Updated: 10/16/26
Essential Points:
What Is Unstable Surface Training? Unstable surface training (UST) uses equipment such as foam pads, balance boards, and BOSU balls to challenge postural control, coordination, and the integration of sensory information.
Benefits and Limitations: UST can improve certain measures of balance and increase muscle activation during specific exercises. However, it may limit force production and is not necessarily superior to stable surface training for building strength, power, or functional performance.
Who Benefits Most? UST may be useful for older adults, rehabilitation patients, and certain athletes when applied appropriately. However, it should complement, rather than replace, traditional strength training, functional exercises, and task-specific balance training.
Unstable surface training (UST), otherwise known as unstable balance training or instability training, has sparked an ongoing debate in the health and fitness community. Some argue it’s a game-changer for improving balance, proprioception, and injury prevention, while others see it as an unnecessary or even detrimental form of training when compared to traditional exercises on stable surfaces.
In this definitive guide, we’ll explore UST from every angle: what it is, how it works, its benefits, limitations, and practical applications for everyone from athletes to older adults.
What Is Unstable Surface Training?
Unstable surface training (UST) involves performing exercises on surfaces that provide instability, such as Bosu balls, Swiss balls, balance boards, foam pads, hedgehogs, and various obstacle course implements.
The idea behind it is that by challenging your body’s ability to stabilize, you engage more muscles, especially stabilizer muscles, and improve neuromuscular control. Stabilizer muscles, for the purpose of this article, are considered to be the smaller muscles that stabilize joints and allow proper movement patterns (although are not always small muscles). Prime movers, which we will be discussing a few times, are the larger muscles such as the chest muscles or large leg muscles that facilitate movement throughout your environment.
But does UST live up to the hype? Let’s start by understanding how UST affects your body at a physiological level.
The Physiology Behind Unstable Surface Training
The body’s reaction to unstable surfaces is largely driven by the need to maintain balance. After all we never want to fall down if we can avoid it. When you stand or perform exercises on an unstable surface, your central nervous system (brain and spinal cord) and three bodily balance systems (vision, vestibular, somatosensation) work overtime to keep you upright. This involves constant feedback from your muscles, tendons, joints, and ligaments to maintain posture and prevent you from falling.
If you don’t know the three systems of balance yet, I highly encourage you to read this article here for a better global understanding.
Increased Muscle Activation
EMG (electromyography) studies have demonstrated that unstable surface training can increase muscle activation during certain exercises, although the effects vary depending on the muscles being measured, exercise performed, and type of unstable surface used. (1, 2, 3)
For example, a 2020 study found that half-squats performed on a BOSU resulted in significantly higher activation of the vastus lateralis, vastus medialis, and biceps femoris, compared to a standard half-squat on the floor. (4)
It’s important to note that EMG levels do not directly translate to force output, but rather the amount of electrical activity being directed to a muscle. (5) So although the EMG activity in the biceps femoris (a part of the hamstring) is more activated during a half-squat on a BOSU, that does not mean it is generating more force than during a heavy loaded half-squat, only that it is generating more activation compared to a similarly loaded stable half-squat. The amount of load that is being lifted has a significant impact on the amount of muscle that can be gained.
This increase in EMG activation isn’t limited to the lower body. Upper body exercises performed on unstable surfaces, such as push-ups on a stability ball, have shown increased core activation, particularly in the rectus abdominis and obliques. (6) However, this comes with a trade-off in the form of reduced force output of the prime movers (chest and shoulders) compared to standard versions of the exercises such as the floor push-up.
Challenging Proprioception
Proprioception is your body's ability to sense its position and movement in space. (7) It plays an important role in balance, coordination, and injury prevention.
Unstable surface training challenges the nervous system to continuously adjust to changes in the support surface, requiring the integration of sensory information to maintain balance.
Although, challenging proprioception does not necessarily mean improving proprioceptive accuracy.
Research suggests that unstable surfaces may encourage sensory reweighting, or changes in how the brain prioritizes different sources of sensory information, rather than directly improving proprioception at an individual joint. (8, 9, 10) These adaptations may contribute to improvements in balance and postural control, although the extent to which they transfer to other activities depends on the task being trained.
