Why performance athletes should avoid unstable surface training

Poor Training Methodologies: Unstable Surfaces

One of the most misguided ways that speed/power athletes can train is by using unstable surfaces. In a gym setting, unstable surfaces usually come in the form of BOSU balls, exercise balls, and balance boards. Uneducated athletes and trainers will often perform weight training exercises such as squats, lunges, deadlifting and even pressing variations while standing or kneeling on these unstable surfaces. In a lot of cases, the athlete will even perform the exercises unilaterally (i.e. standing on one leg) in order to further decrease stability during the exercise. The thought process behind doing this is that the unstable surface creates a more “functional exercise” by throwing the athlete off-balance and forces the athlete to increase the activation of “core” and stabilizer muscles. However, as we will outline below, this is one of the worst ways to train when it comes to strength and power development.

The importance of external load and intensity

In order for an athlete to become stronger, faster, or more powerful, an athlete must progress in intensity.  In strength & conditioning, “intensity” is defined as a percentage of maximum load or velocity. Therefore, for a workout to be classified as “high-intensity”, the work you do needs to be upwards of 95-100% of the 1RM in a particular lift, or 95-100% of the maximum velocity you can sprint. Anything outside of these percentages is, by definition, not high-intensity. Intensity does NOT equate to ratings of perceived exertion (RPE) during a particular exercise (how difficult the exercise feels), or outward signs of fatigue. 

Therefore, for an athlete to become stronger in the weight room, he or she must successfully lift an external load (i.e. weight) that is heavier than what they have ever lifted before, or in the case of power development, they must perform the exercise with a faster rate of force development (RFD)  – that is, more powerfully – than ever before. Likewise, if an athlete is training for speed, they must sprint at a velocity that is faster than they have ever run before. This ensures that the human organism is appropriately stressed, and has a reason to positively adapt and supercompensate. Conversely, if the exercise does not meet a minimum threshold of intensity, the human organism does not have a reason to adapt and the athlete will not improve.

How unstable surfaces hinder force production

Unstable surfaces greatly decrease the level of intensity that an athlete can train at by decreasing the external load that an athlete can lift, and this has overwhelming support when doing a quick search through strength and conditioning literature.  Behm et al (2002) found that force production decreased as much as 70% when using an unstable surface compared to a stable surface, and Kohler et al (2010) found little supporting evidence for the use of unstable surfaces or loads due to the decreases in force production. Chulvi-Medrano et al (2010) found that the use of instability devices does not increase performance during the deadlift.  McBride et al (2010) found that unstable surfaces decreased the amount of load used in squatting exercises, and recommended against their use due to the potential to limit physiological adaptation. Not limited to the lower body, Saeterbakken & Fimland (2013) found an inferior effect of unstable surfaces on muscle activation and strength during bench pressing. This list of refuting evidence against unstable surface training goes on and on.

Opportunity cost and Risk

Another important consideration when choosing which exercises to use with an athlete is the opportunity cost; how beneficial is the exercise, how much time will it take to coach or perform, and is there another exercise that could be used instead that might lead to faster performance enhancements in the same amount of time? Even if there was some merit to doing single leg squats on a BOSU ball with 25lb dumbbells in hand, wouldn’t we get a greater physiological adaptation by doing a barbell squat on solid ground with even a pedestrian 135lbs on the bar?

Also in the opportunity cost analysis is the determination of the inherent risk of an exercise. One of the main objectives of a strength coach is to take measures in training that will mitigate the risk and likelihood of injury during training or competition.  In that light, training with unstable surfaces can greatly increase the risk of acute injury due to the inherent instability of the exercises. Anecdotally, I have heard horror stories of a trainer who had a young athlete stand on a soccer ball because it was “functional balance training,” only to have the athlete fall off and break his ankle. Needless to say, sometimes unstable surface training is just not worth the risk it presents.

