Take It Easy - The Importance of Rest Days for Runners
In the words of one of the greatest rockstars of all time - The Boss, Bruce Springsteen - “you can’t start a fire without a spark… and you can’t keep the fire going without rest…” (amended by Madeleine L. Brown)
Contrary to the belief of many starting-out and seasoned runners, rest is the oxygen that allows the fire of performance to breathe. Without oxygen - without rest - it is impossible to give space for the adaptations necessary to fuel forward growth to develop. Without rest, it is more likely that our metabolic, hormonal and musculoskeletal systems become bathed by the stress of running, and that spark that we work so hard to ignite gets smothered.
An iconic moment for rock music and running alike - when both sectors realised that you can’t start a fire without a spark… and you can’t keep the fire going without rest.
Let’s take the Dancing in the Dark metaphor a step too far. Think of your running journey as a literal fire. You begin by collecting little bits of kindling - easy runs, strides, a few tempo sessions here and there - before adding the larger sticks and logs of threshold sessions and long runs. Your love and passion for moving your body is the initial spark. With excitement and passion alone, the kindling may burn for a moment, however, it will eventually become smothered and dwindle away without any time for the larger fuel to catch alight. What is really needed to boost that flame is oxygen. Rest is oxygen in this metaphor - the invisible and often forgotten about step - that allows the body to truly adapt to the stress of running.
Running is a physiologically stressful activity. When we run, stress hormones including cortisol and adrenaline are released. Cortisol and friends are necessary to facilitate many of the physiological processes that make running possible, such as a higher heart rate, more rapid breathing patterns, the use of glucose and stored energy stores as fuel and a sharper, focused mind. Whilst this “stressed state” is necessary for running harder / better / faster / stronger, too much of it can be overwhelming for the body, and tip us over the edge into hormonal imbalance, energy deficiency and fatigue. If not dealt with appropriately, this increasing the risk of injury and less time in the sport.
The fascinating thing about running is that it is not a linear process. In the world of running, one plus one does not necessarily equal two. By the same token, more training does not necessarily equate to more improvements. Training without allowing space for the body to recover, regenerate and re-set is essentially a null and void activity. Constantly adding water to a cup, without tipping out a little bit here and there will only lead to the cup overflowing… the body can only handle so much stress at once. After so long, it will compensate in a negative way to protect itself where necessary.
Symptoms such as extreme exhaustion, low mood, excessively sore muscles, lack of motivation to train and increased relative effort during sessions (i.e. runs feeling “harder” than they should) are all early indicators that more rest may be needed.
Benefits Of Rest Days
Repair of muscles
Relief of tendons and ligaments
Replenishment of energy stores
Rests and refreshes the mind
Overall reduction in injury risk (both soft tissue and bony injuries)
Muscle Repair
Running causes small tears within muscle fibres called micro tears. Unlike pathological muscle tears (e.g. over-use injuries or traumatic tears), micro tears are not only not detrimental to development, but essential. Micro tears help to facilitate the adaptations required for muscles to grow and develop in response to the stimulus of running. In the first 0-24 hours after a run, blood flow to damaged muscles not only helps to remove waste products such as lactic acid, but also facilitates the delivery of oxygen, amino acids and vitamins / minerals essential for the repair of damaged fibres. Under the right conditions, muscle fibres will not only repair, but grow and adapt to make running a more efficient activity. This can take anywhere between 48 to 72 hours depending on how strenuous the previous workout was. Additional factors such as overall life stress (e.g. work, children, relationships, family dynamics), sleep, nutrition / hydration and hormonal factors can also feed into recovery from running, so it is important to consider what else is going on in your life at a particular time, and factor this into whether more rest may be required. Inadequate rest and time between strenuous sessions may cause the balance between muscle damage and repair to skew more towards breakdown. This is when muscle soreness and fatigue can set in, which, if not acted upon, may lead to injury.
