ExPhys Exam 5

Muscle fiber recruitment increases as

exercise intensities increase

Muscle fibers in order

Type 1 → type 2a → type 2x

up to 40% of VO2 max is usually what type of fibers?

Type 1

40-75% of VO2 max is usually what type of fibers?

Type 2a

>75% of VO2 max is usually what type of fibers

2x

and results in increased lactate and H+ production

Factors affecting fatigue in Ultra Short Term Performances (<10sec)

IIx fibers, motivation and arousal, PC and glycolysis, skill and technique, practice

Factors affecting fatigue in 10-60sec events (100m dash)

fast fibers, mainly glycolysis and PC, H+

Factors affecting fatigue in 60-180sec events (800m run)

mixed fast and slow fibers, 60/40 Aerobic/Anaerobic,

Factors affecting fatigue in events 3-20min (aerobic)

VO2 max, cardiac output, genetics and training, type 1 fibers, mitochondria/capillary density, training

Factors affecting fatigue in events 21-60 min(aerobic)

steady state VO2, running economy, lactate threshold, %type 1 fibers, biomechanics, bioenergetics

Factors affecting fatigue in events 1-4 hours (aerobic)

diet/supplements, steady state VO2, lactate threshold, type 1 fibers, biomechanics, bioenergetics, running economy,

elite marathoners possess

4L/min steady state VO2 (67)

VO2 peak ~85, influenced by running economy

genetics and intense training

Training principles

training programs should match the anaerobic and aerobic demands of the sport

Overload

Specificity

Reversibility

Components of a training session

warm up, workout, cooldown

Warm up

increase Q, muscle blood flow, muscle temp, enzyme activity

may reduce risk of exercise induced muscle injury

Workout

training session

Cool down

return blood pooled in muscles to central circulation

Training to improve aerobic power

interval training

long slow distance

high intensity continuous exercise

Training to improve aerobic power is designed to improve

VO2max, lactate threshold, running economy

Duration of interval

number of seconds

intensity of work interval

typically 85-100% HR

Duration of rest interval

ratio (work:rest)

1:1 means 75 sec work 75 sec rest

Number of interval sets

ex. 1 set

Number of work repetitions

ex. 8× 400m

Low intensity exercise

50-65% VO2 max or 60-70% HRmax

duration greater than event or competition

High intensity exercise

80-100% VO2 max for most athletes

at or slightly above lactate threshold

peak running velocity

highest speed that can be maintained for 5+ seconds, 60 seconds, etc.

Peak running velocity is inversely correlated to endurance race finish times

running velocity in training accounts for approximately 40-80% of race performance improvements

altitude training may not always

increase performance at sea level

(lower training intensity at altitude may result in de-training)

Live high, train low

Spend sleeping and resting time at altitude

increase rbc volume and oxygen transport capacity of blood

train at lower altitude (better performance gains vs living and training at sea level)

Most injuries are a result of

overtraining

The 10 percent rule for increasing training load

increase intensity or duration < or equal to 10 percent per week

Training to improve anaerobic power:

ATP-PC system, Glycolytic system

ATP-PC system

short (5-10sec) high intensity work intervals

30-60 sec rest intervals (little lactic acid is produced, so recovery is rapid)

Glycolytic System

short (20-60sec) high intensity work intervals

may deplete muscle glycogen levels (may alternate hard and light training days)

mega doses of antioxidants

thought behind it: exercise promotes formation of free radicals, may damage cells and contribute to fatigue

antioxidants may prevent damage and fatigue

however, high doses may block training adaptations (free radicals activate signaling pathways involved in muscle adaptation to training)

DOMS

delayed onset muscle soreness

appears 24-48 hours after strenuous exercise

due to microscopic tears in muscle fibers or connective tissue

eccentric causes more damage than concentric

slowly begin a specific exercise over 5-10 training sessions to avoid

common treatment for DOMS

rest, ice, compress, elevate

NSAIDS (ibuprofen, aspirin)

Steps leading to DOMS

structural damage to muscle fiberes

membrane damage

Ca2+ leaks out of SR

breakdown of cellular proteins

inflammatory response

edema and pain

Repeated bout effect

repeated bouts of exercise will lead to adaptation and less muscle damage

could be neural, connective tissues, or cells

Training to improve flexibility

stretching exercises do improve flexibility (limited evidence that flexibility reduces injury risk)

Static Stretching

hold stretch position for 10-60 sec (repeat 3-5 times)

preferred technique

less chance of injury/soreness

less muscle spindle activity

Symptoms of overtraining

decrease in performance, loss of body weight, chronic fatigue, increased number of infections, elevated HR and blood lactate levels during/after exercise, psychological staleness

Determinants of Health and longevity

Genetics - 30

Lifestyle behavior - 40

environmental factors - 20

health care - 10

Epidemiology

study of patterns and determinants of health and disease

Exercise epidemiology

branch that investigates the role of SB and PA in determining health and disease

Sedentary Behavior (SB)

any waking behavior with energy expenditure of less than or equal to 1.5 MET’s

Physical Activity (PA)

any bodily movement produced by muscular contractions

MET-hr/week

measure of your total energy expenditure during PA

Physical fitness

characteristics which people possess that relates to their ability to perform physical activity

Exercise

planned PA with a goal of improving physical fitness; is a subset of PA

Physical Inactivity (PI)

an individual is labeled as this when they do not meet the recommended PA guidelines

Hazard Ratio

an estimate of the risk of death in a group of individuals compared to a reference group

Light PA

1.5-3 MET

Moderate Physical Activity

3-6 MET

Vigorous PA

>6 MET

Daily sitting time

increases all-cause mortality

PA decreases risk of all cause mortality

meeting rec decreases by 30 percent

3x rec decreases by 40 percent

10x rec also 40 percent

Risk factors for coronary heart disease

Age, male, hereditary, diabetes, smoking, high BP, blood cholesterol, obesity, PI

Normal BP

120-129/80

Stage one Hypertension

130-139/80-89

Stage 2 hypertension

>140/>90

aerobic activity/exercise lowers arterial BP by

vasodilation, angiogenesis, reduced arterial stiffness

PA reduces risk factors for stroke by decreasing

PI, dyslipidemia, hypertension, diabetes, obesity

PA/exercise effects on the brain that reduce the risk of Alzheimers

Decreased oxidative damage, improved brain blood flow, increased neurogenesis, increased hippocampus, decreased inflammation

Aerobic PA/exercise reduces risk of Type 2 diabetes

By improving glucose homeostasis (increase mito biogenesis, increased GLUT4 abundance and insulin sensitivity, increased capillarization)

Resistance training reduces risk of cancer by

reducing inflammation and improving immune function

Overload

doing more than accustomed to doing

specificity

improvements based on what you’re doing and muscles you’re using

reversibility

lose it quicker than you gain it

overtraining

too much overload and/or too little recovery

training response

overload decreases fitness, then recovery leads to positive adaptation

80-20 rule

80% should be below LT, 20% of training should be at or above lactate threshold

resting lactate is around

1 (not zero)

graphs shift ____ as fitness increases (more mitochondria)

right

NEAT

non-exercise activity thermogenesis

(low MET value but not sedentary)

artherosclerotic blockade

plaque in arteries