News
8 Minutes
30/10/2026
Research suggests genes explain part of the difference. Variants in seven genes, SOD2, TNF, IL6, IL6R, CRP, GSTM1 and GSTT1, influence how much damage builds up during exercise, how strongly and how long inflammation runs afterwards, and how quickly your cells clear the by-products. Sleep, nutrition and stress shape recovery just as much.
An hour in the gym or a Sunday morning run feels like the hard bit. It isn’t. Exercise only creates the stress; the fitness comes afterwards, in the 48 hours your body spends repairing, cleaning up and rebuilding slightly stronger.
That window looks very different from one person to the next. After the same bootcamp class, one person is ready to go again the following day. Another feels heavy-legged until Thursday, and if they train anyway, they start the next session already behind. Once you know how you recover, you can plan a week that works with your body rather than against it.
This article explains:
Most recovery happens in the 48 hours after a hard session, though a very demanding workout can take longer. Recovery works like a relay. Each stage hands over to the next, and a different set of genes runs each leg.
| When | What happens | Genes involved |
|---|---|---|
| During exercise | Free radicals build up in working muscle | SOD2 |
| Straight after | Immune cells and muscle send out repair signals | TNF, IL6, IL6R |
| 24 to 48 hours | Inflammation peaks and soreness sets in | CRP |
| Throughout | Cells clear waste and by-products | GSTM1, GSTT1 |
When every leg runs smoothly, you feel normal within a day or two. When one stage runs slowly, the whole relay backs up.
Exercise makes your muscles burn far more oxygen than usual. A small share escapes as free radicals, unstable molecules that damage cells if left unchecked. In small amounts they serve a purpose: they tell your body it needs to adapt.
Long name: superoxide dismutase 2
What it does: neutralises free radicals inside your mitochondria, the structures that produce your energy
Recovery connection: how much exercise damage carries over into the following days
SOD2 works at the source. Your mitochondria make most of the free radicals produced during exercise, and SOD2 is the first line of defence: it converts them into less harmful molecules that other enzymes then finish off. Some versions of the gene get less SOD2 into the mitochondria, so free radicals build up faster when you train hard without enough recovery.
| Genotype | Antioxidant protection | Recovery priority |
|---|---|---|
| TT | Good | Standard |
| CT | Moderately reduced | Higher |
| CC | Reduced | Highest |
As you finish a session, your body sounds the alarm. Immune cells and working muscle release chemical messages that call in the repair crew, and three genes shape how loud those messages are.
TNF: the alarm
Immune cells release TNF when they detect damage, and it triggers other signals, including IL-6. Some versions of the gene produce more TNF, linked to a stronger response.
IL6: the messenger
Working muscle makes IL-6 itself, and it helps release fuel and start repair. Some versions of the gene produce more IL-6 in response to stress.
IL6R: the receiver
IL-6 only works once it docks onto its receptor, which sits on some cells and also floats freely in the blood. Variants in IL6R shift the balance between the two, changing how strongly your body feels the signal.
A brief spike in these signals after exercise is healthy, and regular exercise lowers your resting levels over time. The problem comes when the signals stay switched on and the repair crew is still at work when your next session starts.
IL-6 has a knock-on effect. It tells your liver to make C-reactive protein, a marker that rises while inflammation is active. After strenuous exercise, CRP climbs over the following day or two, around the time delayed onset muscle soreness (DOMS) peaks.
Long name: C-reactive protein
What it does: flags damaged cells so your immune system can clear them away
Recovery connection: how long inflammation lasts after hard exercise
Some versions of the CRP gene are linked to higher levels after demanding exercise. If you carry them, your body may need a longer gap before your next hard session.
You can also measure CRP directly. An hsCRP blood test picks up the low levels that reflect ongoing, low-grade inflammation: your CRP genes shift your baseline, and the blood test shows where your levels sit right now.
Hard exercise raises CRP for a day or two, so avoid strenuous sessions before an hsCRP test to make sure the result reflects your baseline.
“Fitness isn’t built in the session; it’s built in the two days after it.”
While inflammation repairs the damage, a separate team clears the debris. Glutathione S-transferase enzymes attach your body’s own antioxidant, glutathione, to toxins and the by-products of oxidative stress, which makes them easier to flush out.
