Sports Nutrition

Sports Nutrition
by Elizabeth Srejic

Sports nutrition products, a major category within the natural products industry, help physically-active consumers achieve better body composition and optimal performance through supplementation with a wide range of ingredients delivered in an equally diverse array of forms.

Whether they’re multi-million-dollar athletes competing on the professional playing field or gym rats slogging through their usual routine at the local fitness center, athletes far and wide know nutrition is directly and inextricably linked to performance and physical results. Armed with this knowledge, physically active individuals looking for results often enlist dietary supplements as strategic weapons to attain their fitness goals. The natural products industry has responded with a plethora of products designed to burn fat, build muscle, boost performance, and banish oxidative damage and immunosuppression associated with physical exercise.

Perhaps the best-known base product in the sports nutrition category is protein. As the main building blocks of lean body mass, protein supplements are a typical component of many training programs. Protein contains amino acids, which, in addition to building and repairing tissues, help to form antibodies involved in immunity, play roles in enzymatic and hormonal systems, build nucleoproteins (RNA and DNA) and form structural components of the energy molecule adenosine triphosphate (ATP). Supplemental protein can be either vegetable-sourced or animal (generally, dairy) derived.

In addition to providing the protein macronutrient, soy protein also has antioxidant activity, useful for quenching free radicals generated during physical exertion. In a four-week comparison of soy protein and whey protein, researchers from Ohio State University, Columbus, randomly administered 40 g/d of soy protein or 40 g/d of whey protein to recreationally trained, young adult women.¹ Test subjects’ serum was drawn prior to and subsequent to moderate-intensity weight resistance exercise sessions before and after the four-week test period. Soy consumption, but not whey intake, increased test subjects’ pre-exercise serum antioxidant status and decreased post-exercise blood levels of peroxides and creatine kinase (toxins produced through oxidative stress). A study on the impact of soy protein consumption versus whey protein intake on total antioxidant status of 20 healthy, athletic, college-aged males found supplementation with 40 g/d soy protein (as Supro®, from The Solae Co.) in conjunction with a strenuous training program produced an increase in total antioxidant status as well as reduced serum levels of myloperoxidase, an indicator of oxidative stress.² In addition to its actions against exercise-related oxidative stress, soy protein also has cholesterol-lowering and cancer-fighting benefits; an American Heart Association (AHA) review of 22 randomized trials found isolated soy protein, as compared with other proteins, decreased low-density lipoprotein (LDL) cholesterol concentrations in test subjects.³

When combined with a resistance training program, whey protein has been shown to increase muscle mass and muscle strength;^4,5 enhance muscle glycogen uptake,⁶ heighten oxygen-carrying capacity of the blood and encourage quicker recovery from muscle fatigue, promoting increased training efficiency.^7,8 Whey protein is an excellent source of branched-chain amino acids (BCAAs); these basic building blocks, including leucine, isoleucine and valine, are particularly conducive to muscle growth and regeneration as they increase the rate of protein synthesis and decrease the rate of protein degradation in human muscle.^9,10,11

Whey protein may also boost immune response in athletes whose immunity has been compromised by strenuous, prolonged exercise.^12,13 Brazilian research on the impact of BCAA supplementation on immunity of triathletes and long-distance runners found BCAAs restored the ability of peripheral blood mononuclear cells to proliferate in response to mitogens and modified the pattern of cytokine production, encouraging a “Th1 type” immune response following a prolonged, intense bout of exercise.¹⁴

Casein has also shown better results than soy protein on lean muscle mass in a handful of clinical trials. One such study, completed at Maastricht University, the Netherlands, compared the efficacy of casein and soy protein with regard to the ingredients’ metabolic effects in healthy human subjects and found casein produced greater net protein synthesis in test subjects than soy; in addition, a significantly larger portion of soy protein than casein was degraded to toxic urea within the body.¹⁹ Similarly, another study out of Maastricht University measuring net protein retention and amino acid and urea kinetics in gut, liver and muscle of pigs given casein or soy found casein promoted greater net protein synthesis than did soy, while soy protein produced higher levels of urea.²⁰

