The Jeet Kune Do Fighting Stance:
Improvement Through Transfer of Training
When Bruce Lee developed the martial art of Jeet Kune Do (JKD) he used scientific principles from biomechanics and physiology to create a hybrid fighting stance. Unlike many martial arts where the practitioner faces sideways with the strong or dominant side back, the Jeet Kune Do practitioner uses more of a square stance with the dominant side forward. To facilitate movement the heel of the back foot is slightly raised, the knees are slightly bent, and the body is slightly crouched (Tom, 2005). This particular fighting stance provides the base from which all techniques are initiated. To maintain a solid base from which to move the practitioner must have balance, strength, and power; and to progress, a plan must be implemented to develop these attributes.
To improve the physical aspects used in the JKD fighting stance, the specific adaptation to imposed demands (SAID) principle is employed. The SAID principle is based on the transfer of training concept that the body’s response to exercise and training is very specific to the type of activity, volume, and intensity placed upon it. The more specific the training is to the activity, the higher the level of performance for that specific activity will be (Wilmore, Costill & Kenney, 2008). Rhea (nd) recommends that the specifics of the activity be mimicked as closely as possible. When observed, the JKD fighting stance resembles a lunge or a split squat, therefore it makes sense to utilize exercises that enhance a lunge or split squat in various settings. Using transfer of training protocols, a plan to improve the physical aspects of the JKD fighting stance can be developed.
Over the past few years core training has permeated the strength and conditioning field as well as the rehabilitation arena. The core consists of 29 muscles or pairs of muscles that control and stabilize the lumbo pelvic-hip complex (LPHC: lumbar spine, pelvis, and hip girdle) (Akuthuota, Ferrerio, Moore & Fredricson, 2008). Although while in the JKD fighting stance power is generated by pushing off of the ground, the power is transferred for kinetic chain movement, proximal to distal, from the core. To strengthen the core, basic exercises such as bracing, quadrupeds, and side planks should be included in any exercise program. More specific exercises can be performed to address the JKD practitioner’s particular needs. For example lunging on an unstable surface or utilizing multi-planer lunges while maintaining spinal control closely mimics movement initiated from the JKD fighting stance. Moving quickly into these positions by jumping will stimulate the nervous system and help ensure automatic postural control (Akuthuota et al. 2008) and in turn a solid base.
Stability has become another catch phrase for fitness trainers and is defined as the resistance to the disruption of equilibrium (Hall, 2007). Perhaps a more definitive way to describe stability for specific activity would be dynamic balance which is the ability to control equilibrium (Hall, 2007). Dynamic balance training requires maintaining postural equilibrium during movement. Simultaneously training balance and movement makes use of a number of neurological pathways as it requires feedback for motion as well as a musculoskeletal response (Clark & Russell, 2007). Therefore, the objective of balance training is to promote balance by disturbing the equilibrium of the musculoskeletal system so that there is an increase in neuromuscular capacity and a decrease in action/reaction time (Yaggie & Campbell, 2006). Movement from the JKD fighting stance requires dynamic balance as the center of gravity (COG) is quickly shifted from one foot or leg to the other during the execution of both defensive and offensive techniques.
Although there is debate on whether or not stability training on a Both Sides Up (BOSU) balance trainer can increase strength, it does increase proprioception. Improvements in postural limits involving displacement of the COG and sway have also been associated with balance training on a BOSU (Yaggie & Campbell, 2006). Adding resistance by incorporating pushing or pulling movements can increase disruptions to the COG. Further progression can be made by integrating the use of single leg exercises, rotational movements around the three axis (anteroposterior, mediolateral, and longitudinal), and movement in all three planes of motion (sagittal, frontal, and transverse) (Clark & Russell, 2007). For the JKD practitioner, balance training can increase postural limits, improve dynamic balance, and provide a better sense of stability and base from which to initiate movement.
The benefits of strength training are numerous; for activity and performance gains in strength will provide an increase of force, power, and endurance (Wilmore et al. 2008). For improvement in a specific movement, as mentioned, Rhea (nd) states that the specifics of the activity need to be closely mimicked, therefore, for strength gains, the active muscles need to be indentified and then strengthened. Through observation and electromyography (EMG) Jonhagen, Halverson & Benoit (2009) determined that during walking and jumping lunges the quadriceps and the gastrocnemius both utilized eccentric contractions while the hamstring displayed only an isometric contraction. According to Clark and Russell (2007), during a lunge the gluteus maximus and quadriceps are the agonists, the calf muscles (gastrocnemius and soleus), and the hamstrings are the synergists, and the tibialis muscles as well as the LPHC act as stabilizers. For strength training, exercises that focus on the quadriceps, the gluteus maximus, and the calf muscles will benefit the JKD practitioner.
The obvious exercise that mimics the JKD stance is the lunge: walking, jumping, with weight, or a split squat. However, there are other compound exercises that can help strengthen the same muscles. Boudreau, Dwyer, Mattacola, Lattermann, Uhl, & McKeon (2009), using a 16-point EMG system, found that the rectus femoris and the gluteus maximus are activated to a greater degree during the performance of a single leg squat than during the performance of a lunge. The calf can be strengthened by performing standing or seated calf raises and increases in calf strength have also been reported by the addition of plantar flexion at the end of a maximal velocity leg press (Fimland, Helgerud, Gruber, Leivseth & Hoff, 2009). Although the apparent exercise to increase strength utilized in the JKD fighting stance is a lunge, other strength training exercises should also be incorporated into a training program.
