Does an ice bath work as well for women as it does for men?
An ice bath cools men and women equally quickly in cases of heat stroke, but whether the effect on muscle recovery is equally large has never been properly compared. Thermoregulation does differ by sex, so advice developed for men cannot simply be carried over to women.
When treating exertional heat stroke, an ice bath cools men and women at the same rate: 0.21 degrees per minute in men and 0.19 in women. Body size and weight made no difference either. A separate protocol for women is therefore not needed for this medical emergency.
For muscle recovery after strenuous exercise, there is a genuine gap in the evidence. Research shows that cold-water immersion improves recovery, but whether that effect is equally large in women as in men has not been investigated. You cannot therefore assume that the findings apply one-to-one to women.
Thermoregulation does differ between the sexes. At rest and during light exercise in cold water, core temperature actually dropped more in women than in men with a comparable body-fat percentage. During intense exercise the reverse was true: women maintained a higher core temperature. Which direction the effect goes therefore depends strongly on how intensely you have exercised before getting into the bath.
A physiological argument even suggests that women may benefit more from post-exercise cooling: they naturally release less heat through perspiration than men, meaning core temperature falls more slowly after hard training. An ice bath could compensate for that difference. This remains a theoretical line of reasoning, however, and has not yet been tested in a direct comparative study.
The cardiovascular response to cold is smaller in women: in a cold-pressure test, blood pressure rose approximately 51% less in women than in men. What this means precisely for the recovery effect of an ice bath after exercise is still unclear, but it shows that a woman's body responds to cold differently from a man's.
This answer rests on one review study of muscle recovery that does not distinguish by sex, an observational study of exertional heat stroke in athletes, two smaller studies on thermoregulation and cardiovascular responses in cold water, a theoretically oriented review article on female athletes, and a smaller study in MS patients. Direct comparative studies on the recovery effect of ice baths specifically in women versus men are lacking. The researchers involved in the relevant studies identify this as an important gap in the evidence.