I think that most triathletes and runners think that their ability to move functionally (think snatch squats dropping below a parallel thigh position) has little to do with their ability to swim, cycle and run over longer distances because these movements require little in terms of mobility or balance or coordination beyond that which nearly any adult human, who is not currently injured, possesses.    Consequently, we devote the vast majority of our time to swimming, cycling and running (particularly cycling 😉 and presume our limits to performance speed come from limits to our training volume and/or genetic limitations on energy production (one has a low VO2max), never even considering the general ability to move as relevant.

Contrary to that idea, those of us who teach and coach swimming often begin to realize over time that individuals  who cannot reach full flexion through the shoulder girdle (extend their arms in the air together and behind their head) seem to have more trouble creating a long and effective swimming stroke and consequently can’t swim as fast.  Those coaches/teachers who are most enlightened then often try to improve this mobility limitation in some way as a way to make it possible to improve swimming technique.

In running and cycling the need for functional movement ability seems even less likely to be meaningful in limiting performance and may even contribute in some ways to improved movement efficiency.    Think tight hip flexors creating an early stretch reflex response during hip extension to recover the foot quickly in running.   One of my college roommates at the U. of Arizona, Keith Englke, participated in one of first experimental studies of this concept, whereby they used stretching to improve the hip extension range in runners and found that this approach actually reduced their stride frequency and made their physiological economy worse (they needed more oxygen to run the same speed).   https://academic.oup.com/ptj/article-abstract/73/7/468/2729171

However, as our definition of functional movement has evolved, simple range of motion my not be the only or even the main factor of importance in movement competency.   Beyond this narrow mobility view, the idea of movement compensation has emerged as possibly the most powerful aspect of functional movement ability.   For those not yet versed in this thought process, compensatory movements occur in certain joints when other joints fail to perform their duties in a given movement pattern.   As an example think of the typical post race running photo where you are inevitably caught while in support (one foot on the ground – see above).   In the best runners the pelvis dips only slightly on the non-support side and the rest of the lower and upper body maintain fairly vertical alignment.     In many of us however, the non-supported side of the pelvis drops a few more degrees and pitches forward a few degrees , causing the knee to move inward and rotate, and the support foot to flatten and point outward (pronation) excessively.   All of these compensatory movements place greater stress on the associated joints and clearly predispose us to joint injures and/or overuse syndromes – such as  runners knee and plantar fasciitis.   However, these compensatory joint actions can also be thought of as a source of inefficiency, allowing the energy the body captures from gravity and returns to forward movement via elasticity to be lost or “leaked” away with each step taken.   The analogy I like is of a spring which has lost some of its optimal tension so that when a load is applied the spring collapses too much reducing the energy it can return elastically.

One enlightened physical therapist/strength and conditioning guru, Grey Cook, realized more than twenty years ago that we needed a systematic way to measure/evaluate the occurrence of compensation and movement competency and created an approach now called the Functional Movement Screen (FMS).   His test is based on the performance of seven movement patterns which focus to a greater or lesser degree on core to limb joint mobility (think hips and shoulder girdles), appropriate core activation (both statically and dynamically) and the integration of the two into challenging movement patterns which are most relevant to gait (think snatch squat, step over and lunge patterns).   Each pattern is scored from 0-3 as follows:   (3 pts) can complete the movement successfully without compensation, (2 pts) can complete the movement successfully with compensation, (1) cannot complete the movement (0) the movement causes significant joint pain suggesting injury.

Over the years an emerging body of research makes it clear that in many human activities, having low movement ability as measured by the FMS is associated with a greater occurrence of injury.  https://journals.sagepub.com/doi/full/10.1177/0363546516641937   Note – this does not mean that one can predict injury solely from the FMS score, just as one cannot expect to predict a heart attack solely from a cholesterol score.    Rather, it means that how well you can move is probably one in many factors that predispose a person to injury, so odds of injury increase when you move poorly.

However, the available research has never shown that movement ability as measured by the FMS is even moderately related to performance outcomes. https://journals.lww.com/nsca-jscr/fulltext/2014/12000/Efficacy_of_the_Functional_Movement_Screen___A.34.aspx

Why?   This seems illogical, at least to me.  If differences in movement ability associate with differences in injury occurrence why do they not also relate to differences in the ability to perform?    One only need review the three most typical descriptive studies examining this question to know why.    Each uses a smallish homogeneous sample population, typically a collegiate athletic team, whereby the athletes vary to a relatively small degree in their athletic performance.   Contrast this to actual humans who vary hugely in athletic performance (think the difference between winning times and last finishing times in a triathlon for instance).  In addition, such research sample groups typically vary minimally in movement ability as measured by the FMS as well.   In thinking about how relationships are measured mathematically via correlation, basically the computations address the similarity in ways that the two measures rank those measured across each scale of measurement used.   When everybody measured falls within a narrow band on the scale for both measures being evaluated the chances for ranking congruence go down greatly, meaning it is difficult to find relationships mathematically.

This situation bothered me so I set out to do an experimental study in which I would attempt to improve movement ability, as measured by FMS, while controlling for other factors which we know affect running performance such as running training load and strength/power training, and then see if running performance would also improve.   We selected a population we thought would be low on movement ability in the first place, recreationally competitive runners (as opposed to sub elite/elite athletes), thereby allowing room for improvement in the first place.

We found that our treatment group improved both FMS score and 1 mile running performance with no change in strength, power or training load, while the control group did not change in any of our measures.   https://www.researchgate.net/profile/George_Dallam/publication/331526978_FMS_Corrective_Intervention_Improves_FMS_Composite_Score_and_1-Mile_Run_Time_without_Concurrent_Change_in_Hip_Extension_Strength_Vertical_Jump_or_T-Shuttle_Run_Time_in_Recreational_Runners/links/5c8038ea458515831f8b1378/FMS-Corrective-Intervention-Improves-FMS-Composite-Score-and-1-Mile-Run-Time-without-Concurrent-Change-in-Hip-Extension-Strength-Vertical-Jump-or-T-Shuttle-Run-Time-in-Recreational-Runners.pdf

The intervention followed the ideas developed by Grey Cook himself.   Essentially, we used the FMS to identify compensations and then focused individually on each subject to improve their compensatory movements by improving the specific mobility, core control and integration components specific to each pattern in which they were deficient.   This approach was led by undergraduate students using a relatively simple process that any coach or trainer might apply.

The long and short of the study, in my mind, is that while training, strength/power and genetic ability drive most of what differentiates us in triathlon running ability, poor movement ability begins to act as a drag on performance ability if compensatory movement patterns are present or emerge (it happens to all of us 😉 resulting in lower FMS scores.   As most adult recreational endurance athletes exhibit multiple compensatory movement patterns (think race photos and low starting FMS scores of our subjects and those in other studies of runners) this concept has nearly universal application in triathlon.  If you are coaching or teaching triathletes and/or runners you might want to consider adding the FMS and an approach for reducing compensatory movement to your arsenal of skills.

As to the presence of compensation in the athletes pictured  above.  Clearly and not so much ;-).