When it comes to running, not all surfaces are created equal.
It goes without saying that running is one of the most effective forms of cardio out there. Running is a weight bearing exercise, which means that it both burns fat, and builds muscle effectively. Many people (myself included) consider running to be a good way to think, reflect, and stretch your mind. If you are running outdoors, it can also be really gratifying, and a great way to explore new environments.
Running on a treadmill is a little different, however. Treadmills are super convenient as long as you have the space for them. They make it much easier to get exercise during the winter months, and they are easier on your joints than gravel or cement. Nowadays there are tons of programs you can run to, and virtual ways of enjoying the act of running on a treadmill. However, there are pros and cons to anything, and treadmills are no different.
-Easier on your joints
-Readily available despite inclement weather
-Great for rehab, or diving back into running after an injury
-Simulated programs and environments make it fun and competitive
-Easy to track your progress and set milestones
-Lack of agility
-Less muscular engagement than outdoor surfaces
-Easier than running outdoors (this could also be a pro, haha)
-Risk of boredom
-Risk of injury
So there you have it. Regardless of what cardio type you choose, a treadmill is a great thing to have in your workout arsenal, especially for rainy days. Combining outdoor running and a treadmill now and again can help you create a balanced exercise regimen.