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It's Tough, But It'll Build A Monster Aerobic System

https://www.youtube.com/watch?v=HuY7wmJC7eM

TLDR Build a strong aerobic system by combining long easy sessions, threshold work, VO₂ max intervals, and short sprints. A simple plan is two quality days and one long day each week, rotating workouts over a two-week block; increase training gradually and eat enough to support recovery.

Key Insights

Train the Whole Aerobic System

Build fitness by developing more than just heart-pumping power. The heart, blood, blood vessels, and muscles all contribute to endurance, and different workouts support different parts of that system. Intervals can strengthen high-intensity capacity, while easy training builds the foundation that helps you sustain effort. Relying on only one type of training can eventually limit progress.

Include Four Training Intensities

Use a mix of long, easy efforts lasting at least 60 minutes, threshold or tempo intervals, hard VO₂ max intervals, and short all-out sprints. Example sessions include 5 × 6 minutes at threshold, 4 × 4 minutes at VO₂ max effort, or 10–20-second sprints. Each intensity serves a different purpose, so avoid trying to make every workout hard. Aim to train each system at least once every 10–14 days.

Organize Training Around Two Quality Days and One Long Day

A practical weekly structure is two challenging workouts, one long easy session, and easy training on the remaining days. Rotate the quality sessions across a two-week block—for example, threshold and VO₂ max intervals in the first week, then threshold and sprint work in the second. This gives each energy system attention without making every week overwhelming. On some easy days, add four or five short accelerations of 10–20 seconds to maintain speed with little recovery cost.

Increase Training Gradually

Progress by slowly adding training volume or intensity until a previously challenging workload feels manageable. Avoid sudden jumps, which can leave you fatigued or cause you to miss sessions. Consistent, sustainable training is more useful than short bursts of excessive effort. Think in terms of building your aerobic system over months and years.

Fuel Training and Recovery

Eat enough to support your workouts and recovery. Trying to build fitness while restricting calories or actively losing weight can contribute to relative energy deficiency in sport (RED-S). Prioritize establishing a strong aerobic base first, and consider fat loss afterward if it remains a goal. Adequate fueling helps you train consistently and recover between sessions.

Questions & Answers

What is the main principle for building a strong aerobic system?

Train the whole system rather than relying on one popular method. Intervals strengthen the heart’s pumping ability, while easy training develops other parts of the system, including blood vessels and muscles.

What four training intensities does Nicholas recommend?

Long easy efforts of 60 minutes or more; comfortably hard threshold or tempo intervals, such as 5 × 6 minutes or 3 × 10 minutes; hard VO₂ max intervals, such as 4 × 4 minutes; and all-out sprints lasting 10–20 seconds.

How often should each energy system be trained?

Aim to train each system at least once every 10–14 days. Workouts do not have to fit into a strict seven-day schedule.

What is a simple weekly training structure?

Do two quality sessions and one long session each week, with the remaining sessions easy. Rotate the quality workouts across a two-week block—for example, threshold and VO₂ max one week, then threshold and sprints the next.

How can athletes maintain speed on easy days?

Add four or five short accelerations of 10–20 seconds to some easy sessions. These help keep fast-twitch fibers and speed active with little recovery cost.

How should training be increased over time?

Gradually increase training volume or intensity until challenging work becomes the new normal. Avoid sudden increases that cause excessive fatigue or missed sessions, and build the aerobic system over years.

Why is adequate fueling important, and when should athletes pursue fat loss?

Eating enough supports training and recovery. Restricting calories or losing weight while trying to build fitness can contribute to relative energy deficiency in sport (RED-S). Nicholas recommends building the aerobic base first and pursuing fat loss afterward if desired.

Summary of Timestamps

Nicholas, a former professional triathlete with degrees in sports science and physiotherapy, explains that developing a strong aerobic system means training the whole system—not relying on a single popular workout. He uses a garden analogy: the heart is a pump, blood is water, blood vessels are hoses, and muscles are plants. Intervals can strengthen the pump, while easy training supports the rest of the system; neglecting either can eventually limit progress.

He recommends training across four intensity levels: long, easy efforts of 60 minutes or more; comfortably hard threshold or tempo intervals, such as 5 × 6 minutes or 3 × 10 minutes; hard VO₂ max intervals, such as 4 × 4 minutes; and all-out sprints lasting 10–20 seconds. The goal is to train every energy system regularly, not necessarily to fit every workout into each seven-day week.

Rather than forcing a rigid weekly schedule, aim to train each system at least once every 10–14 days. This flexible approach can help athletes balance different types of training without making any one week too demanding.

Progress comes from gradually increasing training volume or intensity until a challenging workload becomes the new normal. Increase training carefully: a sudden jump can cause fatigue, disrupt recovery, or lead to missed sessions, undermining consistency.

Fueling is also essential. Trying to build fitness while restricting calories or losing weight may contribute to relative energy deficiency in sport (RED-S), which can impair health and performance. Nicholas recommends building the aerobic base first and pursuing fat loss afterward, if desired.

A practical structure is two quality training days and one long day each week, with the remaining sessions kept easy. Rotate the quality workouts over a two-week block—for example, threshold and VO₂ max work in the first week, then threshold and sprint work in the second—so all four intensities are covered without overloading a single week.

On additional easy days, athletes can include four or five short accelerations lasting 10–20 seconds. These brief efforts help keep speed and fast-twitch fibers active while adding relatively little recovery cost. Overall, the advice is to build aerobic fitness gradually over years, increase training progressively, and eat enough to support recovery.