As many of us hit the gym or go for a run to recover from the silly season, you might notice a bit of extra muscle soreness.

This is especially true if it has been a while between workouts.

A common misunderstanding is that such soreness is due to lactic acid build-up in the muscles.

Research, however, shows lactic acid has nothing to do with it. The truth is far more interesting, but also a bit more complex.

It’s not lactic acid

We’ve known for decades that lactic acid has nothing to do with muscle soreness after exercise.

In fact, as one of us (Robert Andrew Robergs) has long argued, cells produce lactate, not lactic acid. This process actually opposes not causes the build-up of acid in the muscles and bloodstream.

Unfortunately, historical inertia means people still use the term “lactic acid” in relation to exercise.

Lactate doesn’t cause major problems for the muscles you use when you exercise. You’d probably be worse off without it due to other benefits to your working muscles.

Lactate isn’t the reason you’re sore a few days after upping your weights or exercising after a long break.

So, if it’s not lactic acid and it’s not lactate, what is causing all that muscle soreness?

Muscle pain during and after exercise

When you exercise, a lot of chemical reactions occur in your muscle cells. All these chemical reactions accumulate products and by-products which cause water to enter into the cells.

That causes the pressure inside and between muscle cells to increase.

This pressure, combined with the movement of molecules from the muscle cells can stimulate nerve endings and cause discomfort during exercise.

The pain and discomfort you sometimes feel hours to days after an unfamiliar type or amount of exercise has a different list of causes.

If you exercise beyond your usual level or routine, you can cause microscopic damage to your muscles and their connections to tendons.

Such damage causes the release of ions and other molecules from the muscles, causing localised swelling and stimulation of nerve endings.

This is sometimes known as “delayed onset muscle soreness” or DOMS.

While the damage occurs during the exercise, the resulting response to the injury builds over the next one to two days (longer if the damage is severe). This can sometimes cause pain and difficulty with normal movement.

The upshot

Research is clear; the discomfort from delayed onset muscle soreness has nothing to do with lactate or lactic acid.

The good news, though, is that your muscles adapt rapidly to the activity that would initially cause delayed onset muscle soreness.

So, assuming you don’t wait too long (more than roughly two weeks) before being active again, the next time you do the same activity there will be much less damage and discomfort.

If you have an exercise goal (such as doing a particular hike or completing a half-marathon), ensure it is realistic and that you can work up to it by training over several months.

Such training will gradually build the muscle adaptations necessary to prevent delayed onset muscle soreness. And being less wrecked by exercise makes it more enjoyable and more easy to stick to a routine or habit.

Finally, remove “lactic acid” from your exercise vocabulary. Its supposed role in muscle soreness is a myth that’s hung around far too long already.

Robert Andrew Robergs, Associate Professor – Exercise Physiology, Queensland University of Technology and Samuel L. Torrens, PhD Candidate, Queensland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

“What are the main factors in forming someone’s personality?” – Emma, age 10, from Shanghai

Hello Emma, and thank you for this very interesting question!

Let’s start by exploring what we mean by personality. Have you noticed no two people are completely alike? We all see, experience, and understand the world in different ways.

For example, some people love spending time with friends and being the centre of attention, whereas other people are more shy and enjoy having time to themselves.

Your unique personality is shaped by your genes as well as various influences in your environment. And your personality plays an important role in how you interact with the world.

The big five

Did you know there are scientists who spend time researching personality? Their research is concerned with describing the ways people differ from each other, and understanding how these differences could be important for other parts of life such as our health and how well we do in school or at work.

There are many different perspectives on personality. A widely accepted viewpoint based on a lot of research is called the five factor model or the “big five”. According to this theory, a great deal of a person’s personality can be summarised in terms of where they sit on five dimensions, called traits:

1. the introversion-extraversion trait refers to how much someone is outgoing and social (extroverted) or prefers being with smaller groups of friends or focusing on their own thoughts (introverted)
2. agreeableness captures how much someone tends to be cooperative and helps others
3. openness to experience refers to how much a person is creative and enjoys experiencing new things
4. neuroticism describes a person’s tendency to experience negative feelings, like worrying about things that could go wrong
5. conscientiousness encompasses how much a person is organised, responsible, and dedicated to things that are important to them, like schoolwork or training for a sports team.

A person can have high, low, or moderate levels of each of these traits. And understanding whether someone has higher or lower levels of the big five can tell us a lot about how we might expect them to behave in different situations.

So what shapes our personalities?

A number of factors shape our personalities, including our genes and social environment.

Our bodies are made up of many very small structures called cells. Within these cells are genes. We inherit genes from our parents, and they carry the information needed to make our bodies and personalities. So, your personality may be a bit like your parents’ personalities. For example, if you’re an outgoing sort of person who loves to meet new people, perhaps one or both of your parents are very social too.

Personalities are also affected by our environment, such as our experiences and our relationships with family and friends. For example, some research has shown our relationships with our parents can influence our personality. If we have loving and warm relationships, we may be more agreeable and open. But if our relationships are hurtful or stressful, this may increase our neuroticism.

Another study showed that, over time, young children who were more physically active were less introverted (less shy) and less likely to get very upset when things don’t go their way, compared to children who were less physically active. Although we don’t know why this is for sure, one possible explanation is that playing sport leads to reduced shyness because it introduces children to different people.

While we’re learning more about personality development all the time, research in this area presents quite a few challenges. Many different biological, cultural and environmental influences shape our development, and these factors can interact with each other in complex ways.

Is our personality fixed once we become adults?

Although we develop most of our personality when we are young, and people’s personalities tend to become more stable as they get older, it is possible for aspects of a person’s personality to change, even when they are fully grown.

A good example of this can be seen among people who seek treatment for conditions like anxiety or depression. People who respond well to working with a psychologist can show decreases in neuroticism, indicating they become less likely to worry a lot or feel strong negative feelings when something stressful happens.

Hello, Curious Kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to mailto:[email protected]

Tim Windsor, Professor, Director, Generations Research Initiative, College of Education, Psychology and Social Work, Flinders University and Natalie Goulter, Lecturer, College of Education, Psychology and Social Work, Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.