THE RUBBER BAND MAN
Bands certainly have a place in resistance training. When they became popular, a lot of "hardcore" lifters poo-poo'd the idea that these could be effective in the land of iron (including myself). While I believe it is ideal to have access to a variety of equipment (including free weights), resistance bands certainly have earned their spot as an effective training tool in this arsenal.
One common question I get from those who use bands is "how do I calculate and track the resistance in my training log?" While it's easy to tell which band has more tension, quantifying it can be tough. Below are some steps that can help make this easier and measurable.
First, assign a number to each band based on tension. Sometimes the manufacturer will give you max resistance per band. Certainly there is going to be variability on this but it will give you a guideline. For example, yellow band is 20, red band is 40 and black band is 60. Make it easy to remember and use a sharpie to write it on the band.
Next, when you are logging an exercise using a banded movement, input that number you assigned the color. So if you use a red band for pull aparts and you get 15 reps, you would log it at 15x40. In the event you double up on bands, simply add the two numbers together.
While this method isn't exact (band tension will vary), it will allow you to achieve the main goal of training: progressive resistance. Another pro tip, keep an eye out for frayed or cracked bands, no one likes a broken band-snap to the face (speaking from experience here too!)