Physical development during middle childhood is generally slow and steady, with changes in height and weight, muscle mass, gross and fine motor skills, and even changes to the brain.

9.2.1 Height and Weight Changes

During middle childhood, children experience significant height changes, but the rate of growth is slower than during infancy and early childhood. On average, children grow about 2-3 inches (5-7.5 cm) per year during middle childhood. Between ages 6 and 12, children typically grow an average of 2-3 inches per year, but this can vary depending on factors such as genetics, nutrition, and overall health. Girls generally have a growth spurt earlier than boys and may experience a growth spurt around age 9 or 10, while boys may not have their growth spurt until age 11 or 12. Girls tend to have their growth spurt before boys during middle childhood due to several factors, including differences in hormonal activity and genetics. One important factor is the hormone estrogen, which is responsible for female sexual development. Estrogen stimulates the growth of long bones, which contributes to height. Girls typically begin producing estrogen earlier than boys, which means they enter their growth spurt earlier.

Children experience significant changes in weight as they grow and develop. On average, children gain about 4-7 pounds (1.8-3.2 kg) per year during this stage of development. Factors such as genetics, nutrition, and physical activity levels can all influence weight changes during middle childhood. Children who are genetically predisposed to be heavier may gain more weight than their peers, even with a healthy diet and regular exercise. Similarly, children who have a poor diet or who are not physically active enough may be at risk for weight gain and related health problems. Some weight gain is normal and necessary during middle childhood, as children need to gain weight to support their growing bodies and developing organs. Additionally, weight gain during middle childhood is not always an indicator of future weight problems or obesity, as many children grow out of their baby fat as they mature. Body mass index (BMI) is a common measurement used to assess weight status in children and adults. BMI takes into account both height and weight and provides a numerical score that can help determine whether a child is underweight, at a healthy weight, overweight, or obese. In middle childhood, a healthy BMI range can vary depending on the child’s age and sex. The Centers for Disease Control and Prevention (CDC) provides BMI-for-age growth charts that can help healthcare providers and parents determine a child’s weight status. For example, a BMI between the 5th and 85th percentiles is considered healthy or “normal” for most children. A BMI between the 85th and 95th percentiles is considered overweight, while a BMI at or above the 95th percentile is considered obese.

BMI is just one tool used to assess weight status, and it may not always be accurate for all children. BMI is calculated based on height and weight and does not take into account body composition or distribution of body fat. As a result, individuals with high muscle mass, such as athletes, may have a higher BMI even though they are not overweight or obese. Conversely, individuals with a low muscle mass and high body fat may have a lower BMI, even though they are at risk for health problems related to excess body fat. Children who are particularly muscular or who have a larger-than-average bone structure may have a higher BMI without being overweight or obese. Additionally, other factors such as nutrition, physical activity, and overall health should also be taken into account when assessing a child’s weight status.

Though BMI is a commonly accepted tool for assessing weight as a health indicator, it has been criticized for its cultural and gender bias (e.g., Gutin, 2021). BMI was originally developed based on data from white populations, mostly middle-class men, and may not accurately reflect body composition or health risks in individuals of other ethnicities or races. BMI may not account for age and sex differences. The healthy BMI range can vary depending on age and sex, with children and adolescents having different healthy BMI ranges than adults. Therefore, using a single BMI cutoff point for all individuals may not be appropriate. In addition, BMI may not account for changes in body composition over time, as it may not be sensitive enough to detect changes in body composition that occur during periods of growth or changes in physical activity levels. As a result, children and adolescents who are experiencing changes in body composition due to growth and development may be misclassified as overweight or obese based on their BMI.

Parents and caregivers can help children maintain a healthy weight by encouraging healthy eating habits, regular physical activity, and positive body image. Regular check-ups with a pediatrician or healthcare provider can also help ensure that children are growing and developing normally.

9.2.2 Bone and Muscle Mass

As bones lengthen and broaden, and muscles strengthen, many children want to engage in strenuous physical activity and can participate for longer periods of time. In addition, the rate of growth for the extremities is faster than for the trunk, which results in more adult-like proportions. Long-bone growth stretches muscles and ligaments, which results in many children experiencing growing pains.

