Exercise throughout the lifespan

Text pages 639-650

Lifespan

Infants Children Adolescents- Puberty Adults Aging

Infants

How much exercise do babies need?

Parents are often concerned about the amount of exercise they should engage their baby in on order to enable successful motor development

The response is generally that play, cuddling, feeding, bathing etc is enough activity for a normal baby, and that there are so many different rates of development, there is no need to be concerned about their baby being “normal”

Recommended activities for Infants (Birth to 12 months) Engage your infant in some activity every day. This includes setting up

safe areas for the infant to play in, playing games with them, and carrying them to different environments to explore. Do not keep infants in baby seats or other restrictive settings for long periods of time.

To encourage your infant to be active, try the following: Lay your infant on a blanket on the floor with a few toys Provide brightly coloured, easy-to-grasp toys that can be squeezed or

have different textures to encourage reaching and grasping Place the infant on his tummy facing you, encourage him to lift his head

and kick his legs When the baby is learning to roll over, hold a favourite toy just out of

reach to motivate him to keep trying Play peek-a-boo or patty-cake; help move your child's hands so she

learns the motions Carry the child to a new environment, set her down, and let her explore

(be sure the area is baby-proofed)

Recommended activities for Toddlers (12 to 36 months) As walking skills progress, toddlers have a seemingly unending supply of

energy. Encourage them to use it all! Toddlers should accumulate at least 30 minutes of structured physical activity each day. Do not keep toddlers in baby seats or otherwise inactive for long periods of time.

Try the following: Bounce, throw, and chase balls to develop hand-eye coordination (use soft balls that

won't break anything) Dance to music and follow-along songs (think: Hokey-Pokey) to promote body

awareness and balance Play Simon Says and Follow the Leader Provide safe, sturdy objects to ride, push, pull, balance on, and climb Make chores into games that kids can help with, for example:

During dinner preparation, have him carry something that won't break or spill to the table On laundry day, have her throw her dirty clothes into the laundry basket

Encourage stair climbing, which develops leg muscles and coordination, but do so only on carpeted steps with an adult right behind to prevent falls

Recommended activities for Preschoolers (3 to 5 years) As kids gain more strength and balance, it is easier for them to

accumulate the recommended minimum of one hour of physical activity each day. Some suggestions:

To promote balance, help the child walk along a line on the ground, or along a sidewalk curb when there are no cars around

Lay out objects to create a maze or tell a child to run around a tree and back, providing vigorous exercise plus mastering turns and balance

Around age 3, children learn to hop and are ready for hopscotch; draw paths that require the child to hop first on one foot, then the other. This promotes balance and strengthens leg muscles

Around age 4, kids learn to skip; practice skipping with them across the yard, or work it into a game of Follow the Leader

Provide safe objects to ride, push, pull, balance on, and climb Emphasize fun, not competition. Preschoolers lack the social and

cognitive development for organized team sports, which can leave them frustrated and block later interest in sports.

Children

The impact of growth and potential for sports conditioning

BoysGirls

Peak height velocity

Decelerated growth

Adolescent growth spurt

Deceleratedgrowth

Accelerated growth

Note the sex differences here

Growth

Boys and girls of the same age are generally similar in terms of height, weight, strength etc until puberty

The increase in size over childhood is the most important factor in determining the changes in their response to exercise Biological age may not parallel chronological age

Increases in size

In females Muscle mass increases 7 kg 23 kg % Body fat increases 16% 23%

In males, between the ages of 6 and 16 Lungs grow which increases total lung capacity

from 1937 5685 ml Heart grows in weight from 95g to 258 g Muscle mass increases

Aerobic factors Heart rates in children may reach 220 or even 225

before puberty, but tend to fall to around 200 in their late teens, so the coach should not worry on finding such high rates in exercising youngsters.

Children also breathe faster than adults, reaching 60 breaths/minute compared to 40/minute in adults doing equivalent exercise.

Compared to adults, children need to breathe more air to get the same amount of oxygen, i.e. their ‘ventilatory equivalent for oxygen’ (the number of litres of air to gain one litre of oxygen) is higher. This is wasteful of energy and body water (in the breath).

Energy systems Muscular concentration of ATP is similar in children, adolescents,

and adults The total reservoir of high energy phosphates is lower in children

because of their smaller muscle mass relative to structure. In exercise, depletion of high-energy phosphates occurs at

similar rates for children and adults. Boys' anaerobic performance increases with age from childhood

to adulthood. When related to body mass, the anaerobic performance of an 8 year-old boy is about 70% of an 11 year-old.

Girls' anaerobic performance also increases from childhood but appears to reach a maximum value during the teen years.

Anaerobic Capacity

Children have a distinctly lower anaerobic capacity compared to adolescents and adults.

