Evolved To Move? Flashcards
Why is evolution important to sport and exercise?
Evolutionary perspective is necessary to explain why we move as we do. (Exercise subdisciplines explain how we move)
How have humans evolved to move?
Relative to other animals, humans aren’t particularly good at strength, speed etc. But Homosapiens are all rounded, well accomplished - good at using tools effectively to support our behaviour/survival
How much and what kinds of physical activity are humans built to perform?
Many different activities (eg. running, climbing, crouching, playing) but there’s no universal exercise prescription
To what extent are humans also adapted to be physically inactive?
Trade-off energy utilisation between PA and reproduction - periods of activity and inactivity (ie. staying alive & propagating our genes)
Why do most humans avoid physical activity when its so vital to health?
Perceived by some as unpleasant or wasteful use of resources. Society generally marginalises PA
What are common forms of movement?
- Locomotion
- Climbing
- Throwing
- Jumping
- Swimming
What type of symmetry allows organisms to move purposefully and efficiently?
Bilateral Symmetry
Why is bipedalism favoured by natural selection?
Walking on two feet enabled hominins to travel further in more open habitats that were becoming more common in Africa.
Bipedalism frees up our hands, to be able to carry tools, fight etc.
Favoured features of homo erectus?
- Larger brain
- Long legs
- Short arms
- Arched feet
Adaptations of the human foot?
- Large heel
- Ankle adapted for walking
- Stiff mid foot for propulsion
- Adducted big toe in line with other digits
What are human body adaptations that favour endurance activities like running?
- Arched feet, heel bone and springy archilles tendon
- Large hip, knee and ankle joints. Strong hip and knee muscles
- Multiple sensitive balance organs. Tall narrow body
- Hairless, sweating and other thermoregulatory mechanisms
What type of muscle fibres do human limb muscles need to be more biased toward?
Slow twitch type I muscle fibres
What is the purpose of describing anthropometric characteristics?
- Assess growth and development in children and adolescents
- Estimate body composition
- Assess effects of interventions
What are 6 common anthropometric measurements?
- Height
- Weight
- Body mass index
- Body circumferences
- Body width measurements
- Body composition
What is BMI?
- Does not measure body composition
- Its ok for descriptive purposes and esp. useful at population levels but not suitable at individual level
- Does correlate with disease prevalence and mortality rates
- Use along with more objective measure
What is anthropometry?
Standardised techniques to quantify or predict body size, proportion and shape
What is bone density?
Body mass per unit body volume
What is specific gravity?
Body mass in air, divided by loss of weight in water.
BM / (BM-BW)
What is body mass?
Fat mass + fat free mass + other lipids (esp. cell membranes)
What is fat patterning?
Distribution of fat mass
What is the only direct way to measure body composition?
Cadavers
What are the indirect ways to measure body composition?
- Multi-tissue imaging (DXA)
- Labelled water dilution
- Densitometry
What are the doubly indirect ways to measure body composition?
- Bioimpedance analysis (BIA)
- Skin fold thicknesses
- Surface scanning
- Single tissue imaging
Why is it important to know hydration state?
Water comprises majority of mass within most cells, and esp. around them
What are the pros and cons of multi-tissue imaging?
PROS:
- Can measure FFM and bone density, regionally and whole body
- High accuracy (typical error ~1-2% for FM)
CONS:
- Specialised and expensive
- Technical problems, eg. athletes’ size, recent meal, muscle energy
What are the 5 steps of labeled water dilution?
- Dilute known mass of labeled water into body
- Measure its concentration once equilibrated with body water
- Calculate TBW, after subtracting baseline concentration of that labelled water
- Divide TBW by 0.732 to get FFM
- BM - FFM = FM
What are the pros and cons of labelled water dilution?
PROS:
- Accurate: typical error ~2%
CONS:
- Time consuming, specialist, expensive
- Must be euhydrated
- TBW not always 73% FFM
- Don’t know distributions of FFM or FM
What is densitometry (underwater weighing)?
- FFM is denser than FM
- Knowing body density, and the estimated densities of FM and FFM, we can calculate the proportion of those in the body
- Body Density = mass/volume
What are the pros and cons of densitometry (air displacement)?
PROS:
- Convenient, quick, less uncomfortable (claustrophobia)
- So is replacing underwater weighing
CONS:
- Price
- Technical limitations eg. hair, clothing, temp
- Over estimates FM by less validation for children
What are issues with densitometry?
- Doesn’t give any info on distributions of FFM or FM
- Main sources of error: Variable densities of body tissues, Lungs residual volume or failure to exhale to that volume, trapped air in clothing, hair and GI tract
What are the pros and cons of bioimpedance analysis?
PROS:
- Quick, convenient, medium accuracy (esp. if same device over time within person)
- Different frequencies; may differentiate intra and extra cellular water
- Multi-electrodes; may differentiate all limbs and trunks
CONS:
- Accuracy ~4-5% but poorer with high FM
- Need standardised conditions: dehydration, too warm, menstrual cycle
What are the pros and cons of skinfold thickness?
PROS:
- Quick, convenient, medium accuracy (esp. if same experienced tester over time)
CONS:
- Typical error ~4% in best conditions
- Technique important; callipers, location, compression duration etc.
- Sensitivity of clients
- Not used with high BF %
What are the 5 limitations with skinfolds?
