Class 2-3: Muscular Fitness

Overview

Today's Class Overview

In today's class, you will learn about the structure of muscles, recommendations for safe and effective resistance training, and positive self-talk.

Today's Class Objectives

By the end of this module you should be able to:

1. Describe the basic physiology of the muscular system.
2. Plan an exercise routine following recommendations for safe and effective resistance exercise.
3. Determine how many repetitions of an exercise to perform for a desired adaptation.
4. Define and apply the concept of "self-talk."

Outline of Today's Class

• Materials
  • Overview
  • Review
  • The Muscular System
  • Resistance Training Recommendations
  • Repetitions and Sets
  • Self-Talk
  • Summary

Review

Reviewing 2-2: Cardiovascular Health

• Cardiovascular System
  • Heart, Blood Vessels, Lungs
  • Provides oxygen needed to help convert food into usable energy
• Three Major Energy Systems
  • Work together to provide energy
    • Oxidative (With oxygen) - 2 minutes or longer of activity
    • Anaerobic (Without oxygen) - 30 to 120 seconds of activity
    • Immediate (Creatine phosphate) - 10 - 20 seconds of activity
• ACSM Recommendations
  • Frequency: 3–5 days per week for healthy adults.
  • Intensity: moderate to vigorous intensity, which equals 40–85% of heart rate reserve, or 55–90% of percentage of max heart rate.
  • Time/duration: 20­­–60 minutes per session or accumulation of 150 minutes per week. Sessions must be continuous for 10 minutes or more.
  • Type/mode: Use large muscle groups and exercises specific to cardiorespiratory exercise.
• Heart Rate
  • Useful for tracking intensity of cardiovascular exercise using a target percentage of maximum heart rate.
• Rating of Perceived Exertion
  • Scale of perceived intensity
• Exposure to Nature
  • Linked to improved attention, lower stress, better mood, reduced risk of psychiatric disorders and even upticks in empathy and cooperation.

The Muscular System

The following has been excerpted and adapted from Concepts of Fitness and Wellness, 2nd Edition, Georgia Highlands College (CC BY-NC-SA):

Skeletal Muscle Structure and Function

Skeletal muscles are attached to the skeleton and are responsible for the movement of our limbs, torso, and head. They are under conscious control, which means that we can consciously choose to contract a muscle and can regulate how strong the contraction actually is. Skeletal muscles are made up of a number of muscle fibers. Each muscle fiber is an individual muscle cell and may be anywhere from 1 mm to 4 cm in length. When we choose to contract a muscle fiber—for instance we contract our bicep to bend our arm upwards—a signal is sent from our brain via the spinal cord to the muscle. This signals the muscle fibers to contract. Each nerve will control a certain number of muscle fibers. The nerve and the fibers it controls are called a motor unit. Only a small number of muscle fibers will contract to bend one of our limbs, but if we wish to lift a heavy weight then many more muscles fibers will be recruited to perform the action. This is called muscle fiber recruitment.

Each muscle fiber is surrounded by connective tissue called an external lamina. A group of muscle fibers are encased within more connective tissue called the endomysium. The group of muscle fibers and the endomysium are surrounded by more connective tissue called the perimysium. A group of muscle fibers surrounded by the perimysium is called a muscle fasciculus. A muscle is made up of many muscle fasciculi, which are surrounded by a thick collagenous layer of connective tissue called the epimysium.

The epimysium covers the whole surface of the muscle.

Muscle fibers also contain many mitochondria, which are energy powerhouses that are responsible for the aerobic production of energy molecules, or ATP molecules. Muscle fibers also contain glycogen granules as a stored energy source, and myofibrils, which are threadlike structures running the length of the muscle fiber. Myofibrils are made up of two types of protein: 1) Actin myofilaments, and 2) myosin myofilaments. The actin and myosin filaments form the contractile part of the muscle, which is called the sarcomere. Myosin filaments are thick and dark when compared with actin filaments, which are much thinner and lighter in appearance. The actin and myosin filaments lie on top of one another; it is this arrangement of the filaments that gives muscle its striated or striped appearance. When groups of actin and myosin filaments are bound together by connective tissue they make the myofibrils. When groups of myofibrils are bound together by connective tissue, they make up muscle fibers.

