Masturbate right before gym, then go train. Note how your performance was. Especially if its a squat or a deadlift day.
Note down what time you went to sleep, when you woke up, and every meal you ate (all calories, including macros).
Now refrain from masturbation from that day until the next session you have of the same exercise, make sure you go to sleep within the same time the night before, wake the same time the day of training, and eat the same exact meals, go train the same exact exercise, same sets, reps, and weight. Note your performance.