The four grams have to be taken in single gram doses for three days with the last ingestion three hours before competition. Another little trifle is that training can lift blood phosphate levels more than supplements. If they are going to be used, calcium intake must be increased pro rata. High- calcium content foods include milk, cheese, broccoli, legumes, green leafy vegetables, nuts, seeds, peas, beans and lentils. Since milk products are often linked to allergies, it is unwise to rely on them as the main source of calcium.
Milk also lacks magnesium.
Phosphorus is, indeed, an enigma.