containing a high-energy phosphate. CP’s role is to donate its phosphate group to form ATP (our body’s primary source of energy).  This occurs as our muscular ATP stores become depleted, typically within the first 10 seconds or so of maximal intensity exercise (e.g. 25m sprint).  This is often known as our ATP-CP energy system. 

External Creatine (Supplements)

Does it actually work?

In short, yes, creatine supplementation works.  Resting CP levels are typically around 125mmol/kg of muscle.  However, the body seems to be able to store around 160mmol/kg before hitting a ceiling where it will not store any more.  About 80% of athletes who supplement creatine will experience an increase in ATP-CP related performance.  This is due to a rise in resting CP stores from around 125mmol/kg to the 160/mmol/kg limit.  (20% are considered “non-responders” wherein they rest closer to their ceiling or their ceiling is below average, or more likely a combination of the two).  For “responders”, the almost 30% increase in muscular CP directly translates to increased duration of the ATP-CP system function.  Simply put, more creatine means more energy for muscles.

CP is the body’s internal form of creatine. Like I said above, CP is creatine bound to phosphate.  Creatine monohydrate is THE basic form of supplemental creatine.  Wherein a creatine molecule is bound to 1 water molecule.  And, with so many variations of creatine on the market, it would take quite a while to find the research and compare each and every type of creatine.  So, instead of getting into all of this, I am going to focus on the supplementation of creatine monohydrate, as it is the most researched and proven to work (You’ll have to take my word for it).

Dosing Protocol

So bottom line, creatine monohydrate does its job of increasing CP stores.  Next lets talk about how to use this supplement.  The following is a typical, well-researched procedure for supplementing with creatine:

·      Loading phase (5 days) – 20g of creatine monohydrate, taken in 4 separate servings throughout the day (4x5g). 

·      Maintenance phase – 5g of creatine monohydrate taken once per day. Realistically, even 3g/day would probably do fine for maintaining saturated CP stores.

Typically creatine monohydrate will come with a 5g scoop.  If yours doesn’t have a scoop, 1 tsp is approximately 5g.  Now the loading phase is not necessary to maximize creatine phosphate (CP) stores, but it will allow you to do so quicker (approximately 5 days).  Without a loading phase, a maintenance dose will eventually maximize creatine phosphate stores, but will take much longer (20-30 days). 

Some research indicates that taking a serving of creatine following a training session may be the most effective way of absorbing it.  However, the reality of it is this: when you take your creatine probably won’t make a difference since you will be maxing out your CP stores regardless. 

The take home message here:

Don’t get too anxious about timing your creatine ingestion.  Just try and get 5g/day.

If you miss a dose one day, carry on as if it never happened, it takes 4-6 weeks for CP stores to return to normal levels. It won’t happen to you in a day!

Uses for Swimmers

Remember which energy system creatine is fuelling.  The ATP-CP system lasts seconds, not minutes!  Creatine supplementation will improve performance in shorter races (i.e. 50m Freestyle) rather than longer ones.  It is interesting to note that when CP donates its phosphate to form ATP, it binds up a H+ ion.  H+ ions are responsible for muscular acidosis, which decreases muscle contraction strength.  You may know this better as that “lactic acid burning”.  So, swimmers competing in races than venture into a few minutes’ duration (e.g. 100m, 200m races) may benefit from increased CP stores as a result of creatine supplementation.

However, even swimmers that don’t compete in 50m, 100m, 200m races may still benefit from creatine supplementation in their high intensity training (e.g. ultra short race pace training USRPT).  Additionally, if these athletes are doing weights in dry-land training with the goal of producing some nervous adaptation, then creatine will help them hit those last few reps with speed. Keep in mind that the harder a swimmer can go in practice or training, the greater their adaptation will be.  This will translate to improved competition performance. 

A typical side-effect is weight gain of several pounds.  It happens quite rapidly.  This is fine, safe, and expected.  With increased CP stores in muscles comes increased water retention as well.  Now, this creates an interesting issue from the propulsion/drag standpoint.  For athletes that compete in 50m, 100m, 200m races, having loaded CP stores probably “outweighs” the weight gain, because of the improved power output in those races.  Athletes who compete in longer events may want to utilize a creating supplement in training to elicit greater adaptation, but cycle off before a competition to lose the additional water weight.  If this is the case, the athlete should cease supplementing creatine for about 4 weeks before the competition.  This should be adequate time for CP stores to return to normal levels, and the body to shed the excess water weight.

