[We asked an expert] How to walk using the PRO TREK Smart WSD-F21HR, which can measure your heart rate, to help you improve your endurance without fatigue?

Many people know that heart rate is said to be useful for managing people's physical condition and for athletes' training. Simply put, heart rate is the number of times the heart beats per minute. The average adult's resting heart rate is said to be about 60 to 80 beats per minute. Naturally, the rate at which heart rate increases varies depending on the level of exercise

Professor Maekawa Yoichi (Department of Physical Education, International Budo University) has a track record of placing 6th in the Lake Saroma 100km Ultra Marathon (1999) and completing the Mount Fuji Climbing Race. He is also well versed in heart rate research, having even measured and verified his own heart rate. While at Tsukuba University, he ran the 5th leg of the Hakone Ekiden. He gives lectures around the country, instructing a wide range of people, from beginners to advanced runners, from junior athletes to masters, and also provides instruction in everything from walking to jogging in health promotion programs. His major publications include "The Marathon Textbook You Never Knew."

This time, we spoke with Professor Yoichi Maekawa of the Department of Physical Education at International Budo University, a specialist in training science, about whether it's possible to climb mountains without getting tired or to improve your physical abilities using CASIO's PRO TREK Smart WSD-F21HR (hereinafter referred to as F21HR), an outdoor smartwatch that can measure heart rate, and how to put this into practice.We then actually used the F21HR to climb mountains while controlling our heart rate, and here is our report on the results

table of contents

• Why does an increased heart rate make you tired?
• The type of exercise you do will change depending on your heart rate zone, which indicates the intensity of your exercise
• The key to hiking without getting tired is "burning fat while walking"
• When climbing mountains, be aware of fluctuations in your heart rate on steep slopes
• To improve your endurance, climb in heart rate zones 3-4
• Maximum oxygen intake is also important for a body that doesn't tire easily
• I actually tried climbing a mountain with my heart rate in mind, with the aim of not getting tired and building endurance
• summary

Why does an increased heart rate make you tired?

For example, let's say there is a 5km stretch of flat paved road. Whether the same person runs this distance at full speed or walks slowly over a long period of time, the distance traveled is the same, so the energy consumed will be roughly the same.

However, the person who ran at full speed felt more tired after the run. Why did they feel differently tired even though they burned the same number of calories? The difference is that one person burned 250 calories in 20 minutes, while the other burned 250 calories over an hour. This is where heart rate comes into play

The former is running with a fairly high heart rate, while the latter is walking without increasing the heart rate much. The crucial difference between the two when they get tired is the "energy source used ." The former, running at full speed, uses glycogen as energy, while the latter primarily uses fat as energy. If you continue to consume glycogen, you will become exhausted and unable to move. As long as you are burning fat, you can continue exercising. In other words, the high heart rate during exercise is a function of the energy source used, and this greatly affects how tired you feel and the effects of exercise .

Incidentally, when it comes to burning body fat, there's actually not much difference between the two. That's because walking is aerobic exercise, so fat is used while walking, but when running at full speed, fat is not used as much while running, but fat is burned during the fatigue recovery process after running. This is the "afterburning" process, where fat is burned after exercise. In terms of burning fat, even though the way you get tired is different, the overall effect is the same

Although he is not an expert in mountain climbing, Professor Yoichi Maekawa is well versed in the field of heart rate, having even measured and verified his own heart rate. He is also a senior coach certified by the Japan Sport Association and the Japan Association of Athletics Federations

The type of exercise you do will change depending on your heart rate zone, which indicates the intensity of your exercise

A high (low) heart rate is not an absolute number, but rather a relative value for each person. In order to use heart rate to target exercise, it is important to first know what percentage of your maximum heart rate you exercised at. Although there are individual differences, your maximum heart rate (bpm) can be calculated by subtracting your actual age from 220. For this reason, the upper limit of your heart rate generally decreases with age

If you're just trying to improve your health, it's enough to keep moving without getting out of breath. If you're trying to burn fat, you need to exercise at a slightly higher level. Anything beyond that is training territory. If your goal is to improve your endurance, you need to push yourself further. However, it's not enough to just get your heart rate close to 100%. If your heart rate is over 90% of your maximum, the exercise will be more effective at improving anaerobic endurance rather than aerobic endurance

• Zone 5: 90-100%...Improves anaerobic endurance
• Zone 4: 80-90%...Improves speed endurance
• Zone 3: 70-80%...Improved aerobic endurance
• Zone 2: 60-70%...fat burning
• Zone 1: 50-60% - Warm-up, cool-down, walking

*For more information on heart rate zones, the PRO TREK Smart website . % indicates the percentage of maximum heart rate.

With the WSD-F21HR, you can check your heart rate zone along with your heart rate while you're moving. (Note: To do this, you'll need to set your maximum heart rate and resting heart rate initially.)

