Slide 1The Endocrine SystemTestosteroneGrowth HormoneInsulin-Like Growth Factor ICortisolCH. 4: BIOMECHANICS OF RESISTANCE TRAININGMusculoskeletal System: JointsMusculoskeletal System: MusclesLeversLEVERSAnatomical PlanesBiomechanical Factors in StrengthFree Weight & MachinesBiomechanical ConcernsSpecificityCH. 3: ENDOCRINE RESPONSE TO RESISTANCE EXERCISEThe Endocrine System•Can be manipulated naturally with resistance training to enhance development of various target tissues leading to improvement in performance (General Adaptation Syndrome)•Hormone responses are tightly linked to the characteristics of the resistance training protocol•Two classes of hormones tightly linked to strength training•Anabolic Hormones- Testosterone, Growth Hormone, and Insulin-like Growth Factor•Adrenal Hormones- CortisolTestosterone•Male sex hormone (also present in women, but at much lower levels)•Has direct and indirect effects on muscle tissue•Promotes growth hormone (indirect)•Increases # of neurotransmitters on a cell (indirect)•Influence structural protein changes (direct)•Increases muscle size by binding to DNA and increasing DNA transcription  induces protein synthesis•Binds to cell receptors causing increase in calcium release•Serum Testosterone levels can be increased with various exercise prescriptions•Large muscle group exercises (clean, squat, deadlift)•Heavy resistance (85-95%)•Moderate to high volume (multiple sets/exercises)•Short rest intervals (30-60sec)•Years of training (2yrs +)Growth Hormone•Secreted by the pituitary gland, GH also referred to somatotropin•Enhances AA uptake and protein synthesis leading to hypertrophy•Several other benefits include glycogen sparing, collagen and cartilage growth, improved kidney function, immune cell function•Studies have shown that although hypertrophy make occur, GH treatment in normal individuals may not increase strength. Benefits are outweighed by a variety of secondary effects.•GH levels can be enhanced naturally through resistance training, but it is unclear as to what protocols yield the largest increaseInsulin-Like Growth Factor I•Secreted from the liver in response stimulation from GH•Little research has been done concerning IGF-I, but it is closely linked to GH and is also potentially stored in muscle and released during training… basically it’s there doing something… we have yet to figure out what and why.Cortisol•Adrenal hormone secreted from the adrenal cortex•Primary signal hormone for CHO metabolism•CATABOLIC  inhibits protein synthesis•Cortisol levels increase with high volume, low rest resistance training•Plays a role in suppressing immune cells  impacts recovery long-term*KEY POINT: Acute increases in Cortisol levels are GOOD. Chronic increases in Cortisol levels are BAD and indicate overtraining.CH. 4: BIOMECHANICS OF RESISTANCE TRAININGMusculoskeletal System: Joints•Fibrous Joints- no movement•Sutures of the skull•Cartilaginous Joints- limited movement•Intervertebral disks•Synovial Joints- considerable movement•Uniaxial Joints (Hinge)- Ex: Elbow, Knee•Biaxial Joints- Ex: Wrist, Ankle•Multiaxial Joints (Ball and Socket)- Ex: Shoulder, HipMusculoskeletal System: Muscles•Agonist- prime mover, muscle directly involved in causing movement•Ex: Bench Press: Agonist is the pec•Antagonist- muscle capable of slowing down or stopping the movement, provides joint stabilization, typically “opposite” the agonist•Ex: Bench Press: Antagonist is the lat •Synergist- assists indirectly with movement, help control body movement when agonist crosses to joints•Ex: Squat: Synergerists are the glutes (hip extensors counteract the firing of the quads which are hip flexors and knee extensors)Levers•Fulcrum- pivot point of a lever•Moment Arm- perpendicular distance from the line of action of the force to the fulcrum•Muscle Force- force generated by the muscle•Resistive Force- force generated outside the body•First Class Lever- muscle force and restive force are on OPPOSITE sides of the fulcrum•Ex: Elbow extension against resistance•Second Class Lever- muscle force and resistive force are on the SAME SIDE of the fulcrum, the resistive force is CLOSER to the fulcrum•Ex: Plantar Flexion (standing calf raise)•Third Class Lever- muscle force and resistive force are on the SAME SIDE of the fulcrum, the muscle force is CLOSER to the fulcrum•Ex: Biceps CurlKEY POINT: A person with tendons inserted farther along the bone are at a mechanical advantage because of a longer moment arm. However, the individual experiences a loss of speed because the same amount of muscle contraction results in less movement of the jointLEVERSAnatomical Planes• Sagittal Plane- divides the body into right and left•Frontal Plane- divides the body into front and back•Transverse Plane- divides the body into upper and lowerBiomechanical Factors in Strength• Neural Control• Recruitment- Number of muscle fibers activated• Rate Coding- speed at which motor units are fired• Muscle Cross-Sectional Area- thicker muscle is able to exert greater force• Arrangement of Muscle Fibers- more sarcomeres in parallel arrangement leads to greater contractile ability• Muscle Length- muscle has the greatest potential for contraction at resting length• Joint Angle- joint angle effects mechanical advantage Ex: Biceps Curl• Body Size- as body size increases body mass increases faster than muscle strengthFree Weight & MachinesFree Weights• Whole Body Training• More Similar to Athletic MovementsMachines• Safer• Varying Moment Arm• Design Flexibility• Flexibility with Injured AthletesBiomechanical Concerns• Spine Safety• A “flat back” is critical to preventing back injuries• Shoulders back, chest out, hips rotated back• Using the Valsalva Maneuver supports the spine and minimizes force required for the erector spinae muscles to support the spine• Weight Belts•Knee Safety• Torque through the knee joint can cause Tendonitis• Developing musculature around the knee can minimize force through tendons, also prevent acute knee injuries•Shoulder Safety• Highly Mobile  more prone to both chronic and acute injuries• Balanced training• Preventative/Corrective ExercisesSpecificityIS IT BENEFICIAL TO MIMIC SPECIFIC ATHLETIC MOVEMENTS IN THE WEIGHT ROOM WITH WEIGHT????IF SO, HOW DO WE DO IT SAFELY????IF NOT, WHY??? AND HOW, THEN,