Our Human Energy Systems

MUSINGS FROM A COACH - 3 DECEMBER '24

After chatting with a new Team MPI athlete yesterday, I thought it might be a good idea to review our human energy systems and how I use them to plan weekly training for athletes.

What better to summarize these systems than Google AI:

"Human energy systems refer to the three primary metabolic pathways the body uses to generate energy for physical activity, which are: the oxidative system (aerobic), the glycolytic system (anaerobic lactic) and the phosphagen system (ATP-PC)."

Aerobic System

Simply put, this system uses oxygen to break down fats to produce energy for the body. And we have a lot of calories stored in our body in the form of fat. Longer and easy-to-moderate efforts are typically fueled by this system.

Anaerobic System

This system uses glucose (in the blood) and glycogen (in the muscles and liver) to produce energy. We tap into this system when our effort becomes harder. The body's storage of glucose and glycogen is much smaller than the fat calories we use for the aerobic system.

Phosphagen System

This system uses creatine phosphate (CP) and has a very rapid rate of energy production. The total amount stored in muscles is small, so there is limited energy available for muscular contraction. We use this system during short-term high-intensity activities lasting about 1 to 10 seconds in duration (ramp to 30 sec), such as sprinting, weight-lifting or throwing a ball. However, it takes up to three minutes for this system to reset after use.

When I begin to flow out an athlete's weekly training plan, I first look at their time to train, then goals for that period of time and finally what energy systems I want them to target.

For example, when coaching a runner, we may be running 6 times a week along with a couple of strength sessions. For each run, I first start with what energy system I'd like to primarily target. A long run, a tempo run and a recovery run would all be primarily fueled by the aerobic system. Hill repeats and/or a track workout would target the anaerobic system. Occasionally I would target short, 30 sec repeats at max effort (with 3 minutes or recovery between each) - thus utilizing the phosphagen system. I would just make sure to strategically place each session throughout the entire week to allow for either maximum gain within each or target longer fatigue. It's not hard to then substitute a cyclist in for this example, or any single sport athlete. Where it gets tricky is working through a multi-sport athlete (like a triathlete). When an athlete is training for two or more sports in one week, the "house of cards" becomes a bit more complicated. Each system we use can be manipulated by changing the duration or even by combining them. The ultimate guiding principle, however, is deciding when and how much recovery I want in that micro cycle. As you can surmise, having an open and honest relationship between athlete and coach along with constant and consistent communication is an essential ingredient for a successful training plan. But for me, it all starts with the energy system I'm ultimately targeting for each session.

Gratefully,

Mark CEO Team MPI