Conclusion

In conclusion, using unstable surfaces when training is one of the poorest training methods when attempting to develop strength and power in an athletes.  Unstable surfaces greatly decrease the intensity of training by limiting the external load that can be used. This ultimately prevents the athlete from getting stronger and faster because the ability to progressively overload the exercise and stress the human organism (which is crucial for positive adaptation) is greatly diminished.

The acronym BOSU stands for “both sides up,” meaning that the exercise tool can be used with the athlete standing on either the dome side, or the flat side up.  However, with unstable surface training clearly being inferior to stable surface training, “BOSU” might as well stand for “both sides useless.”

How to enhance recovery via low-intensity exercise

Introduction

In his book “Training Systems,” Charlie Francis defines recovery or regeneration to be the: continuous management of muscle tension/spasm, accelerated removal of the effects of fatigue, rapid restoration of body energy systems and substrates, and improved ability to renew physical activity without wasting unnecessarily the energy of the athletes. Low-intensity aerobic exercise, or sub-maximal exercise, for recovery purposes can be implemented in a variety of ways including running, biking, or swimming. This recovery strategy has the ability to attenuate some of the negative effects of fatigue via its circulatory effects and may aid in maintaining or improving performance in subsequent bouts of high-intensity exercise. Determinants of the type of exercise chosen, it’s volume, and intensity, will be contingent on the demands of the sport and the individual status of the athlete game-to-game.

Mechanism #1: Lactate Clearance

In order to discuss the mechanisms of action behind the recovery benefits of low-intensity aerobic exercise, we must first understand the acute effects of high-intensity exercise that may temporarily hinder performance. During anaerobic glycolysis, lactate accumulates as a by-product of ATP re-synthesis. This accumulation of lactate results in an increase in hydrogen ions and metabolic acidosis, which negatively affects the excitation-coupling process within a muscle cell thereby decreasing its ability to produce force. As a result, this accumulation of lactate must be cleared in order to maintain an athlete’s performance capabilities.

Lactate is removed via oxidation, which can occur at the muscle site where it is produced, or it can be transported via the blood to be oxidized in other muscle cells. Lactate can also be removed via the Cori cycle, where it is transported to the liver to be converted to glycogen. Therefore, the increased activity of the cardiovascular and pulmonary systems during low intensity exercise accelerate lactate clearance and recovery by delivering more oxygen and transporting lactate around the body’s cells for oxidation.

Mechanism #2: Reduction in Muscle Soreness

Another response to high-intensity exercise is delayed onset muscle soreness (DOMS). DOMS is caused by the eccentric component of exercise, which causes tearing and micro-trauma within a muscle cell, and a corresponding perceived level of pain within the athlete due to the resulting inflammation.  This pain and microtrauma reduces both the range of motion and contractile strength of a muscle.  As a result, the damaged muscle cells must be repaired in order to restore optimal function. Protein synthesis and skeletal muscle repair is a process that requires the delivery of both nutrients and hormones, which are delivered via the circulatory system. Therefore, the elevated heart rate and blood flow that occurs as a result of low-intensity exercise may aid the recovery process by increasing the rate of delivery of nutrients and anabolic hormones to the affected skeletal muscle.

Mechanism #3: Enhanced Circulatory System

Lastly, these circulatory effects are augmented by physiological adaptations that occur as a result of low-intensity exercise.  Aerobic exercise has been shown to increase cardiac output and stroke volume  resulting in an increase in overall circulation.  Furthermore, long-term aerobic exercise increases the density of capillaries which act as the exchange sites for the diffusion of oxygen, nutrients, and waste.  Consequently, these chronic cardiovascular adaptations cumulatively enhance the rate at which the aforementioned recovery processes take place.

How to implement low-intensity training

As with any training modality, recovery or not, each athlete has a set of individual circumstances that will dictate what exercise prescription will elicit the most benefit for them. For example, a swimmer who is not used to the eccentric forces that are faced while running may obtain superior benefit from a pool tempo session as opposed to a field-based one. Contrary to this, a large football player would likely swim inefficiently resulting in a higher perceived effort relative to if they had completed a pool-workout in shallow water or an on-field tempo workout. Therefore, when considering implementing the following modes of low-intensity aerobic exercise it is important to consider the physiological status of the athlete, their training history, injury status, skills, and training demands.