Muscle mass development is an important aspect of physical development during middle childhood. During this stage, children experience significant increases in muscle mass and strength as they become more physically active and engage in sports and other physical activities. Regular physical activity is essential for muscle development during middle childhood. Activities such as running, jumping, and climbing help to build muscle and improve strength, coordination, and balance. Strength training exercises, such as push-ups, sit-ups, and resistance exercises, can also be beneficial for building muscle mass in older children. Nutrition also plays a key role in muscle development during middle childhood. Children need adequate protein, carbohydrates, and other nutrients to support muscle growth and repair. A healthy, balanced diet that includes lean protein sources, such as chicken, fish, and beans, as well as whole grains, fruits, and vegetables, can help ensure that children have the nutrients they need for optimal muscle development.

Boys and girls typically have different amounts of muscle mass during middle childhood due to differences in hormonal activity and genetics. During this stage, boys tend to have higher levels of testosterone, which is a hormone that promotes muscle growth and development. As a result, boys typically have more muscle mass and greater muscle strength than girls. However, individual differences can also play a role in muscle development. Some girls may have more muscle mass and strength than boys of the same age, particularly if they are physically active and engage in strength training exercises.

Additionally, cultural and societal factors can also influence muscle development in boys and girls. For example, in some cultures, boys may be encouraged to engage in physical activities that promote muscle growth, while girls may be discouraged from such activities. These factors can contribute to gender differences in muscle mass and strength during middle childhood and beyond. Overall, while there are some gender differences in muscle mass during middle childhood, individual factors such as physical activity and nutrition can also play a significant role.

Figure 9.1. The physical growth of a typical boy at ages 5, 8 and 10.

9.2.3 Motor Development

Children between ages 6–9 show significant improvement in their motor skills. This growth allows children to gain greater control over the movement of their bodies, mastering many gross and fine motor skills that were beyond that of the younger child.

9.2.3.1 Gross Motor Skills

Gross motor skills refer to the ability to use large muscles of the body for movement and physical activities. During middle childhood, there is a significant development in gross motor skills as children become more physically active and participate in organized sports and activities. Some of the gross motor skills that children develop during middle childhood include:

• Running and jumping: Children’s ability to run and jump becomes more coordinated and efficient during middle childhood. They are able to run faster, jump higher and land with more stability.
• Climbing and balancing: Children become more skilled at climbing and balancing on objects such as monkey bars, trees, or balance beams. They develop better coordination and can perform more complex movements.
• Throwing and catching: Children develop the ability to throw and catch balls with greater accuracy and force. They can also track the trajectory of a ball more effectively, which helps them anticipate its movement and make better catches.
• Kicking and striking: Children become better at kicking and striking objects such as balls or shuttlecocks with greater accuracy and force. They develop more precise and coordinated movements, which allows them to perform better in sports such as soccer or tennis.
• Coordination and agility: Children’s movements become more fluid and coordinated, allowing them to perform complex movements with greater ease. They become more agile and can change direction quickly, which helps them in sports such as basketball or hockey.

Overall, the development of gross motor skills during middle childhood is crucial for children’s physical development and overall health. It enables them to participate in a range of activities and sports, promotes a healthy lifestyle and helps build self-confidence and self-esteem. Sports and extracurricular activities may become a part of the lives of children during middle childhood due to their physical growth and capabilities. Children’s gross motor skills develop at different rates, and some children may struggle more than others. However, with practice and encouragement, children can improve their gross motor skills and build confidence in their physical abilities. Parents and caregivers can support their children’s gross motor development by providing them with opportunities to engage in physical activity, playing with them outside, and enrolling them in sports or recreational activities.

