Heaviness in the arms and legs are symptoms of peripheral neuropathy, according to The Neuropathy Association. Onset of peripheral neuropathy symptoms can occur suddenly or over a period of several years.
Peripheral neuropathy can affect the sensory nerves, the autonomic nerves or the motor nerves. Some kinds of peripheral neuropathy affect one or two of these, while many affect all three. Heaviness in the legs is due to damaged motor nerves, according to the Neuropathy Association. Other leg symptoms include muscle cramps and difficulty with walking or running. People with peripheral neuropathy frequently drop what they are holding and have difficulty with opening jars, turning doorknobs, carrying groceries and other everyday tasks.