The ends of the muscle connect to bone through a tendon. The muscle is connected to two bones in order to allow movement to occur through a joint. When a muscle contracts, only one of these bones will move. The point where the muscle is attached to a bone that moves is called the insertion. The point where the muscle is attached to a bone that remains in a fixed position is called the origin.

How Muscles Contract

Muscles are believed to contract through a process called the Sliding Filament Theory. In this theory, the muscles contract when actin filaments slide over myosin filaments resulting in a shortening of the length of the sarcomeres, and hence, a shortening of the muscle fibers. During this process the actin and myosin filaments do not change length when muscles contract, but instead they slide past each other.

During this process the muscle fiber becomes shorter and fatter in appearance. As a number of muscle fibers shorten at the same time, the whole muscle contracts and causes the tendon to pull on the bone it attaches to. This creates movement that occurs at the point of insertion.

For the muscle to return to normal (i.e., to lengthen), a force must be applied to the muscle to cause the muscle fibers to lengthen. This force can be due to gravity or due to the contraction of an opposing muscle group.

Skeletal muscles contract in response to an electric signal called an action potential. Action potentials are conducted along nerve cells before reaching the muscle fibers. The nerve cells regulate the function of skeletal muscles by controlling the number of action potentials that are produced. The action potentials trigger a series of chemical reactions that result in the contraction of a muscle.

When a nerve impulse stimulates a motor unit within a muscle, all of the muscle fibers controlled by that motor unit will contract. When stimulated, these muscle fibers contract on an all-or-nothing basis. The all-or-nothing principle means that muscle fibers either contract maximally along their length or not at all. Therefore, when stimulated, muscle fibers contract to their maximum level and when not stimulated there is no contraction. In this way, the force generated by a muscle is not regulated by the level of contraction by individual fibers, but rather it is due to the number of muscle fibers that are recruited to contract. This is called muscle fiber recruitment. When lifting a light object, such as a book, only a small number of muscle fibers will be recruited. However, those that are recruited will contract to their maximum level. When lifting a heavier weight, many more muscle fibers will be recruited to contract maximally.

When one muscle contracts, another opposing muscle will relax. In this way, muscles are arranged in pairs. An example is when you bend your arm at the elbow: you contract your bicep muscle and relax your tricep muscle. This is the same for every movement in the body. There will always be one contracting muscle and one relaxing muscle. If you take a moment to think about these simple movements, it will soon become obvious that unless the opposing muscle is relaxed, it will have a negative effect on the force generated by the contracting muscle.

A muscle that contracts, and is the main muscle group responsible for the movement, is called the agonist or prime mover. The muscle that relaxes is called the antagonist. One of the effects that regular strength training has is an improvement in the level of relaxation that occurs in the opposing muscle group. Although the agonist/antagonist relationship changes, depending on which muscle is responsible for the movement, every muscle group has an opposing muscle group.

Smaller muscles may also assist the agonist during a particular movement. The smaller muscle is called the synergist. An example of a synergist would be the deltoid (shoulder) muscle during a press-up. The front of the deltoid provides additional force during the press-up; however, most of the force is applied by the pectoralis major (chest). Other muscle groups may also assist the movement by helping to maintain a fixed posture and prevent unwanted movement. These muscle groups are called fixators. An example of a fixator is the shoulder muscle during a bicep curl or tricep extension.

Types of Muscular Contraction

• Isometric
  • This is a static contraction where the length of the muscle, or the joint angle, does not change. An example is pushing against a stationary object such as a wall. This type of contraction is known to lead to rapid rises in blood pressure.
• Isotonic
  • This is a moving contraction, also known as dynamic contraction. During this contraction the muscle fattens, and there is movement at the joint.
• Concentric
  • This is when the muscle contracts and shortens against a resistance. This may be referred to as the lifting or positive phase. An example would be the lifting phase of the bicep curl.
• Eccentric
  • This occurs when the muscle is still contracting and lengthening at the same time. This may be referred to as the lowering or negative phase.

