These measurements are impossible to obtain with manual analysis, providing deeper insights into sperm function and fertility potential
The actual distance traveled by the sperm head along its curvilinear path per unit time. Measured in µm/s. Indicates sperm vigor and available energy reserves. Higher values suggest more energetic sperm.
The straight-line distance between the first and last points of the track divided by total time. Measured in µm/s. Reflects the net forward progression - how efficiently sperm swim toward their target.
The distance traveled along the average (smoothed) path per unit time. Measured in µm/s. Represents overall swimming capability by averaging out minor path deviations.
Calculated as VSL/VCL × 100. Expressed as a percentage. Indicates path efficiency and is associated with hyperactivation status. Lower linearity may indicate hyperactivated sperm.
Calculated as VSL/VAP × 100. Expressed as a percentage. Measures the departure of the average path from a straight line. Higher values indicate more direct forward progression.
Calculated as VAP/VCL × 100. Expressed as a percentage. Measures oscillation of the actual path about the average path. Indicates the degree of side-to-side movement during swimming.
The magnitude of lateral displacement of the sperm head about its average path. Measured in µm. A key indicator of flagellar vigor and hyperactivation status.
The frequency at which the sperm head crosses the average path. Measured in Hz. Reflects the tail beat frequency and overall flagellar function.
The average angle of direction change between successive frames. Measured in degrees. Higher values indicate more erratic movement patterns.
These kinematic parameters provide objective measures of sperm function that are impossible to assess with traditional manual analysis. The combination of these measurements helps clinicians and researchers understand:
Even the most experienced operator studying motile sperm using microscopy cannot avoid focusing on a moving object. Moreover, studying the field for several minutes means many motile sperm will have entered and left the field of view. This leaves only the non-progressive fraction enumerated with any accuracy, leading to over-counting of motile sperm - especially in samples with higher density and vigorous movement.
The current WHO recommendation of reporting only 3 grades of motility offers only the percentage of sperm swimming forward but not how well they swim. This significantly reduces the measurement's clinical value. SAMi's kinematic parameters restore this clinical utility by providing objective, quantifiable measures of swimming quality.
