Relationship Between SMO2 Measured By NIRS And VO2 During Severe Intensity Intervals Of Running

Abstract

Near infrared spectroscopy (NIRS) has been shown to be a non-invasive wearable alternative to measured blood oxygenation levels. PURPOSE: The purpose was to determine whether a significant relationship exists between SMO2% and VO2 during the last two stages of treadmill interval testing past LT1. METHODS: Five volunteer members of a collegiate cross country team, (2 male, 3 female, 18.6+1.5 years, 169.4+10.9 cm, 61.3+7.8 kg) completed a maximal effort stepwise test to volitional exhaustion. Each subject was fitted with a calf sleeve containing the BSX NIRS Insight device, a ventilatory mask connected to the COSMED system, and a heart rate monitor. After a 5 minute recovery pace warm up, the subject ran four minute intervals, each increasing 0.4 mph in pace, with a one minute standing recovery period between each four minute stage. After blood lactate levels increased 1.5 millimoles from baseline levels, the final stage consisted of one-minute periods with the incline increased by 1 percent each minute, until volitional exhaustion ending the test. RESULTS: A Pearson correlation coefficient was calculated for the relationship between each participant’s SMO2% and VO2 during the final ramp stage, the 4 minute stage preceding the ramp stage, and for those two stages combined. A strong negative correlation was found for each participant’s total rest data, ranging from r = -0.660 to -0.925, and an average +/- standard deviation of -0.852+0.110. All correlations were significant at p<.01, indicating a significant linear relationship between the two variables. CONCLUSIONS: The study suggests that the BSX Insight device is a valid option for non-invasively measuring SMO2% during ventilatory maximal interval training. Given that the study concentrated on elite runners, further testing would need to be done to generalize the results to a larger population.Table: No title available.