Figure 2
Relative pattern of temperature change in different tissue layers during exercise, cooling and post-cooling period. Data are averaged from studies measuring changes in tissue temperatures using various forms of cryotherapy [4, 9, 43, 45–48, 54, 55]. Skin temperature (green, Tsk) increases during exercise, decreases exponentially through cryotherapy, reaching nadir earliest, and increases exponentially through post-cooling period. Core temperature (blue dashed, Tc-general) changes induced by cryotherapy applied to large mass increases during exercise, and decreases during cryotherapy (rate dependent on thermal gradient and peripheral blood flow). Core temperature cools slower than other tissues and does not begin to return to baseline until 1 h post-cooling. Core temperature (blue solid, Tc-local) changes induced by cryotherapy applied to a small mass is minor during cryotherapy and modest throughout post-cooling period as blood cooled at periphery is returned to core. Superficial intramuscular temperature (red, Tm@1) increases during exercise, declines linearly during cryotherapy, and increases linearly to baseline within 1 h. Deeper intramuscular temperature (yellow, Tm@3) increases during exercise decreases linearly during cryotherapy at a lower rate than Tm@1, continues to cool through the post-cooling phase as heat is transferred to warmer superficial tissues, returning to baseline later than 1 h.