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Sportlight Conversation: John Grace

John Grace, performance coach interim director of performance for Major League Soccer’s Chicago Fire, has been a performance coach with the club since January 2020. His focus lies on player development, analyzing the force-velocity profiles of players and comparing those figures within the club and across the league. The former head of sports science with Orlando City SC and former director of performance for the Orlando Pride, Grace also serves as an advising consultant for Sportlight Technology.



As an advisor to Sportlight, what do you consider to be your role and primary contributions?

I have the pleasure of assisting Sportlight in some of its sport-science-related endeavors, as well as its market strategy for the MLS and U.S.-based sports. There is a tremendous team at Sportlight, and sometimes you just need people in the trenches to give advice on what works and what doesn’t.


Some of the questions for which I’ve tried to provide some insight include:

  • What are the pain points of a professional staff with current hardware and software?

  • How can the product further assist in informing decisions?

  • What are some strategies to penetrate the U.S. market and MLS specifically?


It has been challenging, although very interesting, because these can be difficult questions that require reflection and strategic consideration. These types of questions pave the way for product development, and also allow me to create a clear road map to where I may want to see the product grow in the future.


In your Twitter feed, you recently posted: “When mentioning hamstring strength and risk of injury, one major aspect that is not taken into consideration is the athlete’s maximum speed capacity. Bigger engine = more risk.” How can player tracking systems best aid performance practitioners in this area?

As maximal sprint speed increases, maximal hamstring strength would need to increase to balance the musculotendon unit, as well as support the velocity of the lower limb in the late swing phase. If the tendon is too stiff or the muscle too strong, we may see an increase or repeat in muscle strains. So one of the key indicators of hamstring health that we can monitor is athlete exposure to high relative velocities. This has become increasingly popular as a strategy to prepare athletes and decrease risk of injury. In my research, I have made two anecdotal observations that would somewhat contradict the current conventional knowledge in field-based sports:


First, the number of exposures may not be as high as past research would lead us to believe. I find that even 1-3 exposures per week (matches included) seem to provide sufficiently specific and high tension as to reduce athlete injury risk. (Of course, if our goal is to add horsepower – and not just polish – to the Ferrari, we would most likely need more dedicated sprint volume.)


Second, I don’t believe the duration between maximal exposures is as short as past research would indicate for risk reduction. In my experience, this is even more true when an athlete is consistently in the weight room complementing training with other structural stimuli.


Research typically mentions “exposures per week” as a metric to aim for when preparing the athlete. This makes some sense from a research perspective, but humans don’t “reset” at the beginning of a new week. Rather, think of loading on a rolling calendar – and, more specifically, a rolling calendar with exponentially decaying physical qualities. This means that as more days accumulate without a given stimulus, a given physical quality will begin to diminish – and, at some point, begin to decay quickly. Sometimes our job is to simply provide the correct stimulus, at the right time, before major decay occurs. Each quality also has a specific decay period, and it seems that hamstring preparedness comes in around 14 days, depending on the player. With most clubs’ training schedules being so chaotic, player tracking systems allow for the rather easy monitoring of these exposure factors in each athlete.


What do you envision as the future of player tracking?

The obvious future of player tracking, I think, is hardware. I don’t think players will be wearing GPS units for much longer. In the NBA and major Division I university programs, this is already happening. Even for outdoor venues, this will eventually become the standard.


What is missing from player tracking units at the moment is context. Gone are the days when practitioners believed covering more distance was “better.” Longer running distances – rather than being a direct objective – are simply a measure of the outcome of tactics, technical play, score line, player profile, weather, surface, etc. I conducted an unpublished analysis of a couple years’ worth of our club matches and found no correlation between any running metric and points earned from a match. This confirms that the volume of running doesn’t dictate the outcome of the match. Rather, the context of the match dictates the physical output of the players.


Consider: If a player is out of position, whether attacking or defending, they will most likely run more – and typically at a faster speed, to adjust for initial poor positioning. If this occurs many times in a single match, this could result in a higher volume and intensity of running. If the player’s poor positioning is corrected, it will typically result in less running.


Less running due to better field position is a positive outcome, as it may conserve energy. For players, this conserved energy may result in:

1. Improved late-match performance when a match requires tapping into conserved energy

2. Less localized muscle damage and fatigue when the match doesn’t require use of conserved energy, which should improve recovery timelines


This examples don’t encapsulate the full potential of player tracking, but we need to understand context before we can expect technology to solve difficult performance problems. Blending GPS data with technical and tactical information will allow for an improved understanding of specific game models and the particular physical requirements needed to improve individual players within a system.


In your experience, how has technology influenced Major League Soccer?

Tech has had a large influence in MLS. Most league teams now have fully dedicated analytics departments and dedicated sports science professionals. For many, analytics plays a big role in preparation from week to week. Data retrieval leads to insights that allow a club to better prepare for an opponent’s offensive tactics and strengths, while sharpening its ability to exploit weaknesses or certain areas of the pitch.


Outside of match analytics and deeper in-game statistics, the most common piece of technology that teams have access to is a GPS system. As mentioned, GPS has helped some teams in aspects of physical training stress management as well as post-injury rehab management. When used appropriately, tech can help provide an edge. But if every other team is using the same system and has access to the same data, the playing field is leveled. The edge then becomes how you leverage that technology to enhance decision making. Clubs that hire excellent staff and equip them with the most accurate technology are able to make better decisions more frequently – and have the highest chance of long-term success.


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