WEEK 16: SPORTS

body comp of males

higher muscle mass to weight ratio

lower fat %

greater strength

cardiovascular attribute of males

larger heart

higher blood volume and Hb concentration

higher maximal oxygen consumption

power and strength of males

men hv higher testosterone lvls = develop stronger muscles

endurance of females

greater reliance on fat metabolism during (endurance) exercise

strength definition

maximum force muscle/muscle group generates at once

what is strength determined by

contractile force of muscle cross-sectional area

neural adaptation

muscle fiber type (more fast twitch fibers)

what is neural adaptation

ability to recruit motor units

what is strength improved by

high load, low repetition resistance training

increases bone density, muscle hypertrophy, CT toughness

power definition

rate of work

strength + speed

e.g. sprint, jump, throw

power formula

force * velocity

what is power improved by

plyometrics - fast, explosive combo of muscle stretching and contracting to increase power

olympic lifting

endurance definition

ability of muscle to sustain repeated contraction or hold contraction for long

what is endurance determined by

oxidative capacity of muscle

mitochondria density

capillary supply

amt glycogen

what is endurance improved by

low load, high repetition resistance training

aerobics

list energy systems used by muscles

1. phosphocreatine-creatine

2. glycogen-lactic acid (anaerobic glycolysis)

3. aerobic

fuel source: ATP

existing atp stores

fuel source: PCr

phosphocreatine

fuel source: glycogen-lactic acid

muscle glycogen broken down to glucose

fuel source: aerobic system

carbs, fats, protein

duration/intensity: ATP

0-3 secs

maximal

half of 50 meter das

duration/intensity: PCr

3-15 secs

maximal

duration/intensity: glycogen-lactic acid

15 secs - 2 mins

high

duration/intensity: aerobic 

2 minutes 

submaximal

key feature: ATP

immediate energy

small stores

key feature: PCr

rapid ATP regeneration without oxygen (muscle cells more PCr than ATP)

energy transfer from PCr to ATP within fraction of second

key feature: glycogen-lactic acid

1. ATP produced quickly without O2 + lactic acid (diffuses from muscle cell to ISF and blood)

2. 2.5x faster than oxidative mechanism of mitochondria but ½ slower than phosphagen sys

key feature: aerobic

sustained ATP production

requires o2

produces co2 and h2o

muscle hypertrophy

increase in muscle fiber size due to resistance training

metabolic adaptation of aerobic training

increases

mitochondria density

oxidative enzymes

capillary supply = improves endurance

metabolic adaptation of anaerobic training

increases glycogen store and glycolytic enzyme power

neural adaptation of muscles

improved motor recruitment, firing rate, synchronization

strength with reduced hypertrophy

respiration during exercise

1. ventilation, CO2, H+ increases

2. ventilation increases disproportionately from psychological stimuli and muscle reflexes

3. o2 diffusion capacity increases from increased bloodflow in pulmonary capillaries

cardiac output during exercise

increases to ~5 L/min at rest to 20-25 L/min due to increased HR and SV

SV definition

volume of blood pumped per beat

bloodflow distribution during exercise

bloodflow diverted from digestive system to active sk muscles

increased skin bloodflow, radiating heat to environment

BP during exercise

systolic BP increases

diastolic BP remains stable/decreases slightly

what happens to body heat during exercise

muscular activity inefficient = energy released as heat

thermoregulation (sweating = coolant, increased bloodflow in skin)

what happens to body fluids during exercise

1. dehydration (sweat loss = decreased blood volume, increased HR, impaired thermoreg)

2. electrolyte loss (losing Na+ and K+ can lead to cramps/hyponatremia)

drugs affecting atheletes

1. stimulants (amphetamine, caffine)

2. anabolic steroids

3. erythropoietin

how do stimulants affect athletes

increases alertness and masks fatigue but raises HR

how do anabolic steroids affect athletes

increases muscle mass and strength but long term side effects (liver damage, cardiovascular disease, hormonal imbalance)

how do erythropoietin affect athletes

increases rbc production but increases risk of thrombosis

what does exercise reduce the risk of

1. cardiovascular disease

2. type 2 diabetes

3. obesity

4. osteoporosis

5. certain types of cancer e.g. colon, breast

6. depression, cognitive decline

how does exercise affect endocrine system

increases insulin sensitivity

components of muscle performance

strength, power, endurance

how does hot/humid climate affect exercise

increases core temp and risk of heat illness

greater strain on cardiovascular system for heat reg

how does high altitude areas affect exercise

lower pO2 causes hypoxia (lower o2 supply for homeostasis)

body adapts by increasing rbc and ventilation

oxygen debt

epoc (excess post exercise oxygen consumption)

o2 consumption remains high after exercise to restore stored oxygen (o2 in body without having to ventilate):

1. replenish ATP and PCr stores

2. converts lactic acid back to glucose in liver

3. re-saturate myoglobin with o2

4. increase metabolism

effect of testosterone

anabolic effect

deposition of protein to muscles

what is power determined by

1. strength of muscle contraction

2. distance of contraction

3. number of contractions per min

phosphagen system composition and duration

ATP + phosphocreatine

8-10 secs combined

maximal (short bursts of power)

why is cardiac output important

determines o2 delivery rate to muscles

molecule commonly lost in sweat

Na+

which system has fastest ATP rate

phosphagen

which fiber type has highest mitochondria density

type I 

types of muscle fibers

I - slow

II - fast (A, X, C)

type of metabolism of type I fiber

oxidative aerobic

type of metabolism of type IIa fiber

mixed, oxidative and glycolytic (anaerobic & aerobic)

think: IIA (AND!)

type of metabolism of type IIx fiber

anaerobic (glycolytic)

which energy systems does aerobic system replenish energy for?

• ATP

• phosphocreatine

• glycogen-lactic acid

which energy systems does glycogen-lactic acid system replenish energy for?

• PCr

• ATP

which energy systems does PCr system replenish energy for?

ATP

how is lactic acid removed

1. converted to pyruvic acid, metabolized oxidatively by tissues

2. converted to glucose in liver

changes in hypertrophied muscle

increased:

1. amt myofibril

1. mitochondrial enzymes

2. components of phosphagen system

3. fats

4. oxidation rate

fast vs. slow twitch muscle fibre

fast:

• 2x larger diameter

• enzymes (for energy release in phosphagen and glycolactic acid systems) faster

slow:

• endurance

• more mitochondria

• more myoglobin

• enzymes of aerobic system more active

• more capillaries