1st Revision: Lucy Walker 
Short Explanatory Video
Regular exercise has numerous benefits for your physical and mental health. In the long term, exercise can protect you from chronic conditions like obesity, diabetes, high blood pressure, and cardiovascular disease.
We are going to dig deep into what happens to our bodies when we move. Let's take a close look.
About muscles
Muscles are one of the most important parts of your body. Getting enough exercise is as important to a healthy body as eating healthy food and getting enough sleep.
Studies have shown that increased levels of muscle mass lead to more bone density and more strength in the arms, legs, back and even feet. This means that working out regularly helps you to avoid chronic problems such as osteoporosis.
Why do muscles contract?
When you take a deep breath, the muscles of your chest and stomach contract. This same thing happens when you lift weights; your muscle fibres pull on themselves, forcing themselves to work harder. Because of this, your muscles grow stronger with time.
Contraction might also happen when you stretch your muscles, such as when you hold or pick up something. In this case, the muscles are stretched and then the muscle fibres begin to pull, causing them to contract.
The more you stretch your muscles and make them work against resistance, the stronger they get.
How our muscles contract?
When you want to lift your legs or move your arms to pick something up, your brain sends a signal down your spinal cord. This signal then travels along nerves that spread out from the spine until they reach the muscles you want to move.
Inside each muscle fibre, there are "sarcomeres." Sarcomeres are made of tiny protein strands that slide back and forth, pulling on each other to create the contraction that makes the fibres shorter and shorter.
Different types of contractions and where they occur
Contractions may also be referred to as "shortening." Following are the three types of muscle contractions;
- Concentric shortening happens when your muscle is actively shortened. For example, when doing a bicep curl, your bicep is shortened as the elbow moves up.
- Eccentric shortening happens when your muscle is lengthened but still under load, such as extending your arm above your head. Even though the arm is extended, a lot of the tension remains in the muscle because it is attached to something heavy. This type of contraction can help your muscles to get stronger on their own.
- Isometric contraction happens when your muscle is actively stretched. This can help build up your muscle strength, but it doesn't affect the length of the muscle.
Strength training and physical activity benefit our bodies in many ways.
Exercising regularly can increase muscle mass and bone density. It keeps you fit even in the older ages.
The heart and exercise
It's not just the muscles in your biceps that are worked during exercise. Your heart is also stimulated to pump more blood around the body, making it the main muscle used during exercise.
As your workout becomes more intense, your heart pumps blood with more force to get more oxygen and nutrients to the muscles.
Exercise is an important part of maintaining a healthy heart as when you work out more regularly your heart also gets stronger and healthier.
Your brain and exercise
As you've probably noticed, exercising triggers a chemical reaction in your brain that makes you feel good.
This is what happens to your brain when you exercise:
- When you exercise, your brain releases chemicals called ‘endorphins’.
- As you start to exercise, the endorphins reach your brain to make you feel good.
- Before long they start pumping a chemical called ‘dopamine’ into your bloodstream. This makes you feel happy and energetic. ²
Your nervous system and immune system vs exercise
Nervous system
Exercise benefits your nervous system by making it stronger and more efficient. For example, your brain sends you a signal to breathe more deeply when your heart rate increases during exercise. The more you work out, the better your nervous system works.
Immune system
Exercise is also good for your immune system. When you exercise regularly, your body's natural defences are strengthened and prevent diseases from occurring.
Exercise also helps fight infection by increasing circulation to the sites of infection. This can help you overcome any illness you have, faster than if you don’t move as much.
General wellbeing and exercise
Exercise not only makes you stronger and healthier but also makes you more energetic and helps curb stress.
Apart from the factors mentioned above, regular exercise can :
- make you feel happier
- help with weight loss
- be good for your muscles and bones
- increase your energy levels
- reduce your risk of chronic disease
- help skin health
- help your brain health and memory
- help with relaxation and sleep quality
- reduce pain
- promote a better sex life
You must include physical activity regularly in your life, if you want to be at your best and perform optimally.
References:
- Padulo J, Laffaye G, Chamari K, Concu A. Concentric and eccentric: muscle contraction or exercise?. Sports Health. 2013;5(4):306
- Heijnen, Sasika, Bernhard Hommel, and Armin Kibele. 2015. “Neuromodulation of Aerobic Exercise—A Review.” Frontiers in Psychology 6 (1890).
