KLK3 and prostate carcinoma: Similarly, recent results from a randomised-controlled trial of 12 weeks high intensity interval training vs. usual care in men undergoing active surveillance for prostate cancer revealed a statistically significant between-group difference in PSA (−1.1 μg/L, P=.04) but the reduction from baseline in the exercise group was within biological variation of PSA (−6.6% ≈ CV 4.8%2) (69).