Changes in intramuscular amino acid levels in submaximally exercised horses - a pilot study

Abstract

The time-dependent changes in intramuscular amino acid (AA) levels caused by exercise and by feeding a protein/AA supplement were analysed in nine horses. Horses were submitted to a total of four standardized exercise tests (SETs). Amino acid concentrations were determined prior to, immediately after, 4 and 18 h after exercise. The experiment was subdivided into two consecutive periods of 3 weeks. In each period two SETs were performed. In the second period, horses were given a protein/AA supplement within 1 h after exercise. Significant changes in mean plasma AA levels similar to previous studies were noted to be time-dependent and to be associated with feeding the supplement. The intramuscular concentrations of the free AA in relation to pre-exercise levels showed significant time-dependent changes for alanine, asparagine, aspartate, citrulline, glutamine, glycine, isoleucine, leucine, methionine, serine, taurine, threonine, tyrosine and valine. Feeding the supplement significantly increased the 4 h post-exercise intramuscular concentration of alanine, isoleucine, methionine and tyrosine. At 18 h after exercise, apart from isoleucine and methionine, levels were still increased and also those of asparagine, histidine and valine in relation to none treatment. Hence, it was concluded that AA mixtures administered orally to horses within 1 h after exercise increased intramuscular AA pool.

Effects of crude protein intake from forage‐only diets on muscle amino acids and glycogen levels in horses in training

“…Part of the increase seen after intense exercise is due to plasma volume changes and total protein content has been shown to be around 20% higher after this type of exercise on both the RP and HP diets (Connysson et al 2006). Most of the increase in plasma amino acid levels is, however, due to exercise and the alterations seen on both diets agree with earlier observations on horses performing intense exercise (Miller-Graber et al 1990;Essén-Gustavsson et al 1991;Pösö et al 1991;Hackl et al 2009;van den Hoven et al 2009). Interestingly, the increase in BCAA concentration was maintained high until at least 15 min post exercise on diet HP, whereas it had started to decrease within 15 min on diet RP.…”

“…Interestingly, the increase in BCAA concentration was maintained high until at least 15 min post exercise on diet HP, whereas it had started to decrease within 15 min on diet RP. It has recently been shown that plasma and muscle leucine and isoleucine concentrations are higher post exercise when horses during 6 weeks are given a protein amino acid mixture daily within 1 h after exercise (van den Hoven et al . 2009).…”

Impacts of acute imipramine treatment on plasma and brain amino acid metabolism in mice given graded levels of dietary chicken protein

“…Accordingly, either of the two pathways and/or both pathways may have been stimulated by the increase in chicken protein levels. In fact, the present study is in accordance with a recent study in which the plasma taurine level was increased by protein supplementation (Van den Hoven et al . 2010).…”

A preliminary study on the changes in some potential markers of muscle-cell degradation in sub-maximally exercised horses supplemented with a protein and amino acid mixture

“…Recently, van den Hoven et al. (2010) showed that feeding a protein/AA supplement shortly after strenuous exercise significantly increased the 4 h post‐exercise intramuscular concentration of many AA that are supposed to be involved in protein synthesis.…”

“…Using convenience data and remains of samples gathered during the conduct of a previous study (van den Hoven et al., 2010), this explorative study aimed to gain further insight into the response patterns that are associated with inhibition of exercise‐induced proteolysis by an orally administered protein/AA mixture. In analogy with studies in man, the mRNA expression of ubiquitin in muscle biopsies was chosen as specific marker of muscle proteolysis.…”