Nutritional Needs According to the Demands of Your Sport (Part 2)
Current research suggests that athletes need a more detailed approach at nutrition to reflect the metabolic and physiologic demands of their training or competition.
A. Nutrient Strategies for Athletes using the ATP-PC System:
Athletes engaged in sports that require ballistic muscular contractions with maximal force production have unique amino acid requirements. In a recent study, competitive sprinters and jumpers completed two sets of two testing sessions, interspersed with a five-week training period, while the researchers measured the effects of the activity on a number of blood variables. During the five week macrocycle, the athletes completed a periodized off-season program, and consumed a diet which consisted of 53% carbohydrates, 32% fat, and 15% protein (1.25g protein per kg of body weight).
After the 5 week training session, blood tests revealed that fasting levels of amino acids had dropped 20%, while testosterone levels increased by 25%. This data suggests that power training had robbed the body of its amino acids stores, presumably as the body accounted for exercise-induced musclar damage. The testosterone increases indicate that the body was tending towards a healthy anabolic state, but was amino acid poor. The implication here is that with greater amino acid consumption (1.7g/kg), a higher rate of protein sysnthesis would result. (Komi P, et al. Journal of Strength and Conditioning Research, 2002).
B. Nutrient Strategies for Athletes using the Lactic Acid System:
Athletes competing in sports which require a mixture of power, high output bursts, and mid-range endrance activities will benefit from higher protein intake, as well as a specialized approach to fluids and antioxidants. A 1992 Journal of Applied Physiology study conducted by Tarnopolsky et al, compared a group of experienced strength-trained athletes with a group of sedentary controls. Both groups were tested at three protein intake levels – low, moderate and high (0.86, 1.4 and 2.4 g/kg body weight respectively). The results indicated that the protein intake required to maintain body protein levels was 1.4g/kg for strength athletes and 0.69g/kg for sedentary subjects. Increasing protein intake from low to moderate enhanced the rate of protein synthesis in strength athletes, but increasing to the high level did not yield further benefits.(Tarnopolsky, Journal of Applied Physiology, 1992).
In addition to the increased protein strategy, lactic acid system athletes can benefit from adding antioxidants such as Vitamin C (500mg) and Vitamin E (400IU) during the post workout phase (<1 hour post workout). During the acute post workout phase, these antioxidants help to diminish free-radical induced cellular damage. Fluid and electrolyte replenishment, including upwards of 2L of water in the first hour of the post-workout phase is also prescribed by many exercise physiologists.
C. Nutrient Strategies for Athletes using the Aerobic Energy System:
Recent studies have demonstrated the importance of both glycogen and amino acid replenishment for enhancing recovery with endurance athletes. Scientists in Maastritch University in the Netherlands examined the effects of (a) carbohydrates-only drink (1.2 g/kg per hour of 60:40% maltodextrin/glucose) and the carbohydrates drink plus (b) zero, (c) 0.2, or (d) 0.4 g/kg per hour of a protein hydrolysate and amino acid mixture on insulin responses.
Eight male cyclists ingested these beverages every 30 minutes for 3 hours after a long bike ride. Only the beverages containing the carbohydrates and protein produced significant insulin responses (+52% and +107% for the 0.2 and 0.4 g/kg per hour drinks, respectively). (Van Loon, LJ, et al, American Journal of Clinical Nutrition, 2000).
Elevated insulin concentrations enhance glycogen synthase activity, which in turn promotes glycogen synthesis. The addition of protein hydrolysate and amino acids doubled glycogen synthesis rates even more, a vital process for the endurance athlete.