Soreness below the calf belly, the most common causes are as follows: 1, calf muscle strain: such as frequent sports, weight-bearing activities, such as going up and down the stairs, mountaineering, hiking, backpacks, long-distance walking, etc., will cause the calf gastrocnemius muscle muscle to withstand a greater load, there will be a muscle strain, lactic acid will be accumulated in the calf gastrocnemius muscle, so there will be a soreness in the calf muscle, the calf pain will be especially pronounced at night. 2, calcium deficiency: calcium ions can inhibit the excitability of the neuromuscular junction, when the lack of calcium, neuromuscular excitability increases, often cause spasmodic pain in the calf, can be at night cramps in the calf belly, this situation must be an early detection of blood calcium, and active calcium treatment.