Perfect sport nutrition

Requirements of macronutrients depending on the type of loading

Basically, the art of perfect nutrition is to find the right balance between demand and supply. Depending on the type of physical activity, there is a great difference in required quantities and in composition of food.

A low physical activity (e.g. office work), causes a low energy demand and a normal composition of macronutrients (see figure). With increasing activity, nutrition should be adapted to the type of loading. High intensive activities accompanied by high intramuscular tension (resistance training) are causing a different profile of demand, than high volume workouts at lower intensities (endurance training).

One of the main reasons for this difference is due to an increased demand of protein after training session with high intramuscular tension. For resistance training, protein is needed for tissue repair and hypertrophy of the trained musculature (1). Taking into account that the normal diet within western industrial societies is rich in proteins, and 2/3 of the ingested amount is excreted unused, a supplementation might only make sense at very high training intensities. Bodybuilding might cause demands up to 1.6 – 1.7g/kg bodyweight (2). Phillips et al., who performed a re-analysis of nitrogen balance measurement data, even suggest a lower daily protein intake of 1.33g/kg for resistance training athletes (3).

In endurance training, protein is of minor interest, as structural changes occur to smaller extend, compared to resistance training. In contrast, the daily diet should consist to a greater proportion of carbohydrates, enabling a sufficient energy supply, especially during short- and middle distances. Nonetheless, aerobic endurance training can also increase protein need, although reasons might differ essentially from resistance training (1), as endurance training places higher demand on protein as an auxiliary fuel (2).

The more physical activity fall in the range of long term endurance performance, fat is playing a central role in energy supply. With decreasing exercise intensities there is a shift from carbohydrate to fat as the main source of energy (1). This is supported by some studies that found enhanced performance and longer distance to exhaustion following a high-fat diet (4;5).

Further, a “nutrition-periodization”, i.e. a high-fat diet followed by a high-carbohydrate intake, is sometimes recommended for endurance athletes, to increase endogenous glycogen stores. However, a literature review of Burke and Hawley found that “despite marked changes in the patterns of fuel utilization that favor fat oxidation, fat-adaptation/CHO restoration strategies do not provide clear benefits to the performance of prolonged endurance exercise” (6)



Reference List

(1) Reimers K. Nutritional Factors in Health and Performance. In: Baechle TR, Earle RW, editors. Essentials of Strength Training and Contioning. 3 ed. Champaign: Human Kinetics; 2008. 202-233.
(2) Wilmore JH, Costill DL, Gleim GW. Physiology of Sport and Exercise. Medicine & Science in Sports & Exercise 1995; 27(5).
(3) Wackerhage H, Atherton P. Adaptation to resistance training. In: Spurway N, Wackerhage H, editors. Genetics and Molecular Biology of Muscle Adaptation. 1 ed. Churchill Livingstone: Elsevier; 2006. 197-225.
(4) Rowlands DS, Hopkins WG. Effects of high-fat and high-carbohydrate diets on metabolism and performance in cycling. Metabolism 2002; 51(6):678-690.
(5) Muoio DM, Leddy JJ, Horvath PJ, Awad AB, Pendergast DR. Effect of dietary fat on metabolic adjustments to maximal VO2 and endurance in runners. Med Sci Sports Exerc 1994; 26(1):81-88.
(6) Burke LM, Hawley JA. Effects of short-term fat adaptation on metabolism and performance of prolonged exercise. Med Sci Sports Exerc 2002; 34(9):1492-1498.