![POSITION STAND / PRISE DE POSITION
Canadian Society for Exercise Physiology position
stand: The use of instability to train the core in
athletic and nonathletic conditioning
David G. Behm, Eric J. Drinkwater, Jeffrey M. Willardson, and Patrick M. Cowley
Abstract: The use of instability devices and exercises to train the core musculature is an essential feature of many training
centres and programs. It was the intent of this position stand to provide recommendations regarding the role of instability
in resistance training programs designed to train the core musculature. The core is defined as the axial skeleton and all
soft tissues with a proximal attachment originating on the axial skeleton, regardless of whether the soft tissue terminates
on the axial or appendicular skeleton. Core stability can be achieved with a combination of muscle activation and intra-ab-
dominal pressure. Abdominal bracing has been shown to be more effective than abdominal hollowing in optimizing spinal
stability. When similar exercises are performed, core and limb muscle activation are reported to be higher under unstable
conditions than under stable conditions. However, core muscle activation that is similar to or higher than that achieved in
unstable conditions can also be achieved with ground-based free-weight exercises, such as Olympic lifts, squats, and dead
lifts. Since the addition of unstable bases to resistance exercises can decrease force, power, velocity, and range of motion,
they are not recommended as the primary training mode for athletic conditioning. However, the high muscle activation
with the use of lower loads associated with instability resistance training suggests they can play an important role within a
periodized training schedule, in rehabilitation programs, and for nonathletic individuals who prefer not to use ground-based
free weights to achieve musculoskeletal health benefits.
Key words: resistance training, trunk muscles, back, balance, stability.
Re´sume´ : L’utilisation d’appareils et d’exercices de de´stabilisation pour l’entraıˆnement des muscles profonds du tronc fait
partie du sce´nario de base de plusieurs centres et programmes d’entraıˆnement. Le propos ici est de formuler des recom-
mandations sur le roˆle de l’instabilite´ dans les programmes d’entraıˆnement a` la force des muscles profonds. Ce noyau mus-
culosquelettique de l’organisme est constitue´ du squelette axial et de tous les tissus mous dont l’insertion proximale est sur
le squelette axial, quelle que soit la zone d’insertion distale, sur le squelette axial ou appendiculaire. La stabilite´ du noyau
musculosquelettique est le re´sultat combine´ de l’activation des muscles et de la pression intra-abdominale. Le contrevente-
ment abdominal est, preuve a` l’appui, plus efficace que le creusement abdominal quand il est question d’optimiser la stabi-
lite´ abdominale. Meˆme si l’activation des muscles profonds du tronc et des membres est, dit-on, plus grande quand les
meˆmes exercices sont accomplis en condition d’instabilite´, on peut observer une activation semblable ou meˆme supe´rieure
au moyen d’exercices au sol avec des poids libres comme la leve´e olympique, l’extension des membres infe´rieurs et le
souleve´ de terre. Du fait que l’ajout d’une base instable lors de la re´alisation d’exercices de force suscite une diminution
de la force, de la puissance, de la ve´locite´ et de l’amplitude de mouvement, on ne le recommande pas comme mode prin-
cipal d’entraıˆnement dans les se´ances de conditionnement physique. En revanche, l’importante activation musculaire lors
d’exercices a` faible charge en condition d’instabilite´ souligne l’utilite´ de ces derniers dans la pe´riodisation de l’entraıˆ-
nement, dans les programmes de re´adaptation et aupre`s d’individus non sportifs pre´fe´rant ne pas faire d’exercices avec des
poids libres quand le but est d’ame´liorer la sante´ musculosquelettique.
Mots-cle´s : entraıˆnement a` la force, muscles du tronc, dos, e´quilibre, stabilite´.
[Traduit par la Re´daction]
Received 21 May 2009. Accepted 1 October 2009. Published on the NRC Research Press Web site at apnm.nrc.ca on 22 January 2010.
D.G. Behm.1 School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada.
E.J. Drinkwater. School of Human Movement Studies, Charles Sturt University, Panorama Avenue, Bathurst, 2795, NSW, Australia.
J.M. Willardson. Kinesiology and Sports Studies Department, Eastern Illinois University, Charleston, IL 61920, USA.
P.M. Cowley. Department of Exercise Science, Syracuse University, Syracuse, NY 13207, USA.
1Corresponding author (e-mail: dbehm@mun.ca).
