The Assessment of Muscle Oxygen Saturation in Students During Maximal VO2 Exercise and High Intensity Intervals

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)
Justin Simmons (Creator)
East Carolina University (ECU )
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Abstract: The advancement of human performance benefits from state-of-the-art technology to improve the ability to monitor and evaluate physiological adaptations in athletes. Previously validated as a reliable tool for measuring muscle oxygenation , near-infrared spectroscopy (NIRS) has evolved into a more portable platform capable of being used in a variety of settings. This has expanded the usefulness of NIRS and created an increase in explorations to evaluate its capabilities and applications in exercise science. With the emergence of new portable devices , the need to assess the capabilities and potential of such exercise tools is important. One such example of a portable NIRS device advertised to athletes and the military is the MOXY monitor. Purpose: To our knowledge , no studies exist that have examined the output produced by the MOXY monitor compared to other more established variables during high intensity intervals. Therefore , the purpose of this experiment was to evaluate the output provided by the MOXY monitors (SmO2) by comparing SmO2 to more established exercise variables including VO2 , heart rate and blood lactate (BL) to determine if the values agree with physiological expectations. We predicted that the SmO2 would demonstrate an inverse relationship to other measured variables including HR , VO2 and BL. Eg. As SmO2 decreased , HR , VO2 and BL would increase and peak HR , VO2 , BL values would coincide with SMO2 troughs. Methods: Six endurance-trained East Carolina University students , aged 21±2 years completed a VO2 max test followed by 6 high-intensity 30-second sprint intervals at 125% of VO2 max wattage on a cycle ergometer. SmO2 was measured using MOXY monitors (Fortiori Design LLC. , MN , USA) placed on the quadriceps muscles as well as the left deltoid. HR was monitored using a Garmin FR70 watch (Garmin Ltd. , Switzerland) and VO2 obtained using a Parvomedic TrueOne 2400 metabolic cart (Parvo Medics , UT , USA). BL was collected within 5 seconds of the completion of each of the 6 high intensity intervals using a Lactate Plus Meter (Sports Research Group Inc.). SmO2 and VO2 and SmO2 and HR were plotted over time to present a graphical illustration demonstrating the relationships among changes in oxygen saturation and the change with VO2 and HR. BL and SmO2 were presented using tables to display changes in BL and SmO2 as the intervals progressed. Results: All participants had a VO2 max [greater than]30ml/kg/min and no musculoskeletal injuries in the previous 3 months were reported. Body fat percentages were within normal ACSM guidelines and participants reported meeting USDA guidelines for fruit and vegetable intake (Dwyer , 2008 , During each of the six intervals , SmO2 was shown to decrease as both VO2 and HR increased. Troughs in SmO2 did not consistently align with peaks in VO2 and HR , as SmO2 tended to reach troughs about 10 seconds after the completion of many intervals. VO2 also demonstrated peaks at 20 and 40-seconds following interval completion. Patterns in BL were unable to be evaluated due to inadequate BL collection. Only two participants had all 6 BL values successfully obtained while another had 5. These participants demonstrated a pattern of increasing with intervals 1-4 followed by a plateau or decline in the final intervals. Conclusion: The findings from this study support the hypothesis that SmO2 would demonstrate an inverse relationship compared to HR and VO2 during high intensity intervals. Eg. As SmO2 decreased during the intervals , both HR and VO2 increased. However , peak HR and VO2 values did not coincide with SmO2 troughs. A delay of about 10 seconds was observed in SmO2 troughs and a 20 to 40-second delay was seen in peak VO2 and HR values. Further research is needed to investigate this finding as it is unclear as to the cause of the delays. Despite previous research showing an inverse relationship among muscle oxygenation and BL , the present study was unable support this relationship as insufficient BL samples were available for evaluation. The results obtained from this study suggests the MOXY monitors may provide reliable output as the inverse relationships among SmO2 and HR and SmO2 and VO2 agree with physiological expectations , despite peaks and troughs not coinciding. Further research will be needed to explore the relationships among these variables and to further assess the MOXY monitor as a tool for exercise training.

Additional Information

Language: English
Date: 2017
SmO2, blood lactate, heart rate, muscle oxygenation, volume of oxygen

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