Great question. The short answer is yes, but there are several important factors you need to consider:
1. What phase of training are you in? If you are base building, you can replace 1 minute of easy running with 2 minutes of sex, as long as your HR exceeds 140. If you are focusing on higher quality training, replace 1 minute of running with 2 minutes of sex, without exceeding 5% of your weekly mileage. When you are tapering, I would encourage as much sex as possible, but only in place of a warmup.
2. What event are you training for? Middle distance runners can replace easy running with sex, but should be careful to ensure that their HR does not exceed 200. 10k-marathon runners can also, but should not exceed 30 minutes of sex on the same day that they are running more than an hour. Ultra marathoners never get laid, so they don't have to worry about it.
3. What is your level of running experience? If you are new to distance running, replacing a few miles with sex can be a great way to add some excitement to your training, but just make sure that you don't replace more than 50% of your miles with sex. If you have 2-5 years of experience, you should be more focused on running, and you really need to focus on running as many miles as possible. Once you have exceeded five years of distance running experience, you will start to see diminishing returns from high mileage, so you might as well replace a few miles with sex.
Hope this helps!