Randomized experimental trial in a repeated measure design.
Male (n = 22) and female subjects (n = 20) completed a marathon either with a run/walk strategy or running only. Immediately after crossing the finishing line cardiac biomarkers were assessed in blood taken from the cubital vein. Before (−7 days) and after the marathon (+4 days) subjects also completed an incremental treadmill test.
Despite different pacing strategies, run/walk strategy and running only finished the marathon with similar times (04:14:25 ± 00:19:51 vs 04:07:40 ± 00:27:15 [hh:mm:ss]; p = 0.377). In both groups, prolonged exercise led to increased B-type natriuretic peptide, creatine kinase MB isoenzyme and myoglobin levels (p < 0.001), which returned to baseline 4 days after the marathon. Elevated cTnI concentrations were observable in only two subjects. B-type natriuretic peptide (r = −0.363; p = 0.041) and myoglobin levels (r = −0.456; p = 0.009) were inversely correlated with the velocity at the individual anaerobic threshold. Run/walk strategy compared to running only reported less muscle pain and fatigue (p = 0.006) after the running event.
In conclusion, the increase in cardiac biomarkers is a reversible, physiological response to strenuous exercise, indicating temporary stress on the myocyte and skeletal muscle. Although a combined run/walk strategy does not reduce the load on the cardiovascular system, it allows non-elite runners to achieve similar finish times with less (muscle) discomfort.