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Valgus knee: how effective are elastic mini-bands?

by P. Debraux | 14 November 2023

valgus, knee, mini-bands, elastic, resistance, hip rotators, muscles, movement, correction, squat, reactive neuromuscular training, science, sport, training

During exercises involving the lower limbs such as squats, lunges, deadlifts or vertical jumps, it's generally advisable to keep the knees "correctly" aligned with the hips, ankles and feet. Correct alignment generally means minimizing any inward or outward movement of the knees during the eccentric and concentric phases of the exercise. However, medial knee collapse, or valgus knee (i.e., knees moving inwards) has been identified as a fairly common fault during these exercises. And this could have an impact on long-term knee health, as research suggests that increased valgus knee increases the risk of sustaining a knee injury such as a ruptured anterior cruciate ligament (ACL), for example. Given this concern about potential risks, sports and health professionals have been looking for effective ways to remedy this type of movement when it occurs.

It has been suggested that the use of a mini elastic band around the thighs, just above the knees could be one way of solving this problem. By pushing the knees further into valgus knee and providing better proprioception at the thigh and hip, an elastic mini-band could help increase muscle activation of the hip's external rotators, which could then help bring the knees back into a more neutral alignment without a mini-band. In addition, the use of an elastic mini-band requires little instruction from the coach, as individuals responding to the resistance of the band can potentially improve their technique without additional supervision.

Several studies have presented mixed results regarding efficacy on the use of mini- bands for squat training, making it difficult to recommend best practice for exercise programs. Yet, despite the lack of clear scientific evidence to support their benefits, mini-bands wrapped around the thighs have gained popularity in rehabilitation, fitness and strength training circles. Conversely, some studies have criticized the use of mini-bands to correct valgus knee, arguing that they can actually increase the risk of knee injury during squat movements. But this argument is not supported by longitudinal studies either. In order to evaluate existing research on the use of mini-bands, a narrative review assessed existing studies on the effects of using elastic bands during squat movements, focusing specifically on muscle activity and lower limb kinematics. So what are the pros and cons of using elastic mini-bands to correct valgus knee?

What is dynamic valgus knee and why is it a problem?

Dynamic valgus knee is a movement in which an individual's knees move towards the midline of the body in the frontal plane during certain movements, particularly those involving squatting movements, such as squat, or during sudden changes of direction, as in team sports. In simpler terms, the knees are no longer aligned with the hips, ankles and feet, and show an inward displacement.

This phenomenon is potentially problematic for the long-term health of the knees, for several reasons:

Increased lateral compression and medial distraction: Misalignment during valgus knee results in greater compressive forces on the lateral compartment of the knee, and greater distraction forces (i.e., pulling the joint surfaces apart) on the medial compartment. This imbalance can put stress on the knee structure, leading to acute injuries or chronic conditions over time.

Stress on the anterior cruciate ligament (ACL): Valgus knee can significantly increase stress on the ACL. The ACL is responsible for preventing the tibia from sliding forward relative to the femur. When the knee moves towards the midline of the body, it creates a twisting motion at the knee joint, which increases the stress on the ACL and can lead to an ACL tear or rupture. Studies have shown that in female athletes, greater valgus knee in pre-season was associated with ACL ruptures during the competitive season. And correction of this valgus generally results in a reduced risk of ACL rupture...

Cartilage and meniscus wear: altered load distribution can lead to accelerated wear of the knee's cartilage and menisci (two pieces of cartilage that act as shock absorbers and guides in the knee), resulting in conditions such as osteoarthritis or meniscus tears.

Development of patellofemoral syndrome: valgus knee can also lead to misalignment of the femur and patella, which can cause pain in the knee behind the patella, particularly when sitting.

By overstressing certain structures, valgus knee can disrupt the delicate balance of forces that allow the knee to function properly, increasing the risk of injury and long-term damage.

What are the potential benefits and risks of using an elastic mini-band in squat movements?

The use of a mini-band in squat movements has been proposed as a technique to reduce dynamic valgus knee based on Reactive Neuromuscular Training (RNT) first evoked by Voight & Cook in 1996. Reactive neuromuscular training is a rehabilitation technique that incorporates reactive exercises that provide the individual with a kind of external cue to which he or she must respond in an attempt to achieve a certain movement or goal. The main objective of reactive neuromuscular training is to correct undesirable motor patterns or postures.

