title: Adaptive response in human skeletal muscle subjected to prolonged eccentric training.
abstract: The peripheral adaptation process associated with repeating eccentric training over a longer period of time was studied in m. vastus lateralis of eleven healthy males aged 24 +/- 4 years. The maximal dynamic concentric muscle strength was only slightly improved after 8 weeks of training. However, eccentric work capacity was dramatically increased (375%). A maximal eccentric stint immediately after fulfilled 8 weeks of training caused a selective glycogen depletion from the type 28 fibers. An increased number of type 2C fibers was observed. The ultrastructure analysis showed an essentially well-preserved fine structure. Volume density of mitochondria was somewhat higher in all fiber types after training. Z-band widths were not affected by eccentric training. It is concluded that skeletal musculature adapts itself in a functional manner to the extreme tension demands put on them. Improved coordination and reorganization of the contractile apparatus of muscle fibers are the determining mechanisms of this adaptation.
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D006801:Humans; D007717:Knee / Q000502:physiology; D008297:Male; D008931:Mitochondria, Muscle / Q000648:ultrastructure; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D010101:Oxygen Consumption; D010146:Pain / Q000209:etiology; D010806:Physical Education and Training; D013997:Time Factors