By Kevin Iwasa-Madge BASc, CISSN owner of iMadgen Nutrition, and as a former top-5 finisher in the world as a freestyle wrestler, Kevin embodies the lifestyle of an elite athlete. Kevin completed his undergraduate degree at the University of Guelph in the Applied Human Nutrition. This clinically focused program allowed him the opportunity to address a range of diseases from a nutritional approach. After graduation Kevin attained his certification in sports nutrition from the International Society of Sports Nutrition. 

Athletically, Kevin has been an elite wrestler for over 10 years, competing for both the University of Guelph and Team Canada. Kevin is a former First Team All-Canadian, Academic All-Canadian, and Canadian Champion. As a varsity athlete, Kevin was short-listed for the prestigious Student-Athlete of the Year award. He currently trains with and competes for the Guelph Wrestling Club and National Team. Over the years, Kevin has worked with a range of individuals, from those looking to improve their overall health, to rugby player, football players, swimmers, professional fighters, wrestlers, endurance athletes and more.


Is Chocolate Milk a Good Recovery Aide for Swimmers?

Take Home Points on Is Chocolate Milk a Good Recovery Aide for Swimmers?
  1. Milk has a beneficial protein to carbohydrate ratio for aiding recovery.
This question was received from one of our readers. If you have a question for the
Swimming Science team, e-mail us today or tweet @swimmingscience #swimsciq! What are you waiting for? Send us a question today!

[Editors Note: A recent research article [which is available for free] was just released about milk compared to Casein].

Question: 
What is up with chocolate milk? Is it a good recovery aide? If so, how much does a 120
high school female need after a workout? What other supplements/nutrients are helpful after practice? Thanks!

Answer: 
Short Answer: Yes.
Extended Answer: Chocolate Milk has been touted as a performance enhancer/ recovery aid largely throughout the sports community since at least the new millennium.  The basis in this comes from the idea that chocolate milk has an ideal ratio of carbs to protein, which helps deliver protein to damaged muscle tissue.  This thought is based around the fact that the sugary additives in the chocolate milk create a higher insulin response (which is the body’s nutrient ‘carrier’).  In theory this is great, higher carb levels lead to higher protein/nutrient content being shuttled to skeletal muscle to promote healing—so far so good.

One area that is overlooked in this debate, however, is the breakdown of types of protein in milk.  The two major types of protein are casein, commonly found in supplements which advertise ‘time-released formulas’ or ‘overnight recovery aide’, as well as the more known whey protein.  Whey is the type of protein which receives the majority of the media hype, as well comprises most protein supplements.  You may be able to tell a whey protein product from the phrases on its package saying things similar to ‘rapidly digesting’ or things of this nature. 

One idea recent scientific evidence is pointing to, is that types of protein, and release patterns may not relate to recovery as significantly as we previously thought.  But one other benefits of whey protein is that is highly insulinogenic; this means that the whey protein in itself releases a large surge of this insulin that we’ve been talking so much about (whey protein causes about a 1:1 spike in insulin when compared to simple sugars).  So what does this mean?  The current idea in nutrition is that insulin caused by the sugary additives in the chocolate milk creates releases a surge in insulin, which can then shuttle the protein to skeletal muscle which has been damaged by vigorous activity (in this case a swimming practice or meet), but this new research suggests that whey releases enough insulin itself to do the job of the sugar, making the sugary additives obsolete.

So as of this point in the article, it seems like I’m making the case for regular milk, over chocolate—but both of which, have their place.  While the caloric reduction, as well as the insulinogenic benefits from the whey may seem to do the job in white milk, the extra calories of the sugar might be more beneficial for athletes (in this recovery setting).  Because the body uses primarily muscle glycogen (sugar stored in the muscle) during intense swimming bouts, restoring this as soon as possible after exercise is important, and chocolate milk just happens to be a convenient way to do so. 

