A brand new meta-analysis just published this month in the Journal of Strength and Conditioning Research has added new insights to this question...

It has been known for a long time that too much endurance training done concurrently with resistance training interferes with power and strength, and at least to some degree, muscle hypertrophy.

But questions and controversies have continued to swirl around this issue for years with no resolution...

How much endurance training? What volume, frequency and intensity? What kind of endurance training or cardio? None of these questions have ever been fully resolved and both experts and practitioners constantly argue about it.

Some coaches and athletes seem to believe that doing any endurance (cardio) training at all will make you as weak as a kitten and as scrawny as an 11-year old stamp collector. Some say it's a matter of dose and context - ie, only too much cardio in certain situations should be cause for concern. Others say adding cardio will only help you get leaner and the fears of muscle loss are overblown.

Finally, here are some answers. So you can quickly get to the bottom line I've compiled a punch list of the key points from this new research analysis below.

Concurrent weight training and cardio training - what the latest research says:

• Adaptations for resistance and endurance exercise are vastly different and in many cases conflict with one another, creating an interference effect (strength, power or hypertrophy decrements).


• NOT everyone experiences interference effects after concurrent training; some have even experienced gains.


• There are explanations available to explain these differences in results and they can be applied to minimize the detrimental effects of concurrent training and maximize the beneficial effects of adding cardio training to a resistance training program.


• Up until now, very little research separately identified which components of endurance training (type, intensity, duration, etc) are most detrimental to resistance training results and which outcomes (strength, hypertrophy, power) are affected to the greatest degree.


• Body fat drops to the greatest degree when cardio training is included along with resistance training, particularly moderate to higher intensity cardio. Thus, when fat loss is a primary goal, cardio can and should be done concurrently with resistance training.


• Power is most susceptible to decrements than strength or hypertrophy. Power athletes should therefore, be the most conservative with cardio / endurance training.


• Athletes who are not dependent primarily on maximal power and are only dependent on strength and hypertrophy may perform concurrent training without interference, provided the proper modality of cardio training is selected.


• Running produced greater decrements in BOTH hypertrophy and strength than cycling, when done concurrently with resistance training. This may be due to greater skeletal muscle damage caused by the high eccentric component of running. For example, distance running has been found to produce large increases in muscle damage whereas ultradistance cycling did not.


• A positive outcome of running is the greatest decrease in fat loss.


• The most dramatic fat losses occured with moderate to high intensity endurance training.


• Interference effects are body part specific. The decrement in hypertrophy and strength from running concurrently with resistance training was primarily in the lower body and not in the upper body.


• The greater the volume of endurance training, the greater the susceptibility to overreaching and under recovery, leading to interference effects.


• Duration of endurance training is a major factor in degree of interference when concurrent training is done. Strength athletes should avoid long duration endurance exercise (more than 20-30 minutes) that is performed at a high frequency (more than 3 days per week), to minimize any interference.


• Endurance athletes should not fear addding strength training to their endurance training programs because resistance training does NOT interfere with aerobic capacity.

In summary, this analysis showed that some concerns about the interference effects of cardio with weight training are legitimate - especially for power athletes and especially when large volumes (long duration and high frequency) of endurance training are performed.

However, the idea that you should never do any cardio or you will lose muscle and strength is not accurate.

These results confirm what a lot of bodybuilders and strength athletes have known for years from personal experience:

1. Moderate amounts of cardio can increase fat loss above what you can get with diet and resistance training alone, without interference in strength or muscle growth.
2. Cardio volume and duration should be kept to a very modest level when strength and muscle growth are primary goals.
3. Excessive running can decrease the size and strength of your legs.
4. Cycling may be a preferable form of cardio for strength and physique athletes.

This matches and confirms the recommendations I've made for body recomposition in the Holy Grail Body Transformation program

Tom Venuto, author of
Holy Grail Body Transformation System
(How to Gain Muscle and Lose Fat at the Same Time)
www.HolyGrailBodyTransformation.com <==== Click Here

References:
Wilson JM, et al, Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises, Journal of Strength and Conditioning Research, 26:8, August 2012..

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