Course:KIN366/ConceptLibrary/Anaerobic Fitness

Movement Experiences for Children
KIN 366
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Instructor:	Dr. Shannon S.D. Bredin
Email:	shannon.bredin@ubc.ca
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Anaerobic Fitness

Anaerobic Fitness

Definition

Anaerobic fitness is a form of physical activity and subsequent energy metabolism that does not rely on the presence of oxygen within the living tissue in order to carry out necessary fuel exchanges.The muscles rely solely on stored ATP, phosphocreatine, and/or glycogen stores present within the muscle’s energy stores in order to carry out activity. Which energy source is utilized depends on the duration and intensity of the exercise. Short, high-intensity exercises which promote strength, speed, power, and the building of muscle mass are prototypical anaerobic exercises that improve one’s anaerobic fitness levels. Within the anaerobic system there are two main energy pathways; the Adenosine Triphosphate – Creatine Phosphate System (also known as the Phosphate, ATP-CP, ATP-CPr, ATP-PC, ATP-PCr, Phosphocreatine, PCr, or Phosphogen Systems) and the Anaerobic Glycolytic System (also known as the Anaerobic Lactic Acid system). Between these two anaerobic energy pathways, anaerobic exercise generally lasts between 10 seconds up to 60 seconds before oxygen is required in order to synthesize energy to sustain the physical activity taking place. These activities generally take place at around 50-80% of one’s VO2 max.

Anaerobic Energy Pathways

Adenosine Triphosphate – Creatine Phosphate System (ATP-CP)

The ATP-CP system relies solely on stored Adenosine Triphosphate (ATP) within the muscles in order to fuel short burst, high intensity exercise. The stored ATP lasts approximately 2-3 seconds at which point the stored creatine phosphate (CP) is utilized to resynthesize ATP. The CP is broken down by the enzyme creatine kinase into a free creatine molecule and Adenosine Diphosphate, subsequently releasing a phosphate and an energy molecule used to resynthesize ATP. The CP stores last approximately 6-8 seconds, which makes the ATP-CP system ideal for quick burst, powerful movements lasting up to approximately 10-15 seconds. The ATP-CP system requires roughly 2-3 minutes in order to replenish it’s ATP and CP stores before maximal intensity, short bout exercise can commence again at full efficiency.

Anaerobic Glycolytic System

Once the ATP and CP stores have been depleted the Anaerobic Glycolytic System takes over energy metabolism. This system relies on glycolysis: the breakdown of glucose into two pyruvic acid molecules and 2 ATP without the presence of oxygen. Glucose is often stored as glycogen within the muscles and liver. Due to the lack of oxygen present, the majority of the pyruvic acid is converted into lactic acid which eventually diffuses back into the blood stream, sent to the liver and converted back into glucose. This utilization of lactic acid as a fuel source debunks the theory that lactic acid is strictly a by-product, but rather a fuel source during rest and activity.

Forms of Anaerobic Training

Training the ATP-CP Energy Pathway

Depending on the individual’s athletic pursuits, anaerobic training comes in a variety of different forms. Depending on the athlete’s physical capabilities and limitations, any activity that has a duration less than roughly one minute will rely primarily on the anaerobic energy pathways. The shortest duration examples being power lifters and plyometric exercises which require short burst power movements which do not last any longer than 2-3 seconds in duration. This short burst, high intensity, power type movement relies almost solely on the ATP-CP energy system. As stated earlier, the ATP-CP system can fuel movements for up to 10-15 seconds, however, it requires the breakdown of creatine-phosphate in order to supply energy for the working muscles.

Training the Anaerobic Glycolytic Energy Pathway

Once high intensity exercise begins to surpass this 10-15 second marker and build up to durations under roughly 60 seconds, the Anaerobic Glycolytic energy system takes over. Examples of exercises which would persist for such a duration of time might be high intensity interval training (HIIT), a weight lifting circuit which has a higher rep count and tempo than that of a power lifter, be it a strength or hypertrophy program. HIIT is any form of exercise that is performed at 90-100% of one’s maximal heart rate for a duration of 10-15 seconds. The rest interval required in order to replenish the ATP-CP stores is roughly 30-60seconds as recovery should be three times that of the work interval. One can also train the Anaerobic Glycolytic System by increasing the work interval to within 10-60seconds, with the same intensity, however, keep in mind that the rest interval must also be lengthened to roughly 3-5 minutes. Despite common misconceptions, when one energy system is being utilized, that does not mean the other energy systems have shut down completely. All of the energy systems are operating simultaneously at any given time, however, dependent on the activities being performed by the individual, one energy system might be functioning at a higher level than the rest. Given this, all energy systems are operating concurrently, however, certain activities are predominated by specific energy systems.

