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Nutrition for Sport Performance: Part 2


Part 1 of this article series, Nutrition for Sport Performance: Part 1, explored findings from current literature that have been determined to effectively, safely, and legally increase the body’s natural production of anabolic hormones. Part 1 also discussed the importance of nutritional timing for athletes that enhances body composition for improved sport performance. This article reviews specific foods and supplementation found in current literature that have been determined to effectively, safely, and legally increase the body’s natural production of anabolic hormones, and facilitate changes in body composition in attempt for athletes to improve sport performance.

Learning Objectives:

  1. Review specific foods that have proven to directly or indirectly increase protein synthesis, decrease fat mass, or influence the mechanisms of both.
  2. Describe several supplements that are recommended for any athlete training at high intensities.
  3. Consider ideas for future research in regard to maximally effective dosages of supplementation.

Specific Foods to Enhance Body Composition

The following foods have proven to have some beneficial effects for directly or indirectly increasing protein synthesis, decreasing fat mass, or influencing the mechanisms of either. For example, cinnamon and vinegar both help to lower overall blood sugar. If blood sugar is lowered at a time unrelated to exercise, less insulin will be present during digestion, and therefore there will be less potential for adipose tissue accumulation.   

Blueberries/Grape juice. Intense training is known to induce damage to contractile and connective tissue components in muscle fibers; resulting in impaired muscle function, increased inflammation, pain, swelling/edema, and possible leakage of myofibril proteins. Foods high in antioxidants have been shown to effectively reduce the amount of oxidative stress after intense exercise. Blueberries contain the broadest range of antioxidant compounds among berry-fruits and when consumed before or after a workout they play a pivotal role in countering free-radical activity within the body, helping to minimize muscle soreness, while accelerating the recovery of muscle strength (McLeay, Barnes, Mundel, Hurst, Hurst, & Stannard, 2012). 

Grape juice has also been shown to continuously exert persistent antioxidant activity beyond two hours after consumption, whereas other fruits high in antioxidants only scavenged free radicals for up to 90 minutes post-consumption (Ko, Choi, Ye, Cho, Kim, & Chung, 2005). Therefore, consuming grape or blueberry juice will not only help to trigger an insulin response post-exercise, but it will also help with recovery as the antioxidants help decrease muscle damage from free-radicals.

Red Meat. Red meat is often demonized because of its high saturated fat and cholesterol content. In a meta-analysis evaluating the association between saturated fat intake with cardiovascular disease, it was concluded there is no increased risk of cardiovascular disease due to saturated fat intake and quite possibly the risk factors could be influenced by other ingredients typically substituted for saturated fat in many foods (Siri-Tarino, Sun, Hu, & Krauss, 2010). Recent research has also proven that dietary cholesterol is not correlated to serum cholesterol - dietary cholesterol intake is absolutely necessary for optimal gains in lean muscle mass and strength. In a study with men and women 60-69 years old who partook in 12 weeks of resistance training, protein intake was equal among all participants, but significant increases in strength and muscle mass were observed in a dose-response for individuals who had higher dietary cholesterol intakes.  Serum cholesterol was also positively associated with greater increases in lean mass, suggesting that cholesterol is a necessary mediator for muscle growth as it aids in the production of the sex hormones testosterone (Te) and estrogen (Riechman, Andrews, MacLean, & Sheather, 2007).

Vegetarian diets are often very low in cholesterol as everything is plant-based. When men were fed a vegetarian diet for two weeks, the nocturnal release of prolactin, luteinzing hormone (LH), and Te all subsequently decreased (Hill & Wynder, 1979). Prolactin is best known for the stimulation of lactation in women; but in men the concentration of plasma Te is dependent on both LH and prolactin as they seem to have a stimulatory effect on Te secretion by influencing Leydig cell activity (Rubin, Poland, & Tower, 1976). In another study comparing metabolism and hormones in men who were either omnivores or vegetarians, the vegetarians had less Te available for androgenic actions (Bélanger, Locong, Noel, Cusan, Dupont, Prévost, & Sévigny, 1989). When endurance athletes were put on either a vegetarian diet or a meat-rich diet for six weeks, the vegetarian group noticed a reduction in Te levels, although exercise performance was not significantly different in this study (Raben, Kiens, Richter, Rasmussen, Svenstrup, Micic, & Bennett, 1992). Vegetarians also tend to have less overall intra-muscular creatine stores and a greater risk for iron deficiency due to a lack of meat in the diet, which may adversely affect athletic performance (Venderley & Campbell, 2006).

