INJURY PREVENTION
slower speeds increase pre-activation. So to obtain quality and pre-activation, performing the exercise slowly with sufficient repetition before increasing difficulty through methods of increased resistance, load or quantity is appropriate.
CONCLUSION In summary, research supports pre-activation timing as a muscle contraction characteristic that is altered with both position and speed of movement. A link can be made between muscular training that improves the protective neuromuscular aspects. Following an assessment of foundation or functional movement faults, a strategy of slow and controlled movements should be employed. To enhance posture and injury prevention, it is necessary to correctly align joints and balance distribution of stress through all the soft tissue.
THE AUTHORS
Dr Richard DeMont PhD is an associate professor at Concordia University, Montreal, Canada. Dr DeMont teaches courses in the Athletic Therapy specialisation. His research interests include the area of neuromuscular control as it relates to injury prevention, performance, and rehabilitation through joint stabilisation.
Deanna Errico is a clinical assistant professor, in the Department of Physical Therapy and Health Sciences at Clarkson University in Potsdam, NY, USA. She is a licensed physical therapist and a certified athletic trainer.
References 1. Goldfuss AJ, Morehouse CA, LeVeau BF. Effect of muscular tension on knee stability. Medicine and Science in Sports and Exercise
The road to recovery is in your hands.
KEY POINTS
■ Reflexive control of muscle is not sufficient to avoid non-contact joint injury.
■ The majority of preparatory (pre-activation) muscle activation starts no longer than 150ms prior to force absorption.
■ Pre-activation is altered based on speed of movement and gravity dependent positions.
■ Appropriate sharing of muscle force production and absorption contributes to a balanced joint.
■ Position of exercise is important to share resources and maximise stability of the joint.
■ Repetition of movement in a controlled manner is a key to maximising the pre-activation and may be important to using the muscle for joint stability.
TAKE HOME MESSAGE Muscle activation in a controlled environment is crucial to the rehabilitation of joint injury, and can play a role in injury prevention. A strategy to emphasise the protection of the joint is balance of forces which may be enhanced by muscle pre-activation. To improve pre-activation, repetitive slow activation of the muscle in foundation exercises should
precede and be of greater emphasis in the preventative training programme.
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1973;5:267-271 2. Markoff K. Combined knee loading states that generate high anterior cruciate ligament forces. Journal of Orthopaedic Research 1995;13:930-935 3. DeMont RG, Lephart SM, Giraldo JL, Swanik CB, Fu FH. Muscle Preactivity of Anterior Cruciate Ligament-Deficient and -Reconstructed Females During Functional Activities. Journal of Athletic Training 1999;34(2)(Apr):115-120 4. Lephart SM, Kocher MS, Harner CD, Fu FH. Quadriceps strength and functional capacity after anterior cruciate ligament reconstruction. Patellar tendon autograft versus allograft. American Journal of Sports Medicine 1993;21(5)(Sep-Oct):738-743 5. Swanik CB, Lephart SM, Giraldo JL, Demont RG, Fu FH. Reactive Muscle Firing of Anterior Cruciate Ligament-Injured Females During Functional Activities. Journal of Athletic Training 1999;34(2)(Apr):121-129 6. Dietz V, Noth J, Schmidtbleicher D. Interaction between pre-activity and stretch reflex in human triceps brachii during landing from forward falls. Journal of Physiology 1981;311:113-125 7. DeMont RG, Grant RA. Comparison of leg muscle pre-activation during gravity assisted jumping. Journal of Athletic Training 2002;37(2);S28, 8. DeMont R, Pranesh A, Rakheja S. Pre-activation in hamstring running uphill versus level. World Federation of Athletic Training and Therapy. January 14th, 2007. Tokyo, Japan 9. Fraser SA, Li KZ, DeMont RG, Penhune VB. Effects of balance status and age on muscle activation while walking under divided attention. Journals of Gerontology: B Psychological Sciences and Social Sciences 2007;62(3)(May):P171-P178 10. Spain J. Prehabilitation. Clinical Sports Medicine 1985;4(3) (Jul):575-585 11. Hewett TE, Lindenfeld TN, Riccobene JV, Noyes FR. The effect of neu- romuscular training on the incidence of knee injury in female athletes. A prospective study. American Journal of Sports Medicine 1999;27(6) (Nov-Dec):699-706 12. Sahrmann S. Diagnosis and Treatment of Movement Impairment Syndromes. Mosby 2002. ISBN 0801672058 13. Cook G. Athletic Body in Balance. Human Kinetics, 2003. ISBN 0736042288 14. Livingston, Scott. Canadian Athletic Therapists Association, Conference: ‘Exercise is Therapy’ Winnipeg May 2007
sportEX dynamics 2007:14(Oct):14-16
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