Skeletal muscles move the body, they contract and generate movement. But muscles aren't just there for doing exercise. In addition to movement, muscles can also work to support posture, stabilise joints, and produce heat.
The anatomy of skeletal muscle:
Each muscle is an organ consisting of various other tissues including blood vessels, connective tissue, nerve fibres, and muscle fibres.
Each muscle is wrapped in a dense connective tissue called the epimysium which allows the muscle to move and contract whilst maintaining its structural integrity and keeping it separate from other structures so that it can move independently.
Inside the muscle, the fibres are arranged into bundles, called fascicles these bundles are also separated by connective tissue called the perimysium. The collagen within the muscle connective tissue connects with the collagen of the tendon, which connects the muscle to the bone. In other places, the muscle may connect to a broad tendon-like sheet called aponeurosis or to fascia.
Each fascicle consists of bundles of muscle fibres, and inside each fibre are chains of myofibrils, which are rod-like organelles of the muscle cells. The contractile unit of these fibres is the sarcomere, the sarcomere is composed of two main protein filaments (thin actin and thick myosin). These are the active structures responsible for muscle contraction as they slide past one another and increase the overlap, resulting in muscle shortening and, therefore contraction.
Types of muscle fibres:
Skeletal muscle fibres can be classified based on two categories a: how fast they can contract relative to others and b: how the fibres regenerate ATP. Different muscles will be composed of different percentages of muscle fibre types depending on their function in the body.
Type 1 (Slow Oxidative): These fibres contract relatively slowly and utilise aerobic respiration to produce ATP. Type 1 muscle fibres are slow to fatigue because they produce lower power contractions over longer periods. Therefore, they aid in supporting posture and stabilising joints.
Type 2a (Fast Oxidative): These fibres produce faster contractions than Type 1. They can also utilise a combination of aerobic and anaerobic respiration to generate ATP. Type 2a fibres are primarily utilised for movements such as walking, that require more contraction than postural control but less than explosive movements.
Type 2b (Fast Glycolytic): These fibres produce fast contractions and primarily use anaerobic glycolysis. These fibres will fatigue faster than the others however, they are capable of producing rapid, powerful, and explosive movements because they can generate ATP much faster, therefore they cannot be used for long periods.
Types of skeletal muscle contraction:
Isometric:
An isometric muscle contraction occurs when the sarcomeres produce force but the length of the muscle remains the same. This type of contraction helps to regulate posture and transfer forces across joints. In relation to physiotherapy, these contractions can help to build strength, although not as effectively as the other contractions, exercises involving isometric contractions can often be performed anywhere, standing still, with any level of fitness, and during the early stages of rehabilitation.
Concentric:
A concentric muscle contraction causes a shortening of the muscle fibres, often counteracting a load whilst generating force. This type of contraction is effective at building muscle mass, although alone it will not effectively produce strength unless used in conjunction with other contraction types.
Eccentric:
Eccentric muscle contraction occurs when there is elongation of the muscle, but it still generates force. There is increasing interest in employing this type of muscle contraction for rehabilitation and clinical purposes. However, unaccustomed eccentric contractions are more likely to cause injury and delayed onset muscle soreness (DOMS).
What does this mean for veterinary physiotherapy and my animal?
When prescribing and undertaking physiotherapeutic exercises from a therapist we are able to target the different muscle fibre types with different contractions to achieve various effects. Whether this be isometric contractions, such as equine belly lifts, which will primarily target postural stabilisation. Or concentric and eccentric contraction through pole work and transitions to build muscle mass and strength, we can produce various effects to help the individual animal, and the state of their tissues.
But it's not always increasing strength, and understanding muscle anatomy and location is also imperative to ensure massage techniques can correctly target the muscles, increasing the effectiveness of the treatment.
Ultimately, the muscular system plays a huge role in injury, rehabilitation, and performance of our animals. By influencing it through manual therapy and remedial exercise we can improve healing, support, comfort, performance, and quality of life of our pets.
If you feel your animal could benefit from a physiotherapy session or you have any questions. Please don't hesitate to contact us on:
Email: info@arcvetphysio.co.uk
Tel: 07527310689
Facebook: ARC Veterinary Physiotherapy
Instagram: @arcvetphysio
Comments