When considering the kind of meat to consume, organic grass-fed meat is the best option as it tends to have much less saturated fat with considerably higher amounts of anti-inflammatory omega-3 fatty acids compared to factory-raised animals who are typically fed genetically-modified corn laced with hormones and antibiotics, which contain more pro-inflammatory omega-6 fatty acids (Lucan, Fretts, Howard, & Siseovick, 2012). 

Grass-fed beef has other benefits: it contains higher amounts of conjugated linoleic acid (CLA) compared to factory-raised beef. CLA is naturally found in dairy and beef foods, and also in hydrogenated vegetable oils. The two main isomers of CLA are cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) CLA, with c9,t11 being the predominate isomer in normal diets (Risérus, Vessby, Ärnlöv, & Basu, 2004). Consumer weight-loss products usually contain equal amounts of both isomers of CLA. In obese and overweight men and women, supplementation with 3.4g/day of a 50% c9,t11 / 50% t10,c12 solution of CLA for 12-weeks significantly reduced body fat compared to a placebo. Intakes above 3.4g/day did not further improve the effects (Blankson, Wadstein, Gudmundsen, Thom, Stakkestad, & Fagertun, 2000). In a smaller 4-week study on obese men with metabolic syndrome, a similar 50/50 solution of CLA seemed to also reduce abdominal adipose tissue as abdominal anthropometric measurements were less in the CLA group compared to a placebo, with no other adverse effects noted. Visceral fat in obese men has a greater ability to mobilize fatty acids compared to subcutaneous fat cells in response to cathecholamines, and CLA may possibly induce cathecholamine-related lipolysis (Risérus, Berglund, & Vessby, 2001). In resistance-trained males, CLA supplementation after a resistance training bout might also promote testosterone synthesis through molecular pathways (Macaluso, Morici, Catanese, Ardizzone, Marino Gammazza, Bonsignore, & Di Felice, 2012). Lastly, in an 8-week study on healthy subjects, CLA supplementation improved serum triglyceride and very-low density lipoprotein (VLDL) cholesterol concentrations, suggesting there are also some cardio-protective effects of CLA (Noone, Roche, Nugent, & Gibney, 2002).

Cinnamon. Cinnamon has long been used as an herbal medicine in other countries, whereas in America it is primarily used as a spice. Not all studies have shown beneficial effects with the use of cinnamon, but many studies have shown improvements in glucose utilization. In type II diabetics with poor glycemic control, cinnamon was shown to be effective in reducing fasting glucose levels (Mang, Wolters, Schmitt, Kelb, Lichtinghagen, Stichtenoth, & Hahn, 2006).  Other studies have shown cinnamon and its components to have positive effects on almost all factors associated with metabolic syndrome. Cinnamon seems to have insulin-potentiating properties that enhance glucose uptake, improving insulin sensitivity and therefore improving lipid serum levels, inflammation, blood pressure, and body composition (Qin, Panickar, & Anderson, 2010). In 22 pre-diabetic men and women with metabolic syndrome, supplementing with 500mg/day of a cinnamon extract for 12 weeks significantly decreased fasting blood glucose, systolic blood pressure, and increased lean mass compared to a placebo, suggesting cinnamon can reduce risk factors for diabetes and cardiovascular disease (Ziegenfuss, Hofheins, Mendel, Landis, & Anderson, 2006). 

Coconut oil. Coconut oil contains a high amount of lauric acid, of which consumption has shown favorable changes to blood lipid profiles in men and women when compared to consumption of trans-fatty acids. Coconut oil primarily consists of medium-chain fatty acids (MCFAs), which are easily oxidized lipids that get rapidly absorbed in the intestines and do not enter the cholesterol cycle or get stored in adipose tissue unlike long-chain fatty acids (LCFAs), which require pancreatic lipase for absorption (Liau, Lee, Chen, & Rasool, 2011). When consumed regularly, MCFAs have been shown to increase energy expenditure and fat oxidation compared to oils containing LCFAs (St-Onge, Jones, Parsons, & Ross, 2003). When researchers investigated the use of coconut oil on subjects with BMI’s greater than 23, it was found that consumption effectively reduced visceral adipose tissue and subsequently waist circumferences in men only. In women it actually did not show any significant difference in waist circumference, but rather it showed women lost more overall body fat than men (Liau, Lee, Chen, & Rasool, 2011).

