Adaptations to Post-exercise Cooling: Context Matters!

Historically cold application (cryotherapy) was used in the treatment of soft tissue injury, however more recently its popularity stems from an ability to reduce perceptions of delayed onset muscle soreness (DOMS) often associated with intense exercise, with the added potential to induce acute subsequent performance benefits. Whilst the acute recovery period is vital for restoration of energy stores and recovery from exercise induced damage, it is also an important window for mediating adaptation to the exercise stimulus via cell signalling and remodelling. In the last decade, many labs have been able to show post-exercise cooling can enhance the gene expression of the so called “master regulator” of mitochondrial biogenesis, PGC- 1α, above the exercise response. In doing so it could be suggested this might lead to enhanced endurance adaptations via improved mitochondrial biogenesis. Indeed, regular cooling following training sessions has been shown to enhance PGC-1α protein content, some markers of cellular stress response and signaling molecules related to mitochondria biogenesis. However, research seems to show a paradoxical response between adaptation towards a more endurance or resistance phenotype. Acute post-exercise cold water immersion is suggested to dampen gene transcription associated with ribosome biogenesis whilst attenuating acute changes in satellite cell numbers and activity of kinases that regulate muscle hypertrophy. Interestingly, this is associated with further implications when postexercise CWI is regularly used, such as dampened gains in muscle mass and strength following 12 weeks of strength training and myofibrillar protein synthesis. Therefore, the aim of this mini review is to critically discuss the contrasting research and provide some context for the use of these methods moving forwards.