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.

We’re living longer than in previous generations, with one in eight elderly Australians now aged over 85. But the current gap between life expectancy (“lifespan”) and health-adjusted life expectancy (“healthspan”) is about ten years. This means many of us live with significant health problems in our later years.

To increase our healthspan, we need planned, structured and regular physical activity (or exercise). The World Health Organization recommends 150–300 minutes of moderate-intensity exercise – such as brisk walking, cycling and swimming – per week and muscle strengthening twice a week.

Yet few of us meet these recommendations. Only 10% meet the strength-training recommendations. Lack of time is one of the most common reasons.

Walking is cost-effective, doesn’t require any special equipment or training, and can be done with small pockets of time. Our preliminary research, published this week, shows there are ways to incorporate strength-training components into walking to improve your muscle strength and balance.

Why walking isn’t usually enough

Regular walking does not appear to work as muscle-strengthening exercise.

In contrast, exercises consisting of “eccentric” or muscle-lengthening contractions improve muscle strength, prevent muscle wasting and improve other functions such as balance and flexibility.

Typical eccentric contractions are seen, for example, when we sit on a chair slowly. The front thigh muscles lengthen with force generation.

Our research

Our previous research found body-weight-based eccentric exercise training, such as sitting down on a chair slowly, improved lower limb muscle strength and balance in healthy older adults.

We also showed walking down stairs, with the front thigh muscles undergoing eccentric contractions, increased leg muscle strength and balance in older women more than walking up stairs. When climbing stairs, the front thigh muscles undergo “concentric” contractions, with the muscles shortening.

It can be difficult to find stairs or slopes suitable for eccentric exercises. But if they could be incorporated into daily walking, lower limb muscle strength and balance function could be improved.

This is where the idea of “eccentric walking” comes into play. This means inserting lunges in conventional walking, in addition to downstairs and downhill walking.

In our new research, published in the European Journal of Applied Physiology, we investigated the effects of eccentric walking on lower limb muscle strength and balance in 11 regular walkers aged 54 to 88 years.

The intervention period was 12 weeks. It consisted of four weeks of normal walking followed by eight weeks of eccentric walking.

The number of eccentric steps in the eccentric walking period gradually increased over eight weeks from 100 to 1,000 steps (including lunges, downhill and downstairs steps). Participants took a total of 3,900 eccentric steps over the eight-week eccentric walking period while the total number of steps was the same as the previous four weeks.

We measured the thickness of the participants’ front thigh muscles, muscle strength in their knee, their balance and endurance, including how many times they could go from a sitting position to standing in 30 seconds without using their arms. We took these measurements before the study started, at four weeks, after the conventional walking period, and at four and eight weeks into the eccentric walking period.

We also tested their cognitive function using a digit symbol-substitution test at the same time points of other tests. And we asked participants to complete a questionnaire relating to their activities of daily living, such as dressing and moving around at home.

Finally, we tested participants’ blood sugar, cholesterol levels and complement component 1q (C1q) concentrations, a potential marker of sarcopenia (muscle wasting with ageing).

What did we find?

We found no significant changes in any of the outcomes in the first four weeks when participants walked conventionally.

From week four to 12, we found significant improvements in muscle strength (19%), chair-stand ability (24%), balance (45%) and a cognitive function test (21%).

Serum C1q concentration decreased by 10% after the eccentric walking intervention, indicating participants’ muscles were effectively stimulated.

The sample size of the study was small, so we need larger and more comprehensive studies to verify our findings and investigate whether eccentric walking is effective for sedentary people, older people, how the different types of eccentric exercise compare and the potential cognitive and mental health benefits.

But, in the meantime, “eccentric walking” appears to be a beneficial exercise that will extend your healthspan. It may look a bit eccentric if we insert lunges while walking on the street, but the more people do it and benefit from it, the less eccentric it will become.

Ken Nosaka, Professor of Exercise and Sports Science, Edith Cowan University

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