Why rest days are important
When you're really 'on a roll' in the gym and find yourself smashing PRs left, right and centre, the last thing you might want to do is take a rest day - or even worse - take a week or more off training.
As tempting as it may be to go all-out, rest isn't just an optional treat for the weak-hearted and un-dedicated. It's an essential part of your training, and if you neglect it, you'll pay the toll sooner or later. So why in particular when it comes to reaching your goals are rest days important? Here's why...
Rest days are important because they prevent injury and CNS fatigue
Every time you hit the gym for an intense workout -- whether it's a HIIT session on the treadmill or a powerlifting routine in the weights area -- you will be creating microscopic tears in your muscles. This essentially enables you're body to adapt and become more stronger and more resilient to training stimlulus. As a rule, small microscopic tears isn't a problem. It's actually the whole point of working out. But when you overdo your training or cut back on your much-needed rest, those intentional "micro-injuries" can easily become real injuries that prevent you from training indefinitely, or worse.
This damage isn't just limited to an increased risk of spraining your ankle, tearing a tendon, or suffering a rotator cuff impingement, either. There's an actual condition known as Overtraining Syndrome (OTS) which refers primarily to the stress done to your body's central nervous system by training too hard without sufficient rest.[1]
If OTS gets too severe, not only will your strength and conditioning gains wither away to nothing, but your immune system will suffer, your mood will plummet, and your body will let you know, loudly and in a variety of ways, that something's wrong. Instead of taking a rest day, you may find that you have to skip the gym for weeks, if not months, dependent on how severely you've over-trained.
To avoid this situation and to get the most out of the time you put in the gym, make sure that you get enough rest to allow your body to catch up and strengthen. It's a proven way of reducing your injury risk.[2]
Rest days are important because they boost morale and keep you moving forward
One of the most important parts of any fitness routine -- and one of the most often overlooked -- is consistency. It's all well and good to hit the gym like a wild animal fighting for its life, but that intensity won't be worth anything unless you're able to maintain it over a significant period of time.
Progress in the fitness world is made by moving in the right direction in a controlled way, one step at a time. Not by going wild for a little while, then burning out and taking a month off training, particularly if you're looking to have fitness as part of your lifestyle.
One of the easiest ways to go off the rails in your training is to lose morale and end up giving in to feelings of irritation, hopelessness, and despondence. And one of the easiest ways to end up there is by overtraining to the point where you dread and despise each workout, all while not giving yourself enough time to recover. This is a mistake, more often beginners make.
If you overtrain to the point of breakdown, not only will you be physically unable to train for a while, but your mood and motivation will take a serious battering, too. Whilst it's great to be keen on going to the gym, sometimes, your eagerness may not end up in your favour, when it comes to training.
If you're new to the gym, we suggest to ease your way in by going 2 or 3 times a week, and gradually building this up, so your body can get acclimated to training.
Rest days are important because muscle is built while resting, not while training
It's an old axiom of strength training that muscle isn't built in the gym but the kitchen and bedroom. You might also have heard something weird-sounding like "lifting weights is only 20% of building muscle".
There's a reason why these statements are floating around the fitness world. Weight training is just the beginning of the muscle-building process. Whilst it may seem counterproductive not to be working your muscles for them to grow, rest is the stage in the cycle where you break down your muscle tissue so that it can adapt to the newly introduced strain and grow back stronger.
For it to actually do the "growing stronger" part, it needs to be allowed sufficient rest and nutrition for the recovery to take place.
Interestingly, a major part of this recovery and growth happens during sleep, as confirmed by studies which have shown growth hormone to spike dramatically during deep sleep.[3]
Depending on what muscles you've worked previously, we suggest if you want to workout the next day, try working on a different muscle group for your next workout so that you are giving the muscles you had previously worked enough time to rest. If you're the type of person who likes to go "all or nothing", remind yourself that rest days are just as important as your training days if you want to see optimal results.
When should you take a break from training?
How much rest you need is largely dependent on the individual but you can go by how you feel at any given time.
A generally accepted rule of thumb is that you should take a rest day after each day of intense training, with plenty of sleep, to ensure that you avoid accidentally overtraining.
This is often the way things are done with full-body powerlifting style workouts, where three training days a week, with a rest day between each, is a common formula.
For more bodybuilding-oriented "split" workouts which target one body part a day, it's common to train up to five days in a row, as long as each body part is only worked once or twice per week. Weekends would be taken as rest days to allow your central nervous system (CNS) to recover.
In the event of CNS overtraining, or a strength plateau you just can't seem to overcome, allow your body a week or two off training to recover before diving back in. Similarly, if you've been training hard and consistently for a long period of time, sometimes a week long break from the gym could be beneficial. If you find yourself constantly dealing with post workout fatigue, it's time to factor in an extra few days rest.
In the event of an injury, you're just going to have to avoid straining the wounded limb until it's fully recovered -- whether that takes weeks or months. Likewise, if you've found yourself with a sneaky hangover, you may want to consider giving yourself a day to rest and recover.
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3435910/
[2] http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0838.2010.01152.x/abstract