The Physical Activity Mismatch

What is an overview of the physical activity mismatch?

1. Humans used to be highly physically active due to necessity

2. Humans used to be lazy after a days work to not expend too much energy

3. Humans have evolved to be lazy

What must you do to a system in order to maintain it?

Stress it (eg. cardiovascular system through exercise)

What kind of physical activity are humans adapted for?

Physical activity that is endurance based rather than power for a range of unusual and sometimes unique physical activities:

• Long-distance walking and running in the heat

• Digging

• Carrying

• Throwing projectiles both hard and fast

How many generations ago was everyone a hunter-gatherer?

600

How mnay miles on average did hunter-gatherers have to cover?

5-10 miles per day in order to cover enough area. This came with adaptations for long distance walking (ie. long legs, modern pelvis, and large joints)

How much of hunter-gatherer diet came from hunter meat?

30% of diet, so hymans were adapted for long distance running to chase after prey, as well as adapted to be good at throwing

Why did hunter-gatherers have to cover large areas of land each day?

Gathering food everyday would slowly deplete areas of food as it doesn’t grow back quickly enough, so foods like nuts, fruits and berries are all sparse so large areas of land would need to be covered to gather enough food

What were the adaptations of hunter-gatherers?

Longer legs, bigger joints, and more efficient hip comlex allowing humans to travel long distances

Are humans endurance runners?

Yes, humans evolved as endurance runners, capable of travelling long distances efficiently. This was crucial for persistance hunting and migration. Humans have therefore adapted to be able to sweat to reduce internal heat, and become bipedal which is largely more energy efficient than quadrupedalism

Can humans carry and lift?

Yes, humans skeletal and muscular structures allows them to carry loads over long distances, essential for foraging and survival

What is a natural response to needing to conserve energy?

The desire to reduce caloric output

What is the difference between people in the past and today?

Previously people had to be physically active (everday activity) to survive, whereas, today people don’t have t but they can choose to through exercise (voluntary)

What is the energy allocation theory?

It indiciates that minimising effort is actually adaptive in conditions with limited food (back in the day you could not fully control caloric intake, but you could control caloric expenditure as you want to save energy for when you need it like catching prey or running from a predator)

Why were humans were selected to avoid unnecessary exertion?

Because energy from food was limited (most anatomical/physiological systems evolved to require stimuli from physical activity to adjust capacity to demand)

What does natural selection act on?

Reproductive success (since organisms must trade off limited energy resources, natural selection will always favour mechanisms that trade off energy in ways that favour reproduction)

What are the body's physiology and anatomy adapted to respond to?

Stresses generated by physical activity to generate enough but not too much capacity

What did females need to do?

As females were most always pregnant or nursing, they also needed to supply food to both infants and children who are unable to forage their own food, and so needed to have an increased intake of energy and lower levels of exertion

How can exercise be promoted?

Because humans evolved to be active for play or necessity, efforts to promote exercise will require altering environments in ways that nudge or even compel people to be active and to make exercise fun

How does the physical activity mismatch impact brain function?

It has a negative impact on brain function: chronic inactivity leads to reduced brain capacity to save energy which leads to age related atrophy

What does the physical activity mismatch lead to an increased risk of?

Chronic diseases, type 2 diabetes, and certain cancers

How does the physical activity mismatch impact mental health?

Results in poorer mental health, such as increased risk of depression, anxiety, and sleep problems

What happens if not using energy within the musculoskeletal or cardiovascular system?

The energy will be put towards the reproductive system

What happens if a system is not used enough?

The energy it intakes will decrease and this has the potential to decrease enough to become a potential health risk (except the reproductive system)

How can most issues of the health consequences of the physical activity mismatch be fixed?

By having a good exercise regime and a high protein diet

How are chimpanzees different to humans?

• They are more than twice as strong

• Their leg muscles are dominated by fast-twitch fibres

• They rarely sprint

• They cannot cool effectively through sweating so are better at power over endurance