Winter Lurgy: Control What You CAN Control
Will Dyson ·
You can't dodge every bug, but you can stack the odds. Sleep (including the study where they gave people colds on purpose), the flu jab, vitamin D, eating while you're ill and when to train or rest.
Lurgy season is officially open...
Half the train is coughing, anyone who's been on a plane comes home with something (recycled air - thank you for your service) and parents? God bless your poor souls...
Unfortunately, you can't dodge every bug.
BUT you can stack the odds in your favour, and most of it is stuff you're already doing (or should be [points, judgingly]).
Sleep is King
Sleep is one of the most impactful things for infections, and by some distance.
My favourite study on this is pretty mad… They tracked the sleep of 164 healthy adults with wrist monitors for a week, quarantined them, directly put a cold virus up their noses, and observed their susceptibility to getting infected. Compared with people sleeping over 7 hours a night:
- Under 5 hours: 4.5 x more likely to get a cold
- 5-6 hours: 4.2 x more likely
- 6-7 hours: 1.7 x more likely
Small study but pretty clear results that are too hard to ignore for something many of us have/will take for granted.
So 7 hours should be your absolutely non-negotiable minimum and 8 should be the aim. If you can get more, get more. When you're run down, sleep should be the last thing that gets cut; let alone the other mountain of benefits that sleep has on every area of performance and body composition.
Get a Flu Jab
I get one every winter, as there's nothing I hate more than preventable illness derailing a good training block. Firstly, it’s important to recognise that having “a cold” and getting “the flu” are two different things. Cold viruses include things like rhinovirus variants (30-50%), seasonal coronaviruses, RSV and adenoviruses, whereas “the flu” refers specifically to influenza. The former tend to be milder and more of an irritating inconvenience that, in most circumstances, worst case cost you a couple of sessions if you get a bit of a nasty one.
Influenza, on the other hand, is more of a systemic wrecking ball that triggers a massive systemic inflammatory cascade (cytokine release, fever, and direct muscle protein breakdown to liberate amino acids for acute-phase immune proteins), wherein a proper run-in with the flu can easily dampen or wipe out two to three weeks of training and leave your conditioning in the bin. This is precisely the reason why flu vaccines are promoted so broadly, not because of some kind of tinfoil hat wearing illuminati bullshit (please don’t disappoint me with any of that nonsense), but because for the elderly and those that are immunocompromised, a bad case of the flu is potentially lethal.
Mechanistically, a vaccine is essentially an intelligence briefing for your adaptive immune system. Instead of waiting for the live virus to infect your respiratory tract and spend 5 to 7 days slowly building an army from scratch, the inactivated viral particles (antigens) in the jab are taken up by your antigen-presenting cells and shown directly to your T-cells and B-cells. This stimulates the clonal expansion of memory lymphocytes and the production of neutralising antibodies against the haemagglutinin (HA) surface proteins the virus uses to dock onto your airway cells. Collectively, the immune cells that help us fight infections now know what the enemy looks like, such that when the actual virus turns up on the train, in the airplane aircon, on your 4 year old’s jacket picking them up from nursery etc. two months later; your immune system clears it at the door before it can establish a systemic infection.
Bonus Points: Research in exercise immunology shows that doing a bout of moderate to vigorous exercise - particularly resistance training involving the deltoid you're getting jabbed in - shortly before or after your vaccination acts as a natural adjuvant. The acute mechanical stress and localised myokine release draw more dendritic cells and lymphocytes (types of immune cell) through the tissue, significantly boosting your resulting antibody titres Vs simply sitting on the sofa. It's easily accessible for about £20 from Boots, Asda, and most local pharmacies - just try and time it so that if you get 24 hours of mild arm soreness or low grade fatigue, it falls on a planned rest or easy day. I would also recommend prophylactic paracetamol 30 minutes before getting your injection.
Winter Nutritional Supplementation
Before we even talk about any pills or powders, you need to understand that no supplement will ever overcome the impact of 5 hours of sleep and a rundown nervous system. I say this because only about 36% of my clients prioritise sleep like they should and it is the number one contributor to the gap that exists between those that are most successful and consistent in their goal pursuit, and those that yo-yo between happiness and frustration. That said, targeted supplementation is a useful insurance policy across the winter block if you know what’s backed by clinical data versus what’s simply expensive urine.
