Your last cold was a warning

Most people file getting sick and getting injured under different headings. One is bad luck. Someone at work was coughing, the kids brought something home from daycare, it is that time of year. The other feels like a mistake. You went too heavy, you skipped the warm up, you should have known better.

They are more closely related than that. A lot of the time they are the same problem turning up in two different places.

Both jobs come out of the same tank

Training does not build you. It damages you in a controlled way, and then your body rebuilds, mostly overnight and mostly out of what you have eaten. Fighting off a virus draws on that same repair and immune capacity. So does healing a tendon that got a bit more than it wanted last Thursday.

When that capacity is short, both jobs get done badly at once. You pick up whatever is going around the office, and the calf that has been grumbling for a fortnight finally lets go. Those two events look unrelated. Often they are the same event.

There are four things that drain the tank faster than almost anything else.

1. Sleep

The immune evidence here is unusually clean, because researchers have done the experiment properly. Volunteers were tracked for their normal sleep, then deliberately exposed to a cold virus. The short sleepers, under about seven hours, were several times more likely to actually develop a cold than the people getting eight or more. Same exposure, different outcome.

The injury side lines up. Work in young athletes has found that sleep duration predicted injury better than training hours did. Athletes averaging under eight hours a night were substantially more likely to be injured than those getting eight or more. Not more likely to feel tired. More likely to get hurt.

Both effects run through the same door. Short sleep means less growth hormone release, worse glucose handling, higher inflammatory signalling, blunted immune response, and slower tissue repair. On top of the biology, tired people move worse and make worse decisions late in a session.

In practice: the end of your sleep is largely outside your control. The start is not. Most people who are chronically short are short because they go to bed late, not because they wake early. Consistency of timing matters more than any gadget. Alcohol in the evening will get you to sleep and then wreck the second half of the night, which is the part doing most of the repair.

And if your sleep is genuinely not fixable right now, because of a newborn or shift work, then the answer is not to keep training as though it were. Reduce what you are asking of your body until the sleep comes back. That is not defeatism, it is arithmetic.

2. Everything else going on in your life

This is the one people skip, because it does not feel like it belongs in a training conversation.

Sustained stress raises cortisol, which dampens immune response and slows tissue repair. That is the direct route. The indirect route is bigger. Stressed people sleep worse, eat more erratically, drink a bit more, skip warm ups, train distracted, and are less honest with themselves about how a session felt.

Studies in athletes have repeatedly found that periods of high life stress predict injury independently of training load. The stress does not have to be dramatic to count. A new baby, a difficult period at work, money pressure, a relationship going through something, a parent unwell. Your body does not run separate accounts for stress from the gym and stress from the rest of your life. It has one account.

In practice: you usually cannot remove the stressor, so treat the stressful period as a period of reduced capacity and plan accordingly. Holding steady through a hard three months is a legitimate goal. It is not the time to add a fourth session or chase a personal best.

3. Fuel

Not eating enough to cover what you are doing is the big one, and it is far more common than people think. It shows up in two groups: people training hard while trying to lose weight, and people who are simply busy and keep skipping meals without noticing.

Persistently low energy availability is associated with more frequent illness, poorer bone health, slower repair, disrupted sleep, and higher injury rates including bone stress injuries. The body prioritises. When intake is short, functions that are not immediately essential get downgraded, and immune function and tissue remodelling are exactly the sort of thing that gets downgraded.

Protein is the raw material for the rebuild. Somewhere around one and a half to two grams per kilogram of body weight per day is the range usually quoted for people training seriously, spread across the day rather than loaded into dinner. That is a rough guide rather than a prescription, and if you want it worked out properly for you, a sports dietitian is the right person.

Alcohol compounds all of it. It impairs muscle protein synthesis, disrupts sleep architecture, and does you no favours immunologically.

In practice: eat something around your training rather than after a six hour gap. Be suspicious of any week where you cannot remember what you ate for lunch. If you are deliberately in a deficit, accept that your training capacity is reduced for that period and pull the load back to match.

4. Load spikes

Your tissues tolerate what they have been prepared for. What causes trouble is not high training load, it is a sharp rise relative to what you have been doing recently. Unusually hard or long sessions also cause a temporary dip in immune function afterwards, which widens the window for picking something up.

The classic scenarios are predictable: the start of a new program, the first weeks of a season, coming back after a holiday or an illness, a friend talking you into an event, or a single enormous weekend after a quiet month. Fitness improves faster than tendon and bone adapt, so for a few weeks you feel capable of more than your tissue is ready for. That gap is where things tear.

In practice: change one variable at a time. Put your hardest session after your best night of sleep, not on a Monday after a bad one. The first week back after illness or a break is a rebuild, not a resume from where you left off.

What the pattern actually looks like

Someone starts a new program in February. Three good weeks, feeling strong, adding a bit each session. Week four they get a head cold and train through it, because it is just a cold. Week five they are still a bit flat. Week six they strain a calf on a run and put it down to bad luck.

Two unrelated misfortunes, or one story with an obvious middle chapter. The cold was the first thing to break, because immune function is the first thing that gives when recovery falls behind. The calf was the second.

When a cold is just a cold

Worth being honest here. Sometimes it really is bad luck. If you have small children, work with the public, or live through a Darwin build up with the air conditioning recycling everybody's germs, you will get sick more often regardless of how well you are sleeping. One cold means nothing.

The signal is the pattern rather than the single event. Getting sick more often than is normal for you. Things taking longer to clear than they used to. Illness sitting alongside a niggle that will not settle. Waking unrefreshed after a full night. Motivation flat, performance drifting down without an obvious reason.

If several of those are true at once, that is not a run of bad luck. That is your capacity telling you something.

The useful part

Illness is an early warning, and early warnings are valuable because they arrive before the expensive thing happens. A week of feeling rotten costs you a week. A hamstring tear or a bone stress injury costs you three months and a season.

So if you have been getting sick more than usual lately, treat it as information about your capacity rather than information about your luck with viruses. Sort out the sleep. Eat enough for what you are actually doing. Be honest about what else is going on in your life at the moment. Ease the load back for a few weeks rather than pushing through.

Both risks come down together, because they were never really two risks.

Not sure where your load is at?

If you are run down, picking up every bug going around, or carrying a niggle that will not settle, a physiotherapy assessment can help you work out what needs to change before it turns into an injury. We will look at your training history, your recovery, and the tissue that is complaining, and give you a plan you can actually follow.