We all have our own reasons for trail running and no matter what those reasons may be most of us would like to improve, to be faster, to run longer distances, to recover more quickly. In this series of articles my aim is to share with you, in simple terms, some of the processes that are taking place within our bodies, what the implications of these processes are on our performance and how we can train intentionally to improve various aspects of our physiology and in turn, improve our running performance. In this article I’m going to focus on the Nervous System.
What is the Nervous System?
We have 2 principal communications systems within our bodies, the endocrine system which produces hormones (we will focus on this in a future article) and the nervous system. The nervous system can be broken down into 2 parts, the Central Nervous System (CNS) which includes the brain and spinal cord and the Peripheral Nervous System (PNS), which contains all of the nerves outside of the CNS.
The CNS is the control centre of your nervous system. It controls all physical activity and processes all sensory feedback. It is made up of around 85 billion neurons (nerve cells) in our brains and another billion our spines. Motor neurons in the CNS send messages along axons (nerve fibres) to the muscles in our bodies where the neurons trigger contraction and relaxation which in turn enables movement to take place. In the opposite direction, sensory neurons relay stimuli detected by your senses throughout our bodies via the PNS back to the CNS.
What does it have to do with running?
With any physical activity our bodies must learn the movement patterns required for the task through deliberate practise, running is no different. Think back to the first time you tried to ride a bicycle without stabilisers, your body didn’t have the balance, coordination, control or movement pattern required to perform the task but through deliberate practise it becomes automatic. Now when you ride a bicycle you don’t think about it, everything happens automatically. Running is the same, it’s a learned pattern of movement. If you’re reading this article the chances are that you can already run, your body knows the movement patterns required for the task but can we improve it? Can we make it operate better, faster, more efficiently? The answer is most definitely yes. Through deliberate practise and specific training we can in effect rewire our nervous system in the following 5 areas
Motor unit recruitment and coordination
Any movement begins when we “tell” our body to move. The message comes from the brain, travels to motor neurons in the spinal cord and is then transmitted along the motor neurons’ axons to the muscles. Each motor neuron controls a specific group of muscle fibres within a single muscle. Together, the neuron and the fibres it controls are called a motor unit. Your CNS recruits groups of motor units within a muscle so that they can work together to contract the muscle. When contraction occurs, two mechanisms govern the force of that contraction:
We use both rate coding and recruitment when we run, we generate force by increasing the rate of impulses and by recruiting larger motor units, both are trainable.
Some of the other factors to consider when talking about muscle fibre recruitment are recruitment patterns, reduced inhibition, strength gains and contraction velocity.
Running requires coordinated contraction and relaxation of multiple muscle groups across multiple joints all at the same time. Through many hours of repeated, deliberate practise our nervous system learns and develops new pathways to make this process as efficient as possible. These pathways become hardwired as Recruitment Patterns.
When 1 muscle or muscle group contracts, it’s opposing muscle or muscle group must relax. For example, when our quadriceps contract, the hamstrings must relax. Untrained and undertrained muscles have difficulty coordinating this process efficiently. Training and deliberate practise make this process much more efficient and results in Reduced Inhibition.
When you begin any new strength programme almost all of the early Strength Gains will come from increased nerve recruitment rather than muscle growth. Even if you only train 1 side of your body (which I don’t recommend) the other side of your body will also have some increase in strength just through your body applying what the nervous system has learned on the opposite side of the body.
By performing the correct movement patterns required for running many thousands of times through deliberate practise we can increase the Contraction Velocity of our muscle fibres. Contraction velocity measures the time taken for muscle fibres to reach peak contraction. The faster the contraction velocity the more power we can generate which in turn allows us to run more quickly.
Balance is what keeps us upright (most of the time) when we run. When we run we must push off from one foot, stay upright, recruit multiple muscle groups all at the right time to maintain stability, land on the opposite foot, control the landing forces to stay upright again and repeat the process many thousands of times. As trail runners we are doing all of this while on uneven terrain. If we get this process wrong, for example on a technical downhill at speed, the results can be catastrophic. Fortunately balance is easily improved with specific training.
Proprioception is your body’s awareness of it’s position relative to it’s surroundings and it’s ability to adjust to those surroundings accordingly. The classic example for trail runners is when we step on a loose rock or uneven ground and our foot/ankle must react quickly and automatically to prevent an ankle sprain. This automatic response can be trained by deliberately training in an unstable environment and creating those automatic recruitment patterns that prevent the ankle from rolling.
Our proprioceptive system includes the inner ear and nerves connecting the CNS to the muscles, tendons and ligaments. The nerves relay position, tension and stretch sensations to the CNS. The CNS responds by triggering muscle contractions that hold or alter your bodies position, whichever is required.
A common example of proprioception training is the wobble board, a “controlled” unstable environment.
Nervous System Fatigue
We cannot learn new movement patterns or skills when the nervous system is fatigued. Fatigue prevents the CNS from delivering the brain’s orders to the muscles and prevents our PNS from reporting back to the brain effectively. Ultimately we can’t beat nervous system fatigue but we can learn what causes it and plan our training effectively to avoid it.
The most common causes of nervous system fatigue are short, high intensity exercises. The closer to 100% effort that we train the higher the stress on our nervous system. This is true for both running intervals and lifting weights. We need to ensure sufficient recovery betweens sets and overall workouts.
Symptoms of nervous system fatigue include trembling hands, clumsiness, difficulty sleeping, difficulty concentrating and reduced grip strength. If you recognise these symptoms in yourself then dial back the hard workouts and allow your body to recover.
I discussed running economy in the first article in this series. It is the measure of how efficiently we use oxygen at a given speed. When we consider some of the factors that contribute to improved running economy, weekly mileage, tempo running, race pace intervals, high intensity intervals, resistance training, plyometrics it’s easy to see why targeted nervous system training is so important in our development as athletes. A highly functioning, efficient nervous system has a huge role to play in every one of those contributing factors.
How can we incorporate nervous system training into our programme?
To develop the nervous system our training programme should include the following:
If you would like to know more about how to focus your training to improve nervous system function then please drop me an email at email@example.com