For example, you may have seen blue foam pads commonly used in physical therapy clinics. These are simple tools that allow clinicians to manipulate the support surface and challenge an individual's ability to maintain balance. By making somatosensory information from the feet and ankles less reliable, foam surfaces can encourage greater reliance on other available sensory information.
Research suggests that foam-based balance training can improve certain measures of balance in older adults. (11) When performed with appropriate supervision, guarding, and support, these exercises provide a controlled environment for practicing balance while minimizing unnecessary fall risk.
It’s important to note that unstable surfaces are not inherently superior to stable surfaces, and their use should be based on the individual's abilities, rehabilitation goals, and safety needs.
Types of Balance Strategies
When it comes to maintaining balance, your body uses several strategies, depending on the challenge posed by the surface or external forces. (12) These strategies include the ankle strategy, hip strategy, and, in extreme cases, the stepping strategy.
Ankle Strategy: Used during small perturbations, the ankle muscles make small adjustments to keep the body balanced. This is typically the first line of defense and is most commonly employed when standing on relatively stable surfaces or during minor instability. During normal daily standing, we utilize this strategy to stay relatively still.
Hip Strategy: When instability increases, your hips come into play. This strategy involves larger movements at the hip joint to realign the center of mass over the base of support. For example, during exercises like single-leg stands on a balance board, you’re more likely to rely on this strategy as the instability increases. In real life, this may come into play if you are suddenly bumped into by someone while standing talking to your friends.
Stepping Strategy: In more extreme instability situations, where the ankle and hip strategies aren't enough, the body may initiate a stepping strategy, where you take a step to regain balance. This type of strategy occurs when you get knocked out of your base of support and begin the process of falling but are able to stop an actual fall.
If you want to learn more about these strategies, including two additional strategies, click here.
Balance Strategy on Unstable Surfaces
Unstable surface training can challenge multiple postural control strategies, including ankle and hip strategies.
The strategies used depend on factors such as the support surface, direction and magnitude of the disturbance, sensory information available, and the individual's experience with the task. (13)
As individuals become more familiar with an unstable surface, their movement patterns and reliance on different sensory inputs can change. These adaptations can improve their ability to control posture during the practiced activity. But, balance strategies do not necessarily progress through a fixed sequence, and improved performance on one unstable surface does not guarantee equivalent improvements in every real-world balance challenge.
The Debate on Unstable Surface Training in Sports Performance
UST is a hotly debated topic in sports performance circles. Advocates argue that using tools like BOSU balls, wobble boards, or balance discs improves proprioception, core stability, and neuromuscular control, critical components for injury prevention and athleticism. They believe that conditioning athletes to stay balanced in unstable environments helps them react better to off-balance moments during competition.
Many performance coaches question whether these benefits translate effectively to real-world sports movements.
One key critique is that UST lowers the amount of force an athlete can produce, which is true as we will see further down in this article. For example, squatting on a wobble board significantly reduces the weight an athlete can lift safely, limiting their ability to build the strength and power needed for explosive movements like sprinting or jumping.
Another argument against UST is that it doesn’t accurately replicate the dynamic instability athletes experience in sports. Most coaches follow the SAID Principle (Specific Adaptations to Imposed Demands), or rather if you want to get better at an activity you must do the activity. Coaches often prefer ground-based exercises, like agility drills and plyometric training, that better mimic the demands of competition. Research on UST is also mixed. While the research shows improvements in balance, evidence supporting meaningful improvements in athletic performance remains limited.
Ultimately, UST can still play a role in injury prevention or rehabilitation, but many coaches reserve it for warm-ups or supplemental work. The debate highlights a broader question: Should training prioritize force production and sport-specificity, or emphasize functional balance and stability? For now, most experts agree that UST works best as one tool in a larger, well-rounded training program.
Benefits of Unstable Surface Training
Although controversy surrounds UST, it does have benefits:
1. Improved Balance and Coordination
One of the most widely recognized benefits of UST is its potential to improve balance and postural control. (14, 15, 16) By challenging individuals to maintain stability under changing conditions, these exercises can encourage improvements in movement coordination and the integration of sensory information. This may be particularly useful for older adults or individuals recovering from injury. Just remember, improvements in balance test performance should not automatically be interpreted as reductions in actual falls, as these are different outcomes.
