Many of the reporting strategies I have mentioned previously have encouraged athlete use of the GymAware for immediate motivation, and enabled medium- to long-term athlete tracking and program assessment. In this article, I would like to present a few strategies that may assist with specific injury rehabilitation, injury reduction through the identification of asymmetry. For these reasons, the use of the GymAware for identifying and reducing asymmetry is possibly the most encouraging aspect for the athletes.
I use GymAware in single leg exercises such as leg curl, single-leg leg press or step-ups to assess bilateral asymmetry
What is an asymmetry?
Lower body asymmetry has been examined in several ways within the literature and strength and conditioning professionals are generally concerned with any is a difference in output between the right and left legs. The most commonly reported methods to investigate lower limb asymmetry have been jumping and hopping, either vertical jumping or horizontal [2, 4, 5]. Isokinetic methods are also common, but often not easily accessible .
Although it is widely acknowledged that the presence of bilateral asymmetry (a discrepancy in measurable performance between left and right limbs, either in centimetres jumped vertically or horizontally, or force or power output as measured by gym based or laboratory based exercise tests) in elite athletes is undesirable and recognised as a precursor to injury, the literature is yet to provide a conclusive figure on what represents imbalance and several studies have cited 10-15% as an observed range in athletes [3, 4].
For further information, I would suggest the following references:
▪ Hewit, J., Cronin, J. and Hume, P. Multi-directional leg asymmetry assessment in sport. Strength and Conditioning Journal. ahead of print – 2012.
▪ Newton, R.U., Gerber, A., Nimphius, S., Shim, J.K., Doan, B.K., Robertson, M., Pearson, D.R., Craig, B.W., Hakkinen, K. and Kraemer, W. Determination of Functional Strength Imbalance of the Lower Extremities. Journal of Strength and Conditioning Research. 20: 971-977. 2006.
I use GymAware in single leg exercises such as leg curl, single-leg leg press or step-ups to assess bilateral asymmetry. Practically in the gym, when performing a unilateral exercise, it is not ideal to have an athlete perform reps on one leg, wait to change the GymAware selection to the other side (right or left) and then continue. Therefore, when I am working with my athletes, I ask them to complete all of the prescribed reps (for example, 3 on each side) on the right side, and then all the reps on their left. I then know that the first half of the set (reps 1 to 3) is the right side and the second half (reps 4 to 6) is the left. The outcome is a graph such as Figure 1. In Figure 2 the graph is of an athlete who demonstrates a limb dominance as opposed to an imbalance due to injury. Nonetheless, this would require further assessment and intervention.
Editors note. You can also compare selected sets directly on the online application.
Fig 1. When working with my athletes, I ask them to complete all of the prescribed reps (for example, 3 on each side) on the right side, and then all the reps on their left
Fig 2. This graph is of an athlete who demonstrates a limb dominance as opposed to an imbalance due to injury
Previously these graphs used to be created after the session on the GymAware website. Now with the new iTouch apps, you can create a similar graph immediately on the gym floor and provide this sort of feedback to your athletes. I have found another useful function is the “Percentage of Best” which is a variable that can be selected to show real-time results. Although all reps are calculated based on the first rep, all I want to see is that the difference between their left and right is within the commonly referred to 10% figure. One set outside this range may be due to technique or effort, but if it is consistently outside this range, a more thorough analysis is required. What is excellent about this function, is that after a few trials and working with the athlete, they quickly understand the process and can monitor it themselves during the session.
As the coach, I am able to then continue coaching the entire group (10-30 players depending on the session) and can review the performance later and make changes to the program for the next session. Whether that involves additional repetitions, sets, or supplementary exercises depends on the specific circumstances. For feedback, whether you use the graph or percentage function may depend on which form your athlete understands best – do they decipher pictures better than numbers? All athletes are different so I try both and see which they respond to best.
