Adenosine Triphosphate (ATP): Adenosine + P + P + P.  The high energy molecule responsible for the sustainability and existence of all life forms.  Think of ATP as the international energy currency for all the cells in your body.  In order for our bodies to function we need ATP.  We generate ATP through eating food (carbohydrates, fats, and proteins).  After we have digested our food the nutrients go into the cells that need energy and these nutrients are broken down further via complex pathways (glycolysis or oxidation) to finally result in ATP.  To release the energy from ATP, we break one of the phosphate bonds attached to adenosine and energy is released!  AND this is the energy that drives ALL cellular processes.

  • Every time you contract a muscle the phosphate bonds in ATP are broken and energy is released allowing you to move.  In order to keep moving, you must continue contracting your muscles, so more ATP must be re-synthesized and more phosphate bonds broken.  The process of re-synthesizing ATP must be done via the anaerobic and aerobic energy pathways (ATP/CP cycle, anaerobic glycolysis, and oxidation).  When we stop re-synthesizing ATP we can’t continue cellular work and so we die.

Aerobic Endurance (cardio): the ability of your body to use oxygen to resynthesize ATP in order to perform dynamic muscle action involving large muscle groups for prolonged periods of time.  (walking, jogging, cycling, rowing, elliptical, swimming).

Assistance Exercise: generally a single joint exercise that involve a smaller muscle area and one joint: bicep curl/tricep extension, calf raises, low back extension, abdominal crunches.

Core Exercise: a multi-joint exercise that involves at least two joints and large muscle areas. For example: hip/knee (squat or lunge), back/shoulder/elbow (pullup or row), chest/shoulder/elbow (pushup).  Core exercises are selected by the strength coach as the most important to an individual’s training program, and must take priority over the other exercises.  The coach or trainer must analyze the individual’s needs and goals prior to selecting the core exercises.

Dynamic Muscle Actions: when a muscle contracts dynamically it pulls on the attached bone to move the respective joint by either increasing or decreasing the joint angle.  There are 2 two types of dynamic muscle action:

  • Concentric (shorten): the force developed when a muscle shortens and the joint angle decreases. The muscle is able to overcome the external resistance. For example, during the upward phase of the arm curl the bicep shortens and pulls on the bones of the forearm to flex the elbow thereby decreasing joint angle.
  • Eccentric (lengthen): the force developed when a muscle lengthens and the joint angle increases, this is occurring slowly against the force of gravity.  For example, during the down phase of the arm curl the bicep is lengthening and the angle at the elbow is increasing as the weight is being slowly lowered against the force of gravity. Another way to define eccentric action is the external resistance exceeds the muscle force and the muscle lengthens. For example, I am holding the top position in a pullup with my chin above the bar, you attach 50lbs around my waste and I can’t continue to hold myself with my chin above the bar I slowly try to resist the external load + gravity, but the resistance is too great and my muscles are lengthening so I’m returning back to the ground.

Explosive power: we can also call this Fast Speed Strength, and is the ability of a group of muscles to produce high levels of force at high velocities. Examples of explosive power are the Long-Jump, Vertical Jump.  When training for fast speed strength you must perform each repetition with maximal velocity and maximal force.  Repetitions should be NO MORE THAN 5 and sets can range from 2 – 5.  Sufficient rest periods between sets are essential for power development 3 to 5min.

Isometric Muscle Action: occurs when a muscle generates force but does not shorten because it can’t overcome the external resistance. For example, you put a 30lb dumbell in my hand and I attempt an arm curl but can’t flex my elbow more than 10°. In this situation my bicep is generating a force, but the external resistance (30lbs) is too great for my bicep to overcome. 

Motor Unit (MU): A motor unit is a motor neuron and all of the muscle fibers it innervates.  In all our muscles we have three types of motor units that are responsible for contraction and force production.  These are slow twitch or Slow Oxidative (SO), intermediate or Fast Oxidative Glycolytic (FOG), and fast twitch or Fast Glycolytic (FG). For a detailed explanation for each type see Skeletal Muscle Physiology.