Beyond compound protein sources, athletes often supplement with isolated amino acids to support their training regimens. Glutamine, the most abundant amino acid in the body, is converted to glucose during exertion, providing fuel for the musculoskeletal and immune systems. Several clinical trials have shown supplemental glutamine may decrease incidence of illness in endurance athletes who incur increased risk of infection caused by rigorous, prolonged exercise.^21,22,23 A study on glutamine supplementation among middledistance, marathon and ultra-marathon runners, elite rowers and sedentary controls showed glutamine intake following exhaustive exercise appeared to reduce the incidence of subsequent infections.²⁴ The researchers noted the ratio of T-helper and T-suppressor cells appeared to be elevated in those who received glutamine, compared with placebo.

Although exercise produces physiological benefits, it also results in oxidative damage and immunosuppression through build-up of toxins; decreased helper/suppressor T-cell ratio, salivary levels of immunoglobulin-A, lymphocyte proliferative response and natural killer cell activity; and elevation of stress hormones.⁴² Both prolonged steady-state exercise and high-intensity bursts of energy overwhelm the body’s capacity to detoxify reactive oxygen species (ROS), which can damage cell structures.⁴³ One way to counteract oxidative damage is through intake of antioxidant vitamins and minerals, which inhibit oxidative stress to organs, muscles, blood and other areas of the body.⁴⁴

Two vitamin antioxidants of benefit to physically active individuals include vitamin E and vitamin C. A randomized, double blind, placebo-controlled Japanese study in 14 male runners found vitamin E supplementation attenuated increases in serum markers of oxidative damage following a sudden intensification in training; in particular, vitamin E inhibited build-up of creatine kinase and lactate dehydrogenase following six successive days of endurance running.⁴⁵ The researchers concluded vitamin E most likely inhibits free-radicalinduced muscle damage caused by prolonged exercise. Another way vitamin E inhibits oxidative stress in athletes is through suppression of low-density lipoprotein (LDL) cholesterol oxidation associated with strenuous endurance exercise, according to a review out of Tokyo Medical University.⁴⁶ On the immunity front, vitamin E may substantially increase circulating neutrophils in physically active individuals who have sustained oxidative damage to muscles caused by eccentric bouts of exercise.⁴⁷ And, beyond its actions against exercise-related oxidative damage, LDL oxidation and immunosuppression, vitamin E may also enhance endurance, according to Ohio State University-based studies on sled dogs.^48,49

Vitamin C is implicated in a number of biochemical pathways important to exercise metabolism and health in active individuals.⁵⁰ A placebo-controlled Spanish study found vitamin C supplementation of volunteer endurance athletes participating in a duathlon competition increased erythrocyte antioxidant enzymes and plasma antioxidant levels during athletic competition and short-term recovery, while athletes given placebo experienced increases in serum markers of oxidative stress, including uric acid and lactate dehydrogenase.⁵¹ The researchers concluded vitamin C supplementation defends against oxidative stress and prevents negative exercise-related effects on erythrocyte integrity. A clinical trial testing whether two weeks of vitamin C supplementation promoted recovery in 16 men who completed an unaccustomed bout of exercise (a 90-minute intermittent shuttle-running test) 14 days after supplementation began found vitamin C produced modestly beneficial effects on muscle soreness and function, and plasma concentrations of malondialdehyde.⁵² And a Taiwanese study linked insufficient vitamin C status to low serum concentrations of lipid peroxides and increased muscle damage in female weightlifters undergoing intensive resistance training.⁵³

