If you are a person who suffers from cramping during or after your training runs, determining your sweat rate could help you a lot. Properly replenishing the water your body loses during your workouts is one of the best ways to combat cramps. Determining your sweat rate can be done in 4 easy steps that I provided below.  

Step 1. Weigh yourself

Weigh yourself before your training activity. Ideally, it's best to weigh yourself nude; certain training clothes retain water and will cause your results to vary. If you are going to drink or consume anything during your training, you should also weigh these items; the information will be necessary for step 3. 

Step 2. Perform your activity. 

You must keep track of how long your training takes during this step. You will use this time in your final calculation.  

Step 3. Weigh yourself after the activity

Make sure you towel off any excess sweat before jumping on the scale. Once you have determined your post-activity weight, you will subtract it from your pre-activity weight to determine your sweat rate. 

Pre-activity weight + Drinks / Consumption items (consumed during workout) - Post-activity = Sweat Rate.

Step 4. Wash, Rinse, Repeat. 

Repeat this activity several times in different conditions to determine an average for best results.