Increases in Circulating Cell-Free DNA During Aerobic Running Depend on Intensity and Duration.
OBJECTIVE
Increases in concentrations of circulating cell-free DNA (cfDNA) have recently been demonstrated to occur in a variety of exhausting and vigorous exercise settings. Here, the authors assessed the association of cfDNA with exercise duration and intensity in a controlled test-retest setting of a regenerative up-to-moderate-level aerobic run.


METHODS
In a pretest, the lactate threshold (LT) was determined in 13 participants (range 10.8-13.4 km/h) by using a step-wise incremental running test. The speed of the 2 endurance runs was set to 9.6 km/h for 40 min; for the participants with an LT below the median (12.8 km/h; G1), this was a moderate aerobic run, and for those with an LT above the median, this was a regenerative run (G2). Capillary cfDNA, lactate, and rating of perceived exertion (RPE) were assessed before, every 10 min during, and after the runs.


RESULTS
During the last 30 min of the 2 runs, lactate did not increase, whereas cfDNA increased steadily (3.46-fold for G1 and 2.05-fold for G2). Intraclass correlation for cfDNA was high (r = .81, P < .0001) for all runners but higher for male participants (r = .92, P < .0001). The correlations of cfDNA and lactate with RPEs were r = .58 (P < .0001) and r = .32 (P < .05), respectively.


CONCLUSIONS
Both duration and level of intensity were significantly associated with accumulation of cfDNA. The correlation with RPE and the high test-retest reliability suggest that cfDNA might be applicable as a marker to monitor individual training load for aerobic and intermittent exercises. Future randomized, controlled, longitudinal training studies will have to reveal the full potential of cfDNA as an exercise-physiology marker.
Nils
N
Haller
Suzan
S
Tug
Sarah
S
Breitbach
Arne
A
Jörgensen
Perikles
P
Simon
D000328:Adult; D000073888:Cell-Free Nucleic Acids / Q000097:blood*; D005080:Exercise Test; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D015203:Reproducibility of Results; D012420:Running / Q000502:physiology*; D055815:Young Adult
D000073888:Cell-Free Nucleic Acids; D019344:Lactic Acid
aerobic exercise; exercise-physiological marker; plasma DNA