在不稳定的情况下的力量训练

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Instability Resistance Training (en anglais seulement)David Behm, PhD, CSEP CEP
Originally published in the CSEP member newsletter, Communiqué, March 2009.
There are many instances in daily life and sport where individuals must perform tasks under unstable conditions. According to the concept of training specificity, since not all forces are produced under stable conditions (i.e. shooting a puck while balancing on a single skate blade in hockey, performing a routine on a balance beam in gymnastics, changing direction rapidly by pivoting on one foot on uneven natural turf in football, soccer, field hockey or other sports), then training must attempt to closely mimic the demands of the sport or occupation. Resistance training involving balls, platforms and other devices to induce varying degrees of instability are very popular in contemporary fitness establishments. Physical therapists have been using "Physio Balls" since before World War II based on neuromuscular training techniques suggested by Sherrington and others. Physical therapists, especially the Germans and Swiss (consequently, the term Swiss balls) were especially active in using balls for sports training and therapy. Instability can be produced with the base from which the exercise is performed (i.e. ball, wobble board) or by placing body segments or resistance outside the base of support of the body (i.e. unilateral dumbbell resisted movements). There are both desirable and undesirable consequences of instability resistance training.
Instability resistance exercises induce high muscle activation of postural limb and trunk muscles. The increased activation has been attributed to the increased stabilization functions. The increased stress associated with instability training has been postulated to promote greater neuromuscular adaptations such as decreased co-contractions of antagonists, improved co-ordination and confidence in performing a skill. In addition, resistance exercises using a single arm (unilateral) will also cause greater activation of the contralateral side trunk stabilizers. Balance training which can be described as instability activities without an emphasis on strength or endurance decreases the incidence of athletic injuries. In addition, instability resistance training with its high muscle activation and lower external stress on joints could also be beneficial for general musculoskeletal health and certain types of rehabilitation.
On the undesirable side, unstable conditions can lead to decreased force and power output, decreased range of motion and velocity. Furthermore ground based weight training exercises such as squats and dead lifts can provide equal or greater trunk activation than using instability devices. Another study has also reported that highly trained individuals do not experience greater trunk activation when performing exercises under light or moderately unstable conditions.
Since many of the benefits of instability devices can be achieved with high resistance involving ground based free weights, advanced resistance trained individuals may not need to emphasize this type of training in their strength and power training programs. Elite athletes represent a small segment of the population and the training methods employed to enhance performance (i.e. Olympic lifts) might be different from the training methods commonly employed to improve general health (i.e. instability resistance exercises). However advanced resistance trainers might want to employ instability resistance exercises within their periodized training programs. Persistent training with high loads and volumes can lead to overtraining effects. Since the concept of periodization emphasizes the importance of modulating the volume and intensity of the training load over time, the lower force and power outputs associated with instability resistance training may be beneficial for those training cycles employing lower loads. During these cycles high activation of both the limb and trunk muscles can be maintained while decreasing the external stresses on the joints (especially the vertebrae and discs of the back with heavy squats and other similar exercises) (Behm and Anderson 2006).
The benefits of instability resistance training may be more pronounced for those individuals pursuing primarily general health and rehabilitation benefits and not participating in training with free weights involving high loads. For recreational athletes or fitness enthusiasts not interested in performing heavy ground based weight exercises (i.e. squats, deadlifts and others) the amount of instability should be light to moderate when strength or power training is an important focus. When a person cannot stay erect (i.e. attempt to stand on a Swiss ball), the focus will be on balance with very little ability to exert force. With moderate to light instability such as sitting on a Swiss ball or standing on foam rollers there is less focus needed for balance and more concentration on strength or power. On the other hand if the focus is on trunk activation, more instability can be applied. The purpose of instability exercises need not be significant strength gains, but an attempt to improve balance, stability and proprioceptive capabilities. The examination of the literature suggests that when recreational fitness enthusiasts are implementing a resistance training program for musculoskeletal health, both stable and unstable exercises be included to ensure an emphasis on both higher force (stable) and balance (unstable) stressors to the neuromuscular system (Behm and Anderson 2006, Anderson and Behm 2005 Wahl and Behm 2008).
References

• Anderson K., Behm D.G. Intrinsic and Extrinsic Factors Affecting Balance and Stability. Sports Medicine 35(1): 43-53, 2005
• Behm D.G. , Anderson K. The Role of Instability with Resistance Training. Journal of Strength and Conditioning Research 20(3): 716-722, 2006
• Wahl M.J., Behm D.G. Not all instability training devices enhance muscle activation in highly resistance-trained individuals. Journal of Strength and Conditioning Research 22(4): 1360-1370, 2008
  

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