Effect of Capacitive and Resistive electric transfer on haemoglobin saturation and tissue temperature

Background / Purpose

Thermotherapy is widely used in rehabilitation to improve circulation and relieve pain, yet superficial methods such as hot packs often fail to heat deep tissues effectively. Capacitive and Resistive Electric Transfer (CRet), operating at 448 kHz, delivers radiofrequency energy capable of increasing temperature and oxygenation in deeper tissue layers. This study compared the physiological effects of CRet versus conventional hot pack therapy (HP) on haemoglobin saturation and tissue temperature in the lumbar region of healthy adults.

Methods

Thirteen healthy males (mean age 24.5 ± 3.0 years) completed three 15 minute treatments on separate days: active CRet, hot pack, and sham (inactive CRet). The Indiba® Active ProRecovery HCR902 device was used, applying 5 minutes in Capacitive mode and 10 minutes in Resistive mode at an intensity rated 6–7/10 on a thermal comfort scale. Haemoglobin saturation (oxy-Hb, deoxy-Hb, total-Hb) and tissue temperature were recorded at the skin surface and at 10 mm and 20 mm depths before, during, and up to 30 minutes post-treatment.

Results

Haemoglobin Oxygenation

• Oxy-Hb (µmol/L): Increased from 53.6 ± 7.0 at baseline to ~65.8–66.6 during the first 10 minutes after CRet treatment — a +22% rise, maintained for the full 30 minutes post-intervention.
• Total-Hb: Increased from 86.4 ± 9.0 to ~97.2 µmol/L after CRet (+12.5%), versus a smaller change in the hot pack group (+8%) and negligible change in the sham group.
• Deoxy-Hb: Remained stable (~31 µmol/L), confirming that the rise in total haemoglobin was due to increased oxygenated haemoglobin rather than venous pooling.
• The CRet group showed significantly higher oxy-Hb and total-Hb compared to both HP and sham across all time intervals (p < 0.016).

Tissue Temperature

• At 10 mm depth, temperature rose from 34.9 °C → 38.1 °C (+3.2 °C) immediately after CRet versus +2.8 °C with HP.
• At 20 mm depth, CRet increased temperature from 34.9 °C → 38.2 °C (+3.3 °C), significantly higher than HP at the same depth (p < 0.016).
• Deep temperature elevation persisted 30 minutes post-treatment, confirming sustained internal heating.

‍Conclusions

CRet therapy (Tecar) produced statistically significant increases in oxygenated and total haemoglobin, indicating improved local circulation and oxygen delivery, alongside superior deep thermal effects compared to traditional hot pack therapy. Mean oxy-Hb increased by roughly 12 µmol/L and total-Hb by 11 µmol/L after a single CRet session — a measurable physiological enhancement maintained for over 30 minutes. These results validate Tecar’s ability to induce deep, sustained oxygenation and perfusion improvements, supporting its use as an advanced thermotherapy for recovery and rehabilitation.