title: Acute changes in hamstrings musculo-articular dissipative properties induced by cyclic and static stretching.
abstract: This study was designed to measure changes in musculo-articular dissipative properties related to viscosity that were induced by passive cyclic and static stretching. Musculo-articular dissipative properties were assessed by calculating a dissipation coefficient using potential elastic energies stored and restituted during cyclic stretching. Eight subjects performed five passive knee extensions/flexions cycles on a Biodex dynamometer at 5 degrees . s (-1) to 80 % of their maximal range of motion before and after a static stretching protocol. Electromyographic activity from the hamstring muscles was monitored and remained constant during cyclic stretching and after static stretching (p > 0.05). The dissipation coefficient decreased during cyclic stretching (- 28.8 +/- 6.0 %, p < 0.001), while it was slightly increased after static stretching (+ 3.8 +/- 5.0 %, p = 0.037). The findings showed that energy stored and energy restituted decreased during cyclic stretching and after static stretching (p < 0.05). During unloading, passive torque remained constant during cyclic stretching, but was decreased after static stretching. The findings indicate that musculo-articular dissipative properties were primarily affected by a single cycle of motion, and were not influenced by static stretching procedures. The decrease in dissipation coefficient following cyclic motion indicates that the musculo-articular system displays thixotropic behavior.
authors.affiliation: Université de Nantes, Nantes Atlantique Universités, Laboratoire Motricité, Interactions, Performance, JE 2438, UFR STAPS, Nantes, France.
authors.forename: A
authors.initials: A
authors.lastname: Nordez
authors.forename: P
authors.initials: P
authors.lastname: McNair
authors.forename: P
authors.initials: P
authors.lastname: Casari
authors.forename: C
authors.initials: C
authors.lastname: Cornu
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D004576:Electromyography; D005080:Exercise Test; D006801:Humans; D007717:Knee / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction; D052580:Muscle Stretching Exercises / Q000379:methods*; D018482:Muscle, Skeletal; D016059:Range of Motion, Articular; D013314:Stress, Mechanical