KIN 3306 1nd EditionExam # 2 Study Guide Lectures: 5 - 7Lecture 5 (March 3)The Structure of a Muscle Fiber/Muscle Cell:The Components of a Muscle Fiber:- The plasmalemma attaches to tendons, folds for stretching, has junctional folds, and transports in and out of the cell.- The sarcoplasm is a gelatin-like substance that is the storage site for glycogen, myoglobin, and other proteins/minerals/fats/organelles.- The transverse tubules run laterally through the muscle fiber and are the path for nerve impulses.- The sarcoplasmic reticulum runs parallel to the muscle fiber and is where calcium is stored.The Components of a Myofibril:We can break down myofibrils into sarcomeres. The sarcomere is what is physically contracting to allow our muscles to contract.The Components of a Sarcomere:- The sarcomere is the basic contractile unit of a myofibril and consists of the I-band, A-band, H-zone, M-line, and Z-disc and includes two types of protein filaments myosin (thick) and actin (thin).- Myosin compromises 2/3 of skeletal muscle protein and has globular heads that form cross bridges. The titin filaments stabilize myosin by putting everything back into startingposition after contraction.- Actin has Tropomyosin that wraps around actin and Troponin that is bound at intervals to actin and Actin is anchored to the Z-disks. The purpose of Tropomyosin is to block myosin binding sites on actin. When calcium is bound to troponin, it will then move Tropomyosin.Muscle Contraction begins with a neural impulse. Muscles are also voluntary. Our muscles are divided into motor units and one motor neuron innervates several muscle fibers. The phases of muscle contraction are listed below. What happens is that AP leads to calcium release, then troponin moves tropomyosin so actin and myosin can bind, the power stroke occurs which is themovement of myosin to contract the sarcomere, and then ATP is used to fuel muscle contraction.- Action potential/calcium release- Calcium-troponin binding, tropomyosin shift- Actin-myosin binding- Myosin power stroke/ATP bindingThe Resting Membrane Potential is -70 mV. It is caused by an uneven separation of charged ions inside and outside of the cell. There are less ions inside the cell versus outside of the cell. To maintain the negative charge of -70 mV, we have a Na/K pump. An AP is a disruption of this resting charge that propagates an electrical impulse into the cell.Action PotentialThe initial stimulus comes from neurotransmitters such as Ach. This stimulus initiates the AP. Repolarization is when K runs out. In the dip after #7, this stage is called Hyperpolarization where the K gates are not tightly regulated so they stay open a little bit longer than they need tobe opened so K will leak a bit more. AP is always the same magnitude. What can make AP strongor less strong is summation and recruitment.Neuromuscular JunctionThe neuron and the muscle do not actually touch. The neuron sits in a fold within the plasmalemma and as AP goes down into the junction, there is a neurotransmitter that carriesthe signal from the neuron to the muscle fiber. As it gets to the end, the neurotransmitter is released into the space, synaptic cleft, the Ach binds to the plasmalemma, and this is the initial signal that starts the AP so it can get over the -55 threshold. It goes from electrical signal  chemical signal  then reinitiates the electrical signal that then goes into the muscle fiber.Energy for Contraction The ATP binding sites are on the myosin head. ATPase, on the myosin head, splits into ADP and Pi. The energy released fuels the tilting of the myosin head, which is the power stroke. Additional ATP is required to keep the contraction going. ATP allows myosin to reach forward and grab actin. Myosin can either be bound to actin or ATP but not to both.Muscle RelaxationThe calcium pumps return calcium to the SR where it is stored for future use. Calcium availability is important because the lack of calcium will result in fatigue where you cannot contract anymore.Muscle Fiber Type Characteristics- Type 1 Fibers are slow twitch/slow oxidative and are associated with the color white. o Distance runners, triathletes, cyclists- Type2 Fibers are fast twitch.o Sprinters, weight lifters, hockey playersFactors that Influence Muscle Force- Number of motor units activated- Type of motor units activated- Muscle size- Initial muscle length- Joint angle- Speed of muscle actionMuscle Fatigue during Exercise - If short term, fatigue is going to come from acidity. The acid denatures proteins and stops proteins from functioning.- If long term, fatigue is related to a lack of calcium.Lecture 6 (March 10)Resistance Training is the only exercise mode that the body can adapt to with only a single exposure. 6 months of resistance training can increase strength up to 100%.- Muscle Strength – maximal force that a muscle can generate- Muscle Power – measure of how quickly one can move a fixed force- Muscle Endurance – ability to maintain a near maximal muscle forceGeneral Training Principles include individuality, specificity, reversibility, progressive overload, and variation. In order to make improvements and strength gains, one has to continue to overload oneself by constantly increasing weights or pace to continue to see progress.Periodization is a cycle that athletes typically go through and is made up different cycles – a macrocycle, mesocycle, microcycle. It is also made up of different periods – a preparatory, first transition, competition period, and second transition period.- Macrocycle – an entire training year; the whole periodization cycle.- Mesocycle – two or more cycles within a macrocycle- Microcycle – typically one week long but it depends on the programResistance Training Program DesignMust to consider the athlete’s specific sport or event or goals – the exercise movements should be specific to the athlete. Must consider the major muscle groups – the large muscles are normally trained before the smaller muscles. Must consider the type of training for the desired outcome – the number of sets, resistance, repetitions, and velocity should be considered. Must consider injury prevention – the athlete must have adequate rest.Strength Training Exercise Categories:- Isometric/Static – muscle is at constant length and is anything that you hold. o Ex. plank- Isotonic/Dynamic – a constant load where you have the eccentric and concentric phases.o Ex. bicep curl-