Full ROM is associated with
significant greater strength and hypertrophy gains than a shorter ROM. One
study found for full ROM a greater increase in strength (18% vs. 4%) and
a greater increase in hypertrophy (60 vs. 15%) at the distal
cross-sectional area closest to the joints (knee or elbow), or insertions (1).
The average hypertrophy across the full length of the muscle belly was
more than double for the full ROM (44% vs. 21%). Also muscle fiber pennation
angles (fiber directions) increased more with full ROM (11% vs. 7% but not
statistically significant).
However shorter ROM can in some instances still produce
significant hypertrophy to the same extent as full ROM (2), persons with
injuries or diminished ROM may benefit from this.
Muscle fibers don’t just span
from origin to insertion, that an over-simplistic way to put it. Jose Antonio
did a review on the Non-Uniform Muscle Growth and regional adaptation
in skeletal muscle (3). Skeletal muscle is a heterogeneous tissue that exhibits
numerous inter- and intramuscular differences: architecture, fiber
composition, and muscle function (3).
With different exercises selective
recruitment of different regions of a muscle can be achieved, so that
there’s no single exercise that can maximize the hypertrophic response of
all regions of a particular muscle (3). Several muscles are
compartmentalized so that fibers terminate intrafascicularly (within the
fascicle) and each subdivision is in turn innervated by its own nerve branch
with different motor unit territories.
A few examples:
Schoenfeld et al (4) investigated
muscle activation for two hamstrings exercises: the stiff leg deadlift
and the lying leg curl. Activation of the upper hamstrings was similar between
exercises, but the activation of the lower hamstrings, both medially and
laterally, was significantly greater in the lying leg curl (170% and 65%
respectively).
In one study, researchers went
on to examine and confirmed the regional difference in muscle
hypertrophy (MRI) corresponding to the regional difference in muscle
activation (EMG) in a multijoint exercise for triceps (5). The area of the
triceps with the most muscle activation had more hypertrophy after 12 weeks.
Also for this case the areas closest to the elbow (distal cross-sectional area)
grew the most as opposed to the area closer to the shoulder (6).
The same authors in other
study correlated muscle activation (MR) for elbow extensors after
one training session for one group with the hypertrophy from another
group performing 12 weeks of training. Significantly lower activation in the
distal region which was correlated with significantly less hypertrophy in the
distal region compared with other areas (6).
For maximal hypertrophy of an
entire muscle various exercises must be executed to purportedly stimulate
growth in a regional- specific manner. In other words, exercise selection
and variety is necessary.
Would you like to know more?
References:
1. McMahon GE, Morse CI, Burden A, Winwood K, Onambélé GL. Impact of range of motion during ecologically valid resistance training protocols on muscle size, subcutaneous fat, and strength. J Strength Cond Res. 2014 Jan;28(1):245-5
2. Pinto RS, Gomes N, Radaelli R, et al. Effect of range of motion on
muscle strength and thickness. J Strength Cond Res 2012; 26(8): 2140-5.
3. Antonio, J. Nonuniform response
of skeletal muscle to heavy resistance training: can bodybuilders induce
regional muscle hypertrophy? J. Strength Cond. Res. 14(1):102–113. 2000
4. Schoenfeld BJ, Contreras B,
Tiryaki-Sonmez G, Wilson JM, Kolber MJ, Peterson MD. Regional Differences in
Muscle Activation During Hamstrings Exercise. J Strength Cond Res. 2014 Jun 24.
5. Wakahara T, Fukutani A,
Kawakami Y, Yanai T. Nonuniform muscle hypertrophy: its relation to muscle
activation in training session. Med Sci Sports Exerc. 2013 Nov;45(11):2158-65
6. Taku Wakahara,
Naokazu Miyamoto, Norihide Sugisaki, Koichiro Murata,
Hiroaki Kanehisa, Yasuo Kawakami, Tetsuo Fukunaga, Toshimasa
Yanai. Association between regional differences in muscle activation in one
session of resistance exercise and in muscle hypertrophy after resistance
training. European Journal of Applied Physiology April 2012,
Volume 112, Issue 4, pp 1569-1576