Low levels of male reproductive hormones

low glycolytic capacity

lower lactate production

decreased buffer capacity

decreased rates of glycolgenolysis

lower lactate threshold

Thermoregulation

Children are not as effective in dissipating heat as adults:

produce more heat relative to body mass

lower sweat rates at rest and during exercise

greater energy expenditure during exercise

lower cardiac output relative to metabolic intensity

rely more on convective heat loss than evaporative cooling

Training Considerations

Even when controlling for maturation, it is clear that children can adapt to endurance training

Physiologic changes in children resulting from training and growth and maturation

Characteristic ChangeHeart rate, resting and submaximal Decrease

Arterial blood pressure, maximal Increase

Minute ventilation, maximal Increase

Oxygen uptake, maximal (L/min) Increase

Blood and muscle lactate, maximal Increase

Muscular strength Increase

Anaerobic power (Watts/kg) Increase

Benefits of exercise for children

Caloric balance Stimulates growth hormones

Growth Hormone Mechanical stresses (overload) triggers

musculoskeletal growth Hypertrophy of muscle Metabolic efficiency

Adolescents

Pubertal growth spurt

Growth and DevelopmentThe most rapid increase in height and weight occurs during puberty, and is referred to as the pubertal growth spurt

The most rapid rate of growth occurs during the adolescent years, and is referred to as the peak height velocity (PHV).

Girls tend to be slightly taller and heavier than boys from years 2-10, and PHV occurs 2 years earlier in girls than boys

Assessment of MaturationAs children mature at different rates, chronological age is not a good gauge of physical development or maturation.

Tanner stage of sexual maturation

STAGE Description1 Absence of development of any secondary sex characterstics

2 Initial elevation of breast in girls and enlargement of thegenitals in boys ; For both sexes, pubic hair begins to grow

3 & 4 Pubic hair becomes coarser and begins to curlRelative enlargement of larynx in boysIncrease in pelvic diameter begins in girls

5 Adult maturation; Mature spermatozoa are present in males ;Full reproductivity in womenAxially hair is present, and sweat and sebaceous glands arevery active in both sexes

Fat free mass

One of the major changes during puberty is the increase in body fat in females

Muscle mass represents 53% of the weight of an average 17 year old male; but 42% of that of a 17 year old female

This is a result of the respective sex hormones

Aerobic capacity Muscular concentration of ATP is similar in adolescents, and

adults Adolescents have significantly lower muscle glycogen stores

than adults and also are less capable of generating ATP. Young people do not have the same capabilities as adults to

perform strenuous exercise for periods between 10 and 60 seconds.

Gender-related differences are minimal prior to puberty. However, during adolescence boys become significantly better anaerobic performers than girls, an advantage that is retained for the remaining years.

Laboratory Measures Of

Physical Fitness In ChildrenAerobic Capacity

Male Female

Note altered trends when body mass is considered

Strength training

Resistance training in prepubertal subjects tends to cause increases in strength without increases in muscle size

30-40% gains in strength following an 8-12 week program (Payne, Morrow, Johnson., & Dalton, 1997)

Resistance training effects can be found in young, adult, and aged populations.

Girls have the potential to improve more than boys. [They start from a lower status.]

Precautions with strength training Epiphyseal injuries- epiphyseal plate (point from

which bones grow) fuses resulting in stunted growth as bones cannot grow anymore

Adolescents should avoid competitive weight lifting, power lifting, body building, and maximal lifts until they reach physical and skeletal maturity (~ 17 females and 18.5 males)

These are mostly caused by maximal lifts, improper technique and improper supervision

Adolescents should use lower weights and higher reps rather than 3 or 4 reps of a 80-100% max weight

Adults

The majority of the acute and chronic adaptations to exercise

that we have studies apply to adults 20-50 years of age

Aerobic capacity

Vo2 max decreases by 8-10% per decade after 30

Those that exercise can halve the usual decline that is expected with age, ie. 4-5% per decade loss of vo2 max

Mid life changes Menopause- cessation of menstruation in women –

av age = 51-Regular exercise during menopause is known to decrease the frequency and severity of hot flushes

Andropause may or may not actually exist as a clinical phenomenon. Its proponents claim it is a biological change experienced by men during their mid-life steady age-related decline in testosterone levels in men, since a man's reproductive systems gradually decline with age, but do not stop working altogether in mid-life, as a woman's do.

Older Adults

Defining AgingA manifestation of biological events that occur over time.

The natural life span is suggested to be the age of 85.

Life expectancy is the average, statistically predicted length of life for an individual.

