15.1 Cryotherapy & Thermotherapy
Key Takeaways
- Energy transfer: conduction (ice bag, hydrocollator, paraffin), convection (whirlpool, CWI, fluidotherapy), conversion (ultrasound, diathermy), radiation (infrared), evaporation (vapocoolant).
- Ice is traditional for acute pain and swelling via slower nerve conduction and vasoconstriction; it does not heal ligaments faster. Limit time for frostbite and nerve injury. Hunting/CIVD is taught with caveats.
- Typical teaching parameters: ice bag about 15–20 minutes; ice massage 5–10 minutes through CBAN; hydrocollator packs about 158–167°F with 6–8 towel layers for 15–20 minutes, skin check at about 5 minutes.
- Cryotherapy contraindications include Raynaud phenomenon, cold urticaria, regenerating peripheral nerve, open wound, and circulatory compromise. Heat is contraindicated over acute inflammation, impaired sensation, malignancy, and DVT.
- Trap: hydrocollator pack on bare skin, or ice over a superficial nerve (fibular head, cubital tunnel) for 40 minutes. Recovery CWI is not the same protocol as ice-water immersion for exertional heat stroke.
Quick Answer: Match the energy-transfer mode to the tool: conduction (ice bag, hydrocollator, paraffin), convection (whirlpool, cold-water immersion), conversion (ultrasound, diathermy), radiation (infrared), evaporation (vapocoolant). Ice is traditional for acute pain and swelling; it does not heal ligaments faster. Hydrocollator packs need about 6–8 towel layers. Trap: pack on bare skin, or ice a superficial nerve for 40 minutes.
Practice Analysis, 8th Edition (PA8) Domain IV, task 0404, asks the athletic trainer (AT) to administer therapeutic modalities and devices using evidence-based procedures and parameters. Thermal agents are not decorations on a treatment table. They change tissue temperature, nerve conduction, blood flow, and comfort. They also burn, freeze, and injure nerves when the screen, barrier, or clock is skipped.
How heat actually moves
Knight, Michlovitz, and Prentice-style modality texts all start here because the mode predicts depth, rate, and risk.
| Mode | Definition | Common AT examples |
|---|---|---|
| Conduction | Direct molecular collision between two materials in contact | Ice bag, gel pack, ice massage, hydrocollator pack, paraffin (solid-to-skin contact) |
| Convection | Heat carried by a moving fluid (air or water) across the skin | Cold or warm whirlpool, cold-water immersion (CWI), fluidotherapy |
| Conversion | Nonthermal energy converted to heat inside tissue | Therapeutic ultrasound (acoustic → thermal), shortwave diathermy (electromagnetic → thermal) |
| Radiation | Infrared electromagnetic energy; no contact required | Infrared lamp (less common in modern AT rooms) |
| Evaporation | Energy absorbed as a liquid becomes vapor | Vapocoolant spray; physiologic sweating |
Water conducts and convects far better than air. That is why a 55°F whirlpool feels harsher than 55°F air, and why wet clothing plus ice accelerates cooling. Fat insulates; a lean ankle cools faster than a thick thigh. Metal jewelry concentrates conduction—remove it.
Cryotherapy: what cold does, and what it does not
Therapeutic cooling abstracts heat from the body. Direct, well-supported effects:
- Analgesia. Nerve conduction velocity falls as tissue cools. A-delta and C-fiber traffic slows; the athlete reports numbness after the classic CBAN sequence (cold, burning, aching, numbness).
- Decreased local metabolic demand. Cooler tissue consumes less oxygen in the minutes after injury—the traditional rationale for limiting secondary hypoxic damage.
- Vasoconstriction of cutaneous vessels, which can slow (not abolish) local blood flow.
Evidence honesty: ice is a reasonable analgesic and a traditional adjunct for acute pain and swelling. It is not a proven accelerator of ligament healing. Do not tell a BOC vignette—or a parent—that 20 minutes of ice repairs an anterior talofibular ligament. Cochrane-style reviews of cryotherapy after soft-tissue injury support short-term pain relief more than faster structural healing. After heavy hypertrophy lifting, routine CWI can blunt muscle-protein signaling; do not ice every squat session as if cold were anabolic.
Common methods and textbook-conventional parameters
These numbers are commonly taught in Knight/Michlovitz/Prentice pathways. They are not FDA-labeled drug doses. Always check skin, and stop for wheals, mottling, or pain that is not the expected CBAN sequence.
