Our second question comes from Arnaud, a runner in his mid 40’s from Singapore who has been running over 10 years. He runs between 100 and 120km per week, 6 days a week.
” Are there any benefits to sprinting for Long distance runners (say 8×60-80m once a week) ? Is it worth it (Risk of injury, other workouts etc)? “
Let’s first go over what’s going on when sprinting from a physiological and metabolical standpoint.
Metabolic and Physiologic demand
Most people classify running in two categories, Anaerobic (sprinting) and Aerobic (anything above 400m). But in reality such a dichotomy is not true. The energy demand work as a spectrum, which can be divided in three main pathways:
- The Phosphocreatine Pathway
- The Glycolysis pathway
- The Aerobic Pathway
The Phosphocreatine route happens during very short bouts of effort of 10 seconds or less. You’ve heard of creatine? Well this the energy that is always available in our system allowing us to sprint at any given time. This pathway is extremely short-lived, it allows us to make an sudden explosive burst of energy, and it’s main use, from an ancestral point of view, was to allow us to escape and flee immediate danger that presented to us (like suddenly being chased by a tiger, that would allow us to sprint to the nearest tree and climb on it). This energy system is purely anaerobic, it does not use oxygen.
The Glycolisys pathway uses the readily available blood glucose and last for about one minute. It is an anaerobic system that generates lots of wastes (Hydrogen ions, lactic acids among others)
Then the Aerobic pathway is what, as endurance athletes we rely on 99% of the time, the conversion of oxygen into ATP (energy)
All of the above occur as a spectrum. This explain why each time you do a track session, the first 50 ~ 100m feel “easy”, and you tend to go very fast effortlessly. When a group of runners do 1000s on the track, the first 100m usually go extremely fast and feel much easier than the next 100m and so on. This is because we use (and sometimes deplete) our reserve of free energy, the phosphocreatine pathway, which explains why Creatine is such a popular supplements among anaerobic athletes such as sprinters, olympic lifters. It takes about 30s rest to replenish 50% of our stores and 90s or more to replenish 100%.
What all this have to do with a long distance running? Well research shows that maximal speed is extremely well correlated to endurance speed. One of the main reason is that the higher the speed the more our nervous system will be elicited. The nervous system’s role as director of speed development is independent of the energy-producing systems inside the muscle fibers. Max speed improves as the nervous system learns to coordinate muscles in ways that promote faster stride rates, shorter contact times with the ground per step and quicker generation of substantial propulsive forces. A key goal for endurance runners is to develop the ability to run more quickly while simultaneously expanding the capacity to sustain higher speed over extended periods.
Simply put, speed can be defined as:
Speed = stride rate (cadence) x stride length
The relationship is linear: improving your stride rate by x% will improve your time by x%. According to research, stride rate (cadence) is the most responsive to training. How do we increase the stride rate without changing stride length? The main factors is ground contact time and leg turnover, which are a function of neuromuscular efficiency !
To sum up:
Training at (or near) max speed ⇒ training the nervous system ⇒improve coordination and muscle fibers recruitment ⇒ shorter ground contact time ⇒ increase stride rate ⇒ increase speed.
How to train the nervous system
There are many ways, below three common methods:
- Stride drills
The definition of strides often differs from coach to coach. For me strides are running with a priority on running form: fast leg turnover (high cadence), high speed, good leg extension by using/firing the glutes and not the hamstrings. Each rep would last for about 10 to 40 seconds. With full rest and recovery between each repetition. The principal target of this exercise is the nervous system because of the coordination demand
- Hill sprint
A more demanding exercise metabolically speaking, less on coordination. This requires lots of power and is a form of strength training for runners of all distances. Each rep would last from 10 to 20 seconds followed by a full recovery.
- Explosive drills / plyometrics
Things like box jump up, box jump down, single leg skipping (with or without extra weights), hoping, rythm/speed bouncing, rope jumping etc.
Is it worth it and does it bear any risks
It is in my opinion definitely worth it. I am personally having all of my athletes do strides at least once a week and I do them once or twice a week too. Just like every exercises it has its own risk. The key, just like any form of training is to build up very slowly and gradually. Letting the body the time to adapt to the stress is the key. If you’ve never done any of this kind of drills, don’t start with 8 x 100m sprints! First of, start with strides, 3 to 4 reps of 10s each, then increase the number of reps and/or the duration very gradually over the weeks.
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