Whatever your reasons for exercising you want to get results and get them in the shortest time possible. That’s why “concurrent training” is so popular these days. What IS concurrent training? It’s doing cardio and strength training on the same day or even within the same workout – circuit style. No doubt concurrent training is a timesaver – but is it as effective as doing cardio and strength on separate days after your muscles have had more time to recover?
Benefits of Concurrent Training
Concurrent, circuit-style workouts may be your only option when you’re time-strapped and have limited time to exercise. With a concurrent workout, you can knock out resistance training and get your heart rate up in the shortest time possible. The second advantage concurrent or circuit training offers is variety. Rather than doing 30 minutes of cardio and 30 minutes of resistance training you move back and forth between exercises. The back and forth flow between exercises make circuit workouts more mentally stimulating.
Are There Drawbacks to Concurrent Training?
Once concern about circuit training is the effect doing both forms of training during the same session has on strength performance. There are also questions about whether circuit-style workouts reduce cardiovascular benefits as well. Research shows circuit training even without cardio intervals between each resistance exercise meets the criteria for a cardiovascular workout – but barely.
Circuit workouts DO get your heart rate up high enough to get cardiovascular training benefits, assuming you’re not stopping to rest between each resistance exercise. You need to move quickly from exercise to exercise to keep your heart rate up. If you do cardio intervals like jumping jacks, high knees, butt kickers, etc between each resistance exercise you’ll maximize the cardiovascular benefits you get from a circuit workout.
Concurrent Training and Strength Gains
What about strength gains? Here’s where concurrent training may fall short. A study published in the Journal of Applied Physiology showed 10 weeks of concurrent resistance training and cardio cut strength gains by half. The good news is concurrent training led to greater fat loss than resistance training alone. So, if fat loss and general conditioning is your primary goal, concurrent, circuit-type workouts are a good way to achieve your objectives.
Another study looked at the effects different intensities of aerobic exercise had on strength training performance when strength training was done on the same day as aerobics. Some participants in the study rested four hours after aerobic exercise while two other groups rested eight hours and 24 hours respectively before tackling a strength-training workout. Still another group did no aerobic exercise prior to strength training.
The results? Whether the participants did moderate-intensity aerobic training at 70% of V02 max or high-intensity, interval training at 85% of V02 max didn’t seem to affect the results. The researchers found participants who only recovered for four or eight hours between aerobic and strength training were able to do fewer leg presses. On the other hand, their bench press performance wasn’t affected at all. This data suggests aerobic exercise involving large muscles in the lower legs may reduce strength performance on lower body exercises when you do them on the same day.
Although some research shows concurrent training interferes with strength performance, others don’t. Why are the results so conflicting? A number of factors can impact the results – amount of recovery time between session as well as duration and intensity of the strength and aerobic sessions.
Still another study showed muscle strength is less affected by concurrent aerobic training than muscle power. This study also showed differing effects based on the type of aerobic training. Running interfered with lower body strength more than cycling did. In fact, research suggests combining strength training with low-impact aerobic may actually enhance muscle gains while offering cardiovascular benefits. Chalk one up for circuit training.
Does Concurrent Training Send “Mixed Messages?”
If concurrent training DOES interfere with muscle growth, how might it happen? Resistance training activates pathways like the mTOR pathway, which promote muscle growth. Resistance training has an anabolic effect. In contrast, cardiovascular exercise inhibits the mTOR pathway and has a catabolic effect. Concurrent training sends your muscles “mixed messages.”
If your only goal was to build strength and muscle mass, resistance training without cardio would be the most effective way to do it. The drawback is you would get little or no cardiovascular benefit. Plus, if you’re trying to lose body fat so you can see those muscles, cardio helps.
Another reason concurrent training limits strength gains relates to the fatigue factor. Cardiovascular exercise is tiring. As a result, it may reduce the intensity with which you can resistance train when you’re doing concurrent training. When you’re fatigued from cardio, it’s harder to eke out the last rep or two you need to maximize your muscle growth and build strength. In fact, most people use a resistance that’s 50% to 60% of their one-rep max when circuit training. This amount of resistance isn’t optimal for muscle growth or strength gains.
Circuit training mostly enhances muscle endurance and functional fitness while burning calories. It’s a good workout for general conditioning and fat loss – but not necessarily the best approach for muscle hypertrophy or strength gains.
The Bottom Line
Some evidence suggests concurrent aerobic and strength training reduce strength performance, although it may vary with the intensity and volume of each session. Concurrent training is more likely to interfere with lower body strength performance and may have little or no effect on upper body training.
The take-home message? If your goal is to build strength or mass in your lower extremities you may get better results by doing aerobics on a day you’re not strength training. For days, you want to work on general conditioning, muscle endurance, and fat loss, concurrent training or a circuit style workout is a good option.
References:
Bodybuilding.com. “Ask the Muscle Prof: What’s the Best Cardio for Preserving Mass?”
J Strength Cond Res. 2012 Aug;26(8):2293-307. doi: 10.1519/JSC.0b013e31823a3e2d.
IDEA Health and Fitness Association. “The Effect Of Concurrent Training”
“The Effect of Concurrent Training” Len Kravitz, Ph.D.
Strength and Conditioning Research. “Does aerobic exercise interfere with strength-training adaptations?”
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