August 20, 2025 · Improving Performance

rest between sets

Have you ever wondered why your coach sometimes asks you to rest for 3–5 minutes between heavy strength sets, but gives you almost no rest during a MetCon? It all comes down to the energy system being trained.

During heavy lifts, the body relies on explosive but short-lived energy, which needs longer recovery before you can perform again. In contrast, MetCon sessions train your aerobic system, which can sustain effort for much longer but at lower intensity.

Let’s break down the three main energy systems we train with, without getting too “Year 12 PE” about it.

1. ATP-PC System (Phosphate System)

  • The sprinter’s system. Think of a 100m dash.
  • Most explosive, but very limited, lasts only 8–10 seconds.
  • Needs 3–5 minutes of complete rest to recover properly.
  • Best for single heavy lifts or short bursts of max effort.

2. Anaerobic Glycolysis

  • The middle ground. Think of a 200m sprint.
  • Lasts around 30–45 seconds of intense effort.
  • Fuels activities like hard 20-second bursts on the air bike.
  • Recoverable with 2–3 minutes of rest, which is why HIIT sessions feel how they do!

3. Aerobic System

  • The workhorse. Think marathon running.
  • Kicks in after about 60 seconds of continuous work.
  • Relies on oxygen, making it less powerful but highly sustainable.
  • Can run for hours when fuelled properly, food about 30–60 minutes before training helps.
  • Rest depends on focus:
    • Longevity sessions: often minimal rest.
    • Power sessions: short rests, similar to anaerobic training.
  • This system is also one of the most effective for calorie burn and weight management.

Why Does Rest Matter?

  • ATP-PC and Anaerobic Glycolysis don’t rely on oxygen, so the best recovery is passive rest, literally sitting down. Take this time to catch your breath (and maybe chat with your coach).
  • All systems recover better with the basics: good nutrition and sleep.

So, the next time you’re asked to sit for 5 minutes between heavy lifts or grind through a MetCon with no breaks, you’ll know exactly why.

But don’t let your rest time be purely passive. This is where I love to get my mobility work in. If I’m benching a pec stretch can assist my performance. If I’m squating, ankle and hip mobility and quad stretches can aid my lifts and be a great way to get more work into each minute of my strength classes.
 
MetCon breaks, keep them passive. You know you need it!

Want to learn how to tailor your training to your goals?
👉 Click here to book a consultation with a RevoPT university-accredited coach and get a program designed just for you.

Liam