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Sunday, August 20, 2017

Misinformation About Strength Training In The Army


























During my twenty years in the Army, misinformation regarding strength training was abundant. The military is transfixed on aerobic training. For many years, the military has promoted a singular concept in which all movement revolves around aerobic fitness. Science never seemed to enter the picture, until recently. Misinformation in the military is generally handed down from generations of leaders telling subordinates, of how it was done in the past. There was absolutely no knowledge of metabolic energy pathways, or of the need for anaerobic training to develop strength and power. After completing hundreds of long distance runs and countless high repetitions of exercises, the realization that performance transference existed, resonated with me to this day. Five mile runs did not provide any cardiorespiratory benefits, when the actual tasks involved picking up heavy objects, jumping over obstacles, and sprinting to a position, that provided cover and concealment (Bompa & Buzzichelli, 2015).

Despite the fact that long distance cardio training did not enhance performance, for tasks requiring anaerobic energy pathways, the guidance was to simply run more. During the times that strength training could be conducted in a gym, the emphasis was on light resistance and high repetitions. The well indoctrinated, aerobic based leaders would tell myths that heavy weight training would cause excessive mass, slow a soldier down, and get them killed. There was no knowledge of the benefits of strength and power development. The reality was that the soldiers needed strength and power development, for many of the same reasons that athletes do. Soldiers must be able to sprint, from one position to another, while under direct fire. There is a strength requirement when soldiers must physically pick up wounded comrades, and move them to safety. Negotiating obstacles, and maneuvering through difficult terrain, can require the use of all metabolic energy pathways. But yet the focus remained steadfast. Run more and do more repetitions to maximize endurance. Picking up a wounded soldier, with body armor and gear on, is anaerobic. No amount of five mile runs will assist with that task. Because of the excessive aerobic training, overtraining symptoms became common. Sarcopenia, osteopenia, and the skinny fat syndrome were present in soldiers, across the entire Army. The lack of power and strength training not only hindered performance, but caused many health issues as well (Mientka, 2013).

When power and strength training was added into the programming, along with aerobic training, performance increased dramatically. Physical fitness test scores were raised, and actual job related tasks were performed at much higher levels. By incorporating the different metabolic energy pathways into the fitness program, the limitations of the previous programming were overcome. The aerobic based leaders continued to dismiss these science based results. The modern military is finally accepting the science, and new programs addressing power and strength are being developed. Sprinting, plyometrics, and heavy resistance training are invaluable assets to any military program. Hopefully, the days of being told to just run more, are coming to an end (Stevens, 2017).

References:

Bompa, T.O., & Buzzichelli, C.A. (2015). Periodization training for sports (3rd ed.). Champaign, IL: Human Kinetics.

Mientka, M. (2013). Long-Distance Running And Endurance Exercises May Have Limited Health Benefits. Medical Daily. Retrieved from http://www.medicaldaily.com/long-distance-running-and-endurance-exercises-may-have-limited-health-benefits-246227

Stevens, E. (2017). Go anaerobic: What it is and why to do it. Breaking Muscle. Retrieved from https://breakingmuscle.com/fitness/go-anaerobic-what-it-is-and-why-to-do-it

Eric Dempsey
MS, ISSA Master Trainer

Saturday, August 19, 2017

Acute and Chronic Adaptations to Anaerobic and Aerobic Training


Anaerobic and aerobic training both result in specific, acute, and chronic adaptations. Acute adaptations to both anaerobic and aerobic training include responses, and changes, that occur during and shortly after the training. Chronic adaptations to both anaerobic and aerobic training include changes in the body that occur after numerous training sessions. These changes are longer lasting and continue on after the training sessions. While both anaerobic and aerobic training produce acute and chronic adaptations, the changes between the two types of training are very different in nature. The differences between the adaptations are largely influenced by the metabolic energy pathways used by each type of training (Coburn & Malek, 2012).

The results of anaerobic training concentrate around short duration, high power events, such as sprinting, plyometric jumps, and resistance exercises. The metabolic energy pathways used by anaerobic training include the phosphagen system and glycolysis. Acute adaptations of anaerobic training include muscular, neurological, and endocrine changes. Neurological responses include increases in motor unit recruitment and EMG amplitude. Muscular changes involve increases in hydrogen ion concentrations, ammonia levels, and inorganic phosphate concentrations. There is usually a slight decrease or no change to ATP concentrations. CP and glycogen concentrations decrease. Endocrine changes include increases in the concentrations of epinephrine, cortisol, testosterone, and growth hormone (Pike, 2015).