71 years for men of developed countries

78 years for women of developed countries

It is estimated that in the near future 50% of all deaths will occur after the age of 80 years

Successful AgingSuccessful Aging

Requires maintenance of enhanced: Physiologic function Physical fitness

Components of successful aging Physical health Spirituality Emotional and educational health Social satisfaction

Physical Activity and AgingPhysical Activity and Aging Physical activity reduces the impact that “normal

aging” has on: Blood pressure- normal aging= BP increases, especially

with artherosclerosis Body composition- 10% reduction in BMR up to age 65

and further 10% after. This is what leads to an increase in body fat if portion sizes/ exercises are not altered

Muscle mass- normally a 3-5% loss in each decade after 25. resistance exercise limits loss of muscle and strength

Bone mass- normally decreases In females -2-3% decline after 30 = 20% by 65; 30% at 80 In males - 1% per year after 50 = 10% by 65, 20% by 80but the decrease can be limited by resistance exercise

Effects of exercise and age on select body systems, simplified

Body System Exercise Aging

CirculatoryVO2max Increase Decrease

HRmax Increase Decrease

Cardiac Output, maximal Increase Decrease

Vascular resistance Decrease Increase

Blood pressure Same or Decrease Increase

Blood ComponentsTotal cholesterol ? Increase

Triglycerides Decrease Increase

LDL cholesterol ? Increase ?

HDL cholesterol Increase Decrease ?

Effects of exercise and age on select body systems, cont’d

Body System Exercise Aging

MusckuloskeletalMuscular strength Increase Decrease

Muscular endurance Increase Unchanged

Flexibility Increase Decrease

Bone mineral Increase Decrease

Lean body mass Increase Decrease

Adipose tissue Decrease Increase

Regulatory systemsBasal metabolic rate Increase Decrease

Sleep Increase ? Decrease

Anxiety/Depression Decrease? Increase ?

Cognitive functioning Increase Decrease ?

Decreased VO2max

Aging associated decreases in maximal cardio-respiratory endurance

Cardiovascular function

Cardiac output

Blood volume Stroke volume

ejection fraction

ventricular filling

myocardial compliance and elasticity

Ventilatory and pulmonary function

VE/Q mismatch

Work of breathing

Respiratory muscle strength/endurance

Lung compliance and elasticity

Closing volume

Maximal Oxygen Uptake (VO2max)

VO2max decreases 8-10%/decade after age 30

VO2max can be equally improved with training in the elderly as it is in youth

Pulmonary Changes with Age

Structural & functional changes to the pulmonary system with age

Body System Aging

Structural changesAlveolar elastic recoil Decrease

Respiratory muscle strength Decrease

Alveolar surface area Decrease

Pulmonary blood volume Decrease

Residual lung volume Increase

Functional changesVEmax Decrease

Expiratory flow rate Decrease

Maximal voluntary ventilation (MVV) Decrease

Vital capacity Decrease

Adolescent male

Adolescent female

30 year old - active

30 year old - inactive

% Decrease in bone mineral

Musculoskeletal System

By age 90, 32% of women and

17% of men will have sustained a

hip fracture.

Regular physical activity can

decrease the rate of age-related

bone mineral loss

Muscle Trainability Among the ElderlyMuscle Trainability Among the Elderly Regular exercise

training retains body protein and blunts the loss of muscle mass and strength with aging

Older people are equally as responsive to resistance training as young people

Aging and Joint FlexibilityAging and Joint Flexibility

With advancing age, connective tissue becomes stiffer and more rigid, which reduces joint flexibility

Regularly moving joints through their full range of motion increases flexibility by 20 to 50%

Osteoarthritis is common degenerative joint disease found among older adults. It is caused by the wearing down of cartilage which results in 2 bones rubbing against each other pain and inflammation

Aging and Endocrine Changes Aging and Endocrine Changes Endocrine function changes with age,

particularly the pituitary, pancreas, adrenal, and thyroid glands (reduced thyroxine is responsible for the lowered BMR)

Impaired glucose tolerance means that body is not able to release right amount of insulin to deal with blood glucose levels and coordinate the storage/usage glucose/glycogen. This can lead to type 2 diabetes

Aging and Cardiovascular FunctionAging and Cardiovascular Function Maximal oxygen uptake ( O2max) declines steadily

after the age of 20 A slower rate of decline occurs for individuals who

maintain an active lifestyle that includes regular aerobic exercise training

Physical activity, however, does not entirely offset aging’s effect on O2maxV

V

Aging Response to Exercise TrainingAging Response to Exercise Training

For the healthy elderly, exercise training enhances the heart’s capacity to pump blood and increases aerobic capacity to the same degree as in younger adults

Summary

Although exercise is beneficial throughout the lifespan there are considerations for the safety and

effectiveness of exercise at different life stages