Thursday, November 15, 2012

Shoulder Presses Ain't for Delts, Only! Standing, Seated w/ BB or DB, They Also Hammer the Core, Biceps & Triceps

Flex Wheeler doing BB presses in what vcertainly isn't the ideal position for the lower back - imagine him doing that standing *uhoh*
Don't worry, I am not going to repeat my SuppVersity Facebook news post on the activation of the rectus abdominis, the obliques and the lower back muscles many of you 'liked' on Facebook. I am rather going to expand on it by presenting the data from the unofficial follow-up (Saeterbakken. 2012). Before I do that, I will yet give you the usual preview of today's installment of the SuppVersity Science Round Up I am doing every Thursday (1PM EST, live!) with my friend Carl Lanore from Super Human Radio (in case you did not notice, the number of real scientists on the show has risen exponentially within the last weeks, so I highly recommend you download a couple of other podcasts as well).

SuppVersity Science Round Up - Preview

Just like today's blogpost the focus of today's Science Round Up is actually going to be on training and exercise and don't worry, we won't just be whimpering that people get way too less of it.
  • Twin study shows: We all age, but exercise determines the consequences on your health
  • Hormonally (over-)demanding plyometrics!?
  • HIIT, light intensity steady state and the thyroid gland
  • NSAIDs: Go or no go for an athlete interested to build muscle?
  • Glucose, insulin and their muscle building effects
  • Could your own sweat protect you from skin cancer?
  • Chinese medicine strikes again: P. Lobata stops liver fibrosis in its tracks
  • Non-reactive form of vitamin E could be gold standard for cancer therapy
By now you should know the procedure and will thus be aware that it is unrealistic to assume that Carl and I are going to pack all these, let alone any of the auxiliary items on my list, into one show. My best advise would be to tune in live at 1PM (or downlaod the show ~2h later from the sidebar link, here at the SuppVersity), listen and come back tomorrow, to read about the topics that did not make it into the show in the SuppVersity Science Round Up Seconds.

Back to where we came from: The shoulder press!

After the obligatory heads up on the potential topics of today's SuppVersity Science Round Up, let's now get back to the shoulder press. Even if you did miss the facebook post on how it activates the abs, the obliques and the lower back, the other day, you should remember from the SuppVersity EMG Series that different forms of the shoulder press (including behind the neck presses, which are not part of the study at hand) will yield differential activation patters in the musculature of the shoulder girdle.
Navigate the SuppVersity EMG Series - Click on the desired body part to see the optimal exercises.
In the follow up to their core activation study from last year, Saeterbakken and Fjmland did once again go one step further than Boeckh-Behrens & Buskies. Instead of measuring just the usual suspects, i.e. muscles you actually want to train when you do shoulder presses, the researchers expanded their existing data on the activation patters by measuring the activity of biceps and under both, seated and standing exercise conditions with a barbell or dumbbells as well as the 1-RM strength on the individual exercises.

With the auxiliary muscles, the body position, the loading modality (measured during sets of 5 reps at 80%)  and the maximal weight the participants were able to press in each of the four 1RM max attempts Saeterbakken and Fjmland's data on the shoulder presses, alone, is therefore about as extensive as Boeckh-Berhens' and Buskies' data on four or five totally different exercises. Plus their subjects, 22y old lifters with on average 5 years of training experience may be a better model for at least some of you.
Figure 1: Activity pattern of the deltoid and auxiliary muscles (* indicated p < 0.05; data based on Saeterbakken. 2012)
Let's get to the results, now. As the data if figure 1 goes to show you, there are a couple of statistically significant differences, which are in some cases (the asterisks on the lowest level, directly above the bar) related to the training equipment (i.e. dumbbell vs. barbell), in other cases, such as the activation of the posterior deltoid, for example due to doing the exercise standing vs. seated (asterisks about the lines connecting the respective bars denote p < 0.05).

