Tag Archives: Post activation potentiation

Core Before or Core After?

I was recently asked by a colleague: Why does NASM recommend performing core exercises prior to SAQ and resistance exercises when most other organizations state to perform core at the end? It is a long-winded, highly-debatable question, so I decided to write a short blog on the topic providing my thoughts.

The theory of performing core exercise at the end of training is very valid and certainly has utility.The primary theory to performing core exercise after resistance training is fatigue. Resistance, reactive and SAQ training targets our prime movers which are predominately made of Fast Gylcolytic (FG) and Fast Oxidative Glycolytic (FOG) muscle fibers. These fibers are easily fatigued due to their avascular properties. Core musculature is rich in Slow Oxidative (SO) muscle fibers. High vascularity makes SO fibers resistant to fatigue secondary to the accessibility to oxygen.

A common fault with core training technique is allowing the prime movers – saturated with FG / FOG fibers – to dominate the SO dominant muscle fibers of the core. Subsequently, we are not properly working the core muscles, we are just training our prime movers to act as core stabilizers. During higher intensity exercise like SAQ, reactive, and resistance training the FG and FOG muscle fibers become fatigued. Thus, when we transition to core exercises, the fatigued prime movers are less likely to become dominant and will allow for the core musculature and SO dominant muscles to do there job. So the organizations that support this method are certainly not wrong.

Conversely, NASM has a completely different outlook on when to perform core exercises. By performing core exercise after flexibility and prior to SAQ, plyometric, or resistance exercise serves as a functional warm-up to stimulate the neuromuscular system and enhance neuromuscular efficiency during more intense exercise. By doing so, our neuromuscular system is prepared and ready for higher intensity exercise and can prevent unwanted motion of joints and prevent injury.

The thought process behind this is the increased neurological stimulation that occurs when performing core exercise. This increased neural stimulation is much like the neural response that occurs with post-activation potentiation (PAP). PAP operates on the principle that heavy muscle loading creates increased stimulation of the central nervous system, resulting in greater motor unit recruitment and subsequently force production (1, 2).

There are two theories behind PAP. The first states that maximal muscle contraction yields an increased phosphorylation of myosin. The increased phosphorylation causes actin and myosin binding to be more responsive to calcium ions released from the sarcoplasmic reticulum (3).  This enhances force muscle production at the structural level of muscle (4).  As a result, faster contraction rates develop (1).

The second theory behind PAP involves the Hoffmann Reflex (4). The Hoffman reflex is excitation of muscle spindle nerve fibers. Physiologically, PAP increases speed of H-reflex, thus increasing the firing rate to muscle (5). It is this rate coding, and the aforementioned  phosphorylation of myosin that the NASM model suggests occurs during and following core exercise.

By stimulating the core musculature, the core will be active during the core exercise and also be activated during higher intensity exercise. Subsequently, the core is working longer and it is helping prevent injury by enhancing neuromuscular efficiency during higher intensity exercise.

What do you think? Which method do you prefer? Personally, through research and exercise experience, I favor the NASM version, but that could easily be attributed to my work experience at NASM. Nonetheless, the question remains and I think it would be a great research study comparing the two variables. Any doctoral students looking for a project?

References:

  1. Chiu, L.Z., Fry, A.C., Weiss, L.W., Schilling, B.K., Brown, L.E., & Smith, S.L. (2003). Postactivation potentiation response in athletic and recreationally trained individuals. Journal of Strength and Conditioning Research. 17(4), 671-677.
  2. Rixon, K.P., Lamont, H.S., & Bemden, M.G. (2007). Influence of type of muscle contraction, gender, and lifting experience on postactivation potentiation performance. Journal of Strength and Conditioning Research, 21(2), 500-505.
  3. Kravitz
  4. Hamada, T., Sale, D.G., MacDougall, J.D., & Tarnopolsky, M.A. (2000a). Postactivation potentiation, muscle fiber type, and twitch contraction time in human knee extensor muscles. Journal of Applied Physiology, 88, 2131-2137.
  5. Hodgson, M., Docherty, D., & Robbins, D. (2005). Post-activation potentiation underlying physiology and implications for motor performance. Sports Medicine, 25 (7), 385-395.