This post is taken from the Vitamin. Every Thursday, I drop some knowledge bombs on your face to help you reach your goals faster while avoiding all the bullshit.
When you think of resistance training, the word ‘flexibility’ likely doesn’t come to mind. But what if resistance training could improve your flexibility and range of motion?
A recent systematic review and meta-analysis by Alizadeh and colleagues aimed to evaluate the effect of chronic resistance training (RT) on range of motion (ROM) compared to stretch training to see what, if any, benefits resistance training had on range of motion. 1
What did the researchers do?
In order for studies to be included in the review, they must have fit the following inclusion criteria:
- Studies that separately compared the training effects of RT exercises with a control group, stretching group, or combined stretch and RT group on ROM in healthy participants
- Controlled and randomised controlled trials
- Longitudinal designs
- Excluding studies that investigated combined effects (i.e., aerobic training)
A total of 55 papers were included, with 2576 participants with a mean age of ~24 years, and a low risk of bias was indicated.
What did the researchers find?
The main finding of this study was that resistance training with external loads could improve ROM (the only exception was bodyweight training, which showed no significant changes in improvements in ROM).
Thus, stretching prior to or after resistance training may not be necessary to enhance flexibility.
Further, there were no significant differences between RT and stretch training or between RT and stretch training combined compared to stretch training alone.
When examining additional variables, both trained and active individuals increased ROM from RT, while untrained and sedentary individuals had a higher significant magnitude of change.
Finally, there were no differences between sex, contraction type, age, training duration, or frequency.
Practical applications
Overall, it appears that resistance training can be just as effective as stretching in improving range of motion.
When comparing resistance-training-only vs. stretching-only, there were no significant differences in ROM. Additionally, resistance training + stretch training vs. only stretch training led to no significant differences in ROM.
The trend seems to be that resistance training alone is as good as stretching at improving range of motion. Further, adding stretching to resistance training doesn’t lead to further improvements in range of motion.
Practically speaking, if you only include stretching in your program because you think it’s necessary, or your goal is to improve flexibility for certain exercises with a goal of building muscle and strength, you could drop stretching entirely without worrying about losing out on the range of motion benefits.
One exception to the above is bodyweight training, which doesn’t lead to improvements in range of motion like traditional strength training (using dumbbells, barbells, or machines and cables), likely because:
a) there isn’t enough of a stimulus placed on the muscles to force improvements in range of motion, and
b) in most bodyweight movements, you’re limited in how far you can ‘stretch’ the muscle. For instance, a push-up will be limited by the floor, whereas you can get a pretty deep stretch on a dumbbell bench press due to being elevated on a bench.
All of this probably flies in the face of what you might currently believe, especially considering how much emphasis is placed on stretching in fitness routines.
But resistance training improving range of motion isn’t that far-fetched when you consider that taking a muscle through a full range of motion under load is a form of dynamic stretching (versus static stretching, where you hold a stretch in one position for a period of time).
For example, there’s evidence to suggest the eccentric component––the part of a lift where the muscle is lengthening under tension (e.g., the bottom of a Romanian deadlift)––leads to greater increases in muscle fascicle length and an increase in muscle fascicle length can improve range of motion by allowing the muscle to stretch and contract over a greater distance. 2
Should we even bother stretching at all?
It depends, and context is important.
If your goal is to improve general flexibility/ROM, then it makes sense to include some form of stretching (because specificity is key). But in order for stretching to be effective, you need a dedicated stretching program that forces adaptation––i.e., the type of stretching that tends to be extremely uncomfortable (read: fucking sucks), not the ‘gentle’ stretching most people tend to do. For instance, Pandini and colleagues investigated the effects of static stretching on range of motion and found that, indeed, static stretching does improve range of motion (albeit to a small degree). However, for static stretching to be effective, it requires high volume and intensity. 3
But if you want to improve flexibility/ROM to help you get into specific positions, then stretching likely isn’t as important as once thought. If you want to get better at squatting, for example, spending more time in a squat position or squatting more frequently with intent (i.e., standardizing depth and trying to achieve more depth over time) might be more effective.
That being said, you can still include some form of stretching to help with this, but if you’re short on time or don’t want to have so many variables in your program, resistance training alone will suffice.
It’s also important to remember that too much stretching––especially before starting your strength training program––could decrease force production, which could negatively affect your performance. 4
If you want to stretch before a workout, dynamic stretching seems to be a good middle ground.
Spending 5-10 minutes on a warm-up before training that includes some dynamic stretching (e.g., leg swings or arm circles) doesn’t seem like a bad idea and can be included.
At the end of the day, if stretching helps you get closer to your goals, you’re able to invest the time to do it properly, and you enjoy it, then continue doing it. But if your goal is to improve ROM so you can get into certain positions (like a squat), resistance training can be just as effective.
Thanks for reading. If you enjoyed this, you’d love the Vitamin
95% of my new content is only being sent to my email list. One email every Thursday, filled with actionable, evidence-based fitness advice to help you with your goals. If you enjoyed this, you’d love my emails. You can learn more and subscribe for free here.