2.8. Creatine Kinase
Plasma CK collected pre and immediately post exercise and 24, 48 and 72 h post exercise was measured at a commercial laboratory (Canterbury Health Laboratories, Christchurch, New Zealand). The analysis of CK was quantified by spectrophotometry, which measured the rate of nicotinamide adenine dinucleotide (NADH) formation from an enzymatic reaction using an automated Beckman Coulter AU5822 analyser. Plasma, and not serum, was the preferred analyte by the laboratory, and the reference intervals for plasma CK in males were reported to be between 60 and 22 U/L.