2. Increased Core Stability
Because UST challenges your body’s ability to stay upright, your core muscles are often working overtime. Numerous studies have shown increased EMG activity in the transversus abdominis, multifidus, and obliques during UST. (17) Core stability is essential for everything from maintaining proper posture to potentially reducing lower back pain and enhancing athletic performance.
3. Injury Prevention
Balance and neuromuscular training can play an important role in certain injury prevention programs, particularly those addressing ankle sprains and lower extremity injuries. (18, 19, 20, 21) Unstable surface exercises may be useful components of these programs by challenging postural control, joint positioning, and coordination.
But, increased muscle activation or improved balance performance does not automatically translate to a lower injury rate. Many successful injury prevention programs incorporate multiple training methods, including strength training, landing mechanics, balance exercises, and sport-specific movement practice. Consequently, unstable surface training should be considered one potential component of injury prevention rather than a standalone solution.
4. Enhanced Functional Fitness
UST may have applications for functional fitness, particularly when activities involve maintaining balance on changing or uneven surfaces. Examples include hiking on uneven terrain or participating in activities such as surfing, snowboarding, or skiing. But, whether improvements from unstable surface exercises transfer to these activities depends on the similarity between the training task and the actual activity.
Research on functional training more broadly highlights the importance of matching exercises to the movements and abilities an individual wants to improve. (22, 23, 24)
UST can simulate these real-world conditions more closely than exercises performed on a stable surface. Of course practicing the goal activity is always better than simulating with an unstable surface, as the more specific an exercise is, the more it will improve the goal activity.
Limitations of Unstable Surface Training
While UST offers numerous benefits, it’s important to understand its limitations to avoid overestimating its value:
1. Reduced Force Output
One of the biggest criticisms of UST is that it limits your ability to generate maximal force. (19, 25) For example, a squat performed on a BOSU ball engages more stabilizer muscles but significantly reduces your ability to lift heavy weights. Studies show that UST exercises activate stabilizers at the expense of prime movers, like the glutes and quadriceps. This makes UST suboptimal for building maximal strength and hypertrophy.
2. Lower Transfer to Traditional Strength Training
Research indicates that while UST improves balance and stabilizer activation, it has limited carryover to traditional strength training exercises. (9, 19) If your goal is to improve maximal strength or power (e.g., for lifting heavier in a deadlift or sprinting faster), UST should not replace traditional training methods. Strength gains from unstable surface exercises are often modest compared to those achieved with stable, heavy-load training.
3. Potential Risk of Injury
Like any exercise modality, unstable surface training carries potential risks when the difficulty exceeds an individual's abilities or when appropriate safety precautions are not taken. The unstable nature of these exercises can increase the likelihood of losing balance, particularly when combined with heavy loads, complex movements, or excessive fatigue.
Yet, this does not mean unstable surface training is inherently dangerous. The goal should be to match the difficulty of the exercise to the individual, provide appropriate support when needed, and progress gradually.
For individuals at increased risk of falling, exercises should be performed near stable support or under appropriate supervision. Ultimately, the potential benefits of any exercise should justify the risks involved.
4. Limited Applicability for Some Populations
For individuals looking to maximize strength, power, speed, or aesthetics UST might not offer significant benefits. (9, 19, 24) Powerlifters, Olympic weightlifters, sprinters, and bodybuilders for example, may not find much value in UST since their performance is based on generating maximal force output on stable surfaces. Additionally, these athletes most often already have a good base of stability and control.
5. Overemphasis on Balance vs. Strength
For individuals who are untrained or focus primarily on balance due to the difficulty of it, there is a risk of overemphasizing balance training at the expense of foundational strength. This is especially problematic when UST replaces foundational exercises like squats, deadlifts, or lunges, which are crucial for overall strength development. Additionally, while balance is key for healthy aging, it must be matched with equal amounts of useable strength. A proper training plan should always be implemented.
Practical Applications: Who Can Benefit from Unstable Surface Training?
1. Older Adults
Older adults may benefit from unstable surface training when it is appropriately incorporated into a comprehensive balance and exercise program. Research has demonstrated improvements in certain measures of dynamic balance following unstable surface training, including responses to unexpected balance disturbances. (16)
Even so, it is important to distinguish improvements in balance performance from reductions in actual falls.
