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PURPOSE: We observed in previous studies that incremental running tests to exhaustion and continuous aerobe running leads to significant increases of cell-free DNA (cfDNA) in capillary blood, which showed a high positive correlation with total energy expenditure. Here we investigated the increases of cfDNA during different interval loads with a focus on metabolic rates, heart rate (HR), and TRIMP. We hypothesized that cfDNA shows a high association with carbohydrate energy expenditure. MET...PURPOSE: We observed in previous studies that incremental running tests to exhaustion and continuous aerobe running leads to significant increases of cell-free DNA (cfDNA) in capillary blood, which showed a high positive correlation with total energy expenditure. Here we investigated the increases of cfDNA during different interval loads with a focus on metabolic rates, heart rate (HR), and TRIMP. We hypothesized that cfDNA shows a high association with carbohydrate energy expenditure. METHODS: 14 male subjects were subjected to a stepwise incremental exercise test until exhaustion to determine the individual anaerobic threshold (IAT; as LT + 1.5 mmol/l) and subsequently participated in three different interval training sessions. cfDNA and lactate were taken after every step and metabolic data were monitored continuously after a 10min warmup phase on the treadmill (+1.5%) during 6 x 400m intervals at 18km/h with 2min pauses, 6 x 400m intervals at 18km/h with 5min pauses, and 6 x 1000m intervals at IAT with 2min pauses. The order of the first two tests that only differed in duration of pause was randomized. Heart rate and subsequent calculation of TRIMP was done based on ECG Monitoring. RESULTS: cfDNA analysis showed a significantly higher increase in the 400m interval setting with short pause time (8.2-fold; 95% CI: 6.3-10.6; p<0.0001) compared to 400m interval setting with long pause time (3.4-fold; 95% CI: 2.6-4.4; p<0.0001). In contrast to cfDNA TRIMP showed a significantly higher increase in the 400m interval setting with a long pause time (long: 4.8-fold; 95% CI: 4.4-5.2; p<0.0001) compared to 400m interval setting with short pause time (4.3-fold; 95% CI: 4.0-4.7; p<0.0001). In a global analysis across all interval tests and points in time cfDNA increased 7.0-fold (95% CI: 5.4-9.1; p<0.0001) and the highest correlation of this increase with all other physiological parameters was with carbohydrate energy expenditure (r= 0.87; p<0.0001). CONCLUSIONS: cfDNA appeared to reflect training load of the 400m interval settings more properly than TRIMP. Here we report for the first time a high correlation between cfDNA and carbohydrate energy expenditure. Further studies will have to investigate the validity of cfDNA releases during exercise as a marker for carbohydrate energy expenditure.» weiterlesen» einklappen

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Sport