First impressions

Just did the TB series today for the first time, right after F1a workout. Didn't really go well 

First, the supine shoulder extension walks completely fried my forearms. After 5 reps they simply refused to move anymore.

Then, later, the toracic bridges went even worse. For the first one, I had problems pushing myself up to straight hands (thanks, HBP and Se10&11). In the end, I managed to get myself to right position, but the later ones went even worse, thanks to tired shoulders.

So, in future maybe I should just do the TB series after Hs day, so that maybe there's still some kick left in my shoulders and traps.

Would it be ok to continue training the thoracic bridges other day this week, since I couldn't complete them properly/at all? I would like to get a better feel with them for the next weeks real session

No, once a week is sufficient. You did what you were capable of; now allow the body to recover. Next week see if you can get deeper into the series.

Yours in Fitness,

Coach Sommer

Coach Sommer said:

No, once a week is sufficient. You did what you were capable of; now allow the body to recover. Next week see if you can get deeper into the series.

Yours in Fitness,

Coach Sommer

Would there be an issue with doing the series twice a week Coach? Did it for the first time today. Very poor at a lot of it, but feel I need to get exposure to these stretches to start moving forward with my tight shoulders and T spine. Obviously I'll go by feel, but if I did feel ok midweek, would there be an issue with doing it more frequently?

Once a week is enough. If your are concurrently working with Foundations the iM will be enough to retain  your weekly Stretch gains and allow ample recovery time.

In the case of the Thoracic Bridge series let the understanding of why Coach calls it Thoracic Bridge inform your FL iM work as you progress.