Contrasting plasma free amino acid patterns in elite athletes: association with fatigue and infection.

Abstract

Aim-There is little information on the plasma free amino acid patterns of elite athletes against which fatigue and nutrition can be considered. Therefore the aim was to include analysis of this pattern in the medical screening of elite athletes during both especially intense and light training periods. Methods-Plasma amino acid analysis was undertaken in three situations. (1) A medical screening service was oVered to elite athletes during an intense training period before the 1992 Olympics. Screening included a blood haematological/ biochemical profile and a microbial screen in athletes who presented with infection. The athletes were divided into three groups who diVered in training fatigue and were considered separately. Group A (21 track and field athletes) had no lasting fatigue; group B (12 judo competitors) reported heavy fatigue at night but recovered overnight to continue training; group C (18 track and field athletes, one rower) had chronic fatigue and had been unable to train normally for at least several weeks. (2) Athletes from each group were further screened during a post-Olympic light training period. (3) Athletes who still had low amino acid levels during the light training period were reanalysed after three weeks of additional protein intake. Results-(1) The pre-Olympics amino acid patterns were as follows. Group A had a normal amino acid pattern (glutamine 554 (25.2) µmol/l, histidine 79 (6.1) µmol/l, total amino acids 2839 (92.1) µmol/l); all results are means (SEM). By comparison, both groups B and C had decreased plasma glutamine (average 33%; p<0.001) with, especially in group B, decreased histidine, glucogenic, ketogenic, and branched chain amino acids (p<0.05 to p<0.001). None in group A, one in group B, but ten athletes in group C presented with infection: all 11 athletes had plasma glutamine levels of less than 450 µmol/l. No intergroup diVerences in haematological or other blood biochemical parameters, apart from a lower plasma creatine kinase activity in group C than in group B (p<0.05) and a low neutrophil to lymphocyte ratio in the athletes with viral infections (1.2 (0.17)), were found.(2) During post-Olympic light training, group A showed no significant amino acid changes. In contrast, group B recovered normal amino acid levels (glutamine 528 (41.4) µmol/l, histidine 76 (5.3) µmol/l, and total amino acids 2772 (165) µmol/l) (p<0.05 to p<0.001) to give a pattern comparable with that of group A, whereas, in group C, valine and threonine had increased (p<0.05), but glutamine (441 (24.5) µmol/l) and histidine (58 (5.3) µmol/l) remained low. Thus none in group A, two in group B, but ten (53%) in group C still had plasma glutamine levels below 450 µmol/l, including eight of the 11 athletes who had presented with infection.(3) With the additional protein intake, virtually all persisting low glutamine levels increased to above 500 µmol/l. Plasma glutamine rose to 592 (35.1) µmol/l and histidine to 86 (6.0) µmol/l. Total amino acids increased to 2761 (128) µmol/l (p<0.05 to p<0.001)...

Immune responses to intensified training and overtraining

“…low scores for vigour; increased scores for fatigue and depression) • Chronic fatigue; general malaise/flu-like symptoms • Sleep disturbance • Increased early morning or sleeping heart rate • Loss of appetite • Gastrointestinal disturbance • Recurrent infection • Slow wound healing Anecodotal reports from athletes and coaches of an increased infection rate with UPS have also been supported by several empirical studies. In a cohort study of highly trained athletes prior to the Olympic Games, over 50% of the athletes who reported symptoms of UPS presented with infection compared with none of the athletes in the over-reached group (Kingsbury et al 1998). It appears, therefore, that suppression of immune system function as a consequence of excessive physical and/or psychological stress can clinically manifest as an increased susceptibility to infectious illness.…”

“…Glutamine is an amino acid essential for the optimal functioning of lymphocytes, and in vitro studies have demonstrated that in the absence of glutamine lymphocytes are unable to proliferate. Because many athletes with UPS, and those undergoing intense exercising training, present with low plasma glutamine concentrations , Kingsbury et al 1998, Rowbottom et al 1995, it is hypothesized that the fall in plasma glutamine levels cause lymphocyte function to become depressed, thus rendering the athlete more susceptible to infections. However, a weakness in this theory concerns the in vitro studies.…”

Modification of immune responses to exercise by carbohydrate, glutamine and anti-oxidant supplements

“…Interestingly, there is some evidence that an additional intake of 20-30 g protein/day can restore depressed plasma glutamine levels in overtrained athletes. 45 Several scientists have suggested that exogenous provision of glutamine supplements may be beneficial by preventing the impairment of immune function following prolonged exercise. Castell et al have provided the only prophylactic evidence that an oral glutamine supplement (5 g in 330 mL water) consumed immediately after and 2 h after a marathon reduces the incidence of URTI in the 7 days following the race.…”

Overview of the epidemiology of exercise immunology

“…41,[46][47][48] Of eight studies with intermediate ratings (8-13 points), five have noted an increased susceptibility to infection; four of these involved distance runners 32,36,40,43,49 and one a mixed sample of international competitors where 19 of 39 athletes had developed signs of chronic fatigue. 50 Of the three studies with a decrease in susceptibility to upper respiratory infection, one involved moderate exercise in elderly subjects 38 and two involved distance runners, 51 one being a group who were covering training distances of up to 42 km/week. 37 In the 10 studies with the lowest ratings, five have shown an increase of infections with increased exercise; these included international-level swimmers, 52 orienteers, 29 university athletes, 35 recreational swimmers 44 and participants in a rigorous special warfare training program.…”

“…A period of heavy training may also induce deficiencies of key nutrients such as glutamine, arginine, L-carnitine, essential fatty acids, vitamin B6, vitamin C, vitamin E, folic acid and trace elements. The impact on well-trained competitors remains controversial, 59 but deficiencies in a number of these substances could have adverse effects on the immune response 50,[59][60][61][62][63] and thus on susceptibility to infection.…”