Video records of motility of sperm incubated in four Krebs Ringer media. These included KR0B (containing no NaHCO3), KR0B-BSA (containing no NaHCO3 but supplemented with BSA), KR4B (containing 4 mM NaHCO3) and KR25B-BSA (containing 25 mM NaHCO3 and 0.3% BSA). Video recording was performed at 1 h of incubation time. The data shown were representative of ten video clips recorded for each sample in one of the three replicate experiments performed on different days.