The science behind increasing running endurance

The beauty of running lies in its simplicity and freedom. However, bringing your performance to the next level requires breaking old habits and introducing components of purposeful training to challenge your body to “step-it-up” a level ready for race day. With a few simple, guiding principles for each training session (discussed below) you can bring focus and understanding to helping make your endurance goals a reality. To start with, it’s important to understand the two fundamental concepts of training.

1. Continuous overload

The body has a tremendous ability to meet and match with external stimuli, such as a training effort. Over time, the body’s performance will adapt to a constant level of training; and if that level remains the same, so too will the benefits of the training. Increasing the challenge of a session by modulating intensity and time effort means that the body has new challenges to adjust to and in turn, results in more gains.

The take-away: avoid stagnation by changing trainings both by intensity and load, and also type of training. // Use it: enrich your training program with new challenges like interval sessions and strength training, e.g. go to the track to run interval loops or find a hill to do jumps or sprints.

2. Recovery

It’s important to understand that the training itself only serves as the stimulus signaling the body to get stronger and further develop its endurance performance. However, when performance development takes place is actually during the recovery phase. By providing your body with enough time to recover, and with balanced nutrition, you allow the body to “digest” the training challenges and get stronger. Incorporating the right amount of recovery time and rest into your training plan will not only make you faster but is also critical to avoid overtraining and injuries. Think of it as getting better while resting.

The take-away: your performance development is taking place during your recovery phase. It is important to not interrupt this phase before you have had a chance to fully benefit (recover) from the hard training you invested into. // Use it: enjoy your rest days! Hard interval training should be exercised with caution: give yourself enough of time to recover in-between sessions. As a rule of thumb, hard trainings should only be carried out every third day.

How to increase running endurance

Now that we know the fundamentals, let’s have a closer look at the performance model and its benefits on your training.

1. Maximal oxidative effect (VO2max)

This is the maximal level at which the body can perform when relying on the aerobic energy system. This performance is largely dependent on the heart’s blood pumping capacity and can be trained like a skeletal muscle by high efforts over several sets (sets in the gym; intervals in endurance sport). Much scientific evidence exists showing that high-intensity interval training (HIIT) is a more efficient way of training VO2max than other forms of training, such as long-slow distances (LSD) or lactic threshold training (LT). Popular examples of HIIT are high effort intervals over few minutes repeated 4-6 times, or shorter 15-30s sprint intervals repeated several times (10x or more).

Use it: include an interval session regularly in your exercise e.g. a track running session doing 4x400m intervals at high but consistent intensity various times a week.

2. Lactic acid threshold (LT)

The Lactic acid threshold is the level of the maximal oxidative effect that the athlete can maintain sustainably over a longer time, such as a race. LT can be looked at as the range of the VO2max that can be utilised throughout a race without reducing speed.

It is generally accepted that LT is trained by longer, slower efforts, so-called “long-slow distance” training (LSD). LSD is typically carried out at 60-75% of your VO2max (roughly your heart rate max). Elite endurance athletes typically spend 75% of the time trained in LSD. Reason for this is that it is a gentle form of training that can be repeated after much shorter recovery than interval training. It can also well be combined with exercising different sports, also at higher intensities.

Recent research points to that HIIT also results in improvements of LT; and as such, this type of interval training develops both components of the performance model (VO2max and LT). In addition HIIT is time efficient. Therefore, HIIT should make up a greater part of the amateur’s endurance training program.

Use it: ensure that you differentiate between different training sessions and their different goals. If you do intervals, go hard (perceived effort - high to very high) and if you train long distance go slow (perceived effort - easy to moderate).

3. Work economy

The last component of the endurance model is work economy, which is the energy cost of the work carried out, or technical efficiency in a sport. The energy cost is dependent on the discipline practiced, eg. trail running costs more energy than track running. However, work economy can also be improved by purposeful training such as running drills or developed skill over time.

Use it: to improve work economy focus on technique at the beginning of your endurance session by doing running drills or practicing swimming techniques etc.

Use it all (summary)

a. Don’t get stuck in habits: raise the bar by including variety, set challenges, and a good mix of training modulation.

b. Don’t underestimate the power of recovery!

c. HIIT sessions train more components of your endurance performance and are time efficient.

d. Work on technique by including drills.

In the end, aside from the science, it's important to remember training should be joyful and give you energy. Like the great author and running enthusiast Haruki Murakami says: