Types of Muscles Smooth w Involuntary muscle; controlled unconsciously w In the walls of blood vessels and internal organs Cardiac w Controls itself with help from nervous and endocrine systems w Only in the heart Skeletal w Voluntary muscle; controlled consciously w Over 600 throughout the body

SKELETAL MUSCLE STRUCTURE

KEY POINTS w An individual muscle cell is called a muscle fiber. w A muscle fiber is enclosed by a plasma membrane called the sarcolemma. w The cytoplasm of a muscle fiber is called a sarcoplasm. w Within the sarcoplasm, the T tubules allow transport of substances throughout the muscle fiber and the sarcoplasmic reticulum stores calcium.

AN ACTIN FILAMENT

The Myofibril w Myofibrils are made up of sarcomeres, the smallest functional units of a muscle. w A sarcomere is composed of filaments of two proteins, myosin and actin, which are responsible for muscle contraction. w Myosin is a thick filament with a globular head at one end. w An actin filament—composed of actin, tropomyosin, and troponin—is attached to a Z disk.

Events Leading to Muscle Fiber Action A motor neuron releases acetylcholine (ACh). 2. ACh binds to receptors on the sarcolemma. 3. The action potential triggers release of Ca2+. 4. The Ca2+ binds to troponin on the actin filament, and the troponin pulls tropomyosin off the active sites, allowing myosin heads to attach to the actin filament.

Resting Membrane Potential (RMP -Difference between the electrical charges inside and outside a cell, caused by separation of charges across a membrane -High concentration of K+ inside the neuron and Na+ outside the neuron w K+ ions can move freely, even outside the cell to help maintain imbalance w Sodium-potassium pump actively transports K+ and Na+ ions to maintain imbalance w The constant imbalance keeps the RMP at –70mV Action potentials—rapid, substantial depolarization of the membrane (–70 mV to +30 mV to –70 mV all in 1 ms)

RESTING STATE

GOLGI TENDON ORGAN

Slow-Twitch (ST) Muscle Fibers High aerobic (oxidative) capacity and fatigue resistance Slow contractile speed (110 ms) and myosin ATPase 10–180 fibers per motor neuron Low sarcoplasmic reticulum development

Fast-Twitch (FTb) Muscle Fibers Fast contractile speed (50 ms) and myosin ATPase 300–800 fibers per motor neuron High sarcoplasmic reticulum development The difference in force development between FT and ST motor units is due to the number of muscle fibers per motor unit, not the force generated by each fiber.

Fast-Twitch (FTa) Muscle Fibers Intermediate Muscle Fibers – Specificity of Training is the key. Will mimic other fibers

A history of Anabolic Steroids 1889 Mr. Se’quard 1920’s Dr. Koch 1960’s Dr. Ziegler 1970’s Olympic Committee 1980’s NCAA Urine testing

Side Effects of Anabolic Steroids Cycling Stacking Androgenic, Anabolic Side Effects of Anabolic Steroids Gynecomastia Acromegaly Liver Disease Hirsutism Testicular Atrophy Acne Roid Rage

Supplements Creatine Androstenedione Ergogenic Aids

Functional Classification of Muscles Agonists—prime movers; responsible for the movement Antagonists—oppose the agonists to prevent overstretching of them Synergists—assist the agonists and sometimes fine-tune the direction of movement

Key Points Resistance training programs can produce a 25% to 100% improvement in strength within 3 to 6 months. Transient Hypertrophy—pumping up of muscle during a single exercise bout due to fluid accumulation from the blood plasma into the interstitial spaces of the muscle. Chronic Hypertrophy—increase of muscle size after long-term resistance training due to changes in muscle fiber number (fiber hyperplasia) or muscle fiber size (fiber hypertrophy). Muscle protein synthesis increases during the post exercise period.

Delayed-Onset Muscle Soreness (DOMS) Results primarily from eccentric action Is associated with damage or injury within muscle w May be caused by inflammatory reaction inside damaged muscles w May be due to edema (accumulation of fluid) I inside muscle compartment w Is felt 12 to 48 hours after a strenuous bout of exercise (Glycogen Synthesis Impaired)

Linear – Same exercises day in and day out Strength—few reps and high resistance (6-RM) Muscular endurance—many reps and low resistance (20-RM) Power—several sets of few reps and moderate resistance; emphasize speed of movement Muscle size—more than 3 sets of 6-RM to 12-RM loads; short rest periods Linear – Same exercises day in and day out Non-Linear – Changing the exercise routine on a daily basis

Study Questions When will your body synthesize proteins? Chronic Hypertrophy vs. Transient Difference in strength and endurance program Efferent and Afferent Sensory organs (muscle spindles and Golgi) All terminology associated with a nerve cell(dendrites, cell body, hillock, axon, nodes, Myelin sheath

Study Questions Know the resting voltage within a nerve and when it fires Chemicals released at the terminal end of nerve Sarcomere-Motor Unit-Calcium-Magnesium-Fine motor vs. Gross motor, Bands and Zones (Pg 320) Isometric, Isotonic, Isokinetic Eccentric, Concentric

Study Questions Initial strength gains (Engrams) Muscle Fiber types (I, IIa, IIb) Look at the True/False and Multiple Choice questions from chapter 12 & 15 Page 298 Interval Training, Circuit Training, Plyometrics