Do not stretch before an intense workout. Consensus has changed away from doing so. Instead perform a warm-up prior to beginning your exercise in earnest. Stretching a "cold" muscle could lead to injury itself.

https://www.health.harvard.edu/staying-healthy/ask-the-doctor-stretching-before-exercise

https://www.bu.edu/articles/2015/stretch-before-exercise-not-so-fast/