9.2.3.2 Fine Motor Skills

Fine motor skills involve the use of small muscles in the hands and fingers for tasks that require precision and control, such as writing, drawing, cutting, and manipulating small objects. During middle childhood, there is a significant development in fine motor skills as children become more adept at using their hands and fingers for complex tasks. Some of the fine motor skills that children develop during middle childhood include:

• Writing and drawing: Children’s ability to write and draw becomes more refined and precise during middle childhood. They develop better control over their hand movements and can produce smaller and more intricate shapes and lines.
• Cutting and pasting: Children become more skilled at using scissors and glue to create art projects and crafts. They develop better hand-eye coordination and can cut and paste with greater accuracy and precision.
• Manipulating small objects: Children become better at manipulating small objects such as beads, buttons, and coins. They develop better dexterity and can perform more complex movements with their fingers.
• Typing and using digital devices: As technology becomes more prevalent in daily life, children develop fine motor skills for using digital devices such as computers, tablets, and smartphones. They become more adept at typing, swiping, and tapping with their fingers.

Overall, the development of fine motor skills during middle childhood is crucial for children’s academic, social, and emotional development. It enables them to perform complex tasks such as writing, drawing, and using technology, which are important for academic success. It also allows them to engage in creative activities and hobbies, which can promote self-expression and emotional well-being.

9.2.4 Physical Activity

Recess is a time for free play and physical education (PE) is a structured program that teaches skills, rules, and games. Both are a big part of physical fitness for school-age children. For many children, PE and recess are the key component in introducing children to sports.

9.2.4.1 Physical education classes

Physical education (PE) is an important component of elementary and middle school education. It promotes physical fitness, healthy habits, and socialization skills, and helps children develop an appreciation for physical activity that they can carry into adulthood. In elementary school, PE programs typically focus on developing fundamental movement skills, such as running, jumping, throwing, catching, and balancing. These skills provide a foundation for more complex physical activities later in life. PE classes also introduce students to team sports, such as soccer, basketball, and volleyball, and may include individual activities like gymnastics or dance. Middle school PE programs build on the fundamental skills developed in elementary school and introduce students to more advanced concepts and activities. For example, students may learn about sportsmanship, teamwork, and strategy in team sports, or may focus on improving their cardiovascular endurance through running, swimming, or cycling. PE classes in middle school may also include health and wellness education, covering topics such as nutrition, stress management, and the risks associated with substance abuse.

After years of schools cutting back on recess and PE programs, there has been a turn around, prompted by concerns over childhood obesity and the related health issues. Despite these changes, as of 2016 only the state of Oregon and the District of Columbia meet PE guidelines of a minimum of 150 minutes per week of physical activity in elementary school and 225 minutes in middle school (SPARC, 2016).

9.2.4.2 Recess

Recess is an essential part of elementary school education as it provides many benefits for students’ physical, social, emotional, and cognitive development.

Physical activity. Recess provides an opportunity for students to engage in physical activities such as running, jumping, and playing games, which promotes good health, physical fitness, and reduces the risk of obesity. During recess, children interact with each other, make friends, learn social skills, and practice communication, negotiation, and conflict resolution skills.

Emotional regulation. Recess allows students to release their energy, reduce stress, and promote emotional regulation. By having a break from academic activities, students can recharge and refocus their attention.

Cognitive development. Recess can have a positive impact on academic performance, as it allows students to improve their attention and concentration, cognitive flexibility, and problem-solving skills.

Creativity and imagination. Recess provides children with an opportunity to use their imagination, explore their surroundings, and engage in creative and unstructured play.

Overall, recess is a critical part of elementary school education that supports children’s physical, social, emotional, and cognitive well-being.

9.2.4.3 Organized sports

Many parents introduce children to organized sports in middle childhood. For example, nearly 3 million children play soccer in the United States (US Youth Soccer, 2022). This activity promises to help children build social skills, improve athletically, and learn a sense of competition. Youth sports can provide a range of benefits that contribute to a child’s physical, social, and emotional development. There are numerous benefits to youth sports.

