Warming Up for Activity: CNS Activation for Injury Prevention

For individuals about to engage in physical activity or exercise, how does warming up the body help prepare for the work ahead?

Central Nervous System Activation

A proper warm-up before physical activity or working out prepares the mind and body to reduce risks of injury, mentally and physically transition to physical activity work, and enhance performance. A well-designed warm-up also primes the central nervous system/CNS for activity. The central nervous system transmits messages to the muscles to prepare them for action. Central nervous system activation increases motor neuron recruitment and engages the sympathetic nervous system so the body can better handle the physical stressors. The process may seem complex, but priming the nervous system is as simple as warming up with light aerobic activity before getting into more explosive movements.

CNS

The CNS consists of the brain and spinal cord. This central communication system uses another part of the nervous system known as the peripheral nervous system or PNS to transmit and receive messages throughout the body. The PNS is connected to the entire body and the brain and spinal cord (CNS).

• Nerves run throughout the body, receiving signals from the CNS to the muscles, fibers, and organs, transmitting various information back to the brain. (Berkeley University. N.D.)
• There are two types of systems within the peripheral nervous system – somatic and autonomic.

1. Somatic nervous system actions are those controlled by the person through voluntary actions like choosing to pick something up.
2. The autonomic system is involuntary and generates actions like breathing or heartbeat. (Cleveland Clinic. 2020)

Properly preparing the body for an intense strength training session or other physical activity needs the correct messages to be sent through the autonomic nervous system.

Parasympathetic and Sympathetic States

The autonomic nervous system consists of two subcategories, which are parasympathetic and sympathetic.

• The sympathetic nervous system helps the body get ready to face stress which includes physical stress. (R. Bankenahally, H. Krovvidi. 2016)
• The fight, flight, or freeze response describes the sympathetic nervous system’s aspect.
• The parasympathetic nervous system is responsible for relaxation and de-stressing.

Individuals are recommended to perform a few calming movements and actions after a workout to return the body to a parasympathetic state. This can be:

• Stretching
• Lying with the legs elevated
• Relaxing yoga poses
• Box breathing
• Taking a warm shower or bath
• Foam rolling
• Massage

Returning the mind and body to a calm state helps with recovery and reduces stress hormone production. (National Academy of Sports Medicine. 2022)

Why Activate the CNS

Activating the CNS can increase performance and prevent injuries. The process wakes up and alerts the body for the activity. Individuals are recommended before beginning a training session, to communicate to the body about the physical stress it is about to endure and to prepare for the work ahead. This is a concept known as post-activation potentiation/PAP. (Anthony J Blazevich, Nicolas Babault. 2019) PAP helps increase force and power production, which enhances physical performance.

• Whenever an individual trains, the brain adapts and learns what the body is doing and the purpose of the training.
• Muscle memory describes this interaction.
• Individuals who have started up a new strength training routine or after an extended break report feeling awkward for the first few sessions, or even weeks, depending on their experience. (David C Hughes, Stian Ellefsen, Keith Baar, 2018)
• However, after a few sessions, the body is more adept at performing the movements and ready to increase resistance, repetitions, or both.
• This has to do with the neural drive and muscle memory than it has to do with true potential physical abilities. (Simon Walker. 2021)
• Training the CNS to be alert and pay attention can increase the development of a healthy mind-muscle connection combined with muscle memory. (David C Hughes, Stian Ellefsen, Keith Baar, 2018)

General Warm-Up

The first step is a general warm-up that should use large muscle groups and be of low intensity so as not to exhaust the body before beginning the actual training. General warm-up benefits central nervous system activation and the entire body include: (Pedro P. Neves, et al., 2021) (D C. Andrade, et al., 2015)

• Increases blood circulation.
• Assists the release of oxygen from hemoglobin and myoglobin.
• Warms the muscles, so they contract more effectively.
• Increases nerve impulse speed.
• Increases nutrient delivery.
• Lowers joints’ resistance through increased synovial fluid/joint lubrication.
• Increases joint range of motion.
• Improves joint resiliency.
• Removes metabolic waste quicker.
• Reduces risk of injury.

A general warm-up can be simple as any aerobic activity will work. This can include:

• Performing bodyweight movements – light jumping jacks or jogging in place.
• Treadmill
• Rowing machine
• Stair climber
• Elliptical trainer

It is recommended to use the rating perceived exertion scale/RPE to determine the general warm-up effort. An exertion rating of between 5 to 6 is equivalent to moderate walking or a slow jog. Individuals should be able to speak clearly without taking a pause.

Try this strategy before the next workout to see increased performance and reduced injury risks.

Ankle Sprains Recovery

References

The nervous system. Berkeley University.

Cleveland Clinic. Nervous system: What it is, types, symptoms.

Bankenahally R, Krovvidi H. (2016) Autonomic nervous system: anatomy, physiology, and relevance in anesthesia and critical care medicine. BJA Education. 16(11):381-387. doi:10.1093/bjaed/mkw011

National Academy of Sports Medicine. Sympathetic vs. parasympathetic overtraining.

Blazevich, A. J., & Babault, N. (2019). Post-activation Potentiation Versus Post-activation Performance Enhancement in Humans: Historical Perspective, Underlying Mechanisms, and Current Issues. Frontiers in physiology, 10, 1359. doi.org/10.3389/fphys.2019.01359

Hughes, D. C., Ellefsen, S., & Baar, K. (2018). Adaptations to Endurance and Strength Training. Cold Spring Harbor perspectives in medicine, 8(6), a029769. doi.org/10.1101/cshperspect.a029769

Walker S. (2021). Evidence of resistance training-induced neural adaptation in older adults. Experimental gerontology, 151, 111408. doi.org/10.1016/j.exger.2021.111408

P. Neves, P., R. Alves, A., A. Marinho, D., & P. Neiva, H. (2021). Warming-Up for Resistance Training and Muscular Performance: A Narrative Review. IntechOpen. doi: 10.5772/intechopen.96075

Andrade, D. C., Henriquez-Olguín, C., Beltrán, A. R., Ramírez, M. A., Labarca, C., Cornejo, M., Álvarez, C., & Ramírez-Campillo, R. (2015). Effects of general, specific, and combined warm-up on explosive muscular performance. Biology of sport, 32(2), 123–128. doi.org/10.5604/20831862.1140426