Friday, May 27, 2011

Perturbation training

       In coming blog posts, I would like to introduce essentially what I believe to be a "pyramid" of physical activity requirements needed to attain optimal movement ability. Discrete movement components include strentgth, mobility, balance, coordination, agility, & quickness (acceleration and deceleration) among others.  I dont think it is neccessary for everyone to neccessarily follow the pyramid, its just a source of reference to those interested in attaining sound movement proficiency. Too many people get caught up in one specific paradigm of training only to lose out on other critical components needed to ensure optimal movement. For example bodybuilding without any focus on flexibility and range of motion, or pilates whilst neglecting any form of heavy muscle strengthening. I don't want to be too verbose but it is interesting how a movemnt pyramid could further serve as microcosm for total health as well. In an ideal situation one could shoot for optimal movement along with optimal rest, nutrition, endurance, stress management, and so forth, again forming something of a "fluid" pyramid that adjusts due to training goal and/or requirements.

     Today we'll be specifically focusing on perturbation training. I plan to explain what it is, how it is already built into many activities, the benefits, some research behind it, and finally how to carry it out in one's program.

     Perturbations are a "disturbance of motion, course, arrangement, or state of equilibrium" according to Websters. Perturbation training can basically be thought of of balance training on steroids. However balance training alone consist of very basic exercises such as standing on one foot or with the eyes closed. For athletes and even those in the general population, it is indicated that the exercise be a bit more intense and metabolically more taxing in order to increase time efficiency which  have discussed before (here). Perturbation training taxes 1) the somatosensory, 2) the vestibular, and 3) the visual systems (1). The somatosensory system literally means body sensing, and essentially refers to an individuals ability to sense his or her position in space. For the vestibular system, we're thinking of the the central equilibrium center in head. It is also closely associated with the cochlea, or the hearing/auditory center. In training, the visual and vestibular systems are generally not greatly manipulated, and most of the stress, and thus subsequent adaptations occur within the somatosensory system. The somatosensory system consists myriad receptors that detect different sensations (1). 
Various sensory receptors
 Copied from Taylor, J.B.  
Lower extremity perturbation training, Strength and Cond. Journal 33(2) 76-8

  As I said earlier, perturbation training is built into many activities already. Consider boxing-out in basketball or two linemen duking it out in the trenches in football.The opponent is constantly disturbing the athletes equilibrium with their body. Another example would be skating where it takes  a certain level of ankle stablity to maintain the position of the ice-skates, and further manipulate them to porduce movement. It's my personal belief, that these occurrences in sport are what render athletes more athletic. Many sports involve all of the components to good movment that I discussed earlier in the article, mobility, agility, and so forth, where as when the general population takes on an exercise they inadvertently neglect many of the components of movement. One of the components often neglected are perturbations.  

    So one might be asking, Who cares about perturbations? Well I have already pointed out the ability to overcome perturbations is an important component of sport. It is also important to be a able to overcome perturbations in general life also. A simple example I often give is when it is icy outside, if one has no ability to overcome perturbations, it's going to be a rough winter. General situations in life come to mind, such as missing a step on the way up a light of stairs (you know it has happened to you) and other  everyday activities that don't involve sitting in front of the tv or computer. Perturbation training  is particulary important for females and those that need optimal range of movement and reaction at the knee joint (e.g. soccer players and other athletes).

    In fact most of the published literature to date has focused on lower body perturbations and as a point of reference perturbation training hs been found to increase range of movement about the joint and decrease the phenomenon of co-contraction (2, 3, 4). Co-contraction is essentially when antagonistic muscles about the same joint simultaneously contract to prevent extreme motion. Think of the quadriceps and hamstrings both contracting at the knee joint. This also is relevant to most the population because they tend tend to be quadricep dominant, meaning their quadriceps are overpowering their hamstring muscles. This is not conducive to optimal joint stability and reaction.

     However, we can build perturbations into our training quite easily and in different ways to address our specific needs. Remember in the examples earlier, the basketball, football,  and other athletes are consistently on a stable surface were the perturbation comes from an external factor in the environment (ie opponent) whereas in a sport like hockey, there is intrinsic instability built in to the sport's playing surface. One form of surface perturbation involves the use of a bosu dome, or even a rollerboard or rockerboard when available. The bosu dome can generally be found in many commercial gyms. You can use these to finish up a workout with exercises such as a push up with the dome upside down or squats with the dome right-side up or up-side down. A nice progression for the lower body movements would include closing the eyes, to further stress the somatosensory system, with the loss of visual input. I will copy an image below for those unfamiliar with this equipment below.

     The advantage of both forms of perturbation that I have mentioned or training of the somatosensory receptors we discussed earlier. There is also an endurance component to this. In addition to the balance component, the core is taxed to avoid the perturbation as well and the exercises are both metabolically taxing while offering some degree of a muscular strengthening component. For those with poor mobility, these exercises even address that area as well. I recommend saving these exercises for near the end of practice/training. Obviously we receive greater sensory input and act accordingly when we are fresh. However we want to be able to maintain this activity, which is why I recommend saving perturbation training for towards the end of the exercise training session. Perturbation training on the bosu or with the partner assisted perturbation is not the main strengthening or endurance component of training but does offer critical potential for adaptation, so think of it as an accessory or supplement to to the prime exercises in a session, back squat, deadlift, rows, etc. for strength and bike sprints, running, complexes, etc for conditioning.

     The current recommendations in the literature are for 60-90 seconds of perturbation followed by 60-90 second rest intervals to allow for tissue and neuromuscular recovery (1). In the real world, legendary strength & conditioning coach Vern Gambetta has recommended dedicating about 5-10 minutes of training time to these exercises a day, about 3-4 dys per week(5). 

Add caption

      I really like and trust Vern's advice. The guy has been around longer than the journals that pertain to strength and conditioning and he has worked with athletes spanning from high school to the pros (check out his website). In addition, perturbation can be thought of as just one small piece of the optimal movemtn pyramid. However for core stability, improved balance, and gait reaction time, and even for the rehabilitation setting (6), 5 to 10 minutes of perturbation built into the training session is crucial to to tax the systems we discussed and gain the benefits discussed as well.

Bosu Dome
      However before you go overboard with the ol' bosu dome, remember what I just wrote, not all perturbations come from unstable surfaces. Eric Cressey has written about this extensively for those interested in further reading (see here). Other measures one might take to engage in perturbation would be having a partner or trainer offer external perturbations during the performance of exercises such as the split squat or the plank. 

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