When it comes to routine questions on training, one of the most common one is,
"When is the best time to work out in a day?"
The common wisdom is simply working out whenever you can as long as you adhere to the schedule. If there was a time-of-day planning, in the hierarchy of importance, adherence lays the foundation. This is because you need to stick to a particular time to reap maximum results. Following immediately is choosing when you personally feel that your workout would be the most effective, be it morning, noon, or night. No point in scheduling workouts at a time you know your performance won't be optimal.
One notion is to base our workout scheduling based on circadian core body temperature cycles. Based on the data, you should train when your body is the warmest, roughly between 4 pm-7 pm.
This means, to achieve the greatest performance improvements, it's best to always schedule your workouts around the same time of the day, allowing your body to specifically adapt to and prepare the body for training at that time. This is imperative for competitive athletes. They probably want to train around the same time of the day as their typical events. The consensus among research done shows that training at the same time of the day helps perform at peak.
A 2009 study shows a slight trend towards favoring training in the evening when looking at muscle growth in the quads. This went against the belief at that time when it was considered morning workouts were superior because of high testosterone levels. Apparently, acute spiking of testosterone levels in the morning doesn't tell the full story. Comparatively, it was only a 0.8% difference between the morning and evening group spanning 10 weeks, resulting in no statistical significance. Another research conducted in 2016 shed some new light on this topic. There was no major difference in muscle growth between the morning and evening group after 12 weeks. But this study continued the research for an additional 12 weeks. And in the second set of 12 weeks, there was a significant difference in the muscle growth, with the evening group achieving twice as much muscle growth as the morning group.
Points to Remember
Nothing's more important than finding a time in your schedule to fit training sessions you can stick to.
Next is choosing a time to perform your best mentally and physically to get quality sessions done. This is based entirely on personal preference.
If possible, try to fit in your sessions in the evening as your body temperature is optimal at that time. If not, have a good warmup and a dynamic stretching session before working out in the morning to get you all ready for an intense work out.
Try to set each of the training sessions around the same time of day. As you know now, your body can benefit to time specific training adaptations.
And finally, if your ultimate goal is to gain some muscle mass, try to make your specific training sessions in the evening to have a slight edge.
At the end of the day, it's not necessary to get all the five steps done. Simply going to the gym and working out your best is enough for most of us. But, for athletes, bodybuilders, or someone who is a meticulous programmer who wants to squeeze every possible "gain" you can muster, then give all these steps a shot and see your physique changing for the good.