If you’re on this article, there’s a good chance this is because I referred to this link during a video on chest hypertrophy (https://youtu.be/wa8vJg-h_a8).
If you’re after the references, they can be found at the bottom of the article. If you’re after the discussion on whether the extra growth from training at longer muscle positions is short-lived, this is right here:
Is The Extra Growth from Longer Length Training Short Lived?
As noted in the video, some speculate the extra growth from training at longer muscle positions is short-lived.
To understand the reasoning and evidence behind this speculation, we need to quickly understand how muscles may grow.
Muscles are organized in hierarchical layers. Within the whole muscle are fascicles, within fascicles are muscle fibers, and within muscle fibers are myofibrils.
Myofibrils contain sarcomeres. And sarcomeres are the source of where muscles generate their force.
It’s very likely one of the most frequent ways muscles grow is through adding sarcomeres in parallel.
However, it is also very likely muscles can grow by adding sarcomeres in series.
There is some evidence from animals, and indirectly from humans, that increases in sarcomeres in series may be a limited adaptation. Namely, this adaptation plateaus after 3-8 weeks, with no significant increases thereafter.
Technically speaking, increases in the size of other things in the muscle tissue can contribute to size increases (like growth of the sarcoplasm), but we don’t need to worry about that here.
Anyhow, it has been speculated the extra growth seen from training muscles at longer lengths is entirely reflective of an increase in sarcomeres in series.
And since this adaptation might be short-lived, some say this means that once this adaptation has been attained, training at longer muscle lengths won’t produce extra growth compared to training at (relatively) short muscle lengths, rather the growth will be similar.
Now, some of you might be confused: how can an increase in sarcomeres in series (length increase) make the muscle bigger in size, as measured by overall muscle cross-sectional area or thickness? I certainly understand how this can be confusing to wrap your head around, but an increase in sarcomeres in series can probably increase fascicle length, and an increase in fascicle length has been mathematically demonstrated to cause an increase in whole muscle cross-sectional area (this would also mean an increase in fascicle length can increase muscle thickness too).
With that understood, is it true the extra growth from longer-length training is just more sarcomeres in series?
At this time, I don’t think a definitive answer can be given. The evidence for this is limited and indirect.
I brief some of the main data below. Note that in human studies, it’s believed that increases in fascicle length reflect an increase in sarcomeres in series, while an increase in pennation angle reflects an increase in sarcomeres in parallel.
Support for the extra growth from longer length training being shortlived:
- In this paper, training with a partial at long muscle lengths built more muscle than a partial at short muscle lengths. Increases in fascicle length (thought to reflect increases in sarcomeres in series) were better for the long lengths, but increases in pennation angle were similar between both groups, which might imply the extra growth from long length was due to the fascicle length increases.
- Intense static stretching (to uncomfortable levels), in theory, might tell us how “stretching-based forces” influence muscle growth. In such studies, intense static stretching produces muscle growth, but this seems to likely be due to fascicle length increases and not any pennation angle gains.
- Eccentric-only training (where you lower a load that would otherwise be too heavy to lift) involves muscle lengthening, and so in theory, it might also tell us about how “stretching-based forces” influence muscle growth. Often, eccentric-only training is compared to concentric-only training, and concentric-only training is where you just lift a load, and not lower it. Some of such papers find eccentric-only training produces much larger increases in fascicle length, while pennation angle chances tend to actually be better with concentric-only training.
However, there’s still evidence (also indirect and limited) suggesting the extra growth from training at longer lengths may not just be an increase in sarcomeres in series.
- In this paper, training with a full range of motion (which reaches longer lengths) tended to produce numerically greater pennation angle increases than training with a partial range of motion at short lengths.
- This particular study found intense and long-duration static stretching managed to produced pennation angle increases for the medial gastrocnemius
- This paper found that eccentric-only training caused greater increases in pennation angle (at the lower part of a muscle) compared to concentric-only training.
So there are arguments on both sides, but the evidence is pretty limited and indirect.
Here are some extra thoughts I also would like to share.
Right now, it remains possible longer length training could signal muscle growth through other mechanisms that do lead to an increase in sarcomeres in parallel (such as stretch-activated ion channels or nuclear flattening).
This discussion has also been focused on “hypertrophy”, which is an increase in the size of individual muscle fibers. “Hyperplasia” is an increase in the number of overall muscle fibers. Animal data finds extreme stretching stimuli can cause robust hyperplasia. Whether training muscles at longer lengths causes hyperplasia in humans hasn’t been investigated, and in my mind, it remains a possibility until data suggests otherwise.
