Pandiculation:
Nature's way of maintaining the functional
integrity of the myofascial system?
Luiz Fernando
Bertolucci
Brazil
Abstract
Pandiculation is the involuntary stretching
of the soft tissues, which occurs in most animal
species and is associated with transitions
between cyclic biological behaviors, especially
the sleep-wake rhythm (Walusinski, 2006).
Yawning is considered a special case of
pandiculation that affects the musculature of
the mouth, respiratory system and upper spine
(Baenninger, 1997). When, as often happens,
yawning occurs simultaneously with pandiculation
in other body regions (Bertolini and Gessa,
1981; Lehmann, 1979; Urba-Holmgren et al., 1977)
the combined behavior is referred to as the
stretch-yawning syndrome (SYS).
SYS has been associated with the arousal
function, as it seems to reset the central
nervous system to the waking state after a
period of sleep and prepare the animal to
respond to environmental stimuli (Walusinski,
2006). This paper explores the hypothesis that
the SYS might also have an auto-regulatory role
regarding the locomotor system: to maintain the
animal's ability to express coordinated and
integrated movement by regularly restoring and
resetting the structural and functional
equilibrium of the myofascial system. It is now
recognized that the myofascial system is
integrative, linking body parts, as the force of
a muscle is transmitted via the fascial
structures well beyond the tendonous attachments
of the muscle itself (Huijing and Jaspers,
2005).
It is argued here that pandiculation might
preserve the integrative role of the myofascial
system by (a) developing and maintaining
appropriate physiological fascial
interconnections and (b) modulating the
pre-stress state of the myofascial system by
regularly activating the tonic musculature. The
ideas presented here initially arose from
clinical observations during the practice of a
manual therapy called Muscular Repositioning
(MR) (Bertolucci, 2008; Bertolucci and Kozasa,
2010a; Bertolucci, 2010b). These observations
were supplemented by a review of the literature
on the subject. A possible link between MR and
SYS is presented: The neural reflexes
characteristically evoked through MR are
reminiscent of SYS, which both suggests that MR
might stimulate parts of the SYS reaction, and
also points to one of MR's possible mechanisms
of action.
Yawning for an auto-regulatory role
regarding the locomotor system
For Bertolucci, "pandiculation seems to be
elicited by complex array or sequence of
stimuli, which might include both exteroceptive
signals (eg. light-darkness) and interoceptive
ones (eg.,circadian endocrine cycles and somatic
interoception). Yawning is a series of
coordinated actions that unfold sequentially,
building up soft tissue contractile tension to a
peak, at which point the joints of the limbs and
trunk are maximally extended e or,
alternatively, the trunk is arched in flexion.
After the peak, the soft tissue tension level
plummets, yielding a sense of pleasure and
well-being. The actions can be regional or
involve the whole body, and are often
bilaterally symmetrical".
Le système musculo-squelettique est
en constant remodelage en fonction des
contraintes mécaniques qu'il subit.
Ainsi, l'immobilisation prolongée
entraîne une fonte musculaire et une
déminéralisation du squelette.
Bertolucci argues that "pandiculation with its
specific and vigorous muscle activity, might be
a means to compensate for the mechanical signals
delivered by rest periods and sub-optimal
movements".
Yawning might be considered a feedback from
stiffness, and possibly be triggered by extended
periods of immobility in asymmetrical positions.
If the body tends to stiffen, pandiculation "can
serve to restore the limb (and related
musculature) to an original (homeostatic)
state". [...] " The patterns of
pandiculation are automatic. Through intense and
involuntary deep muscle cocontractions, the soft
tissues actively elongate themselves against the
bony structures as the joints are stiffened.
Each movement within the pattern emerges in
sequence, apparently from the recruitment of a
mosaic of reflexes, the sequence of which can
neither be anticipated nor purposely performed.
Just as a spontaneous yawn feels quite different
from a deliberate imitation of one, spontaneous
pandiculation feels quite different from a
voluntary pandiculation-like stretch. Because
the voluntary and emotional motor systems have
discrete neural pathways, pandiculation's
distinctive internal sensations might be
attributable to the motor unit recruitment
sequences dedicated to automatic movement
patterns". [...]
The importance of stretching to the
maintenance of musculoskeletal health is
well-known. In humans, each of the myriad of
physical fitness regimens that include
stretching has its own rationale; and although
all muscle groups should be stretched, different
regimens address particular problems and are
intended to compensate for various patterns of
muscle shortness or consequent joint mobility
restriction. But how do animals in the wild
maintain musculoskeletal health? They perform no
voluntary stretching and still maintain their
motor capabilities". [...]
The mechanical balance between hard and soft
tissues dictates stress distribution, which
plays a key role in cell shape and metabolism.
In pandiculation, the intense mechanical stimuli
produced by forceful co-contraction of
antagonist muscle groups might serve as
appropriate organizing signals to the cells and
tissues by re-optimizing the mechanical
conditions of their environment". Pandiculation
"might be a biological compensation for periods
of immobility and/or vicious body positions,
restoring the animal's mobility by breaking up
abnormal muscles metabolism cross-links formed
by inactivity or suboptimal activity".
[...]
"Perhaps the vigorous co-contractions of
pandiculation systematically reshape the
structural linkage among segments and
simultaneously signal the cells (via
mechanotransduction) to synthesize the cellular
muscles components required to maintain the
appropriate environment. If so, pandiculation
might help restore optimal musculoskeletal
arrangements, and thus optimize motor
capabilities".