For those who missed the original Facebook post on the first Saeterbakken study (Saeterbakken. 2011), here is a brief summary: Using electromyographic activity (EMG) of the superficial core muscles (i.e. rectus abdominis, external oblique and erector spinae) and comparing the data of seated, standing, bilateral and unilateral dumbbell shoulder presses the researchers found that their 15 healthy male study participants had the greatest core activitation, when they performed their five repetitions at 80% of one-repetition maximum... 
  • rectus abdominis (abs)
    - standing unilaterally
  • external oblique
    - standing unilaterally  
  • erector spinae (lower back) - standing unilaterally
For some of the muscles the different positioning does not really matter, but in each and every case the standing unilateral dumbbell press had a slight (if insignificant) edge on the rest of the exercises.
Just as in the unofficial prequel to this 2nd study by Saeterbakken and Fimland I discussed on Facebook earlier this week (see box to the right for a summary, if you don't want Facebook and the world to know the color of the boxer shorts you're wearing, today), the overall pattern that emerges from this very recent follow up study is that ...
"[...] the standing dumbbell press exercise, which was the exercise with the greatest stability requirement (standing + dumbbells), demonstrated the highest neuromuscular activity of the deltoid muscles." (Saeterbakken. 2012)
Now what's particularly intriguing to this result is that the superiority of the complex movements became obvious despite the fact that the subjects moved the least weight during this exercise. In the aforementioned study by Boeckh-Behrens & Buskies, for example, the exercises which allowed the greatest leverages, usually produced the highest muscular activity, as well.

How can we explain this difference?

Aside from the training status of the participants, the first thing that comes to mind is the rep range: While the subjects in the study at hand trained at a 5RM rep range (meaning they failed on rep 5), the sports students in the Boeckh-Behrens & Buskies study performed 10-12 reps and would thus necessarily have to use lighter weights. In conseuqence, every lbs more made a greater difference for the students, than for the 15 even-aged healthy men with an average of five years of strength training experience under their belts (they were no competitive powerlifters or o-lifters, though), who participated in the studies by Saeterbakken & Fjimland.

As far as the other parameter, the body position, was concerned the results are not as obvious as they were for the core muscles in the 2011 study by the same authors:
"Further, standing versus seated execution, and to some extent dumbbells versus barbell, both resulted in increased muscle activation of the deltoid muscles. Standing instead of seated presses raises the centre of the mass, and also provides a  smaller base of support as the contact points decreases from three to two, particularly when using a bench with a back-rest [comment: the back was set to 75°]. When using a pair of dumbbells instead of a barbell, the main difference is that the dumbbells must be controlled independently of each other. Hence, performing shoulder presses standing and with dumbbells should lead to greater instability." ( Saeterbakken. 2012)
Regardless of the intricate differences, though, the whole picture that emerges from the synopsis of both the 2011 and 2012 data Saeterbakken and Fjimland have collected is actually quite clear: Complex exercises and corresponding muscle activation patterns can make a very valuable tool in the arsenal of the experienced strength trainee.

A final word of caution and the real world difference you can expect

Are you looking for more shoulder exercises? Look no further read them up in the SuppVersity EMG Series and the respective part on the 'best' exercises for M. Deltoideus, M. Infraspinatus, Supraspinatus and Teres Minor (more...)
The lower back and the shoulders itself are however so liable to injury that even somebody with years of training experiences should start out with very light weights and see for 2 or 3 training sessions how his shoulders and lower back react. Against that background it does also appear questionable, whether it is wise to to include a heavily loaded variety (5-8RM) of the standing dumbbell shoulder press in the routine of any beginner or only slightly advanced trainee. The increased injury risk just is not worth it, because the complexity of the movement and the individual (often very) weak links will force a beginner to use very light weights. So light, in fact, that the original target muscle, which is obviously the shoulder, may not receive enough hammering, so that even in the fortunate case that they don't hurt themselves, beginners will probably see way better results with regular seated vs. standing dumbbell presses.
  • Boeckh-Behrens WU, Buskies W. Fitness-Krafttraining. Rohwolt. 2010.
  • Saeterbakken AH, Fimland MS. Muscle activity of the core during bilateral, unilateral, seated and standing resistance exercise. Eur J Appl Physiol. 2012 May;112(5):1671-8. Epub 2011 Aug 30.
  • Saeterbakken AH, Fimland MS. Effects of body position and loading modality on muscle activity and strength in shoulder presses. J Strength Cond Res. 2012 Oct 23.