For amount of chocolate milk, a 12-16 oz. container, which you may find at the store is perfect.  You don’t really need to worry about specific volumes, or calorie counting, until your diet is already extremely regimented.  Of course there is the issue of lactose intolerance, which is extremely common, and grows more prevalent as we age.  Under this circumstance, obviously it varies by the individual.  Many can get away with a single serving of milk, but others cannot.  If you experience gastrointestinal upset from milk, it should be avoided; however, if you are capable of digesting this with no adverse effects, it can be very beneficial.

One thing I find very commonly with athletes is that, when they pick a chocolate milk product, they go for the low fat.  This is also not what you want, as I said before, this post workout period is a great time to consume more calories to recover.  Fat is no exception to this rule.  For years fat has been vilified as a main cause of heart disease, inflammation, and a laundry list of other problems, but fat appears to just be a scapegoat.  Fats, including some saturated fats (like the kinds in milk), are extremely beneficial for hormone regulation, and therefore recovery. 

So when it comes to choosing between milk for recovery, I suggest full-fat chocolate milk.  If you are however, looking to watch your calorie intake, I first suggest eliminating the extra calories in the form of artificial sweeteners in the chocolate milk—so go with white, whole milk, in this situation.  And although you may be gaining some extra calories from this fat initially, you will be recovering better, and feel more satiated from the fat content for longer, making it easier to decline other foods later on.

As far as other supplements are concerned, none work as well as whole, minimally processed foods.  As I do understand your diet may not always be ideal, I do suggest a complete multivitamin taken daily.  I know in this specific case we’re talking about a 120 lb. high school female, so I would just suggest maintaining a high level of protein intake (making sure to get a full serving of protein-rich food per meal), which can be a large problem with the young, female demographic.


As far as other nutrients, vitamins, minerals, and the fiber you need will come naturally with a healthy diet. And as I stated earlier, we can’t really vilify anything, a good balance of healthy fats, proteins, and carbohydrates will be a huge key in injury prevention, recovery, well-being, and your athletic success.

Written by John Matulevich a powerlifting world record holder in multiple lifts and weight classes, as well as a Head D-2 Strength Coach, and previously a nationally ranked college athlete. His concentrations are in sports performance, powerlifting, and weight training for swimming. To learn more about how John trains his athletes, check his Twitter page: @John_Matulevich. He can also be reached at MuscleEmporium@gmail.com with inquiries.

Friday Interview: Dr. Vassilis Mougios Discuses Nutrition for Swimmers

1. Please introduce yourself to the readers (how you started in the profession, education, credentials, experience, etc.). 

I am Professor of Exercise Biochemistry at the School of Physical Education and Sport Science at Thessaloniki, the Aristotle University of Thessaloniki (AUTh), Greece. I am a chemist by training and did my PhD in muscle biochemistry at the University of Illinois at Chicago. I have been a faculty at the AUTh for 25 years, teaching both undergraduate and graduate students, mentoring, doing research on exercise biochemistry and physiology, as well as writing scientific papers and books.

2. You recently published numerous articles on swimming and nutrition. What do we know about swimmers and their nutrition? 
Research on swimmers’ nutrition has yielded many interesting findings. Swimmers are, in several cases, not meeting their macronutrient requirements (for example, excessive intake of fats in place of carbohydrates) or micronutrient needs (for example, suboptimal intake of iron). Nevertheless, energy intake, as a whole, seems to balance energy expenditure. Another finding is that swimmers use dietary supplements that are frequently excessive and unnecessary. 

3. What are some myths about swimmers’ nutrition?
Extremely low-energy, or crash, diets, aiming at rapidly reducing body weight, are unsafe and usually accompanied by a drop in performance. Energy intake should just be individually tailored to meet energy demands and nutrient needs of the swimmer during each training phase. If weight loss is needed or desired, energy balance should be moderately negative so as not to compromise health and hamper performance.

Dietary supplement use among swimmers is, in many cases, scientifically unjustified. Swimmers should not give in to nutritional trends before seeking advice from a qualified professional.