The smartest way to view winter supplementation is to split your usage into two distinct buckets:
Daily Prevention (October to April) - keep your mucosal barriers and frontline immune cells primed, and
Acute Intervention (When You're Ill) - to aggressively shorten the lifespan and symptom severity of a viral infection.
Daily Prevention (October - April)
Vitamin D3 (4000 IU / 100 µg per day)
While Vitamin D (product here) is traditionally known for regulating calcium and bone metabolism, its role in immune function is just as critical. Your immune cells - particularly monocytes, macrophages, and T-cells - express vitamin D receptors (VDRs). When activated by sufficient circulating levels of 25(OH)D, these receptors upregulate the transcription of antimicrobial peptides like cathelicidin and defensins, forming an essential first line of defence against respiratory pathogens.
Despite its physiological importance, suboptimal status remains a widespread public health issue. In the UK, population surveys show that approximately 20% of adults are vitamin D deficient (<25 nmol/L) during winter and spring, with nearly 60% falling below the insufficient threshold (<50 nmol/L) due to insufficient sunlight (UV-B exposure) between October and April. Globally, vitamin D deficiency and insufficiency are estimated to affect over 1 billion people across all age groups and geographical latitudes, driven by indoor lifestyles, clothing habits, and skin pigmentation.
In a huge meta-analysis of nearly 11 000 participants, daily or weekly Vitamin D supplementation significantly reduced the risk of acute respiratory tract infections across the board, with the biggest protection seen in those starting with the lowest baseline levels. Pair your D3 with Vitamin K2 (like the recommended supplement) and take it with a meal containing fats as both vitamins are fat soluble, meaning they need dietary fat in order to be absorbed effectively.
Echinacea
Taken consistently and daily across the winter months (regardless of if you feel well), Echinacea primes your innate immune system (keeping your frontline white blood cells on high alert) while helping to regulate the inflammatory response so your body doesn't overreact to minor bugs. Mechanistically, active alkylamides in Echinacea bind to cannabinoid-2 (CB2) receptors on your immune cells, increasing antiviral interferon signalling and macrophage activity while dialling down excessive inflammatory cytokines like TNF-alpha that cause the heavy, congested symptoms of a cold. Its constituent compounds also directly interfere with enveloped respiratory viruses to make it harder for them to dock onto your airway cells in the first place.
Importantly, the quality of the extract is important, where across clinical meta-analyses, standardised ethanolic Echinacea purpurea extracts reduce the overall risk of catching a respiratory infection by roughly 25% to 35%, and cut the risk of recurrent infections in half (a 50% reduction) specifically in people under high physical stress or with higher susceptibility. Look for a standardised Echinacea purpurea extract - around 2 400 mg/day across the winter block for prevention, stepping up to 4 000 mg/day at the first sign of catching something. A good quality example with a decades-long track record for quality is A. Vogel, where following the manufacturer recommendations is your best bet.
Vitamin C (1-2 g per day)
Fighting an infection creates a huge spike in oxidative stress, and your immune cells chew through their Vitamin C stores more rapidly while attacking a virus. Specifically, white blood cells like neutrophils and monocytes actively pump Vitamin C across their cell membranes to accumulate intracellular concentrations 50 to 100 times higher than the surrounding blood plasma. When these cells engulf a pathogen, they trigger what’s called a "respiratory burst" - flooding the pathogen with reactive oxygen species (ROS) to destroy it. Vitamin C also acts as the primary intracellular antioxidant shield that stops your own immune cells from being damaged or killed off prematurely by the crossfire of their own chemical weapons, while also supporting T-cell proliferation and chemotaxis (how fast immune cells travel to the site of infection).
