Understanding Cross-Training for Trail Runners

Cross-training can be a valuable part of a trail runner’s training, helping you build aerobic fitness while reducing the impact stress that comes with running. In Ascend, cross-training is used to support your overall Cardio Fitness, allowing you to develop your aerobic engine alongside your running plan.

This article explains what counts as cross-training, how different activities are treated in Ascend, and how to get the most from your cross-training sessions.

Why Cross-Training Matters for Trail Runners

Cross-training sessions are designed to help you accumulate Cardio Fitness while limiting the impact stress associated with running. In other words, you can improve your aerobic engine without placing the same load on the muscles, joints, and connective tissues you rely on for running.

Key benefits include:

Build aerobic capacity safely. Cross-training allows you to develop your cardio engine without adding as much running-specific impact load.

Support consistency and recovery. By reducing the need to rely solely on running, cross-training can help you manage fatigue, reduce injury risk, and sustain a more consistent training routine over time.

Develop a more resilient athlete. Some cross-training activities strengthen supporting muscle groups and movement patterns that are less emphasised during running, helping create a more robust and well-rounded athlete.

What Counts as Cross-Training?

In Ascend, cross-training refers to endurance-based activities where you can maintain a relatively smooth, natural rhythm for a prolonged period at the target intensity.

Good examples include:

• Cycling, indoors or outdoors

• Elliptical

• Ski touring and cross-country skiing

• Rowing

• Swimming

  
  

These activities stress your cardiovascular system while reducing the impact load on your muscles and joints.

However, the rule of specificity still applies: the more closely an activity resembles trail running, the more directly it is likely to transfer to running performance. For example, ski touring or uphill elliptical work will usually feel more similar to running than swimming, because they involve continuous leg-driven movement in a more upright position.

That does not make swimming, rowing, or cycling any less valuable for building Cardio Fitness. It simply means they are slightly less specific to running performance.

Hiking, Hybrid Sessions, and What Counts

Hiking sits in a grey zone. Uphill hiking, whether outdoors or on a treadmill incline, can provide a strong cardiovascular stimulus with less impact than running. However, hiking still places some load on the legs, especially on steep climbs, technical terrain, or long descents.

How you log a hike matters.

If you log it as a trail run, Ascend will count it towards both your Running Impact and your Cardio Fitness. If you log it as a hike (or walk), it will contribute to your Cardio Fitness, but it will not count towards your Running Impact.

We generally recommend logging hikes as trail runs when you are moving with intent and purpose, especially if they are long, steep, or similar in effort to your usual running. This helps Ascend better account for the muscular load of the session, not just the cardiovascular benefit.

Workouts such as CrossFit, HIIT circuits, and general strength training are different. They may be valuable for building strength, mobility, and overall robustness, but they do not qualify as cross-training in this context because they do not provide the steady cardiovascular stimulus Ascend’s cross-training recommendations are designed to target.

How to Approach a Cross-Training Session

Choose an activity that allows you to settle into a consistent rhythm at the target effort. Use your Rate of Perceived Exertion as your main guide, with heart rate as a secondary reference.

Heart rate can differ slightly between activities, even when the effort feels the same. For example, cycling may produce a lower heart rate than running at a similar perceived effort because of differences in posture, muscle recruitment, and the fact that your body is supported by the bike. When in doubt, trust your perceived effort.

It is also important to adapt based on what you have access to. Ski touring may be an excellent option in winter if you live somewhere snowy, while cycling, swimming, rowing, or the elliptical may be more practical at other times of year.

If you are new to an activity, or returning to it after a long break, give yourself time to relearn the movement. At first, you may feel inefficient or struggle to sustain the intended intensity. This is normal. As your efficiency improves, it will become easier to hold the right effort and get the intended training benefit.

A Note About Cross-Training and Injury

Cross-training can be especially useful when returning from injury. It allows you to maintain or rebuild aerobic fitness while reducing impact on healing tissues.

However, more is not always better. Cross-training still adds training load, and doing too much can slow recovery or create fatigue elsewhere. Use it as a supplement to support your return to running, not as a replacement for the rest your body may still need.

In summary

Cross-training helps you build Cardio Fitness, reduce impact stress, and maintain consistency as a trail runner. The best activities are those you enjoy and can sustain over time, while still providing a steady cardiovascular stimulus that allows you to recover well and continue progressing with your running.

When logging completed activities, remember the key distinction: cross-training workouts count towards your Cardio Fitness, helping build your aerobic engine, while activities logged as runs contribute to your Running Impact as well as your Cardio Fitness. Activities logged as hikes or walks count towards Cardio Fitness but not Running Impact.

To learn more about how your training plan is generated, including how Ascend schedules cross-training alongside your running, check out our guide to planning your training week.