Strong evidence supports balance and functional exercise programs for reducing falls in older adults, but the evidence is less definitive regarding unstable surface training specifically. (26) Exercises performed on foam pads or other unstable surfaces may be useful additions to a fall prevention program, but they should complement activities such as strength training, functional movements, stepping reactions, and other balance challenges rather than replace them.
2. Rehabilitation and Physical Therapy
UST is frequently incorporated into rehabilitation programs, particularly for individuals recovering from ankle injuries or experiencing deficits in balance and postural control. (9, 19) These exercises can provide a graded challenge to the neuromuscular system and may help individuals develop better control during specific balance tasks.
For example, a rehabilitation program might incorporate single-leg standing on a foam pad or balance disc when appropriate for the individual's condition and ability. But, these exercises should not automatically replace progressive strengthening, functional movement training, or other rehabilitation interventions.
The decision to use an unstable surface should be based on the intended training adaptation rather than the assumption that a more difficult surface is always better.
3. Athletes in Specific Sports
Athletes participating in sports requiring balance, agility, and rapid changes of direction may benefit from certain forms of unstable surface training. (27) These exercises can provide an additional challenge to postural control and coordination, particularly when the training demands are relevant to the athlete's sport.
Nevertheless, improvements in balance on an unstable surface do not necessarily translate directly to better sports performance.
For most athletes, traditional strength training, plyometrics, agility drills, and sport-specific practice should remain the foundation of their training. Unstable surface exercises may serve as a useful supplement when there is a clear reason to include them.
4. General Population
For the average person, UST can add variety to a workout and provide functional fitness benefits if optimal function and balance is a goal. (19) In doing so, it should complement, rather than replace, traditional strength and conditioning exercises.
Best Practices for Incorporating Unstable Surface Training
To maximize the benefits of UST while minimizing its limitations, follow these best practices:
Use UST as a Supplement: Incorporate UST as part of a balanced workout routine, but don’t rely on it as the sole form of training. Combine it with traditional strength training and cardiovascular training for maximum results. Use this form of training as part of a warm-up, active rest, cool-down, or just for a fun variety session.
Focus on Form: Proper form is critical during UST. Start with basic exercises and only progress to more complex movements when you can maintain decent form and you have a specific reason for it. Proper form in this context means generally stable and showing no excessive losses of position.
Don’t Overdo It: UST should be used sparingly, especially when training for strength or hypertrophy. For example, incorporate UST into your routine 1-2 times per week, or for a short time during warm-ups or cool downs, depending on your goals and fitness level. Of course, if you enjoy unstable balance training you may do it as much as you’d like.
Choose the Right Surface: Different unstable surfaces provide varying levels of challenge and stimulus. Start with lower to the ground, and generally less challenging surfaces like foam pads or air discs, and gradually progress to higher and more unstable surfaces like BOSU balls or slacklines. Compare this to going up in weight on a exercise, you need to start slow to prevent injury and improve your overall skills.
Progression in Unstable Surface Training
If you want to incorporate UST into a structured workout program, understanding how to progress is key. Progression should be gradual and based on your current fitness level, goals, and experience with balance training.
Phase 1: Mastering Stability on Stable Surfaces
Before progressing to UST, it’s crucial to first master exercises on stable surfaces. For example, a beginner should be able to squat with decent form on a flat, stable floor before attempting to squat on a balance board or BOSU ball. Proper form ensures that you’re targeting the correct muscles and avoiding compensatory movements that could lead to injury.
Phase 2: Introduce Light Instability
Once you’ve mastered basic movements, you can begin introducing light instability. Start with simple balance exercises, such as single-leg stands or lunges on a foam pad or soft surface. Progressively challenge yourself by using more unstable surfaces like a Bosu ball or wobble board.
Phase 3: Incorporate Instability with Load
As you become more proficient, you can begin to add light weights to your unstable surface exercises. For example, performing a single-leg squat while holding dumbbells on a balance board will further challenge your stability. However, it's important not to overload the movement, as heavy weights on unstable surfaces can compromise form and increase injury risk.
It is also important to understand the “why” behind the exercise. For most individuals this type of progression is of little real world use, and has limited practical application.
Phase 4: Advanced Dynamic Movements
In this phase, you can begin incorporating advanced, dynamic movements on unstable surfaces. Plyometric exercises, such as lateral hops onto a BOSU ball, or single-leg deadlifts on a wobble board, can be added for athletes looking to improve sports performance if it mimics athletic activities. It’s important to ensure that proper form is maintained throughout these movements, as the risk of injury can increase with more complex exercises.