4. How can swimmers nutrition be improved? 
Nutritional education can help swimmers implement good dietary habits, which, in turn will help them meet their nutritional needs. The need for nutritional education targeted at athletes, their parents and coaches is often highlighted in the literature. Dietary analysis and evaluation, along with hematologic and biochemical testing, as well as anthropometric evaluation, are indispensable in order to estimate individual needs and pinpoint possible inadequacies. Regular re-evaluation should also be in order.

As a general guideline, swimmers should incorporate a great variety of foods (such as vegetables, fruits, pasta, red and white meat, dairy products, cereals and fluids) in a carefully planned daily schedule (encompassing 5-6 meals) and adapt this schedule to the particular demands of training phase and goals.


5. Many athletes are attempting a Low Carb High Fat diet, what do you think of this idea for sprint and distance swimmers? 
Such diets seem improper for swimmers from both a health and performance standpoint. Surely, sprinters do not rely on fats for success in their events. Distance swimmers use more fats (compared to sprinters), mostly during prolonged training sessions; however, these too draw more energy from carbohydrates than fats. Low carbohydrate availability, although it may facilitate some training adaptations in some cases, has not been tested in a competitive environment, more so in swimmers. Low Carb High Fat diets can have negative effects on performance, recovery, body mass, body composition, immune system and lipidemic profile of swimmers.

6. If an athlete could afford any testing or consulting on nutrition, what should they do?
They should have their diet analyzed in conjunction with hematologic/biochemical testing as a first step towards better nutrition. A qualified professional could use this information to assess possible inadequacies and suggest corrective measures. Such procedure can improve training adaptations, recovery, performance and the overall health of swimmers.

7. What supplements do you think are helpful for swimmers?
Creatine can enhance the yields of power training and performance in events relying on the ATP-phosphocreatine system. Sodium bicarbonate has been found to enhance performance in events relying on the anaerobic breakdown of carbohydrates. Caffeine has been found to enhance performance in events lasting longer than 4 minutes by decreasing the rate of perceived exertion. Nitrates have been found to increase exercise economy, although data on swimming performance are scarce. Sports drinks (containing carbohydrates and electrolytes) are suggested during training and prolonged events to prevent carbohydrate depletion and dehydration. Micronutrient (such as iron and magnesium) or macronutrient supplements (such as carbohydrate and protein) can be helpful in cases of inadequate or imbalanced nutrition. Supplements should only be used under expert supervision and should be tailored to the specific needs of the swimmer. Always bear in mind that supplements are, well, supplements; they can’t substitute for a well-balanced diet.

8. How should supplement use be improved in swimming?
Primarily, through nutritional education of swimmers, their parents, and coaches. All these should be thoroughly informed about best nutritional practices, optimal food selection, as well as the pros and cons of the various supplements on the basis of available scientific evidence. Second, through the implementation of dietary analysis and hematologic/biochemical testing in order for inadequacies to be spotted and remedied. An expert on sport nutrition should always be the one to recommend supplements and the way they should be used. Adverse health effects or doping outcomes are a real danger of sloppy supplement use.

9. If someone is on a budget, what are the easiest nutritional tips for elite swimming performance?
A wide variety of foods can improve a swimmer’s dietary status and performance. Foods that are inexpensive in most countries can easily supply swimmers with all the nutrients they need. Fruits and vegetables are rich in micronutrients; pasta, rice and potatoes are rich in carbohydrates; chicken and dairy products are rich in proteins, minerals, and vitamins. All these foods are rather low-cost. Use the highest variety possible; it’s the best recipe against nutrient deficiency and the need for expensive supplements.

10. What are some emerging ideas/hypotheses about elite athlete nutrition? 
Nutrient timing, especially around training sessions or competition, seems to be a promising concept regarding swimmers’ nutrition. Optimal energy supply, recovery, and adaptations, all leading to increased performance, might be achieved through proper timing and control of dietary intakes.

11. What research or projects are you currently working on or should we look from you in the future?
Over the past few years, our attention has been attracted by a rather overlooked biological specimen in exercise science: urine. Our data from running and swimming studies show that urine possesses certain advantages over blood in terms of the information they provide about exercise metabolism. We plan to publish such information from swimmers’ urine analyses in the very near future. 