I’m also skeptical of the consistency and accuracy of using fascicle length and pennation angle measures. For example, this study measured fasicicle length, pennation angle, and whole muscle cross-sectional area across multiple regions of a muscle. At one of the regions, one group saw greater fascicle length and pennation angle increases, so we’d expect this group to see greater whole muscle cross-sectional area increases. Yet, they didn’t end up seeing greater increases in whole muscle cross-sectional area at this region (rather the gains were similar).
It is also worth noting in humans, increases in fascicle length have yet to be properly validated as reflecting an increase in sarcomeres in series. In fact, the only human study to date (as far as I know) actually found an increase in the length of each sarcomere was probably responsible for the fascicle length increases. However, this study was merely 3 weeks. I think it’s very possible over long durations, an increase in sarcomeres in series would occur. Plus, my personal belief is that an increase in sarcomeres in series likely does happen in humans, and an increase in fascicle length would follow (data on the length-tension of the whole muscle leads me to speculate this, but this is beyond the scope of this article).
At the end of the day, my thoughts are that we simply need better-quality research before we can derive confident conclusions.
REFERENCES FROM THE OVERALL PEC VIDEO
References:
Paper on regions of the pecs: https://pubmed.ncbi.nlm.nih.gov/19291757/
Paton & Brown (EMG on 6 regions of the pecs) – https://pubmed.ncbi.nlm.nih.gov/20870556/
1997 paper on pec leverage – https://pubmed.ncbi.nlm.nih.gov/9356931/
neuromechanical matching paper (leverage relates to recruitment) – https://pubmed.ncbi.nlm.nih.gov/30985474/
Ogasawara (bench pressing and pec growth in untrained) – https://pubmed.ncbi.nlm.nih.gov/23053130/
Davies et al. (bench pressing and pec growth in trained folks) – https://pubmed.ncbi.nlm.nih.gov/35916746/
Machine horizontal pressing research (3)
- https://pubmed.ncbi.nlm.nih.gov/37535335/
- https://journals.lww.com/nsca-jscr/fulltext/2010/03000/a_comparison_of_muscle_activation_between_a_smith.26.aspx
- https://journals.lww.com/nsca-jscr/abstract/1994/11000/a_comparison_of_muscle_activity_between_a_free.11.aspx
- https://www.researchgate.net/publication/335092202_Specific_prime_movers%27_excitation_during_free-weight_bench_press_variations_and_chest_press_machine_in_competitive_bodybuilders
- https://journals.lww.com/nsca-jscr/fulltext/2012/11000/the_sticking_region_in_three_chest_press_exercises.7.aspx
- https://www.researchgate.net/publication/49746305_A_comparison_of_muscle_activity_and_1-RM_strength_of_three_chest-press_exercises_with_different_stability_requirements
- https://journals.lww.com/nsca-jscr/fulltext/2017/07000/maximal_strength_performance_and_muscle_activation.15.aspx
- https://pubmed.ncbi.nlm.nih.gov/37229415/
Dumbbell bench pressing research
- https://journals.lww.com/nsca-jscr/fulltext/2012/11000/the_sticking_region_in_three_chest_press_exercises.7.aspx
- https://www.researchgate.net/publication/49746305_A_comparison_of_muscle_activity_and_1-RM_strength_of_three_chest-press_exercises_with_different_stability_requirements
- https://journals.lww.com/nsca-jscr/fulltext/2017/07000/maximal_strength_performance_and_muscle_activation.15.aspx
- https://journals.lww.com/nsca-jscr/fulltext/2021/02001/relationship_of_barbell_and_dumbbell_repetitions.10.aspx
Push ups vs bench press research
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386139/
- https://www.sciencedirect.com/science/article/pii/S1728869X17301028
- https://pubmed.ncbi.nlm.nih.gov/29466268/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7196742/
- https://pubmed.ncbi.nlm.nih.gov/32774533/
- https://pubmed.ncbi.nlm.nih.gov/25419894/
Plotkin progressive overload: https://pubmed.ncbi.nlm.nih.gov/36199287/
