The optimal running plan consists of a variety of sessions. Each run will vary in volume and intensity, some will consist of intervals with hard efforts and static rests whilst others will have a jog recovery and then we have the long sessions which are tough but more sustainable. By tapping into a variety of sessions, we are getting our body used to running at different intensities for different durations, which helps us build our overall fitness.

Threshold is a scientific term that refers to our ability to tolerate the build up of lactate during exercise. When we run, our body produces lactic acid, and it tries to clear this out whilst we are on the move. A build up of lactic acid causes discomfort and will eventually slow our run down. If you are well trained, your body is able to create and clear out the lactate at the same rate whilst you are running steadily. During these runs, you will not reach your lactate threshold. However, if you up the pace and start to run fast, you will get closer to this threshold and eventually past it. In a nutshell, the faster we run, the closer or more likely we are to hit our lactate threshold. Thresholds are individual; it is specific to you and your current level of fitness. Like running fitness, we can improve our lactate threshold, so we are able to run faster for longer. We do this using threshold and tempo sessions.

The most accurate way to calculate your thresholds is by doing a laboratory test. This is not a convenient or practical option for most people so other options include:

Threshold training involves training at or just under your current threshold level. This helps train your body to become more efficient at clearing lactate. Threshold sessions will usually include shorter intervals with periods of recovery. This allows us to run at a harder effort (faster pace) with short breaks to help stop the build up of lactate.

This is where the confusion between tempo and threshold arises. Tempo pace is closer to your threshold pace. It is the more sustainable pace that we mentioned above. It targets your aerobic base, therefore helping us improve our endurance. Tempo sessions involve longer reps. More common if you are training for a half marathon or longer, but they still have an important part to play for all distances.

To keep things clear, we have two types of sessions in your Runna plan. Intervals (we could call these threshold runs) and tempo runs (your threshold pace).

Intervals: during these sessions you will spend time above your 'sustainable' pace (i.e. your lactate threshold). It forces your body to adapt and become more comfortable running at these higher speeds.

Tempo: during these sessions you will spend longer periods of time running at a more sustainable but still a challenging pace. These workouts are key to condition the body to become faster over the longer distances. The effort will typically be between half marathon and 10k pace, but like any run, your pace might vary day to day! Your pace will also vary depending on the length of the rep. For example, you are going to run faster doing 3x 2k reps than you would over 1x 6k effort. The key note is that for both of these workouts, you shouldn't be going flat out but keeping it to 70-80% effort. If you go too quick, you will be closer to your lactate threshold (save that for your intervals!).