Studies show that the quality of sperm, measured in concentration of sperm and sperm count, is declining in Western countries, with some suggesting a drop of up to 38% in concentration. Numerous factors could explain the trend, from lower levels of physical activity to exposure to environmental chemicals. But the downward dip in sperm quality matches up with increased TV viewing, so researchers from the Harvard School of Public Health (HSPH) decided to investigate the relationship between TV viewing, physical activity and semen quality.
The scientists analyzed the semen quality of 189 relatively healthy New York men aged 18 to 22, who were asked about how often and how intensely they exercised, as well as the amount of time they spent watching TV, videos or DVDs. The men were all normal weight and height, and the majority did not smoke.