BAREFOOT TRAINING: the fundamentals of human movement
Part 2: RELAX TO CONTRACT
The initial sequence of bipedal locomotion – where the foot and the ankle reciprocally roll outward toward the pinky toe – is called supination. And given the cyclic, sequential nature of locomotion, it is closely bound up with the landing phase of walking, running, or jumping. Furthermore, this sequence of downward motions may come naturally with an exhalation that starts from diaphragmatic relaxation.
The diaphragm is a thin muscle underneath the lungs (located within the rib cage, not in the abdominal cavity) whose contractions and relaxations initially cause the lungs to inflate and deflate, making it a major respiratory muscle, closely working with abdominal muscles and corresponding to their changes in the degree of intensity of contractions, etc. So, in the simplest sense, we breathe out as the diaphragm relaxes and recoils – shortening to its resting shape, yet moving upward, pushing the air out of the lungs. And as the lungs become deflated, abdominal muscles are relaxed to some extent, or vice versa – either way, it creates downward momentum – the exact opposite occurs when we breathe in.
And while performing intense movements like sprinting, jumping, kicking, etc., the body releases more energy in response to higher demands and thus consumes more of it than resting or doing moderate activities. Yet, the energy for the cells in our body – generated either aerobically or anaerobically – is accompanied by by-products to be expelled: carbon dioxide: more commonly, Co2. So to expel the amount of Co2 – produced while performing intense movements – the diaphragm needs to be further relaxed and even contracted (lengthened, pulled upward more than usual). And for that, we exhale – mostly unconsciously – faster, deeper, sharper, and longer. Furthermore, this forceful process – a series of expiratory contractions initiated by diaphragmatic relaxation – can be performed voluntarily when needed. By extension, it is also possible to enhance the ability to adjust the level of intensity of exhalation. And given the cyclic, complementary nature of respiration, what can be enhanced by doing so is the ability to control breathing rhythms: the most underrated element, which virtually affects every element contributing to bodily movements and thus is vital for force generation, postural control, performance efficiency, etc.
Vertical oscillation – largely driven by respiration, a continuous cycle of inspiration and expiration, facilitated by a series of contractions and relaxations, mostly starting from the abdomen – is another key feature of bipedal locomotion. As discussed above, the downward phase of respiration is – in a very mechanical sense – initially caused by diaphragmatic relaxation – from which the abdomen becomes relaxed to the extent that the trunk tilts slightly forward and downward. In contrast to downward momentum, which comes with exhalation and expiratory contractions, the upward phase is closely related to a series of muscle contractions that causes inhalation. So given the cyclic, sequential nature of respiration, this very physical process of filling the lungs with air can be performed better – or done more smoothly – with the lungs properly deflated, the diaphragm properly relaxed (or shortened when forced), and muscles (from pelvic floors, through the abdomen and back, to the neck and face) properly relaxed.
By extension, a neutral posture may refer to a body position where respiratory flows (expressed by vertical oscillation) are least obstructed – in which abdominal muscles can relax and contract freely enough, corresponding to a cyclic sequence of diaphragmatic relaxation and contraction. More specifically, it refers to a subtle quality of a posture that can be taken in various stances and positions – in which two factors matter most: respiratory flows (not to be disturbed for normal functioning) and readiness for subsequent movements (to be performed from a given posture).
However, the notion of neutrality in posture may sound obscure, but it isn’t that difficult to understand and apply in practice. For example, while maintaining an upright-standing position – with a chin held exceedingly high, the lumbar spine nearly fully extended (curved in), the chest puffed up, and the hips tightly squeezed – it may not be easy to relax and exhale. And responding to an unexpected stimulus from this posture may not be easy either. So regarding the neutrality in posture, excessive tensions may need to be addressed. But still, it is not impossible to walk, run, or even jump while maintaining this posture that is heavily dependent on prolonged contractions. Yet, it is functionally inefficient and less responsive, particularly when compared to a crouched posture – with the neck relaxed, the trunk leaning forward, and the knees and ankles bent – typically shown in a starting position in many sports, such as running and swimming: extensive forms of locomotion. From this characteristic position, where the body can remain relaxed to some degree, the subsequent movement can easily begin with the breath (either inhalation or exhalation) that initiates a rapid series of contractions of abdominal muscles (expiratory contractions in the case of exhalation, as discussed above). But for optimal performance, a certain amount of muscular tension should be maintained – slightly leaning forward, not slumping, not too loose – from which the body gets ready for action.
To put all of those into context, the very nature of bodily movements is cyclic, sequential, and complementary: bodily movements are, from a functional standpoint, all connected and inseparable. So speaking of the pinky toe, it is not only about supination nor landing; it is down there to facilitate a subsequent movement: pronation – the foot and the ankle, reciprocally rolling inward toward the big toe, the last one that touches the ground.
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