Achilles tendon and calf muscle strains are among the most frequent injuries in athletes, often occurring at the musculotendinous junction where blood supply is limited. Adequate vascularization is crucial for tendon healing, and impaired circulation leads to collagen degeneration and poor recovery. Capacitive–Resistive Electric Transfer (CRet), known clinically as Tecar therapy, delivers 300 kHz–1.2 MHz radiofrequency currents that induce both thermal effects (Joule heating) and bioelectrical effects (cellular stimulation), improving circulation and tissue regeneration. This study aimed to analyze, in a controlled cadaveric model, the temperature changes and current flow in the Achilles tendon, musculotendinous junction, and superficial calf tissues produced by different Tecar therapy protocols.
A cross-sectional cadaveric study was conducted using five fresh-frozen cadavers (10 legs) provided by the Universitat Internacional de Catalunya. Using a Wintecare T-Plus device, four 5-minute protocols were applied to each leg:
Thermocouples were inserted under ultrasound guidance into three sites: superficial calf tissue, Achilles tendon, and the musculotendinous junction. Temperature was recorded at 1-minute intervals during application and 5 minutes afterward. Current flow (A) was measured through impedance calculations.
All four protocols produced measurable rises in temperature at all tissue depths, with greater effects under high-power conditions. The high-power resistive (HPR) protocol generated the largest deep heating and current flow, while capacitive modes primarily warmed superficial tissues.
Temperature peaked at 5 minutes and dropped partially by 5 minutes post-application. The HPR mode increased Achilles tendon temperature to approximately 50 °C—double the baseline value—and induced the highest deep current density, demonstrating its superior energy transfer efficiency.
The findings confirm that resistive modes penetrate deeper and deliver stronger current densities than capacitive modes, which act mainly on hydrated superficial tissues. Low-power applications produced minimal heating yet maintained measurable current flow, indicating bio-stimulatory (non-thermal) potential ideal for acute inflammatory stages where warmth should be limited but cell regeneration is desired. Conversely, high-power resistive settings generated substantial deep thermal effects suited to chronic tendinopathies or fibrotic scars, where heat and viscoelastic changes enhance collagen remodeling. These observations align with prior clinical evidence that CRet therapy improves circulation, oxygenation, and healing in living tissues.
Tecar therapy using 448 kHz CRet currents effectively induces both thermal and non-thermal effects depending on energy level and electrode mode.
These results provide foundational data on tissue-specific energy transfer, validating the Wintecare T-Plus as an effective modality for both acute and chronic Achilles-related pathologies