Vinegar. In an attempt to keep insulin levels at bay during normal meals (not post-exercise), the potential for fat storage can be reduced by ingesting vinegar.  Vinegar has an anti-glycemic effect when consumed with a meal. As little as 10g (2-teaspoons) of vinegar with a carbohydrate-meal has been shown to reduce the postprandial glycemic response by 20% (Johnston, Steplewska, Long, Harris, & Ryals, 2010). It is believed to work by inhibiting some digestive enzymes, therefore reducing the rate of gastric emptying. For it to be most effective, vinegar should be consumed in the first bites of a meal. An easy application for this would be to choose a balsamic vinaigrette salad dressing to use at the beginning of a meal.   

Supplementation

While many essential vitamins and minerals can be obtained through a diverse diet, there are a few which can be depleted from exercise beyond what can easily be ingested. The following supplements are necessary for individuals to consume if they are deficient in them, making muscle gains much more difficult to achieve - not to mention the necessary amounts to increase serum levels are not easily obtained in a realistic diet.

Omega-3 fatty acids. There have been over 900 human clinical trials providing evidence for the effectiveness of fish oil and the multitude of inflammatory conditions they support. Omega 3’s mediate prostaglandins, which are hormone-like substances that improve blood flow and reduce inflammation; and exercise is no different. Researchers provided 11 subjects with 3,000mg/day of omega-3 fatty acids for one week to determine the post-exercise inflammatory response after intensive eccentric training bouts. They concluded that supplementation with omega-3’s reduces muscle soreness and pain post-exercise which is beneficial for anyone involved in high-intensity training who tends to create delayed-onset muscle soreness (Jouris, McDaniel, & Weiss, 2011). In another study conducted on older adults supplementing with either ~3,300mg/day of fish oil or corn oil; the fish oil group noticed double the anabolic signaling activity above basal rates when amino acids and insulin were infused. The researchers were not certain as to the cause of this increased muscle protein metabolism, but concluded that omega-3 fatty acids could be a very simple, safe, and affordable way to increase muscle (Smith, Atherton, Reeds, Mohammed, Rankin, Rennie, & Mittendorfer, 2011).

Vitamin D. Low circulating vitamin D concentrations have been associated with both increased fat mass and BMI among children and adults. Deficiency in vitamin D can lead to increased parathyroid hormone (PTH), which may enhance lipogenesis. Daily supplementation of vitamin D has been shown to specifically reduce visceral adipose tissue, along with improving insulin sensitivity (Rosenblum, Castro, Moore, & Kaplan, 2012). The majority of cross-sectional studies researching the effects of dairy indicate a positive relationship between consumption and body weight/composition in both children and adolescents, with lower intakes associated with increased risk for cardiovascular disease, type II diabetes, and poor bone health (Spence, Cifelli, Miller, 2011).  This may be due to the repression of the enzyme fatty-acid synthase. In a study looking at the efficacy of vitamin D supplementation in overweight and obese women, body fat mass decreased as vitamin D serum concentrations increased, along with a decrease in iPTH (intact PTH) (Salehpour, Hosseinpanah, Shidfar, Vafa, Razaghi, Dehghani, & Gohari, 2012).

Vitamin D is also necessary for muscle growth. When healthy overweight men with low testosterone (Te) levels were given ~3,300 iu/day for one year, a significant increase in total testosterone was observed when compared to baseline levels and a placebo group (Pilz, Frisch, Koertke, Kuhn, Dreier, Obermayer-Pietsch, Wehr, & Zittermann, 2011).

Zinc/Magnesium. Magnesium (Mg) is critical in the cellular events and metabolic activities influenced by physical activity, such as energy production and muscle contraction. Several studies have shown intense physical stress can deplete Mg levels through urine and sweat loss (Golf, Bender & Grüttner, 1998).  Deficiencies in Mg have been associated with a number of chronic diseases including: diabetes, hypertension, insulin resistance, vascular disease, lipid abnormalities, and depression, among other things. Simply increasing Mg intake has been shown to improve all of the aforementioned conditions.

