Tamelevicius, N., Sparks, M., Moss, S. J., de Boer, M. R., & Campbell, J. (2014). Blood lactate dynamics and heart rate variability during ultra-distance relay running. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 1310.

This study analyzed blood lactate levels and monitored heart-rate variability in male runners (N = 6) before, during and after an ultra-long distance relay run. Ss were monitored during the 317 km relay run. Ss were rotated and each completed six legs during the race. Average distance of a race leg was ~8.8 km. Capillary blood samples were taken and blood lactate analyzed pre-, post-, and 1, 3, 5, 10, and 15 minutes into recovery. Heart-rate variability was monitored with Actiheart 24 hours before, during, and 24 hours after the race. Heart-rate variability was evaluated using root mean square of successive differences.

Blood lactate levels immediately after each race leg were (~3.08 mmol/L), significantly higher than before (~2.23 mmol/L) each leg of the race. Within 15 minutes of leg completion, blood lactate cleared. Blood lactate levels decreased as race legs progressed. Heart-rate variability pre-race was higher than post-race. Heart rate variability did not decline from stage 1 to 6, although it declined from pre-stage to post-stage recovery.

Implication. Blood lactate increases during ultra-distance running relay-race legs but decreases as race legs progress. The load experienced from the ultra-distance relay run does not substantially effect heart-rate variability during the race but may suggest accumulated fatigue when comparing pre- and post-race day values.

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