The Basics: Cardio Load

Cardio Load at a glance

Cardio Load measures the balance between your short-term (acute) and long-term (chronic) training load—also known as ATL and CTL. In essence, it provides a metric that indicates whether your body is being appropriately challenged, overworked, or undertrained.

This metric helps guide your body's adaptive response—the process of becoming stronger, fitter, and more resilient. When managed well, Cardio Load keeps you in the sweet spot: training hard enough to stimulate progress, but not so hard that it leads to fatigue or burnout.

Why Cardio Load matters

Cardio Load is a powerful tool for avoiding two major setbacks in training: overtraining and detraining. Overtraining happens when your body doesn’t get enough time to recover, leading to fatigue, performance drops, and potential injury. Detraining occurs when your workouts don’t provide enough stimulus to drive improvement.

By regularly monitoring your Cardio Load, you gain insights into how well your training aligns with your body's capacity to adapt. This empowers you to make informed adjustments, so each session supports your performance goals while minimizing risk.

What influences Cardio Load?

Cardio Load is shaped by both your short-term load (the past 7 days) and long-term load (the past 6 weeks). Bevel calculates this using TRIMP (Training Impulse), a method that quantifies training stress based on key physiological factors:

• Heart Rate: A core indicator of effort, heart rate reflects how hard your cardiovascular system is working. As exercise intensity increases, so does your heart rate, making it a reliable measure of internal load.
• Exercise Duration: The length of a workout plays a major role in total stress. Longer sessions generally contribute more to your Cardio Load, impacting both your cardiovascular and muscular systems.

Interpreting the chart

The Cardio Load chart helps you visualize how your body is responding to training. You will see a Short-term Load value, and Optimal Load Range. Here’s how to interpret them:

• Short-term Load: The line and markers represent your current and historical short-term load (ATL). A higher ATL represents increasing load over the past 7 days, while a lower ATL represents decreasing load.
• Optimal Load Range: Represents the ideal range for your short-term load (ATL) to stay balanced with your long-term load (CTL). The lighter color on either side of the range represents a margin of safety for your optimal ATL:CTL ratio.

• Cardio Status: Represents how your cardiovascular system is responding to your recent training, offering insights into your current training trajectory and recovery state. We have the following six statuses:
  • ‍Detraining: Losing progress, scale up your cardio training.‍
  • Maintaining: Training is steady and balanced.‍
  • Productive: Making strong cardio gains. ‍
  • Peaking: Peak condition, well recovered. Ideal race condition.‍
  • Fatigued: Pushing but not recovering well.‍
  • Overtraining: At risk of injury, scale back your cardio training.

To learn more about the different Cardio Statuses and what they mean for you, continue reading Cardio Status.

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How to use Cardio Load effectively

Make Strategic Adjustments: Monitor your Cardio Load regularly to spot trends. If you're trending toward overtraining or detraining, tweak your workout intensity, duration, or frequency to bring your load back into an optimal range.

Balance Work and Recovery: Staying within your ideal Cardio Load range helps you challenge your body while allowing enough time for recovery. This balance supports consistent performance gains and minimizes the risk of fatigue, injury, or burnout.

By actively managing your Cardio Load, you’re better equipped to train smarter, not just harder. It’s a powerful tool to help you push your limits while respecting your body’s need for rest and adaptation.