Implantation is the attachment of the fertilized egg (embryo) in the endometrium (uterine lining). This usually happens about a week after ovulation and fertilization.
There are few things a woman can do wrong to prevent implantation.
Strenuous exercises are unlikely to prevent implantation. Straining with bowel movements, for example, will not impact embryo implantation. Constipation is a common side effect of progesterone which slows the digestive tract and but that it would not impact implantation.
Jumping up and down or doing physical exercises are also unlikely to prevent implantation.
The only know thing that can sometimes prevent implantation is taking high doses of certain hormones, like those which are in birth control pills. Those hormones are part of "Plan B," or the morning-after pill.