During an active infection, leukocyte Vitamin C levels can plummet by 50% within hours as metabolic turnover skyrockets. This is also why context is so important in the research. In Hemilä & Chalker’s landmark Cochrane review of over 11 000 participants, regular Vitamin C supplementation (link here) barely moved the needle on catching a cold in the sedentary general public. However, when they looked specifically at five trials of people under heavy physical stress (marathon runners, skiers, and soldiers in subarctic training), Vitamin C cut the risk of catching a cold in half (a 52% reduction). This is because physical stress from hard training is pro-inflammatory and stretches our immune system and inflammatory management capacity; making it even more important that you support your immune system if you train hard. Furthermore, across the board, higher doses (1-2 g/day) consistently reduced symptom severity (partially due to Vitamin C's natural antihistamine effect) and shaved down cold duration by 8-18%.
Your gut absorbs Vitamin C via saturable sodium-dependent transporters (SVCT1), where if you neck a single 2000 mg dose in one go, transporter absorption drops below 50% and the unabsorbed ascorbic acid sits in your gut, drawing in water and potentially causing you GI distress; hence why high single doses of Vitamin C can cause diarrhoea. As such, I would recommend a daily intake of around 2000 mg split your into two to four smaller doses of 500 mg to 1 g across the day to keep plasma and white blood cell concentrations saturated without upsetting your tummy.
When You're Ill (First 24 Hours Until Symptoms Clear)
Zinc (75-100 mg per day)
Zinc directly interferes with how cold viruses replicate and supports white blood cell production. Timing is extremely impactful with Zinc, wherein starting within 24 hours of your first symptom makes a huge difference (33-40% symptom duration reduction - ~2.5-3 days). There are two ways zinc can help us against viral infections. The first is that it supports the immune system by supporting T-cell development, using tightly controlled cellular signals to keep inflammation in check and other immune system functions. For this I recommend going for 50-75 mg of zinc from well absorbed forms like zinc picolinate or methionine split across the day with food.
The second way (and better way - which I only discovered recently) is that or zinc acetate/gluconate lozenges specifically help with common cold variants in a unique way to tablets/capsules. This is because common cold viruses like rhinoviruses replicate primarily in the nasal and pharyngeal mucosa in the throat, wherein dissolving a lozenge slowly dumps a high local concentration of zinc ions which directly block these viruses from docking.
Beyond rhinoviruses, there are other ways that zinc can support defence against a wider array of viral infections such as inhibiting viral polymerases and proteases (important for their DNA replication, viral particle production etc.) and supporting the mucosal barrier and associated symptoms in number of other ways. Interestingly, Hemila and colleagues showed that lozenges reduced nasal discharge by 34%, nasal congestion by 37%, and cough by 46%; irrespective of the cold variant. For this to work, you need about 4-5 lozenges per day as the benefit is shown at higher doses (75-100 mg/day).
It is nearly impossible to determine what kind of viral infection (e.g. coronaviruses, influenza variants, rhinoviruses etc.) you have which can make it difficult to decide which approach to take; but it stands with good logic to use the lozenges instead (especially if it’s heavy on the throat) as you will absorb the zinc for systemic support anyway. If for whatever reason you can’t tolerate the lozenges, stick with 75-100 mg zinc picolinate/methionine and ensure that you only do so for the 5-7 days you're actually ill, as high dose zinc long term blocks copper absorption.
If you're a client of mine, you'll already have my winter supplement list - echinacea from October to April, plus zinc and vitamin C while you're ill. If you haven't, drop me a WhatsApp and I'll send it over.
Don't “Starve a Cold”…
That old saying "feed a cold, starve a fever" only got it half right… when fighting any respiratory virus, you should feed both. Mounting an acute-phase immune response is metabolically expensive; for every 1°C rise in core temperature, your basal metabolic rate climbs by a whopping ~10-13%, while rapidly proliferating T-cells and B-cells rely heavily on glucose and amino acids (particularly glutamine) to build antibodies and acute-phase proteins.
At a cellular level, a landmark study in Cell demonstrated that while fasting and ketogenesis can be protective during certain bacterial infections, glucose utilisation is strictly required for survival and tissue tolerance during viral infections like influenza to mitigate endoplasmic reticulum (ER) cellular stress induced by antiviral type I interferons. In humans, acute food intake also directly shifts T-helper lymphocyte signalling by boosting production of antiviral interferon-gamma, whereas fasting suppresses it.
