Metabolism - Sports Nutrition (EXPH 191) - Fall 25

The sum of all chemical reactions in a cell or the human body

Metabolism

There are over how many known metabolic reactions

4000

Is metabolism static or dynamic?

Dynamic (body is constantly breaking down and rebuilding molecules)

Metabolism is the process through which humans acquire and use what?

ATP

Constructs smaller molecular substrates into new and bigger products.

Anabolic Reactions (Anabolism)

Process of anabolic reactions

Synthesis

3 Examples of Anabolic Reactions

Muscle rebuilding and recovery, protein creation, and hormone synthesis

Destroys products into smaller molecular substrates.

Catabolic Reactions (Catabolism)

Process of catabolism

Breakdown

Energy state differences between anabolic and catabolic reactions

Anabolic uses useful forms of energy, Catabolic produces useful forms of energy

Substances that help prevent the breakdown of muscle tissue, often associated with anabolic processes

Anti-catabolic food molecules

3 Components of ATP

Adenine, ribose, and three phosphate groups

Since ATP is not stored in large amounts, the body must store food particles as backup reserves for its continuous creation, with the two main storage forms being

Carbs and fats

ATP stores never become completely depleted, even during intense or prolonged exercise, because why?

It is resynthesized at the same rate at which it is depleted

The body primarily uses which macronutrient first in ATP generation?

Carbs, then fat

Even at rest, each muscle cell contains approximately how many ATP molecules?

1 billion

When stimulated, ATP molecules will be used and replaced in what period of time?

2 minutes

Complex carbohydrates break down into what?

Glucose

Carbohydrates are stored as glycogen in what two tissues of the body?

Liver and skeletal muscle.

Fats break down into what?

Triglycerides

Fats are stored in what tissue?

Adipose

3 Adipose Tissues fat can be stored in

Visceral adipose tissue, subcutaneous, and intramuscular adipose tissue

Adipose tissue in and around the organs

Visceral adipose tissue

Adipose tissue that we store just under the skin

Subcutaneous adipose tissue

Lining of fat that we get inside the muscle

Intramuscular adipose tissue

Proteins break down into what?

Amino acids

Fundamental reaction of ATP

Pi + ADP —> ATP

Goal of aerobic and anaerobic metabolism

Produce ATP

Anaerobic metabolism uses or doesn’t use oxygen?

No O2

2 Anaerobic reactions

Phosphagen System (ATP-PCr system) and Glycolysis

Vertical jumps, your sprints, your long jumps, your one RM are examples of which anaerobic system?

Phosphagen system

Speed type of events that are up to around two minutes; 400 yard dash, repeated sprints, basketball, hockey, anything that's up and down the field are examples of which type of anaerobic reaction?

Glycolysis

Aerobic metabolism uses or doesn’t use oxygen?

Uses O2

2 Aerobic Reactions

Krebs cycle and Electron transport chain

Term used for combination of Krebs cycle and ETC processes

Oxidative phosphorylation

Steady state, long duration types of activities; long runs, bicycling, triathlons, marathons, anything that goes over 2 minutes are examples of which type of metabolism?

Aerobic

Under resting conditions, energy systems operate continuously or not in most tissues?

Continuously

All three energy systems are always on, they are always working, but what will determine which energy system is primarily providing ATP.

The type of activity being done

Energy system for immediate ATP regeneration during maximal exercise.

Phosphagen system (ATP-PCr system)

During maximal exercise, the muscle's existing ATP is only sufficient to fuel approximately how many seconds of muscle force-generating activity.

2

ATP-PCr system purpose

Fast resynthesis of ATP to prevent complete depletion

ATP-PCr system provides energy during what type of exercise.

High-intensity, short-duration

ATP-PCr system occurs where?

Cytoplasm

Phosphagen system reaction?

ADP + PCr —> Cr + ATP

ATP-PCr system reaction involves the transfer of what?

One phosphate group

How is the one phosphate group in ATP-PCr system is transferred? 

The phosphate from phosphocreatine (PCr) is transferred to ADP, creating ATP

The enzyme that facilitates and stimulates ATP-PCr reaction

Creatine kinase

Role of creatine kinase

Depletes PCr to maintain ATP (via phosphate group transfer)

PCr is stored where in the body?

Muscle fibers

Inside the muscle fiber, phosphocreatine stores are typically how many times greater than ATP stores?

3 to 4

While highly effective at rapid ATP production, the phosphagen system has a very low what?

Capacity

During intense exercise, phosphocreatine levels fall very rapidly and can be near-depleted within how many seconds.

10 to 20

2 Storage Areas of Creatine

Muscle (95-98%) and in the testes and brain (2% to 5%)

Purpose of Creatine Supplementation

Increase muscle PCr stores and power and capacity of phosphagen system

Having more PCr in muscle allowing for what?

Greater ability to regenerate ATP rapidly

Complete resynthesis of PCr after very high intensity exercise normally takes how many mins?

3-5

As the phosphagen system's capacity declines, which energy system ramps up for a more significant role in ATP production

Glycolysis

Glycolysis starts at onset of contraction but doesn’t reach maximal rate until after how many sec

5

Refers to the metabolism of glucose, literally meaning "the splitting of glucose."

Glycolysis

What does glycolysis start and end with

Starts with glucose, ends with pyruavte

Net production of glycolysis

2 ATP (-2 in phase 1 and 4 produced in phase 2)

Location of glycolysis

Cytoplasm