In a recent cross-sectional study involving 210 diabetics 65 years and older, daily nutritional Mg intake did not meet the DRI for 89% of the participants, which was thought to be indicative of common deficiencies in the general population. Intake levels were positively associated with serum HDL levels and physical activity levels, and showed an inverse relationship with serum triglycerides, body fat percentage, and body mass index (Huang, Lu, Cheng, Lee, & Tsai, 2012). 

Zinc and Mg supplementation have also been correlated to increased IGF-I levels. Zinc specifically can increase serum Te concentrations; in trained football players, zinc and Mg supplementation improved muscle function along with the anabolic hormone profile after seven weeks of training (Brilla & Conte, 2000).  Brilla & Haley (1992) investigated Mg supplementation alone among subjects and found significant gains in strength among the Mg group compared with a control group. The researchers believe Mg acts at the ribosomal level during protein synthesis. In competitive triathletes supplementing with Mg for four weeks, they noticed an increased overall work capacity, along with decreased levels of cortisol before and after exhaustive exercise, indicating the improvement in efficiency compared to a control group (Golf, Bender & Grüttner, 1998).

Discussion: Individualization

Every exerciser/athlete will respond slightly different to nutritional intervention strategies; what works for some individuals may not for others. Even in a lab setting where things are "controlled," there are still factors and variables that cannot be completely controlled - lending the possibility for different results.  Therefore, the focus should be to track and monitor the exerciser's/athlete's performance along with how they feel when attempting to make dietary changes for the sake of improving body composition or sport performance. All too often exercisers/athletes, coaches, and trainers fail to continually conduct assessments to determine if their nutritional interventions are working and ,if so, by how much. Tracking body composition along with relevant sport performance statistics is essential to determine what the best strategy is for each individual. 

Future Research

Some of the current research utilized specific amounts of dosages - in terms of supplements or specific food amounts - to investigate positive changes. Once a supplement or food source seems to get a reputation for having positive effects, whatever it may be, consumers may tend to blow it out of proportion and quickly put it on a list of "super-foods." As food science improves,it may very well reveal that these foods are powerhouses, but research should first seek to explore different dosages in different populations (for example healthy vs. obese individuals) to determine more concrete maximal effective dosages, possible thresholds of safe usage, and dosages for optimal gains. For example, there is not currently a commonly agreed upon amount of omega-3 supplementation recommended for daily consumption. Most recommendations are based on anecdotal evidence by which individuals increase their intake to a point where they stop seeing changes. Some extreme recommendations suggest taking a mega-dose of 1g of omega-3’s/percent body fat/day. Therefore, if someone is 30% body fat, theoretically they should need 30g of daily omega-3 fatty acids. While this approach may work for some individuals who are obese, future research should seek to determine if long-term use at such a mega-dosed level is safe and for what populations they may benefit most - along with differences that may exist among those populations.

Conclusion

The endocrine system controls the physiological functions in the body through the interdependent actions of different hormones and enzymes. Many individuals are tempted to administer exogenous hormones in attempt to grow muscle, improve body composition, and help post-exercise recovery. This article referenced current literature to determine proven nutritional strategies that effectively increase the body’s natural production of the hormones responsible for building muscle and decreasing fat, as well as improving exercise recovery.

When it comes to improving body composition and subsequently exercise performance, the main take away points are as follows:

1. The timing of consumption of food or supplementation is equally as important as what is consumed.
2. Ingesting appropriate amounts of amino acids and carbohydrates before, during and after workouts can help to minimize protein breakdown, while maximizing protein synthesis rates.
3. Specific foods should regularly be consumed to optimize the body’s anabolic hormones, combined with supplementation of omega-3’s, vitamin D, and zinc/magnesium to help promote muscle building, fat burning, and improve insulin sensitivity, which all safely improve exercise performance.

References

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Hill, P., & Wynder, E. (1979). Effect of a vegetarian diet and dexamethasone on plasma prolactin, testosterone and dehydroepiandrosterone in men and women. Cancer Letters, 7(5), 273-282.

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