Levels of the antioxidant enzyme superoxide dismutase (SOD), a potent, endogenous free-radical scavenger, increase in response to exercise-induced oxidative stress.⁵⁴ Taking exogenous SOD may help to ensure plasma SOD levels sufficient to counteract free-radical damage caused by physical activity. A four-week Korean clinical trial evaluated the influence of an oral preparation of 1,500 IU/d of SOD (as GliSODin®, from P.L. Thomas & Co.) on blood antioxidant profiles and plasma lactate levels following strenuous exercise and found SOD positively affected the distribution and mobilization of human antioxidant enzymes and reduced lactic acid build-up.⁵⁵ Another study, conducted at the Nippon Medical School in Japan, administered 300 mg/d of SOD (as GliSODin) to eight healthy individuals for six days prior to intense exercise and found SOD prevented the increase in glucose consumption during strenuous physical activity that is directly related to the accumulation of lactate in the blood.⁵⁶

Other antioxidants of particular benefit to athletes include the carotenoid astaxanthin and the vitamin-like compound coenzyme Q10 (CoQ10). In a clinical trial conducted at the Kyoto Prefectural University of Medicine in Japan, scientists examined the impact of astaxanthin supplementation on oxidative damage induced by strenuous exercise in mouse calf muscle and heart, and found the carotenoid reduced markers of oxidative damage (4-hydroxy-2- nonenal-modified protein, 8-hydroxy-2’- deoxyguanosine, creatine kinase and myeloperoxidase) in gastrocnemius, heart and plasma.⁵⁷ They concluded astaxanthin can attenuate exercise-induced damage in mouse skeletal muscle and heart, including an associated neutrophil infiltration that induces additional damage.

CoQ10, an endogenous antioxidant involved in mitochondrial production of adenosine triphosphate (ATP, an energy molecule), is a particularly useful cardioprotective agent.⁵⁸ In athletes, blood levels of CoQ10 decline during a severe training period.⁵⁹ In a double blind, crossover study of 25 top-level cross-country skiers, Finnish scientists discovered CoQ10 supplementation improved all measured indexes of physical performance including aerobic exercise training (AET), anaerobic exercise and VO2 max (the maximum amount of oxygen in milliliters one can use in one minute per kilogram of body weight).⁶⁰ And a review of studies involving CoQ10 supplementation and physical exercise from Alfred Hospital and Baker Institute, Melbourne, Australia, found six clinical trials showed CoQ10 produced a modest improvement in exercise capacity, although five trials showed CoQ10 produced no effect.⁶¹

Requirements for B vitamins including B1 (thiamine), B2 (riboflavin), and B6 (pyridoxine, pyridoxal and pyridoxamine) may be heightened in athletes. Reasons for this exercise-induced increase in B vitamin requirements may include stress on metabolic pathways involved with these vitamins, decrease in absorption, increase in turnover, increase in metabolism, increased levels of mitochondrial enzymes that require the nutrients, or increased tissue maintenance and repair.⁶² One B vitamin with a specialized role in athletes is niacin (B3), which is involved in carbohydrate metabolism. Australian researchers at the Deakin University in Burwood found niacin possibly improved release of energy from carbohydrates during cycling in unconditioned women by increasing glycogen utilization.⁶³

Mobilization of B vitamins is regulated partially by magnesium, which is also involved in neuromuscular, cardiovascular, immune, metabolic and hormonal functions related to physical performance.⁶⁴ Deprivation of the mineral through physical exercise or marginal dietary intake may impair metabolic efficiency and the capacity for physical work,⁶⁵ increase the need for oxygen requirements and reduce endurance.⁶⁶ Another reason for athletes to supplement with magnesium is the mineral is lost in nutritionally significant amounts in sweat.⁶⁷

The mineral iron helps to reverse exercise-related immunosuppression through its effects on NK-cell activity, T- and Bcell functions, and cytokine release.⁶⁸ Insufficient iron status is a factor in iron-deficiency anemia, a cause of severe fatigue; the condition occurs more frequently in female athletes, possibly due to menstruation;⁶⁹ exercise-induced menstrual dysfunction can be alleviated through iron supplementation, according researchers from the University of Oregon, Corvallis.⁷⁰ Runners are another group particularly prone to low serum iron concentrations; a University of Freiberg, Germany, study in 747 athletes and 104 untrained controls found the high-impact movement of running might trigger the destruction of red blood cells and ferritin levels were particularly low in runners.⁷¹

