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A NIRS‐derived Skeletal Muscle Oxygen Consumption Method Accurately Reflects the Gold Standard Direct Fick Method during Single‐leg Knee Extension Exercise
Author(s) -
Craig Jesse C.,
Broxterman Ryan M.,
BarretO'Keefe Zachary,
Wray D. Walter,
Barstow Thomas J.,
Richardson Russell S.,
Trinity Joel D.
Publication year - 2022
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2022.36.s1.r5550
Subject(s) - gold standard (test) , skeletal muscle , medicine , leg muscle , blood flow , femoral artery , cardiology , vo2 max , chemistry , anatomy , heart rate , blood pressure , physical medicine and rehabilitation
Background Quantifying the oxygen consumption (V̇O 2 ) of skeletal muscle, which represents the largest metabolically‐active tissue mass, is an important assessment in exercise physiology. The gold standard for quantifying muscle V̇O 2 in the exercising human is the direct Fick method, however, technical challenges (e.g. arterial catheter insertion) preclude the widespread use of this technique, justifying the need for alternative approaches for the quantification of muscle V̇O 2 . Recently, we developed a noninvasive method of quantifying muscle V̇O 2 using Doppler ultrasound measurements of blood flow (Q̇) and near‐infrared spectroscopy (NIRS)‐derived deoxygenated‐[Heme] in a modified Fick method calculation, but, to date, this has not been validated against the gold standard method. Purpose and Hypotheses Therefore, the purpose of this investigation was to compare NIRS‐derived and direct Fick quantification of muscle V̇O 2 at multiple levels of single‐leg knee‐extensor exercise. We tested the hypotheses that: 1) the muscle V̇O 2 assessed by direct Fick and the NIRS‐derived muscle V̇O 2 would not be statistically different from each other across work rates, and 2) the V̇O 2 assessed by the two techniques would be strongly related. Methods Seven healthy young volunteers (3 women, 4 men; 24 ± 5 years) performed an incremental work rate test on a dynamic single‐leg knee‐extensor ergometer. Measurements of femoral artery Q̇ (Doppler ultrasound), vastus lateralis deoxygenated‐[Heme] (NIRS), and femoral artery and vein oxygen content were taken at rest, 0, 5, 10, 15, and 20 Watts (W) and used to estimate direct Fick and NIRS‐derived muscle V̇O 2 . Results NIRS‐derived V̇O 2 was not different from direct Fick V̇O 2 at any point (rest: 45 ± 21 vs 25 ± 17 ml/min; 0 W: 153 ± 70 vs 133 ± 68 ml/min; 5 W: 188 ± 81 vs 160 ± 65 ml/min; 10 W: 242 ± 123 vs 214 ± 91 ml/min; 15 W: 279 ± 131 vs 247 ± 89 ml/min; 20 W: 343 ± 163 vs 319 ± 122 ml/min; all P = 0.26 – 0.44). Muscle V̇O 2 determined by the two techniques was strongly related (r 2 : 0.97 ± 0.03) with a slope of 1.1 ± 0.3 and Y‐intercept of ‐21 ± 22 ml/min. Discussion Taken together, these findings indicate that the NIRS‐derived, noninvasive assessment of skeletal muscle V̇O 2 accurately reflects the gold standard quantification of muscle V̇O 2 over a range of work rates (with a constant ≍20 ml/min offset). This investigation provides the first evidence to support the use of the NIRS‐derived muscle V̇O 2 estimate during free‐flow conditions (i.e. not using venous or arterial occlusions like previous work), introducing a novel, noninvasive technique to quantify exercising skeletal muscle V̇O 2 .