Grip strength improves in children, but other measures of muscle performance deteriorate

Physical fitness in children refers to their ability to perform physical activity. Their level of physical fitness is critical not only for success in sports and athletics, but also for good health.

Aerobic exercise – the ability to deliver oxygen to the body’s gigantic muscles during sustained physical activity such as running, cycling or swimming – has long been known to be critical for the health of both children and adults. Muscle fitness refers to the ability of muscles to produce maximum force, quickly and repeatedly – ​​otherwise known as strength, power, and endurance.

Research into the health benefits of good muscle condition in children and adolescents has increased significantly over the past decade. systematic review The results of these studies showed that low muscle fitness is associated with high body fat, penniless bone health and low self-esteem, as well as a high risk of developing heart disease later in life.

Such discoveries are the reason why both World Health ORganisation AND U.S. Department of Health and Human Services It is currently recommended that children aged 5 to 17 participate in muscle and bone strengthening activities at least three days a week.

We are professor of kinesilogy AND epidemiolog who conduct research focusing on fitness and health. In 2019, our research team published test who collected over 30 years of data on the aerobic fitness of 1 million children from 19 high- and upper-middle-income countries, including Australia, Canada, and the United States. We found that the aerobic fitness of children in these countries declined significantly from 1981 to about 2000, and there has been no change since then.

This study got us wondering: Did the kids’ muscle fitness decline as well? So we decided to look at that, too.

Muscle fitness of today’s children

Our research team reviewed hundreds of studies. They included decades of data on the muscle performance of tens of millions of children ages 9 to 17, mostly from high- and upper-middle-income countries. We focused on measures of grip strength, the standing broad jump for leg power, and sit-ups for abdominal endurance, because these are the most common ways that researchers around the world measure muscle performance in children.

We found that in most of these countries grip strength has been gradually improving since the 1960s. We also found that leg power AND abdominal strength It improved around 2000 and then declined.

So it looks like today’s kids have better grip strength than their parents and grandparents did when they were kids. Their leg strength and abdominal endurance are better than their grandparents’, but the same or worse than their parents’.

What’s the cause?

To explain these findings, our research team looked at several nationwide trends in each country, including trends in muscle fitness, physical activity levels, body weight, and income inequality.

We found no significant associations between trends in muscle fitness and trends in body size or income inequality. However, our study found that countries with the largest declines in physical activity levels also had the largest declines in leg power and abdominal endurance. For example, physical activity levels and abdominal strength have recently decreased in children from Slovakia, Switzerland and the UK. On the other hand, both have recently increased in children from Poland, Slovenia and Spain.

This suggests that children’s muscle fitness could be improved by increasing their levels of physical activity, such as if they were to meet the target set by the US government recommended physical activity guidelinesFor school-age children and adolescents, this includes 60 minutes or more per day of moderate to vigorous-intensity aerobic activity, plus muscle- and bone-strengthening activity at least three times a week.

This is especially critical during the COVID-19 pandemic, as lockdowns appear to drastically reduce children’s fitness levels. For example, The physical fitness level of Slovenian children dropped by 13% to its lowest level in 30 years after just two months of lockdown.

Children benefit from muscle conditioning in a variety of ways

A growing body of research suggests that children of all ages can benefit from appropriately supervised resistance training. A recent review of research on resistance training among children and adolescents has been found to improve muscle fitness, body composition, athletic performance, confidence, and self-esteem. Building muscle fitness requires at least three sessions per week of more than 30 minutes and consistent weight gain.

Although parents may fear that these types of activities are hazardous for their growing children, research also shows that participation in a properly supervised endurance training program does not stunt children’s growth or damage developing growth cartilage.

Improving muscle fitness makes it easier for any child to move, lift, and play sports. Our research suggests that resistance training may be particularly beneficial for overweight and obese teens who may not want or be able to do aerobic exercise. In another study we published in 2014,We found that six months of supervised resistance training made overweight and obese adolescent boys stronger and more confident during exercise.

What can children do to improve their muscle fitness?

Muscles become bigger and stronger by doing weighted or “resistance” exercises. These are exercises that cause a muscle or group of muscles to contract against an external resistance, such as a barbell, an exercise band, or your own body weight.

[Over 100,000 readers rely on The Conversation’s newsletter to understand the world. Sign up today.]

Although often performed in the gym, resistance training can be done anywhere, using a variety of activities and equipment. Jumping, climbing on playground equipment, push-ups, squats, lifting weights, and yoga are all weight-bearing activities.

As muscle fitness improves, children can try to enhance the duration or difficulty of their favorite physical activity, or do it more often.