109
Appl. Physiol. Nutr. Metab. 35: 109–112 (2010) doi:10.1139/H09-128 Published by NRC Research Press](https://image.slidesharecdn.com/csep-position-stand-2-e-130911224623-phpapp02/85/Position-Stand-1-320.jpg)
Position Stand
- 1. POSITION STAND / PRISE DE POSITION Canadian Society for Exercise Physiology position stand: The use of instability to train the core in athletic and nonathletic conditioning David G. Behm, Eric J. Drinkwater, Jeffrey M. Willardson, and Patrick M. Cowley Abstract: The use of instability devices and exercises to train the core musculature is an essential feature of many training centres and programs. It was the intent of this position stand to provide recommendations regarding the role of instability in resistance training programs designed to train the core musculature. The core is defined as the axial skeleton and all soft tissues with a proximal attachment originating on the axial skeleton, regardless of whether the soft tissue terminates on the axial or appendicular skeleton. Core stability can be achieved with a combination of muscle activation and intra-ab- dominal pressure. Abdominal bracing has been shown to be more effective than abdominal hollowing in optimizing spinal stability. When similar exercises are performed, core and limb muscle activation are reported to be higher under unstable conditions than under stable conditions. However, core muscle activation that is similar to or higher than that achieved in unstable conditions can also be achieved with ground-based free-weight exercises, such as Olympic lifts, squats, and dead lifts. Since the addition of unstable bases to resistance exercises can decrease force, power, velocity, and range of motion, they are not recommended as the primary training mode for athletic conditioning. However, the high muscle activation with the use of lower loads associated with instability resistance training suggests they can play an important role within a periodized training schedule, in rehabilitation programs, and for nonathletic individuals who prefer not to use ground-based free weights to achieve musculoskeletal health benefits. Key words: resistance training, trunk muscles, back, balance, stability. Re´sume´ : L’utilisation d’appareils et d’exercices de de´stabilisation pour l’entraıˆnement des muscles profonds du tronc fait partie du sce´nario de base de plusieurs centres et programmes d’entraıˆnement. Le propos ici est de formuler des recom- mandations sur le roˆle de l’instabilite´ dans les programmes d’entraıˆnement a` la force des muscles profonds. Ce noyau mus- culosquelettique de l’organisme est constitue´ du squelette axial et de tous les tissus mous dont l’insertion proximale est sur le squelette axial, quelle que soit la zone d’insertion distale, sur le squelette axial ou appendiculaire. La stabilite´ du noyau musculosquelettique est le re´sultat combine´ de l’activation des muscles et de la pression intra-abdominale. Le contrevente- ment abdominal est, preuve a` l’appui, plus efficace que le creusement abdominal quand il est question d’optimiser la stabi- lite´ abdominale. Meˆme si l’activation des muscles profonds du tronc et des membres est, dit-on, plus grande quand les meˆmes exercices sont accomplis en condition d’instabilite´, on peut observer une activation semblable ou meˆme supe´rieure au moyen d’exercices au sol avec des poids libres comme la leve´e olympique, l’extension des membres infe´rieurs et le souleve´ de terre. Du fait que l’ajout d’une base instable lors de la re´alisation d’exercices de force suscite une diminution de la force, de la puissance, de la ve´locite´ et de l’amplitude de mouvement, on ne le recommande pas comme mode prin- cipal d’entraıˆnement dans les se´ances de conditionnement physique. En revanche, l’importante activation musculaire lors d’exercices a` faible charge en condition d’instabilite´ souligne l’utilite´ de ces derniers dans la pe´riodisation de l’entraıˆ- nement, dans les programmes de re´adaptation et aupre`s d’individus non sportifs pre´fe´rant ne pas faire d’exercices avec des poids libres quand le but est d’ame´liorer la sante´ musculosquelettique. Mots-cle´s : entraıˆnement a` la force, muscles du tronc, dos, e´quilibre, stabilite´. [Traduit par la Re´daction] Received 21 May 2009. Accepted 1 October 2009. Published on the NRC Research Press Web site at apnm.nrc.ca on 22 January 2010. D.G. Behm.1 School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada. E.J. Drinkwater. School of Human Movement Studies, Charles Sturt University, Panorama Avenue, Bathurst, 2795, NSW, Australia. J.M. Willardson. Kinesiology and Sports Studies Department, Eastern Illinois University, Charleston, IL 61920, USA. P.M. Cowley. Department of Exercise Science, Syracuse University, Syracuse, NY 13207, USA. 1Corresponding author (e-mail: dbehm@mun.ca). 109 Appl. Physiol. Nutr. Metab. 35: 109–112 (2010) doi:10.1139/H09-128 Published by NRC Research Press