Chronic adaptations to anaerobic training include changes to muscle fiber characteristics, muscle enzymes, muscle substrates, and muscle performance. Structural, body composition, and neurological changes also occur. The changes to muscle fibers include increases in type I & II CSA fibers, and type IIa fibers. There are decreases in type IIx fibers and usually no change to type I fibers. Increases in muscle size, and the number of muscle fibers are also common. Structural changes include increases in bone density, bone mass, and connective tissue strength. Muscle enzyme changes include increases in the absolute levels of glycolytic enzymes, and phosphagen system enzymes. The concentrations of glycolytic enzymes, and phosphagen system enzymes may also increase. Muscle substrate changes include increases in the absolute levels of ATP, and CP. The concentrations of ATP, and CP may also increase. There are usually decreases in ATP, CP, and lactate during exercise. Muscle performance changes include increases in muscle strength, power, and endurance. Body composition changes include a decrease in body fat percentage, with an increase in fat free mass. The metabolic rate usually increases as well. Neurological changes include a decrease in cocontraction, with an increase in motor unit firing rate. There is usually an increase in EMG amplitude during maximal voluntary contraction, and motor unit recruitment. Additional changes in the endocrine, immune, and cardiorespiratory systems promote an increase in force, velocity, and power capabilities (Fitzherbet, 2012).

Aerobic endurance training causes the body to respond to stressors, through a variety of alterations and changes, in numerous physiological processes and systems. The aerobic system is suited for activities that are normally longer in duration, and less intense, than those that require the anaerobic system. Distance running, mud runs, marathons, and triathlons are some examples of activities requiring the aerobic system. Intensity, frequency and duration are key variables that impact the response of the aerobic system. Acute adaptations of aerobic training include cardiovascular, respiratory, metabolic, and endocrine changes. Cardiovascular changes include increases in heart rate, stroke volume, cardiac output, blood flow to coronary vasculature, skeletal muscle blood flow, mean arterial pressure, hematocrit, and systolic blood pressure. Other adaptations also include decreases in splanchnic blood flow, plasma volume, and total peripheral resistance. Respiratory changes include increases in pulmonary minute ventilation, breathing rate, tidal volume, and the respiratory exchange ratio. Metabolic changes include increases in oxygen consumption, blood lactate, and arteriovenous oxygen difference. There is a decrease in blood PH levels. Endocrine changes include increases in glucagon, catecholamines, and growth hormone. There is a decrease in insulin. Cortisol levels decrease during low to moderate intensity exercise, and increase during moderate to high intensity exercise (Murphy, 2015).

Chronic adaptations to aerobic training include changes to the respiratory system, blood, heart, muscle, bones, metabolism, body composition, and performance. Changes to the respiratory system include increases in respiratory muscle aerobic enzymes, and ventilatory muscle endurance. Changes to the blood include increases in blood, plasma, and red blood cell volumes. Heart changes include increases in coronary arteriole densities, and diameters, left ventricular muscle thickness, and end-diastolic chamber diameter. Sometimes there is also an increase in myocardial capillary density. Metabolism changes include an increase in lactate threshold. Muscle changes include increases in capillary density, myoglobin, mitochondria density, oxidative enzymes, triglyceride stores, and glycogen stores. Sometimes there is an increase in type I fiber cross-sectional areas. Usually, there are no changes to the muscle cross-sectional areas, type IIa, and type IIx fiber cross-sectional areas. Normally, there are no changes or an increase in bone mineral density. Body composition changes include decreases in body fat percentage, fat mass, and overall body mass. There are usually no changes to fat free mass. Performance changes include an increase in cardiorespiratory endurance. There are usually no changes in muscular strength, anaerobic power, vertical jump, and sprint speed (Lewis, 2013).

