Abstract
The use of near-infrared spectroscopy could be an interesting alternative to
other invasive or expensive methods to estimate the second lactate threshold.
Our objective was to compare the intensities of the muscle oxygen saturation
breakpoint obtained with the Humon Hex and the second lactate threshold in elite
cyclists. Ninety cyclists performed a maximal graded exercise test. Blood
capillary lactate was obtained at the end of steps and muscle oxygenation was
continuously monitored. There were no differences (p>0.05) between
muscle oxygen oxygenation breakpoint and second lactate threshold neither in
power nor in heart rate, nor when these values were relativized as a percentage
of maximal aerobic power or maximum heart rate. There were also no differences
when men and women were studied separately. Both methods showed a highly
correlation in power (r=0.914), percentage of maximal aerobic power
(r=0.752), heart rate (r=0.955), and percentage of maximum heart
rate (r=0.903). Bland-Altman resulted in a mean difference of
0.05±0.27 W·kg–1, 0.91±4.93%,
0.63±3.25 bpm, and 0.32±1.69% for power, percentage of
maximal aerobic power, heart rate and percentage of maximum heart rate
respectively. These findings suggest that Humon may be a non-invasive and
low-cost alternative to estimate the second lactate threshold intensity in elite
cyclists.
Key words
muscle oxygen saturation - nirs - humon hex - anaerobic threshold - exercise intensity - cycling
