Riding flats, my legs don’t “work”

[PedalOC]

Riding flats, my legs don’t “work”

First a little about my background. 31 yr old male, and I train about 10 hours a week. I am a typical light rider and do a lot of hill work. I don’t experience problems when riding hills.
When riding flats in threshold speed I don’t manage to realize my potential. Often I experience trouble reaching 85-90% of maximum HR, and the problem is my legs. After a few minutes in the interval my left calf stops “functioning” or stiffens up. Later on my left thigh and also my right calf/thigh stops responding.
It sounds diffuse, but I can best describe it as I don’t manage to recruit more power from the muscles. Even though my HR can be as low as 80-85% when it starts.
Eating Magnesium helps a bit on the problem. Cycling in the cold may aggravate it. Starting the interval slowly may also help me reaching higher HR.
Has anyone experienced this? Is it just lack of fitness when riding flats, or some sort of muscular problem?

 

[GreasyMonkey]

Sounds like blood-flow restriction.

I had expereinced something similar in very hard efforts, particularly on my TT bike. I am no lightweight climber, but a Pave/cobbled classics & TT specialist, so it affected me in my preferred events.

Questions:
Is there any sense of numbness in your legs once the problem becomes apparent?
If you stop and get off the bike, do you experience any "pins & needles" after getting off the bike, within 1-3 minutes?

If the answers are "yes", my guess is that you may be pinching the blood vessels in your groin/crotch area, often it is the veins that are pinching (they are near the surface), restricting the blood return to the heart & lungs.

The solution? For me it was to tilt the saddle nose UP, forcing my pelvis to rotate backwards, assisted by Pilates exercises to strengthen the lower pelvic muscles.
The result was lifting the softer perineal tissue off the saddle and putting the weight back on the sit-bones, also opening up the hip joint angle (Femur - lower torso).
A benefit that comes with this opening up of the hip angle is better utilization of the hip and upper thigh muscles, getting them into a more optimal range for generating max forces and better leverage across the joint.

Hope this helps.

 

[PedalOC]

I don't experience pins and needles feeling.

But actually, my left foot often gets "cold" or numb. So I have been thinking about your suggestion, that it could be pinched veins. I also have quite visible veins, so this sound like something I need to check out. Thanks!

How much did you lift the nose of the saddle?

 

[GreasyMonkey]

I don't experience pins and needles feeling.

But actually, my left foot often gets "cold" or numb. So I have been thinking about your suggestion, that it could be pinched veins. I also have quite visible veins, so this sound like something I need to check out. Thanks!

How much did you lift the nose of the saddle?

I have it so that it is about 3-5mm higher than the back edge. It is quite visible that the saddle (Sella Italia SLR) is tilted nose-up, but not excessively so.

I experimented with it so that it was the minimum that would make it hard for me to tilt my pelvis forward (inward arched back), so the natural position was to roll back onto the sit-bones, where I should be positioned.
With the tilt change, you may find that you need to take the saddle forward by a few mm, and also raise it by 1-2mm as you will be moved rearward and slightly lower with the adjustment.

Hope you find a solution, not a nice feeling to be riding "with half a leg...."

Cheers.