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Blocked Legs - What's that all about?

The intentions were good. You took two days off the bike following a hard training block or back-to-back races and were expecting the rewards to flood in!

You hit send from the cockpit to the engine room and the reply was

'Computer say's NO!'

Your legs are screaming one minute into your ten minute effort, your heart rate is through the roof, and you are breathing is like something you would expect at altitude.

' legs are blocked! BLOCKED!'

It's one of the niche words that only cyclists tend to know, yet never fully understand why it occurs or how to overcome it best.

Over this blog I'll talk about what causes this feeling and how you can overcome it.



Of the two issues we are addressing here, this is without doubt the less straightforward of the two. Of the available research out there, it appears the issue is primarily linked to *blood viscosity, and more specifically plasma volume, which decreases (up to 12% in seven days) following periods of low/inactivity. This is significant, and the effects will be profound, given plasma makes up 55% of your blood’s total volume.

Secondly, exercise also assists in opening and expanding your smaller arterial pathways. Hence, when you take some time off the bike, these pathways essentially shrink, further limiting blood flow to the muscle, with the subsequent knock-on effect being is the reduction in available red blood cells, and therefore oxygen, available in the muscle.

This is also a consequential effect of the aforementioned increase in blood viscosity, and in turn results in a reduction of your body’s ability to break down glucose into Adenosine Triphosphate (commonly referred to as ATP), the primary role of oxygen in the muscle.

So, in layman’s terms, when we take time off, our blood becomes thicker, and our heart has to work harder to pump that blood around our body. This is compounded by the fact that the pathways to transport the now thicker blood, are narrower. Combined, the net result is an increased input (Heart Rate), for a given output (Power)- we have to work harder to sustain the same effort.

Sound familiar?

Thankfully, it is not all bad. Although a reduction in plasma volume is one of the first adaptations to occur following a period of time off the bike, it is also the first to rectify itself and increase again when exercise is resumed. This would go some way to explaining why there is often a stark contrast between how you feel for the first hour or so of your ride, following even one rest day, and towards the end of the session or race as it progresses. This leads us on to the second part of the article.

How do you ensure that such issues do not hamper your performance come race day?


The solution, you'll be glad to know, is much more straightforward than the root cause. The general consensus would suggest that, prior to a race, it is best that one takes the day, two days prior to their event, off, with a pre-race ride on the day prior to the event itself. The reasons mentioned above are why this is the case. If done right, you will benefit from both an enhanced state of recovery following the rest day, while also not getting that ‘blocked’ feeling in your legs for the first hour or two of the event itself, especially if the start is going to be hard and you will be required to be at your best from the get-go.

As far as a pre-race ride goes, I have found it to be quite an individualistic topic, with certain riders preferring a different style of session. Some advocate a shorter but more intense ride (something I would prefer), others longer but less intense, some just plain hard!

And really, it matters little. What you are essentially trying to achieve here, is preventing the issues and subsequent problems described in the first part of this article. If it achieves that, then it has done it’s job. It is even possible to vary your pre-race ride, event dependent. If you know that freshness is the priority for your event, in the case of something such an Ultra Endurance race for example, then you can do a lower dosage training session the day prior, as you will have time to ‘ride into’ the event so to speak.

Likewise, if the event is short, such as a TT, and you know you need to be on your game from the off, you can add a little more intensity or volume, increasing the dosage, to ensure this is the case. There is no one right or wrong answer here. It is what works for you.

Finally, this is also something applicable to your training sessions. If you are due to complete a high dosage training session on a Saturday for example, following a recovery/rest day on a Friday, and that you know you don’t respond well initially following a recovery day, then altering the plan in conjunction with your coach, placing the lower intensity day prior to it and swapping the two training sessions around, is an option.

This is something at Elevation Coaching we have experimented with in the past and found good results. It will enable you to get more out of the harder session, completing it as it should be and achieving the required intensity for the set intervals while achieving the same results from the easier day’s efforts at the same time. Time is a valuable currency.


Hopefully, this goes some way to addressing concerns or answering questions you may have had. The lesson: discover what suits you, and your body. Just because the same thing happens to each of us, to a certain extent at least, does not mean that the finer details of the solution will be the same, not at least if you are in search of optimised performance, which if you are reading this, I presume you are.

Do not be afraid to experiment with your training to a certain extent, if you feel something isn’t working for you, and keep trying until you find a formula that suits. In this case particularly, one size certainly does not fit all.

*You may attribute thicker blood to improved performance, but this isn’t always the case. Your performance will only be enhanced as a result of more viscous blood, when the number of red blood cells within it, and therefore it’s oxygen-carrying capabilities, increase. Volume in such a case, will not change, or may in fact increase (usually as a result of doping). When referring to the subject in the article, however, we are referring to a decrease in plasma volume, and therefore blood volume in general. Note, viscosity increases yes, but overall, and plasma volume decreases, and crucially, the number of red blood cells does not change.

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