Clinical Scenario: ReBound is a portable shortwave diathermy unit used to heat tissues using the same principle as induction drum shortwave diathermy. It is unclear if ReBound can vigorously (4°C) heat intramuscular tissue as efficiently as other thermal agents. Clinical Question: In adults (P), is ReBound diathermy (I) compared with other thermal agents (C) effective at increasing intramuscular tissue temperature by 4°C (O)? Summary of Key Findings: (1) Three studies were included for review, all randomized crossover studies. (2) All studies agreed ReBound does not achieve vigorous (4°C) heating effects during a 30-minute treatment to the triceps surae muscle (depth = 1 and 3 cm). (3) Studies agreed that the heat generated by ReBound dissipates slower than (P < .001) or similar to pulsed shortwave diathermy at 3 cm and faster than moist hot packs (P < .001) at 1 cm. (4) One study found that intramuscular tissue temperatures increased more with ReBound Clinical ScenarioHeat is used to accelerate the metabolic rate, decrease muscle spasm, decrease pain, increase blood flow, reduce chronic inflammation, and encourage tissue elongation. 1-4 Modalities used to raise tissue temperature include warm whirlpools, moist hot packs (MHPs), paraffin bath, therapeutic ultrasound, and pulsed shortwave diathermy (PSWD). These modalities can be separated into superficial and deep modalities according to their depth of penetration. Superficial modalities heat tissues 1 cm deep and include MHP, warm whirlpools, and paraffin baths. 2 Deep modalities heat tissues 3 cm deep and include shortwave diathermy (SWD) and therapeutic ultrasound. 2 The physiological effects created by the thermal agent is determined based on the degree of intramuscular temperature increase, duration of temperature increase, size of the area being treated, and rate of temperature rise. 2 Mild heating of the tissue is a 1°C increase, which increases the metabolic rate of the heated tissues. 1 Moderate heating is a 2°C to 3°C increase that causes a more significant metabolic effect, reduced muscle spasm and pain, and increased circulation to dissipate the heat. 1 Vigorous heating is a 4°C increase that causes an increase in metabolic rate, improved blood flow, reduced muscle spasm and pain, and altered viscoelastic properties of collagen. 1-3 These benefits allow a clinician to stretch patients more efficiently because the collagen is more extensible after a 4°C increase. 1,3 Clinicians can administer SWD in pulsed or continuous modes. SWD produces an oscillating electromagnetic field that is considered to induce movement of ions, molecule distortion, and eddy current creation within the field. The oscillations result in the thermal effects discussed previously. SWD has the added benefit of being able to heat large areas, such as the gastrocnemius. This ability makes it a more efficacious treatment than ultrasound for treating large areas. According to the evidence, the treatment area for therapeutic ultrasound should be no more than 2 to 3 times the effectiv...