LO6 of Unit 1 – Life course of the Musculoskeletal System (2021)

Life course of the Musculoskeletal System

Learning outcomes
By the end of this section, you will be able to:

Describe the life course of the musculoskeletal system to include:

  • Young people in the 13-18 age range
  • Antenatal and postnatal women
  • Older adults (50 plus)

Effects of exercise on the musculoskeletal system

Activity is vital to muscle and bone health and the early years are an ideal time to develop these. A whopping 90% of bone mass is created during the first two decades of life, so regular activity is essential to maximise bone density. Low bone density in adults is a risk factor for osteoporosis and the complications that go along with it.

Muscle strength accelerates for both boys and girls post-puberty as part of growth. However, strength is hugely influenced by exercise, particularly by lifting weights.

However, regardless of age, all individuals should regularly perform weight-bearing, weightlifting, and high-impact activities as long as the type of activity is appropriate for their stage of development, skill level, and physical condition and experience.


Bone mass changes graph

Children and adolescents

Many changes occur in the body, from childhood to adulthood. During the growth spurt, growth hormones, testosterone (in males) and oestrogen (in females) cause a change in body shape. These changes can occur rapidly, and trainers should be aware of how growth and development are influenced by exercise or physical activity.

Physical activity has been shown to positively influence bone mass development, muscle strength, ligament and tendon strength and body composition (to include reducing fat mass). It has also been shown to improve mood and self-esteem.

However, there is a common myth that high impact and resistance training activities stunt growth and halt natural development due to overloading the vulnerable and weaker bone points.

The early years are the ideal time to develop bone health as 90% of bone mass is created during the first two decades of life. As low bone density in adults is a risk factor for osteoporosis, weight-bearing and resistance training activities in children have been shown to have a positive effect on bone density and encourage their future health. However, some caution is advised, and adult loading and training programmes are not suitable for the developing child, who will generally have low skill levels and be emotionally under-developed.


Active adolescents

Exercise implications for children and adolescents

  1. There may be a decrease in balance and coordination due to rapid increases in limb length
  2. Osgood Schlatter’s disease (pain in and around the patella tendon) and Sever’s disease (pain in and around the heel)
  3. is common in growing children and adolescents. Reduce or avoid activity (high-impact activity in particular), affecting those sites and seek a medical opinion
  4. Develop sound movement patterns before increasing training load and volume

Antenatal and postnatal women

Pregnancy is a time of significant change. Although it is doubtful a pregnant woman will take up exercise if she is not already participating in an exercise programme, trainers need to be aware that activities need to be adjusted to accommodate the changes during pregnancy.

The following changes will occur:

  1. In the first trimester (0-3 months) it is normal for blood pressure to drop as blood vessels dilate to prepare the body for an increase in blood volume during the second and third trimesters. Therefore, the woman may experience dizzy spells, especially when rising from the floor.
  2. Relaxin is a hormone released to increase ligaments’ laxity around joints (mostly the pelvis), reducing joint stability (ante-natal and postnatal).
  3. There will be changes in posture as the baby grows and the centre of mass moves forward, resulting in an increased lumbar curve.
  4. The abdominis will separate during the later stages of pregnancy, along the linea alba.
  5. There will be increased stress on the pelvic floor muscles due to the baby’s weight, resulting in stress incontinence.


Exercise implications during pregnancy:

  • Lower impact and intensity
  • Lower resistance
  • Take care with abdominal work
  • Maintain current fitness levels rather than improving them
  • Avoid developmental stretching
  • Avoid supine positions at later stages of pregnancy
  • Focus on maintaining posture
  • Avoid heavy abdominal work, especially in the later stages

Exercise implications after pregnancy

Women can return to exercise after their midwife check. This usually occurs at 6-8 weeks with normal birth. For caesarean sections, it usually takes place after 12 weeks.

Older adults (50 plus)

Getting older is inevitable; however, scientists now understand the ageing process and the benefits of maintaining a lifelong exercise habit. An increasing body of evidence supports the theory that participation in a regular exercise program positively affects the musculoskeletal system to reduce or prevent several conditions associated with ageing. 

These include:

  • Osteoporosis/osteoarthritis
  • Changes in posture
  • Risk of falls – kyphosis
  • Reduced bone resilience
  • A decrease in muscle mass (atrophy) and strength
  • Increased risk of fractures
  • Reduced joint stability
  • Reduced synovial fluid, calcification of cartilage
  • Reduced neurological connections
  • Considerations for other medical conditions (congenital heart disease etc.)
  • Weakened pelvic floor


Exercise implications for older populations

  • The age and level of fitness should be considered, and any existing medical conditions.
  • Lower intensity
  • Lower impact
  • Promote mobility and posture
  • Strengthen areas susceptible to fracture (e.g. wrist, hip and spine)
  • Use slower movements

Age related loss in strength vs activity

Strength training can help offset age-related loss of muscle mass, which decreases by approximately 15% per decade in the sixth and seventh decade. Strength training is also suitable for maintaining bone density, showing a decline in both males and females from the fourth decade. After the fifth and sixth decade, women are significantly affected following the menopause and generally experience a more significant bone loss than men.

Aerobic and endurance training can help maintain body weight and improve various aspects of heart and lung function. Both strength and aerobic exercise can positively affect health and reduce disease likelihood.