Again, there should be a specific intent and reason for this level of UST training. The risk of injury may outweigh the benefits to sports performance, and greater difficulty does not automatically produce greater benefits.
Final Thoughts: Is Unstable Surface Training Right for You?
Unstable surface training is a valuable tool that can improve balance, postural control, and muscular stability in the right context. It’s particularly useful for older adults, individuals recovering from injury, and athletes looking to improve agility and coordination in specific sports.
However, UST should not be seen as a replacement for traditional strength training, and you should always have a reason for the exercise you are doing. Its limitations in terms of force output and muscle activation make it a suboptimal choice for those whose primary goals are strength, power, hypertrophy, or aesthetics. Additionally, the risk of injury at higher levels of difficulty usually is not worth the reward for the average person.
Make sure to check your programs and ensure that UST is not overutilized, while knowing that some form of UST may be beneficial in the warm-up, cool-downs, or as a break from traditional training. If you're interested in functional fitness, injury prevention, or improving balance and coordination, UST can play an important role in your training regimen.
But like any tool in fitness, it’s best used in moderation, in combination with other training modalities, and with specific intention for the most well-rounded results.
What’s Your Fall Risk Score?
Most people don’t notice their balance declining until something goes wrong.
This 10-minute self-assessment will show you:
• How stable your balance really is
• Where you're most at risk (strength, coordination, or falling ability)
• What to focus on first
No equipment. No guesswork. Just clear answers.
References
Kaur N, Bhanot K, Ferreira G. Lower extremity and trunk electromyographic muscle activity during performance of the Y-Balance test on stable and unstable surfaces. International Journal of Sports Physical Therapy. 2022;17(3). doi:10.26603/001c.32593
De Amorim Batista G, Beltrán SP, Passos MHPD, Calixtre LB, De Holanda Santos LR, De Araújo RC. Comparison of the Electromyography Activity during Exercises with Stable and Unstable Surfaces: A Systematic Review and Meta-Analysis. Sports. 2024;12(4):111. doi:10.3390/sports12040111
Tan F, Harput G, Ulusoy B, Guney-Deniz H. The influence of unstable surfaces on ankle muscle activation during functional exercises. Journal of Bodywork and Movement Therapies. 2024;40:602-609. doi:10.1016/j.jbmt.2024.05.006
Buscà B, Aguilera-Castells J, Arboix-Alió J, Miró A, Fort-Vanmeerhaeghe A, Peña J. Influence of the amount of instability on the leg muscle activity during a loaded free barbell Half-Squat. International Journal of Environmental Research and Public Health. 2020;17(21):8046. doi:10.3390/ijerph17218046
Hug F, Hodges PW, Tucker K. Muscle force cannot be directly inferred from muscle activation: illustrated by the proposed imbalance of force between the vastus medialis and vastus lateralis in people with patellofemoral pain. Journal of Orthopaedic and Sports Physical Therapy. 2015;45(5):360-365. doi:10.2519/jospt.2015.5905
Anderson GS, Gaetz M, Holzmann M, Twist P. Comparison of EMG activity during stable and unstable push-up protocols. European Journal of Sport Science. 2011;13(1):42-48. doi:10.1080/17461391.2011.577240
Dean JC. Proprioceptive feedback and preferred patterns of human movement. Exercise and Sport Sciences Reviews. 2012;41(1):36-43. doi:10.1097/jes.0b013e3182724bb0
Glass SC, Wisneski KA. Effect of Instability Training on Compensatory Muscle Activation during Perturbation Challenge in Young Adults. Journal of Functional Morphology and Kinesiology. 2023;8(3):136. doi:10.3390/jfmk8030136
Behm D, Colado JC. THE EFFECTIVENESS OF RESISTANCE TRAINING USING UNSTABLE SURFACES AND DEVICES FOR REHABILITATION. Published April 1, 2012. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3325639/