Another trace element required for optimal athletic performance is zinc, a component of more than 300 enzymes involved in various physiological processes. In athletes, zinc is important for bone synthesis,⁷² correction of exercise-induced immunosuppression⁷³ and protection against the effects of increased free ROS resulting from exercise.⁷⁴ A randomized, placebo-controlled, four-week Selcuk University (Konya, Turkey) study on zinc supplementation in wrestlers found individuals administered zinc during the test period had increased erythrocyte, leukocyte and thrombocyte counts, and higher hemoglobin values, leading the researchers to conclude zinc supplementation may have a positive effect on hematological parameters in athletes.⁷⁵

The mineral chromium, a regulator of insulin-mediated glucose, amino acid and fat transport, is valued for its positive effects on body composition, including reduction in fat mass and increase in lean body mass.⁷⁶ An eight-week in vivo study conducted on 20 overweight women administered 600 mcg/d of niacin-bound chromium (as ChromeMate®, from InterHealth Nutraceuticals) or placebo in a randomized, crossover, double blind design indicated chromium supplementation significantly increased fat loss and spared muscle mass.⁷⁷ Chromium’s popularity in sports nutrition also stems from its alleged ergogenic qualities.⁷⁸ For example, in a study involving elite cyclists and chromium (as ChromeMate), researchers observed improved exercise performance as measured by power output among the athletes.⁷⁹ And a proprietary study conducted by Nutrition 21 and researchers from the University of Vermont Medical College, Burlington, and presented at one of the Scientific Sessions of the American Diabetes Association, showed chromium picolinate (as Chromax®, from Nutrition 21) improves strength and endurance by down-regulating tumor necrosis factor alpha and ubiquitin proteins involved in carbohydrate metabolism.

Wear and tear of rigorous exercise can result in stiffness, pain, inflammation and loss of function in joints, tendons, ligaments and other cartilaginous areas within the body. In particular, connective tissue of the knee is frequently injured in athletes, especially those involved in contact sports.^80,81

Two supplements taken to help counteract knee and other joint damage include glucosamine, an amino sugar believed to promote cartilage formation and repair, and chondroitin sulfate, a component of proteoglycans, or proteins responsible for elasticity in cartilage.

In a University of Western Australia (Crawley) study investigating the ability of glucosamine to alleviate knee pain and restore motion in cases of exercise-induced cartilage injury, 46 subjects were randomly assigned to receive 2,000 mg/d of glucosamine or a placebo over 12 weeks.⁸² Some degree of improvement in knee pain was reported by 88 percent of the glucosamine group compared to only 17 percent in the placebo group. Another knee study, conducted at University Hospital Zurich in Switzerland, suggested chondroitin sulfate may decrease pain and improve function in joints.⁸³ Two groups of subjects with symptomatic knee osteoarthritis were randomized to receive either 800 mg/d chondroitin sulfate (n=60) or placebo (n=60) for two three-month periods during one year. Subjects reported a decrease in joint pain and an increase in range of motion, while radiological progression revealed significantly decreased width in the medial femoro-tibial joint space on weight-bearing X-rays of both knees.

The efficacy of glucosamine and chondroitin in the treatment of knee pain was confirmed at two recent studies presented at an Annual Scientific Meeting of the American College of Rheumatology (ACR). In the first study, the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT), researchers from more than a dozen U.S. health care facilities compared the effects of 500 mg/d glucosamine hydrochloride, 400 mg/d sodium chondroitin sulfate (as CSb™ BioActive, from Bioiberica S.A.), both of these treatments administered simultaneously, 200 mg/d celecoxib (a drug used to relieve arthritis symptoms) and placebo, on patients with knee pain; the researchers found the combination of glucosamine and chondroitin sulfate was the most effective in relieving severe knee pain, aiding almost 80 percent of study participants, and was well tolerated.⁸⁴ In the second study, Glucosamine Unum In Die Efficacy (GUIDE), researchers compared the effect of 1,500 mg/d glucosamine sulfate, 3,000 mg/d acetaminophen and placebo on various pain and mobility indices in 318 osteoarthritis patients 24 weeks, and found glucosamine sulfate was efficacious in reducing scores on various osteoarthritis symptom indices.⁸⁵

