Over the past couple of weeks, I've been getting a numbness / slight cramp in my toes when exercising. I normally exercise for 2 to 3 hours every morning. I do circuit training, using a cross trainer, and lift weights, and also have an exercise bike. I follow this with aerobics and yoga. I usually get the numbness when I do the yoga. I'm 61, have one kidney, and have conjoined toes (2nd and 3rd toes), on my feet. It is these toes that get numbest. I do not take any medication.
Any thoughts / help appreciated.

I have kidney problems and have numbness in my feet. Maybe you should go check out the oneyou have.

I also have problems with muscle tension in my back. I don't know which one is causing it.

OK thank you, I will.

Get checked out for diabetes urgently please. Numbness usually starts in the left foot, with second and third toes first.

I remember suffering from 'cold' feet and toe numbness about 5 years ago.

May have had something to do with the 35 day walk (pilgrimage) I did averaging 30 km a day across from the French Pyrenese, past Santiago de Compostela to finish at Cape Finisterre.

You are possibly 'pounding' your feet too much! (I was 56 at the time).

As it only happens during exercise, it is likely that something you are doing is compressing either a nerve or a blood vessel supplying the area, and simply not doing it, or doing it for a shorter period, will avoid it. or you could just ignore it, assuming the numbness is very brief.

But I agree that if you haven't had a physical check up in say the past year, it would be wise. At your age should have yearly checks of, at minimum, fasting glucose, lipids (HDL & LDL cholesterol and triglycerides), creatnine and uric acid, manual prostate exam, and an exercise stress test every couple of years (more often if abnormal or borderline results). PSA is controversial but personally I'd include it especially if the prostate is enlarged which at 61 is likely. It is not an absolute indicator but having a baseline and then tracking it can help distinguish between likely benign prostate enlargement and a fast growing cancer.

so, your getting numbness only in the conjoined digits? or both feet or ?

stop the bike and the yoga for a while, try some ice and or heat , assuming your temp sense is intact

https://en.wikipedia.org/wiki/Dermatome_(anatomy)