Swimming has also been an attractive exercise model to apply on laboratory animals. We are currently examining the effects of life-long exercise (daily swimming) on metabolism and frailty status of rats. Naturally, it would be preferable to conduct such a study on humans but this would take a lifetime (literally). In contrast, it’s easier to do it with rats that live about two years. Hopefully, the results of this study will be applicable to us humans.

Multivitamins for Swimmers? Do They Work?

Take Home Points on Multivitamins for Swimmers? Do They Work? 

  1. Multivitamin supplementation for 7 - 8 months does not increase performance.
  2. Coaches should reconsider their travel and team meals, stressing healthy options for long-term nutritional health. 

Having minimal mineral and vitamin levels is likely a prerequisite for elite performance. Many feel athletes undergoing heavy training volumes and intensities require different vitamin/mineral consumption for maximal performance. In fact, some feel it is difficult for many to maintain certain mineral and vitamin levels due to the demands of training. 

Combine this with other factors which alter vitamin/mineral levels like age, sex, season, and vitamin/mineral supplementation seems imperative.

Telford (1992) split eighty-two subjects (23 swimmers, 24 gymnasts, 21 basketball players, 14 rowers; M=49, F=32; ~18.95 years) into an experimental or control group. Both groups were supplemented with iron (ferrous sulphate) if their plasma ferritin concentrations fell below 30 ng/ml (measured throughout the study). 

The experimental groups took a daily vitamin and mineral supplementation tablets. The controls received a placebo. All participants received nutritional education. Performance tests were taken before and after the 8 week intervention. 

Vitamin and Mineral Supplementation on Body Composition

The results noted similar nutrient intake between groups. The basketball players had a significant increase in body weight for the experimental protocol. There was also a significant increase in skinfold for the supplement group of basketball players. Iron intake dropped below 100% in the control group of gymnasts. 

Vitamin and Mineral Supplementation on Performance

No significant effects of performance were measured in the swimmers, gymnasts or rowers. There was another significant improvement in vertical jump in the supplement group of basketball players. 

The diets in these athletes reached the recommended dietary intake (RDIs) for vitamins and minerals). In athletes meeting the minimum RDI did not alter performance. The weight gain in the basketball players is surprising, potentially by increasing the B6 status and increasing power development.

Supplementation in athletes already reaching RDIs of vitamins and minerals does not improve performance. However, many will question if RDI is the best method for measuring nutrient adequacy. Certainly, many methods of measuring micronutrients has improved since 1992, requiring more recent review. Also, many will agree the nutrient profile has greatly changed for swimmers (and the general population since 1992). 

No matter if achieving RDIs of vitamins and minerals occurs, coaches should strive for adequate nutrition for each of their swimmers. Also, blindly supplementing is likely a waste of money. Instead of supplementation, set a healthy nutritional plan for their future. Too often teams ignore nutrition, especially during travel, impairing their nutrition for an entire life! 

Coaches quit stressing supplement intake and stress a well-rounded diet! This implementation may not improve performance, but can increase health and weight management for a lifetime! Remember, children's brains are highly plastic, ensure you're molding them correctly!


Reference
  1. Telford RD, Catchpole EA, Deakin V, Hahn AG, Plank AW. The effect of 7 to 8 months of vitamin/mineral supplementation on athletic performance. Int J Sport Nutr. 1992 Jun;2(2):135-53.
By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the owner of COR, Strength Coach Consultant, Creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

Excess Protein Intake Does Not Increase Muscle Mass

Take Home Points on Excess Protein Intake Does Not Increase Muscle Mass

  1. Excess protein intake (4.4 g/kg) does not alter body composition
Swimmers, like all athletes and fitness enthusiast commonly consume protein powder or
copious amounts of protein. Some feel this high volume is damaging on the kidneys, but does it help build muscle and increase force production potential for swimmers? Also, what is the ideal protein intake for improvement?