In order to isolate and enhance certain adaptations to anaerobic and aerobic training, specific exercise programs can be designed. Lactate threshold training is an example of a specific style of training that benefits aerobic performance. Conducting specific training to increase the lactate threshold causes further adaptations to the athlete’s metabolism. Raising an athlete’s lactate threshold allow the body to move further, at a higher intensity level, for longer periods of time. The increased ability of the athlete to maximize lactate clearance increases performance dramatically. A variety of exercise protocols exist where intensity and distance are manipulated during each training session. Over a period of time, these specific adaptions increase the lactate threshold and clearance capability. This ultimately improves aerobic performance (Messonnier, Emhoff, Fattor, Horning, Carlson, & Brooks, 2013).

To isolate and enhance certain, specific adaptations to anaerobic training, specialized plyometric workouts can be designed. This training maximizes the benefits of the stretch shortening cycle. By using different single and double leg plyometric exercises, in a variety of repetition and set schemes, with varying intensity levels, numerous physiological adaptations can be enhanced. This style of specific training has been shown to improve overall power, strength, stored elastic energy, stretch reflex response, motor unit recruitment, muscle fiber size, rates of force production, inhibition of antagonist muscles, activation, and cocontraction of synergistic muscles, and increased Type I and Type II muscle fiber area. By conducting plyometric training numerous, specific, anaerobic adaptations are isolated and enhanced. This improves overall anaerobic performance as well (Luebbers, Potteiger, Hulver, Hyfault, Carper, & Lockwood, 2003).

References:

Coburn, J.W., & Malek, M.H. (2012). NSCA’s essentials of personal training (2nd ed.). Champaign, IL: Human Kinetics.

Fitzherbet, H. (2012). Chronic adaptations to anaerobic and aerobic training. Prezi. Retrieved from https://prezi.com/w34-ouvi-gzx/chronic-adaptations-to-anaerobic-and-aerobic-training-phyt2001-group-presentation/

Lewis, J. (2013). The body’s response to long term exercise: The respiratory system. Prezi. Retrieved from https://prezi.com/yl0elxrsom3t/the-bodies-response-to-long-term-exercise-the-respiratory-system/

Luebbers, P., Potteiger, J., Hulver, M., Hyfault, J., Carper, M., & Lockwood, R. (2003). Effects of plyometric training and recovery on vertical jump performance and anaerobic power. The Journal of Strength and Conditioning Research. Retrieved from https://www.researchgate.net/profile/Matthew_Hulver/publication/8992729_Effects_of_Plyometric_Training_and_Recovery_on_Vertical_Jump_Performance_and_Anaerobic_Power/links/0deec520d08d225579000000/Effects-of-Plyometric-Training-and-Recovery-on-Vertical-Jump-Performance-and-Anaerobic-Power.pdf

Messonnier, L., Emhoff, C., Fattor, J., Horning, M., Carlson, T., & Brooks, G. (2013). Lactate kinetics at the lactate threshold in trained and untrained men. Journal of Applied Physiology. Retrieved from http://jap.physiology.org/content/114/11/1593.short
Murphy, P. (2015). Endurance training and adaptations of the cardiovascular system. Live Strong. Retrieved from http://www.livestrong.com/article/351971-endurance-training-and-adaptations-of-the-cardiovascular-system/

Pike, J. (2015). Anaerobic training adaptations. Live Strong. Retrieved from http://www.livestrong.com/article/442214-anaerobic-training-adaptations/

Eric Dempsey
MS, ISSA Master Trainer

Wednesday, August 9, 2017

Metabolic energy pathways provide the energy for your workouts



















The human body utilizes three metabolic energy systems to replenish adenosine triphosphate (ATP). ATP provides energy for all movements, exercises, and muscular activity. These energy systems include the phosphagen system, the glycolysis system, and the oxidative system. The phosphagen system, and the glycolysis system are anaerobic, and do not require oxygen. The glycolysis system is subdivided into two sub systems, which are fast glycolysis and slow glycolysis. The oxidative system is aerobic and requires oxygen. The three macronutrients, proteins, fats, and carbohydrates, are the main food sources for energy. Carbohydrates are the only macronutrient that can be utilized for energy, without oxygen. All physical movements and exercises require the use of one or more of the three energy systems. The type and duration of the movement, or exercise determines which energy system will be utilized (Coburn & Malek, 2012).

