n South African Journal of Sports Medicine - The effects of an L-methionine combination supplement on symptoms of upper respiratory tract infections and performance in ultramarathon runners before, during and after ultra-endurance exercise : original research article

Volume 16, Issue 1
  • ISSN : 1015-5163
  • E-ISSN: 2078-516X



&lt;I&gt;Objective.&lt;/I&gt; To evaluate whether supplementation with an L-methionine combination would reduce the incidence of upper respiratory tract symptoms (URTS) and improve performance in ultramarathon runners. &lt;br&gt;&lt;I&gt;Design.&lt;/I&gt; A double-blind placebo-controlled study. &lt;br&gt;&lt;I&gt;Setting.&lt;/I&gt; Twenty-one ultramarathon runners (17 males, 4 females) preparing for participation in an 87.3 km ultramarathon. &lt;br&gt;&lt;I&gt;Interventions.&lt;/I&gt; L-methionine combination supplement (L-methionine, vitamin B<sub>6</sub>, vitamin B<sub>12</sub>, folic acid and magnesium) or placebo containing potato starch. <br><I>Main outcome measures.&lt;/I&gt; Incidence of URTS was recorded during the runner's preparation for an ultramarathon race (75 days) and recovery from the same (75 days). CD4+, CD8+ cell counts and ratios were measured pre race, immediately post race and 75 days post race. VO&lt;sub&gt;2max&lt;/sub&gt; and endurance fitness (percentage VO&lt;sub&gt;2max&lt;/sub&gt; at 4 mmol&lt;sup&gt;-1&lt;/sup&gt; lactate concentration) were measured during the preparation period for the race. &lt;br&gt;&lt;I&gt;Results.&lt;/I&gt; During the preparation period the incidence of URTS was 36% in the supplement group and 80% in the placebo group (&lt;I&gt;p&lt;/I&gt; = 0.08). The incidence of URTS during the 3 weeks post race was 27% in the supplement group and 40% in the placebo group (&lt;I&gt;p&lt;/I&gt; = 0.65). The CD4+/CD8+ cell ratios were not significantly different between groups. Endurance fitness prior to the race and race times were not significantly different. &lt;br&gt;&lt;I&gt;Conclusions.&lt;/I&gt; Although the findings of the current study show that an L-methionine combination supplement did not reduce the incidence of URTS or improve performance in ultramarathon runners, benefits may be found with a more detailed investigation using larger sample sizes and immunosuppressed athletes.

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