The effect of arginine or glycine supplementation on gastrointestinal function, muscle injury, serum amino acid concentrations and performance duringa marathon run

Gastrointestinal bleeding and increased intestinal permeability have been o bserved in marathon runners. We sought to determine if L-arginine would be useful for prevention of these complications. Twenty-three runners were ran domized to receive L-arginine (A) or glycine (placebo) (G), 10 grams 3 time s daily for 14 days prior to the 1997 Houston-Methodist Marathon. Serum, st ool hemoccults and lactulose:mannitol permeabilities were obtained at basel ine, immediately after completion of the marathon and approximately 48 hour s later. Runners rated their symptoms of nausea and vomiting, belching and indigestion, abdominal pain and bloating, diarrhea, and extremity pain on a 1 - 5 scale of increasing severity. The L:M was unchanged in either group during the three collections. Occult bleeding occurred in 8%/20% in A and G groups, respectively, p = NS) immediately post-marathon. No runners had oc cult bleeding 48 hours post-race. Gastrointestinal symptom scores were mini mal to nonexistent. Extremity pain scores were similar for groups A and G ( 2.1 +/- 1.4 and 2.8 +/- 1.6, respectively, (p = NS). Fluid intake was simil ar between both groups (1875 +/- 1547 vs. 1506 +/- 970 ml, p = NS). Serum a mylase was normal at baseline and remained virtually unchanged. Serum lipas e was normal at baseline and immediately post-race in both groups, but incr eased at 48 hours post-race (82.2 +/- 34.3 to 121.5 +/- 53.3 mg/dl [A], p = 0.02 and 114.3 +/- 55.7 to 181.9 +/- 162.2 mg/dl [G], p = 0.09). CPK incre ased significantly and similarly in both groups immediately post-race, and even more dramatically 48 hours post-race (130.3 +/- 130.8 to 738.8 +/- 902 .9, p = 0.007 to 1966.5 +/- 3.166.0 mg/dl [A] and 140.9 +/- 77.9 to 863.0 /- 772.3, p = 0.003 to 5619 +/- 10636.8mg/dl [G]). Modest post-race decreas es were seen in most serum amino acids in both groups. Finish times were lo nger than predicted (23 +/- 21 and 9 +/- 7 min for A and G groups, respecti vely, p = 0.049). Our study failed to show a clear benefit of arginine supp lementation for the prevention of intestinal ischemia/reperfusion injury as sociated with endurance running, but either a detrimental affect on perform ance with arginine, or enhanced performance with glycine. Skeletal muscle i njury was unaffected by arginine or glycine supplementation. The delayed in crease in serum lipase suggests mild pancreatic injury, affected by either arginine or glycine supplementation.