The key to hiking without getting tired is "burning fat while walking"

If your heart rate is below 80% of your maximum (zone 3 or below), you are basically getting enough oxygen, and your body is converting fat into energy. If it's between 60% and 70% (zone 2), you're definitely burning fat . If you're using fat as energy, fatigue won't accumulate. However, if you don't exercise much on a regular basis, lactic acid may be produced (leading to muscle fatigue) even in that range. Also, the way lactic acid is produced differs depending on whether or not you can use fat (as energy).

If you can keep your heart rate below 70% of your maximum, you can convert fat into energy and climb without getting tired

When climbing mountains, be aware of fluctuations in your heart rate on steep slopes

Lactic acid is produced temporarily when you sprint at the end of a marathon, but even in a marathon, if you keep your pace constant and keep it down, lactic acid generally doesn't build up. However, when climbing a mountain, you push hard to lift your body, which uses your muscles . This damages the muscles, so lactic acid may be produced. If lactic acid is produced, your heart rate is increasing. In other words, you are in an oxygen deficiency state. There is not enough oxygen for the exercise intensity. If your heart rate increases and you are not receiving the necessary amount of oxygen, lactic acid will build up and fatigue will build up.

Additionally, if you're just walking up a gentle slope, your heart rate is unlikely to suddenly rise. However, this is not the case when climbing a mountain. Naturally, you'll encounter more diverse terrain than in a marathon, with slopes varying in both direction, climbing over rocky areas, and varying ups and downs, so your heart rate is more likely to fluctuate. Excessive fluctuations in your heart rate can also be a negative factor in terms of fatigue

If you want to climb without getting tired, it should be easier to walk over time and keep your heart rate from rising and falling as much as possible . Your body can't handle a constantly rising heart rate, so even if it rises for a moment, let it drop again and return to a steady state. If you can maintain a steady state for a long time, I think you'll be able to climb without too much difficulty. Keeping your heart rate as low as possible will ultimately reduce fatigue. In that sense, if you feel short of breath, check your heart rate, and if it's high, slow down your climbing pace a little or take a break. By taking measures like this, I think anyone can move forward without straining themselves.

Because mountains have many ups and downs, your heart rate tends to fluctuate greatly

To improve your endurance, climb in heart rate zones 3-4

For example, if a beginner marathon runner's goal is to complete the entire race, there is no need for strenuous training. They would be instructed to slowly increase the distance they run without increasing their heart rate. However, if they want to improve their finishing time, they will need to get used to running at a faster pace. This means they will need to train to increase their heart rate and improve their endurance. When it comes to building endurance, it is effective to exercise at 70-90% of your maximum heart rate, in a heart rate zone around 3 or 4. The important thing to remember is that pushing yourself to the limit does not necessarily mean you will have better endurance.

As you continue training, your heart rate will become less likely to rise, even with the same exercise load. This means you can increase your speed. Also, even if a training person's heart rate suddenly increases, it will drop back down after about a minute of rest, but someone who is not exercising will remain out of breath and their heart rate will not drop easily

If you walk at 70-80% of your maximum heart rate, your heart rate will gradually increase less even with the same exercise, and you will develop endurance

Maximum oxygen intake is also important for a body that doesn't tire easily

Another indicator of endurance is that people who can walk fast even when climbing a mountain with lots of ups and downs likely have a high maximal oxygen uptake (VO2 max (V with a dot)). Maximum oxygen uptake is the maximum amount of oxygen the body can take in. If maximum oxygen uptake increases, the body is less likely to experience oxygen deficiency, meaning you are less likely to get tired and you will be able to tolerate more intense exercise. For the same exercise, your stamina will last longer, and for the same distance, your speed will increase. To improve maximum oxygen uptake, it is effective to consciously raise and lower your heart rate . Alternating periods of exertion and rest will stimulate oxygen uptake rather than continuing to apply a constant load. This is what is known as "interval training."

It's impossible to climb a mountain above your level in one go. You need to take it step by step so that oxygen can be delivered to your entire body. This is why cardiopulmonary function, such as the heart and lungs, is important. It's better to climb the mountain slowly and for long periods of time so that oxygen can be delivered to the extremities of your body. The higher the mountain you go, the more important your maximum oxygen intake becomes. How much oxygen can you utilize in a thin atmosphere? The higher you climb, the more important it becomes

An effective way to improve your maximum oxygen intake is to increase your heart rate

Next page: Trying out heart rate mountain climbing with the WSD-F21HR

I actually tried climbing a mountain with my heart rate in mind, with the aim of not getting tired and building endurance

Based on Professor Maekawa's advice, I immediately tried out two different walking patterns on Mount Oyama (1,251.7m above sea level) in Tanzawa in late October: one that wouldn't tire me out, and one that was designed for training. The climb started from Ybitsu Pass (761m above sea level), and I planned to camp overnight, carrying a load of 9,215kg. The author (41 years old)'s maximum heart rate was 179 bpm

