Numbness and tingling are concerning symptoms. I would recommend that you discuss this with your doctor
for a further evaluation. While likely a minor problem, a few more sinister causes of these symptoms should be ruled out.
Numbness and tingling normally indicate irritation of the nerves that supply that area of the skin. Irritation of the nerves is broadly known as neuropathy.
The most common cause of neuropathy, especially that associated with exercise, is a compression or direct inflammation of the nerve. What is likely happening is that your foot is receiving and unusual amount of stress with this workout. This is often due to inadequate foot support (bad shoes). This causes inflammation which causes the pain. Your doctor can evaluate this and recommend shoe inserts or more supportive shoes or even a foot specialist
There are more concerning causes of neuropathy which should be ruled out. One is a narrowing of the blood vessels to the feet (peripheral arterial disease). Another is a compression of the nerves at the level of the back because of back arthritis
(or spinal stenosis). There are other causes of neuropathy like nutritional deficiencies (specifically vitamin b12), low thyroid states or even infectious (syphilis or Lyme's disease).
Talk to your doctor. Good luck!