Physical Activity and Health Related Outcomes Flashcards
What is the history of physical activity?
Claudius Galenus (Ad131) Greek Physician – On Hygiene – promoted his belief that everyone could benefit from exercise
Scientists and physicians in China & India recognised a link between physical activity and health over 5000 years ago
Scientific support for the belief that exercise could prevent or ameliorate disease did not emerge until 20th century
1940s London Bus Study (Jerry Morris & colleagues)
1950s cardiologist Paul Dudley White prescribed exercise as part of the treatment for people with coronary heart disease
1960s & 1970s popularised jogging and running led to exercise scientists to systematically explore the effects of various types, duration and intensity of endurance exercise on cardio-respiratory fitness
1980s onwards there has been a growing awareness of the contribution of moderate physical activity to health and fitness
What did the London Bus study find?
1940s London Bus Study was the first physical activity epidemiology study.
They measured active and inactive busmen and postal works and compared the CHD death.
It was found that busmen and postal workers who were inactive had a higher CHD death (rate per 1000)
Which chronic conditions is physical inactivity associated with?
- ischaemic heart disease
- diabetes
- osteoporosis
- some forms of cancer
- obesity
What are the health benefits of physical activity?
20-30% reduced risk of premature death
50% reduced risk of developing chronic diseases
Improve quality of life & independence in later life
Reduced obesity
Skeletal health and growth → less falls/ injuries in the older people
Increased psychological well-being
(Warbuton et al., 2006, Saxena et al., 2005)
Give an example of the evidence of physical activity health benefits.
- A study measured the average composite of 20 students’ brains taking the same test after sitting quietly or taking a 20 minute walk.
- -Increased blood flow to the brain
- Blood volume increases
- Blood flow is more “predictable”
- Small vessels grow – increase in number
- Brings O2, glucose, nutrients to brain cells, vital for cell health
- Blood washes away “metabolic wastes” such as “amyloid beta protein” (implicated in development of Alzheimers)
2011 Study of 16 women aged 60+:
Walking briskly 3-4x/ week, improved blood flow up to 15%; VO2 max – (the body’s maximum capacity to transport and use oxygen during exercise) increased about 13%, their blood pressure fell an average of 4%, and their heart rates decreased about 5%.
What is the link between evolution and exercise?
The relationship between the ability to obtain food, shelter, comfort, and the physical ability to obtain them through learning that has been hardwired into the brain’s circuitry.
In order to survive we had to use our brains to find and store food. We needed fuel to learn and learning to find a source of fuel. We needed to move! On average 11 km per day!
“That which we call thinking is the evolutionary internalization of movement.”
Neurophysiologist Rodolfo Llinas
As we evolved, our physical skills developed into abstract abilities to predict, sequence, estimate, plan, rehearse, observe, judge, correct mistakes, shift tactics, and remember everything we did in order to survive.
What happens when we exercise in the glands?
Hormones respond
Pituitary gland releases human growth hormone to increase production of bone, muscle, or connective tissue cells.
Pituitary gland regulates thyroid gland (increase heart rate and blood pressure, regulate body temperature & elevate “alertness” in brain to increase concentration and RT)
Pituitary gland regulates thyroid gland (increase heart rate and blood pressure, regulate body temperature & elevate “alertness” in brain to increase concentration and RT)
Adrenal glands secretes adrenaline (F&F; increases strength and frequency of heart contractions, speeds breakdown of stored carbs into glucose for muscle energy)
Adrenal glands secretes cortisol (increase in blood pressure, glucose, acts as anti-inflammatory agent [repairs tissues] curbs non-critical functions such as thirst, urine, hunger, & immune system)
What happens to the nerve cells when we exercise?
80% of the brain signals rely on two main neurotransmitters:
Glutamate - stirs up the activity and begins the cascade
GABA - locks the brain activity down
These two neurotransmitters begin the chemical sequence of brain activity that regulates all of our behaviour. In many cases they stimulate the release of many other neurotransmitters.
What does serotonin do and how is it affected during exercise?
Controls mood
Exercise: instantly boosts serotonin levels (anti-depressant)
What does dopamine do and how is it affected during exercise?
Responsible for motivation
Reward to motivate us
Experiments with dopamine receptors in rats
-> de-motivation/ starvation
Exercise: instantly boosts dopamine levels (motivators)
What does norepinephrine do and how is it affected during exercise?
