Sperlich, B., Achtzehn, S., de Marees, M., & Mester, J. (2009). Creatine kinase monitoring and performance during three weeks of high altitude training in elite middle and long distance runners. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

"Creatine kinase (CK) is a highly sensitive marker for muscle damage. It is well known that a wide range of exercise modalities such as high-intensity, volume training, and especially weight-bearing eccentric exercise cause the greatest rises in CK. Usually, peak values are seen 24-48 hours after such exercise. Therefore, a daily monitoring of CK and other exercise relevant strain markers could facilitate coaches in controlling training loads. Middle and long distance runners perform training camps in order to increase performance. Within these, training volume and/or intensity increase considerably compared to "normal" training procedures. Until today, no clear consensus exists on which threshold of CK elevation correlates with changes in performance as well as other monitoring parameters."

Highly-trained middle and long distance runners (M = 7; F = 2) from the German National Track and Field team were monitored daily during a training camp at 2,100 m altitude. Values for creatine kinase, resting heart rate, and body weight were collected between 7 and 9 AM. Additionally, Ss had to rate their overall body perception and sleep quality on a six point scale (1 = very good, 6 = very poor). Running speed at 3 mmol/l blood lactate was assessed before and after the training camp. All middle and long distance runners performed the same number of training sessions. Each athlete performed two to three training sessions per day. One day with less training volume and intensity was programmed after 3-5 consecutive days depending on training advancement. Training intensity was controlled by heart rate and lactate values, as well as creatine kinase and perceptual values. One to two days of degraded body perception and sleep quality accompanied by elevated creatine kinase values resulted in a reduction of intensity or training volume.

Running speed at 3 mmol/l blood lactate increased from ~4.4 before the camp to ~4.6 after. Baseline values for creatine kinase were quite varied among Ss. The highest creatine kinase values during the three weeks were found on day 17 of 20, and again were particularly varied. The mean creatine kinase values for Ss over the three weeks was elevated over baseline but with striking inter-subject variation. The individual creatine kinase kinetics over the complete period revealed individuals with generally lower values (223 U/L) and individuals with considerably higher values (501 U/L) but with the same work load. Despite clear mean increases in creatine kinase, body weight remained unchanged from pre- to post-camp. Mean sleep quality decreased by 0.5 points towards the end of the camp. Mean body perception remained unaltered.

Implication. Creatine kinase kinetics are particularly variable, even in an homogenous group of elite runners. Increases in mean creatine kinase values over the camp's three weeks did not affect performance negatively. In several cases, elevated creatine kinase kinetics correlated with degraded body perception and sleep quality. The use of measures of creatine kinase should be on an individual basis and in many cases should be expected to yield little information of value with regard to current or future performances. Using creatine kinase values to program an athlete's training appears to be a futile procedure.

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