The study aimed to understand why some men have sperm with poor movement, leading to infertility. Researchers compared proteins in sperm from infertile men to those in sperm from healthy men. They found that a protein called glucose-6-phosphate isomerase (GPI) was lower in infertile sperm. GPI helps convert a type of sugar in the sperm into another form. By adding the converted sugar to infertile sperm in the lab, the researchers improved their movement. This suggests that problems with GPI and sugar conversion might be one reason for infertility due to sperm not moving well. Identifying these differences could help improve treatments for male infertility caused by poor sperm movement.