This paper will consider human thermoregulatory response differences between upper and lower body exercise. In addition, the thermoregulatory problems of spinal cord injured individuals are examined. For able-bodied individuals, the rise in core temperature is independent of the skeletal muscle mass employed and dependent upon the metabolic rate during exercise. The avenues of heat exchange, however, are different for individuals performing upper body as opposed to lower body exercise. During upper body exercise, there is a greater dry heat loss from the torso; however, no additional heat loss (as compared to lower body exercise) occurs from the exercising arms. If an individual performs upper body exercise in cold water, there will be a greater heat loss and susceptibility to hypothermia than during lower body exercise. A spinal cord injury impairs one's ability to thermoregulate because of: (a) loss of autonomic nervous system control for vasomotor and sudomotor responses in the areas of the insensate skin; (b) a reduced thermoregulatory effector response for a given core temperature; and (c) a loss of skeletal muscle pump activity from the paralyzed limbs. As a result, a spinal cord injured person has a reduced ability to tolerate thermal extremes and to perform aerobic exercise. Surprisingly little research, however, has focused on the ability of the disabled to thermoregulate during exercise. Recent data suggest that rectal temperature measurements may underestimate the thermal burden imposed on wheelchair athletes during competition.