Abstract
The reliability of near infrared spectroscopy derived tissue oxygenation index (TOI) and total haemoglobin concentration (tHb) were examined during continuous (CR) and interval (INT) running. In a repeated measures design, 10 subjects twice performed 30 min of CR at 70% of their peak treadmill velocity, followed by 10 bouts of INT at 100%. Between trial reliability of mean and amplitude changes in TOI and tHb during CR were determined. Muscle de-oxygenation and re-oxygenation rates during INT were calculated using 3 analytical methods; i) linear modelling, ii) minimum and maximum values during work/rest intervals, and iii) mean values during work/rest intervals. Reliability was assessed using coefficient of variation (CV; %). During CR, mean TOI was more reliable (3.5%) compared with TOI amplitude change (34.7%), while mean tHb (12%) was similar to both absolute (9.2%) and relative (10.2%) amplitude changes. During INT, de-oxygenation rates analysed via linear modelling produced the lowest CV (7.2%), while analysis using min-max values produced the lowest CV (9.3%) for re-oxygenation rates. In conclusion, while the variables demonstrated CVs lower than reported changes in training-induced adaptations and/or differences between athletes and controls (23-450%), practitioners are encouraged to consider the advantages/disadvantages of each method when performing their analysis.