Do you find your muscles in legs and/or feet cramping up? Cramping happens often, especially when first starting exercise. Basically, cramping is a fatigue of the muscle, either physically or physiologically - when you are asking your muscles to do something they are not used to, even when you stand too long, walk too far, walk/wear the same shoes for too long, do some exercise it is not used to....thus the toes cramp when you start exercising.
To help the cramps, stay hydrated, ease into your workouts, and keep the body supplied with the minerals and elements it needs, such as natural supplements like bananas and other foods. Eventually the feet and legs get stronger and the cramps will be reduced. Don't forget to skip the coffee or tea before a workout. They can dehydrate the body. Also, try a cup of tonic water with quinine. Or, try mustard. Amazingly, they work!