Stretching (Pt 1)

Love it or hate it, everyone has an opinion when it comes to stretching. Yet we all do it instinctually. Whether it’s the first thing we do in morning when we get out of bed or the last thing we do after being hunched over our desk for hours. The point of contention arises when stretching is done purposefully, as part of a regimen — either before or after an activity, or as a practice all its own. Whether you fall into this latter category or not, there are a few things we should know about stretching before we make up our minds on its efficacy. In this first post on stretching, we’ll be discussing the anatomy of a stretch.

Let’s face it, some people are naturally more flexible than others. Women tend to be more flexible than men. The young are more flexible and limber than their adult counterparts; and there are several reasons for this. As we age, we progressively loose flexibility as part of the normal aging process. Degenerative changes within the muscle and/or joint capsules (arthritis) can lead to an inactive lifestyle. Inactive muscles will adaptively shorten and eventually become weak. Stretching helps to maintain a certain degree of flexibility, which in turn improves our range of motion. Range of motion (ROM) is the degree of movement available for any given body part or joint.

What is stretching?

So what exactly does it mean to stretch? Stretching is the act of placing a specific body part into a position that will lengthen a targeted muscle, muscle group and/or soft tissue structure. Soft tissue structures come in two varieties: contractile and non-contractile. Examples of non-contractile structures include: ligaments, menisci, and joint capsules. This type of soft tissue was designed to provide support and stability. Their primary job is to limit or control the amount of movement across a joint. Other types of non-contractile soft tissue include fascia, skin and scar tissue. Muscle and tendons are the two primary contractile structures. Tendons attach muscle to bone, and by extension only transmit the force of the contracting muscle across a joint to create movement. Since tendons don’t actually contract themselves, that leaves us with muscles as the primary target for stretching.

Every joint in the human body has a range of motion that is considered normal for that joint. Let’s consider the hip as an example. The hip joint has six planes of movement: flexion, extension, adduction (swinging leg across the opposite leg), abduction (swinging leg away from the opposite leg), medial rotation (rotating leg so knee is pointing towards opposite leg) and lateral rotation (rotating leg so knee is pointing away from opposite leg). For each given movement there is a degree or range, which is considered normal.

Range of Motion Available at the Hip:

Flexion: w/extended knee = 80-90 deg, (w/flexed knee = 110-120 deg)

Extension: 10-15 deg

Adduction: 30 deg

Abduction: 30-50 deg

Medial Rotation: 30-40 deg

Lateral Rotation: 40-60 deg

Some people will fall below this range, others slightly above it. Hip flexion (w/an extended knee) for example tends to be the most limited movement of the hip for most people. Think of bending over to touch your toes. If you have trouble doing this, chances are tight hamstrings, as well as tight gluteal and calf muscles are contributing to this limitation. Those who have suffered an injury or lead a sedentary lifestyle might find themselves in this category.

Stretching can be done actively or passively with the help of an aid or an assistant. Depending on the joint where the stretch is performed, you can see a noticeable difference in the amount of passive ROM available. The neck is perfect example. You can yield a greater amount of ROM at the cervical spine if it’s done passively. This is not always the case for every joint however. The hip joint generally yields the same amount of ROM whether it’s done actively or passively.

Tight, short, stiff muscles have a tendency to limit this normal range of motion, as well as contributing to some other issues, such as:

– Chronic muscle and joint pain due to constant tension

– Interference of proper muscle functioning

– A loss of strength and power

– Restrict blood flow and circulation

– Increased muscle fatigue

– Muscle strain or injury

What happens during a stretch?

Muscles are comprised of thousands of tiny cylindrical cells called muscle fibers. Each muscle fiber contains thousand of ‘threads’ called myofibrils. These myofibrils are what give muscles their capacity to contract, relax and lengthen. Within each myofibril are millions of bands of sarcomeres. Sarcomeres are made up of thick and thin myofilaments containing contractile proteins called actin & myosin. When sarcomeres are regularly stretched to their end point, the number of sarcomeres increase and are added to the ends of existing myofibrils. This is what increases the muscle’s length and ROM.

There are two primary reflexes that are engaged when you do a stretch: the “stretch/ myostatic reflex” and the “golgi tendon reflex”.

Stretch/Mysotatic Reflex: During the first few seconds of a stretch (6-10 seconds), tiny proprioceptive cells called muscle spindle organs (MSOs) are activated. MSOs located in the belly of the muscle contract in order to protect the muscle. Their primary function is to detect changes in the length and speed of the stretch and contract accordingly.

Golgi Tendon Reflex: After the first few seconds of a stretch, another set of proprioceptive cells called golgi tendon organs (GTOs) are engaged. Located near the tendons of a muscle, GTOs detect the amount of tension being exerted over a joint and automatically stop contracting in order to protect the muscle from being overloaded.

Knowing about these reflexes can help us to stretch in a much more effective and safe way. Here are two keep points to remember when stretching:

1. Move slowly into the stretch: In order to mitigate the effects of the stretch reflex, it’s important to move slowly into the stretch and only to the point of comfortable resistance. If you move too quickly or stretch to the point of pain, you will activate the stretch reflex and create resistance within the muscle.

2. Hold the stretch for  at least 10 seconds: After this initial period, the MSOs will cease firing and the GTOs will kick in. GTO activity will create inhibition in the muscle, allowing you to stretch further to a new end point.

In part 2 on stretching, we’ll discuss several different types of stretches, the benefits of stretching, and more pointers on how to stretch safely and effectively.