  • The All or Nothing Principle: If a signal from the central nervous system (CNS) is sent to a motor neuron and this signal is at least 15-20mV then it is strong enough to create an action potential causing the motor neuron and ALL of its muscle fibers to depolarize –> causing these fibers to shorten.  Only the fibers innervated by the excited motor neuron will fire, so not all of the muscle fibers in that muscle will fire –> the number of motor units recruited, the rate and frequency of MU excitation depends on the intensity of the external demand and training status.
  • Principle of Orderly Recruitment and Size: During exercise motor units are recruited in direct proportion to the intensity of the exercise. During light exercise (light walking or light weights) you are recruiting your smallest motor units, the SO fibers.  As intensity increases more motor units get added on to help match the demand, these are the rest of the SO and the FOG. When the intensity is the highest or the heaviest loads you can tolerate then your FG motor units are now firing.   Example: You are running a marathon.  In the beginning you are fresh and the pace feels light so you’re primarily recruiting S.O. MU (type 1), as the miles drag on your SO fibers start dying out and so you have to recruit bigger fibers, the FOG.  By the last mile of the marathon, you are really fatigued because all your efficient slow twitch and intermediates are toast. By the last few miles you very fatigued because you have no other choice but to recruit the biggest, strongest, but least efficient FG fibers. 
  • In summary the size principle and orderly recruitment always goes like this: SO –> FOG –> FG. 
  • Unless you are a VERY well trained weight lifter and are performing a 1-RM (the maximal load you can lift 1x), you are able to preferentially recruit your strongest MU, the FG and bypass your slower MU.  

Muscular Endurance: the ability of a muscle or muscle group to repeatedly contract. This is a sub-maximal effort, for example timed push-ups in 1-minute is a test for muscular endurance of the pectoral muscles.  Muscular endurance can also be holding a position (isometric action) over time (30 – 120 sec), such as a plank.

Muscular Strength: the maximal force a muscle or group of muscles can produce in order to lift the heaviest load 1 time.  The heaviest load you can lift 1 time is also called the 1-repetition maximum (1RM).  In resistance training we base training intensity on the athlete’s 1RM for a variety of exercises that are specific to the athlete’s needs.  For example, in football the bench press is a core exercise so athletes will test their 1RM for bench press, and set their training loads off of a % of their 1RM (Athlete A: 1RM = 300lbs 80% of 300 = 240, so athlete A will perform his bench press at 240lbs).

Oxygen Consumption (VO2): the measurement of oxygen uptake by your cells in order to re-synthesize ATP to do cellular work. We can express VO2 in L/min (absolute) or ml/kg/min (relative).

  • VO2 Rest: at rest everyone consumes about 0.3 L/min or 3.5 ml/kg/min of oxygen to generate ATP.
  • VO2max: is the maximal ability of your cells to utilize oxygen to generate ATP.  This value is best indicator of MAXIMAL aerobic endurance performance.

Oxygen Deficit:The lag in VO2 at the beginning of steady state exercise at a constant workload.  Lets say you first get on the treadmill and turn the speed to a constant workrate of 5.0mph (assuming 5.0mph is an easy to moderate intensity for you).  In the graph below pay attention two lowest curves.  The easy-moderate curves shows what happens to your oxygen consumption (VO2) during the first few minutes of exercise.  Oxygen uptake rises exponentially for 1-2 minutes and then levels out despite still jogging at 5.0mph. The lag in VO2 occurs because you’re not resynthesizing ATP aerobically, rather you’re using ATP/CP and anaerobic glycolysis to regenerate ATP.  Eventually VO2 plateaus, this indicates you are now in your aerobic energy pathway, and despite being under moderate stress you are in a state of equilibrium (you feel comfortable and able to sustain the pace for awhile).

The lag in VO2 from easy to maximal exercise at a constant load.  During easy and moderate intensities the lag in VO2 is short and steady state VO2 can be achieved.  During “hard” and “severe” exercise the lag in VO2 is much greater, and steady state exercise cannot be achieved, rather oxygen consumption continues to rise gradually until it reaches maximum.  At maximal exercise the O2 deficit is highest and oxygen consumption ceases to rise indicating VO2max has been reached.

Progressive Overload: in order to increase in muscular strength, power, or aerobic endurance the body must gradually be placed under greater than normal demands.  It takes a week or two for the body to adapt to an exercise stimulus, after adaptation has occurred the body must be placed under greater stress to further fitness gains.

Sedentary death syndrome (SeDs): syndrome in which physical inactivity alone results in a variety of health conditions that eventually leads to premature death.

  • SeDS is related to many conditions including these: Obesity, high blood pressure, type II diabetes, heart disease, congestive heart failure, stroke.
  • SeDS will cause 2.5 million Americans to die prematurely in next decade.
  • SeDS will cost $2-3 trillion in health care expenses in US in next decade.
  • Type II diabetes has increased 900% since 1958.
  • US children now getting SEDS-related diseases (obesity, heart disease, type II diabetes).

Specific Adaptation to Imposed Demand (SAID): the more similar the exercise is to the actual sport movement, the greater the likelihood that there will be a transfer of skills to that sport.  The best way to become a faster cyclist is to pedal your bike a lot.  The best way to be able to knock someone down is to practice pushing heavy things a lot.

Structural and Power Exercises: any exercise that directly or indirectly loads the spine. For example the backsquat directly loads the spine, and the power clean indirectly loads it.  A power exercise is any structural exercise that is performed explosively.

One Response to Terminology

  1. Pingback: Pros and Cons of Strength Training to Failure | Molly Throdahl

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