Another ingredient of possible benefit to athletes looking to protect their joints and reduce joint pain is collagen hydrolysate. Collagen, a structural protein lending strength and flexibility to the joints, muscles and tendons, may protect articular cartilage from degradation and boost collagen synthesis. In particular, the high collagen content of ligaments makes them particularly vulnerable to exercise-related viscoelastic damage.⁸⁶ A cell culture study indicates the addition of collagen hydrolysate to mature chondrocytes leads to as much as a 2.5-fold dose-dependent increase in the secretion of collagen, suggesting the compound could induce the formation of new cartilage tissue.⁸⁷ And a review of literature on collagen hydrolysate metabolism noted ingestion of 10 g/d of collagen hydrolysate reduces pain in patients with osteoarthritis of the knee or hip, and is associated with minimal adverse effects.⁸⁸

Various botanicals are believed to assist athletes, chiefly by increasing energy and protecting tissues against damage. One such botanical is extract of French maritime pine bark. In a California State University study, 24 recreational athletes received either 200 mg/d French maritime pine bark extract (as Pycnogenol®, from Natural Health Sciences) or placebo for one month in a double blind, crossover design.⁹¹ Composite endurance scores for two groups of individuals given pine bark extract increased by a statistically significant 21 percent compared to placebo.

Another botanical, forskolin, the root extract of Coleus forskohlii, a member of the mint family, has been studied for potential ability to optimize body composition through fat reduction and support of lean muscle mass. Forskolin (as ForsLean®, from Sabinsa Corp.) may reduce body fat by stimulating 3’5’adenosine monophosphate (AMP), a compound involved in the release of fatty acids from adipose tissue, leading to improved thermogenic response and increases in basal metabolic rate and body fat consumption. A twomonth study in six overweight women administered 500 mg/d forskolin (as ForsLean) suggested the botanical caused appreciable decrease in body fat content and an increase in lean body mass.⁹² And a randomized, double-blind, placebo-controlled study conducted at the University of Kansas, Lawrence, showed intake of 250 mg of 10-percent forskolin extract twice daily for a 12-week period favorably altered body composition while concurrently increasing bone mass and serum free testosterone levels in overweight and obese men.⁹³

Traditionally ingested to improve stamina and to facilitate rapid recovery from injuries, ginseng is another botanical used widely by athletes for its possible adaptogenic effects on cardiovascular, central nervous, endocrine and immune systems, and metabolism.⁹⁴ Rat studies from the University of Leon in Spain found ginseng extract protected muscle from exercise-induced oxidative stress,⁹⁵ inflammation and injuries caused by eccentric contraction during exercise by reducing plasma creatine kinase levels, lowering lipid peroxidation (as measured by malondialdehyde levels) by approximately 15 percent, and reducing markers of inflammation (beta-glucuronidase and glucose-6-phosphate dehydrogenase [G6PDH] levels).⁹⁶ And Taiwanese studies have shown ginseng inhibits leakage of creatine kinase, a sign of oxidative stress, potentially decreasing skeletal muscle cell membrane damage.⁹⁷ Ginseng may also increase endurance; a California State Polytechnic University (Pomona, Calif.) study showed ginseng supplementation of 1,350/d for 30 days in young adults improved endurance time to exhaustion, and lowered mean blood pressure and improved oxygen uptake during endurance exercise.⁹⁸ In addition, ginseng may improve psychomotor performance in strategic sports; a randomized, double blind, placebo-controlled Polish study on young soccer players showed administration of 350 mg/d of ginseng for six weeks shortened reaction time at rest and during exercise, shifting the exercise load associated with the shortest reaction time toward higher exercise loads.⁹⁹

