Exercise induced changes in echo intensity within the muscle: a brief review
Echo intensity is the mean pixel intensity of a specific region of interest from an ultrasound image. This variable has been increasingly used in the literature as a physiological marker. Although there has been an increased interest in reporting changes in echo intensity in response to exercise, little consensus exists as to what a change in echo intensity represents physiologically. The purpose of this paper is to review some of the earliest, as well as the most up to date literature regarding the changes in echo intensity in response to exercise. Echo intensity has been used to measure muscle quality, muscle damage, acute swelling, and intramuscular glycogen. The changes in echo intensity, however, are not consistent throughout the literature and often times lead to conclusions that seem contrary to the physiologic effects of exercise. For example, echo intensity increases in conjunction with increases in strength, contrary to what would be expected if echo intensity was a marker of muscle quality/muscle damage. It is conceivable that a change in echo intensity represents a range of physiologic effects at different time points. We recommend that these effects should be determined experimentally in order to rule out what echo intensity might and might not represent. Until this is done, caution should be employed when interpreting changes in echo intensity with acute and chronic exercise.
KeywordsMuscle quality Edema Muscle damage Glycogen content Fluid shift Muscle swelling Ultrasound Intracellular Exercise
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
- 7.Yoshiko A, Tomita A, Ando R et al (2018) Effects of 10-week walking and walking with home-based resistance training on muscle quality, muscle size, and physical functional tests in healthy older individuals. Eur Rev Aging Phys Act 15:13. https://doi.org/10.1186/s11556-018-0201-2 CrossRefPubMedPubMedCentralGoogle Scholar
- 8.Yoshiko A, Kaji T, Sugiyama H et al (2019) Twenty-four months’ resistance and endurance training improves muscle size and physical functions but not muscle quality in older adults requiring long-term care. J Nutr Health Aging 23:564–570. https://doi.org/10.1007/s12603-019-1208-8 CrossRefPubMedGoogle Scholar
- 22.Jajtner A, Hoffman J, Scanlon T et al (2013) Performance and muscle architecture comparisons between starters and nonstarters in National Collegiate Athletic Association Division I women’s soccer. J Strength Cond Res 27:2355–2365. https://doi.org/10.1519/JSC.0b013e31829bd7c5 CrossRefPubMedGoogle Scholar
- 36.Fritsch CG, Dornelles MP, Severo-Silveira L et al (2016) Effects of low-level laser therapy applied before or after plyometric exercise on muscle damage markers: randomized, double-blind, placebo-controlled trial. Lasers Med Sci 31:1935–1942. https://doi.org/10.1007/s10103-016-2072-y CrossRefPubMedGoogle Scholar
- 46.Fukumoto Y, Tateuchi H, Ikezoe T et al (2014) Effects of high-velocity resistance training on muscle function, muscle properties, and physical performance in individuals with hip osteoarthritis: a randomized controlled trial. Clin Rehabil 28:48–58. https://doi.org/10.1177/0269215513492161 CrossRefPubMedGoogle Scholar
- 51.Nosaka K, Newton M, Sacco P et al (2005) Partial protection against muscle damage by eccentric actions at short muscle lengths. Med Sci Sports Exerc 37:746–753. https://doi.org/10.1249/01.MSS.0000162691.66162.00 CrossRefPubMedGoogle Scholar
- 60.McGregor RA, Cameron-Smith D, Poppitt SD (2014) It is not just muscle mass: a review of muscle quality, composition and metabolism during ageing as determinants of muscle function and mobility in later life. Longev Healthspan. https://doi.org/10.1186/2046-2395-3-9 CrossRefPubMedPubMedCentralGoogle Scholar
- 67.Pillen S, Tak RO, Zwarts MJ et al (2009) Skeletal muscle ultrasound: correlation between fibrous tissue and echo intensity. Ultrasound Med Biol 35:443–446. https://doi.org/10.1016/j.ultrasmedbio.2008.09.016 CrossRefPubMedGoogle Scholar
- 70.Fujikake T, Hart R, Nosaka K (2009) Changes in B-mode ultrasound echo intensity following injection of bupivacaine hydrochloride to rat hind limb muscles in relation to histologic changes. Ultrasound Med Biol 35:687–696. https://doi.org/10.1016/j.ultrasmedbio.2008.10.008 CrossRefPubMedGoogle Scholar
- 71.Chen L, Nelson DR, Zhao Y et al (2013) Relationship between muscle mass and muscle strength, and the impact of comorbidities: a population-based, cross-sectional study of older adults in the United States. BMC Geriatr 13:74. https://doi.org/10.1186/1471-2318-13-74 CrossRefPubMedPubMedCentralGoogle Scholar