/ath/ - Athletics

> 1. Training Theory: Basic Concepts

The main focus behind any systematic exercise is progression. A properly structured routine will result in an athlete improving in their discipline over time. This is accomplished through the biological law of adaptation - the adjustment of an organism to the stresses in its environment.

In sport, the athlete adapts to the stresses they're placed under. 4 aspects of adaptation that are especially important for training are:

1. Overload
2. Accommodation
3. Specificity
4. Individualization

< Overload (Magnitude of Stimulus)
Bringing about positive adaptations in an athlete requires a stimulus that is above habitual levels. There are two ways to increase the magnitude of stimulus: increasing the training load (increasing volume or intensity), or changing the exercise (given less accommodation). 

< Accommodation
As athletes are repeatedly exposed to the same stimulus, their adaptation response decreases with each successive exposure. This is considered a general law of biology, where the response of a biological object to a constant stimulus decreases over time. This makes the principle of diminishing returns a consideration in sports training for when athletes are adapted enough to a stimulus that increased levels bring little appreciable adaptation.

< Specificity
Training adaptations are highly specific. Strength training increases muscle mass and strength. Endurance training induces increases in aerobic capacity and increased blood volume. For sport training to be successful, exercise that mirrors the general conditions of the specific sport should be used. 

< Individualization
Everyone reacts to stimulus in their own way. Basically be flexible with it, find your groove and what fits you.

These factors are the most basic building blocks of exercise planning, and answer the most rudimentary questions in building a routine (what kind of exercises should I do, how much should I do, and what will this achieve?). Remember, progression is the hallmark of a successful exercise routine. Always think of how you will progress.

> 1. Training Theory - Generalized Training Theories

Generalized training theories are simple models used by coaches and athletes to help plan and visualize training programs and conditioning. These models are very broad, and are used as a general tool to explain how performance manifests.

Two practical and effective training theories are supercompensation theory, and fitness-fatigue theory:

< Supercompensation Theory
In supercompensation theory, an athletes preparedness to train is purported to be tied directly to how much biochemical substrate is available for the muscles to use. During strenuous exercise, substrates are depleted, and after rest, replenish past their original levels. This is known as supercompensation. The time where substrates are replenished above original levels is known as the supercompensation phase. Efficient application of supercompensation theory would mean that workouts are timed to fall at the peak of the supercompensation phase. While this model works in practice, it has fallen out of favor as more critical analysis of the mechanisms behind metabolism have raised criticisms of the theory's explanation of fatigue.

< Fitness-Fatigue Theory
Fitness fatigue theory of training includes three variables. Gain in fitness from adaptation, deterioration from fatigue, and net performance. Performance is the net balance between fitness gain, and deterioration from fatigue. Immediately after a workout (stimulus), fatigue is high, far outracing fitness gains. However as fatigue dissipates, and the athletes fitness adaptations manifest, performance rises. Efficient use of fitness-fatigue theory would see workouts being held at the peak of preparedness, shown as the highest net gain between fitness and fatigue.

For more information on training theory, check here: https://archive.is/PKpsU 

> 2. Muscle: Structure and Function

Skeletal muscle-- one of the three major muscle types: cardiac, skeletal, and smooth-- is striated muscle tissue under voluntary control of the somatic nervous system.

< Basic Structure
A muscle cell, or a myocyte, is the basic building block of striated muscle tissue. They are composed of myofibrils, bundles of sarcomeres-- long fibrous protein filaments-- which slide past each other to contract or relax during intracellular chemical reactions. Sarcomeres are linked end to end creating long chains, and banded together to form myofibrils. These myofibrils are further bound together to form muscle fiber. 

< Non-Muscular Structures
The fibers and muscle are surrounded by connective tissue called fascia, which attaches, stabilizes, and encloses the muscle, and reduces friction of muscular force.

Tendons attach the muscles to bone, and transmit muscular force. This transmitted muscular force produces torque at the joints, which we use to produce intended movement.

