Mechanical tension seems to be the primary drive for
the hypertrophic response (1,2). Mechanical forces are converted into chemical
signals in a process called mechanotransduction. This causes molecular
and cellular responses in myofibers and satellite cells (3), and mechanical
stress alone can directly stimulate mTOR (initiation of protein synthesis) (4,5).
A muscle
does not know what it contracts against; it just contracts or relaxes (6).
Training to failure, recruiting as many motor
units as possible seems optimal (7). This Intensity of effort is perhaps
the single most influential controllable variable for enhancing muscular
strength, however untrained subjects have a diminished ability to recruit
motor units (8).
The recruitment of motor units and muscle fibers
stimulates muscular growth irrespective of what has caused that recruitment.
This can be achieved with higher or lower loads and respectively lower or
higher repetitions (8). Lighter loads lifted to the point of failure
result in a similar amount of muscle fiber activation compared with
heavier loads, and both fiber types are stimulated to a roughly equivalent
extent (10,11).
There appears to be no difference in the hypertrophic
response so long as fatigue is induced. In fifting heavy or lighter
loads there’s roughly equivalent hypertrophy and strength gains
(9,-17).
- One study compared 80%RM vs 30%RM sets to failure
with no significant differences between groups for “recreationally active
subjects” (10);
- Another compared 3 sets with 75%RM to 4 sets with
30%RM to “volitional fatigue”, again with similar increases in muscle
cross-sectional area for untrained subjects (11);
- 3–5 vs. 20–28 of repetitions for each exercise,
“until fatigue” with approximately equal volume, also showed no differences for
“physically active” subjects (12);
- Lower loads, when combined with vascular occlusion,
promote equivalent hypertrophy than heavier loads with the same number of sets
and similar volume: 50%-30%RM vs. 80%-50%RM “until failure” for “relatively well-trained
subjects” (14) and 50%RM vs. 80%RM “to exhaustion” in untrained subjects
(15);
- In another study by Schoenfeld et al. (16) comparing
powerlifting style training (low reps, higher loads) versus hypertrophy style
(higher reps and moderate loads), this time with equalized volume and
also to momentary muscular failure, there was no difference in the hypertrophy
magnitude after 8 weeks for “well-trained men”.
(Note: untrained subject will respond well to any
stimulus, just like obese subjects will respond well to any diet, however note
that the same trend is found in trained subjects, otherwise it would be
irrelevant.)
However lifting moderate loads for moderate
repetitions is less taxing to the nervous system, joints, and is time efficient
compared to higher loads and low repetition ranges, subjects from the
hypertrophy group could do more volume if necessary (16).
Training to failure could sometimes lead to overuse
injuries (18,19) and for some people could even reduce the levels of IGF-1
hormones responsible for muscle growth after at least 11 weeks (20).
So in short, if momentary failure is achieved
it doesn’t matter how many reps are performed and under what load.
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References:
1. Goldberg AL,
Etlinger JD, Goldspink DF, et al. Mechanism of work-induced hypertrophy of
skeletal muscle. Med Sci Sports. 1975 Fall;7(3):185–98.
2. Jones, DA
and Rutherford, OM. Human muscle strength training: The effects of three
different regimens and the nature of the resultant changes. J
Physiol 391: 1–11, 1987.
3. Toigo M,
Boutellier U. New fundamental resistance exercise determinants of molecular and
cellular muscle adaptations. Eur J Appl Physiol 97: 643–663, 2006.
4. Hornberger
TA, Chu WK, Mak YW, et al. The role of phospholipase D and phosphatidic acid in
the mechanical activation of mTOR signaling in skeletal muscle. Proc Natl Acad
Sci USA. 2006;103(12):4741–6.
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Meador BM, Johnson B, Huntsman HD, Mahmassani Z, Valero MC, Huey KA, and
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following multiple bouts of eccentric exercise. J Appl Physiol 111:
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6. Fisher J,
Steele J, Bruce-Low S, Smith D. Evidence-Based Resistance Training
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JM. The application of training to failure in periodized multiple-set
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8. Fisher J,
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RM. Impairment of neuromuscular propagation during human fatiguing
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10. Mitchell CJ, Churchward-Venne TA, West DW,
Burd NA, Breen L, Baker SK, Phillips SM. Resistance exercise load does
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11. Ogasawara
R, Loenneke JP, Thiebaud RS, and Abe T. Low-load bench press training to
fatigue results in muscle hypertrophy similar to high-load bench press
training. International Journal of Clinical Medicine 4: 114–121, 2013.
12. Leger B, Cartoni R, Praz M, Lamon S, Deriaz
O, Crettenand A, Gobelet C, Rohmer P, Konzelmann M, Luthi F, Russell AP. Akt
signalling through GSK-3beta, mTOR and Foxo1 is involved in human skeletal
muscle hypertrophy and atrophy. J Physiol 576: 923–933, 2006.
13. Takarada Y, Sato Y, Ishii N. Effects
of resistance exercise combined with vascular occlusion on muscle function in
athletes. Eur J Appl Physiol 86: 308–314, 2002.
14. Takarada Y, Takazawa H, Sato Y, Takebayashi
S, Tanaka Y, Ishii N. Effects of resistance exercise combined with
moderate vascular occlusion on muscular function in humans. J Appl Physiol 88:
2097–2106, 2000.
15. Tanimoto M, Ishii N. Effects of
low-intensity resistance exercise with slow movement and tonic force generation
on muscular function in youngmen. J Appl Physiol 100: 1150–1157, 2006.
16. Schoenfeld BJ, Ratamess NA, Peterson MD, Contreras B,
Sonmez GT, Alvar BA. Effects of different volume-equated resistance
training loading strategies on muscular adaptations in well-trained men. J
Strength Cond Res. 2014 Oct;28(10):2909-18
17. Ogasawara
R, Yasuda T, Sakamaki M, et al. Effects of periodic and continued resistance
training on muscle CSA and strength in previously untrained men. Clin Physiol
Funct Imaging 2011; 31: 399-404.
18. Willardson
JM. The application of training to failure in periodized multiple-set
resistance exercise programs. J Strength Cond Res. 2007 May;21(2):628-31.
19. Ivan Chulvi
Medrano. Muscular
failure training in conditioning neuromuscular programs. Journal of Human Sport &
Exercise Vol. V No II 2010 19 6-213
20. MikelIzquierdoJavierIbañezJuan JoséGonzález-Badillo. Differential effects of strength
training leading to failure versus not to failure on hormonal responses,
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