Energy Systems and Metabolism

• Exercise physiology studies the body's functional and structural responses at the cell, tissue, organ, and system levels to acute exercise stress and chronic physical activity.
• Exercise physiology is the study of the body's responses to physical activity, including changes in metabolism, and structural changes in cells.
• Exercise physiology includes both sport exercise physiology related to athletes and clinical exercise physiology

Clinical Exercise Physiology

• Clinical exercise physiology involves applying exercise physiology's principles, knowledge, and skills, for the prevention, rehabilitation, or diagnosis of disease or disability in humans considering physiological systems such as cardiovascular, respiratory, nervous, renal, GI, temperature regulation, endocrine, muscle, bone, skin, and immune.

Responses vs Adaptations

Responses are temporary changes in the body's function due to exercise, while adaptations are lasting structural or functional changes that occur over time.

• Responses are sudden, temporary changes in the body's function caused by exercise, disappearing shortly after.
• Adaptations are persistent structural or functional changes following training, not seen until several weeks of training.
• Adaptations occurring immediately before, during, or after exercise are acute responses, while gradual responses lasting as long as you maintain your exercise program are chronic adaptations.
• A response is a short-term change caused by a stimulus, where as, adaption is a long term change caused by a stimulus

Training and Conditioning

• Training is regularly practicing an activity, which leads to conditioning.
• Training is a systematic, long-term, and progressive process that recognizes the individual needs and capabilities, its objective to improving fitness
• Training programmers use exercise or practice to develop the qualities required for an event.
• Conditioning is the physical effect of training, for example, improved flexibility, strength, and endurance.
• There are three types of muscle skeletal: Striated, smooth, and cardiac

Energy Sources

• During rest, muscles primary source of energy is fatty acids; during activity, muscles primary source of energy is carbohydrates (glucose).
• Adenosine Triphosphate (ATP) is the source of energy for use and storage at the cellular level, its structure consisting of a nitrogenous base (adenine), a ribose sugar, and three serially bonded phosphate groups.
• Every bond of ATP results in about 12,000 calories when broken down.
• The structure of ATP has a high energy bonds between Adenine, Ribose, and Phosphate

The Three Major Energy Systems

• Three major energy systems replenish ATP: Ultra Paired Creatine Phosphate, Anaerobic Glycolysis, and Oxidative Phosphorylation, each has their associated advantages and disadvantages
• All energy systems are active, however on sport or exercise will become the predominate energy system used

• Creatine Phosphate (CrP), also known as phosphocreatine, is a high-energy molecule stored in muscles and serves as a critical energy reserve for rapid ATP regeneration during short bursts of intense physical activity. It plays a vital role in the ATP-PCr energy system, which allows for immediate replenishment of ATP, especially during anaerobic activities like sprinting or lifting heavy weights. When the demand for energy exceeds the capacity of aerobic processes, CrP donates a phosphate group to adenosine diphosphate (ADP) to reform ATP, allowing continued muscle contraction. The availability of creatine phosphate can significantly enhance athletic performance and is utilized in various sports and exercise regimens to improve strength and power output.

• Creatine phosphate is a high-energy phosphate stored in muscle that releases energy when its phosphate bond is broken.

• Creatine phosphate is Catalyzed by Creatine Kinase (CK) and increases when ADP increases

• The energy released from creatine phosphate is used to rephosphorylate ADP into ATP serving as readily accessible reservoir of energy for re-formation of ATP

• A single molecule of CrP can rephosphorylate one molecule of ADP to ATP (1:1 ratio) and 5-10 seconds of CrP in muscle to be depleted

Anaerobic glycolysis is a metabolic process that occurs in the absence of oxygen, allowing cells to produce energy rapidly when oxygen supply is limited. This pathway primarily breaks down glucose, which can be derived from glycogen stores, into pyruvate. The process generates a net gain of 2 ATP molecules per glucose molecule, providing quick bursts of energy during high-intensity activities such as sprinting or weightlifting. The pyruvate produced is then converted into lactate, which may contribute to muscle fatigue if accumulated in large amounts. Overall, anaerobic glycolysis is essential for activities that require immediate energy output, supporting muscle contraction during strenuous exercise.

• Anaerobic Glycolysis starts with glucose and ends with lactate.
• In the first reaction, ATP is added to glucose to form glucose-6-phosphate (G-6-P).
• In the 6th reaction, ADP is rephosphorylated to ATP and this step is repeated, producing 2 ATP.
• The 9th reaction produces 2 additional ATP and pyruvate, which then proceeds to lactate.
• Glycolysis produces 4 ATP, but 2 ATP are used in the process, so net production is 2 ATP.
• Advantage: Uses blood glucose and stored glycogen, so use is rarely limited by depleted energy stores.
• Disadvantage: Acidity increases, or decline in pH within the muscle cell that occurs when anaerobic glycolysis is used at a high rate.
• Metabolic acidosis can decrease activity of key metabolic enzymes, interfere with force production and cause muscle fatigue and this occurs in 1-2 minutes.

Oxidative Phosphorylation

• Also known as crep's cycle
• Glucose breakdown with the presence of O2
• Pyruvic acid enter in the mitochondria and then transfer into acetyl co A then also break down by many enzymes produced a large amount of ATP
• Used in longer durations of as done by endurance athletes
• Advantages: Supplies ATP on a virtually limitless basis as long as oxygen and fuel sources are available
• Disadvantages: The reactions are ver slow dependent upon the oxygen supply

Oxygen Debt

• At the end of physical activity, the demand for ATP decreases, but the amount of oxygen required still remains above the amount required at resting levels.
• Oxygen Debt is the volume of oxygen used during recovery from exercise in excess of resting oxygen consumption
• The increased oxygen consumption can last for a period of minutes or hours after physical activity and is necessary for recovering from exercise
• The size of the oxygen debt is proportional to the intensity and duration of the activity undertaken.
• Respiration rate and HR will remain elevated to enable higher oxygen consumption

Muscle Fibres

There are three types:

• Type I: Slow contraction speed, uses O2 as a primary ATP source, slow rate of fatigue, high # of mitochondria and capillary density, low glycogen capacity and force production, small fiber diameter and motor neuron size, high oxidative capacity, and used for long-duration activities.
• Type IIa: Fast contraction speed, uses Glycogen Glucose-LA as a primary ATP source, intermediate rate of fatigue, # of mitochondria and capillary density, intermediate glycogen capacity and force production, large fiber diameter and motor neuron size, intermediate oxidative capacity, and used for short duration activities.
• Type IIb: Fastest contraction speed, uses Phosphocreatine as a primary ATP source, fast rate of fatigue, low # of mitochondria and capillary density, high glycogen capacity, large fiber diameter and smallest of motor neuron size, highest force high oxidative capacity, and used for short - medium duration activities.

Myoglobin

• The differences between muscle fiber types is dependant on which muscles relies on oxygen in the production of energy
• Myoglobin protein that delivers oxygen to working muscles
• This allows energy-producing biochemical reactions to be sustained over a long period of time using aerobic processes for energy production to sustain activity longer

Types Of Contractions

• Isotonic: Consisting of dynamic movements while under a constant load
  • Concentric contraction: upward movement is under tension and the muscle shortens
  • Eccentric contraction: Downward movement controls tension while the muscle lengthens
• Isometric- Involves muscle contraction that is static with no change in muscle length

Explore the body's energy systems, including glycolysis, oxidative phosphorylation, and the role of creatine phosphate. Understand ATP production, oxygen debt, and the factors limiting energy supply during physical activity. Learn about metabolic processes during exercise.