Differences in muscle pain and plasma creatine kinase activity after ‘up’ and ‘down’ Comrades marathons

Abstract

Objective. The aim of this study was to compare the acute changes in muscle pain and plasma creatine kinase (CK) activity following the ‘up’ and ‘down’ Comrades marathon. Design. This was a quasi-experimental design. Eleven male runners (39.7±9.3 years) completed the ‘up’ Comrades marathon, and 11 male runners (41.0±8.4 years) completed the ‘down’ Comrades marathon the following year. Maximum oxygen consumption and peak treadmill running speed were measured 2 weeks before the race. Daily measurements of muscle pain and plasma creatine kinase (CK) activity were recorded 1 day before, and for 7 days after the race. Results. Muscle pain remained significantly elevated for up to 7 days after the Comrades marathon, compared with pre-race values (p<0.0009). The pain scores following the ‘down’ run were significantly higher than the pain scores following the ‘up’ run for at least 7 days after the race (p<0.004). Plasma CK activity remained significantly elevated for up to 5 days after the Comrades marathon, compared with pre-race values (p<0.007). Plasma CK activity following the ‘down’ run was significantly higher than the plasma CK activity following the ‘up’ run for 5 days after the race (p<0.04). A high degree of intra-individual variability in plasma CK activity was observed. Conclusions. The ‘down’ Comrades marathon causes significantly more muscle pain and plasma CK activity compared with the ‘up’ Comrades marathon. Further studies are required to accurately define the regeneration of muscle following the Comrades marathon.