Early Morning (4am - 8am)
PROs: The sun is down or starting to come up and the world is beginning to wake up and there is a great feeling of serenity when you run before the world begins to rumble. Chances are you will come across other runners out for the same idea and if you time it right, you can start in the dark and finish when the sun is rising and be ready to start the day. Great way to start your metabolism and increased blood flow early.
CONs: Too Early. Haha. Let's get the obvious out of the way: you don't get to sleep in. If it's the weekend, this may be your few days to hit the snooze. If you are starting before the sun comes up, darkness may be a factor. Also, cars leaving for work tend to be driven by half-awake people who haven't had their coffee so be careful.
Late Morning to Early Afternoon (10am - 1 pm)
PROs: You are able to get your run in before the day starts to really get going. If you are running through neighborhoods or parks they will tend to be less impacted with people due to work or school. You are also starting before the heat is at it's peak. At home parents: this may be your time to run while the little ones are at school.
CONs: The sun is out and depending on your area it can get warm early. Sunscreen may be needed along with proper hydration. This also may be inconvenient for those that work a 9-5. There is also the possibility of a lunch crowd the later you start. You could be surrounded by those speeding to run errands or those trying to squeeze in a 40 min run during their lunch break, so keep an eye out in case they don't.
Late afternoon (2pm - 5 pm)
PROs: This may be inconvenient for most people which can be a plus for you. Running areas will be less impacted with those avoiding the middle-of-the-day. You are also getting in some miles to burn off your lunch and activating your metabolism before dinner.
CONs: Heat will be at it's peak during summer and you will need to plan accordingly. Proper skin protection, water/sports drink will be required. Try to map your run to include water fountains or bring a few dollars to replenish your drink supply. This is also extremely inconvenient for 9-5ers during the week.
Evening (6pm - 9pm)
PROs: Depending on your start time a run before dinner is a great way to get your metabolism going pre-meal. The sun and heat should be low offering a more comfortable atmosphere. It's also a great way to bring the end to a day and run when the sky is filled with its' beautiful sunset colors.
CONs: If you have dinner before, running on a full stomach could be problematic. If you have a light dinner to make the run easier, you could be hungry when you return resulting in late-night snacking. The evening energy boost may also prohibit those that hit the sack early from falling asleep right away. Plus all the best television is on. :)
Night (9pm - Midnight)
PROs: This is a great time to run if done properly. It is generally pretty quiet the later you run as long as you are not in a major city running downtown on the weekend. The weather should be agreeable as long as it isn't too cold and foot traffic should be minimal.
CONs: Safety is an issue. It is late at night and the streets should be empty. If something happens such as an injury or you get lost, there may not be as many people around to assist you compared to earlier in the day. You'll also need to plan for no help from the sun and trying to run in well lit areas. Reflective clothing and blinking lights are highly recommended.
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