What happens in your body during scientific training cycling?

What happens inside our bodies while riding?

Let's take a look at an example that happened in the final sprint stage of the 10th stage of the Tour de France last year. With only 300 meters left before the finish line, the Rapid Racing team took the lead in attacking. Sam Bennett, with the assistance of his charging hand, launched a sprint. Sagan and Euan, who were not to be outdone, also followed suit and launched an attack. However, it was too late, and Sam Bennett successfully won the stage championship. Despite Sagan and Youan's best efforts, they were unable to "overturn" before the finish line.

Sam Bennett's championship may seem very simple, but you have to think about it. After cycling for 168 kilometers, he still had the energy to launch such a devastating sprint. It's not just easy to talk about. In order to "win" in the end, Sam Bennett not only had to develop meticulous tactics, but also had to excel physiologically. Stable and strong physical strength goes without saying. If you can't even keep up with the big group, then everything is out of the question. Sam Bennett needs to hide among a group of drivers, save as much energy as possible, and finally launch a deadly attack with the precise assistance of the entire team like a surgical knife, pocketing the victory.

So how does the energy system of a successful cyclist like Sam Bennett operate while riding? Let's study it today!

The role of ATP

ATP was introduced in high school biology class, I don't know if you still remember, but I forgot... This high-energy phosphate compound called adenosine triphosphate is an important source of energy for our body, and the key to Sam Bennett's victory is the mechanism of ATP synthesis. Firstly, the ways in which humans and plants obtain energy are very different. Plants capture light energy through chloroplasts, while animals release chemical energy through cellular respiration. However, chemical energy cannot directly drive human movement. Instead, it needs to be utilized by ADP (adenosine diphosphate) in the human body, which combines with PI (organophosphates) and other compounds (phosphates, carbohydrates, fats) to generate ATP.

Under the action of ATP hydrolase, high-energy phosphate bonds in ATP that are far away from A are hydrolyzed, releasing their energy while generating ADP and Pi. The energy released by ATP hydrolysis is an important source of energy for human life activities. From the perspective of athletes' muscles, ATP continuously provides energy for the transverse bridge cycle, completing muscle filament sliding and muscle contraction through the transverse bridge cycle. Essentially, it is the process of converting the chemical energy of ATP decomposition into mechanical energy through the interaction between actin and myosin. Are you starting to feel dizzy by now? And our bodies have to constantly repeat this cycle mechanism.

1. Full speed sprint stage

Professional term: phosphocreatine system

Function in cycling races: It allows you to exert your full strength for 10 to 15 seconds, making it a "good helper" for drivers to make their final sprint.

Creatine phosphate is a high-energy phosphate compound stored in muscles and other excitable tissues such as the brain and nerves. Creatine phosphate can be converted into ATP by transferring its phosphate group to ADP molecules under the catalysis of creatine kinase. The phosphocreatine in muscle cells not only has a large quantity (3 to 4 times its ATP content), but also generates ATP quickly, so phosphocreatine plays an important role in sprinting.

So the question is, why don't we retain more ATP in our bodies to replace the action of phosphocreatine and create new ATP? Mark Burnley, a senior lecturer in exercise physiology at the University of Kent, said, "ATP is a fairly heavy molecule, and 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 stores fat and carbohydrates as energy, and their weight is lighter than ATP

The rate at which phosphocreatine regenerates ATP is very fast, and most importantly, it can complete ATP generation without the involvement of oxygen, without any side effects. However, although phosphocreatine is abundant in muscles, its reserves are still limited, so your sprint cannot last too long. Our intelligent bodies have long thought of this. When the breakdown of phosphocreatine in the body is almost complete, you will not immediately "jump off the street" due to insufficient energy, but will be taken over by other energy mechanisms in the body to produce ATP from phosphocreatine.

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 their oxygen consumption and prepare in advance for the handover of ATP generation mechanisms in the future.

How to train this system

Firstly, it should be noted that the phosphocreatine system itself cannot work 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 sprinting, you need to increase the rest time between each sprint training round. However, if you want to improve your aerobic capacity through sprint training, you need to shorten your rest and recovery time for each sprint.

2. Breakthrough stage from the collective

Professional term: Glycolysis system

Function in cycling races: It can help you maintain maximum output power for 90-120 seconds and is commonly used for riders to break through from large groups

The glycolysis system is another energy mechanism for the synthesis of ATP. Unlike the synthesis of phosphocreatine, the glycolysis system 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 considered 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 rapidly provide energy using oxygen, which is more important for muscle contraction, but can only support a very short period of time. The energy generated by this system can reach approximately 100 times that of a regular aerobic system.

Once again, it should be reiterated that 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 are all working together, just with different percentages of energy supply at each stage

Many people who have conducted in-depth research will know that the glycolysis system produces lactic acid. Lactic acid is often associated with muscle fatigue, causing many car enthusiasts to avoid it. This is actually a complete misunderstanding. Lactic acid does not cause muscle fatigue. On the contrary, our muscle cells transfer lactic acid to the liver through the lactate cycle, where it is converted into glucose through gluconeogenesis, providing energy to the muscles again.

You can think of the lactate system as a buffering agent, "explained Sprague. There are even indications that when we start exercising, inactive muscles transport lactate to the liver as fuel, leading to an increase in blood lactate levels in our bodies

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 breakout action in the crowd. If you want to train this glycolysis system well, you must try to engage in high-intensity exercise in a short period of time. High intensity refers to exceeding 90% of your VO2MAX (maximum oxygen uptake), or you can choose to set the training intensity near the lactate threshold. Most coaches would recommend using a two-tier approach, with 80% of training programs conducted at low intensity and only 20% of training programs exceeding the lactate threshold.

3. Endurance cycling stage

Professional term: oxidative phosphorylation

The role in cycling races: allowing you to support the entire race with sufficient endurance

In addition to synthesizing ATP through phosphocreatine, glycolysis, and lactate, our body also delivers energy to muscles through other pathways during low-intensity exercise. During prolonged endurance cycling, enzymes in the mitochondria continuously oxidize nutrients (fatty acids) to provide you with energy, but the "cost" will be higher.

Nicholas Wilsmer, a lecturer in physical education at the University of Bath, said, "Oxidative phosphorylation consumes a large amount of oxygen and can produce 20 times more energy than the glycolytic system. However, its rate of ATP synthesis is slower, so oxidative phosphorylation can only play its role better when the intensity of exercise is low. It is the preferred 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 a relaxed speed. How do we define 'relaxed speed'? It's 75% lower than 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 your capillaries. The more capillaries you have in your body, the more oxygen enters your cells, and your performance on the court will be better.