Abstract
.A quantitative and dynamic analysis of skeletal muscle structure and function can guide training protocols and optimize interventions for rehabilitation and disease. While technologies exist to measure body composition, techniques are still needed for quantitative, long-term functional imaging of muscle at the bedside. We evaluate whether diffuse optical spectroscopic imaging (DOSI) can be used for long-term assessment of resistance training (RT). DOSI measures of tissue composition were obtained from 12 adults before and after 5 weeks of training and compared to lean mass fraction (LMF) from dual-energy X-ray absorptiometry (DXA). Significant correlations were detected between DXA LMF and DOSI-measured oxy-hemo/myoglobin, deoxy-hemo/myoglobin, total-hemo/myoglobin, water, and lipid. RT-induced increases of in oxy-hemo/myoglobin (, ) and total-hemo/myoglobin (, ) from the medial gastrocnemius were detected with DOSI and accompanied by increases in lean soft tissue mass (, ) and increases in 1 rep-max strength (, ). DOSI measures of vascular and/or muscle changes combined with correlations between DOSI and DXA suggest that quantitative diffuse optical methods can be used to evaluate body composition, provide feedback on long-term interventions, and generate new insight into training-induced muscle adaptations.
Highlights
Skeletal muscle plays a major role in whole-body protein stability and maintenance and is an important measure of an individual’s ability to maintain overall health, optimize athletic performance, and overcome injury.[1,2,3] Researchers have demonstrated correlations between decreased muscle mass and strength with obesity, chronic diseases such as heart failure and cancer, the development of insulin resistance and diabetes, and osteoporosis.[4]
Three participants were not able to contribute to the diffuse optical spectroscopic imaging (DOSI) results due to system malfunction, so the DOSI data are composed of 12 participants (8 male, 4 female)
near-infrared spectroscopy (NIRS) has been widely used in exercise and skeletal muscle research,[6,7,8,9,10,11,12,13,28,29,30,31,32,33] but there is a lack of research using NIRS to examine how tissue chromophores change during longterm, longitudinal studies as a result of resistance training (RT) protocols
Summary
Skeletal muscle plays a major role in whole-body protein stability and maintenance and is an important measure of an individual’s ability to maintain overall health, optimize athletic performance, and overcome injury.[1,2,3] Researchers have demonstrated correlations between decreased muscle mass and strength with obesity, chronic diseases such as heart failure and cancer, the development of insulin resistance and diabetes, and osteoporosis.[4] As a result, the development of quantitative, bedside, and wearable technologies for characterizing muscle composition and assessing long-term changes and interventions would be broadly impactful in precision medicine and personal health. DXA can noninvasively scan the body and quantify composition, i.e., the amount of fat, lean soft tissue, and bone mineral content present in specific tissue compartments.[5] Despite the utility of DXA measurements, DXA machines are not portable and are unable to assess perfusion and oxygen saturation, both of which are important in exercise and health assessments. A measurement of lean soft tissue mass is not a direct means of quantifying
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