©Anthony Lett. Alll rights reserved 2015.
PILATES & REHAB
Reciprocal Inhibition or Innervation (RI) was discovered
by Sir Charles Sherrington in 1947 in the development of a model for how the neuromuscular system works. Reciprocal inhibition is an involuntary biomechanical and physiological process whereby when a muscle contracts, for example the biceps of the arm, RI occurs to inhibit its opposing muscle – the triceps – from contracting also. Without this process, your arm would be locked altogether. Of course we can override this reflex and lock our arm too if we want to hold something overhead for example, in a process called Co-contraction. When we want to brace the spine we will co- contract the abdominal and trunk extensor muscles too. Later in this paper, we will see that RI can decline with age but can be enhanced by the practice of stretching.
How to Use RI when stretching RI can be used in two particular ways when stretching. A– It can be used to produce the movement to get into a stretch, and B, it can be used to reduce the tone of a muscle group during a static stretch. Below are two examples. A) When stretching the hamstrings in our reformer lunge,( Image one) we use the quadriceps to move into the stretch position. In doing so, we use RI to reduce the nerve impulses to the hamstring muscles we are stretching and thereby reduce their resistance to elongation. Cueing becomes ultra-important in this regard, to ensure the correct recruitment of muscle groups so as to facilitate the RI reflex.
How to stretch: image 1
Lower hips maximally and move carriage away using quadriceps, to stretch hamstrings and engage RI reflex. Hips must remain low. Hold the stretch statically for 60 to 90 seconds
Tip: use the cue “press front foot into the floor in a pushing or sliding away motion” to move the carriage away, to ensure the engagement of the quads. NB. In our Innovations in Pilates work, we would then hold the stretch position statically and engage another reflex called the Golgi Tendon Reflex by pressing the front foot down into the floor for short period. This would facilitate an even greater relaxation of the hamstrings. The cue is to pull the heel back toward the bottom, as a bull in a bull fight! See the book Innovations in Pilates –Therapeutic muscle Stretching on the Pilates Reformer for further information.
Example B - Once in a stretch, you can use RI to try to relax the muscles under elongation even further. In
the stretch below, (image two) the hamstrings, glutes and Adductor Magnus are under stretch. To use RI, try contracting and relaxing the quadriceps repeatedly 6 to ten times. Contract them on and off for around one second at a time. You may well find that the intensity of the stretch in the hamstrings is significantly reduced after this. In addition, the effort is useful for neuromuscular education, particularly of the VMO portion of the quads. The VMO is known to stabilize the knee joint and maintain good patella tracking.
image 2
Clinical Applications RI has implications for Clinical Pilates, or any form of corrective exercise. Good posture and alignment is dependent on the balance of muscular forces around our joints. For example, rounded shoulders and a poking chin (known as upper crossed syndrome (see image 3) are the result of an imbalance of forces around the
image 3
shoulder girdle. Most commonly, the upper part of trapezius, levator scapulae, pectoral and biceps muscles are tight and short, while the deep neck flexors and lower scapular stabilizers are inhibited and weak. In correcting such an imbalance we cannot simply strengthen the weak muscles. Why? Because of the RI reflex. In this instance, the tight muscles of the chest are inhibiting the muscles on the other side of the joints, reducing their tone (by reducing the number of nerve impulses reaching the muscles) and preventing their ability to become stronger. This effect, called ‘pseudo paresis’, is a dominant feature of muscle imbalance around joints, and necessitates the stretching of tight muscles before any type of corrective strength procedures can be effective. Leon Chaitow sums it up well in his book titled “Modern Neuromuscular techniques.” ”Clinical experience, and especially therapeutic results, support the assumption that (according to Sherrington’s law of reciprocal inhibition) tight muscles act in an inhibitory on their antagonists. Therefore, it does not seem reasonable to start with strengthening of the weakened muscles, as most exercise programs do, it has been clinically proved that is better to stretch tight muscle first. It is not exceptional that, after stretching of the tight muscles, the strength of the weakened antagonist improve spontaneously, sometimes immediately, sometimes within a few days, without any additional treatment” Chaiton
Jane would then stretch the arm out and put it in a cast for several weeks. The result would be the growth of new muscle fibers called “sarcomeres.” Janes approach demonstrates the two fundamental restrictions to the achievement of full joint range of motion, even in healthy individuals. The first is neuromuscular tone. This is the image that your brain has of the comfortable length of all muscles, which becomes wired into the system. This “wiring” results from learned movement habits and can limit movement despite any real risk of injury. When switched off, with Botox or a general anesthetic for example, or “toned down” with therapeutic stretching, the muscle can be lengthened, and the joint moved further. The second restriction is the actual length of the fibers themselves, or the extensibility of the “meat.” When stretched repeatedly, or held in a lengthened state with a cast, a biological adaptation occurs. Like inserting a few extra links into a chain, more fibers or “meat” are grown.
Pilates “Chest Expansion” (image 4 cortesy of Basi Pilates) is an exercise which strengthens the posterior muscles of the trunk like the rhomboids and mid/lower trapezius to correct the upper crossed syndrome described above. When programming for this correction, given what we know about RI, it makes sense to stretch the anterior chest wall first. Practice a pectoralis major and minor stretch like the one pictured here.
Anecdote supports theory Jane, a student in my Innovations in Pilates teacher training program a few years back told us of similar experiences. In her work as a neurological physiotherapist at a Melbourne hospital, she encountered patients with all manner of contractures. Often, their arms would be locked up and folded across their chests in a constant spasm of the Bicep and other flexor muscles. Jane would inject Botox into the bicep muscles to shut off their ability to contract, and the result would be almost instant re-ignition of their opposing muscles the triceps. This was a dramatic display of RI at work.
1- Place the anterior surface of the arm onto the floor 2- Roll the chest, hips and leg back toward the arm.
image 4
Some recent research Scientific studies have demonstrated that reciprocal inhibition diminishes as we age (and also in certain disease processes). This is particularly important for activities such as walking. For example, if the tibialis anterior does not efficiently inhibit the gastrocnemius/soleus muscles of the calf, the person tends to catch their toes, stumble and fall. If that weren’t bad enough, our bones also weaken with age, so falls can lead to fractures
How Innovations in Pilates can help Recent scientific evidence has shown that stretching can increase reciprocal inhibition between antagonist muscles. For this study, the authors investigated the effect of stretching on reciprocal inhibition between the tibialis anterior and the gastroc/soleus complex. See image on left. They stated: “In conclusion, we have found that 3 week of twice-daily, static plantar flexor stretching resulted in a significant increase in RI, measured in soleus and gastrocnemius during voluntary, tonic dorsiflexion contractions.� (The full article is linked below in the references)
The Studio lesson learnt Teach your clients, particularly the elderly ones, some static stretching. Below (image 5) is a simple stretch for the calf group taken from the Innovations in Pilates series of books. (For more details purchase the book, web details below) Press the carriage away, and slowly lower the heel. Use heavy enough springs to impart a stretch that is around 6 out of ten in terms of intensity. Pad the shoulder rests if the client has bony shoulders or is frail. Hold the stretch for 90 seconds. During the stretch, lift the toes. This will encourage a contraction of the anterior leg muscles and further relax the calves through RI as described above.
image 5
1. A. J. Blazevich , A. D. Kay , C. Waugh , F. Fath , S. Miller , D. Cannavan “Plantarflexor stretch training increases reciprocal inhibition measured during voluntary dorsiflexion” Journal of Neurophysiology Published 1 January 2012 Vol. 107 no. 1, 250-256.
To purchase the book go to WWW.INNOVATIONSINPILATES.COM