The objective of this study was to measure and monitor changes in the Achilles tendon mechanical properties and force production capability of triceps surae muscles after 4 weeks of limb suspension and 6 weeks of physical rehabilitation. Five healthy volunteers underwent unilateral lower limb suspension followed by weekly physiotherapy. A velocity encoded, phase contrast magnetic resonance imaging (VE-PC-MRI) technique was used to estimate the tendon strain as a function of force produced during the submaximal isometric contractions. Following limb suspension, triceps surae muscle strength decreased to 53.2 ± 15.6% (mean ± SD) of the pre-suspension level (p<0.05). Young's modulus estimated from the slope of the tendon stress-strain relation decreased by 17.1% (140.50 ± 29.33 MPa to 119.95 ± 36.07 MPa, p < 0.05) while the tendon transition point, reflecting the "toe-region", increased by 55.7% (2.2 ± 1.0% to 3.4 ± 1.24%). Muscle strength, tendon stiffness, and transition point recovered to pre-suspension levels by the end of 6 weeks of rehabilitation. Calcaneus movement was found to be significant during the 'isometric' contraction accounting for 52.13 ± 7.63% of the tendon displacement. Tendon cross sectional area determined from anatomical MR axial images remained unchanged, suggesting that the altered tendon elastic modulus and transition point were largely due to material deterioration. The increase in the transition point following chronic unloading as measured by the VE-PC-MRI technique has not been previously reported and offers new insights into the biomechanical changes that may occur in the tendon crimp structure.