Runners and Blankets: Thermoregulation, Performance, and Recovery Strategies

Why do runners use blankets?

Runners use blankets primarily for thermoregulation, either to prevent a rapid drop in core body temperature after intense exertion, particularly in cooler conditions, or to maintain muscle warmth and flexibility before a race, which is crucial for performance, recovery, and overall health.

The Post-Race Chill: Why Body Temperature Drops So Rapidly

During a run, especially a long or intense one, a runner's core body temperature significantly increases due to metabolic heat production. The body responds by increasing blood flow to the skin (vasodilation) and initiating sweating to dissipate this heat. However, once the exercise ceases, several physiological changes occur rapidly, leading to a quick drop in body temperature:

• Abrupt Decrease in Metabolic Heat Production: The muscles stop generating the large amounts of heat they did during activity.
• Continued Heat Loss: Evaporative cooling from sweat on the skin and clothing persists. The body continues to lose heat through radiation and convection, especially if exposed to cold air or wind.
• Blood Redistribution: Blood flow begins to return from the periphery (skin) to the core, which, while beneficial for overall circulation, can initially feel like a chill as warm blood leaves the skin surface.
• Glycogen Depletion: After long runs, glycogen stores are often depleted. Glycogen is a primary fuel source, and its metabolism generates heat. With less available, the body's capacity for internal heat generation is reduced.
• Risk of Hypothermia: In cold, wet, or windy conditions, this rapid temperature drop can quickly lead to hypothermia, a dangerously low body temperature, which can impair cognitive function, muscle coordination, and vital organ function.

Blankets, particularly after a race, act as an insulating barrier, trapping a layer of warm air close to the body and preventing further heat loss, thereby aiding in the recovery of a stable core temperature.

Maintaining Pre-Race Warmth and Performance

Runners also utilize blankets before a race, especially when waiting at the start line in cold weather. This practice serves several important functions:

• Optimal Muscle Temperature: Warm muscles are more elastic, pliable, and efficient. They contract and relax more effectively, reducing the risk of strains or tears. Maintaining warmth ensures muscles are ready for peak performance from the start.
• Energy Conservation: When cold, the body expends energy through shivering to generate heat. Using a blanket prevents this unnecessary energy expenditure, preserving vital glycogen stores for the race itself.
• Psychological Comfort: Staying warm helps reduce stress and discomfort, allowing the runner to maintain focus and mental readiness for the upcoming challenge.
• Preventing Stiffening: Prolonged exposure to cold can cause muscles and joints to stiffen, hindering range of motion and potentially impacting running mechanics.

Types of Blankets and Their Specific Uses

The type of blanket a runner uses often depends on the specific situation and environmental conditions:

• Mylar (Space) Blankets:

  • Mechanism: These thin, lightweight sheets are made of reflective material. They work primarily by reflecting the body's radiant heat back towards the runner, significantly reducing heat loss through radiation.
  • Advantages: Extremely lightweight, compact, waterproof, inexpensive, and highly effective for emergency use or immediate post-race warmth.
  • Common Use: Universally provided at the finish lines of major races to prevent post-exertion hypothermia.

• Wool or Fleece Blankets:

  • Mechanism: These materials excel at trapping air within their fibers, creating an insulating layer that slows heat transfer from the body to the colder environment.
  • Advantages: Provide excellent insulation, are breathable, comfortable, and effective in dry, cold conditions.
  • Common Use: Often brought by runners to wear before a race, or for general comfort and warmth during recovery.

Beyond Thermoregulation: Other Benefits

While thermoregulation is the primary reason, blankets offer additional benefits:

• Injury Prevention: Keeping muscles warm before and immediately after exercise helps maintain their flexibility and reduces the likelihood of muscle pulls or strains.
• Enhanced Recovery: Comfort and warmth contribute to a more relaxed state, which can aid in the initial stages of physiological and psychological recovery.
• Psychological Comfort: The simple act of wrapping oneself in a blanket can provide a sense of security and well-being, especially after a grueling effort.
• Emergency Situations: In cases of shock or actual hypothermia, blankets are a crucial first-aid tool to stabilize body temperature.

Practical Advice for Runners

Understanding why blankets are used empowers runners to make informed decisions about their own race day and recovery strategies:

• Assess Conditions: Always consider the ambient temperature, wind chill, and expected duration of exposure when deciding if and what type of blanket to use.
• Layering is Key: Blankets are often part of a broader layering strategy. Wearing appropriate base layers, mid-layers, and outer shells, in addition to using a blanket, provides comprehensive protection.
• Post-Race Strategy: Have dry, warm clothing readily available to change into after the race, even if you're using a blanket. Damp clothes accelerate heat loss.
• Pre-Race Strategy: If using a blanket pre-race, plan to shed it (or an old, disposable one) just before the start to avoid overheating during the run.

The Scientific Basis

The practice of using blankets is firmly rooted in the principles of exercise physiology and thermoregulation. The body's intricate system for maintaining a stable internal temperature (homeostasis) is challenged during and after intense physical activity. Blankets provide an external aid to this system, mitigating heat loss through the primary mechanisms of conduction (direct contact with colder air), convection (heat transfer by moving air), and radiation (infrared energy emitted by the body). By reducing these avenues of heat loss, blankets help runners maintain optimal body temperature, ensuring safety, enhancing performance, and promoting efficient recovery.