- Constant compressibility (within and between people)
- Skin thickness negligible or constant fraction of skinfold
- Fixed adipose tissue patterning
- Constant fat fraction in adipose tissue
- Fixed proportion of internal (visceral) to external (subcutaneous) fat
What are some newer technologies in anthropometry?
- Ultrasound
- 3D scanning of body surface
- 2D images (photos)
Why is skeletal muscle mass important?
- For physical capabilities (strength & power)
- Largest tissue mass in body
- Produces heat
- Is the major determinant of daily energy use
- Insulator
- Major endocrine organ
Why is fat mass important?
- Valuable fuel/energy source
- Mass to be carried
- Insulator
- Not merely a passive tissue
- So adverse metabolic and sex hormone effects of both excess and insufficient fat mass
Why is fat a valuable source of energy?
- It’s twice as energy dense as CHO and protein
- Fat cells provide muscle cells with energy during exercise (as free fatty acids)
- Can be dominant fuel source in exercise
How can you maximise fat during exercise?
- Not too intense
- Prolonged exercise
- Don’t eat CHO before or during exercise
- More aerobically trained
What is the most efficient way to store energy?
Store it as fat
What are the problems of insufficient fat?
Relative Energy Deficit Disorder (RED-s):
- Osteoporosis
- Amenorrhoea
- Affects males too
What are the problems of excess fat?
- If too much is gained, its harder to lose
- Initial fat gains partly hypertrophy (larger cells) then mostly hyperplasia (more cells)
- Fat mass is regulated at higher ‘set point’/’settling point’
What are myokines?
- Muscle factors
- Anti-inflammatory
- Help mobilise fat from adipocytes and turn adipose tissue into an energy-using tissue
What are adipokines?
- Adipocyte factors
- Pro-inflammatory
- Some adipokines have metabolic roles eg. to regulate itself
What are the 2 paradoxes of fat within muscle?
- Intra-muscular triglycerides levels increase in athletes and in obesity and diabetes
- Sarcopenic obesity
What is sarcopenia?
- Age-related, active loss of muscle mass and strength
- Impairs movement and many muscle processes
What are practical suggestions for maintaining body composition?
- Ideally deemphasise weight loss as a focus of exercise
- Nutrition and exercise both important
- Varied exercise
- Adequate sleep and avoid prolonged stress
What is the evolution of our human musculoskeletal system? (6)
- Mass concentrated in core
- Proximal muscles tend to be wider, heavier and stronger (as you get further away your muscles get much more slender)
- Good distance runners
- Powerful throwers
- Heel was important development
- Legs proportionally longer and arms shorter than ancestors
How does the turning effect work?
- Torque (t) is the turning effect
- Product of magnitude of force (f) and distance from the axis (r)
- T=Fr
What is a class 1 lever?
- Axis is the middle of the resistance and the effort
- Usually a balancing lever
- eg. see-saw
- In the body: atlanto-occipital joint
What is a class 2 lever?
- Resistance and effort applied on one side of the axis
- Effort further from axis than resistance
- eg. wheelbarrow, nut-cracker
- In the body: metatarsophalangeal joint
What is a class 3 lever?
- Resistance and effort on one side of the axis
- Resistance further from axis than effort
- eg. crane, diving board
- In the body: Most long bones
Why can you calf raise so much weight?
- Class 2 lever at ball of foot - mechanical advantage for muscle
- Gastrocnemius and Soleus can achieve high force values
- Muscle configuration is evolved
- High force capacity is evolved and enhanced across the lifespan by weight-bearing exercise
What is the effect of using chains?
- Resistance increases with bar height
- Increase in resistance roughly balances with increase in joint torques as bar height increases
- End of lift should feel as difficult as beginning
- Bands have a similar effect
What joints have mechanical disadvantage?
- Nearly all joints involving long bones
- Because they require much greater muscle force than resistive force to move or maintain equilibrium
Why did evolution favour the mechanical disadvantage of long bones?
- Tendon attachment close to joint increases range of motion
- Allows end of limb to reach high speeds
- Because muscles are limited in how much they can shorten
What happens to ROM when torque is increased?
Increase torque = loss of ROM
What are the 5 aspects of Health at Every Size (HAES)?
- Enhancing health: without focusing on weight loss or achieving a specific ideal weight
- Size and self acceptance
- The pleasure of eating well
- The joy of movement
- An end to weight bias
When was the BMI values changed and what was it changed too?
In 1998, the normal/overweight cut off was changed from BMI 27.8 to BMI 25
What is the relationship between obesity and ill health?
- The evidence between obesity and ill health isn’t very strong whereas the evidence between weight loss and ill health is very strong
- Some studies have indicated that those in the ‘overweight’ category live longer than those in the ‘normal’ weight
What is the NZ definition of health?
In health and physical education, the focus is on the well-being of the students themselves, of other people, and of society through learning in health-related and movement contexts
What does the WHO state about health?
That health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity
Do diets work?
Most people regain lost weight in the long term, with only between 5-18% maintaining weight loss. 1/3 of people actually gain more weight
Can you be fat and healthy?
- Being unfit is a problem for all body types
- If you are overweight or obese and fit, the health outcomes are very similar to being lean and fit
What percent of US women report disordered eating behaviours?
75%
What is curvy yoga?
Yoga as a form of movement pleasure and acceptance of you and your bodies capabilities right now. Strictly not weight loss focused
