Health, Fitness, & Nutrition
by Scott Massey


Since you are reading this newsletter you are probably involved in some sort of physical activity on a fairly regular basis. In the long run, the old adage of ‘what you put in is what you get out’, possess a great deal of truth. The more intense the training the more benefit it will provide. However, if you’re ‘sucking wind’ ten minutes into a Muay Thai class, then the training that you are getting may not help you much.


So, what are some efficient, effective ways to better your overall physical performance? This column hopes to provide some suggestions that you can follow in order to improve your current conditioning level. This first article will address the systems that produce energy for various activities and what types of training best suits these systems. These concepts will be different than basic fitness activities, so bear with me.


Initially, any movement is caused and controlled by a neurochemical reaction at the neuromuscular junction, proceeding into the muscle fibers. This causes the muscle to contract (the actual action and response is more complex but for the sake of space and time...). The fuel that the muscles use initially for this ‘sort twitch’ comes from the Phosphagen system. Any movement that is explosive, (the clean and jerk, rebounding a basketball, plyometric drills, etc.) generally use this system. While it initiates all movement, including marathon running, depletion of phosphagen stores occurs within a few seconds.

After the Phosphagen system has performed its function, energy production via the ATP-CP system occurs. ATP-CP, Adenosine Triphosphate - Creatine Phosphate, is the primary fuel for the muscle tissue. The act of muscular contraction is in fact impossible with out ATP. Most movements that are primarily ATP-CP driven are relatively short in duration, less than three minutes long, and are generally of lower intensity than those movements produced by the phosphagen system. ATP-CP muscular contractions can produce much more force (muscular force production is inversely related to the speed of muscular contraction) than the previous systems. Some typical types of movements utilizing ATP-CP are power lifting movements, basic bodybuilding movements, and other activities that display lower intensities and longer durations than an explosive movement.

Generally speaking, the overlap from the ATP-CP system to the next level, the Lactic Acid system, starts around the second minute of activity. Now wait a minute, isn’t lactic acid what causes my muscles to burn and makes me stop working out? Yes, to a point. Usually when lactic acid buildup occurs because the intensity of the movement has been too intense for that period of time. The buildup of lactic acid has overloaded what is called the Krebs Cycle (which is the continuation of glycolysis, which started around the fourth second of a movement) in which pyruvic acid created by glycolysis is converted into another sustrate, acetyl-CoA, for use within the Krebs Cycle. In short, you’ve flooded your engine, and the vehicle has to stop (ATP-CP and its function of causing muscular contraction has difficulty occurring in a low PH, acidic, environment).

Lactic Acid is an important substrate in that it aids in the continuation of the metabolic processes providing energy during prolonged bouts of exercise. Activities that engage the Lactic Acid system are longer in duration than explosive movements and force movements, include such activities as wrestling, 400 - 800 meter track events, and certain bodybuilding exercises. This metabolic area is used extensively in other activities including boxing, Muay Thai, and stick fighting that are characterized by periods of inactivity followed by explosive, high powered bursts of activity.


Finally, the Oxidative system takes on the responsibility of energy production required for movement. This system, also referred to as Aerobic Metabolism, is also responsible for the continuation of energy release in the form of movement. The Aerobic, or Oxidative system, kicks in around three to five minutes after activity has begun. It is primarily used for long duration low intensity activities such as marathons, crew, and some cycling events. It also assists the recovery of each of the other systems.


The first task is to decide which energy system an athletic activity relies upon. (This is called a Needs Analysis, not to be confused with some people at the school who ‘Need Analysis’!) For most activities that we do in class, the Lactic Acid (LA) system seems to dominate. Remember that the LA system is characterized as supplying energy for short bursts of high intensity activity, followed by brief periods of relative inactivity.


A listing and analysis of the previously discussed power systems and their training methodology may be in order. This will help you better understand their uses and why they are important as well.


The Phosphagen system is responsible for supplying energy for explosive, power-intensive activities. To train this system, short duration activities of 5 - 15 seconds of high intensity is advised. ‘High intensity’ is defined as exerting greater than 90% of your maximum strength potential or 1 RM (Rep Max). Olympic lifts such as the ‘snatch’ and the ‘clean and jerk’ are excellent examples of this type of movement. Plyometric are also a good example of this type of training. Both activities are highly technical movements patterns and should be performed only after competent instruction and proper preconditioning periods.

The Adenosine Triphosphate-Creatine Phosphate (ATCP) driven movements are characterized by being longer in duration, greater than 15 seconds, but less than 90 seconds, and lower in intensity than the explosive movements. An example of this type of movement are general body building training programs of 3 - 5 sets of 6 - 10 repetitions at 80 - 85% of 1 RM is usually performed.


The Lactic Acid (LA) system is best stimulated by performing interval type training. This means that during a workout, short (less than 5 minute intermittent sections are devoted to sprint-level intensities, while the remainder of the workout is performed at a low to moderate level intensity. Circuit training with weights is an example of interval training. By moving rapidly from one movement or station to the next, this routine stimulates the same mechanisms as the interval-type workouts. By training in this fashion the lactic acid utilization / removal process is made more efficient.


Finally, the Oxidative or Aerobic system responds well to long periods of rhythmic, large muscle movement activities. Aerobics, running, and cross-country skiing are examples of this type of training. The most common way to determine the proper intensity level is by using the Target Heart Rate Zone (THRZ) method. This is acquired by using the following equation: 220 - (your age) - (your resting heart rate) x (.7) or (.9) + (your resting heart rate). This will give you your THRZ at 70% or 90% of your maximum heart rate. Training the oxidative system within your THRZ will increase the efficiency of oxygen utilization as well as decrease the recovery time needed after exercise.


All energy production within the physiological system is directly related to the intensity of the activity. Time / duration of the activity is also an important consideration; however, the intensity of the activity remains the primary determinant. Knowledge of these systems can help the athlete determine the type of training that best suits his or her activity (Needs Analysis) and how they train those systems for optimum performance.

* Note: Material for this article was obtained from various sources, include: Essentials of Strength Training and Conditioning, 1994, NSCA / Human Kinetics, Champaign, IL.

Scott Massey holds a B.S. in Kinesiology from the University of Maryland, is a member of the National Strength and Conditioning Association, and is a Certified Strength and Conditioning Specialist.

The Kutting Edge (MAK) Part 1 Nov - Dec '95 Part 2 Jan - Feb '96


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