Participation in sports can improve a child’s overall physical health by promoting regular exercise, improving motor skills, and developing endurance and strength (Eime et al., 2013). This can lead to reduced risk of obesity, heart disease, and other health problems. Team sports provide children with opportunities to develop important social skills such as communication, collaboration, and leadership. They can also learn how to manage their emotions, build resilience, and work through challenges. Success in sports can improve a child’s self-esteem and confidence, leading to better academic performance and overall well-being. Academic benefits: Studies have shown that students who participate in sports often perform better academically, as they learn to manage their time and prioritize responsibilities. Participation in sports can teach children important life skills such as teamwork, sportsmanship, discipline, and goal-setting. These skills can be applied in other areas of their lives, including school, work, and personal relationships. Participating in sports can be a fun and enjoyable experience for children, which can contribute to their overall well-being and happiness.

While organized sports can provide numerous benefits for children, there are also some challenges that can arise. The pressure to win can become overwhelming for both children and parents. This can lead to an unhealthy focus on winning at all costs, which can negatively impact a child’s self-esteem and enjoyment of the sport (Brenner et al., 2019). Participating in sports comes with inherent physical risks, including the potential for injuries such as sprains, strains, and fractures. It’s important for children to learn proper technique and safety precautions, and for coaches to prioritize player safety. When children participate in sports at a highly competitive level, they can experience burnout due to the intense pressure and commitment required. This can lead to physical and emotional exhaustion and a loss of enjoyment in the sport. Sports can be dominated by certain demographics, which can lead to a lack of diversity and inclusion. This can limit opportunities for children from different backgrounds to participate and can create a culture of exclusion and discrimination.

It’s important for parents, coaches, and organizations to address these challenges and work to create positive and inclusive environments for children to participate in sports. This can involve prioritizing safety, reducing pressure to win, promoting diversity and inclusion, and ensuring that sports remain fun and enjoyable for all participants. Gender, poverty, location, ethnicity, and disability can limit opportunities to engage in sports. There are several strategies that can be used to increase equitable access to youth sports, including:

1. Financial assistance: Providing financial assistance can help to reduce the financial barriers that prevent some children from participating in sports. This can involve offering scholarships, reduced fees, or equipment loans to children from low-income families.
2. Community partnerships: Working with community organizations, local businesses, and government agencies can help to expand access to sports programs in underserved areas. This can involve building new facilities, offering transportation, and providing resources to support sports programs.
3. Inclusive policies: Developing inclusive policies that promote diversity and inclusion in all aspects of sports can help to reduce discrimination and bias. This can involve implementing policies that promote gender equity, racial and ethnic diversity, and accessibility for children with disabilities.
4. Volunteerism: Encouraging volunteerism can help to expand access to sports programs in underserved areas. This can involve recruiting and training volunteers to serve as coaches, mentors, and program leaders.
5. Awareness and education: Raising awareness and educating parents, children, and community members about the benefits of sports and the importance of equity can help to increase participation and support for sports programs. This can involve promoting the positive aspects of sports, sharing success stories, and addressing myths and misconceptions about sports.

Overall, increasing equitable access to youth sports requires a coordinated effort by parents, coaches, organizations, and communities. By working together and implementing strategies that prioritize inclusivity, we can help to ensure that all children have the opportunity to benefit from the positive aspects of sports.

9.2.5 The Secular Trend in Physical Growth

Did you know that men in the middle ages averaged about 5’6” in height? Over the last two centuries, the average height has increased. This gradual increase in physical growth refers to the gradual and continuous increase in body size and development observed over generations. This trend has been observed in many countries around the world and is thought to be driven by improvements in nutrition, healthcare, and living conditions.

The secular trend is most noticeable in the increase in height and weight of populations over time. For example, in the United States, the average height of men has increased by about 2 inches (5 cm) since the mid-19th century, and the average weight has increased by about 25 pounds (11 kg) since the 1960s. Other physical changes associated with the secular trend include earlier onset of puberty, longer limbs, and larger head circumference. These changes are thought to be due to improvements in nutrition and health during infancy and childhood, as well as improvements in maternal health and care during pregnancy. Overall, the secular trend in physical growth has important implications for public health and social policy, as it highlights the importance of continued improvements in nutrition, healthcare, and living conditions to support the healthy development of future generations.