Can cold showers make your cells healthier?

Muscles recover and grow after exercise partly through stem cells that clear away damaged tissue and create new muscle tissue. Cold immersion inhibits exactly that activation: the number of active muscle stem cells was significantly lower after cold immersion than after simple light movement as recovery, and the proteins that drive muscle growth were also less active. Over seven weeks of strength training, the type II muscle fibres (the power fibres) in the cold group grew by an average of nearly 2,000 square micrometres less than in the control group. That is a measurable, likely causal effect.

A commonly heard argument for cold showers is that they dampen inflammation in muscles, and that this protects cells. But directly measured muscle tissue showed no difference between cold immersion and simply cycling at low intensity after training: inflammatory cells, stress proteins and growth factors did not differ. The supposed anti-inflammatory effect at the cellular level has therefore not been confirmed.

After five weeks of interval training combined with cold immersion, there were also no benefits for the energy factories in muscle cells (mitochondria), oxygen uptake or running performance. In short: cold showers or immersion do not help cells recover or improve any more than ordinary rest does, and in the case of strength training, cold even impairs growth.

A separate safety point: cold that brings body temperature below 35 degrees (hypothermia) actually causes serious damage to cells and organs, with a risk of heart arrhythmias, loss of consciousness and even cardiac arrest. The mortality rate from hypothermia is twice as high as from overheating. A cold shower at home does not normally bring healthy people into this range, but this is the reason why extreme cold practices carry risks.