Improving the Efficiency of Mitochondrial Capacity Measurements Using Near Infrared Spectroscopy

Near Infrared Spectroscopy (NIRS) has been used to noninvasively measure muscle mitochondrial capacity. Previous protocols have required 2 tests and up to 50 cuff inflations. PURPOSE Develop a new protocol for testing mitochondrial capacity that decreases the number of ischemic cuffs, increases comfort for participants, and improves curve fitting of the data, all while retaining reliability of the test. METHODS The forearm flexor muscles of sixteen young, healthy individuals were tested (23 ± 4.1 years). A resting metabolism value was collected after 5 min of complete rest before and after the test. The test involved 4 sets of 6 ischemic cuff inflations, preceded by 30s of electrically induced twitch contractions. Analysis was performed on mitochondrial metabolic rates using a customized MATLAB program. RESULTS The post‐test resting metabolism values were higher than the pre‐test resting values (−0.038 ± 0.02, −0.018 ± 0.01, optical density units P<0.01). There was no significant difference in the mitochondrial capacity for the four sets (1.50 ± 0.51, 1.42 ± 0.54, 1.26 ± 0.41, 1.29 ± 0.47, P=0.76). CONCLUSION The main finding of this study is that a test of mitochondrial capacity using four sets of 6 cuffs can be performed in less time (t ≈ 25 min) than two sets of 22 cuffs (t ≈ 45 min). While the use of a post‐test resting metabolism value did slightly lengthen the time needed to complete the study in relation to using the pre‐test value, this value appeared to be more accurate than using the pre‐test resting metabolism. The use of the post‐test resting values provided lower residuals and better agreement with previous data on the forearm muscles. Improved data collection can enhance the usefulness of NIRS based measurements of mitochondrial capacity. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .