Rest and recovery days are important for both your athletic performance and your fitness progression for a variety of reasons. Let’s break it down and find out what exactly goes on when you give your body the correct amount of rest.
4. Bone Recovery
Consistent physical activity can modify connective tissue (cartilaginous, fatty, and elastic tissues) which will allow your body to make significant bone remodeling and increase bone density. This is the reason why one of the best methods to maintain current bone mineral density is through physical activity.
Physical activity increases the physical stresses on bone, and when the stressful stimulus is complete (and the bones are allowed to recover) all of that bone flexing stress that you engaged in can help activate cells called osteoblasts, which help the bone stay strong and resilient.
But the opposite is also true. Repetitive bone stress without adequate recovery can result in bone breakdown and loss of bone density. Repetitive stress without recovery can also deplete the body of essential bone-building minerals and vitamins—although this would be an extreme circumstance.
5. Metabolic Recovery
A study at McMaster University divided well-conditioned runners, averaging about 50 miles of running per week into three groups and had all the runners go into some version of a recovery mode. During this recovery mode, one group simply relaxed for a week, the second group ran easy for 18 miles over the course of the week, and the third group ran a measly six miles during the week that consisted of all-out 500-meter intervals on a track. So their workouts were quick and dirty, just like me.
After this recovery week was over, all three groups performed a treadmill “run to fatigue” test, some blood tests, and a muscle biopsy. The results went like this: the “did nothing for a week” group improved by three percent, the runners who logged 18 easy jogging miles improved their performances by six percent, and the runners who ran the six miles of 500-meter intervals saw performance increases of 22 percent.
This tells us that recovery is important but that you don’t have to hit the couch with a box of bonbons to get the full benefits.
So, what went on metabolically that caused these changes? The researchers found that the low-volume but high-intensity runners had:
More glycogen (storage carbohydrate) in their leg muscles
More aerobic, oxidative enzymes in their legs
Higher red blood cell density
Higher blood plasma
So this may seem confusing at first, but if we look closely, we see that all three of the groups improved during this recovery week but the biggest gains happened in the group that had plenty of rest with just a few fun bursts of exercise during the week. This tells us that rest and recovery is important but that you also don’t have to hit the couch with a box of bonbons to get the full or even the best benefits.
6. Nerve Recovery
What we refer to as the central nervous system (CNS) includes your brain and spinal cord as well as the part which connects to your muscles via a thing called the peripheral nervous system.
This is how it works: When you want a muscle to contract (on purpose or as part of an automatic cascade of movement), a message travels from the brain and spinal cord and eventually arrives at the individual muscle motor units through something called a neuromuscular junction. This is where the muscle receives the message and gets activated.
In the same way that the muscle itself can fatigue (and get torn and injured) the training can also damage your nervous system. Sports scientists call this neural fatigue, and it can really drain your central nervous system, as well as the local nerves in the muscle sites themselves.
This fatigue happens when your body releases things called inflammatory cytokines (tiny chemical messengers) in response to the muscle damage that is brought on by your training. These cytokines attach themselves to the receptors in your central nervous system and in an oversimplified way, block your neural recovery.
Unlike muscle damage, and this is very important to keep in mind, nerve fatigue doesn’t just come from training. It can come from other nervous system stressors like lack of sleep, pharmaceuticals, caffeine, alcohol, or other day-to-day stresses. Because your nervous system is the machine that makes all of your muscles fire, if your nervous system is under-recovered, then not only the strength but also the basic functioning of your muscles is messed up. This is why you can still get overtrained, or be in a state of under-recovery, even if you’re not exercising excessively, but perhaps partying, working long hours, or sleeping poorly.
If your nervous system is pooped out, it is pooped out.
It is important to remember that your central nervous system doesn’t differentiate between your muscle groups. If your nervous system is pooped out, it is pooped out. So let’s say that you do a hard bike ride today, and then head to the gym tomorrow to lift some heavy stuff, even though you mostly worked your legs on the bike ride you may still find that your strength doing an overhead press is wimpier than usual. That is nervous system fatigue.
Alright! There we have it. This was by no means a comprehensive recap of what I learned during my coach certification classes but hopefully I outlined enough of the benefits (and detriments) of recovery that you will reconsider ignoring your next rest day to instead squeeze in “just one more workout.”
When you’re under-recovered, your ability to positively adapt to your training is zapped, and—in addition to putting yourself at risk of illness and injury—you really are wasting your precious training time. I don’t know about you, but I want results when I train.