< Mechanism
The mechanism behind a muscle cell contraction involves the triggering of a chemical reaction within the cell that leads to a shortening of muscle fiber. For intracellular reactions to occur properly, certain conditions must be met-- such as proper PH range, substrate availability, and electrolyte balance. 

By definition, electrolytes are a substance that produces a conductive solution when dissolved in a polar solvent (like water). In physiology, electrolytes are critical for regulating nerve and muscle function. The most important electrolytes for physical activity are sodium- the main electrolyte in extracellular fluid- and potassium, the main intracellular electrolyte.

Myocytes are actually one of the larger cells in our bodies. A single link of sarcomeres can actually be seen with the naked eye. Take a frayed piece of beef jerky and hold it up to a light, looking for the smallest, skinniest strand coming off the surface. That is a single strand of linked sarcomeres.

> 2. Muscle: Types of Contractions


In physiology, muscle contraction is not synonymous with muscle shortening. Muscles can be contracting without a change in muscle length, such as when holding a heavy object. The variables that describe muscle contractions are length, and tension. Additionally all contractions produce some damage to muscle cells due to the chemical and mechanical stress they endure (which is part of what you adapt to).

Muscle contractions can be broadly classified into two types:

< Isometric Contractions

In isometric contractions, muscle length stays constant while muscle tension is increased. Isometric muscle contraction is present in static exercises, such as planks.

< Isotonic Contractions

Isotonic contractions can be further categorized into two groups:

Concentric Contractions 
Occur when tension remains constant as muscle length shortens. For example pushing a barbell up during a bench press, or pulling yourself up on a pullup bar.

Eccentric Contractions
Occur as muscle length increases while muscle tension remains constant. This can be thought of as decelerating action, such as lowering yourself from a pull up bar. The mechanism through which muscle cells produce force in eccentric contractions is different than  isometric and concentric contractions, and not currently understood. This different mechanism allows eccentric contractions to be 40% stronger than concentric, however with significantly more cellular damage. This difference is thought to be why delayed onset muscle soreness (DOMS) is so prevalent with eccentric exercises. The body can adapt to eccentric contractions with proper training, resulting in significantly less damage cellular damage and DOMS.

< Auxotonic Contractions (non-isometric, non-isotonic)

Most exercises have fluctuation in muscle tension, and the contractions involved could technically be classified as auxotonic. Auxotonic contractions occur when both muscle tension and length changes. 

For fitness purposes, there's generally no need to differentiate between isotonic and auxotonic contractions. However it may be useful to think about auxotonic contractions when it comes to exercise selection or carryover and the change in muscle tension throughout the movement.

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> 2. Muscle: Fiber Type

Skeletal muscle can be classified into two different types. Within these types, there are multiple different classifications of fiber with specialized characteristics. Fiber type distribution throughout the body is determined by genetics. These two groups are:

< Slow Twitch (Type I)
Slow twitch muscle fiber is specialized in producing force for an extended period of time. Some characteristics of type I fiber are a high resistance to fatigue, low force production, and slow contraction speed. Slow twitch cells also have high concentration of mitochondria and capillaries to support energy production through aerobic respiration (metabolism in a later section).

< Fast Twitch (Type II)
Fast twitch fiber can be further split into two main types, type IIa and type IIb.

Type IIa
IIa fiber holds characteristics intermediate to type I and type IIb. Type IIa is moderately resistant to fatigue, produces an intermediate amount of force, and has a fast contraction speed. It also has moderate concentrations of mitochondria and capillaries, and increased stores of glycogen-- obtaining fuel through both aerobic and anaerobic means.

Type IIb
IIb fiber is specialized in creating a large amount of force. Characteristics of IIb fibers are a low resistance to fatigue, high force production, and a very fast contraction speed. Type IIb fibers have low concentrations of mitochondria and capillaries, getting much of their energy through anaerobic metabolism.

