Paul S. Glazier

The Big Idea

It’s GUT check time!  We are all familiar with this cliché in sports performance:  tests of gameness, courage, fortitude, stick-to-itiveness.   But less familiar is another meaning of GUT.  Beginning roughly in the late 1970s particle physicists began looking at the possibilities for the otherwise distinct three of the four forces in nature at high energy to merge into an indistinct single force.  They called this model a Grand Unified Theory, or GUT for short.

Over the years, this general idea of explaining how the universe works quite naturally metastasized into grand explanatory applications in smaller academic universes.  In this article from Human Movement Science (2015), the author proposes a GUT of sports performance.  What makes GUT attractive for understanding the universe of sports performance are the complex interacting variables common to it: such as, physiological fitness, tactical awareness, nutrition, biomechanical proficiency, history, psychosocial features, even genetics.  Unfortunately, when these variables are studied as distinct, not interacting phenomena, nothing particularly grand results.

Glazier rides the historical frustration within the sport sciences of how to integrate the many subdisciplines into effective interdisciplinary teaming.  Asking the right questions, solving complex problems, and improving sport performance and satisfaction are beyond the grasp of applied sport sciences taken individually.  Hence, GUT.


  • Sport performance is an inherently complex human action defined by interacting variables.
  • Yet the sciences of sport performance freelance independently, often competitively, with little effort to find common ground between them.
  • The time has arrived for the sciences of sport performance to reflect the lived experiences of sports themselves as self-organizing and interacting coordinated structures.
  • It is time for a Grand Unified Theory of sports performance, or GUT.
  • A framework long ago suggested (Newell 1986) but not taken up, is a constraints-based model where the patterns of control and coordination determining sport performance outcomes emerge from a confluence of interacting organismic, environmental, and task constraints.
  • Such a GUT could provide the self-organizing idea for collaborative interdisciplinary research.
  • A GUT for sport performance provides not only a cooperative model for study, but will also potentially benefit athletes, coaching practitioners and the relevance of applied sport scientists themselves.

The Research

A suggested unifying framework 

Glazier argues that there is a way bring together the variety of sport science voices into a genuine collaborative effort.  He proposes a constraints-based GUT.  The idea of a constraints model has been around for over 30 years (Newell, 1986).  But few since then have seen the potential for its grand unifying impact in the sport sciences.  Let’s briefly sketch Glazier’s line of thinking.

  • Constraints are either internal or external limitations or boundaries that restrict possible degrees of freedom spatially and/or temporally in complex, self-organizing systems.
  • There are organismic, environmental, and task constraints bearing on our individual, human movements.
  • Organismic constraints are largely imposed by our physiology, morphology, physicality, or psychology.
  • Environmental constraints are external to our movement degrees of freedom; some are simply ambient light, altitude, temperature, surfaces; others can be sociocultural such as peer groups, societal expectations; yet others even geographical location, such as competing at home or away.
  • Task constraints are specific to the undertaking, including rules, goals, practice rule modifications, even coaching instructions or cues.

GUT as a way of integrating subdisciplines of sport science

What emerges from the confluence of these interacting three constraint categories are patterns of coordination and control of sports performance.  Glazier outlines the various perspectives represented by the subdisciplines in becoming integrating partners in understanding and explaining sport performance.  Here are a few examples.

  • Sport biomechanics, sports performance analysis, and sports technology can provide the methods and tools for measuring and analyzing patterns of coordination and control.
  • Skill acquisition and motor control can enhance understanding how morphology changes during skill acquisition, and how practice design and training environment can be manipulated, or how complexity of human systems change across the lifespan of an athlete.
  • Sports physiology and sports psychology can provide methods and tools for measuring and analyzing important organismic constraints such as fatigue and anxiety.
  • Strength and conditioning can contribute to the development of structural organismic constraints by way of carefully devised and implemented training interventions.

As an example of the necessary integration of some of these interdisciplinary approaches, Glazier uses a rugby union match.  So, let’s say we wanted to understand exactly how a full back missed a crucial penalty kick in the closing moments of this match.  The short answer is: He choked!  But there’s much more to it than this.  It is necessary to examine the magnitude and direction of the force applied to the ball during impact.  This would be analyzed in relation to the key task (distance) and environmental (wind direction) constraints.  And too, we need to know how the degrees of freedom (e.g., muscles, joints, and segments) of the kicking leg were organized and how they interacted to produce that force.  Added to that, we would want to know how psychological constraints, such as anxiety, may have disrupted the organization and integration of these degrees of freedom.

Furthermore, if we wanted to learn why one rugby union team is more successful over the duration of a match or a season than another team, we would examine how degrees of freedom (i.e., players) were organized and how they interacted with one another in attacking or defending plays.  And too, we would want to know how the organization and interaction of degrees of freedom varied according to task (e.g., tactics) and environmental (e.g., weather conditions) constraints.  As well, we would need to learn how key physiological constraints, such as fatigue, impacted the organization and interaction of degrees of freedom.

The value of a GUT in sport performance

As a big idea, a GUT in sports performance isn’t a difficult idea to grasp.  All it intends to provide is a way of making the research design experiences consistent with the lived experiences of playing sports.  The call for a synergistic research effort by way of the constraint’s framework is sensible.  In no way does it minimize the power of individual subdisciplines; it energizes them.  Think of a seed crystal.  In chemistry the seed crystal is a small piece of single crystal put into a saturated or supersaturated solution to grow a large crystal.  The large crystal grows around the seed crystal.  And in short time crystallization happens.  This may not be the best analogy, but in a sense the interacting constraints model (organismic, environmental, and tasks) is the seed; what crystalizes are the emerging patterns of coordination and control that largely determine the sport performances and outcomes.

Glazier identifies a few valued results from synchronizing sport performance research and applied practices.  This constraints-based GUT could be used to:

  • Nurture interdisciplinary research collaborations
  • Break down the existing sub-disciplinary silos
  • Restore greater disciplinary balance to the field of sport performance research
  • Promote a more holistic understanding of sports performance at all levels of analysis
  • Increase the explanatory power of applied research work
  • Provide a stronger rationale for data collection and variable selection
  • Direct the development of integrated performance monitoring technologies
  • And, improve the scientific rigor for integrating the sub-disciplines of sport science in applied sport science support programs at all levels of play

Concluding comment

One way of looking at Glazier’s advocacy is that he is throwing down the gauntlet.  Not issuing a demand for knock down duels between contesting sub-disciplines.  But he is certainly challenging researchers, practitioners, and players alike to bring their individual programs and prejudices into better collective alignment.  Instead of perpetually maneuvering for influence, it is much better for all to situate themselves into flowing confluence.  And to do this, Glazier implies, to really do this sincerely, and to welcome a GUT for performance sports, takes nothing else—but guts!

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