by Dr. Chad Kerksick PhD August 27, 2021 4 min read
I have a few questions for you to consider before we dive into this article.
First, how many people do you know who do both resistance training and cardio style training? Quite a few, right?
How many of those people do both types of exercise during the same session?
Maybe not as many, but I still think many people do both types of training during one trip to the gym.
How many readers are coaching or working with clients and have recommended someone to do both types of training?
Again, I’m thinking we still have a good number of people.
Finally, how many of you have heard someone (usually the most "brotastic" of all bros out there) say they don’t do cardio, because they want to maximize their muscle gain or they don’t want to lose the muscle they have gained as a result of doing cardio?
My point of asking you those questions is to get you to see how the results of this study offer meaningful insight into these types of scenarios.
What is concurrent training? It is most commonly defined as when someone completes both a cardio and strength session in one workout.
The ‘interference effect’ occurs when the magnitude of strength, performance, or body composition changes are reduced or negatively impacted as a result of concurrent training.
A scientific study was recently published in the August 2021 issue of the European Journal of Applied Physiology that examined the impact of strength and muscle changes when adding some cycling cardio to a resistance training program .
In this study, the authors took a small group of younger and older men who were both experienced with resistance training.
The younger group had to have at least 5 years of resistance training experience while the older group needed at least 20 years of resistance training experience.
To be allowed in the study, the study participants were required to continue following their normal resistance training program, which consisted of four workouts per week (two upper and two lower body workouts).
A separate group of the younger and older participants were required to complete a cycling-based interval training program three times per week in addition to completing their normal four days per week resistance training program for a total of 10 weeks.
For the first six weeks, the cycling program increased from 45 minutes of 75% of maximum heart rate (Max HR = 220 – age) to five intervals of six minutes using intensities between 75 – 90% HRMax.
Before and after the 10-week cycling program, participants had their body fat assessed and a muscle biopsy taken.
Inside the muscle researchers measured how big the actual muscle fibers were and also measured the amounts of various enzymes that impact how capable people are at completing endurance type activity.
In the group of people that did the additional cycling exercise, significant improvements in succinate dehydrogenase activity (a key enzyme involved in oxidative metabolism) and capillary density occurred.
Both of these changes are favorable adaptations and basically mean the muscle improved its ability to perform aerobic activity.
In addition, strength measurements and body composition changes were assessed.
Over the course of 10 weeks, both groups were able to successfully maintain their strength levels, which defies the cries and fears of those out there who skip cardio, because they are concerned they will lose strength.
What changes in muscle size?
Did adding cardio cause atrophy or loss of muscle?
No, it did not.
When the average size of muscle fibers found in the muscle samples were analyzed, the results showed that fiber size did not change when compared to the fibers before the exercise program began.
These results tell us that over a 10-week time period, adding three, 45-minute bouts of cycling each week to people who were already doing resistance training led to significant improvements in oxidative capacity of the muscle without causing any loss of strength or muscle mass.
In fairness it is important to point that a no-cycling control group was not studied in this study and compared against the other group.
As a result, it is possible that adding the cycling program may have allowed for people to successfully maintain strength and muscle, but that their increases might have been greater if the cardio had not been included.
OK, how do we put this information to work for us?
First, people who do both cardio and strength sessions can maintain muscle mass and strength levels over a 10-week period, while also stimulating significantly greater improvements in oxidative capacity inside the muscle.
Thus, people who train both ways should not fear losing strength or muscle.
Second, training concurrently is an efficient way to train that results in improvements in health and stimulates very positive adaptations inside our muscles.
Chad Kerksick is currently an Associate Professor of Exercise Science and Director of the Exercise and Performance Nutrition Laboratory at Lindenwood University. Dr. Kerksick earned his PhD in Exercise, Nutrition, and Preventive Health in 2006 and since that time has worked as a university professor teaching classes and conducting research in areas related to exercise and nutrition. He is currently recognized as an academic fellow, the highest academic honor given by professional societies, of the American College of Sports Medicine (FACSM), National Strength and Conditioning Association (FNSCA), and the International Society of Sports Nutrition (FISSN). He also is certified as a strength and conditioning specialist (CSCS*D), personal trainer (NSCA-CPT*D), and sports nutritionist (CISSN). His laboratory, the Exercise and Performance Nutrition Laboratory (www.lindenwood.edu/EPNL), conducts rigorous, high-quality research investigations devoted to examining the impact of exercise and nutritional interventions of health, performance, and recovery of a large number of populations.
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