Some of Garmin's Fitness devices offer the choice of Smart Recording or Every Second Recording.
Smart Recording records key points where the fitness device changes direction, speed, heart rate or elevation. This recording type allows the user extended recording time given that it is recording less track points, thus taking up less memory.
Every Second Recording records the activities information every second no matter if the device changes direction, speed, heart rate or elevation. This recording type provides a more defined track log of your activity. However, recording time will be reduced given that it taking up more memory.