Muscle Fiber Types

Not all muscle fibers are the same. In fact, there are two main types of muscle fiber:

• Type I
  • Often called slow-twitch or highly-oxidative muscle fibers
  • Slow-twitch muscle fibers contain more mitochondria, the organelles that produce aerobic energy.
  • They are also smaller, have better blood supply, contract more slowly, and are more fatigue resistant than their fast-twitch brothers.
  • Slow-twitch muscle fibers produce energy, primarily, through aerobic metabolism of fats and carbohydrates.
  • The accelerated rate of aerobic metabolism is enhanced by the large numbers of mitochondria and the enhanced blood supply.
  • They also contain large amounts of myoglobin, a pigment similar to hemoglobin that also stores oxygen.
  • The myoglobin provides an additional store of oxygen for when oxygen supply is limited.
  • This extra oxygen, along with the slow-twitch muscle fibers’ slow rate of contraction, increases their endurance capacity and enhances their fatigue resistance.
  • Slow-twitch muscle fibers are recruited during continuous exercise at low to moderate levels.
• Type II
  • Often called fast-twitch or low-oxidative muscle fibers
  • These fibers are larger in size, have a decreased blood supply, have smaller mitochondria and less of them, contract more rapidly, and are more adapted to produce energy anaerobically (without the need for oxygen) than slow-twitch muscle fibers.
  • Their reduced rate of blood supply, together with their larger size and fewer mitochondria, makes them less able to produce energy aerobically, and are therefore, not well suited to prolonged exercise.
  • However, their faster rate of contraction, greater levels of glycogen, and ability to produce much greater amounts of energy anaerobically make them much more suited to short bursts of energy.
  • Because of their greater speed of contraction and reduced blood supply, they are far less fatigue resistant than slow-twitch fibers, and they tire quickly during exercise.

The number of slow and fast-twitch fibers contained in the body varies greatly between individuals and is determined by a person’s genetics. People who do well at endurance sports tend to have a higher number of slow-twitch fibers, whereas people who are better at sprint events tend to have higher numbers of fast-twitch muscle fibers. Both the slow twitch and fast-twitch fibers can be influenced by training. It is possible through sprint training to improve the power generated by slow twitch fibers, and through endurance training, it is possible to increase the endurance level of fast-twitch fibers. The level of improvement varies, depending on the individual, and training can never make slow-twitch fibers as powerful as fast-twitch, nor can training make fast-twitch fibers as fatigue resistant as slow-twitch fibers.

For more information on muscle physiology, click on the links below:

Skeletal Muscle Physiology

Fast Twitch versus Slow Twitch

Skeletal Muscles

Resistance Training Recommendations

The following has been excerpted and adapted from Concepts of Fitness and Wellness, 2nd Edition, Georgia Highlands College (CC BY-NC-SA):

Resistance Training Recommendations

• Perform a minimum of 8 to 10 exercises that train the major muscle groups.
• Workouts should not be too long. Programs longer than one hour are associated with higher dropout rates.
• Choose more compound, or multi-joint exercises, which involve more muscles with fewer exercises.
• Perform one set of 8 to 12 repetitions to the point of volitional fatigue for each major movement or body area.
  • More sets may elicit slightly greater strength gains, but additional improvement is relatively small.
    Perform exercises at least 2 days per week.
• More frequent training may elicit slightly greater strength gains, but additional improvement is relatively small since progress is made during the recuperation between workouts.
• Adhere as closely as possible to the specific exercise techniques.
• Perform exercises through a full range of motion.
  • Elderly trainees should perform the exercises in the maximum range of motion that does not elicit pain or discomfort.
• Perform exercises in a controlled manner.
• Maintain a normal breathing pattern.
• If possible, exercise with a training partner.
  • Partners can provide feedback, assistance, and motivation.

Exercise Order for Resistance Training

The general guidelines for exercise order when training all major muscle groups in a workout is as follows:

Large muscle group exercises (i.e., squat) should be performed before smaller muscle group exercises (i.e., shoulder press).

