What happens inside our bodies when cycling?
Let's take an example first. In the final sprint stage of the 10th stage of the Tour de France last year, with only 300 meters left from the finish line, the fast-paced team took the lead in the challenge. Sam Bennett launched the sprint with the help of the sprinter, and behind him, Sagan and Euan were not willing to be outdone and also launched an attack. However, it was too late, and Sam Bennett successfully won the championship of the stage. Although Sagan and Yoan tried their best, they were unable to "overturn" before the finish line.
Sam Bennett's championship may seem very simple, but you have to think that after cycling for 168 kilometers, there is still room for such a devastating sprint, which is not only as easy as talking about. In order to win in the end, Sam Bennett not only needs to develop meticulous tactics, but also needs to excel physiologically. Stable and strong physical strength naturally goes without saying much. If you can't even keep up with the big team, then everything is unnecessary. Sam Bennett needs to hide among a group of riders to save energy as much as possible. Finally, with the help of the entire team's scalpel, he launched a deadly attack and pocketed the victory.
So how does the energy system of a successful rider like Sam Bennett operate during cycling? Let's study it today!
The role of ATP
ATP was introduced in high school biology class, but I don't know if you still remember it. Anyway, I forgot... This high-energy phosphate compound, called adenosine triphosphate, is an important source of energy for our body. The key to Sam Bennett's victory is the mechanism of ATP biosynthesis. First of all, we humans and plants acquire energy in very different ways. Plants capture light energy through chloroplasts, while animals release chemical energy through cellular respiration. But chemical energy cannot directly drive our human body's movement, but it is necessary to make ADP (adenosine diphosphate) in human body use it, combine it with PI (organic phosphate) and other compounds (phosphoric acid, carbohydrate, fat), and generate ATP.
Under the action of ATP hydrolase, high-energy phosphate bonds far from A in ATP are hydrolyzed, releasing their energy, while also generating ADP and Pi. The energy released by ATP hydrolysis is an important source of supply for human life activities. From the muscle level of athletes, ATP constantly provides energy for the transverse bridge cycle. Through the transverse bridge cycle, the muscle filament slides to achieve muscle contraction. In essence, it is a process of transforming the chemical energy of ATP decomposition into mechanical energy through the interaction between actin and myosin. Have you started to feel dizzy when you see this? And our bodies need to constantly repeat this cycle mechanism.
1. Full speed sprint stage
Professional term: phosphocreatine system
Role in cycling: It allows you to fully exert your power for 10 to 15 seconds and is a "good helper" for drivers to make the final sprint.
Phosphate creatine is a high-energy phosphate compound stored in muscles and other excitable tissues such as the brain and nerves. Under the catalysis of creatine kinase, phosphocreatine can transfer its phosphate group to ADP molecules and convert them into ATP. Muscle cells not only have a large amount of phosphocreatine (3 to 4 times its ATP content), but also regenerate ATP quickly, making phosphocreatine play an important role in sprinting.
So the question arises, why don't we keep more ATP in the body to replace the role of phosphocreatine to create new ATP? Mark Burnley, Senior Lecturer in Exercise Physiology at the University of Kent, said, "ATP is a fairly heavy molecule. If you rely solely on ATP to support a marathon race, you will have to gain about 100 kilograms, which sounds uncomfortable. Therefore, our body also uses fat and carbohydrates as energy storage, which are lighter than ATP
The rate of ATP regeneration from phosphocreatine is very fast, and the most important thing is that it can be completed without the involvement of oxygen, without any side effects. However, although there is a large amount of phosphocreatine in the muscles, its reserves are still limited, so your sprint cannot last for too long. Our intelligent bodies have long thought of this. When the breakdown of phosphocreatine in the body is similar, you will not immediately "fall out" due to insufficient energy, but will be taken over by other energy mechanisms in the body to generate ATP.
Simply put, this phosphocreatine system is very active. It can not only quickly and efficiently generate ATP for immediate use, but also "preemptively". When phosphocreatine begins to hydrolyze, it sends a "signal" to the mitochondria in your body, causing them to increase oxygen consumption, preparing for the handover of ATP production mechanisms in advance.
How to train this system
Firstly, we should note that the phosphocreatine system itself cannot function independently, but rather operates in conjunction with other energy generation mechanisms. The best way to enhance this phosphocreatine system is through sprint training. If you want to increase your power output during sprints, you need to increase the rest time between each round of sprint training. However, if you want to use sprint training to improve your aerobic capacity, you need to shorten your rest and recovery time for each round of sprints.
2. Breakthrough stage from the collective
Professional term: Glycolysis system
Role in cycling: It allows you to consistently output maximum power for 90 to 120 seconds, commonly used by riders to break through from large groups
The glycolytic system is another energy mechanism for the biosynthesis of ATP, unlike the synthesis of phosphocreatine, which relies on glucose or glycogen stored in muscles and liver to synthesize ATP. Although this process can be carried out without oxygen, this system can still be seen as the first stage of the body's aerobic system operation. Similar to phosphocreatine, the advantage of the glycolytic system is that it does not utilize oxygen to quickly provide energy, which is more important for muscle contraction, but can only support a very short period of time. This system can generate approximately 100 times the energy of a regular aerobic system.
Once again, these different energy mechanism systems do not work independently, and their 'work handover' is also very natural. Cycling coach and exercise physiologist James Sprague said, "The aerobic, glycolytic, and phosphocreatine systems in the body work together, but their percentage of energy supply varies at each stage
Many well researched colleagues will know that the glycolytic system produces lactic acid. And lactic acid is often associated with muscle fatigue, making many car enthusiasts afraid to avoid it. In fact, this is totally a misunderstanding. Lactic acid does not cause muscle fatigue. On the contrary, our muscle cells will transfer lactic acid to the liver through the lactic acid cycle, and then gluconeogenesis will be carried out to convert glucose to re energize muscles.
You can think of the lactic acid system as a buffer, "explained Sprague. There are even signs that when we start exercising, non working muscles will transport lactic acid to the liver as fuel, leading to an increase in our blood lactate content
How to train this system
Any high-intensity power output of 30 to 90 seconds depends on this glycolysis system, such as the driver's breakthrough action in the car group. If you want to train this glycolysis system well, you must try to engage in high-intensity exercise in a short period of time. The so-called high-intensity refers to exceeding your VO2MAX (maximum oxygen uptake) by more than 90%, or you can choose to set the training intensity near the lactate threshold. Most coaches would recommend using a two-stage approach, with 80% of training programs conducted at low intensity and only 20% above the lactate threshold.
3. Endurance cycling stage
Role in cycling: allowing you to support the entire race with sufficient endurance
In addition to synthesizing ATP through phosphocreatine, glycolysis, and lactic acid, our body also transports energy to muscles through this pathway during low intensity exercise. During prolonged endurance cycling, the enzyme oxidizing nutrients (fatty acids) in mitochondria will continuously provide energy for you, but the "cost" will be higher.
Nicolas Willsmer, lecturer of physical education at Bath University, said: "oxidative phosphorylation will consume a lot of oxygen, and can produce 20 times more energy than glycolysis system. However, it will be slower to re synthesize ATP, so only when the exercise intensity is low, can oxidative phosphorylation play its role better. It is an energy supply system for any low-power long-distance exercise."
How to train this system
The best way to train this system is to run long distances at an easy pace. How do you define "easy speed"? It's 75% below your maximum running speed. At this intensity, this system can operate at its maximum ATP conversion rate. In addition, long and slow cycling activities can also cultivate your overall adaptability, such as increasing the number of capillaries. The more capillaries in your body, the more oxygen enters the cells, and your performance on the field will be even better.