Organ of Longevity

How to reverse an ageing body?

What is the difference between a youthful and an ageing body?

Is it wrinkles?

Walking Speed?

Endurance?

Movement?

Flexibility?

Muscle Mass?

Muscle Strength?

Well, it is all of the above. The first is a result of loss of skin elasticity and collagen, and the rest pertains to the loss of physical health attributes.

Why do we increasing lose our physical ability, which results in symptoms of ageing such as loss of physical performance?

The answer to this is simple; ageing naturally results in the loss of regenerative abilities of our body. But this is only the first part of the answer that perhaps is out of our control. What is in our control, however, is how we lead our lives, sedentary or active? This aspect under our conscious control points directly to the law of use or loose.

To elaborate on this point further, what is it that we possess in youth that gives us a youthful body and excellent physical performance that we slowly lose as we age? The answer is the quality of muscles surrounding our bones and joints that allow us to move from one place to another and help us become physically functional and resourceful.

The quality of these muscles and their ability to get recruited by the brain to perform a physical task is what differentiates a youthful from an aged body. These different muscles in our body can broadly be divided into smooth muscle fibres and striated muscle fibres. The smooth muscle fibres make up all organs outside of our conscious control, and striated are the ones within our voluntary control. All these muscle fibres are connected to the central nervous system that comprises the brain and the spinal cord through various nerve cells known as neurons that allow for action potential to stimulate the muscle and make it perform its function or activity.

All the internal organs in the body are connected and enabled through an autonomous nervous system that is outside our conscious control, such as the diaphragm, digestive organs, heart etc. However, the organs known as our skeletal muscles surrounding our skeletal tissues, such as arms, legs, chest and back, are within our conscious control and form a part of the voluntary nervous system.

Today to understand how we can slow down our ageing process, we will focus on this voluntary aspect of the nervous system and how it can keep us youthful and energetic even as we age.

These skeletal muscles can broadly be divided into two categories:

1)?????Type 1 muscle fibres

2)?????Type 2 muscle fibres

When we are doing some mild-intensity exercise like walking or are stationary, our body recruits type 1 muscle fibres to keep us in a specific posture or to complete low-intensity tasks. These type 1 fibres are known as slow twitch cardio fibres because they produce energy using oxygen and food, which is generated at a slower pace but is very sustainable and does not stress our metabolism.

This food energy refers to either fatty acids (broken down from fat) or glucose (broken down from carbs). ?Fatty acids are the primary fuel used to power up lower-intensity activities. So, during low-intensity exercise that doesn’t require muscles to contract forcefully, type 1 muscle fibres are used that produce much energy, albeit at a slower rate due to their high oxidative (using oxygen to burn food for energy) and low glycolytic (carbohydrates burning) capacity.

However, when physical exertion increases because we translate walking into fast walking or sprinting to give us extra power and strength, type 2 muscle fibres are activated at the joints to keep the pace high, exercise very intense and churn out more energy faster. These type 2 fibres are also known as fast twitch strength fibres because they produce energy using only food in the absence of oxygen, also known as anaerobic energy production, which is at a more rapid pace but is very short-lived while stressing our metabolism. The ‘fast’ or ‘slow’ twitch refers to how quickly the muscle fatigues.

(Image credit: verywell)

Depending on whether the training zone is less intense or more, different muscle fibres are recruited based on the need for the number of muscles to fulfil the requirement of the task, the more intense the task, the more muscles needed, where just the type 1 muscles are unable to complete the task by themselves.

This energy that your muscles require to contract and relax to complete the task is known as adenosine triphosphate (ATP) generation, which is directly proportionate to exercise intensity. So, at lower energy intensities, those type 1 (slow twitch) muscle fibres are exceptionally well designed to use food energy sufficiently to provide ATP, which can be sustained for a very long time. You can think of your muscles as dual energy utilising engine, like a hybrid engine car that can use a clean fuel source like electricity (fatty acid) for a long duration, flat road (lower intensity) drives and also use a fast-powering fuel source like diesel (glucose) for a short duration, incline, mountainous terrain (higher intensity) drives.

