Will cardiovascular training kill strength

One of the most poorly understood interactions in the sport and fitness world is that of cardiovascular training and strength levels. One of the most prevalent misconceptions is that cardiovascular training or “Cardio” will hinder or even reduce strength levels. In particular low intensity, high volume cardio has been touted as a strength killer.  Many will agree with this statement and anecdotally it seems to hold a lot of truth. Then we look at field athletes such as rugby players for example. Some have pretty impressive strength levels as well as excellent cardiovascular conditioning. How do they achieve this if the training methods counteract each other? In addition why do so many scientific studies with tight control and experimental design show conditioning to be improved alongside strength and power? There are similar misconceptions of strength in the endurance world. Endurance athletes believe strength training makes them slow and bulky.  How can so much confusion and mixed opinions exist in this.

The answer all comes down to one simple factor -Load! When we use the term load we are not referring to load as a weight, we refer to it as external stress. In this case the stress is training volume or overall training load. Typically cardiovascular training, especially the low intensity variety, is done in high volume to have effect.  Large volumes of training have high energy demands. These demands can be hard to meet nutritionally. In addition to this, large volumes of training can accumulate considerable microtrauma and damage to muscle cells. In practical terms there is an accumulation of fatigue.

If one wishes to increase or maintain strength levels one must train to the upper limits of one’s current ability. The neuromuscular system improves when its current capacity is placed under higher demands than it is capable of meeting. Over time and consistent stimulus it responds and adapts becoming more efficient. This is the basis of a strength program. Progressive overload is the simplest mechanism for adaptation.

An athlete must lift enough to elicit adaptation and increase strength.
An athlete must lift enough to elicit adaptation and increase strength.

When we train while fatigued it has obvious implications for what can be achieved. One will simply not be able to reach a level of intensity that would be considered maximal or required for any real stimulus. In short we cannot train hard enough to push our limits. With the result that the mechanism of progressive overload is never achieved as we remain well within our limits. Not being able to train maximally or at our upper limits will make it extremely difficult to see any improvements in absolute strength. In addition, prolonged periods of training in which we fail to reach intensity will result in detraining. If we don’t use it we lose it. We can lose strength as we don’t really get to the point where it is stressed.

Large volumes of cardio training take up a lot of time in our schedules. Larger volumes have been shown to be very effective in terms of improving cardiovascular conditioning. The issue is allowing enough time in a week to complete cardio, recover and then train strength. If it is not scheduled carefully there is bound to be latent fatigue when going into the subsequent training sessions. This is where issues arise and cardio begins to have a negative impact on overall training effectiveness.

Another argument is that physiologically the adaptations of cardio training counteract those of strength training. This is usually the argument used to explain why cardio kills strength. In reality the structural adaptations are largely defined by genetics. Smaller people tend to suit endurance sports just like larger individuals are suited to power type sports. Yes there is some influence of training but generally speaking we naturally sort into the sports we are suited to at a young age. Our size will influence our success in a given sport and there’s not much an individual can do about it. Larger people can be very well trained cardiovascularly but must move more mass and therefore tend to be slower as a result. Likewise smaller endurance athletes can be very strong pound for pound but will simply lack the mass to shift heavier weights. This is a major reason for weight categories in strength sports such as weightlifting.

In short genetically we are predisposed to certain characteristics which fool us into thinking the type of training we do is the reason for our abilities or weaknesses.  When looking at concurrent training the main factor that influences our improvements is fatigue. If training is carefully planned and one does not overtrain a capability or underecover from sessions, we can improve both simultaneously. Looking practically it is a lot easier to focus on one or the other but this is not always a possibility.

The point of the article is to highlight the fact that one can train strength and cardio simultaneously and see improvements in both. Strength can go unhindered and endurance can be improved with increases in strength. Poor understanding of the relationship between the two has led many individuals to neglect their conditioning in favor of strength or vice versa. When planning a training program one should consider the length of time it takes to recover from different training types. Progress will be ensured if one considers the differing timescales of recovery and appropriate training stimulus needed to promote adaptation. When this is accounted for concurrent improvements in both strength and cardiovascular conditioning are very achievable.

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