A more thorough analysis
With consistent imbalance, or athletes returning from a significant lower body injury that has affected their lower body training for several months, I assess each limb more thoroughly. I have found that within a short time frame, an athlete returning from long-term injury can regain a reasonably balanced strength level (as measured by a repetition maximum test). However, it has been interesting to observe the load-power curve of each leg independently as they can be different between the previously injured leg and non-injured leg. This can be seen in Figure 3. Here, the athlete is able to lift the same external load with their left and right legs.
However, you can see that the power produced by each leg is very different. I have added error bars at 5% to show the magnitude of the difference. Although the error bars are not entirely precise (but it gives an indication), if the bars do not overlap, then there is roughly a 10% difference between limbs and requires attention.These forms of analysis require a bit more time than the previous styles of analysis I have mentioned in earlier articles, but I believe them to be very important. Also, these are only produced for those athletes identified, which may be between 10 to 20% of a squad.
Here, the athlete is able to lift the same external load with their left and right legs. However, you can see that the power produced by each leg is very different.
Training to improve Asymmetry
From my experience, the first step in overcoming asymmetry is to identify it. This may sound rather unsophisticated, but using this form of feedback with athletes can have a profound effect on reducing asymmetry. In many cases, maximum strength has not been the issue, but rather the ability to move a given load with similar effort, or velocity, between sides. Therefore, training at sub maximal loads, mindful of the target, has been a relatively successful strategy to date.
There are many possible reasons for the presence of asymmetry which require thorough investigation. In close consultation with the medical team I work with, a frequent strategy (amongst others) has been to slowly bridge the gap in imbalance starting from a position of balance. When training athletes with asymmetry, we are essentially trying to bring the lines on the graph closer together. We start at the point of divergence (where the error bars no longer meet, in this example, 100kg) and that is our maximum load and we train with the range of loads up to this maximum until the gap closes. Once that is achieved, we can increase the load and work on closing the next gap in the curve.
As stated, I have primarily used this strategy to assess imbalance with single limb performance in leg press and step-ups. I have used it sometimes for other areas such as leg curl for left and right hamstring imbalance. It could be further applied to upper body exercises such as lat pulldown or a cable chest press perhaps, if these were important areas of imbalance for upper body dominant sports such as water polo or swimming. The main points for using a GymAware in this area is to regularly monitor your athletes, have a process to be able to further analyse any asymmetry and put in place strategies to rectify the imbalance. Part of your strategy should involve collaboration with peers as overcoming symmetry may be multi-factorial. Identifying and overcoming any imbalances is a very encouraging training process for athletes and a very rewarding one. Hopefully you find some of this information useful for your athletes.For more articles from Brendyn Appleby go here.
1. Croisier, J.-L., Forthomme, B., Namurios, M-H, Vanderthommen, M. and Crielaard, J-M. Hamstring Muscle Strain Recurrence and Strength Performance Disorders.The American Journal of Sports Medicine. 30: 199 – 203. 2002.
2. Hewit, J., Cronin, J. and Hume, P. Multi-directional leg asymmetry assessment in sport.Strength and Conditioning Journal. ahead of print – update. 2012.
3. Hoffman, J.R., Ratamess, N.A., Klatt, M., Faigenbaum, A.D. and Kang, J. Do Bilateral Power Deficits Influence Direction-Specific Movement Patterns? Research in Sports Medicine. 15: 125-132. 2007.
4. Maulder, P., and Cronin, J. Horizontal and vertical jump assessment: reliability, symmetry, discriminative and predictive ability.Physical Therapy in Sport. 6: 74-82. 2005.
5. Newton, R.U., Gerber, A., Nimphius, S., Shim, J.K., Doan, B.K., Robertson, M., Pearson, D.R., Craig, B.W., Hakkinen, K. and Kraemer, W. Determination of Functional Strength Imbalance of the Lower Extremities.Journal of Strength and Conditioning Research. 20: 971-977. 2006.
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