Physiological Properties of Thermal Modalities (2)

Physiological Properties of Physiological Properties of Thermal Modalities (2)Thermal Modalities (2)

1. Haemodynamic Effects:1. Haemodynamic Effects:

Vasodilation Vasodilation

Increases the rate of blood flow (locally and Increases the rate of blood flow (locally and systemically)systemically)

It is increases more locallyIt is increases more locally

Physiological Effects of HeatPhysiological Effects of Heat

11 . .Haemodynamic EffectsHaemodynamic Effects::

It occurs due to:It occurs due to:

A.A. Direct activationDirect activation on the smooth muscles on the smooth muscles of blood vesselsof blood vessels

B.B. Indirect activationIndirect activation

Effect on spinal cord on the grey matter Effect on spinal cord on the grey matter smooth musclesmooth muscle

Sympathetic nervous system Sympathetic nervous system vasodilation vasodilation

11 . .Haemodynamic EffectsHaemodynamic Effects::

No increase in the temperature of most No increase in the temperature of most musclesmuscles

Protect body from excessive damageProtect body from excessive damage

Convection reduce the risk of burningConvection reduce the risk of burning

22 . .Neuromuscular EffectsNeuromuscular Effects::

A.A. Change in nerve conduction velocity and Change in nerve conduction velocity and firing rate:firing rate:

Change in nerve conduction velocity (Change in nerve conduction velocity (N.V.C)N.V.C) Decrease conduction latency (in sensory & Decrease conduction latency (in sensory &

motor nerves)motor nerves)

B.B. Increase pain thresholdIncrease pain threshold Direct Direct gating gating Indirect Indirect ischemia + ischemia + muscle spasm muscle spasm

33 . .Metabolic EffectsMetabolic Effects::

Increase metabolic rateIncrease metabolic rate Increase the rate of chemical reactions Increase the rate of chemical reactions

including enzymatic activityincluding enzymatic activity Up to 45°CUp to 45°C Increase rate of cellular biochemical Increase rate of cellular biochemical

reactionsreactions Increase OIncrease O2 2 uptakeuptake Increase healingIncrease healing

44 . .Alter Tissue ExtensibilityAlter Tissue Extensibility: :

Increase collagen extensibility Increase collagen extensibility Stretching the soft tissue without heating Stretching the soft tissue without heating

elastic deformationelastic deformation Stretching the soft tissue with heating Stretching the soft tissue with heating

plastic deformationplastic deformation Plastic deformation is due to the change in Plastic deformation is due to the change in

the viscoelasticity of collagen fibers + the the viscoelasticity of collagen fibers + the organization of collagen fibers organization of collagen fibers

40 - 45°C from 5 – 10 minutes (when 40 - 45°C from 5 – 10 minutes (when applying the agent apply for 15 minutes)applying the agent apply for 15 minutes)

Physiological Effects of HeatPhysiological Effects of Heat

Factors affecting these physiological effects:Factors affecting these physiological effects:

Size of the heated areaSize of the heated area Depth of absorption of specific radiationDepth of absorption of specific radiation Duration of heatingDuration of heating Frequency of treatmentFrequency of treatment Intensity of radiationIntensity of radiation Method of applicationMethod of application

Therapeutic Effects of HeatTherapeutic Effects of Heat

A.A. Pain control:Pain control:

Direct due to gatingDirect due to gating Indirect through healing, Indirect through healing, muscle spasm, muscle spasm, ischemia ischemia Skin temperatureSkin temperature Not recommended for acute inflammation.Not recommended for acute inflammation.

Remember! Applying hot agents to acute Remember! Applying hot agents to acute inflammation might cause destruction of the inflammation might cause destruction of the tissuetissue


B.B. Increase range of motion and decrease Increase range of motion and decrease joint stiffnessjoint stiffness

Soft tissue extensibilitySoft tissue extensibility Passive stretch (45°C for 5-10 minutes)Passive stretch (45°C for 5-10 minutes) Extensibility and viscoelasticity of particular Extensibility and viscoelasticity of particular

structures (joint capsule, ligaments ..etc) structures (joint capsule, ligaments ..etc) Superficial stretching (hot pack, infrared, paraffin)Superficial stretching (hot pack, infrared, paraffin) Deep stretching (ultrasound, shortwave diathermy)Deep stretching (ultrasound, shortwave diathermy)


C.C. Accelerate healingAccelerate healing

CirculationCirculation Enzymatic activityEnzymatic activity OO22, nutrients, remove waste products, nutrients, remove waste products In chronic inflammation (third & forth stages of In chronic inflammation (third & forth stages of

inflammation)inflammation) Inflammation & healing rapidly Inflammation & healing rapidly


D.D. Reduction of muscle spasmReduction of muscle spasm

Golgi tendon Golgi tendon Muscle spindleMuscle spindle

Sedative effectSedative effect

SleepingSleeping

Prophylaxis of pressure soresProphylaxis of pressure sores

Blood flowBlood flow

Risk of skin breakdownRisk of skin breakdown

Skin diseaseSkin disease

Like I.R.Like I.R.

Precursor for other treatment (Before stretching, Precursor for other treatment (Before stretching, exercises ,massage)exercises ,massage)

Contraindications of Superficial Contraindications of Superficial HeatingHeating

Acute injury or inflammationAcute injury or inflammation

Recent or potential hemorrhage Recent or potential hemorrhage

ThrombophlibitisThrombophlibitis

Impaired sensationImpaired sensation

Impaired mentatiionImpaired mentatiion

MalignancyMalignancy

I.R irradiation to eyesI.R irradiation to eyes damage of retina (use a goggle) damage of retina (use a goggle)

PrecautionsPrecautions

PregnancyPregnancy Impaired circulationImpaired circulation Poor thermal regulationPoor thermal regulation EdemaEdema chronic chronic hot agent + elevation hot agent + elevation Cardiac insufficiencyCardiac insufficiency Metal in the areaMetal in the area Over an open woundOver an open wound Over area where topical counterirritant hae Over area where topical counterirritant hae

recently been applied recently been applied

Adverse Effects of Thermo-therapyAdverse Effects of Thermo-therapy

A.A. BurnsBurns IntensityIntensity Too long time of applicationToo long time of application Patient fall asleepPatient fall asleep Contraindicating Contraindicating

B.B. FaintingFainting Vasodilation Vasodilation blood flow in the area treated blood flow in the area treated

blood pressure blood pressure

Adverse Effects of Thermo-therapyAdverse Effects of Thermo-therapy

A.A. BleedingBleeding

B.B. Skin and eye damage from I.R irradiationSkin and eye damage from I.R irradiation

Conductive Agents Conductive Agents Heat Methods of Application Heat Methods of Application

Two types of heat:Two types of heat:

Dry heat: increase surface temperatureDry heat: increase surface temperature Wet heat: increase temperature slightly deeperWet heat: increase temperature slightly deeper

Conduct techniques:Conduct techniques:

Superficial Superficial Deep Deep


Superficial contact heat depends on:Superficial contact heat depends on:

Intensity of heat Intensity of heat

Length of exposure to heatLength of exposure to heat

Thermal medium for surface heatThermal medium for surface heat


Heating tempreture 40 – 45°CHeating tempreture 40 – 45°C

Above this level Above this level burning burning

Below this level Below this level mild effect mild effect

Maximum elevation of skin temperature within Maximum elevation of skin temperature within 6-8 minutes6-8 minutes

Deep contact Deep contact deep heat modalities deep heat modalities

Good Luck Good Luck

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Physiological Properties of Thermal Modalities (2)