Muscle biopsy and muscle fiber hypercontraction: a brief review

Abstract

The percutaneous muscle biopsy technique is an important tool used in exercise and applied physiology to study human skeletal muscle structure, adaptation, and regeneration. One important use of this technique has been the assessment of ultrastructural muscle damage, especially in tissue samples obtained following strenuous exercise protocols, often involving eccentric muscle actions. In this brief review, we define and describe hypercontracted fibers, and outline how such fibers may adversely affect the interpretation of muscle damage from fixed tissue. Evidence suggests that hypercontracted fibers present in healthy skeletal muscle samples are likely to be artifacts related to the muscle biopsy procedure, as opposed to intrinsic degeneration present prior to the biopsy. When hypercontracted fibers are noted as being intrinsic to a muscle sample (e.g., in myopathy or following an extreme eccentric stimulus), such fibers are generally associated with the infiltration of inflammatory cells, indicative of a regenerative response. In contrast, hypercontracted fibers resulting from the biopsy procedure are not typically associated with an inflammatory response. The major sources of hypercontracted fibers are outlined and recommendations for their interpretation are discussed.

Cytokine and satellite cell responses to muscle damage: interpretation and possible confounding factors in human studies

“…There was some evidence of damage to the basal lamina, which may have been induced by phagocytosis (Armstrong et al 1991). Roth et al (2000) suggested that muscle biopsy samples should be viewed with caution when quantifying muscle damage, since the needle biopsy procedure and processing itself can result in muscle damage, specifically hypercontraction of fibers. After reviewing the literature Roth et al (2000) concluded that hypercontracted fibers in vivo are usually accompanied by signs of necrosis whereas hypercontracted fibers without necrosis are the result of the biopsy procedure.…”

Lesions of rat skeletal muscle after local block of acetylcholinesterase and neuromuscular stimulation

“…The most valid argument against biopsy artifacts is assumed to be the presence of leukocyte infiltrations (28). In the present investigation, no infiltrations were found, but because no specific staining for leukocytes was performed, accumulations of a few leukocytes could have been overlooked.…”

“…An area was defined as abnormally (or regionally) contracted when only part of a muscle fiber was contracted and particularly if the sarcomeres became progressively shorter until the A bands were closer together than expected in a maximum physiological contraction (cf., Ref. 28). For evaluation purposes, a sarcomere length of 40-60% of that of neighboring normal fibers was accepted as abnormally contracted (14).…”

Muscle Quality in Aging: a Multi-Dimensional Approach to Muscle Functioning with Applications for Treatment

“…This muscle sample can be processed and analyzed for muscle cell histology, including fiber type, arrangement, and organization using microscopy techniques. In spite of the ability of electron microscopy (EM) to provide important qualitative information regarding muscle ultrastructure, this classical approach can be confounded by significant contraction artifacts associated with tissue fixation [147]. Moreover, the very nature of EM analysis, whereby individual ultrathin 2-dimensional sections are studied, precludes any meaningful quantitative analysis addressing changes taking place within a complex 3-dimensional tissue [148].…”