From an athletic standpoint, low energy availability (LEA) is one of the strongest predictors of upper respiratory illness in athletes, increasing illness odds nearly 4-fold in Olympic cohorts. Furthermore, training or sleeping in a calorie- and carb-depleted state elevates circulating cortisol and catecholamines, which blunts mucosal immunity and dampens your immune tolerance. If you are currently in a fat loss phase and get hit with a bug, it might be wise to consider hitting pause on the calorie deficit and bring your intake back up to maintenance calories if it looks like it’s going to be more than just a few sniffles until your symptoms and resting heart rate have settled. A 5 day pause at maintenance will cost you zero fat gain, whereas trying to white knuckle a 500 kcal deficit while sick may drag the illness out and performance consequences.
Coulda, Woulda, Shoulda… Rested or Trained?
Cardiovascular Markers
Before you even look at your physical symptoms, your wearable (Apple Watch, Garmin, Whoop, Oura, or morning HRV app) will often flag that your immune system is fighting something 24 to 72 hours before you feel your first symptom. I have spoken many times about the spurious accuracy of wearables for sleep data with appropriate cautioning however, when it comes to illness prediction/identification, there is remarkably good accuracy. Because your autonomic nervous system (ANS) is directly wired into your immune response via the inflammatory reflex, an incubating viral infection triggers a withdrawal of parasympathetic (vagal) tone and a spike in sympathetic drive.
In a massive analysis of 9 million morning measurements, acute sickness and high alcohol intake were by far the biggest physiological stressors on the body, completely dwarfing the autonomic disturbance caused by a brutal training session. Specifically, while a hard training session typically shifts next-morning Resting Heart Rate (RHR) by around +1% and reduces Heart Rate Variability (HRV) by ~4.8%, an acute illness triggers a much sharper spike in RHR alongside a 3-4-fold larger percentage drop in HRV. Similarly, wearable tracking studies show that 63% to 88% of respiratory infections can be detected prior to symptom onset via multi-day elevations in RHR (often >2 standard deviations above your rolling baseline, or roughly +5-10 bpm) and significant reductions in HRV amplitude.
Here’s how to use your morning readiness markers when you feel "a bit off" but aren’t sure how to go about it:
- Resting Heart Rate (RHR): Your RHR is a blunt but highly reliable indicator of systemic stress. If your morning RHR is elevated by 5-8+ bpm without an obvious explanation like a late heavy meal or alcohol, treat your body like it’s fighting off something systemic - even if you don’t have a snotty nose or sore throat! - and take a rest day.
- Heart Rate Variability (HRV): Because vagal-derived HRV is roughly 3-4 times more sensitive to stressors than RHR, it is usually the first domino to fall during the incubation phase of a virus. This doesn’t mean that HRV is better, as greater sensitivity welcomes itself to noise where it’s easiest to think about it this way: if HRV is impacted more easily than RHR, if HRV is outside of it’s usual range, you might raise an eyebrow, but if RHR is, it’s time to raise the alarm. That being said, if HRV drops below your normal baseline alongside a tickle in your throat, pulling back intensity a little isn’t a bad idea.
- Body Temperature: This should be an absolute hard line where a true fever (>37.8-38.0°C core temperature, or a ≥+0.5°C overnight skin temperature difference) is an absolute contraindication to exercise and a sign to rest. For every 1°C rise in core body temperature, your basal metabolic rate increases by ~10-13% and your RHR climbs by ~8-10 bpm as your hypothalamus drives up heat production to try to cook the pathogen. Training with a fever impairs thermoregulation, dehydrates you rapidly, reduces isometric muscle strength and cardiac stroke volume, and drastically increases your risk of exertional heat illness and cardiac complications.
The Neck Check
Once symptoms appear, the classic clinical rule of thumb in sports medicine is the “neck check”, which has actually been tested under controlled laboratory conditions.
