---
title: "Tilt the bed, get faster?"
date: 2026-07-19
categories: ["Recovery & sleep","Training"]
url: https://www.semiprocycling.com/digest/tilt-the-bed-get-faster
author: Damian Ruse (SEMIPRO Cycling)
---
# Tilt the bed, get faster?

[Listen to this issue as a podcast](https://www.buzzsprout.com/6262/episodes/19511317)

![](https://www.semiprocycling.com/digest/images/352d20a3a8cd1d7f432ac2ae.webp)

Riders spend real money chasing red blood cells. Altitude camps. Heat sessions. Tents that turn your bedroom into a hypoxic chamber and your sleep into a science project. All of it aimed at the same thing: more haemoglobin, so you can carry more oxygen, so you can hold more power for longer.

So here is a study that is either a gift or a wind-up, depending on how you read it. A group out of Denmark and Poland, from Carsten Lundby's world of altitude and blood physiology, asked a simple question. What if you just tilted the bed?

Nine men slept two ways, five weeks each, in a randomised crossover. In one block they slept flat, as everyone does. In the other they slept with the whole bed tilted six degrees head-up. That is it. Not head propped on pillows. The entire bed on a slight downhill, feet lower than head, all night, for five weeks. Blood volume, haemoglobin mass and EPO were measured along the way.

## What they found

After five weeks of head-up sleeping, total haemoglobin mass rose from 943 g to 979 g. A gain of 36 g. Red cell volume climbed by around 105 mL, and total blood volume expanded by about 4 per cent. In the flat condition, nothing moved.

Thirty-six grams of haemoglobin is not a rounding error. It is roughly the kind of gain you might chase from a proper block of altitude, or from a solid stretch of training. Here it came from furniture.

Now the honest part, because this is where most write-ups of this study go wrong.

The headline you will see is "sleeping on a tilt boosts your EPO." That is the presumed mechanism, and it is a reasonable one. Lying flat pushes central venous pressure up. Tilt the bed and that pressure drops a little overnight, and a sustained drop in central venous pressure is a known trigger for EPO release. Blood settling lower in the body, the kidneys reading the change, the machinery that builds red cells switching on. That is the story on the slide, and it probably is the pathway.

But in this study, resting EPO did not actually differ between the two conditions. The red cells went up. The resting EPO reading did not. Most likely the EPO signal is small and comes in the night, so a daytime blood draw walks straight past it. The point is this: the outcome that matters, the red cells, is real and was measured directly. The EPO explanation is a good theory sitting underneath it, not a number you can point to. Anyone telling you this study "proves your EPO went up" has not read it carefully.

## Where to be careful

Nine people. All men. Not described as trained cyclists, and that matters, because a rider who already carries a high haemoglobin mass has far less room to gain than an untrained starting point. The five weeks bought 36 g here. In someone already close to their ceiling it may buy much less. And more haemoglobin is not the same as more race performance. It is one input, and this study did not test what happened to actual power or times. Finally, adding red cells thickens the blood, so anyone with any history of clotting problems should not go near this without a doctor.

So: a real, directly measured effect, from an almost free intervention, with a plausible mechanism and a small honest asterisk over the EPO claim. Interesting. Not magic.

## What to do with this

**If you race.** Do not bin a single training session for this. It is not a substitute for the work and it never will be. But if you are already doing the expensive things, an altitude block or heat work before an A race, this is a cheap, passive thing to stack alongside them. Raise the head of the bed properly, from the frame, not with pillows, and give it the full five weeks. If you can get a haemoglobin mass test either side, even better. Measure, do not assume.

**If you have the hours.** Your haemoglobin mass is probably already high from all that riding, which means your ceiling for gain here is lower than a beginner's. That is not a reason to skip it. It costs nothing and it costs no recovery, which is the rarest combination in this sport. Just keep your expectations honest and do not expect furniture to do what your long rides already do.

**If you are time-capped.** This is the one that should make you sit up. Almost everything that builds fitness costs you time or costs you recovery, usually both. This costs neither. You sleep anyway. If there was ever a marginal gain worth trying for a rider with no spare hours, a passive adaptation that runs while you are asleep is it. Raise the bed around 15 cm at the head end and forget about it. Treat anything you get as a bonus on top of the training, not a replacement for it.

One note for everyone. A six degree tilt is gentle, but it changes how you sleep, and sleep is the actual training aid here. If tilting the bed wrecks your sleep, you have traded a small blood gain for a large recovery loss. That is a bad deal. Protect the sleep first.

*Lundby and colleagues. Erythropoiesis is regulated by changes in posture. Acta Physiologica, 2026. doi:10.1111/apha.70248. Nine healthy men, six-degree head-up sleeping versus flat, five weeks each in a randomised crossover. From the group at the University of Southern Denmark, University of Copenhagen and the Medical University of Bialystok.*

## On my mind: Sometimes the job is just to say no

A big part of coaching is not writing sessions. It is saying no.

No, that race does not belong in your calendar. No, we are not adding a fourth hard day because a stranger on the internet does five. No, you should not chase that Strava segment on your recovery ride. No, this is not the block to also start running. The plan is often less about what goes in and more about what I keep out.

Derek Sivers has a line I keep coming back to. If it is not a clear yes, it is a no. When something is only a maybe, only a sort-of, only a because-everyone-else-is, the honest answer is no. A calendar full of maybes is how people end up busy, tired, and going nowhere in particular.

Here is the part that took me years to properly respect. The worst outcome is not the no. It is the wrong yes. The wrong yes looks like progress. You added the race, added the block, added the goal, and it all feels like commitment and ambition. Then eight weeks later you are flat, slightly injured, underslept, and no closer to the thing that actually mattered, because the wrong yes quietly ate the time and the freshness the right thing needed. A no costs you a moment of disappointment. A wrong yes costs you a season.

The same is true the other way. A wrong no, turning down the thing you should have said yes to out of fear or habit or a crowded calendar, will cost you just as much. So the skill is not saying no to everything. It is telling the clear yes and the clear no apart from the great soggy middle of maybes, and then having the nerve to act on it.

That is a lot of what you are paying a coach for, honestly. Not the intervals. The nerve to look at your enthusiasm, your fear of missing out, your ambitious calendar, and say, that one is a yes, and all the rest of these are a no, and here is why. Enthusiasm is easy. Judgement is the hard part.

So this week, look at your own list. The races, the goals, the shoulds. Be strict about it. Which ones are a clear yes? Everything else is a no. Not a maybe. A no. You will get more out of three things you fully commit to than ten things you half-commit to, and you already know that, because you have lived the other version.

Damian