Rest is crucial to adaptation and progression - most of us know that. However, the statement leaves a lot of questions unanswered, such as how many days off a week are advised, and what exactly constitutes rest.
The answers come down mostly to individual experience and there will be a lot of variation. However, there are certainly some sensible rules of thumb we can employ.
Why rest anyway?
Training is a process of breaking your body down, and rebuilding it - the new model of yourself being closer and closer to the optimum required for the task at hand.
The rebuilding part of the process doesn't come about until we rest.
"When you've really exerted yourself, you'll have depleted your glycogen stores so a rest day is a great day to top your energy stores back up. That can take 36-48 hours if you've had a really demanding couple of days," explains Matt Rowe, former professional, now part-time racer and founder of Rowe & King coaching.
"Also, your muscle fibres have been damaged and broken down, and [the rest day is] when they knit themselves back together and become stronger."
How often should we rest?
How often a rest day is needed is person specific. However, there are patterns.
"Pro athletes might be able to string five, six, seven days back to back no problem, because a lot of it is generally more steady state. Once within race season, the intensity and travelling causes a lot more fatigue, so they would need a rest day.
"For amateurs, when someone says they want to train as best they can, and can ride seven days a week, I always advise them to take two rest days a week.
"That's partly to manage them physically, but also mentally. Unless you're a professional, the weekends and spare time is valuable for your family and lifestyle. It's easy to over-prioritise cycling when really it is a hobby," he explains.
Those recommended two days don't change with fitness either, or the time of year.
"When you're fitter, you just train more intensely on training days. There's a ceiling to how much you can put yourself through, and my advice has always been to overload more on your training days but stick with those two rest days."
Rowe is adamant that recovery days shouldn't be tainted.
"Some people consider half an hour on the turbo or rollers recovery, I always say a rest day is a rest day - for your body and your mind. I'm not an advocate of active recovery. You're either resting or training. As soon as you start getting your kit on, you're in bike mode."
And it doesn't count if you use it to hike up a mountain, swim the channel or pound the streets in search of an entire new wardrobe.
"Make sure it's high quality rest, and keep hydrated. Be as conscientious as on training days - tell yourself 'my purpose is to rest properly'. You can not ride a bike, but go hiking, walking round town or swimming - that's not rest," says Rowe.
Similarly, if you're a power based athlete or someone who enjoys time in the gym, Rowe says he'd treat a session pumping iron as similar to a high intensity bike session or a heavy chaingang - so the same amount of recovery applies. A gym day definitely doesn't count as a day off.
Double up for extra results
If all of that feels too restrictive, and you've got an appetite for more, then doubling up is an option - with two bike rides a day, or a bike session and time in the gym come the evening.
"Double days are fantastic, because you get two releases of endorphins and testosterone. It means you can get two hits in one day.
"Plus, in the second session, you're training on tired legs - which gives you the cumulative fatigue effect. You rarely get to replicate the demands of the final half hour of a three hour race in training, because you never get the chance to go that hard, for that long, in a day. Double days can help replicate that."
When to take an unscheduled break
Sometimes you might find yourself needing an unplanned Kit-Kat moment in the shape of a rest day that wasn't on the schedule.
Rowe suggests there are two warning signs which shouldn't be ignored.
"If you're going out, and feeling sluggish, and you can't complete the session you want to complete, that's an obvious sign. Listen to your body, the sensations and how you feel. I'd say anybody riding their bike six or seven times a week is probably riding too much.
"The other one is heart rate. You get used to the way your heart rate picks up. If you're struggling to get your heart rate to go up as normal, that's a sure sign that you're fatigued and due a rest day."
"When you go on holiday without a bike, in the first session back your heart rate flies through the roof as soon as you put in an effort because you're super responsive to that intensity. At the other end of the scale, on the last day of a training camp, when you go to do some efforts, you'll struggle to get it up.
"I was speaking to [former pro] Greg Henderson about it, he was saying in the last few days of the Tour de France his max heart rate would be 15 beats less than it was at the start. Because he was just that fatigued. Obviously in the Tour de France, you cant take a rest, but amateurs can."
Exceptions are at two ends of the scale: older riders, and youngsters.
"As riders get older, they do need a little bit more rest. But it is very individual. You get some 55-year-olds who will happily ride five or six times a week, and you might get a 40-year-old who just feels they need that rest. As a general rule of thumb, the need for rest days does slightly increase as you get older."
Parents of young riders should play it by ear, Rowe says, taking special care to ensure that enjoyment of the sport isn't being lost.
"Kids have an ability to absorb varying levels of workload, so it's very individual. As a parent, the main thing you want to watch is their head - their motivation, and enjoyment of the sport. So many kids get to their teenage years and if they're not really in love with the sport, they find an easy exit.
"When they're young, make sure they're happy, if they're bored or tired, tell them to take a day off. With a coach or data, you can more accurately advise. But as a sweeping statement: as long as they're happy you're doing a good job."
Michelle Arthurs-Brennan is Cycling Weekly's Tech Editor, and is responsible for managing the tech news and reviews both on the website and in Cycling Weekly magazine.
A traditional journalist by trade, Arthurs-Brennan began her career working for a local newspaper, before spending a few years at Evans Cycles, then combining writing and her love of bicycles first at Total Women's Cycling and then Cycling Weekly.
When not typing up reviews, news, and interviews Arthurs-Brennan is a road racer who also enjoys track riding and the occasional time trial, though dabbles in off-road riding too (either on a mountain bike, or a 'gravel bike'). She is passionate about supporting grassroots women's racing and founded the women's road race team 190rt.
She rides bikes of all kinds, but favourites include a custom carbon Werking road bike as well as the Specialized Tarmac SL6.
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