Tendon and Ligament Relief
Muscles are connected to bones via tendons. Bones are connected to bones via ligaments. Tendons and ligaments, whilst still considered part of the “soft tissue” component of the musculoskeletal system differ slightly to muscles not only in their structure, but also their function. Structurally, these tissues are more robust than muscles. The fibres that make up the “band-like” tissue contain more collagen protein, and are also arranged in lines adjacent to each other. This allows both tendons and ligaments to withstand greater forces compared to muscles along, hence, they absorb a lot of the mechanical stress of running. Unfortunately, the blood supply to both tendons and ligaments is less than that of skeletal muscles. This means that their healing tendency is typically slower. Tendons and ligaments take up to 2-3 times longer than muscles to recover from a strenuous activity. Adaptation is also slower.
Replenishment of Energy Stores
One of the most important - but less recognised - reasons for rest days is that these days of less activity allow the body a chance to recovery energy stores. During exercise, the body preferences the use of glucose (sugar) as an energy source. When free glucose is not available, the metabolic system taps into stored glucose stores within the liver and muscles to fuel activity. These glucose stores are called glycogen, and are essential for facilitating aerobic activity. Inadequate glycogen stores have been linked with impaired performance and increased injury risk. Replenishing glycogen stores depends on consuming high-quality carbohydrates in the hours and days immediately post a workout. For a variety of reasons - both intentional (e.g. disordered or restricted eating, diet plans) or unintentional (e.g. busy work schedules, early training days) it is relatively common for runners to under-fuel on training days. Rest days allow for ongoing carbohydrate intake without the associated use of glycogen that happens on run-days, thus allowing for the replenishment of energy stores required to keep running and adapting in the right direction.
Refreshment of the Mind
Running goes against almost everything that humans have evolved to do - rest, relax and indulge in the pleasure of not having to hunt for food, safety or warmth. Revolting against evolution is hard, but that is also where most of the fun lies! Regardless, it can strain the brain. Rest days are essential to re-set the mind and keep the excitement and desire to run alive.
How Much Rest Is Enough?
As with most things in life, there is no single answer to the ideal number of rest days to minimise fatigue, injury risk and overtraining, whilst yielding the benefits of consistent run training. For athletes new to running, 2-3 total rest days per week is regularly quoted as appropriate. This leads to approximately every second day being a “run” day, with other days being either a total rest day or a day of low-impact / cross-training. As running becomes a more frequent and familiar activity, it is appropriate to start reducing the number of rest days per week. 1-2 total rest days (with one day of complete rest and one day of low-impact / cross training) is appropriate for most runners with a decent amount of experience behind them, but not yet elite. Elite and professional athletes can generally get away with one rest day per 7-10 days.
Rest Day Priorities
Sleep - sleep in, nap in the afternoon, go to bed early
Refuel - enjoy foods that make you feel good… do NOT eat less, just because it’s a rest day
Gentle movement - swimming, walking or yoga can all help promote blood flow without the stress on ligaments, tendons and bones
Manual therapy - massage, thera-gun, foam rolling not only feel good, but also may help improve blood flow and subsequent recovery
Read a book, watch a film, spend time with family and friends… do things other than running / thinking about running
TLDR
Running is a stressful activity. It causes small tears to muscles, tendons and ligaments that need to be repaired.
The repair of micro-tears is actually what facilitates growth and adaptation of muscles. The inflammatory response post-exercise causes increased blood flow to the damaged areas, delivering oxygen and nutrients to facilitate repair, and removing waste products such as lactic acid.
Too little time between runs means that there will be inadequate time for healing to take place. Inadequate recovery = ongoing damage to muscles = increased fatigue, soreness and injury risk.
Rest also allows time for energy stores, particularly glycogen within the liver and muscles, to be replenished. This is important to allow ongoing hard efforts to occur.
New runners should take anywhere between 2-4 days off running per week. More advanced runners may be able to recover with just 1-2 non-running days per week.
Symptoms that suggest more rest may be needed include prolonged muscle soreness, fatigue, low mood or motivation to run, disturbed sleep and efforts feeling harder than expected.
Inadequate rest may contribute to Relative Energy Deficiency in Sport (RED-S) which can have life-long implications for both female and male athletes.