| Method | Typical teaching parameters | Notes |
|---|---|---|
| Ice bag (crushed ice) | About 15–20 minutes; re-check skin; can repeat about every 1–2 hours acutely | Crushed ice stays near 32°F as it melts. A thin wet barrier is often used; gel packs that are colder than ice always need a barrier. |
| Ice massage | About 5–10 minutes over a small area, or until numbness | Excellent over a tendon or a bony contour. Stop at analgesia—do not keep grinding after the skin is numb. |
| Cold whirlpool | Often about 50–60°F (10–15.5°C) for 5–15 minutes for a distal extremity | Convection plus hydrostatic pressure. Watch for after-drop and for athletes who cannot get out independently. |
| CWI (recovery) | Commonly about 50–59°F (10–15°C) for about 10–15 minutes | Goal is soreness modulation after a match, not core cooling to 102°F. |
| CWI / ice-water immersion (exertional heat stroke) | About 35–59°F (1.7–15°C) until rectal temperature ≈ 38.9°C (102°F) (NATA EHI teaching) | Life-saving cooling. Different goal, different endpoint, different urgency than a recovery tub. |
| Game Ready / IPC cold | Device-set cold plus intermittent pneumatic compression; typical wraps 10–20 minutes | Combines conduction (cold water in the sleeve) with mechanical compression. Still screen DVT, open wounds, and cold contraindications. |
Vapocoolant spray is evaporation used for a few seconds before a stretch (spray-and-stretch). It cools skin, not a deep joint. Do not freeze the skin, and do not spray the face or open wounds.
Hunting response: taught concept, real caveats
Lewis (1930) described cold-induced vasodilation (CIVD)—the hunting response—as cyclic vasoconstriction then vasodilation in extremities (fingers, toes, ears) exposed to severe cold, classically every several minutes after an initial constrictive phase. Traditional AT teaching used that cycle to justify a 20-minute ice limit so the limb would not 'rewarm and swell.'
Teach it, then caveat it. CIVD is well documented in digits at very cold temperatures. An ice bag on a quadriceps for 20 minutes may never produce classic hunting. The reason to stop at about 15–20 minutes (and sooner over a bony prominence or a superficial nerve) is frostbite and neuropraxia, not because ice magically 'stops working' at minute 21. Do not ice for 40 minutes to 'get a deeper freeze.'
Frostbite risk rises with gel or chemical packs (can be well below 0°C), impaired circulation or sensation, very young or older patients, tight wraps that add ischemia, and bony prominences. White, waxy, insensate skin is an emergency—rewarm per protocol and get medical care; do not rub ice on it.
Thermotherapy: when heat is the tool
Superficial heat (about 1–2 cm) increases local blood flow, decreases spasm and pain, and can improve extensibility of collagen while the tissue is warm—so stretch during or immediately after heat, not an hour later. Heat is for subacute/chronic stiffness and spasm, not for a hot, swollen, acute sprain.
| Method | Typical teaching parameters | Safety |
|---|---|---|
| Hydrocollator pack | Water about 158–167°F (70–75°C); pack on the patient 15–20 minutes | 6–8 dry towel layers is standard teaching. A commercial terry cover usually counts as 2–4 layers—add towels to reach 6–8. Check skin at about 5 minutes. Never lie the athlete on the pack (body weight plus heat). |
| Warm whirlpool | Often about 98–110°F (37–43°C); 10–20 minutes | Do not exceed the upper end. Full-body hot immersion stresses the heart. Open wounds contaminate the tank. |
| Paraffin | About 118–130°F (48–54°C); dip-wrap 6–12 dips, then wrap 15–20 minutes | Hands and feet. No open wounds, rashes, or acute inflammatory joints. |
| Contrast baths | Common teaching: about 3–4 minutes warm : 1 minute cold, 4–5 cycles | End on cold if the goal is edema control; end on heat if the goal is stiffness. Evidence that contrast 'pumps' edema is mixed—treat it as comfort and circulation, not magic. |
Contraindications, skin checks, traps
Do not use cryotherapy over:
- Raynaud disease or phenomenon (exaggerated vasospasm)
- Cold urticaria (wheals, and rarely systemic anaphylaxis)
- Cryoglobulinemia / paroxysmal cold hemoglobinuria (less common, still tested)
- Regenerating peripheral nerve (cold can delay regeneration and injure the axon)
- Open wound (especially ice pack or whirlpool contamination; cooling also slows healing)
- Circulatory compromise / peripheral vascular disease / unrepaired vascular injury
Do not use heat over:
- Acute inflammation or acute injury (you will feed swelling and bleeding)
- Impaired sensation or impaired cognition (the patient cannot report a burn)
- Malignancy in the field (increased local perfusion is the concern)
- Deep-vein thrombosis (DVT) or thrombophlebitis (do not vasodilate over a clot)
- Recent hemorrhage, infection in the field, and (for full-body heat) unstable cardiac status
Skin checks are the intervention. Look at the area before, at about 5 minutes for heat, and whenever the athlete reports odd pain. Document color, wheals, and the athlete's sensory report. A mottled, marble-white, or blistered field means stop.
Exam traps: (1) a hydrocollator pack directly on skin—that is a burn protocol, not a treatment. (2) Ice over a superficial nerve for 40 minutes—the common peroneal nerve at the fibular head and the ulnar nerve at the cubital tunnel have published neuropraxias after prolonged ice. (3) Using a recovery CWI recipe for exertional heat stroke, or claiming ice heals the ligament.
Which statement correctly matches energy-transfer mode to a common athletic-training thermal agent?
A soccer player wants a cold tub after extra time. Separately, a wrestler collapses with suspected exertional heat stroke and a rectal temperature of 41.2°C. Which plan matches evidence-based cooling goals?
Which application is consistent with standard thermal-agent safety teaching?