Factors that affect sperm volume can include use of drugs and cigarettes, certain physical activities, and emotional stress. These factors tend to be temporary and, once removed, sperm count can typically be increased. Men can purchase self tests at home to determine the amount of sperm present in a sample of semen, or can be tested at a doctor's office.
The source of sperm is the secretion of multiple glands found throughout the male reproductive system. It typically leaves the body through the urethra of the penis during ejaculation. The World Health Organization (WHO) defines a healthy or normal sperm count as between 20 and 40 million sperm per milliliter of semen. The average volume of semen produced should range between 2 and 5 milliliters.
Qualifications are also placed on the type of sperm produced in a normal sample. These factors can affect the likelihood of a successful conception in couples dealing with fertility complications. The majority of the sperm should be alive, though it is expected for some to be dead. One third should be normally shaped and swimming rapidly. Over half of the sperm should be swimming forward.
The use of drugs can have a negative impact on sperm volume. Marijuana and cocaine have both been proven in different scientific studies to reduce the amount of sperm present in semen temporarily by up to 50%. Use of marijuana can also impair the functionality of the remaining sperm, causing them to swim slower and inhibiting them from penetrating the egg. Smoking traditional cigarettes causes similar results, reducing sperm count and limiting their motility.
Sperm volume can also be affected by certain physical activities. Overheating the male reproductive regions, such as might happen for those involved in outdoor construction, or can occur in a sauna and hot tub, can reduce the amount of sperm present in a sample. Riding a bicycle also has a proven correlation with lowered sperm count and altered sexual performance. Doctors believe this may occur as a result of the bicycle seat pressing on certain blood vessels and nerve endings that are vital for peak numbers of sperm present in semen.
Various health and genetic factors that can lower sperm volume include major illnesses and deformities in the reproductive organs. Cancer typically requires exposure of the patient to chemo therapy and radiation, both of which can have devastating long term affects on sperm count. The count often rebounds, however, several years following the completion of any treatment regimens. Malformations in the testicles or vas deferens can also negatively affect the presence of sperm or semen in the body.
Some physicians speculate that emotional health can have an impact on sperm volume. Feelings of stress at work or at home can have a temporary affect on an individual's sperm count. These factors tend to be temporary, however, and sperm numbers can increase when stress is reduced.