While strength is the maximum force that a muscle generates, power is strength combined with the speed of movement (Wilmore et al. 2008). One of the most accepted ways to increase power is to employ plyometric training. Plyometrics are used to improve the stretch-shortening cycle to facilitate recruitment of motor units by storing energy during the eccentric phase of an exercise and utilizing it during the concentric phase. Plyometric training uses ballistic movement patterns similar to those used in athletic activities (Vissing, Brink, Lonbro, Sorenson, Overgaard, Danborg et al. 2008). Box jumps, scissor jumps, medicine ball throws, and jumping rope are all examples of plyometric training (Brown & Ferrigno, 2005) that will increase the power used in the techniques initiated from the JKD fighting stance, as well as help the practitioner return to a balanced base.
Once the exercises have been determined and implemented there needs to be a method for verifying progression. Knowledge of the JKD fighting stance allows an observer to qualitatively measure the outcome. By observing base and balance, initiated movement, and return movement, a judgment can be made as to whether or not the desired results have been achieved. Through qualitative analysis, movements can be critiqued, errors can be scrutinized, and corrections can be recommended (Hall, 2007).
Although qualitative analysis may be of more use when analyzing the JKD stance as a whole, individual movements can also be quantitatively assessed. The outcomes for core strength, balance, strength, and power can be numerically defined. To measure core strength, Akuthuota et al. (2008) lists ten exercises that include multi-plane, weight-bearing movements of the global core as well as individual muscles. Some of the recommended assessments are the prone stability test, side and pelvic bridging endurance tests, trunk curl, and multi-planer single leg squat tests. For stability, testing total sway as well as body displacement can be measured using a force platform and/or specialized software. For those with more modest means, simply keeping track of the time balanced on a BOSU for each exercise will give an indication of progress (Yaggie & Campbell, 2006). The measurement for strength training is straightforward; can the performer safely lift more now (in terms of weight, repetitions, or total volume) then at the start of the training program. A recent development in the measurement of plyometric training, particularly when balance and postural stability upon landing is critical, is time to stabilization (TTS). TTS measures how long, after the conclusion of the movement, it takes to regain base and balance (Ebben, VanderZanden, Wurm & Petushek, 2010). By the use of a force platform to measure stability, TTS provides a means to quantify the dynamic landing involved with plyometric training. Each of the individual components involved in the JKD fighting stance should be measured prior to and at the completion of the training program using quantitative analysis.
Although the movements associated with the JKD fighting stance itself are minimal, the ability to securely move in and out of the base of support is of utmost importance. The practitioner needs to be able to execute a technique and maintain or regain a strong, stable base. Using the SAID principle and closely mimicking the movements involved will help in the development of a training program. Selecting appropriate exercises that transfer specific skills for balance, strength, and power will lead to improvements in performance. Using both qualitative and quantitative analysis, the results of the training program can be assessed and adjusted for individual needs as well as further improvement.
References:
Akuthuota, V., Ferrerio, A., Moore, T. & Fredricson, M. (2008) Core stability exercise principles. Current Sports Medicine Reports. 890X/0701/39-44
Boudreau, S., Dwyer, M., Mattacola, C., Latterman, C., Uhl, T., & McKeon, J. (2009) Hip-muscle activation during the lunge, single-leg squat, and step-up-and over exercises. Journal of Sport Rehabilitation, 2009, 18, 91-103
Brown, L., & Ferrigno, V. (2005) Training for speed, agility, and quickness. (pp. 148, 157, 168, 177, 178) Champaign, IL: Human Kinetics
Clark MA, & Russell A. (2007) Optimum performance training for the performance enhancement specialist; integrated balance training. Calabasas, CA: National Academy of Sports Medicine.
Ebben, W., VanderZanden, T., Wurm, B., & Petushek, E. (2010) Evaluating plyometric exercises using time to stabilization. Journal of Strength and Conditioning Research, 24(2), 300–306
Fimland, M., Helgerud, J., Gruber, M., Leivseth, G., & Hoff, J. (2009) Functional maximal strength training induces neural transfer to single-joint tasks. European Journal of Applied Physiology. doi 10.1007/s00421-009-1096-4
Hall, S. (2007) Basic biomechanics. (pp. 44-48, 445) New York: McGraw-Hill.
Jonhagen, S., Halverson, K., & Benoit, D. (2009) Muscle activation and length changes during two lunge exercises: implications for rehabilitation. Scandinavian Journal of Medicine and Science in Sports 2009: 19: 561–568
Rhea, M. (nd) Transfer of training to sport performance. Retrieved October 26, 2010 from http://academics.ashs.atsu.edu/hmvideos/rhea/HM503/transfer.wmv
Tom, T. (2005). The straight lead, the core of Bruce Lee’s Jun Fan Jeet Kune Do. (pp. 25-33) Boston: Tuttle Publishing.
Vissing, K., Brink, M., Lonbro, S., Sorenson, H., Overgaard, K., Danborg, K., et al. (2008) Muscle adaptations to plyometrics vs. resistance training in untrained young men. Journal of Strength and Conditioning Research 22(6), 1799–1810 2008
Wilmore, J., Costill, D., & Kenney, W. (2008) Physiology of sport and exercise. (pp. 189, 190, 195, 247-248) Champaign IL: Human Kinetics.
Yaggie, J., & Campbell, B. (2006) Effects of balance training on selected skills. Journal of Strength and Conditioning Research. 20(2), 422-428
