Understand your Endurance Fitness (Chronic Load)
Endurance Fitness, also known as Chronic Training Load (CTL), provides a long-term view of your training adaptation. Located on the Progress tab, this metric helps you understand how much structured work your body is used to, reflecting the durability of your endurance base. Use it to track your fitness development and ensure you are building your base consistently over time.
Analyzing Your Endurance Fitness
On the main Progress tab, the Endurance Fitness card provides a quick summary of your current status.
This card displays:
- Chronic Load: Your current numerical score, representing your fitness base over the last 42 days.
- Fitness Level: A rating of your current Chronic Load, such as VERY GOOD, GOOD, or FAIR.
- Trend Graph: A small line chart showing your Chronic Load fluctuations over the recent past.
Tapping on this card will take you to a more detailed analysis screen.
Detailed Endurance Fitness View
The detailed view offers a deeper dive into your long-term fitness trends.
- Main Chart: A line graph visualizes your Chronic Load over a selected period, typically 4W (4 weeks) or 6M (6 months). This helps you see how your fitness base has evolved.
- 4-Week Overview: This section summarizes your key stats for the selected period, including your Average, Max, and Min Chronic Load.
- Endurance Fitness Breakdown: This part shows the percentage of time you have spent in each fitness level (e.g., Low, Fair, Good, Very Good).
Understanding the "Learn More" Section
At the bottom of the detailed view, you can tap on two cards to get more context about the metric.
- Chronic Training Load: This card explains the concept in detail. CTL tracks your long-term training adaptation by reflecting the structured work your body has handled, typically calculated over the past 42 days using an Exponentially Weighted Moving Average (EWMA). A higher number indicates a more durable endurance base, while a drop often signifies deconditioning.
- Chronic Training Load Levels: This card provides a breakdown of the different CTL levels and what they mean, from Low (below 25 CTL) to Very High (150 CTL and above). Each level corresponds to a typical training volume and athletic status, helping you compare your fitness to established benchmarks.
Tips for Interpretation
A steady, gradual increase in your Chronic Load is ideal for building fitness while minimizing injury risk. Pay attention to sharp spikes, which could indicate overreaching, or significant drops, which may mean you are losing fitness due to inconsistency.
Summary
The Endurance Fitness (Chronic Load) feature is a powerful tool for monitoring your long-term fitness progression. It helps you track the development of your aerobic base, understand your body's adaptation to training, and manage your workout volume to support steady, sustainable progress. By analyzing your trends and understanding the different fitness levels, you can make more informed decisions about your training.