Above the Neck Only (runny nose, nasal congestion, mild sore throat, sneezing):
Easy movement is fine - walking, mobility work etc. - and low to moderate intensity exercise. In a series of studies, researchers deliberately gave young adults Rhinovirus-16 (a classic head cold virus) and had half of them complete 40 minutes of moderate cardio at 70% of heart rate reserve (around Zone 3) every other day for 10 days while the control group rested completely. Neither symptom severity, mucous production, nor illness duration differed between the exercise and rest groups, and follow up trials in naturally acquired colds showed the same.
Below the Neck (chest cough, body aches/myalgia, fever, shivers, GI upset, or elevated RHR):
Complete rest. While not many people ever actually want to do so, training through a systemic infection doesn't just drag out your recovery but carries a risk of viral myocarditis (inflammation of the heart muscle), which accounts for up to 8% of sudden cardiac events in athletes. While standard rhinoviruses stay mostly in the upper airways, systemic viruses like influenza, enteroviruses (such as Coxsackievirus B), adenoviruses, and SARS-CoV-2 can be cardiotropic (infecting heart muscle cells directly) or cardiotoxic (triggering immune-mediated damage in the heart).
Animal models show that strenuous exercise during the acute phase of a viral infection drastically increases viral replication inside the myocardium (heart muscle), triples cytotoxic T-cell infiltration, worsens tissue necrosis, and spikes mortality from 5.5% in resting controls to 50% in exercised animals. Because even a systemic/cardiotropic virus can initially present like a mild cold in the first 24-48 hours, always pair the Neck Check with your RHR, HRV, and temperature above over the first few days. And most importantly, you don’t give it to others…
Symptom Management
One of the worst parts of taking a few days off with a bug is that spending 48 hours curled up on the sofa leaves your joints stiff, your back tight, and your sinuses pounding. A few low stress tweaks will keep your body feeling human and ease the burden of symptoms without eating into your recovery reserves:
Keep NEAT & Light Mobility Ticking Over (Above the Neck Only)
If you have a standard head cold with no fever or systemic body aches, sitting motionless all day usually makes you feel groggier. The IOC consensus explicitly supports normal daily activity during mild upper respiratory illnesses. Wrapping up warm for a gentle 20 minute fresh air walk to get some daylight in your eyes, alongside 10 minutes of floor mobility or light stretching, keeps synovial fluid moving through your joints and stops your lower back and hips locking up without spiking stress hormones.
Fluids & Electrolyte Management
Maintaining hydration is essential to keep your respiratory mucous membranes moist so they can trap and clear viral particles effectively in your throat, preventing inward progression early. You don't need to force feed buckets of plain water, but if you have had a mild temperature, night sweats, or drop in food intake, tossing an electrolyte tab or a pinch of salt into your water helps maintain plasma volume and stops that flat, postural lightheadedness when you stand up.
Warm Baths, Steam & Essential Oils Before Bed
Because sleep is your primary weapon for clearing an infection, anything that stops nasal congestion ruining your sleep architecture is a huge win. Using warm baths or steam alongside aromatic compounds like menthol, eucalyptus, and camphor (whether in a bath soak, diffuser, or chest rub) stimulates cold receptors (TRPM8) in your nasal passages, reducing nocturnal cough and subjective congestion so you can actually sleep through the night.
I have suffered with weird gastric and exercise-induced nasal congestion/post-nasal drip for years and use nasal strips to help with this, where I have also found them helpful for sleep. The research on this isn’t strong but I have subjectively found them very helpful, and have found Zone8 to be the best in terms of stickability and performance (TPC10 will get you 10% off too - if you know me, you’ll know that I’m really tight on what I recommend/align with).
Returning to Training
When you have been off training for a bit, treat it like a phased return with a few easy days, progressively ramping things back up once your symptoms are more manageable and RHR has normalised. I’ve said this many times before and I’ll keep saying it until it sticks - consistency is king. Killing yourself for a session or two in exchange for another 2 weeks being set back is not the smart way to handle things. And one silver lining - that won't feel like one while you're cursing into your tissue - is that if you were carrying a lot of training fatigue beforehand, you'll at least come back physically fresher after you’ve recovered.
Summary: The Winter Lurgy Game Plan
Not sure what you should be doing right now? Find the stage that matches how you feel today and follow the guardrails below:
Stage 1: Fighting Fit (Daily Winter Defence)
- Biometrics & Symptoms: RHR and HRV sitting nicely inside your normal baseline; feeling good.