Protein is an important macronutrient for positive changes in body composition. Previous studies have suggested that protein intakes in the range of 1.2-2.0 grams per kilogram (kg) body weight per day (g/kg/d) are needed in active individuals. In contrast, the US recommended daily allowance (RDA) for protein is 0.8 g/kg/d (Antonio 2014). The average amount of protein ingested for adults daily is ~1.0 g/kg ideal body weight. The average US adult consumes slightly more than the RDA; however, this level is inadequate for athletes or active individuals who engage in exercise/sport training for several hours per week (Antonio 2014). Consuming more than the RDA can be considered a ‘high’ intake of protein. Many a high protein diet greater than 15-16% of total energy intake, intakes greater than the RDA or perhaps anything that exceeds 35% of total energy intake. Studies had differed to what constitutes a ‘high’ protein diet. We would argue that using percentages as a means of defining ‘low’ or ‘high’ protein intakes is misleading. If one were to consume the low calorie diet (ex. 1000 kcal/d), a protein intake of 36% (of total kcals) would be 90 grams; in contrast, it would be 180 grams on a 2000 kcal/d (Antonio 2014).  It is best to measure protein intake per unit body weight instead of as a percentage of total energy.

Antonio (2014) investigated the effects of a very high protein diet (4.4 g/kg/d) on body
composition in resistance-trained men and women. Thirty healthy resistance-trained individuals participated in this study (age: 24.1 yr; height: 171.4 cm; weight: 73.3 kg). Subjects were randomly assigned to one of the following groups: Control (CON) or high protein (HP). The CON group was instructed to maintain the same training and dietary habits over the course of the 8 week study. The HP group was instructed to consume 4.4 grams of protein per kg body weight daily. They were also instructed to maintain the same training and dietary habits (e.g. maintain the same fat and carbohydrate intake). Body composition (Bod Pod®), training volume (i.e. volume load), and food intake were determined at baseline and over the 8 week treatment period. The HP group consumed significantly more protein and calories pre vs post. Furthermore, the HP group consumed significantly more protein and calories than the CON. The HP group consumed on average 307 grams of protein compared to 138 in the CON. When expressed per unit body weight, the HP group consumed 4.4 g/kg/d of protein versus 1.8 ± 0.4 g/kg/d in the CON. There were no changes in training volume for either group. There were no significant changes over time or between groups for body weight, fat mass, fat free mass, or percent body fat. Consuming 5.5 times the recommended daily allowance of protein has no effect on body composition in resistance-trained individuals who otherwise maintain the same training regimen. This is the first interventional study to demonstrate that consuming a hypercaloric high protein diet does not result in an increase in body fat.

This is the first study in resistance-trained individuals which demonstrates that a hypercaloric high protein diet does alter body composition. Previous studies investigating overfeeding showed gains in body weight, fat mass and lean body mass. Those studies used non-exercise-trained individuals that were consuming a lower protein diet. The subjects in the current study did not alter their training. It would be interesting to see if a high protein diet concurrent with heavy swimming or current resistance training and swimming would alter swimming performance and body composition. In the mean time, excess protein intake is not likely beneficial for swimmers, or any exerciser, so lay off the excessive protein and simply consume ~1.2 - 1.7 g/kg/d of protein.
  
References:
  1. Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. J Int Soc Sports Nutr. 2014 May 12;11:19.

By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the owner of COR, Strength Coach Consultant, Creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

Friday Interview: Aaron Hermann Discusses Doping in Sports


1. Please introduce yourself to the readers (how you started in the profession,
education, credentials, experience, etc.).
My interest in sports from a professional perspective began when I studied a course in Sports Law during my Law Masters. The issues presented, particularly relating to doping seem both interesting and concerning simultaneously. I was especially interested in the aspects of fairness, ethics and equality and how diplomacy can aid in helping to ensure sports remain sustainable. I have higher degrees in Law, International Law, Commerce, Diplomacy and Arbitration and currently working toward completing my PhD. I have been teaching at university in the areas of Business Law and Management for the last 7 years.

2. You recently published an article on performance of doping and non-doping 100-m runners. What research do we know about doping?
There has been a lot of research done in the area of doping in sport. Much of the research relates to attempts to improve doping detection, from enhancements of older techniques to novel approaches to detection. There is also much work on determining if a particular agent is performance enhancing or not. Others still concern the legal and ethical problems related to the current anti-doping systems and general discussions of reasons for anti-doping. Sociological and historical analyses are also quite common.