Extensive tempo running, if implemented correctly, can facilitate recovery. This exercise consists of athletes running intervals that are “performed strictly in the aerobic energy zone [which] promotes general fitness development and recovery via circulatory mechanisms,” (Hansen 2014). This training can often be completed on a field to allow for easy prescription and tracking of volume. However, if various circumstances such as weather, size of athlete or their preferences, or injury may preclude the use of a field, the same concepts can be applied to completing a workout on a stationary bike or treadmill and using time as the measurement of work:rest as opposed to distance.

As an alternative to land-based workouts, athletes and coaches can opt to facilitate recovery in a pool. This option has that added benefit of hydrostatic pressure which “may be beneficial in reducing the symptoms of muscle damage and general fatigue,” (Joyce, 2014). Furthermore, as water is weight bearing, impact on the lower extremities is reduced relative to running which may be beneficial for larger athletes or injured athletes. A typical pool recovery session may incorporate calisthenics and dynamic motions such as water jogging, knee lifts, side-shuffles, and lunges in the shallow end of the pool in addition to swimming lengths at an easy pace.

As alluded to earlier, intensity must be manipulated in a way that is conducive for recovery. A sprint coach, of runners or swimmers, may use a percentage of best time for a given distance (Francis, 2008 & Lomax, 2012). Specifically, Hansen suggests that “…coaches and athletes shoot for a 60-65% effort to be on the safe side, particularly for newcomers to the technique who have yet to find their tempo ‘groove’,” (Hansen, 2014). This is congruent with findings by Lomax who found that 20 minutes of swimming intervals at 65% of maximum velocity resulted in an approximate 82% reduction in blood lactate levels (2012). This method is only valuable to athletes in sports where time is the standard measurement of performance.

The efficacy of this method of recovery, like any training, is partially contingent on if it is practical to implement and how it is implemented. Although this type of recovery modality can be extremely useful, one must make sure to keep the goal of recovery in mind and not let excessive volume or intensity creep into the sessions: “excessive use of intensive tempo workouts can result in excessive fatigue, overtraining, blunted recovery and central nervous system disruptions if the volume is too high or sessions are too frequent,” (Hansen, 2014). Furthermore, sometimes athletes do not have access to the required facility or they simply lack the energy to complete even a light workout. In these instances, alternative recovery strategies should be sought out.

Conclusion

High-intensity training sessions, where an athlete is producing maximum forces and velocities, are necessary for positive physiological adaptations.  However, these high-intensity sessions elicit acute effects that temporarily impair performance.  These negative effects include central and peripheral fatigue, muscle damage, the accumulation of lactate, and the depletion of energy stores.  As a result, it is imperative for an athlete to facilitate the recovery process in order to attenuate these adverse effects prior to subsequent training sessions or competition. Low-intensity exercise provides a viable active recovery measure that augments the natural regenerative processes in the body.  Namely, low-intensity aerobic exercise increases both circulation and capillary density, which aids in the delivery of nutrients and elimination of waste from skeletal muscle cells. This type of recovery can be implemented in multiple ways and the chosen mode should be representative of the needs of the athlete as it relates to familiarity, physiological status post-game, and availability of facilities. It seems that approximately 65% of best time or effort is an appropriate level of intensity with volume being contingent on the training status of the athlete and demands of the sport. Furthermore, athletes and coaches alike must keep the goal of recovery in mind and resist increasing intensity or they risk perpetuating fatigue as opposed to attenuating it.

Special thanks to Kit Wong, MKin, CSCS for his contribution to this article.  Kit was a colleague of mine at SFU, and a fellow graduate student at UBC. He is currently the IST Lead and Head Strength Coach for Canada Cycling and the National Men’s Field Hockey Team.