Latest research further differentiates fast twitch fibers, adding a third type IIx. In reality, characteristics of the fiber types aren't quite as clear cut as is presented. For a more in depth discussion, see Ernest Maglischo-- a nationally acclaimed swim coach and PHD holder in exercise physiology-- discuss fiber types and training: https://youtube.com/watch?v=lUGuc06M39M [Embed] 

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> 2. Muscle: Training Adaptations

Consistent exercise brings about many adaptations in muscle cells. Some of the most obvious adaptations include increased strength, endurance, and size.

< Muscular Hypertrophy
An increase in muscle size is known as muscular hypertrophy. Hypertrophy can be classified into two different types:

Myofibrillar Hypertrophy
Occurs as a result of an increase in cell contractile tissue. The increased contractile tissue leads to an increase in force production. This type of adaptation is typical of high intensity (heavy weight), low repetition training.

Sarcoplasmic Hypertrophy
Occurs as a result of an increase in metabolic fuel (glycogen) and fluids stored in the cell. Muscle size increase is also more dramatic than in myofibrillar hypertrophy. This type of adaptation is typical of high volume, low intensity training.

< Regional Hypertrophy
Originally thought not to occur, studies from the past two decades indicate that regional hypertrophy--or non uniform development of a muscle fiber-- does occur. Although not fully understood, it is thought that such development may be caused by uneven distribution of skeletal muscle type throughout muscle fiber. Another theorized cause is muscle fiber being innervated by separate branches of nerves at different points, with partial activation of the fiber at different ranges of motion.

It is possible that regional hypertrophy contributes to why strength gains are joint angle specific (strength gains don't transfer well outside of the range of motion you train), although this may be due to neurological factors. Regardless, it might hold some bearing on exercise selection when considering movements with exaggerated auxotonic contractions.

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> 2. Muscle: Activation and Neural Factors

The nervous system is extremely important in the use and development of muscular strength. Strength is determined not only by quantity of muscle mass but also the extent of which individual fibers in a muscle are activated. Elite athletes have superior coordination in activating single muscles and muscle groups due to adaptations of their nervous systems.

< Motor Units
Are the basic elements of motor system output. Each MU consists of a motoneuron on the spinal cord, and the muscle fibers it innervates. A long axon connects the motoneuron to the muscle, where it branches out to innervate individual muscle fibers. When a motoneuron is active, impulses are distributed to all connecting muscle fibers. In small muscles, motoneurons may connect to a dozen muscle fibers, affording precision movement. In large muscles, motonuerons may connect to thousands of fibers.

Like the muscle fiber they attach to, motor units can be classified as fast twitch or slow twitch. Slow twitch motor units have a low threshold to being activated, while fast twitch motor units have a high threshold to activation. Motor units are activated to the all-or-none law, where at any point in time a motor unit is either active, or inactive.

The nervous system varies force production through three variables: recruitment of motor units, changing the firing rate of motor units, and activating motor units in a synchronized fashion.

Recruitment
During voluntary contractions, the pattern of recruitment is controlled by the size of motoneurons. Small motoneurons with low firing thresholds are recruited first, with demands for higher force production being met with the recruitment of increasingly forceful motor units. The motor units with the largest motoneurons, which have the largest and fastest contractions, are recruited last. Because of their low firing threshold, slow twitch fibers are recruited for all movement regardless of force production.

Firing Rate
The other primary mechanism for gradiating muscle force is through the firing rate of the motor neuron. This firing rate can vary over a considerable range. In small muscles, most motor neurons are recruited by the 50% point of maximal force production, with the remaining 50% coming from an increase in firing rate. Larger muscles sees the top 20% of maximal force production come from increased motor unit firing rate.

Synchronization
Normally motor units work asynchronously to produce smooth accurate movement. There is evidence in elite athletes however, of their motor units synchronizing under voluntary maximal efforts.

Nueral adaptation to training is often reffered to as neural efficiency. Gains in nueral efficiency are an important part in gaining and displaying strength. An untrained individual is incapable of activating a large percentage of their fast twitch fiber because they lack the neural adaptations to do so.