The science of rest, according to Daniel Chapelle, exercise physiologist at Virgin Active.
There are both physical and mental signs that indicate you need a rest day. First, there are the objective measures – things like reductions in sleep quality and duration, or drops in physical performance. You should also be looking out for an increase in the frequency of injuries & the occurrence of sickness.
On the mental side, things are a little bit more subjective and can be classified as your ‘biofeedback markers.’ This includes your motivation, energy, stress levels, hunger, and mood. When I’m working with my clients, I get them to rate those categories from 1–5 at the end of each week. You’ll start to see patterns and correlations emerging between these factors – things like reduction in motivation, low energy and poor mood coinciding with an increase in stress and hunger.
Exercise is an acute stressor; it increases the demand on a number of our body’s mechanisms – including our neurological, muscular, cardiovascular, and endocrine systems. When we take a rest day following periods of exercise, we’re allowing our body to adapt to the stress and replenish those systems. Following high-intensity interval training this can include the repair of tissue such as muscle, tendon and bone, as well as the replenishment of stored glycogen. Additionally, our bodies flush out exercise induced by-products – like hydrogen, lactate, and CO2.
It’s important to pay attention to what else is happening in your life. I think of energy as being contained in a bucket, and you can only dedicate so much of it to so many things before you run out. If you’re experiencing high stressors in your work life and/or home life, and you’re doing six HIIT sessions a week, well, something has to give. At that stage, it’s likely to be complete burnout, sickness, or injury.
I’d recommend having a plan for the week that not only accounts for rest, but that has strategies around what you can actually do on those days, as well. If you’re a naturally fidgety person, you could fill that time with a restorative walk in nature or try a light yoga session.
However, it’s also essential to take at least one day to do nothing – use that time for friends and family; it will help you to regain that work/life balance.