- Training & Activity: Train as programmed. Keep pushing intensity and consistency.
- Nutrition & Lifestyle: Lock in 7 to 8+ hours of sleep per night (non-negotiable). Book your winter flu jab on a planned rest or upper body session day.
- Supplement Stack: Vitamin D3 (4000 IU / 100 µg + K2 with a fat-containing meal) + Echinacea purpurea (2400 mg/day).
Stage 2: Warning Signs (First 24 Hours / Scratchy Throat)
- Biometrics & Symptoms: HRV dropping below baseline or RHR creeping up by 3 to 5 bpm; slight tickle in the throat, sneezing, or feeling 10% "off".
- Training & Activity: Pull back high-intensity intervals and maximal lifts immediately. Cap sessions at 60-70% effort, or swap for a brisk walk and 15 minutes of mobility so you don't dig an autonomic hole.
- Nutrition & Lifestyle: Bring bedtime forward by 60 minutes. If you’re in a calorie deficit, pause the diet and bring calories back to maintenance.
- Supplement Stack: Start Zinc Acetate/Gluconate Lozenges immediately (75-100 mg/day split across 4-5 lozenges) + Vitamin C (1-2 g/day split into 500 mg doses) + step Echinacea up to 4000 mg/day. Keep taking your Vitamin D3.
Stage 3: Above the Neck Only (Standard Head Cold)
- Biometrics & Symptoms: Blocked or runny nose, sneezing, mild sore throat. No fever, no chesty cough, no body aches, and RHR <5-10 bpm deviation.
- Training & Activity: Keep NEAT ticking over with daylight walks and light stretching to keep your body from feeling like it’s seizing up. If you want to train, stick strictly to low to moderate intensity (<70% effort) and stop if you feel worse 15 minutes in.
- Nutrition & Lifestyle: Eat at maintenance calories with plenty of protein and micronutrients. Keep mucous membranes (remember those important first line barriers) hydrated with fluids and electrolytes, and use warm baths or menthol/eucalyptus aromatics before bed to clear your airways for sleep.
- Supplement Stack: Continue acute protocol (75-100 mg Zinc lozenges + 1-2 g split-dose Vitamin C + 4,000 mg Echinacea + 4,000 IU Vitamin D3) for 5 to 7 days until clear.
Stage 4: Below the Neck (Systemic Bug / Flu)
- Biometrics & Symptoms: Fever (core temp above 37.8°C or +0.5°C wearable deviation), RHR spiked by 5-10+ bpm, shivers, muscle/joint aches, chest cough, or GI upset.
- Training & Activity: Complete rest. Zero gym sessions and zero cardio until fever and systemic symptoms have completely resolved and RHR returns to baseline.
- Nutrition & Lifestyle: Eat at maintenance (or as close as appetite allows using easy to digest and throat friendly carbs, soups, smoothies, and protein) to fund the immune response and protect lean muscle mass. Prioritise aggressive hydration and consider some basic sodium/electrolytes to cover fever sweat losses if you’re running hot.
- Supplement Stack: Full acute supplement stack alongside appropriate over-the-counter symptom relief (like paracetamol for fever) so you can rest comfortably.
Post-Illness: Phased Return (Symptoms Cleared)
- Biometrics & Symptoms: Fever-free (without medication, if relevant), systemic symptoms gone, and morning RHR/HRV returned to their normal ranges.
- Training & Activity: Don’t jump straight back into any savage workouts or PB attempts. Run 2 to 4 days of progressively ramped sessions (starting at 60-70% of your usual intensity and monitoring how your heart rate responds during and 24 hours after) before resuming full programming.
- Nutrition & Lifestyle: Stay at maintenance calories for your first few sessions back before reintroducing any caloric deficit.
- Supplement Stack: Drop the high dose Zinc after 5 to 7 days (to avoid blocking copper absorption) continuous use and return to the baseline winter prevention stack (Vitamin D3 + Vitamin C + preventative Echinacea).
Protect your sleep above everything else.
And as I say to every client at this time of year... control what you CAN control.
Coach
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