The short answer is not too often. Speed LacesTriathletes are the main group of runners who use elastic laces as this enables them to pull their runners on quickly in transition during races. Whilst elastic laces provide an easy and quick way to pull on your pair of shoes, you should avoid the temptation to run with them in all the time.
Normal laces are designed to hold the foot firmly within the shoe and limit any forward/backward, up and down and side-to-side movement of the foot. This type of movement within a shoe can cause problems such as blistering, damage to the toes and nails and overuse of the muscles around the lower leg and foot. Provided you have a properly fitting shoe (read this!) your foot should not move excessively within the shoe and should compliment the way you run. Elastic laces can allow too much movement of the foot during foot contact phase and toe off phase that can place foot structures under stress. We have many muscles, ligaments and joints in our foot that are required to activate to stabilise our foot during running. Elastic laces can increase the instability of the foot and therefore cause these structures to work harder to maintain the normal function of the foot. This can place them outside their optimal stress range and an injury can result.
I recommend you only use your elastic laces for racing and not training. Generally there is simply no need to have elastic laces in during training and the slightly longer time spent tying them properly will reduce your risk of injury!
Andrew Maitland is a sports podiatrist at Melbourne Podiatry Clinic. Having worked closely with many elite and amateur runners over the years he has helped many people in the prevention and treatment of running injuries.