INTRODUCTION. Objectives

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1 Objectives Functional Anatomy for Fitness Professionals focuses on functional anatomy, with an emphasis on weight training. Through the emphasis on biomechanics, neurology, and muscle physiology, participants will gain an understanding that goes beyond origin and insertion, and reps and sets. After completing the course, you will now be able to describe the function of upper and lower extremity based on anatomy, biomechanics, and physics. In addition to introduction, there are 6 modules, which can be completed in any order. Shoulder Girdle Shoulder (Glenohumeral) Elbow Hip Knee Ankle Included with each module are the related muscles. There are also research tidbits for each muscle. You will be updated regularly on the latest research as it applies to exercise and weight training.

2 Classification of Muscles Based on Function Muscles may also be categorized according to their role while producing the movement. Agonist (prime mover) A muscle that causes a specific movement (or several movements) via its own contraction. Antagonist A muscle that opposes the movement (or movements) caused by the agonist. Synergist A muscle the performs or helps to perform the movement (or movements) caused by the agonist. Neutralizing (counter-acting) synergists prevent unwanted movement produced by the prime mover. Stabilizing (fixating) synergists, on the other hand, prevent or control movement at joints proximal to the moving joint. In the next section, antagonists and synergists will be labeled as (A) and (S), respectively.

3 Tonic and Phasic Musculature I would like to introduce you to taxonomy for muscle classification. Again, this classification schema is based on muscle fibre characteristics, but also on muscle architecture. Tonic and phasic muscle theory takes into account the body s inherent design. That is, it relates to function. The beauty of this theory and its application is allows to avoid cook-book approaches in program design and assessment. Rather it fosters a problem-solving, individualistic approach. Dr. Vladimir Janda, the renowned Czechoslovakian physician coined the term tonic and phasic in the late 1960 s. Based on EMG and clinical studies, he found that certain muscles, which he termed tonic, had an antigravity function. These muscles had a higher resting tonus as they were constantly active. In fact, these muscles were founded to have a shorter than normal resting length. Tonic muscles are predominately type I or slow-twitch fibres. They consist of many mitochondria and thus, their oxidative capacity is quite high. More importantly, however, is that they are innervated by small, alpha a2 motor nerves. In other words, they are easily stimulated. This characteristic is important as these muscles must receive constant messages in order to control and correct posture. With this, comes a down side. Due to their relative ease of activation, these muscles are constantly firing, resulting in short, tight muscles. Phasic muscles, on the other hand, were under voluntary control, but did not respond to gravity. Unlike their tonic counterparts, these muscles were prone to inhibition and weakness Phasic muscles, on the other hand, consist mainly of type II or fast-twitch fibres. Due to their innervation by large, alpha a1 motor nerves, they require more stimulation to become active. Once activated, however, they have a greater capacity for force generation, but fatigue easily. This class of muscle is not designed to take on a postural or endurance role. Dysfunction of phasic muscles is manifested by weakness and inhibition. Short, tight tonic muscles often lead to weak, flaccid phasic muscles. For example, in Lower crossed syndrome, again coined by Janda in 1994, is characterized by tight hip flexors (iliopsoas) and lumbar spine erectors, and weak abdominals and gluteals. Upper crossed syndrome involves a tight pectoralis minor and posterior cervical extensors, and weak rhomboids and deep cervical flexors. (For a complete list of tonic and phasic muscles, refer to Table 1.) With this being said, muscles no longer need to be randomly stretched and/or strengthened. Weak (phasic) muscles often remain weak despite the best attempts at strengthening them. This is usually due to their tight antagonist muscle, which is usually tonic. These short, tight antagonist muscles need to be lengthened prior to strengthening these weak muscles. Furthermore, phasic muscles rarely need to be stretched as they are already inhibited.

4 Tonic and Phasic Musculature Table 1. Tonic and Phasic Musculature Tonic Iliopsoas Rectus Femoris Hamstrings Piriformis Tensor Fascia Latae Gastrocnemius Soleus Upper Trapezius Pectoralis Major Pectoralis Minor Levator Scapula Bicep Brachii Subscapularis Phasic Gluteus Maximus Gluteus Medius Vasti (Medialis/Lateralis) Tibialis Anterior Fibularis Rhomboids Middle and Lower Traps Tricep Brachii Deltoid Supraspinatus Infraspinatus Rectus Abdominus Obliques Transversus Abdominus Table 2. Characteristics of Tonic and Phasic Muscles Tonic Phasic Prone to hyperactivity Prone to inhibition Function Posture Movement Susceptibility to Fatigue Late Early Reaction to Faulty Loading Shortening Weakening

5 Spurt and Shunt Musculature The other taxonomy used to classify muscles is the based on muscle architecture. A spurt muscle is a muscle that possesses a line of pull across a joint such that it favours rotary force or torque. Another characteristic is that the distal attachment is close to the joint at which the muscle acts resulting in a greater rotatory component compared with its stabilizing component. A shunt muscle is a muscle that has a line of pull that is oriented predominantly along the long axis of a bone (thus mostly a joint stabilizing force). These shunt muscles have their more proximal attachment close to the joint, and their action is said to be more for stabilization than for rotation The biceps brachii muscle is often presented as an example of a spurt muscle and the brachioradialis muscle as an example of a shunt muscle. Table 3. Spurt and Shunt Muscles Spurt Adductors Biceps Brachii Gastrocnemius Hamstrings Sartorius Soleus Tibialis Anterior Shunt Brachialis Deltoids Gluteus Maximus Gluteus Medius Infraspinatus/Teres Minor Lateral Rotators of Hip Latissimus Dorsi Pectoralis Major Due to the duel nature of certain muscles, they remain unclassified.

6 Phase Shift The third concept I would like to explore is one of the phase shift. First coined by the human anatomist, David Gorman, it refers to the ability of a two-joint muscle to retain its resting length while performing complex functions. Why is this important, and secondly, what are examples of it? To answer the first question, one must understand the relationship between length of a muscle and force production. This is known as the length-tension relationship, and can be described as follows: The force output of a muscle varies (with the same neural input) over a range of lengths. The reasons for this variation include a change in the number of possible active sites for cross-bridge formation and the effect of the elastic tissues that are in parallel with the contractile tissue. A typical tension-length curve for human muscle is shown in the following figure. It is estimated that a muscle is strongest at approximately 120% of its resting length. A muscle too short or too long will be weak. Muscles thus adapt a strategy to maximize their efficiency and prevent injury the phase shift. Below are a few examples of this phenomenon: Squats On the descent, the rectus femoris shortens over the hip joint and lengthens at the knee joint. Concurrently, the hamstrings are lengthening over the hip joint and shortening at the knee joint. During the ascent, the opposite occurs. The rectus femoris lengthens over the hip joint and shortens at the knee joint. Conversely, the hamstrings are shortening and lengthening at the hip and knee, respectively. Close-Grip Bench Press During the concentric portion, the triceps brachii lengthen at the shoulder (glenohumeral) joint and shorten at the elbow. The biceps brachii, on the other hand, shortens at the shoulder joint and lengthens at the elbow. During the negative, the triceps shorten at the shoulder and lengthen at the elbow. The biceps now lengthen at the shoulder and shorten at the elbow.