Velocity loss paper: https://pubmed.ncbi.nlm.nih.gov/35728808/
Dumbbell vs barbell vs smith machine fatigue paper: https://journals.lww.com/nsca-jscr/fulltext/2017/01000/chest_press_exercises_with_different_stability.9.aspx
free weight vs machine meta-analyses (2): https://pubmed.ncbi.nlm.nih.gov/37582807/ + https://pubmed.ncbi.nlm.nih.gov/34609100/
3 studies on partial ROM at longer lengths: https://pubmed.ncbi.nlm.nih.gov/33977835/ + https://pubmed.ncbi.nlm.nih.gov/37015016/ + (3rd paper not officially published yet)
isometric data on long lengths: https://onlinelibrary.wiley.com/doi/10.1111/sms.13375
Maeo and pec stretching paper: https://pubmed.ncbi.nlm.nih.gov/33009197/ + https://link.springer.com/article/10.1007/s00421-023-05413-y
Well controlled EMG study: https://pubmed.ncbi.nlm.nih.gov/28943236/
7 papers on incline angles
- https://www.researchgate.net/publication/274010566_Influence_of_bench_angle_on_upper_extremity_muscular_activation_during_bench_press_exercise
- https://journals.lww.com/nsca-jscr/abstract/1995/11000/effects_of_variations_of_the_bench_press_exercise.3.asp
- https://pubmed.ncbi.nlm.nih.gov/31397215/
- https://pubmed.ncbi.nlm.nih.gov/20512064/
- https://pubmed.ncbi.nlm.nih.gov/28713459/
- https://pubmed.ncbi.nlm.nih.gov/33049982/
- https://journal.iusca.org/index.php/Journal/article/view/39
Upper pecs have leverage for shoulder flexion (Ackland): https://pubmed.ncbi.nlm.nih.gov/18691376/
8 closer grip EMG studies
- https://pubmed.ncbi.nlm.nih.gov/34198674/
- https://pubmed.ncbi.nlm.nih.gov/33554113/
- https://pubmed.ncbi.nlm.nih.gov/16095407/
- https://journals.lww.com/nsca-jscr/abstract/1995/11000/effects_of_variations_of_the_bench_press_exercise.3.asp
- https://journal.iusca.org/index.php/Journal/article/view/39
- https://pubmed.ncbi.nlm.nih.gov/37229415/
- https://journals.humankinetics.com/view/journals/ijspp/15/9/article-p1252.xml?alreadyAuthRedirecting
- https://pubmed.ncbi.nlm.nih.gov/33555823/
2 reverse grip EMG studies: https://pubmed.ncbi.nlm.nih.gov/16095407/ + https://journal.iusca.org/index.php/Journal/article/view/39
Decline studies (5 of them in total)
- https://www.researchgate.net/publication/274010566_Influence_of_bench_angle_on_upper_extremity_muscular_activation_during_bench_press_exercise
- https://journals.lww.com/nsca-jscr/abstract/1995/11000/effects_of_variations_of_the_bench_press_exercise.3.asp
- https://pubmed.ncbi.nlm.nih.gov/31397215/
- https://pubmed.ncbi.nlm.nih.gov/28713459/
- https://journal.iusca.org/index.php/Journal/article/view/39
2 dip papers
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9603242/
- https://forums.t-nation.com/t/inside-the-muscles-best-chest-and-triceps-exercises/284620
3 EMG papers on isolation vs compound
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7675616/
- https://journals.lww.com/nsca-jscr/abstract/2005/05000/electromyographic_activity_of_the_pectoralis_major.34.aspx
- https://www.scielo.br/j/rbme/a/wZB7qVqH98pXGzH9p4kyg5Q/?format=pdf&lang=en
Individual differences EMG paper: https://pubmed.ncbi.nlm.nih.gov/32460639/
Grip width and injury risk paper: https://journals.lww.com/nsca-scj/_layouts/15/oaks.journals/downloadpdf.aspx?trckng_src_pg=ArticleViewer&an=00126548-200710000-00001
Two EMG papers on lats and pec activity at different shoulder angles: http://www.aulakinesica.com.ar/semioquirurgica/files/biblio_control_motor04.pdf + https://pubmed.ncbi.nlm.nih.gov/35992501/
One emg paper direct on barbell pullovers: https://www.mdpi.com/2076-3417/12/21/11138
glute max and leverage research: https://pubmed.ncbi.nlm.nih.gov/6390670/ + https://pubmed.ncbi.nlm.nih.gov/27504484/ + https://pubmed.ncbi.nlm.nih.gov/31230110/
Chaves paper: https://pubmed.ncbi.nlm.nih.gov/32922646/
Pump research paper: https://pubmed.ncbi.nlm.nih.gov/36334406/
Wadhi paper on middle and outer region pec growth: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9436038/