Advantages of Anaerobic Training

Anaerobic fitness has a variety of different physical benefits that occur with prolonged training regimens. For example, HIIT increases the resting levels of ATP-CP in resting muscles as well as the neuromuscular firing rate and motor unit recruitment patterns in order to specialize the muscle units to the desired movement. With prolonged anaerobic training, one will begin to experience physiological adaptations such as an increased lactate tolerance, hypertrophy of fast-twitch type IIa and type IIb muscle fibers and increased resting level of ATP, creatine phosphate, creatine, and glycogen within the muscles. These physiological adaptations allow the athlete to perform exercises at a higher intensity over specified distances and/or over longer durations of time.

Physiological Adaptations

Increased Lactate Threshold (LT)/Onset Blood Lactate Accumulation (OBLA )

Lactate Threshold (LT) occurs when the accumulation of lactate within the bloodstream due to the breakdown of glycogen via the Anaerobic Glycolytic energy pathway occurs at a faster rate than the lactate can be removed and resynthesized into glucose. LT or Anaerobic Threshold (AT) is commonly referred to as “the burn” one experiences after prolonged high volume, maximal steady-state and/or intense interval exercise. Despite the common belief that the accumulation of lactate is what causes such said discomfort, it is the acidosis and hypoxic environment created within the muscle body due to the accretion of hydrogen ions that coincide with the lactate build-up. This acidic environment impairs the muscle’s ability to contract with maximal efficiency and strength. The accumulation of lactate is a result of the constant splitting of ATP by the anaerobic glycolytic system to provide free energy for the vigorous muscle contractions. The lactate by-product that is produced is removed via uptake by the heart, liver, and kidneys as metabolic fuel for glucose production via gluconeogenesis.

The soreness experienced post-exercise has also historically been attested to lactic acid accumulation and lack of recovery post-exercise. However, this too is a common misconception that is due to minor strains within the muscle tissue and the contractile elements due to overuse. This localized “microtrauma” causes increased blood flow to the area resulting in swelling and increased pressure on the pain receptors. The nerve supplies of the area perceive this increased pressure as muscle damage, ultimately resulting in this muscle soreness experienced after many anaerobic training sessions. In order to return the muscle to a normal state, one must begin to move the musculature as normally as possible and stretch the muscle bodies. The use of myofascial release therapy, sports balms/creams, hot tub/saunas, aspirin, and anti inflammatories can assist in subsiding the painful sensation.

Anaerobic Fitness and Children

Like most forms of physical activity, anaerobic fitness and muscular strength is an important component in a child’s development. There has been controversy on this topic, specifically with regards to children and strength training. It is imperative that whoever is administrating the strength training program is certified, has a wealth of knowledge on the exercises being performed and that safety is the number one priority. Studies have shown that performing resistance training in children and adolescents for 10-60 minutes, 2-3 times/week with a rest day in-between sessions improves muscular strength by 20-30%. These strength gains however cannot be attested to muscular hypertrophy due to the lack of androgens in the pre-pubescent individual. These strength gains can be attributed to improved motor skill coordination, motor unit recruitment and activation, and neurological adaptations. One of the main concerns with strength training in pre-pubescent children is the effect it will have on their growth, however, studies show that after performing a strength training program there is no damage to the epiphyses or bones. Rather there are actually benefits to the skeletal tissue due to the compressive and tensile forces on the bones from muscular contractions during weight-bearing activities. Bone mineral density, bone mineral apparent density, and bone mineral content all improve.

It has been proven that there is no harm in individuals performing strength training from a young age. Given the nature of much of a child’s play activities, they too are generally anaerobically based e.g. tag. It is important that one tries to combine the anaerobic and strength training with the development of fundamental motor skills. An example would be to perform ten, ten second intervals of an anaerobic fundamental movement pattern such as jumping, hopping, skipping etc. These activities can also be resisted, however, it is imperative to never perform maximal activities, to always work through the full range of motion and emphasize safety and proper technique while under supervision. Despite children’s lower levels of anaerobic and aerobic fitness capacities, they do have faster recovery times than adults allowing for shorter than usual rest periods. Below is a basic guideline to resistance training for children by Matt Kathol:

BASIC GUIDELINES FOR RESISTANCE EXERCISE PROGRESSION IN CHILDREN AGE CONSIDERATIONS

7 or younger Introduce basic exercises with little or no weight: teach exercise techniques. Develop the concept of a training session. Progress from body weight calisthenics, partner exercises, and lightly resisted exercise. Keep volume low.

8-10 Gradually increase the number of exercises and training volume. Practice exercise technique in all lifts: keep exercises simple. Start gradual, progressive loading of exercises, carefully monitoring toleration to the exercise stress.

11-13 Teach all basic exercises and training volume. Continue progressive loading of each exercise. Introduce more advanced exercises with little or no resistance.

14-15 Progress to more advanced youth programs in resistance exercise. Add sport-specific components. Emphasize exercise techniques. Increase volume.

16 or older Move child to entry-level adult programs after all background knowledge has been mastered and a basic level of training experience has been gained.