What is the purpose of an ice bath after running?

The primary purpose of an ice bath is to aid recovery and reduce the level of delayed onset muscle soreness.

The mechanisms include aiding normalisation of body temperature, flushing out muscles due to constriction of blood vessels & compression through hydrostatic temperature, a decrease in metabolic activity, balancing of the sympathetic & parasympathetic systems and a reduction in muscle damage.

Athletes report feeling more energised at the following training session and report reduced muscle soreness enabling them to train more effectively.

Fatigue is reduced and fatigue is the main precursor of injury. Therefore, using an ice bath reduces fatigue and lowers the risk of injury.