Performance and cardiac evaluation before and after a 3-week training camp for 400-meter sprinters - An observational, non-randomized study.

Objective: To study the performance and cardiovascular function after a 3-week training camp in athletes competing in an anaerobically dominant sport.
Methods: Twenty-three competitive 400-m athletes were enrolled in this non-randomized study, 17 took part in a 3-week training camp in South-Africa (intervention), but one declined follow-up assessment, while 6 pursued in-door winter training in Sweden and served as controls. Electrocardiography, transthoracic echocardiography, blood test analyses, maximal exercise tolerance test, and a 300-m sprint test with lactate measurements ([La]peak) were performed before and after the training camp period.
Results: At baseline, there were no clinically significant pathological findings in any measurements. The training period resulted in improved 300m-sprint performance [n = 16; running time 36.71 (1.39) vs. 35.98 (1.13) s; p<0.01] and higher peak lactate values. Despite 48% more training sessions than performed on home ground (n = 6), myocardial biomarkers decreased significantly (NT-pro BNP -38%; p<0.05, troponin T -16%; p<0.05). Furthermore, resting heart rate (-7%; p<0.01) and left ventricular systolic and diastolic volumes decreased -6% (p<0.01) and -10% (p<0.05), respectively.
Conclusions: Intense physical activity at training camp improved the performance level, likely due to improved anaerobic capacity indicated by higher [La]peak. There were no clinically significant adverse cardiac changes after this period of predominantly anaerobic training.
Competing Interests: CMM is the co-founder of Stockholm Exercise Analytics and Silicon Valley Exercise Analytics. This does not alter our adherence to PLOS ONE policies on sharing data and materials. These sponsors had no role in the study design, in the collection, analysis and interpretation of data, in the writing of the report; or in the decision to submit the article for publication.