Kiers H, Brumagne S, Van Dieën J, Van Der Wees P, Vanhees L. Ankle proprioception is not targeted by exercises on an unstable surface. European Journal of Applied Physiology. 2011;112(4):1577-1585. doi:10.1007/s00421-011-2124-8
Hirase T, Inokuchi S, Matsusaka N, Okita M. Effects of a balance training program using a foam rubber pad in Community-Based Older adults. Journal of Geriatric Physical Therapy. 2014;38(2):62-70. doi:10.1519/jpt.0000000000000023
Biomechanics and motor control of human movement. Google Books. https://books.google.com/books?hl=en&lr=&id=_bFHL08IWfwC&oi=fnd&pg=PR13&ots=JoiAarebU5&sig=BWZNqFWNDlzeSZQgKTtRwf7luPo#v=onepage&q&f=false
Van Dieën JH, Van Leeuwen M, Faber GS. Learning to balance on one leg: motor strategy and sensory weighting. Journal of Neurophysiology. 2015;114(5):2967-2982. doi:10.1152/jn.00434.2015
Blasco JM, Tolsada C, Beltrán M, Momparler AM, Sanchiz-Benavente R, Hernández-Guillen D. Instability training, assessing the impact of level of difficulty on balance: A randomized clinical trial. Gait & Posture. 2019;70:116-121. doi:10.1016/j.gaitpost.2019.02.029
Lee J, Chun MH, Lee J. The effect of a gait and balance training program on an unstable mudflats surface in older adults: A randomized controlled pilot study. Medicine. 2023;102(12):e33272. doi:10.1097/md.0000000000033272
Rizzato A, Bozzato M, Rotundo L, et al. Multimodal training protocols on unstable rather than stable surfaces better improve dynamic balance ability in older adults. European Review of Aging and Physical Activity. 2024;21(1). doi:10.1186/s11556-024-00353-8
Behm DG, Drinkwater EJ, Willardson JM, Cowley PM. Canadian Society for Exercise Physiology position stand: The use of instability to train the core in athletic and nonathletic conditioning. Applied Physiology Nutrition and Metabolism. 2010;35(1):109-112. doi:10.1139/h09-128
McKeon PO, Hertel J. Systematic Review of Postural Control and Lateral Ankle Instability, Part II: Is balance training clinically effective? Journal of Athletic Training. 2008;43(3):305-315. doi:10.4085/1062-6050-43.3.305
Behm DG, Sanchez JCC. Instability resistance training across the exercise continuum. Sports Health a Multidisciplinary Approach. 2013;5(6):500-503. doi:10.1177/1941738113477815
Padua DA, DiStefano LJ, Hewett TE, et al. National Athletic Trainers’ Association Position Statement: Prevention of Anterior Cruciate Ligament Injury. Journal of Athletic Training. 2018;53(1):5-19. doi:10.4085/1062-6050-99-16
Rivera MJ, Winkelmann ZK, Powden CJ, Games KE. Proprioceptive Training for the Prevention of Ankle Sprains: An Evidence-Based Review. Journal of Athletic Training. 2017;52(11):1065-1067. doi:10.4085/1062-6050-52.11.16
Liu CJ, Shiroy DM, Jones LY, Clark DO. Systematic review of functional training on muscle strength, physical functioning, and activities of daily living in older adults. European Review of Aging and Physical Activity. 2014;11(2):95-106. doi:10.1007/s11556-014-0144-1
Xiao W, Soh KG, Wazir MRWN, et al. Effect of functional training on physical fitness among athletes: A Systematic review. Frontiers in Physiology. 2021;12. doi:10.3389/fphys.2021.738878
Horn J. Instability Functional Training: Evidence-Based Recommendations for Coaches. Research Directs in Strength and Performance. 2023;3(1). doi:10.53520/rdsp2023.10561
Behm DG, Drinkwater EJ, Willardson JM, Cowley PM. The use of instability to train the core musculature. Applied Physiology Nutrition and Metabolism. 2010;35(1):91-108. doi:10.1139/h09-127
Sherrington C, Fairhall NJ, Wallbank GK, et al. Exercise for preventing falls in older people living in the community. Cochrane Database Syst Rev. 2019;1(1). doi:10.1002/14651858.CD012424.pub2
Gao J, Abdullah BB, Dev RDO, Guo Q, Lin X. Effect of instability Resistance training on sports performance among Athletes: A Systematic review. Published September 3, 2023. https://www.rpd-online.com/index.php/rpd/article/view/1455