• Multiple-joint exercises should be performed before single-joint exercises.
  
• For power training, total body exercises (from most to least complex) should be performed before basic strength exercises. For example, the most complex exercises are the snatch (because the bar must be moved the greatest distance) and related lifts, followed by cleans and presses. These take precedence over exercises such as the bench press and squat.
• Alternating between upper and lower body exercises or opposing (agonist–antagonist relationship) exercises can allow some muscles to rest while the opposite muscle groups are trained. This sequencing strategy is beneficial for maintaining high training intensities and targeting repetition numbers.
• Some exercises that target different muscle groups can be staggered between sets of other exercises to increase workout efficiency. For example, a trunk exercise can be performed between sets of the bench press. Because different muscle groups are stressed, no additional fatigue would be induced prior to performing the bench press. This is especially effective when long rest intervals are used.³

Resistance Training Conclusion

The most effective type of resistance-training routine employs a variety of techniques to create a workout program that is complete and runs the gamut, from basic to specialized. Learning different methods of training, different types of resistance, and the recommended order can help you acquire a balanced, complete physique. That does not mean that these training methods will help everybody to win competitions, but they will help you learn how to tune in to your body and understand its functions through resistance and movement. This knowledge and understanding develops a valuable skill, allowing you to become more adept at finding what works best for you on any given day.

Repetitions and Sets

Understanding repetition ranges lets us know how many times to do an exercise to get the benefit we are looking for.

Recall that "stress" is any stimulus that causes a change, and that how "stressful" something is depends on our ability.

With exercise, the specific changes we will see depend on those F.I.T.T. elements and our current level of ability.

The "repetition range" is the number of times we can do an exercise before fatigue, before we have to stop.

Choosing the correct repetition range for strength, muscle growth (hypertrophy), or endurance is an important aspect of a realistic approach to exercise.

• 1-3 maximum repetitions before unable to do any more results primarily in POWER improvements.
• 4-8 maximum repetitions before unable to do any more results primarily in STRENGTH improvements.
• 8-12 reps maximum repetitions before unable to do any more results primarily in SIZE improvements.
• 12-20 or more maximum repetitions before unable to do any more results primarily in ENDURANCE improvements.

To Learn More

To learn more about how to set up a muscular fitness plan, the National Strength and Conditioning Association has a comprehensive "Basics of Strength and Conditioning Manual" available for free download.

Self-Talk

Visit this website on self-scripting from the University of North Carolina at Chapel Hill’s Learning Center to learn more about the importance of self-talk.

Summary

Major Points

During today's class, you have learned:

• Basic muscle physiology
  • Skeletal muscles are made up of a number of muscle fibers.
• Resistance Training Recommendations
  • Perform exercises at least 2 days per week.
  • Perform a minimum of 8 to 10 exercises that train the major muscle groups.
  • Choose more compound, or multi-joint exercises, which involve more muscles with fewer exercises.
  • Perform one set of 8 to 12 repetitions to the point of volitional fatigue for each major movement or body area.
    • More sets may elicit slightly greater strength gains, but additional improvement is relatively small.
      
  • Progress is made during the recuperation between workouts.
  • Perform exercises through a full range of motion.
  • Perform exercises in a controlled manner.
  • Maintain a normal breathing pattern.
• Exercise Order
  • Large muscle groups and more muscle groups before smaller and fewer ones.
• Choosing the correct repetition range for strength, muscle growth (hypertrophy), or endurance is an important aspect of a realistic approach to exercise.
  • 1-3 maximum repetitions before unable to do any more results primarily in POWER improvements.
  • 4-8 maximum repetitions before unable to do any more results primarily in STRENGTH improvements.
  • 8-12 reps maximum repetitions before unable to do any more results primarily in SIZE improvements.
  • 12-20 or more maximum repetitions before unable to do any more results primarily in ENDURANCE improvements.
• Self-Talk - Internal Dialogue
  • Most helpful when it is positively focused, accurate, and realistic.
  • Unhelpful self-talk tends to be negative, inaccurate, or unrealistic.