One way of implementing this method is to exaggerate an undesirable movement or posture using an external force. For example, if an individual exhibits valgus knee when squatting, an elastic mini-band placed around the thighs just above the knee can be used to bring the knees towards greater valgus. This will encourage the person to react and prevent the knees from moving closer together, thus promoting better knee alignment. By simultaneously improving recruitment of the hip abductors and external rotators, this technique could contribute to long-term correction of the motor pattern once external resistance is removed.

Most studies have shown that mini-bands increase the muscular activity of at least one muscle in the lower limbs. Among them, an increase in the activity of the gluteus maximus muscle (hip extensor, abductor and external rotator) has been reported in several studies. This supports the idea that the use of a mini-band can promote hip external rotation to improve knee alignment. However, some studies did not reveal substantial changes in muscle activity, suggesting that the effects may depend on specific factors such as the type of exercise performed and the level of resistance of the band.

However, the impact of mini-bands on knee alignment or valgus knee is unclear. Some studies have found a reduction in valgus knee when using mini elastic bands, suggesting an improvement in knee alignment. However, some research has shown that elastic bands can actually increase valgus knee during squat movements with mini-bands. Nevertheless, this effect seems to be more pronounced with mini-bands of greater resistance. If external resistance does indeed increase muscular activity in the hip's external rotators, the alignment correction that should follow will depend on how much force a person is actually able to deliver in hip external rotation during a squat movement. The resistance of the mini-band must therefore be correctly chosen for each individual. Because if used incorrectly, the band can potentially encourage incorrect technique, resulting in ineffective workouts and/or an increased risk of injury.

At present, results from the scientific literature on the effectiveness of elastic resistance on valgus knee are still quite limited, with mixed results. Further research is needed to fully understand the implications and best practices for their use. What is clear is that elastic bands can increase the workload of exercises by forcing individuals to produce an extra moment of force in hip external rotation. But as for their effects on knee alignment, the benefits are less often observed and, in some cases, mini-bands can even increase valgus knee.

The elastic band is a simple, cost-effective tool that requires minimal instruction from a trainer, making it a handy tool for independent training sessions. Therefore, if you decide to use a mini-band this way, it's advisable to choose lighter resistance and always make sure you're using the correct technique. If an increase in valgus knee is observed, it may be beneficial to switch to a lighter band or reconsider its use.

What are the research limitations?

Current research into the use of elastic mini-bands to correct valgus knee in squat movements has a number of limitations and shortcomings. Firstly, there is a paucity of research looking specifically at the effect of mini-bands on valgus knee during squat movements. This literature review listed nine such studies.

Secondly, none of the studies checked at the start of the protocol that the participants have valgus knee. This might suggest that if knee alignment is already almost perfect at the start of the study, it will be difficult to determine whether or not the use of an elastic band is effective in reducing valgus knee...

What's more, the use of an elastic mini-band in this literature has only been examined acutely (single-session studies). So, even if the participants in these studies had valgus knee at the start of the study (which they probably didn't, as indicated in the previous paragraph), the possible effects of using elastic bands were only quantified during a single session. To properly study the effects of mini-band training on valgus, it would therefore be necessary to observe chronic use over several weeks.

The aim of reactive neuromuscular training is to observe improvements in technique after the removal of external force, rather than to correct the movement pattern during its application. Thus, the fact that some studies have shown that elastic bands amplify valgus knee could be considered a positive result. However, it remains to be seen whether this exaggeration of valgus is detrimental or beneficial in the long term.

Key points to remember

The use of an elastic mini-band during squat movements could increase muscle activity in the hip abductors and external rotators, which could promote better knee placement. However, not all studies show a reduction in valgus knee. In some conditions, it may have no effect at all, while in others it may increase it. Whether or not this is beneficial for the user remains to be seen.

Due to the limitations of current research, it is difficult to make practical recommendations regarding the use of mini-band to help correct poor knee placement. But if someone decides to use this technique, they should use a light mini-band. Even light resistance elastic bands have been shown to improve hip external rotation muscle activity, and the risk of inducing a potentially undesirable increase in hip external rotation is reduced. However, it is advisable to carefully monitor an individual's knee alignment throughout the squat-based movement. In the event of a noticeable increase in valgus knee, the user should switch to a lighter band.

Reference

  1. Forman DA, Alizadeh S, Button DC, Holmes MW. The Use of Elastic Resistance Bands to Reduce Dynamic Knee Valgus in Squat-Based Movements: A Narrative Review. Int J Sports Phys Ther 18 (5) : 1206-1217, 2023.

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