title: Changes in tendon stiffness and running economy in highly trained distance runners.
abstract: The purpose of this study was to determine if changes in triceps-surae tendon stiffness (TST K) could affect running economy (RE) in highly trained distance runners. The intent was to induce increased TST K in a subgroup of runners by an added isometric training program. If TST K is a primary determinant of RE, then the energy cost of running (EC) should decrease in the trained subjects. EC was measured via open-circuit spirometry in 12 highly trained male distance runners, and TST K was measured using ultrasonography and dynamometry. Runners were randomly assigned to either a training or control group. The training group performed 4 × 20 s isometric contractions at 80% of maximum voluntary plantarflexion moment three times per week for 8 weeks. All subjects (V(O)₂(max)) = 67.4 ± 4.6 ml kg(-1) min(-1)) continued their usual training for running. TST K was measured every 2 weeks. EC was measured in both training and control groups before and after the 8 weeks at three submaximal velocities, corresponding to 75, 85 and 95% of the speed at lactate threshold (sLT). Isometric training did neither result in a mean increase in TST K (0.9 ± 25.8%) nor a mean improvement in RE (0.1 ± 3.6%); however, there was a significant relationship (r(2) = 0.43, p = 0.02) between the change in TST K and change in EC, regardless of the assigned group. It was concluded that TST K and EC are somewhat labile and change together.
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
authors.forename: Jared R
authors.initials: JR
authors.lastname: Fletcher
authors.forename: Shane P
authors.initials: SP
authors.lastname: Esau
authors.forename: Brian R
authors.initials: BR
authors.lastname: MacIntosh
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology; D004548:Elasticity / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D005080:Exercise Test; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D011897:Random Allocation; D012420:Running / Q000502:physiology*; D013710:Tendons / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D019344:Lactic Acid