Micro-biopsies: a less invasive technique for investigating human muscle fiber mechanics
The Journal of experimental biology
The Company of Biologists
School of Medical and Health Sciences
United States National Strength and Conditioning Association (G1003733)
The purpose of this investigation was to demonstrate that muscle fiber mechanics can be assessed on micro-biopsies obtained from human medial gastrocnemii. Three micro-biopsy samples were collected from female dancers (n = 15). Single fibers and fiber bundles were isolated and passively stretched from 2.4 to 3.0 µm at 0.015 and 0.04 µm s - 1 (n = 50 fibers total) and in five increments at 0.12 µm s - 1 (n = 42 fibers total). Muscle fibers were then activated isometrically at 2.4 µm (n = 4 fibers total) and 3.0 µm (n = 3 fibers total). Peak stress and steady-state stress were significantly greater (P < 0.0001) after stretching at 0.04 µm s - 1 than at 0.015 µm s - 1. Furthermore, peak stresses and steady-state stresses increased non-linearly with fiber length (P < 0.0001). We conclude that active and passive muscle fiber mechanics can be investigated using tissue from micro-biopsies.