Disturbances in BCAA Metabolism and the Effects of Feeding and Exercise in COPD

Studies on resting human muscle show that ingestion of the branched-chain amino acids (BCAA): leucine, valine and isoleucine have an anabolic effect on muscle protein metabolism. However, the effects of BCAA intake on protein metabolism during exercise are less clear. When BCAA were supplied as single amino acids, without other amino acids and/or carbohydrates, no effects were observed on protein kinetics. On the other hand, ingestion of BCAA during running appeared to reduce the catabolic effect of running on muscle protein metabolism. These experiments were all performed with mixtures of the BCAA with or without carbohydrates but not in the form of complete meals with food protein as a basis. Therefore, it is still unknown whether a protein meal, containing a substantial amount of BCAA is beneficial during exercise by inducing an anabolic effect.

Whey and Casein protein contain a substantial amount of BCAA in contrast to Soy protein. Therefore, it is hypothesized that milk-based proteins are a better and more physiological source of BCAA during exercise and will lead to more protein anabolism. Most of the available studies have been carried out in young and fit humans but there are hardly any data are available in the increasing population of the elderly. Therefore it is still unknown whether a BCAA rich protein meal can enhance the anabolic effect of exercise in older individuals.

Besides sarcopenia, a substantial part of the elderly is suffering from a chronic systemic disease such as chronic obstructive pulmonary disease (COPD). COPD represents an important health care problem. COPD is the fourth leading cause of death and will be the third leading cause worldwide in 2020. Besides the local impairment, COPD is a chronic wasting disease, associated with alterations in intermediary metabolism. Substantial disturbances have been found in BCAA (and related) metabolism in these patients at rest and during exercise. It might therefore be of clinical relevance to study the metabolic effects of BCAA rich protein meals in patients with COPD at rest and during exercise.