The Instant Benefits of Concurrent Activation Potentiation

Let’s not pull any punches, we all want to lift more. What if I said to you that you could increase your numbers instantly by implementing one or two little tricks? Concurrent Activation Potentiation (CAP) may be just the ticket.

CAP refers to the augmentation of power output by means of a simultaneous, remote voluntary contraction (RVC). Put simply, the enhancement of power output during the activation of muscles elsewhere in the body. This is slightly different from the Post-activation Potentiation (PAP) phenomenon which refers to the enhancement of power output following the activation of certain musculature, predominantly the agonists. Consider these concepts during the example of a vertical jump. If seeking to employ PAP we would perform heavy squats several minutes prior to the jump. Employing CAP would involve the tight clenching of teeth and fists during the jump itself. By understanding the mechanisms and application of CAP it may be proposed that we can not only increase one-off performances but also enhance the training effect of various exercises.

Background:
CAP is far from a new concept in strength training, more a specific term that has been devised to encompass and explain some of the activation techniques that can be employed to provide an immediate performance benefit. CAP has its origins in the Jendrassik Manoeuvre (JM), a technique developed by Hungarian physician Erno Jendrassik in the late 19th century. The JM, originally devised in order to increase the amplitude of tendon reflexes in the lower limb, involves interlocking the hands together and attempting to them pull apart whilst simultaneously clenching the teeth. Whilst the JM itself may not be especially applicable to the majority of sporting performances, its use in research has helped us understand the potential mechanisms by which RVC may enhance performance. I won’t go in depth into mechanisms because a) they’re not fully understood and b) I’d bore you to tears, but put simply, it gives the nervous system a boost. The majority of recent research investigating the CAP phenomenon has been conducted by Dr. William Ebben at Marquette University so he’s the go to source for any further reference.

Different Types of RVC:
Aspects of the original JM (jaw clenching and gripping) have been isolated and tested for their performance benefit alone. Ebben, Flanagan and Jensen (2008) demonstrated that biting on a mouthguard during the performance of a countermovement jump increased the rate of force development (RFD) by almost 20% and peak ground reaction force (GRF) by just over 1.5%. Similarly, Tsuruike et al. (2003) and Péréon et al. (1995) both have highlighted the beneficial effects observed whilst performing gripping tasks.

The Valsalva Manoeuvre (VM), and resultant bracing of the abdominals, activates the majority of the musculature around the torso and may also serve as form of RVC. In addition to the activation of the core musculature the VM also causes an increase in intra-abdominal pressure which also aids force production. The positive effects of the VM are pretty well known so we won’t dwell on this too much.

It seems that there may be somewhat of an additive effect by utilising a number of different RVC, Ebben, Leigh and Geiser (2008) demonstrating that a combination of jaw clenching, bilateral hand gripping and the Valsalva Manoeuvre may elicit a greater performance benefit when performed in symphony. The authors reported a 17% increase in average knee extensor torque in comparison to the control condition. Increases of 11% and 15% and were observed following jaw clenching alone and jaw clenching, left hand gripping and the Valsalva. Interestingly they found that bilateral gripping alone had no effect on performances.

Ebben et al. (2010) has since demonstrated similar results in the back squat and countermovement jump. Clenching the jaw on a mouthguard, forcefully gripping and pulling the barbell down into the trapezius and performing a Valsalva manoeuvre resulted in a 32% increase in RFD and 26% increase in jump height during the squat jump, and a 23% increase in RFD and 4% increase in GRF during the back squat.

Utilising the Antagonists:
Although falling somewhere between CAP and PAP, activation of the antagonist musculature during the eccentric phase of a movement can have an immediate ergogenic effect on the concentric phase. Aside from eliciting benefits as consequence of the stretch shortening cycle, which is beyond the scope of this article, attenuating the eccentric component of a movement may cause a reduction in the level of neural inhibition applied to the concentric portion of the movement. This may provide an ergogenic rationale for the ‘active eccentric’ coaching points often given during lifts such as the squat and bench press. This is where athletes are instructed to actively assist the eccentric component of the movement, for example performing an active hip and knee flexion during the squat.

Augmented eccentric loading (AEL), which refers to the physically increasing the resistance encountered during the eccentric phase of a movement, has been shown to elicit gains in excess of 2% to 1RM bench press performance (Doan, et al., 2002) and also enhance acute hormonal responses (Ojasto & Hakkinen, 2009). Whilst the mechanisms are not investigated in these studies, Geertsen, Zuur and Nielsen (2010) have shown that contraction of tibialis anterior can potentiate subsequent contraction in the soleus via facilitation of motor evoked potentials. It still needs to be determined however, if such mechanisms are demonstrated in other agonist-antagonist pairings and if the same effect can be attained by attenuating the eccentric component without providing an additional load.

Potential Application:
Some types of RVC appear almost autonomous during near maximal efforts; the Valsalva Manoeuvre for example. This is not the case with all RVCs however, and certain techniques require appropriate coaching and cueing to be implemented. Without going in depth into coaching the entire lift, the following provides a list of specific coaching points that can be implemented into the concentric portion of the bench press with a specific view to maximising CAP.

  •  Drive the back of your head into the bench (engages neck extensors)
  •  Keep the shoulder blades back and together (engages rhomboids and mid/lower traps)
  •  Squeeze the bar hard (engages forearm flexors and extensors, increases activity in rotator cuff)
  •  Attempt to ‘pull the bar apart’ (engages lats and upper back musculature)
  •  Push knees out (engages hip abductors)
  •  Drive your toes through the front of your trainers and heels into the floor (depending on the foot position of your set-up) (engages knee flexors and extensors)
  •  Perform the Valsalva Manoeuvre (engages deep core musculature, increases intra-abdominal pressure)

References:
Doan, B. K., Newton, R. U., Marsit, J. L., Triplett-McBride, N. T., Koziris, L. P., Fry, A. C., et al. (2002). Effects of increased eccentric loading on bench press 1RM. Journal of Strength and Conditioning Research, 16(1), 9-13.
Ebben, W. B., Flanagan, E. P., & Jensen, R. L. (2008). Jaw clenching results in concurrent activation potentiation during the countermovement jump. Journal of Strength and Conditioning Research, 22(6), 1850-1854.
Ebben, W. B., Kaufmann, C. E., Fauth, M. L., & Petushek, E. J. (2010). Kinetic analysis of concurrent activation potentiation during back squats and jump squats. Journal of Strength and Conditioning Research, 24(6), 1515-1519.
Ebben, W. B., Leigh, D. H., & Geiser, C. F. (2008). The effect of remote voluntary contractions on knee extensor torque. Medicine and Science in Sport and Exercise, 40(10), 1805-1809.
Geertsen, S. S., Zurr, A. T., & Nielsen, J. B. (2010). Voluntary activation of ankle muscles is accompanied by subcortical facilitation of their antagonists. Journal of Physiology, 588(13), 2391-2402.
Ojasto, T., & Hakkinen, K. (2009). Effects of difference accentuated eccentric loads on acute neuromuscular, growth hormone, and blood lactate responses during a hypertrophic protocol. Journal of Strength and Conditioning Research, 23(3), 946-953.
Péréon, Y., Genet, R., & Guihéneuc, R. (1995). Facilitation of motor evoked potentials: Timing of jendrassik maneuver effects. Muscle and Nerve, 18(12), 1427-1432.
Tsuruike, M., Koceja, D. M., Yabe, K., & Shima, N. (2003). Age comparison of H-reflex modulation with the Jendrássik maneuver and postural complexity. Clinical Neurophysiology, 114(5), 945-953.

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