Long name: glutathione S-transferase M1 and T1
What they do: clear toxins, by-products and free radicals from your cells
Recovery connection: fatigue and recovery speed after demanding exercise
These two genes work like a light switch rather than a dimmer. Most genes come in slightly different versions; GSTM1 and GSTT1 are either present or null. Present means you have at least one working copy. Null means both copies are deleted, so your body makes none of that enzyme.
A null result is common, and most people never notice it day to day, because other enzymes share the load. After hard exercise, though, it can mean more oxidative stress, more fatigue and a slower bounce-back. Being null for both genes may have a bigger effect than being null for one.
| Result (each gene) | What it means | Recovery priority |
|---|---|---|
| Present | Enzyme made and working normally | Standard |
| Null | Both copies deleted; no enzyme made | Higher |
You can’t switch a missing gene back on, but you can support the enzymes you do have. Cruciferous vegetables help your body make more of its other detox enzymes, which helps make up the difference.
A DNA test shows your genetic tendency, not your day-to-day readiness. Your Stride recovery efficiency report reads seven variants across these seven genes, covering every stage of the relay. It weighs each variant you carry and combines them into a single rating for how efficiently you recover.
If you have read about the injury predisposition report, four of these genes will look familiar. IL6, IL6R, CRP and TNF appear in both, because the inflammation that repairs a tired muscle also decides how well tendons and joints cope with repeated load.
Your rating does not change what you can achieve. It changes how you arrange your week. Here is how the same mix of strength, cardio and a weekend game might look for a faster and a slower recoverer.
| Day | Faster recovery | Slower recovery |
|---|---|---|
| Monday | Strength session | Strength session |
| Tuesday | Run or class | Walk or gentle cycle |
| Wednesday | Easy day | Run or class |
| Thursday | Strength session | Rest |
| Friday | Rest | Easy day |
| Saturday | Long run, ride or match | Long run, ride or match |
| Sunday | Easy day | Rest |
If your result sits in the middle, keep at least one easy day after every demanding session, and judge your next workout by how you feel on the second morning.
Your genes set your starting point. Your habits decide how much of it you use.
Each variant in the report has a small effect, and research on several of them is still developing. A stressful week at work or a run of bad nights can slow your recovery as much as a hard session, whatever your DNA says.
How long should I rest between workouts?
It depends on how hard the session was and how quickly you recover. Most people need at least a day between demanding sessions that work the same muscles, and slower recoverers may need two. Easy movement in between is fine and often helps.
Is it okay to exercise when I’m still sore?
Gentle movement, such as walking or an easy cycle, usually helps soreness ease. Avoid another hard session on the same muscles until the soreness has faded, because your body is still repairing them.
Should I take antioxidant supplements to recover faster?
Not without thought. Research suggests that high doses of some antioxidant supplements taken around exercise may blunt the signals that help your body adapt. Food is the safest place to start, and if you are considering supplements, speak to a healthcare professional first.
Why does recovery feel slower as I get older?
Research suggests recovery does slow with age, as muscle repair and hormone levels change. Your genes stay the same, but regular strength training, good sleep and enough protein all help you bounce back better at any age.
What is DOMS and how long does it last?
DOMS, or delayed onset muscle soreness, is the ache and stiffness that appears a day or so after unfamiliar or demanding exercise. It usually peaks one to three days after the session and fades within a few days. Gentle movement, good sleep and enough protein all help it ease.
Which genes affect exercise recovery?
Research links several genes to exercise recovery. SOD2 affects antioxidant protection during exercise; TNF, IL6 and IL6R shape the inflammatory response afterwards; CRP influences how long inflammation lasts; and GSTM1 and GSTT1 affect how well your cells clear by-products. Each has a small effect, and habits such as sleep and nutrition matter just as much.
Recovery is where exercise turns into fitness, and your genes influence how fast each stage of it runs.
Knowing your recovery efficiency lets you arrange your week so every hard session lands on a body that is ready for it.
Your result is part of the Stride fitness report, included with the Optimal DNA & Methylation Test.
Answer 8 quick questions and get a free personalised report - covering which area of your biology is most worth looking at first, what testing in that area reveals, and what actions become available once you have that data.
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