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.

Children with traumatic experiences in their early lives have a higher risk of obesity. But as our new research shows, this risk can be reduced through positive experiences.

Childhood traumatic experiences are alarmingly common. Our analysis of data from nearly 5,000 children in the Growing Up in New Zealand study revealed almost nine out of ten (87%) faced at least one significant source of trauma by the time they were eight years old. Multiple adverse experiences were also prevalent, with one in three children (32%) experiencing at least three traumatic events.

Childhood trauma includes a range of experiences such as physical and emotional abuse, peer bullying and exposure to domestic violence. It also includes parental substance abuse, mental illness, incarceration, separation or divorce and ethnic discrimination.

We found children from financially disadvantaged households and Māori and Pasifika had the highest prevalence of nearly all types of adverse experiences, as well as higher overall numbers of adversities.

The consequences of these experiences were far-reaching. Children who experienced at least one adverse event were twice as likely to be obese by age eight. The risk increased with the number of traumatic experiences. Children with four or more adverse experiences were nearly three times more likely to be obese.

Notably, certain traumatic experiences (including physical abuse and parental domestic violence) related more strongly to obesity than others. This highlights the strong connection between early-life adversity and physical health outcomes.

Connecting trauma to obesity

One potential explanation could be that the accumulation of early stress in children’s family, school and social environments is associated with greater psychological distress. This in turn makes children more likely to adopt unhealthy weight-related behaviours.

This includes consuming excessive high-calorie “comfort” foods such as fast food and sugary drinks, inadequate intake of nutritious foods, poor sleep, excessive screen time and physical inactivity. In our research, children who experienced adverse events were more likely to adopt these unhealthy behaviours. These, in turn, were associated with a higher risk of obesity.

Despite these challenges, our research also explored a promising area: the protective and mitigating effects of positive experiences.

We defined positive experiences as:

• parents in a committed relationship
• mothers interacting well with their children
• mothers involved in social groups
• children engaged in enriching experiences and activities such as visiting libraries or museums and participating in sports and community events
• children living in households with routines and rules, including those regulating bedtime, screen time and mealtimes
• children attending effective early childhood education.

The findings were encouraging. Children with more positive experiences were significantly less likely to be obese by age eight.

For example, those with five or six positive experiences were 60% less likely to be overweight or obese compared to children with zero or one positive experience. Even two positive experiences reduced the likelihood by 25%.

How positive experiences counteract trauma

Positive experiences can help mitigate the negative effects of childhood trauma. But a minimum of four positive experiences was required to significantly counteract the impact of adverse events.

While nearly half (48%) of the study participants had at least four positive experiences, a concerning proportion (more than one in ten children) reported zero or only one positive experience.

The implications are clear. Traditional weight-loss programmes focused solely on changing behaviours are not enough to tackle childhood obesity. To create lasting change, we must also address the social environments, life experiences and emotional scars of early trauma shaping children’s lives.

Fostering positive experiences is a vital part of this holistic approach. These experiences not only help protect children from the harmful effects of adversity but also promote their overall physical and mental wellbeing. This isn’t just about preventing obesity – it’s about giving children the foundation to thrive and reach their full potential.

Creating supportive environments for vulnerable children

Policymakers, schools and families all have a role to play. Community-based programmes, such as after-school activities, healthy relationship initiatives and mental health services should be prioritised to support vulnerable families.

Trauma-informed care is crucial, particularly for children from disadvantaged households who face higher levels of adversity and fewer positive experiences. Trauma-informed approaches are especially crucial for addressing the effects of domestic violence and other adverse childhood experiences.

Comprehensive strategies should prioritise both safety and emotional healing by equipping families with tools to create safe, nurturing environments and providing access to mental health services and community support initiatives.

At the family level, parents can establish stable routines, participate in social networks and engage children in enriching activities. Schools and early-childhood education providers also play a key role in fostering supportive environments that help children build resilience and recover from trauma.

Policymakers should invest in resources that promote positive experiences across communities, addressing inequalities that leave some children more vulnerable than others. By creating nurturing environments, we can counterbalance the impacts of trauma and help children lead healthier, more fulfilling lives.

When positive experiences outweigh negative ones, children have a far greater chance of thriving – physically, emotionally and socially.

Ladan Hashemi, Senior Research Fellow in Health Sciences, University of Auckland, Waipapa Taumata Rau

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