- 2. Rationale Training of the core musculature is an important facet that has gained renewed emphasis in the scientific and professio- nal literature, as well as in the sports training and rehabilita- tion fields. For the average healthy individual, training the core musculature is emphasized to maintain musculoskeletal health, especially related to the prevention of low back pain (Behm and Anderson 2006). For the injured individual, training the core musculature is used to treat and rehabilitate trunk-related musculoskeletal injuries (Caraffa et al. 1996; Cumps et al. 2007; Forestier and Toschi 2005). For the ath- letic individual, training the core musculature is not only ad- vocated for the prevention of injury, it also enhances performance (Behm and Anderson 2006). According to the principle of training specificity (Behm 1995; Behm and Sale 1993), and since motion for some sports may occur on relatively unstable surfaces (e.g., skiing, snowboarding), training must attempt to closely address the demands of the sport. Instability-based exercises are a very popular means of attempting to address this aspect of sports performance. A significant body of scientific literature has evaluated the role of instability in resistance training programs designed to train the core musculature. The anatomical core is defined as the axial skeleton and all soft tissues with a proximal attachment originating on the axial skeleton, regardless of whether the soft tissue ter- minates on the axial or appendicular skeleton (Behm et al. 2010). Achieving sufficient spinal stability represents the complex interaction of passive (i.e., spinal ligaments, inter- vertebral discs, and facet articulations) and active muscle and neural subsystems (Panjabi 1992); thus, a single muscle or structure cannot be identified as the most important spinal stabilizer. The combination of core muscles recruited is de- pendent on the task demands (i.e., posture, external forces). The global axial skeleton stabilizers include the large, superficial muscles (e.g., rectus abdominis, external oblique abdominis, erector spinae group) that provide multisegmen- tal stiffness over a greater range and also act as prime mov- ers during dynamic activities (Behm et al. 2010). Other core muscles might be considered axial-appendicular transfer muscles that connect the trunk (i.e., axial skeleton) to the upper and lower extremities (i.e., appendicular skeleton) via the pelvic girdle and shoulder girdle, respectively (Behm et al. 2010). These core muscles function in transferring tor- ques and angular momentum during the performance of inte- grated kinetic chain activities, such as throwing or kicking (Cresswell and Thorstensson 1994; Kibler et al. 2006; Will- ardson 2007). Weakness in the core musculature may inter- rupt the transfer of torques and angular momentum, resulting in decreased performance. Spinal stability is dependent on the appropriate combina- tion and intensity of muscle activation and the generation of intra-abdominal pressure. Abdominal bracing appears to be more effective than abdominal hollowing to optimize spinal stability (Grenier and McGill 2007). Specific training practi- ces aimed at targeting the spinal stabilizing muscles (core) are an important consideration for activities of daily living, athletic performance, and the rehabilitation of low back pain (Abenhaim et al. 2000). Instability applied to resistance training provides different responses than training under stable conditions. Performing resistance exercises on unstable surfaces is reported to in- crease activation of the core musculature, compared with performing the same exercises under stable conditions, whether the instability is derived from a platform (Anderson and Behm 2004, 2005; Marshall and Murphy 2006b; San- tana et al. 2007) or the movement of the limbs (Gaetz et al. 2004; Holtzmann et al. 2004; Marshall and Murphy 2006a). However, unilateral resisted actions (whether ground- based or supported on an unstable base) can also provide a disruptive moment arm (torque) to the body, providing an additional means of increasing the core musculature (Behm et al. 2003). Exercises performed on unstable surfaces can not only increase core muscle activation, but can also in- crease limb muscle activation (Anderson and Behm 2005; Marshall and Murphy 2006a, 2006b) and co-contractions (Behm et al. 2002). However, other research demonstrates that ground-based lifts, such as squats and dead lifts, provide even higher core activation than callisthenic-style exercises performed on unstable surfaces (Hamlyn et al. 2007). Fur- thermore, unstable resisted actions can result in decreased force (Anderson and Behm 2004; Behm et al. 2002; McBride et al. 2006), power (Drinkwater et al. 2007; Kor- necki and Zschorlich 1994), velocity, and range of motion (Drinkwater et al. 2007). Resistance trained individuals with years of experience performing ground-based free-weight lifts may not respond with higher activation of the core mus- culature when performing exercises on moderately unstable bases (Wahl and Behm 2008). Training programs must be structured so that athletes are prepared for the wide variety of postures and external forces encountered during sports participation. This is best accomplished through the