Muscle temperature transients before, during, and after exercise measured using an intramuscular multisensor probe

Abstract

Seven subjects (1 woman) performed an incremental isotonic test on a Kin-Com isokinetic apparatus to determine their maximal oxygen consumption during bilateral knee extensions (V˙o 2 sp). A multisensor thermal probe was inserted into the left vastus medialis (middiaphysis) under ultrasound guidance. The deepest sensor (tip) was located ∼10 mm from the femur and deep femoral artery (Tmu 10), with additional sensors located 15 (Tmu 25) and 30 mm (Tmu 40) from the tip. Esophageal temperature (Tes) was measured as an index of core temperature. Subjects rested in an upright seated position for 60 min in an ambient condition of 22°C. They then performed 15 min of isolated bilateral knee extensions (60% of V˙o 2 sp) on a Kin-Com, followed by 60 min of recovery. Resting Tes was 36.80°C, whereas Tmu 10, Tmu 25, and Tmu 40 were 36.14, 35.86, and 35.01°C, respectively. Exercise resulted in a Tes increase of 0.55°C above preexercise resting, whereas muscle temperature of the exercising leg increased by 2.00, 2.37, and 3.20°C for Tmu 10, Tmu 25, and Tmu 40, respectively. Postexercise Tes showed a rapid decrease followed by a prolonged sustained elevation ∼0.3°C above resting. Muscle temperature decreased gradually over the course of recovery, with values remaining significantly elevated by 0.92, 1.05, and 1.77°C for Tmu 10, Tmu 25, and Tmu 40, respectively, at end of recovery ( P < 0.05). These results suggest that the transfer of residual heat from previously active musculature may contribute to the sustained elevation in postexercise Tes.