Hi. Lately I’ve been running into an annoying problem of trying to do a challenging cardio workout but the endurance of my muscles fails before my cardio feels challenged. For example, if I am running, my legs feel tired before I feel my heartrate has been raised significantly, I do a lot of martial arts and do a lot of rounds on the heavy bag but I feel my legs and arms get fatigued faster than my heartrate and breathing. I’ve tried bouts of steady state training, as well as various intervals including HIIT. I think I’ve been blessed with good recovery when it comes to cardio, but is there something I’m missing here? Should I be working on muscle endurance? Or do I just need to find a different type of workout that I’ve never experienced before? Any insights are welcome!
All of answers are thought-provoking. I agree with Brian that because of your concerns, asking your doctor for a complete physical, including a lab panel may be a good idea. In addition to the comments suggesting adequate dietary complex carbohydrate intake is essential for adequate repacking of muscle glycogen, which provides the substrate essential for not only glucose metabolism, but for fatty acid metabolism, as well.
Also be sure to include at least one day/week for rest and recovery. Also be sure that stay adequately hydrated before, during and after your workouts.
Christine’s point makes sense to me. Sounds like you are perhaps doing more anaerobic work than aerobic. If you are getting over your aerobic threshold and tiring out your quads you many be working out to hard for a cardio bout. Have you tried a heart rate monitored as a measure of intensity? Obviously, if you are working at a heartrate of 85% or above of estimated max, for a long time, then you may be pushing too hard for aerobic training and at threshold of anaerobic.
Assuming this is not a medical issue, there are a few questions I would ask you….
Are you sufficiently warmed up at a lower intensity before your workouts?
Are you sufficiently fueled and hydrated? Is running or martial arts new to you for workouts? It may take working out at a lower intensity first to build muscle endurance–before you increase the intensity. If you are currently doing anaerobic (high intensity) bursts of exercise, your muscles will fatigue faster because it is different than muscle endurance.
Also, when you change modes of exercise, you will work your muscles in different ways and it could take some time to adapt. Hope some of this helps!