Why do you always feel the burn on the second day after a big workout?

Image: Parks and Rec.

Last year, I tried my first reformer pilates class. I had a flight to South Africa booked in two days later but figured the bulk of my post-pilates ache would be over by the time I reached the airport, so I wasn’t too concerned.

Alas, I was very, very wrong. When the session wrapped up, our instructor proffered a dire warning: “You probably won’t feel it tomorrow, but the day after, you definitely will.” Unfortunately for me, he was absolutely spot on, and I endured an extremely achey 14 hours in the air.

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A bit of soreness (or “the burrrrrn“, as fit people love to call it) after exercising is to be expected, but I’m consistently surprised by how the full force of my workout tends to hit a full two days after the fact. Day one is bad enough, but then boom — I find myself walking like… well, someone much older than my 26 years.

This phenomenon has a name: delayed onset of muscle soreness, or DOMS. It’s characterised by tenderness and soreness in your muscles, which peaks 48-72 hours after your workout is done. (Post continues after gallery.)

“DOMS frequently occurs following unaccustomed or strenuous exercise, and in particular, with strength training … [it] is largely caused by exercise-induced micro trauma to your muscle fibres,” explains Katie Lyndon, Accredited Exercise Physiologist at Exercise & Sports Science Australia.

If you’re anything like me, you probably just saw the word “trauma” and felt immediately guilty for what you’ve been inflicting on your muscles. (Sorry, guys — promise I didn’t mean to cause you harm!)

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However, this isn’t something you should be too concerned about; Lyndon says a mild degree of micro-trauma is actually beneficial. “It facilitates improvements in muscle strength and hypertrophy, or toning, as these muscle fibres repair and rebuild,” she explains.

As for why the pain is so much more concentrated on day 2 or 3, personal trainer and Pick It Up! Fitness founder Michael Genitsaris says this comes down to the adaptation process. ”

After a strenuous workout, your body realises that it needs to start getting stronger so that next time you undergo that workout it will be easier and more efficient. However this process doesn’t happen immediately,” he explains.

"Between completion of your workout and the final stage of muscle adaptation, a whole bunch of science stuff happens to help repair and strengthen those micro tears in your muscles. This process can take up to a few days depending on the severity of the micro tears, which is why sometimes muscles soreness can be at its worst 24-48 hours post-workout."

That doesn't mean you won't also feel the burn in the immediate aftermath — Genitsaris says mild pain at this stage is very common and isn't anything to worry about, as long as it's centralised to your muscles. So don't panic if you experience a reduced range of motion, or muscle swelling or stiffness in the days after your workout.

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"However if there is any sharp pain in your joints, or shooting pain like an electric shock during or after a workout, debilitating pain or sever decrease in limb functionality, it would be the correct time to stop and seek some advice or help from a professional," Genitsaris adds.

Post-workout muscle pain varies from one person to the next, and Lyndon says this is largely determined by how much your body is used to fitness or a certain type of exercise. So while I find walking, sitting and just about any physical movement painful two days after a workout, the person next to me at the gym might only suffer a mild ache. That's probably because my approach to fitness is shamefully inconsistent. (Post continues after video.)

If you endure DOMS, the good news is your aches and pains will go away... well, eventually.

"The soreness will increase in intensity in the first 24 hours after exercise and should subside and disappear up to 6-7 days following exercise," Lyndon explains.

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Until that happy, pain-free day comes, it's generally wise to avoid any vigorous workouts that might build on your existing pain; opt for something low-impact like walking or swimming until you're back to normal.

"Eccentric [i.e. lengthening] exercises significantly contribute to DOMS, so to minimise this discomfort and pain try not to focus too much on these types of movements," Lyndon recommends.

"Be sure to warm up properly before any workout and include dynamic stretching before and static stretching after a workout. Other remedies that may help to ease the pain are ice, rest, anti-inflammatory medication, massage and heat," Genitsaris adds.

Although there's no miracle cure for DOMS (if only!) there are some steps you can take to prevent it, or at least reduce its severity.

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"Make sure you are gradually progressing your workout and exercises over a period of weeks, as this will allow your body to become accustomed to different movements, reducing soreness and also avoiding injury," Lyndon says.

This is particularly important for exercise beginners — Genitsaris says to take things slow, and expect some form of stiffness at first. "Remember as long as the pain is localised to your muscles don’t stress. This is just a sign that your muscles are adapting and getting stronger!" he adds.

When do you feel the post-workout burn? How do you ease the pain?