148. SAME HOURS, DIFFERENT LOAD: WHY VOLUME DIFFERS BETWEEN CYCLING AND RUNNING
You’ve probably come across the idea that high training volume is pivotal to optimize endurance performance —and rightly so. Both scientific evidence and collective field experience consistently show that accumulating a large volume of training is one of the key drivers of endurance performance over the medium to long term, regardless of the discipline—be it running, cycling, swimming, skiing, or rowing.
But this raises an important question:
What does “high volume” actually mean?
Is it the same across different endurance sports?
For example, does 15 hours per week of training carry the same physiological weight in running as it does in cycling?
At first glance, endurance sports may seem comparable: they all involve cyclic movements repeated over prolonged durations. However, each discipline has its own biomechanical and physiological characteristics—such as mechanical load, muscle recruitment patterns, and impact forces—that can lead to markedly different internal responses and so load/stress.
This means that “high volume” may not be a universal concept, but rather a sport-specific one. The same number of training hours could impose very different levels of stress depending on the endurance discipline considered.
In this context, comparing running and cycling could be particularly interesting—especially in terms of muscle damage and inflammatory response when the training volume (in hours) is matched.
This question is highly relevant for:
triathletes
athletes using one discipline as cross-training
So, what happens when we compare the same number of hours of running and cycling? Do they induce the same degree of muscle damage and inflammatory response?
A study published by Nieman and Colleagues (Appalachian State University, USA) in 2013 on Brain, behaviour and immunity tried to answer this question. (1)
WHAT DID THEY DO?
13 well-trained runners and 22 well-trained cyclists (age 35, VO2max 70) were recruited.
For 3 days in a row, they ran on treadmills (the runners) or cycled on their own bicycles on an indoor trainer (the cyclists) for 2.5-h at 70% of VO2max, which corresponds to high zone 2 or low zone 3 in a 5/7 zones model.
Using blood samples taken the morning after the third training day, muscle damage and systemic inflammatory response and was compared between running vs cycling.
