Environmental Impact on Physical Activity 

Cold Weather


Activity in Cold Environments

· Being in the cold may result in a rapid drop in core muscle temperature, affecting the quality of performance. Lower muscle temperature diminishes dynamic physical performance such as muscle strength and peak power.

· Exercises in cold air for long periods of time are likely to decrease cardiorespiratory endurance as the body cools. This is caused by:

Decrease in maximal heart rate, due to the fact that stroke volume stays the same, cardiac  

output falls, and the ability to sustain a high intensity activity. Less oxygen is delivered to the muscles when blood temperature is decreased below 98.6°F. Lactate levels increase as a result of a higher dependence on the anaerobic system due to lower oxygen delivery (Grayson, 2013).


Local cold injuries can arise involving both freezing and non-freezing conditions:

· Hypothermia (most common):  the fall in core body temperature below 95°F, which include signs of shivering, fatigue, loss of strength, and loss of consciousness

· Cold Dry Injuries: involve the destruction of cells from freezing to crystallization

o   Frost Nip – freezing of superficial skin tissue as a result of touching cold metal or exposure to severe wind chill

o   Frostbite [aka. Chilblains] – caused by continuous freezing of cells, which lead to crystallization of fluid, piercing cell membranes and result in tissue death

Hot Weather

Activity in Hot Environment: 

· Studies show that after a core temperature of 100.4°F, the brain and body begin to show a decline in motor and cognitive function. This leads to a deterioration in the ability to complete simple tasks, which in turn, increases the risk for injury due to improper techniques and careless behavior.

Heat Illnesses: 

· Heat Cramps: painful spasms of skeletal muscle, usually occurs in those with sodium imbalance, poor acclimatization, or in individuals that use diuretics. Cramping can be severe and a warning sign to heat exhaustion.

o   Treatment – stop exercise, replace the electrolytes and fluid lost, static stretching, direct compression, ice massage

· Heat Exhaustion: most common form of heat illness characterized profuse sweating, headache, weakness, chills, goosebumps, hypotension, and irritability. Most are unable to continue exercise due to lack of cardiovascular response to the workload, coupled with high external temperatures and dehydration.

o   Treatment – remove from play, cool until temp is <101°F, supine with feet elevated, rehydration

· Heat Stroke:  the most serious of the heat illness syndromes and defined by elevated body temperature that causes damage to body tissue, and ultimately organ failure. Identified by sudden collapse with CNS dysfunction, lack of sweating, loss of coordination, etc.

o   Treatment – lower body temp and contact EMS

· Heat Syncope: involves the loss of consciousness with prolonged standing or due to rising suddenly from a seated position in the heat.

o   Treatment – lie patient in a cool environment, replace fluids

· Heat Edema: mildest form of heat illness characterized by swelling of the extremities due to water retention in the limbs and the inability of the body to excrete salt. Most common during heat waves, or in individuals with poor acclimatization.

o   Treatment – Immediate treatment involves bringing the patient into a cool place, providing cold fluids to drink, and elevating the swollen extremities to reduce swelling (Intermountain Healthcare, 2014).

Prevention/Enhance Performance in Hot Climates

·  Stay hydrated – while many of us can stay hydrated, we neglect our basic electrolyte needs. These help keep our body functioning during the toughest of exercises

·   Time of day – take that run early in the morning, or late at night. Beating the heat is as simple as running at a different time

·  Run with a buddy – a running partner can keep you grounded, help you focus, and stay on pace. This can help especially during hot weather (Fitzgerald, 2014).