What Movement Actually Does to Your Immune System

You probably didn’t think about your immune system during yesterday’s Pilates class. Something specific was happening anyway. Within minutes of starting, the white blood cells that do the most important work against winter viruses were up to five times more concentrated in your bloodstream than they were when you walked in.

It happens every time you move. Strength, Pilates, mobility, yoga — any of it. And the cumulative effect through May, June and July, when respiratory infections spike and the supplement aisle gets at its loudest, is much bigger than most people realise.

The single most studied non-pharmacological immune lever in the research isn’t on a shelf. It’s the kind of moderate-intensity movement we do at All for One every week. Here’s what’s actually happening — and why this is exactly the season to keep showing up.

What’s happening to your white blood cells while you’re in class

The first surprise is how fast it works.

Within minutes of starting a session, your circulating natural killer (NK) cells — the white blood cells responsible for the first wave of defence against viruses and abnormal cells — increase up to fivefold. Lymphocytes overall jump two to three times. CD8+ T cells and γδ T cells, your immune system’s specialist viral fighters, surge into your bloodstream and get redistributed to the tissues most exposed to infection.

This isn’t a wellness claim. It’s a measurable, replicable, dose-dependent response, driven by adrenaline binding to β2-adrenergic receptors on those exact cell types. Each session is essentially a brief immune surveillance sweep — your most potent infection-fighting cells get mobilised, redistributed, and re-deployed to where they’re most useful.

Done week in and week out over winter, the cumulative effect is meaningful: stronger immune surveillance, lower chronic inflammation, and a measurable shift in how your body responds when something does come along.

What that translates to in real life

The cellular activity shows up in three specific outcomes the research is now clear on.

Shorter, milder colds when you do get one. A Cochrane review of exercise and acute respiratory infections found regular movement doesn’t change how often you catch something, but it consistently reduces severity and duration. Fewer symptom days, less time off work, a quicker return to feeling normal.

A measurable boost to vaccine response. Studies in older adults have shown that moderate movement improves antibody response to flu and pneumococcal vaccines. A 90-minute session of moderate-intensity exercise around the time of vaccination consistently increases serum antibody levels four weeks later. A brisk walk before your jab does more than most of us realise.

Lower risk of severe respiratory infection overall. Active people had measurably lower risk for severe COVID-19 and other acute respiratory infections than sedentary people — a finding that held across dozens of studies during and after the pandemic.

The dose, and why it matters

The catch with movement and immunity is that more isn’t always better.

The relationship is shaped like a J. Moderate-intensity movement raises immune function meaningfully above sedentary levels. Very intense or very prolonged training — back-to-back high-intensity sessions, marathons, ultra events — causes a temporary 3 to 24-hour dip in immune function known as the “open window,” where you’re actually slightly more vulnerable to whatever’s going around.

For everyone reading this, that’s good news. The dose that delivers the immune benefit is exactly the dose we build into your weekly mix at All for One — moderate-intensity strength, Clinical Pilates, mobility and yoga, four or so times a week, with proper recovery between sessions. Our classes aren’t accidentally at this intensity. They’re designed at it. The research case for why our weekly mix works for your body is also the research case for why it works for your immune system.

You don’t have to push harder to get the benefit. In fact, the people who do — the ones who try to train through illness, double up sessions, ignore the recovery — move themselves into the open window the studies warn about. Smart load matters more than heroic load. That’s something our coaches will check with you any time you ask.

What the supplement aisle gets wrong

A few honest notes on what to expect from the alternatives, since most people will hear the pitch this month.

Vitamin C does not prevent colds. The evidence on regular high-dose vitamin C for cold prevention has been consistently negative across decades of research. It may shorten the duration of a cold if taken consistently (not just at the first sniffle), but the effect is modest and well below what consistent movement delivers.

Zinc lozenges can shorten a cold by 30 to 40 percent — but only if you start them within the first 24 hours. That’s a real, useful finding. It’s a treatment, though, not a prevention strategy.

Most “immune boosting” supplements aren’t supported by clinical evidence. Mushroom blends, elderberry, gummies — the trial data simply isn’t there. The exception worth checking is vitamin D, which a lot of Australian adults are mildly deficient in by mid-winter, and which does play a real role in immune function.

What actually works is unfashionable and free: moderate regular movement, 7 to 9 hours of sleep, hand washing, vitamin D if you’re low, and managing stress. Five things — three of which we help you build at All for One every week.

The case for showing up through May, June and July

The reason supplement companies push hardest from May onwards is because that’s when the audience is most worried about getting sick. They aren’t wrong about the worry. They’re wrong about the answer.

The evidence-based version is also the boring one: keep coming to class, sleep well, get your vitamin D checked if you haven’t, wash your hands. The single most useful thing you can do for your immunity through the cold months is what your weekly Pilates and strength sessions are already doing — and the members who keep that up through winter come out the other side having spent fewer days sick than those who pulled back.

We’d love to see you in the studio.