Responsible for attention & perception, motivation; F&F
increased sharp decreased dull
Exercise: instantly boosts norepinephrine levels (attention)
How are neurons affected during learning?
Learning requires strengthening the relationship (affinity) between neurons through a dynamic mechanism called
long term potentiation (building strong synapses between the neurons makes it easier for signalling/ firing between them)
What are the learning pathways for neurons and how is this related to exercise?
Glutamate is sent from one neuron across the synapse to the dendrites of another.
If there are repeated firings, the genes inside the receiving neuron are turned on to produce building materials for the synapse to allow it to become permanently
But what has exercise to do with this? BDNF!
What is BDNF?
Brain-derived neurotrophic factor (a class of proteins)
Neurotrophins are chemicals that help to stimulate and control neurogenesis, build and maintain cell circuitry infrastructure
BDNF being one of the most active
The best way to think of them is as fertilizer for the brain
In the brain.
BDNF is active in the hippocampus, cortex, and forebrain—areas vital to learning, memory, and higher thinking. Hence, BDNF is important for long-term memory
Neuroplasticity
What is neuroplasticity?
The ability of the brain to shape itself according to experience, physical change on a neuronal level
How does BDNF work?
If you sprinkle BDNF on neurons in a petri-dish, the cells automatically sprouted new branches (synapses)
Like Miracle-Grow for the brain
1 - BDNF binds receptors at the synapse
2 - Activates genes that call for more BDNF, serotonin, and proteins that build synapse
3 - BDNF builds & strengthens the neuron protecting against cell death
What are the two types of activity?
AEROBIC:
- Requires presence of O2
- Primarily works type I muscle fibres
- Increases muscle endurance & capillary size
- Heart muscle to pump blood more efficiently
- Sustain for an extended period of time
- Heart rate between 120-150 BPM
- Increases heart rate and respiratory rate
ANAEROBIC:
- Does not require presence of O2
- Primarily works type II muscle fibres size/ strength
- You exercise until you gas out
- O2 builds up, lactic acid builds up; you feel the burn
- Can’t sustain this kind of activity for extended period
- 80 and 90% of your maximum heart rate (MHR)
Explain Russo-Neustadt et al. (2001)’ study
1 - Engaged in ‘voluntary running’
2 - Given anti-depressants
3 - Both
4 - Neither/ Control
They were then exposed to a stress swimming task.
Results:
BDNF levels in untreated animals (Group 4) were lowered
Animals in physical training or anti-depressants (Group 1 and 2) had BDNF restored to baseline
Animals with both (Group 3) showed increase in hippocampal BDNF well above baseline
→ Exercise has an anti-depressant effect/ stress-buffering effect
How do we measure physical activity?
Objectively
e.g. activity and heart rate monitors, accelerometry, step counters, fitness measures
Self-report:
Simple questions
PA recall (e.g. Blair’s seven day recall questionnaire)
PA diaries
What are the issues with self reporting physical activity?
Complex behaviour A whole class of behaviours theoretically includes all bodily movements FITT: frequency, intensity, time, type Recall bias Overestimation
What are the benefits of HIIT?
Improves oxidative capacity, cardio-metabolic health and insulin sensitivity
Encourages the liver to absorb more fat from blood before using it
Increases basal metabolic rate (BMR)
What are the psychological determinants of physical activity?
Self-efficacy
Social support
Motivation/intention
Beliefs
Barriers/benefits
What are the barriers of physical activity?
Lack of time
Feeling too tired
No money (!)
Not knowing where to start/ what to do…
Internal triggers (unhelpful thinking)
What did Romeo et al (2019) find?
A systematic review of 9 RCTs that used a smartphone app as the key intervention to increase PA (measured as either moderate-to-vigorous PA, minutes or steps)
Findings show that apps have a significant positive effect on physical activity when used over a short-term period (less than 3 months) and where apps target PA alone, rather than physical activity in combination with other health behaviours
What are the different
levels of exercise intervention?
Individual: allows tailoring, flexible scheduling, labour intensive
Group: added group dynamics, ‘buddying’, less tailoring, less labour intensive
Organisational/community (e.g. schools, corporate fitness/work, primary care): wide impact, existing infrastructures, lack of facilities and trained staff, often favours those who need it least
Societal (e.g. mass media campaigns, transport policy, environment, PE curriculum, insurance incentives): widest impact