per- formance of a wide variety of exercises that encompass all planes of movement and varying loads. Recommendations Athletes Athletes training for maximal strength, power, and veloc- ity of movement should emphasize higher-intensity ground- based lifts (e.g., Olympic lifts, squats, and dead lifts) and not limit the training program to instability-based resistance exercises. Because spinal stability is required for efficient execution of sports skills, a comprehensive program should include resistance exercises that involve a destabilizing com- ponent. The destabilizing component may involve instability devices, but can also be achieved with ground-based free weights that provide a destabilizing torque to the centre of gravity or a transverse stress to the core musculature. Spe- cific training of the core musculature should be periodized, just like any other component of athletic development. From a performance standpoint, unstable devices should not be utilized when hypertrophy, absolute strength, or power is the primary training goal, because force generation, power output, and movement velocity are impaired and may be in- sufficient to stimulate the desired adaptations, especially in trained athletes. Rehabilitation From a rehabilitation standpoint, the utilization of unsta- ble devices has been shown to be effective in decreasing 110 Appl. Physiol. Nutr. Metab. Vol. 35, 2010 Published by NRC Research Press
- 3. the incidence of low back pain and increasing the sensory efficiency of soft tissues that stabilize the knee and ankle joints. Such training may promote agonist–antagonist co- contractions with shorter latency periods, which allow for rapid stiffening and protection of joint complexes. These outcomes can provide some protection from injury or en- hance recovery from an injury to the core or elsewhere, and, therefore, can be included as part of an overall prehabi- lative or rehabilitative exercise program. General population For fitness and health conscious individuals and athletes at all levels (i.e., recreational to elite), ground-based free- weight lifts (e.g., back squats, dead lifts, Olympic lifts, and- lifts that involve trunk rotation) should form the foundation of exercises to train the core musculature. Such closed chain lifts are characterized by moderate levels of instability that allow for the simultaneous development of upper and lower extremity strength, thereby addressing all links in the kinetic chain. Closed chain exercises can also be implemented with instability devices incorporating lower loads. The instability- induced high core activation with lower force output can still provide sufficient stress on the system to induce or maintain health benefits; however, maximal strength or power development may be compromised. Open chain isola- tion exercises for the core musculature (e.g., trunk flexion supported on either a stable or unstable surface) might be most useful for localized muscular endurance development or for aesthetic-related goals (e.g., bodybuilding). Develop- ment of power, absolute strength, or localized muscular en- durance can potentially contribute to increased spinal stability if incorporated through the specific practice of rele- vant sports skills. Individuals who are training for health-re- lated fitness, or who cannot access or are less interested in the training stresses associated with ground-based free- weight lifts, can also receive beneficial resistance training adaptations with instability devices and exercises to achieve functional health benefits. Conclusion Ground-based free-weight lifts are highly recommended for athletic conditioning of the core musculature because they can provide the moderately unstable environments to augment core and limb muscle activation while still provid- ing maximal or near maximal force and power outputs. However, the concept of periodization illustrates the need to modulate volumes and intensities of training over time; thus, during phases involving lower loads, instability training de- vices and exercises can stimulate high muscle activation. Based on the relatively high proportion of type I fibers, the core musculature might respond particularly well to multiple sets that involve many repetitions (e.g., >15 per set). How- ever, the characteristics of a given sport may necessitate rep- etition ranges that emphasize strength and power development (e.g., <6 per set). References Abenhaim, L., Rossignol, M., Valat, J.P., Nordin, M., Avouac, B., Blotman, F., et al. 2000. The role of activity in the therapeutic management of back pain. Report of the International Paris Task Force on Back Pain. Spine (Phila Pa 1976), 25(Suppl. 4): 1S–33S. PMID:10707404. Anderson, K.G., and Behm, D.G. 2004. Maintenance of EMG ac- tivity and loss of force output with instability. J. Strength Cond. Res. 18(3): 637–640. doi:doi:10.1519/1533-4287(2004) 18<637:MOEAAL>2.0.CO;2. PMID:10707404. Anderson, K., and Behm, D.G. 2005. Trunk muscle activity in- creases with unstable squat movements. Can. J. Appl. Physiol. 30(1): 33–45. PMID:15855681. 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