In Vivo Measurements of Glucose Uptake in Human Achilles Tendon During Different Exercise Intensities

Abstract

Muscular contraction and loading of adjacent tendons has been demonstrated to cause increased blood flow and metabolic activity in the peritendinous region. However, it is poorly known to what extent the human tendon itself takes up glucose during exercise. Thus, the purpose of this study was to measure tendon glucose uptake with increasing exercise intensity and to compare it to muscle glucose uptake at the same intensities. Eight young men were examined on three separate days during which they performed 35 min of cycling at 30, 55 and 75 % of VO2max, respectively. Glucose uptake was measured directly by positron emission tomography (PET) with 2-[ (18)F]fluoro-2-deoxyglucose ([18F]FDG). [18F]FDG was injected after 10 min of exercise that was continued for a further 25 min after the injection. PET scanning of the thigh and Achilles region was performed after the exercise. Glucose uptake of the Achilles tendon (AT) remained unchanged (7.1 +/- 1.5, 6.6 +/- 1.1, and 6.0 +/- 1.1 micromol.kg(-1).min(-1)) with the increasing workload, although the glucose uptake in m. quadriceps femoris simultaneously clearly increased (48 +/- 35, 120 +/- 35, and 152 +/- 74 micromol.kg(-1).min(-1), p < 0.05). In conclusion, the AT takes up glucose during exercise but in significantly smaller amounts than the skeletal muscle does. Furthermore, glucose uptake in the AT is not increased with the increasing exercise intensity. This may be partly explained by the cycle ergometry exercise used in the present study, which probably causes only a little increase in strain to the AT with increasing exercise intensity.

Accuracy of MRI technique in measuring tendon cross‐sectional area

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Tenomodulin is Required for Tendon Endurance Running and Collagen I Fibril Adaptation to Mechanical Load

“…A rise in blood-flow (Langberg et al, 1998), collagen-turnover (Langberg et al, 2000), glucose uptake (Hannukainen et al, 2005) and altered regulation of matrix metalloproteases (Koskinen et al, 2004) are detected in tendons during exercise. Tendons also adapt differently depending on the nature of the exercise.…”

Flexible mechanisms: the diverse roles of biological springs in vertebrate movement

“…The dynamic response of a tendon to loading has been demonstrated even in very short timescales. Recent studies have documented increased blood flow and metabolic energy consumption in tendons during periods of heavy exercise Hannukainen et al, 2005), illustrating the robust metabolic infrastructure available to promote changes in tendon mechanical properties.…”