What Powers Your Sprint?
Your body has three energy systems that power movement. These are the oxidative, glycolytic, and ATP-Pcr systems, each of which serves a unique role in fueling your sprint performance . All three systems contribute to supporting energy requirements, but their relative contributions change with the duration and intensity of your efforts.
The oxidative system contributes heavily to almost all types of endurance exercise. It works slowly, but is extremely efficient at supplying ATP (gives energy) to cells in demand. It always contributes, even while sprinting, but it is the main contributor during longer efforts or submaximal efforts.
The contribution of the oxidative system during a true, single, short sprint is small (<30 sec) , but the oxidative system plays a crucial role in the parts of a race leading up to the sprint where repeated hard efforts are occurring [3, 4].
The oxidative system is involved in continued power production throughout the length of your sprint . Since the intensity in the minutes leading into sprint finishes is typically high, the importance of having a well-developed oxidative system to deliver you to the finish cannot be over-stressed .
The glycolytic system acts as a supplier of ATP when the body needs it fast. It relies solely on carbohydrates as fuel source with very few steps to break them down, which allows it to work faster than the more sustainable oxidative system. The reliance on the glycolytic system during a maximal sprint is very high, especially if the sprint lasts longer than a few seconds . It is contributing at all times, but glycoltytic production peaks with maximal efforts that are in 5-75 sec range . This means that it is key in meeting the demands of high intensity portions of a race, as well as the sprint itself.
The ATP-Pcr system is the fastest supplier of ATP to cells in need. Its ability to work extremely fast makes it the primary contributor during a short, maximal effort, like a sprint. The extremely rapid regeneration of ATP from the ATP-Pcr system doesn’t last long; its contribution begins to fade after just a few seconds . This system is able to make ATP faster than the others, however, it is also the least sustainable.
Application to Training
Understanding the energy systems is key in training your sprint performance. Determining which systems to target and designing high intensity workouts that challenge these systems properly is key in improving your sprint at the end of a race [7, 8]. Although they will also train your oxidative system, targeting shorter maximal efforts and sprints with adequate recovery time will train your glycolytic and ATP-Pcr systems.
The graph below shows the energy system contributions of cyclists who regularly perform sprint training, compared to triathletes who do not during a 90-sec all-out effort. The sprint trained cyclists have a significantly greater glycolytic and ATP – Pcr contributions to support their high peak power.
Other Side of the Coin
What exactly are the energy systems providing energy to? In one of my graduate exercise physiology classes at Sacramento State, professor Dr. Daryl Parker opens by asking the class, “How long can we sustain a sprint if we rely only on the ATP stored in the muscle?” After a great amount of deliberating among eager grad students, answers like “8 seconds”, and “1 minute” were thrown out. After some time, Parker replies with “about one second”. It turns out that after that one second, it is now the job of the ATP-Pcr, glycolytic, and oxidative systems to defend the muscle’s energy state while you continue ripping on the bars and smashing on the pedals.
The energy systems sustain a percentage of the muscles maximal contraction capability with each ongoing contraction. Is there potentially a limitation to your sprint power in your muscles’ maximal contraction abilities, just like the energy systems that power its ongoing contractions? What determines the ceiling for the muscle?
The maximal contraction force and velocity produced by your muscles is a limiter to your power production. The ability to generate both high force and velocity (power) is influenced by physical characteristics in the muscle itself, and by the effectiveness of the nervous system in controlling the muscle [9, 10].
Training the Nervous System and Muscles
Since there is a very strong relationship between maximal strength and maximal power production, another way to improve your sprint performance is to train the contractile, structural, and neuromuscular components of the muscle .
We won’t dive into the idea of muscle fiber typing (fast twitch vs. slow twitch), as regardless of fiber type, peak power is trainable. This doesn’t mean that you can be a world class sprinter, but you can improve. It has been shown that through many different types of strength training like explosive plyometric exercises and heavy weight training, sprint power output can be increased [10-17]. This increase in power, which is the product of force and velocity, is thought to generally be a function of increases in maximal force production, which outweigh potential decreases in peak velocity with such training .
Although strength training leads to muscle remodeling and hypertrophy, a large portion of this improvement is thought to occur through neural and structural adaptations, since increases in muscle cross sectional area are minimal while performing concurrent endurance training [15, 18-20]. When performed in certain ways, methods for “strength training” on your bike, such as low-cadence/maximal sprints have been shown to increase power as well, but may hinder power production at higher cadences . It might make more sense to strengthen the musculature involved in sprinting without providing an opportunity to alter the coordination pattern of your sprint.
As we will discuss in the next section, peak power is very specific, where peak force production (strength) is applicable across a wide range of movements. Increases in strength provide the necessary means for high power output, and strength becomes power when delivered properly.
Think back to the first time that you tried sprinting. Did you cut your knees on your stem bolts? Do you still cut your knees on your stem bolts? Did you weave side to side? Over-geared…. Under-geared? Sprinting on your bike is a very complex movement pattern since it requires maximal power output and coordination from the legs as well as the upper body .
In complex movements requiring high power output like Olympic weightlifting exercises, it has been shown that familiarization with the movement plays a key role in power production [22, 23]. Proper inter-coordination of muscles, controlled by the nervous system, allows you to generate and deliver power efficiently. Since power production – not just from each individual muscle, but synergistically in a given context (like a sprint) is very important, coordination is another potential area of improvement for your sprint [9, 24].
Practicing your sprint form often can lead to beneficial changes in the nervous system as you continue to become more familiar with the complex movement pattern of sprinting at higher cadences/power outputs [25, 26]. This means that when the time comes at the end of a race, throwing down a well-coordinated sprint is second nature. Don’t just wait until a group ride, race finish, or sprint workout to practice your sprint form. Try tossing some short practice sprints into more of your workouts.
One way to improve coordination is to develop the ability to sprint out of the saddle at higher cadences. There is evidence showing that as power output increases, higher cadences provide better muscle activation, making the higher cadences optimal .
Certainly, there are limits here, since sprinting at 200 rpm may not necessarily mean more power production. There seems to be an apex around 120-130 rpm, where the balance between optimal muscle activation and boundaries of the force-velocity relationship meet [21, 28].
Sprinting at these high cadences enables a rider to achieve better peak power for the first few seconds, but the rate of fatigue during a prolonged sprint is greater . This means that as sprints get longer, you may want to grab a gear or two to adopt a slightly lower cadence over time. Try a couple of short sprint efforts on your next ride and look at your cadence when you upload it. While 120-130 rpm may not be the best for you, if you are sprinting at 75-80 rpm by default, you can probably improve through practice.
How much time and effort should you spend working on your sprint? Do you reach the end of a race fresh, or are you in trouble from the whistle?
If just being in the group is challenging your abilities, you may spend more time focusing on training your endurance than your sprint form. A valid argument can be made that utilizing sprint interval training is a great way to improve your endurance, so it may be possible to develop these abilities concurrently to some extent. In the case of being a rider who is suffering from the gun, spending a large portion of your training time working on your sprint coordination and cadence may not make sense until you have the means to deliver it.
- Design a well-balanced training program that incorporates development of all energy systems. Don’t overlook the importance of shorter, high-intensity efforts in cycling performance.
- Consider incorporating strength and neuromuscular power training into your program.
- Do not wait until a group ride, race, or sprint workout to practice your sprint. Incorporate short practice sprints into more of your rides to enhance coordination.
- Consider the potential trade-off involved in spending a large portion of your time training your sprint.
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