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Sarcomere lengths in human extensor carpi radialis brevis measured by microendoscopy
Author(s) -
Cromie Melinda J.,
Sanchez Gabriel N.,
Schnitzer Mark J.,
Delp Scott L.
Publication year - 2013
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.23760
Subject(s) - sarcomere , anatomy , muscle fibre , titin , physics , medicine , skeletal muscle , myocyte , endocrinology
Second‐harmonic generation microendoscopy is a minimally invasive technique to image sarcomeres and measure their lengths in humans, but motion artifact and low signal have limited the use of this novel technique. Methods We discovered that an excitation wavelength of 960 nm maximized image signal; this enabled an image acquisition rate of 3 frames/s, which decreased motion artifact. We then used microendoscopy to measure sarcomere lengths in the human extensor carpi radialis brevis with the wrist at 45° extension and 45° flexion in 7 subjects. We also measured the variability in sarcomere lengths within single fibers. Results Average sarcomere lengths in 45° extension were 2.93±0.29 μm (±SD) and increased to 3.58±0.19 μm in 45° flexion. Within single fibers the standard deviation of sarcomere lengths in series was 0.20 μm. Conclusions Microendoscopy can be used to measure sarcomere lengths at different body postures. Lengths of sarcomeres in series within a fiber vary substantially. Muscle Nerve , 48: 286–292, 2013