BIOL 430 3-5 Length-Tension Curve & Muscle Fiber Types

What is the relationship between sarcomere length and tension

-length of sarcomere has influence on force generated when sarcomere is shortened/contracted

-ideal length of sarcomere is about 80-120% of resting length; produces maximum tension

What are the three types of skeletal muscle fibers

-slow oxidative fibers (SO), fast oxidative fibers (FO), and fast glycolytic fibers (FG)

-whole muscles contain all three types w/ diff proportions

Describe slow oxidative fibers

-slow to contract

-aerobic respiration

-gluteus minimus is MAINLY SO fibers

Describe fast oxidative fibers

-fast to contract

-aerobic respiration

Describe fast glycolytic fibers

-fast to contract

-anaerobic respiration

-gluteus maximus is MAINLY FG fibers

Characteristics of skeletal muscle fibers

refer to image

What are the four influencing factors on muscle contraction force

1. Frequency of stimulation (tetanus/wave summation)

2. Number of muscle fibers stimulated(motor unit recruitment)

3. Size of muscle fibers (Diameter)

4. Degree of muscle stretch (80-120%)

Describe the behaviors of muscle performance

-physical training alters appearance of skeletal muscles

-muscles change in size, not # of muscle fibers

-other cellular components of muscle fibers also undergo change in response to muscle use

Differentiate hypertrophy and atrophy

-hypertrophy: structural proteins are added to muscle fibers; diameter increase (more myofibrils)

-atrophy; structural proteins are lost; muscle mass decreases

Describe the effects of aerobic/endurance exercise on the muscle

-little force on muscles over multiple repetitions; utilizes oxidative fibers (SO and FO fibers)

-leads to increased # of mitochondria, myoglobin synthesis (carries O2), muscle capillaries/angiogenesis (resists fatigue), conversion of FG to FO (less muscle mass)

Describe the effects of anaerobic/resistance exercise on muscle

-high force on muscles over short period; utilizes high # of fast glycolytic fibers (FG cells)

-leads to increased # of myofibrils (hypertrophy), CT (perimysium, epimysium, endomysium), force production, and conversion of FO to FG

Describe different PED/PES

-anabolic steriods: testosterone -> stimulates muscle formation -> increased mass

-erythropoietin (EPO): hormone (produced in kidney) producing RBC -> more O2 to muscles -> more aerobic respiration/less fatigue

-human growth hormone (hGH): promotes tissue/muscle recovery

-creatine: production of more ATP from the creatine phosphate system and allow more explosive power output

Describe side effects of PED/PES

-anabolic steriods: agression, cardiovascular disease

-erythropoietin (EPO): blood viscous, high BP

-human growth hormone (hGH): unpredictable side effects due to physiological strain

-creatine: NA

Describe what sarcopenia is

-irreversible muscle atrophy with age (starts around 30-40); why athletic performance decreases

-muscle fibers die and get replaced w/ non-contractile connective tissue (less crossbrdige formations)

-sarcopenia delayed w/ exercise