This heavy sensation that you are describing may be related to water retention. Consumption of salty foods or salt could cause the body to retain intra-cellular water. Renin, "a chemical an enzyme secreted by and stored in the kidneys that promotes the production of the protein angiotensin." Renin-->Aldosterone = "an enzyme secreted by and stored in the kidneys that promotes the production of the protein angiotensin." Angiotensin, which causes vasoconstriction of arterial blood vessels in the body, resulting in hypertension, AKA high blood pressure, and Angiotensin II salt retention, which result in swelling in the extremities. Next, the heavy sensation that you are feeling in your legs may be associated with intermittent claudication ca be spasms or cramping pain (or heaviness, or fullness sensations felt in the feet and legs on walking or exercises that is relieved on rest, and elevation of the feet above the level of the hips or heart). The online definition of intermittent claudication = "a condition in which cramping pain in the leg is induced by exercise, typically caused by obstruction of the arteries."
I don't know of any exercises that you could do to help the pain in your legs during your periods. However, wearing some over-the-counter support hoses or compression socks below the knees ("below the knee" means at the patella bone of the legs is where the hoses or socks come up to) may help with the swelling in the feet and legs. But these compression hoses or socks are not recommended for any person who has congestive heart failure, or who has an ankle-arm index value below 0.50. Therefore, the congestive heart failure and the ankle-arm index can be diagnosed by the your primary care physician or provider. Online definition congestive heart failure: "Congestive heart failure symptoms is a heart condition that causes symptoms of shortness of breath, weakness, fatigue, and swelling of the legs, ankles, and feet. There are four stages of the disease. Treatments options include diet, medication, exercise, and weight loss." In closing, please schedule an appointment with your primary care provider or physician to make sure that your heart and kidneys are working properly.