The Dublin Marathon is on Sunday 25 October. If you're reading this in early October, the big training blocks are done. Nothing you do in the next three weeks will build much new fitness.
What these three weeks can do is decide how much of that fitness you actually bring to the start line, and how much of it survives past the 20-mile mark.
Most taper advice is about miles and carbohydrates. This guide is about the part that usually goes first in the second half of a marathon: your tendons, ligaments and joints. Here's what to do with them in the final three weeks, on race morning, and in the fortnight after.
Why your tendons decide the last 10km
Your muscles produce the power, but your tendons deliver it. Every stride, your Achilles and the tendons around your knee stretch and recoil like springs, returning energy that your muscles would otherwise have to find.
Over 42.2km that adds up to around 40,000 foot strikes. When those springs are well conditioned, more of each stride's energy goes into moving you forward. When they fatigue, your stride shortens, your muscles take on more of the work, and your pace drifts. Fuel gets most of the blame for late-race slowdowns, but a shortening stride is often part of the story too.
So the goal for the taper isn't simply to feel less sore. It's to arrive with connective tissue that's had time to absorb a summer of training and is ready to do its job for three-plus hours. Recovery matters too, and we'll come to it, but performance is the point.
Weeks three and two: lock in the work
This is when your body catches up on the training you've already done. Connective tissue adapts more slowly than muscle, so the reduced volume of the taper is when tendons and ligaments get the chance to consolidate.
- Keep some intensity. Cut volume, not all your quality. Short race-pace efforts keep tendons used to the loading they'll face on the day.
- Time your collagen around those sessions. A 2017 study in the American Journal of Clinical Nutrition (Shaw et al.) found that taking collagen with vitamin C before a short bout of exercise increased markers of collagen synthesis. The practical takeaway: take it 30–40 minutes before you train, so it's available while your tendons are being loaded. A 2026 systematic review points to a similar window; we covered it in what the latest tendon research actually found.
- Rest days count too. On days off, take it with breakfast. Repair doesn't stop because you're not running.
- Don't introduce anything new in race week. If you're going to start a supplement, these two weeks are the time to do it, so you know how it sits with you before the day.
Race week: change nothing
Race week is about keeping everything familiar. Your legs may feel heavy or twitchy as volume drops. That's normal, and it's not a sign you've lost fitness.
- Keep your routine exactly as it was. Same breakfast, same supplements, same timing. Your short shakeout runs are still sessions, so keep taking it 30–40 minutes before them.
- Carb-load as planned, and drink to thirst. Your stomach is already busy. A single liquid sachet is easier to fit in than another scoop of powder in another shake.
- Check anything you take is batch-tested. If you race competitively or in a club, look for Informed Sport certification. It means every batch is tested for banned substances before it's released.
Race morning: same as a long run
The rule on race morning is simple: only do what you've done before your long runs.
If you've been taking a sachet 30–40 minutes before training, do the same before your wave goes. A sachet fits in a pocket and needs no water or mixing, so you can take it in the start area without any fuss. If you haven't practised it, leave it out on the day and pick it up again afterwards.
The fortnight after: recover, then rebuild
The marathon is the biggest single load your tendons and joints will take all year. The stiffness on the stairs on Monday is the obvious part. The less obvious part is that connective tissue keeps remodelling for weeks after the soreness has gone.
- Days one to three: walk, sleep and eat properly. Keep taking your collagen with breakfast, as you would on any rest day.
- Days four to fourteen: easy runs or cross-training when your legs say yes. Go back to taking it 30–40 minutes before those sessions.
- Watch for pain that isn't going away. General stiffness should ease within a few days. Sharp or worsening pain around the knee or Achilles is a reason to see a physio. Our runner's knee recovery plan covers one of the most common.
This is also where the recovery benefits come in. Better-supported joints and tendons can mean less stiffness and an earlier return to running, which matters as much for your next race as this one.
Where OOST ReGen & Recover fits
OOST ReGen & Recover is a single-dose liquid sachet built for exactly this kind of training block. Each one combines:
- 8,000mg marine collagen, hydrolysed into small peptides
- Vitamin C, which your body needs to make collagen
- Glucosamine sulphate and chondroitin, building blocks of cartilage
- Vitamin D, for bone and muscle function
- Curcumin with piperine, the active compound in turmeric plus black pepper extract
It's Informed Sport certified, so every batch is tested for banned substances.
How to take it: one sachet 30–40 minutes before training, so the collagen is available while your tendons and ligaments are working. On rest days, take it with breakfast.
When to take it: read the full Pre-Training Protocol for the research behind the timing.
FAQs
Is three weeks enough time for collagen to make a difference?
Connective tissue changes slowly, so three weeks won't transform it. What it can do is support the repair that's already happening as your volume drops. The bigger gains come from taking it consistently over a full training block.
Should I take collagen on race morning?
Only if you've already taken it before long runs. Nothing new on race day.
When should I take collagen during a marathon taper?
30–40 minutes before each session, and with breakfast on rest days.
How long after the marathon should I keep taking it?
Keep going through the two-week recovery period and into your next block. Connective tissue keeps remodelling well after the soreness has gone.
Is OOST suitable for tested athletes?
It's Informed Sport certified. Every batch is tested for substances on the WADA prohibited list before it's released.
Take it further
You've done the miles. The next three weeks are about arriving at the start line with everything you built still intact, and recovering well enough afterwards to go again.
For the full picture on how collagen supports runners beyond race season, read our Runner's Guide to Collagen.
Good luck in Dublin.
Take It Further.
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Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. If you have any pre-existing medical conditions, are taking medication, or are pregnant or breastfeeding, consult your doctor before use.