The herb guarana, derived from an evergreen vine indigenous to the Amazon basin, is another popular stimulant within the realm of sports nutrition. Similar to caffeine in effect, guarana is known to stimulate the nervous system and increase metabolism.¹⁰⁵ Brazilian researchers examined the effect of 14 days of guarana supplementation (using a decaffeinated extract, to isolate the effects of caffeine from other components of guarana) upon aspects of lipid metabolism in trained rats and sedentary controls.¹⁰⁶ Body weight, food and water intake, body composition and plasma levels of exercise-related toxins were assessed. Rats given decaffeinated guarana had lower levels of the toxin oleate; trained animals given the whole extract (containing caffeine) had lower serum concentrates of lactate. Whole guarana extract produced higher muscle glycogen content in both trained and untrained rats. The researchers concluded the results show a beneficial effect of guarana on aspects of lipid metabolism, an effect abolished by decaffeination. Guarana may also suppress exercise-induced hypoglycemia. A Japanese study showed water extract of guarana (500 mg/kg) increased blood glucose levels, decreased liver glycogen content and significantly suppressed exercise-induced hypoglycemia in mice within 60 minutes of oral maltose administration.¹⁰⁷

Bitter orange, or Citrus aurantium (CA), is an herb used by athletes for its thermogenic properties. In a study conducted by researchers from the McGill Nutrition and Food Science Center at the Royal Victoria Hospital in Montreal, Canada, supplementation with CA (as Advantra Z®, from Nutratech) led to an increased thermogenic response and a measurable increase in metabolic rate in lean men and women when consumed alone and in conjunction with nutrition bars.¹⁰⁸ Another clinical trial demonstrating the ability of CA to increase metabolic rate without affecting blood pressure, held at Royal Victoria Hospital in Montreal, used indirect calorimetry to assess whether CA increased metabolic rate.¹⁰⁹ Thermic response to Advantra Z was higher in men when taken without food, and higher in women when taken with a meal, possibly due to diminished sympathetic nervous system response to meals in females. The researchers also found CA had no effect on blood pressure.

Believed to increase strength and performance, supplemental creatine is converted within the body to phosphocreatine (PCr), an energy source particularly useful for activities requiring high-intensity bursts of energy, such as sprinting and weightlifting. A clinical trial out of the University of Technology in Sydney, Australia, randomized 18 males to receive 20 g/d of creatine for seven days followed by l0 g/d of creatine for a further 21 days (n=9), or a placebo for the same period.¹¹³ Test subjects completed aerobic testing on a cycle ergometer before and after supplementation. The creatine group showed a significant increase in body mass, decrease in maximum heart rate and decrease in submaximal VO2 (oxygen uptake); other oxygen consumption measures and exercise time to exhaustion in this group showed decreasing trends that approached significance. The researchers concluded creatine ingestion improves submaximal cycling efficiency, likely due to peripheral factors such an increase in muscle PCr, rather than central changes.

Creatine may be most applicable in resistance training programs, due to the compound’s purported ability to increase muscle mass and strength. A six-week controlled clinical trial from the University of Saskatchewan, Canada, conducted on six males and five females supplemented with creatine or placebo and subjected to resistance training of limbs two times per week found supplementation with creatine after training of the arms resulted in greater increases in muscle thickness of the arms, particularly in males.¹¹⁴ Similarly, a Belgian study investigating the effects of oral creatine supplementation on muscle PCr concentration, muscle strength and body composition in 19 young female volunteers during 10 weeks of resistance training found long-term creatine supplementation enhanced the progress of muscle strength during resistance training in sedentary females.¹¹⁵

Magnesium and creatine have been combined in formulation to enhance their synergistic support of production of energy-providing ATP within the body. According to a clinical trial at Western Washington University, Bellingham, magnesium-creatine chelate (as Creatine MagnaPower™, from Albion Advanced Nutrition) may help runners delay exhaustion compared to placebo, through effects on accumulated oxygen deficit.¹¹⁶ In addition, supplementation of animals with magnesium-creatine chelate (as Creatine MagnaPower) more effectively enhanced ability to generate and regenerate ATP for muscular performance, in comparison to supplementation with creatine monohydrate, creatine monohydrate plus magnesium oxide, creatine monohydrate plus magnesium amino acid chelate, or placebo.¹¹⁷

