Muscle knots in the large, superficial calf muscle, the Gastrocnemius, are located just below the knee. These muscle knots can send a deep, aching pain to the back of the knee, making it difficult to straighten the leg fully. They can also create sensations of pain down the back of the lower leg to the Achilles Tendon, sharp pain in the heel, and a persistent ache in the bottom of the foot, often mistaken for other conditions. This referred pain pattern can be exceptionally bothersome during walking or running and may even cause intense, involuntary muscle cramps.