For short duration, high intensity, explosive, power movements, the phosphagen system is utilized. The phosphagen system is used for about the first ten seconds of activity. Examples of activities that rely on the phosphagen system include short sprints, plyometric actions such as box jumps, and powerful actions such as an Olympic lift. Even if the physical activity lasts longer than ten seconds, the phosphagen system acts first. ATP and creatine phosphate are the primary elements used by the phosphagen system. The enzymes myosin adenosine triphosphatase (ATPase) and creatine kinase play a role in the breakdown, and regeneration of ATP. The ATP is broken down to release its energy. Myosin ATPase facilitates the breakdown of the ATP into adenosine diphosphate (ADP) and phosphate. This catabolic action releases the energy from the ATP so that it can be utilized by the body. Once this occurs, the ATP must be regenerated. The adenosine diphosphate (ADP) levels rise, which activates the creatine kinase. The creatine kinase breaks down the creatine phosphate, which provides a phosphate group to combine with the ADP. This anabolic sequence produces ATP. This cycle repeats rapidly, and provides a high rate of energy, for a very short duration (Karp, 2009).

As physical exertion moves beyond the first ten seconds, the glycolysis system activates. Glycolysis breaks down carbohydrates from blood glucose, and stored glycogen to form ATP. The glycolysis system provides energy for high intensity activity, which lasts up to two minutes. For intense activities lasting for about thirty seconds, fast glycolysis is used. With fast glycolysis, pyruvate is converted to lactate, to produce ATP. The lactate can be then sent to the liver to be converted back into glucose through the Cori cycle. As the activity goes beyond thirty seconds, slow glycolysis begins to take over. With slow glycolysis, the pyruvate is sent to the mitochondria, through the Krebs cycle, to produce more ATP. This occurs from approximately thirty seconds to two minutes of intense exercise. The intensity of the activity or exercise will decline as the sequence moves through the phosphagen system, to fast glycolysis, and on to slow glycolysis. Examples of activities that could utilize the glycolysis system include a four hundred yard run, a high repetition set of a barbell exercise, or a full court press in basketball (Kelso, 2017).

At approximately the two minute mark and beyond, the oxidative system takes over from the slow glycolysis system. This is where the activity switches from anaerobic to aerobic, and oxygen is required. The oxidative system utilizes both carbohydrates and fats to fuel ATP production. Protein is not usually metabolized as fuel, unless the activity lasts for over ninety minutes. With the oxidative system, ATP production can occur through the Krebs cycle, electron transport chain, and beta oxidation. In addition to being used to produce ATP for longer, slower activities, the oxidative system also works while at rest. While at rest, fats are predominantly used as fuel. Once activity begins, it switches to carbohydrates. Once glucose levels start to become depleted, the system reverts back to fats. As the glycolysis system fades and the oxidative system takes over, the pyruvate is sent to the mitochondria, and converted into acetylCoA. The acetylCoA is then sent through the Krebs cycle for more ATP production. As glucose levels decline, fats are metabolized through the electron transport chain, and beta oxidation process, to be converted to acetylCoA. The acetylCoA then enters the Krebs cycle to produce more ATP. If the activity is very long in duration, protein can assist in energy production through gluconeogenesis and the Krebs cycle. The protein is broken down into its amino acids, which are then either converted to glucose or acetylCoA. Protein breakdown is usually minimal, as glucose and fats are normally present in sufficient quantities. for most activities. Examples of activities utilizing the oxidative system include rest, medium to long distance runs, triathlons, and manual labor during a work day (Pegg, 2013).

References:

Coburn, J.W., & Malek, M.H. (2012). NSCA’s essentials of personal training (2nd ed.). Champaign, IL: Human Kinetics.

Karp, J. (2009). The three metabolic energy systems. Idea Fit. Retrieved from http://www.ideafit.com/fitness-library/the-three-metabolic-energy-systems

Kelso, T. (2017). Understanding energy systems. Breaking Muscle. Retrieved from https://breakingmuscle.com/fitness/understanding-energy-systems-atp-pc-glycolytic-and-oxidative-oh-my

Pegg, A. (2013). What is the oxidative energy system? Steady Strength. Retrieved from http://steadystrength.com/glossary/oxidative-energy-system/