The backpack weighs 9.215 kg, which is roughly the weight of a tent for one night

Before starting the climb, I made sure to set up the F21HR. I set my resting heart rate and maximum heart rate, and also set the "Zone Alert" function to sound an alert if I exceeded Zone 2

To avoid fatigue, climb at a pace that burns fat

First, I started by learning how to climb without getting tired. It was chilly, so I wore a thin fleece jacket. I climbed as much as possible in heart rate zone 2. To recap, zone 2 is for burning fat, and zone 3 is for improving endurance. About 400 meters into the climb, my heart rate suddenly rose, and I had trouble getting a sense of how my heart rate was rising, but gradually I got used to my sense of pace. Because I had the zone alert set, the watch vibrated to notify me when I exceeded zone 2, and when I looked at the display, the zone number was flashing "3." The alert helped me quickly get a sense of my pace

Once I got the hang of it, I was able to climb while keeping my heart rate at around 110 bpm, within heart rate zone 2. As for my condition during the climb, my breathing became a little quicker and I felt like I was sweating, but not so much that I was dripping. I was climbing at a pace that allowed me to talk while climbing. When the gradient increased, I tried to slow down my pace and take small steps to avoid raising my heart rate. Even though I was carrying about 9 kg of luggage, the climb to the summit of Mt. Daisen took 80 minutes, the course time

Check your heart rate zone with alerts and vibrations

By the way, I descended from the summit to Ybitsu Pass as quickly as possible, but although I was sweating easily, my heart rate did not increase and I was in zone 2 or zone 1 (50-60% of maximum heart rate). On the way down, my pace increased quite a bit, but the mountain trail had some unevenness and difficult footing in places, so my pace slowed down in places. My heart rate remained low. For reference, the graph below shows my heart rate on the climb to the summit at that time

I'm focusing on training and trying to stay in Zone 3..

At first, I struggled to keep up my pace while staying in Zone 2, but I was able to get used to it quickly. After taking a short break, I started climbing again while staying in Zone 3, focusing on training

Carrying the same approximately 9kg load, I climbed while focusing on heart rate zone 3. Heart rate zone 3 is for endurance, and zone 4 is for improving muscle strength and stamina. My heart rate began to rise rapidly about 400m into the climb. In reality, it's quite difficult to maintain zone 3 while climbing, because my heart rate would inevitably rise to zone 4

When I reach heart rate zone 4, I'm out of breath and my nose is running. I feel like sweat is pouring out of my whole body, especially in my armpits, chest, and back. I'm sweating so much that I want to take off my fleece jacket. I try to climb as fast as possible, even on steeper slopes, taking breaks at appropriate intervals to get back to zone 3, but whenever I rest, I risk dropping down to zone 2

When your heart rate is high, it takes quite some getting used to to maintain that zone. My body started to tire midway through, and I was forced to slow down occasionally. I reached the summit in 53 minutes. This means I had climbed in about two-thirds of the 80-minute course time. When the gradient got steeper towards the end, my legs felt heavy, perhaps due to muscle fatigue. Zone 4 (80-90% of maximum heart rate) is an area where the body is under a lot of strain and lactic acid is produced. It's not surprising that it felt heavy to lift my legs

The display is easy to see even while climbing. When climbing with training in mind, my heart rate zone tends to be at 4

The diagram below shows my second climb, where I aimed to improve my endurance and focused on Zone 3. However, I ended up in Zone 4

summary

It's not that difficult to use heart rate to climb without getting tired. In my case, staying in Zone 2 (60-70% of my maximum heart rate) was roughly equivalent to climbing while maintaining my course time. However, this time I was carrying about 9 kg of weight. The guideline will likely change depending on the conditions, including the temperature

If you burn fat as energy and your heart rate is below 80% of your maximum, lactic acid is less likely to be produced. However, when climbing steeply, you should aim to climb at a moderate pace. While this will vary depending on the individual and the weather, you will likely sweat a little, so you will need to adjust your clothing to suit the conditions

On the other hand, for mountain climbing for training purposes, I recommend zones 4 or 3. Perhaps because it was my first time climbing while paying attention to my heart rate, I found it difficult to maintain a high heart rate. Lactic acid gradually builds up, my body becomes fatigued, and my thinking becomes dull. However, it was at times like these that the F21HR's zone alerts came in very handy. In terms of building a body that is less prone to fatigue, consciously training your heart rate up and down to increase your maximum oxygen intake is also effective

Maintaining a heart rate zone is partly a matter of intuition, but it seems to take some experience to get the hang of it. In that sense, the PRO TREK Smart WSD-F21HR easily measures your heart rate on your wrist, and the display and alerts make it easy to understand your heart rate zone. Of course, you can also check your pace, distance, and altitude at any time, and you can even set it to measure your maximum oxygen intake. This smartwatch is ideal for a wide range of people, from those who want to enjoy a leisurely, fatigue-free hike to those who want to challenge themselves with endurance and stamina.

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