Hi Fitness Peeps – just wanted to give you a heads-up.
Brad Schoenfeld and I just got a paper published in Sports Biomechanics titled:
We wanted to see how increasing the lever length and posteriorly tilting the pelvis affected core muscle activity in a plank, so we compared four plank variations:
traditional plank
long lever plank
posterior pelvic tilt plank
long lever posterior tilt plank (LLPTP)
By the way, here’s how you perform an LLPTP (and HERE is an article detailing the form):
Results
Discussion
As you can see, the traditional plank doesn’t activate the core very well. This doesn’t imply that it’s a useless exercise; quite the contrary. It’s a beginning level plank that every lifter should master prior to progressing to more challenging variations.
Lengthening the lever actually had a greater affect on core muscle activity than posteriorly tilting the pelvis. This surprised both Brad and I, who hypothesized that the PTP would have a greater affect than the LL.
Combining the PTP and LL was, to no surprise, the most effective strategy for maximizing core muscle activation in a plank. With the LLPTP, you get over 100% of MVC out of the upper rectus abdominis, lower rectus abdominis/internal obliques, and external obliques. This is a big bang movement for the anterior core (not the erectors though – they barely get worked in any of the tested plank variations).
Take home message: planks can be highly effective when you know how to modify them and increase the challenge. This is something that I learned from Pavel Tsatsouline, who thought up the RKC plank years ago. Give the RKC plank or the LLPTP a try and see for yourself how demanding they can be!
Thanks, Bret. Very informative. While not in the study, how would you rank the LLPTP & RKC variations vs. a one-arm/one-leg plank?
Hmmm, good question. I think one arm/one leg might match the oblique activity but not the rectus abdominis activity seen in the LLPTP/RKC variations.
I love these kind of electromyography studies !! good job guyz !! 🙂
Thanks for bringing attention to your findings Bret and Brad.
I find isometrics tedious. Would working on pushups with a dowel rod on my back and squeezing my glutes or doing ab rollouts from my knees with dowel rod and glute squeeze be just as useful?
Since doing pushups like that especially squeezing my glutes at the bottom I found clap pushups surprisingly easy my neutral spine probably went to crap but I got quite a bit of height.
Am I the only one who finds isometrics a bit tedious? I don’t know if tedious is the right word.
Yes, it’s very useful – I do this with ab wheel rollouts too. Trust me, I can’t stand long duration isometrics either. But the point of the LLPTP and RKC planks isn’t to increase duration so much as it is to maximally fire glutes/core. I do 2 sets of 10-15 seconds. When you know you just have to do 10-seconds, you go all out isometrically and get a surprisingly effective training stimulus.
Thanks for the reply.
I’ll try that before a workout or after a sedentary day.
Bret:
Could you explain how you get greater than 100% MVC with the LLPTP without external stimulus?
Jim, this happens all the time in research. MVIC is just a maximum isometric contraction used for normalization. Often this level of activation is exceeded during heavy or explosive movement. Now, with the LLPTP, you’re attempting to push your pelvis posteriorly with maximum force, but the hip runs out of ROM, so you’re fighting against your own anatomy. That, in combination with the stability required from the plank and long lever, explains the very high levels of EMG activity.
Thanks for the explanation Bret.
Bret,
I am not trolling. I watched a video of someone saying that surface EMG is not very reliable.
Video here: https://www.youtube.com/watch?v=6el9KxPnhl8
He said that surface EMG is just reliable to tell if a muscle is firing and needle EMG is more reliable but can be dangerous.
Can you go into more detail about the reliability of surface EMG ?
Thanks man.
Will, coincidentally, I just had a discussion with Sebastian here: https://www.facebook.com/SebastianFitnessSolutions/posts/823092601058641?comment_id=823155244385710&offset=0
I will probably write up a blogpost on EMG, tackling some of these concepts. There are definite flaws with EMG, just as with any technology, but the biggest flaws aren’t typically mentioned in these arguments and many of the criticisms aren’t that big of a deal IMO. EMG is my favorite tool in sports science and helps us answer a ton of questions.
Thank you for the quick reply. Yes, an EMG write up will be very helpful.
Thanks Brett for the tip. I was wondering if you have, or could, comment on how to make the side plank more effective. Pelvic tilt action? Most effective elbow position? Stack the feet or stagger them?
Terrific information, but I have a question. Are the measurements of EMG value based upon doing the exercises for the same duration? In other words, do the measurements assume that each exercise is being done for the same time period? If so, how would doing the traditional plank for, say, 2 minutes, compare to doing one of the variations for 30 seconds? (And 30 seconds is a long time if you are doing the LLPTP with maximum muscular contraction, as I assume you should.) Or am I missing something here (entirely possible, since I don’t have the academic background to fully understand this field.)
Thanks for your enlightening work, Bret.
And stir-the-pot with feet on a tall box and forearms on a 45cm ball kick the shit out of LLPTP. Try them.
You continue to provide great information. Thank you!
I appreciate the intelligent questions from the folks above as well. I was just doing some rollouts yesterday and really squeezing the glutes while performing them. Huge difference!
It’d be cool to see this done with a few other variations like stir the pot, or ab wheel rollouts. Obviously quite a bit different due to the movements, but could be interesting to see if one produces greater peak activation.
A reverse plank is likely to to hit the erectors more. What do you think?