(Image credit: Medium)

So, when exercise intensity increases, the necessity to generate ATP at faster rate increases as well, and it gets to a point where (electric engine) fatty acids alone are not sufficient to generate ATP. Thus, we need another system to kick in, and that energy system is burning glucose in type 2 muscle fibres which is a faster energy system.

As far as food energy burning is concerned, whether the energy required in a physical activity qualifies as aerobic or anaerobic comes down to the speed with which the muscle is demanding ATP. Aerobic exercise means ATP demand is sufficiently slow that it can be met through the primary powerplant of the muscle (mitochondrion) oxidation of fatty acids, which gives out 36 molecules of ATP.

High-intensity activities demand anaerobic energy as it exceeds the capacity of the mitochondria oxidative capacity, further ATP is generated in the secondary powerplant of muscle known as the ‘cytosol’ using glucose, and for the highest intensity activity when the ATP demand even exceeds the cytosolic production of ATP, that’s when the already stored ATP in the muscle is used as a fuel source, as no energy system is needed to generate it and because there is no time for the muscle to generate it from scratch.

The already stored ATP is instantly used, and that is why the body holds the very minimal quantity of ATP, which is used for the highest intensity exercise such as sprints, boxing, kicking and heavy weightlifting. In such activities, the body needs to synthesise it very fast as it’s a pure anaerobic activity, thus after all readily available ATPs are used, the muscles require several bouts of rest in between to recover and synthesise ATP for storage so that none of the energy systems is needed to generate quick action of the muscle.

Another fastest way to resynthesise ATP in the muscle is known as the phosphagen system (the creatine phosphate system). This creatine phosphate molecule in the muscle donates a phosphate to adenosine diphosphate (ADP) to produce ATP, and this, too, doesn’t require oxygen for generation and thus can occur anaerobically.

Due to a sedentary lifestyle and ageing, our body’s ability to repair mitochondria diminishes and also, since type 2 muscle fibres are metabolically costly tissue to maintain, meaning requiring calories are they are very active, the body slowly breaks them down, leading to the reduction of their size and strength known as ‘muscle atrophy’. Both reasons,

1)?????Damaged mitochondria

2)?????Atrophied muscles

Contribute to diminished fat burning in the body, reduced energy levels and reduced lean shape, size and physical strength as we age due to continuous disuse of the body. This is one of the primary causes of old age frailty, reduced physical freedom, muscle pain, inability to recover from falls and injuries and thus diminished quality of life. The only way to retain and maintain the type 2 muscle fibres as the body ages is to do work every other day that stimulates and recruits these muscle fibres, such as resistance training with lifting external weight and doing bodyweight exercises such as squats, plank, step-ups, push-ups and pull-ups.

The good news for individuals who do resistance training at least three times a week is that carrying higher type 2 muscle fibres is linked to mitigating many risk factors associated with lifestyle diseases such as obesity, diabetes, heart disease and other metabolic problems such as autoimmune disease, low immunity, low resting metabolic rate and low glucose tolerance. Using these muscle fibres has also been linked to lower inflammation that is associated with ageing because of myokines released from the contraction of muscles, which are hormones that are anti-inflammation; thus, skeletal muscles today are recognized in the medical community as essential endocrine glands to enhance life and health span.

Image Credit: ResearchGate

Therefore, the only solution to overcome this problem is to regularly move the bodies across different training zones from aerobic activity to short anaerobic activities such as sprinting, swimming and resistance training. Aerobic activity stimulates the repair and growth of mitochondria in the muscle cell, and anaerobic exercise promotes the size and strength of type 2 muscle fibres. Both lead to the slowing of physical ageing and provide us with a higher quality of life, especially after retirement when we have the time and wealth to enjoy life.