3. You mention conflicting evidence on the effects of doping in sports. Is there a reason why we don't have concrete evidence on doping, especially anabolic agents?
This relates to the clandestine nature of doping. Because doping is forbidden, and in many countries a criminal act, the practice is very much underground and so reliable information is difficult to come by. Particularly for athletes, this means that if they want to resort to doping, they would be experimenting with different substances in different ways and as such will have different apparent effects on their performance and health. Academic research is performed on numerous substances, but it is incomplete and simply cannot investigate every agent in existence. Similarly different techniques for investigating agents will inevitably result in differing results.

4. What were the results of you study?
The way doping is practiced, particularly because of the lack of reliable information about the effects of doping and the hidden nature, means that athletes need to experiment. It seems that the ways they are experimenting has random results on performance, and as such the overall performance of doped and non-doped athletes does not differ significantly. This does not mean that all doping is ineffective for performance enhancement, historical examples have shown that scientifically supported and controlled doping does indeed work but rather experimentation has its down sides. Moreover, doping is far more widespread than anti-doping statistics would indicate, it would seem that a larger number of athletes are doping than are being caught.

5. What are some of the theories for doping not improving 100-m performance?
Experimentation; the lack of clear effects of doping agents and which techniques or amounts to use mean that athletes would need to randomly rely somewhat on luck. Especially because of the hidden nature of doping, so athletes simply do not have full knowledge of the effects. Also there are a number of different aspects of sprinting, not just strength, but also reaction time, and so to target many different aspects of performance, many different agents will need to be combined. This could result in any number of unexpected consequences and results to both health and performance.

6. Some will disagree with your suggestions in this paper, as some feel doping obviously makes 100-m runners faster (ie Ben Johnson), what do you saw to these thoughts?
There is definitely some evidence that shows that doping does work for performance enhancement, not just in sprinting but also cycling, shot-put and a number of other sports. Historical evidence, such as with East Germany, demonstrate the enhancement possibilities available. The problem that exists in some sports and with some athletes is the lack of clear information and support. Situations where it is still scientifically supported would probably result in positive enhancement of results. But if athletes are randomly experimenting, then the effects will be unknown. This would, however, indicate that athletes in some cases are still being supported by unethical sports scientists or medical practitioners, and that anti-doping legislation is less effective than desired.

7. In your study, you also say these results may be very sport specific, can you speculate about doping in swimming?
If you look at the WADA laboratory statistics for aquatics, it can be seen that the adverse analytical findings of doping in aquatics are a little bit lower than athletics. To think that doping is not happening in any sport is unreasonable, it no doubt still occurs. Not all athletes are willing to compete on a level playing field and will take anything to get the advantage. There have been recent scandals in Australia with swimming and the use of sleeping pills, whilst not in the same category as doping; some may say that because they are being abused to help athletes sleep it may still constitute an unfair act. So it is difficult to know exactly the levels, but it no doubt still occurs.

8. Do you think doping regulations or monitoring could be improved, if so how?
Yes anti-doping policies need considerable work. The current system revolves around chemical testing and punishment. There is considerable evidence out there that the chemical testing is either simply not detecting everything or athletes are just adjusting their doping regimes to accommodate the testing realities. Most athletes are not stupid and so are quite capable of learning and changing their practices to avoid testing positive. Similarly, many of the punishments are not effective, either because they fail to target the cost-benefit ratio (the benefits of doping outweigh the punishments) or they fail to address the true cause of the doping. There are numerous realities of the world of sports, expectations by spectators, managers and coaches all put pressure on the athletes to perform at a level that, in some cases, is unstainable without resorting to other techniques, and some may resort to doping to help cope. Changes to the anti-doping systems need to address the problems and causes triggering doping, not just punishment after the doping scandal comes to life. In essence less stick more carrot. Athletes’ perspectives and psychologies need change, there needs to be social changes in the way sports operate and athletes make decisions. Athletes need to decide themselves not to dope, policies should not just try to scare them into not doping.

