A common question I hear is whether or not the Strength Deficit (SD) is the same as the Eccentric Utilization Ratio (EUR). For context, they both are the same test, which includes comparing the Counter Movement Jump (CMJ) to the Non-Counter Movement Jump (NCMJ) Ratio, but the difference is the decision we make is what makes EUR and SD different. It is the same assessment, but it is testing for two different things.
The difference between SD and EUR is that SD has a separate half of the assessment that EUR does not. The idea of EUR is to look at the difference between CMJ and NCMJ to determine the utilization of the stretch-shortening cycle. SD looks at the impact of jumping with and without the contribution of the stretch-shortening cycle. In terms of Strength Deficit, the larger the difference, the larger the Deficit. alternatively, the smaller the difference the smaller the Deficit.
Large Deficit > 1.25 (CMJ: NCMJ)
Small Deficit < 1.1 (CMJ: NCMJ)
Strength Deficit, compared to EUR, is the value of understanding that not all athletes need to utilize and therefore develop the stretch-shortening cycle. The assumption is that every athlete needs to become more powerful and display higher peak forces combined with faster rates of peak force. The means of developing a higher peak force or rate of peak force is not exclusive to utilizing the stretch-shortening cycle. Creating higher force at faster rates without a preceding stretch-shortening cycle is the benefit of looking at SD.
The idea is that the stretch-shortening cycle is universally valuable. There are several situations where producing power from a static position and not being able to leverage a stretch-shortening cycle before contraction is beneficial. The distinction is important because it devalues NCMJ as a proxy for potential performance. Anecdotally think about the higher body mass positions like an offensive or defensive lineman CMJ performance. It is always impressive to see a 300lb plus athlete jump over 30”, but it is not a direct KPI. There are innumerable examples of an offensive lineman having a sub 20” CMJ doing extremely well.
The key behind Strength Deficit is the weight of NCMJ and CMJ relative to the sport or positional demands within the sport. It is a peaking strategy or Sports Specific Physical preparation (SPP) model. SD reverse engineers the training to meet the outcome. If someone needs to create a Smaller Deficit, concentric training becomes the priority. If someone needs to create a Larger Deficit, eccentric training becomes the priority.
The principle of Specificity states we will be the product of what we repeatedly do. More importantly, we are the product of what we repeatedly focus on and emphasize. A Smaller Deficit Athlete needs to enhance NCMJ and power without the stretch-shortening cycle. If we exclusively look at EUR, we miss that. We will myopically focus on developing only through utilizing the stretch-shortening cycle. We run the risk of a program that is not specific to the needs as well as doing more than the system is capable of recovering from.
This is my blog and my thoughts. Of course, I am biased into thinking that EUR is different than SD. If you are reading this, you probably understand that I am writing firsthand from my experience and knowledge. There is always a bias and agenda attached to something done and created. The strength of Strength Deficit is reframing your training decisions’ logic. Blindly improving a metric without regards to its correspondence to its objective is bad training. Having assessments such as Strength Deficit that provide a continuum to follow is positive for training decisions. Any bias or agenda included is diminished from the positive aspects of adhering to that bias and agenda to greater net outcomes.
McGuigan MR, Doyle TL, Newton M, Edwards DJ, Nimphius S, Newton RU. Eccentric utilization ratio: effect of sport and phase of training. J Strength Cond Res. 2006;20(4):992-995. doi:10.1519/R-19165.1