The steroid hormone DHEA (dehydroepiandrosterone), known as the “mother hormone” due to its ability to convert to other hormones, including estrogen and testosterone, within the body, encourages weight loss in individuals following an exercise program.¹¹⁸ Although DHEA supplements are popular among athletes, they may produce negative androgenic and estrogenic side effects within the body. Instead, 3-acetyl-7-oxo-dehydroepiandrosterone (7-oxo-DHEA), a DHEA metabolite, may deliver the benefits of DHEA without affecting endogenous hormone levels. In a double-blind, placebo-controlled study, 30 adults (28 women and 2 men between 33 and 56 years of age) with an average mean body mass index (BMI) of 31.9 were administered 100 mg of 7-oxo-DHEA (as 7-Keto™, from Humanetics Corp.) twice daily (Group 1) or placebo (Group 2) for eight weeks.¹¹⁹ All subjects participated in a supervised exercise training program with aerobic and anaerobic components three times per week and were instructed to follow a diet of approximately 1,800 kcal/d outlined by a registered dietitian. Group 1 lost a significant amount of body weight (2.88 kg) and body fat (1.8 percent) compared with Group 2 (0.97 kg and 0.57 percent, respectively) over the test period. In addition, Group 1 experienced no significant changes in testosterone and estradiol levels throughout the study.

Another supplement popular among athletes is phosphatidylserine (PS), a phospholipid involved in the production of cellular membranes throughout the body. In a study conducted at St. Cloud State University, Minnesota, supplementation with PS lowered levels of creatine kinase, a marker of oxidative damage, 24 hours after exercise in 12 trained runners administered 300 mg/d, 600 mg/d or placebo for 15 days, followed by a 90-minute run on the final day.¹²⁴ However, a study out of the University of Wales, Swansea, on male soccer players given PS or placebo found PS did not reduce markers of muscle damage and lipid peroxidation following exhaustive running, nor cortisol response nor perceived soreness, although PS supplementation tended to increase running time to exhaustion.¹²⁵ The researchers called for future research to investigate potential ergogenic properties of PS.

The double blind, placebo-controlled study randomized 180 men and women, aged 18 to 65, with a BMI of 25 kg/m2 to 30 kg/m2, to receive 4.5 g/d of CLA-free fatty acid, 4.5 g/d of CLA-triglycerides (as Tonalin®, from Cognis Nutrition & Health), or a placebo of 4.5 g/d olive oil. Scientists regularly assessed each subject’s body weight, BMI, body composition and blood samples. A significant decrease in BFM was observed in both groups receiving CLA compared to placebo, and the CLA-free fatty acid group had an increase in LBM compared to placebo. The authors of the study noted the results were not associated with changes in diet or exercise, and concluded both forms of CLA caused a significant decrease of body fat mass over a oneyear period in healthy, overweight adults.

Another study on CLA and body composition investigated the effects of six months of supplementation with 7 g/d CLA (as Clarinol™, from Lipid Nutrition) in seven novice and seven advanced male and female resistance-trained athletes.¹³⁰ Test subjects performed a standardized training routine three times per week and were assessed for BMI, body composition and nutrient intake. In spite of a higher energy intake, a significant reduction of body fat and an increase in body cell mass was observed in both groups. The effects recorded in the experienced group were not greater than those observed in the group of beginners.

Nutrition is a common denominator in the athletic world, affecting performance and results among serious athletes and weekend warriors alike. Supplementation with various vitamins, minerals, botanicals and other compounds is an important, integral part of any training program, fueling, repairing and protecting physically active individuals as they pursue their fitness goals.

Share this article: Email, Slashdot, Digg, Del.icio.us, Yahoo!MyWeb, Windows Live Favorites, Furl
Add this article feed to: RSS, My Yahoo, Newsgator, Bloglines