Build strength and endurance at the same time with hybrid strength training.

When I started training at the gym (I was 19 and knew nothing) there were few very common "truths" that were non negotiable. Some to mention: carbs are evil, you must get protein right after workout and cardio kills muscle growth. I'm much wiser now but it is sad to see all of these statements are still alive and doing well (unfortunately).

In this post I want to elaborate the last one, wich to be fair has the most truth in it. And it surely is the the most common questions in hybrid training. And the question is: Can I build strength and endurance at the same time — or will one ruin the other?

What is Concurrent Training and how is it different from Hybrid Strength Training?

Concurrent training means exactly same as hybrid training, just hybrid seems to be more commonly used. Hybrid training tho can mean multiple things: training strength and endurance, training two energy systems, training using bodyweight and weights etc. Concurent training is a term used in scientific literature and means simply combining resistance (strength) training with endurance (aerobic) training within the same program — which is the core of being a hybrid athlete as i see it.

But this type of training has historically been said to cause something called the interference effect. This term refers to the phenomenon whereby training one quality impairs the development of another. So in this case endurance work might reduce strength or muscle growth. Strength training has also been feared to affect negatively to endurance performance. These are both true but the real question is to how much extent? And is there a way to get around it? Let’s see what does the science actually say. 

🔑 Key Findings from the Meta-Analysis by Wilson et al. (2012)

I found a good meta-analysis from 2012 exploring the interference effect. Since it is a meta-analysis it is mostly focusing on broader picture such as volyme, the type of training and intensities, but it gives a great overall picture of the effect.

1. Yes, you can gain muscle and strength with hybrid training.

Strength-only training produced the highest gains, but concurrent training still resulted in solid improvements:

If compared strength only and concurrent (hybrid training) strength gains were slightly lower in concurrent group (1.44 vs. 1.76 effect size), wich means that you will get significant strength gains while training endurance at the same time but the progress will be just approximately 20% slower. More about the factors influncing this later.

Muscle growth (hypertrophy) was also reduced (0.85 vs. 1.23). The difference is larger, but still: muscle will grow, just a bit slower. Obviously, there is a "glass ceiling" with hypertrophy, meaning if you really push endurenace aspect of training it is hard to gain muscle as endurance stimulates mostly slow type 1 muscle cells, but more of this later. Also, it is unknown if the athletes in the concurrent training programs were advised to eat properly to match the energy expenditure of training twice as much. I doupt that the hypertrophy would suffer as much if they had ensured proper energy intake?

Conlusion: Yes, you’ll get results — just not quite as fast as if you did strength-only training.

2. Running interferes hybrid strength training more than cycling

Running led to more interference in strength and muscle growth than cycling. Likely due to more muscle damage and longer recovery needed from running. This is most likely because in cycling there is no excentric work at all. Excentric work means the part of movement where muscle has to break, for example in squats lowering yourself down. In running the excentric work happens when you land on your foot, and you have to resist the impact. This is more taxing for the muscle and nervous system than cycling where pedaling is done only by concentric muscle work. This was also proven in studies done with rowers: Rowing with resistance training resulted same strength and hypertrophy gains as resistance training alone, meaning experienced endurance athetes as rowers do not have to lower the rowing volume in order to get stronger. (Bell et al. 1997)

Notable is also that running also resulted better Vo2max gains and lower bodyfat than cycling. This also rises a question if running and cycling was done in the equalivent volume from the perspective of improvement to VO2max, would the difference in interference effect be as dramatic?

Conclusion: For better strength development, hybrid athletes may prefer mainly cycling and rowing during strength-focused phases. Running should be low volume and short distance. 

Running has stronger interference (negative) effect on strength than cycling. During strength season favor cycling or rowing over running.

3. Splitting strength and endurance on different days works better

Training strength and cardio on separate days or at least 6+ hours apart led to better results than doing both in the same session. Same-day training caused slightly more interference, especially if endurance was done before strength. For strength gains it is important that body is well recovered, for endurance it is not equally important, as long as you are able to follow the plan from the HR and duration aspect.

➡️ If you’re doing both in one day: sprint or lift in the morning, run later in the day — or vice versa. For best results split sessions to different days.

4. Volume and frequency matters

The more endurance training you do, the more it can interfere with strength gains.

In the study the correlation between longer endurance sessions and the negative effect on power output and rate of force development was almost linear. I have noticed this personally when coaching football (soccer) players, there is barely any proggress in vertical jump during the season even when strength and power output are trained frequently. This is because high volume of running in the games and in the practice. This is why different seasons for endurance and strength are recomended. (see the image below). However, if none of the strength or speed work would not be done during the season the decline might be even bigger.

➡️ If strength is the priority, keep endurance sessions short.

Volume of endurance training correlates negatively with strength, power and hypertrophy gains.

5. Power is the most affected adaptation

Compared to strength or size, power (explosiveness) took the biggest hit from concurrent training (see the image above). For power I would recommend short season without any endurance training at all, or just 1-2 short sessions done with bike or rower.

➡️ If you're training for power (e.g. sprinting or Olympic lifting), consider cycling endurance phases separately.

6. Interference is mostly in the lower body

Endurance training primarily uses the lower body — and that’s where interference shows up most. That is why upper-body strength and size were less affected. This is why upperbody hypertrophy and strength can be recomended also during endurance season. Personally I like doing high volumes of pull-ups & push ups with my runs.

➡️ This gives more flexibility for combining upper-body lifting with lower-body endurance training.

7. Endurance capacity is not affected

Adding strength work did not harm VO₂max improvements. This is misconception fo some endurance athletes. Just be mindful of not doing extreme leg days that cause excessive soreness.

➡️ You can still build a strong aerobic base while lifting heavy.

8. Concurrent training reduced body fat the most

Programs that combined resistance training with high-intensity endurance led to the greatest fat loss.

➡️ Enough said: with hybrid training you get ripped.

Reference

Wilson, J. M., Marin, P. J., Rhea, M. R., Wilson, S. M., Loenneke, J. P., & Anderson, J. C. (2012). Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. Journal of Strength and Conditioning Research, 26(8), 2293–2307. https://doi.org/10.1519/JSC.0b013e31823a3e2d

Bell, G, Syrotuik, D, and Socha, T. Effect of strength training and concurrent strength and endurance training on strength, testoster- one, and cortisol. J Strength Cond Res 11: 57–64, 1997.