After you finish a run, white blood cells rush biochemicals to your legs, where they rebuild your exhausted muscles. This process can last from a few hours to a few days, depending on the damage incurred. During this time, you may feel fatigued, achy and sore: that’s your nerves sending pain signals to your brain to let you know your muscles need a break. You may also notice slight swelling, because fluids carrying healing nutrients can expand tissue. All of this is a healthy physical response known as inflammation. Or, more precisely, acute inflammation, which is the immediate and short-lived reaction to a distinct event.
If you take it easy and fuel properly during this crucial period of repair, your body will return to normal. Better than normal, actually. Your muscles will adapt to the stress so they become stronger.
But if you disrupt this healing process on a regular basis – for example, you skip rest days and do back-to-back hard sessions – you could put your body in a state of chronic inflammation, says Dr Inigo San Millan, assistant professor of physical medicine and rehabilitation at the University of Colorado School of Medicine, US. And that’s not where you want to be.
Chronic inflammation occurs when the body is placed under constant physical and/or psychological stress. Unlike acute inflammation, which promotes recovery in one part of the body and resolves quickly, chronic inflammation is pervasive and ongoing. The biochemicals that should repair your muscles do the opposite – they destroy tissue and cause cells to malfunction, says San Millan. This can accelerate the body’s ageing process and increase your risk of injuries, arthritis and cardiovascular disease. ‘The dose and duration makes the poison,’ says San Millan, meaning that a little inflammation for a short period can be good, but a lot for a long period can be harmful.
Runners, in particular, need to be aware of the dangers of chronic inflammation because eccentric muscle contractions, (the kind that occur when you run) trigger a heightened inflammatory response. If you tend to log high mileage throughout the year, San Millan recommends getting medical advice on the possibility of having blood tests. Elevated levels of certain biomarkers can be an indication of chronic inflammation.
Of course, high mileage is tricky to define. Everyone has their own threshold for how much their body can handle; one runner’s peak week might be another’s recovery week. And your own baseline ebbs and flows throughout your running life. When you’re in top shape, you may be able to surge beyond your normal limits. At other times, the same training volume could leave you feeling crushed. This is common as athletes get older; recovery becomes more important as the years go by.
Being aware of all of this and adjusting your training accordingly is critical, says Dr Trent Stellingwerff, head of innovation and research for the Canadian Sport Institute. That means training plans that don’t overtax the body and that include recovery. ‘The lowest levels of chronic inflammation you’ll find are in those athletes who are following a smart system that involves exercising between 45 and 90 minutes a day, eating right and sleeping well,’ says Stellingwerff.
On the other hand, runners who go hard but don’t recover properly are more susceptible to chronic inflammation. If you experience difficulty sleeping, night sweats, elevated heart rate upon waking, increased muscle soreness, general fatigue and burnout, you should scale back to reduce your risk and help you have a healthier, happier and longer running life.
Soothe the pain monster
Follow hard efforts with easy days so you heal. Exercise physiologist Inigo San Millan also suggests adding a monthly recovery week, in which you reduce the length and intensity of runs. And have at least one low-impact cross-training day in your weekly routine, to get the increased bloodflow without the stress of impact.
2/ Fuel up
On a run, muscles burn up glycogen. ‘Running on glycogen-depleted legs can lead to inflammation,’ says Dr Matthew Laye, assistant professor of health and human performance at The College of Idaho, US. On runs lasting over an hour, take in a sports drink or gel. And refuel within 30-60 mins of finishing your run.
3/ Eat well
When you’re not performance fuelling, avoid simple sugars in processed foods. Laye says if you overload your body with sugar when your muscles aren’t refuelling, your body struggles to absorb it, which contributes to inflammation. Eat whole, natural foods, some fruit and plenty of vegetables.
4/ Sleep tight
Human growth hormone and testosterone flood your system as you sleep, which helps your body rebuild itself. ‘Shortchanging sleep increases your risk of chronic inflammation,’ says San Millan. ‘You should get at least seven, ideally eight, hours of sleep every night. If you aren’t, cut back on training.’
5/ Stress less
When your brain is overloaded with work or emotional stressors, your body can become deprived of glycogen – the fuel source that feeds your muscles and prevents inflammation. This means that if you are experiencing heavy life stress, it’s critical to eat (and sleep) well. If you can’t, scale back on training until you can.
Head for the pills?
After a hard run, it’s OK to experience muscle tenderness, soreness and even temporary muscle swelling. Under most circumstances, experts recommend letting this natural process run its course without interference. ‘Taking nonsteroidal anti-inflammatory drugs (NSAIDs) can blunt training adaptations,’ says sports medicine specialist Dr Rob Nied. But there are some exceptions to the rule:
> You ran your goal race and are very sore. Take an ice bath and an anti-inflammatory tablet if you want to. Doing so at this point won't disrupt your training gains (training’s done...for now, anyway).
> You twisted your ankle and have visible redness and swelling or severe soreness. Apply ice and consider taking an NSAID for two or three days to treat an acute injury.
> Your plantar fasciitis or Achilles tendinosis is flaring up again. For a chronic overuse injury, you may need to take anti-inflammatories for seven to 10 days. If you’re still in pain after that, make an appointment to see a physiotherapist.