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In JoVE (1)
Other Publications (4)
Articles by Shane P. Esau in JoVE
JoVE General
Procedures for Rat in situ Skeletal Muscle Contractile Properties
Faculty of Kinesiology, University of Calgary
This video demonstrates the surgical preparation and procedures needed to study the contractile responses of the rat medial gastrocnemius muscle preparation in situ. This preparation allows measurement of skeletal muscle contractile properties under physiological conditions. The animal is anesthetized and the muscle is separated from surrounding tissue at its distal end. The Achilles tendon is attached to a force transducer, allowing measurement of the muscle’s contractile response at 37 degrees C with an intact circulation.
Other articles by Shane P. Esau on PubMed
Economy of Running: Beyond the Measurement of Oxygen Uptake
The purpose of this study was to compare running economy across three submaximal speeds expressed as both oxygen cost (mlxkg(-1)xkm(-1)) and the energy required to cover a given distance (kcalxkg(-1)xkm(-1)) in a group of trained male distance runners. It was hypothesized that expressing running economy in terms of caloric unit cost would be more sensitive to changes in speed than oxygen cost by accounting for differences associated with substrate utilization. Sixteen highly trained male distance runners [maximal oxygen uptake (Vo(2max)) 66.5 +/- 5.6 mlxkg(-1)xmin(-1), body mass 67.9 +/- 7.3 kg, height 177.6 +/- 7.0 cm, age 24.6 +/- 5.0 yr] ran on a motorized treadmill for 5 min with a gradient of 0% at speeds corresponding to 75%, 85%, and 95% of speed at lactate threshold with 5-min rest between stages. Oxygen uptake was measured via open-circuit calorimetry. Average oxygen cost was 221 +/- 19, 217 +/- 15, and 221 +/- 13 mlxkg(-1)xkm(-1), respectively. Caloric unit cost was 1.05 +/- 0.09, 1.07 +/- 0.08, and 1.11 +/- 0.07 kcalxkg(-1)xkm(-1) at the three trial speeds, respectively. There was no difference in oxygen cost with respect to speed (P = 0.657); however, caloric unit cost significantly increased with speed (P < 0.001). It was concluded that expression of running economy in terms of caloric unit cost is more sensitive to changes in speed and is a more valuable expression of running economy than oxygen uptake, even when normalized per distance traveled.
Changes in Tendon Stiffness and Running Economy in Highly Trained Distance Runners
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.