9. What research or projects are you currently working on or should we look from you in the future?
I am currently looking at alternatives to the current anti-doping systems, that target not just punishment but rather social changes to the sporting system and the ways in which sports are viewed. For example investigations into the ethical, social and psychological aspects of anti-doping from all stakeholders in sport. More generally new approaches to prevent doping scandals before they occur.

Low Bone Mineral Density in Swimmers is Caused by Magnesium Deficiency?

Take Home Points on Low Bone Mineral Density in Swimmers is Caused by Magnesium Deficiency?

  1. Low magnesium levels predicted low bone mineral density and lean soft tissue in elite Portuguese swimmers
  2. Adding 100 mg of magnesium a day improved these levels
Nutrient and supplements are a huge market for athletes. Swimmers (the small market we are) even have our own supplement line targeting swimmers. Now, proper nutrition and a well-balanced diet are essential for success, but how do you know what to take and how much? 

Individualized nutritional and supplement programs are ideal, as everyone consumes and metabolizes food differently. If looking for the top advice, have some blood work, then consult a physician or nutritionist on your deficiencies. Now, which blood markers influence performance is not well understood (vitamin D deficiencies are often low, but may not influence performance), but adequate nutrient levels likely influence long-term health.

In swimmers, bone mass and muscle mass are important considerations due to the lack of joint loading. Magnesium (Mg) appears influential on bone mineral density (BMD). It is estimated that 1300 g of calcium, 14 g of Mg and 60 g of phosphorus in bones of a 70 kg human (154 – pound human) (Synder 1975). Therefore, understanding the influence of Mg on bone and lean body mass an essential consideration for athletes.

Matias  (2012) had seventeen elite swimmers (M=8, F=9; ~16.6 years; Sprinters=6, Middle distance=9, Distance=3) from Lisbon with at least:
1)    Minimum period of activity of approximately six years
2)    > 10 hours training per week
3)    Negative test outcomes for performance enhancing drugs
4)    Not taking any medications or dietary supplements

All the swimmers underwent body composition testing (BOD POD), dual energy x-ray absorptiometry (DEXA), recorded energy and nutrients for a seven day period.

Males had significantly lower bone mineral density than normative values. Mg, P, and vitamin D intake were significantly lower than the recommended daily allowances. Mg values were a predictor of lower bone mineral density. There was also a direct correlation between bone mineral density and lean soft tissue (muscle mass).

Magnesium and Bone Mineral Density

Mg correlates with BMD and lean soft tissue (LST). In fact, this study suggests that Mg intake explains an additional 24% of BMD than LST by itself.

If these calculations are accurate, adding 100 mg of Mg a day would increase BMD by 0.259 g/cm2, providing normative values.

Practical Implication for Swimmers

Young swimmers should consume foods high in minerals. If low in magnesium, consider adding dark leafy green vegetables and nuts into the diet. However, extrapolating this data blinding is a flaw, as individual nutrition and guidelines are mandatory for cost efficient, effective nutritional and supplement recommendations.

 References

  1. Snyder WS, Cook MJ, Nasset ES, Karhausen LR, Howells PG, Tipton IH. Report of the Task Group on Reference Man: a report. Oxford:Pergamon Press, 1975.
  2. Matias CN, Santos DA, Monteiro CP, Vasco AM, Baptista F, Sardinha LB, Laires MJ, Silva AM. Magnesium intake mediates the association between bone mineral density and lean soft tissue in elite swimmers. Magnes Res. 2012 Jul-Sep;25(3):120-5. doi: 10.1684/mrh.2012.0317.


Written by G. John Mullen who received his Doctorate in Physical at University of Southern California (USC) and is a certified strength and conditioning specialist (CSCS). At USC, he was a clinical research assistant performing research on adolescent diabetes, lung adaptations to swimming, and swimming biomechanics. G. John has been featured in Swimming World Magazine, Swimmer Magazine, and the International Society of Swim Coaches Journal. He is currently the owner of COR, providing Physical Therapy, Personal Training, and Swim Lessons to swimmers and athletes of all skills and ages. He is also the creator of the Swimmer's Shoulder SystemSwimming ScienceSwimming Science Research ReviewMobility System and the Swimming Troubleshooting System.