Eric Dempsey
MS, NASM Fitness Nutrition Specialist

Saturday, August 5, 2017

The sliding filament theory and muscular contraction


Muscular contraction begins with the nervous system sending a stimulus to the muscle fibers. This stimulus occurs at the neuromuscular junction. There is one neuromuscular junction for each muscle fiber. The neuromuscular junction contains structures that include the axon terminal of the neuron, the motor endplate, and the synaptic cleft, or neuromuscular cleft. From this point, the actions of the sliding filament theory begin. The actin and myosin filaments slide past each other, causing the muscle to shorten or lengthen. The filaments do not change in length during this action. Excitatory neurotransmitter acetylcholine (ACh), is released at the neuromuscular junction, after an action potential passes along the length of a neuron. ACh is released into the synaptic cleft between the axon terminal of the neuron and the muscle fiber. This occurs in direct response to the action potential (Coburn & Malek, 2012).

From that point, the Ach binds with ACh receptors, on the motor endplate of the muscle fiber. This occurs after the Ach moves across the synaptic cleft. This causes another action potential to be created. This new action potential moves along the sarcolemma of the muscle fiber. T-tubules are utilized by this action potential to travel to the interior of the muscle fiber. This movement causes the release of stored calcium from the sarcoplasmic reticulum. The calcium is released into the sarcoplasm. Once in the sarcoplasm, the calcium moves to the troponin molecules. The calcium then binds with the troponin molecules. These the troponin molecules are located along the length of the actin filaments. The shape of the troponin changes after the calcium binds to it. Tropomyosin is attached to the troponin. This change in shape causes the tropomyosin to expose the binding sites on actin, to the myosin head (Krans, 2010).

The exposed binding sites on the actin are able to attach to the myosin, forming a cross bridge. This myosin head of attachment pulls the actin filament toward the center of the sarcomere. The effort of the myosin pulling on the actin depletes the energy of the myosin. The depleted myosin must then detach from the cross bridge and reenergize itself. This requires a new adenosine triphosphate (ATP) molecule to be bound to the myosin. Once the ATP molecule is bound to the myosin, it can then detach and energize itself. The energizing of the myosin comes from the enzyme myosin adenosine triphosphatase (ATPase). The ATPase splits the ATP molecule. This energizes the myosin and allows for the cross bridge sequence to occur again. This sequence can continue as long as the muscle fiber is being stimulated to contract, by its motor neuron. The myosin pulling the actin toward the center of the sarcomere shortens the muscle. This process is the muscle contracting. The success or failure of this sequence is determined the external forces pulling against the cross bridge (Szent-Györgyi, 2004).

There are three basic types of contractions that can occur when the sliding filament theory is activated. Muscle contractions are usually pulling against an external force such as a barbell. When the myosin is pulling the actin through the cross bridge, the resistance determines the outcome. The contraction generates more force than the resistance, causing a concentric contraction. The external force is greater than the contraction force, causing a lengthening of the muscle. This is an eccentric contraction. The contraction force is equal to the resistance force, which stalls movement. This is an isometric contraction. The muscle will always attempt to shorten as the myosin pulls on the actin. The resistance level will cause one of the three types of contractions to occur. ATP is the primary fuel source for this sequence (Lefkowith, 2014).

References:

Coburn, J.W., & Malek, M.H. (2012). NSCA’s essentials of personal training (2nd ed.). Champaign, IL: Human Kinetics.

Krans, J. (2010). The sliding filament theory of muscle contraction. Nature Education. Retrieved from http://www.nature.com/scitable/topicpage/the-sliding-filament-theory-of-muscle-contraction-14567666

Lefkowith, C. (2014). What does it all mean: Concentric, eccentric and isometric. Redefining Strength. Retrieved from https://redefiningstrength.com/mean-concentric-eccentric-isometric/

Szent-Györgyi, A. (2004). The early history of the biochemistry of muscle contraction. The Journal of General Physiology. Retrieved from http://jgp.rupress.org/content/123/6/631

Eric Dempsey
MS, ISSA Master Trainer

Wednesday, August 2, 2017

Health & Fitness Radio Tuesday: Meal Planning, Vegetable Oil and More



Health and Fitness Radio Tuesday!

This episode's topics:

Meal planning, home gyms, vegetable oil, and listening to your body.

Also talked about advances in cardiac preventative care.

Eric Dempsey
MS, ISSA Master Trainer