Nutrients for a Stronger Athletic Body

For shedding those unwanted pounds in order to get back into fighting shape, bitter orange extract (Citrus aurantium; CA) is popular. It has been purported to stimulate thermogenesis, reduce weight, increase the percentage of lean muscle in relation to total body mass, improve athletic performance and help suppress appetite. A recent study examined the effects of bitter orange extracts (as Advantra Z® , from Nutratech Inc.).²⁵ The three-arm, double blind, placebo-controlled, crossover study found exercise tolerance improved 83 percent of the time following use of a performance-enhancing dietary supplement containing Advantra Z. The study also said there was no increase in post-exercise heart rate, systolic blood pressure or temperature, and no differences in exercise-related oxygen consumption, serum lactate or insulin. A similar study from McGill Nutrition and Food Science Center at the Royal Victoria Hospital in Montreal, Canada demonstrated supplementation with Advantra Z 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.²⁶ A clinical trial from the same group of researchers compared the thermic response to a meal between men and women of varied body composition and to determined whether adrenergic amines extracted from CA induced an increase in metabolic rate and enhanced the thermic response to the meal.²⁷ In 30 healthy, weight-stable subjects (17 women, 13 men; BMI: 20 to 42 kg/m²), body composition was determined and the thermic effect of food (TEF) of a 1.7-MJ, 30-g protein meal was determined intermittently for 300 minutes by indirect calorimetry. In a subset of 22 subjects, TEF was significantly lower in women than men, independently of age and magnitude of adiposity. The thermic response to CA alone was higher in men, but, when added to the meal, CA increased TEF only in women and to values no longer different from men. CA had no effect on blood pressure and pulse rate but increased epinephrine excretion by 2.4-fold.

Soy and whey, two proteins used to increase lean muscle development, are at the forefront of building stronger muscles. In comparison to whey, soy improves antioxidant status,^28,29 possibly because of the naturally-occurring isoflavone content. The antioxidant components of isoflavones can diminish oxidative stress caused by exercise, which may lead to fatigue, muscle soreness, inflammation and muscle injury. Additionally, soy protein contains a high concentration of three branched-chain amino acids (BCAAs)—leucine, isoleucine and valine—plus other amino acids, glutamine and arginine, which together may have an impact on muscle building.^30,31 However, a comparison study on soy and whey proteins in recreationally trained young women found soy consumption, but not whey intake, increased pre-exercise serum antioxidant status while decreasing post exercise blood levels of peroxides and creatine kinase—toxins produced through oxidative stress.³²Researchers had recreationally trained, young adult women consume antioxidant-rich soy protein or antioxidant-poor whey protein for four weeks (40 g/d protein). A moderate intensity, weight resistance exercise session was done before and after the four-week period. The study concluded moderate intensity exercise exerted variable effects on serum lipid peroxides with decreases occurring with four weeks of soy intake, which also produced other antioxidant effects. In contrast, a recent study out of the Indiana University School of Medicine, Evansville, found soy and whey protein in the skeletal muscle of exercised rats synthesize protein at comparable measures after strenuous exercise.³³ Rats were given either carbohydrates only (C), carbohydrates and soy protein (CS), or carbohydrates and whey protein (CW)—one hour after a nearly 2.5-hour treadmill run. An hour later, the degree of muscle protein synthesis was measured in each rat and compared to control. Insulin and BCAA concentrations were higher in the CS and CW groups, with serum leucine and isoleucine the highest in the CW group. Compared with the C group, both the CS group and CW group increased protein synthesis in skeletal muscle. The study suggests both soy and whey proteins are useful sources of protein for muscle support following aerobic exercise.

Another study confirmed supplementing with either a soy or whey protein increased lean tissue mass and strength when taken during resistance training.³⁴ In the double blind study, 27 untrained healthy subjects, (18 female, 9 male) ages 18 to 35 years, were randomly assigned to take either whey protein (1.2 g/kg body mass whey protein + 0.3 g/kg body mass sucrose power), soy protein (1.2 g/kg body mass soy protein + 0.3 g/kg body mass sucrose powder) or a placebo for six weeks.

Whether training for an Olympic triathlon or simply jogging around the block, total body health is extremely important. Proper supplementation and care will guarantee a body that is faster, stronger, better.

References available on the next page.