A study compared dehydration variables, serum electrolytes, and muscle damage serum markers between runners who suffered exercise-associated muscle cramps (EAMC) and runners who did not suffer EAMC in a road marathon. Additionally, they also analyzed race pacing and training background.

The participants of the study were subjected to a cardiopulmonary exercise test. Additionally, blood and urine samples were collected and body mass (BM) was measured before and after the race. EAMC was diagnosed immediately after the race. 

The results reported-

• Development of EAMC in 24% runners during or immediately after the race.
• No difference in Body mass change, post-race urine specific gravity, and serum sodium and potassium concentrations between crampers and non-crampers.
• Runners who suffered EAMC exhibited significantly greater post-race creatine kinase and lactate dehydrogenase (LDH).
• 24 hours post-race values of both biomarkers were also higher among crampers.
• The difference in the percentage of runners who included strength conditioning in their race training approached statistical significance with EAMC: 25%, non-EAMC: 47.6%.
• The relative speed between crampers and non-crampers only differed from the 25th km onward. 

Thus it was concluded that the runners who suffered EAMC did not have a greater degree of dehydration and electrolyte depletion after the marathon but showed significantly higher concentrations of muscle damage biomarkers.

Source: J Strength Cond Res. 2020 Aug 12. doi: 10.1519/JSC.0000000000003713. Epub ahead of print. PMID: 32796418.