The Tribune

By DR. KENT L. BAZARD

Sports Medicine Physician

Last week, in Part One of this series, we discussed one of the most common questions I hear from injured athletes: “Doc, when can I play again?” We established that return to sport should not be viewed simply as a date on the calendar.

An athlete progresses from injury through rehabilitation, return to participation, return to sport and, ultimately, return to performance. This week, we move to the next logical question. If the athlete is feeling better, the swelling has resolved and the pain is gone, how do we actually determine whether the body is ready for what sport is about to demand?

Imagine a 17-year-old sprinter recovering from a hamstring strain. Six weeks later, he walks normally, has no pain, demonstrates full range of motion and can jog comfortably.

On routine examination, everything appears encouraging. Ask him how he feels and the answer may be, “Doc, I feel 100 percent.”

Now suppose we objectively measure his hamstring strength and discover that the previously injured side remains substantially weaker during eccentric contraction. Or we progressively increase his running speed and discover that he becomes apprehensive as he approaches maximal velocity. He may feel recovered during everyday life, but sprinting is not everyday life. That difference is at the heart of modern return-to-sport testing. The clinical examination remains essential, but it answers only part of the question.

Pain, swelling, joint stability and range of motion tell us important things about recovery. They do not necessarily tell us whether an athlete has recovered the strength, power, speed, endurance, movement control and sport-specific capacity necessary for competition.

This is why I like to think of return-to-sport assessment as a progression from clinical recovery to physical capacity, functional performance, sport specific ability and finally performance readiness.

The first level is still the traditional medical assessment. Is there pain? Is swelling present? Has range of motion returned? Is the joint stable? Is the tissue responding appropriately to loading? Are there neurological findings or other clinical concerns?

Depending on the injury, imaging may also contribute. These findings help determine whether it is appropriate to progress. But passing the clinical examination should not automatically mean walking out of the office with unrestricted clearance.

The next question is capacity: what can the recovering body actually produce? Strength testing is one of our most useful tools here. Traditionally, clinicians have relied heavily on manual muscle testing.

That remains useful, particularly for identifying significant weakness, but the human hand is not a precision measuring instrument. Once an athlete becomes reasonably strong, relatively important differences can become difficult to appreciate manually.

Dynamometry allows us to quantify force production and compare limbs, muscle groups and serial measurements over time. At Empire Sports Medicine & Performance, for example, we can use the VALD Dynamo system to objectively assess force during different movements. Instead of documenting that knee extension is simply “strong,” we can measure how much force the athlete produces. Instead of saying that the injured leg “feels almost the same” as the other side, we can quantify the difference.

Most importantly, we can repeat the test during rehabilitation and determine whether the athlete is actually progressing. Hamstring injuries provide an excellent example. The hamstrings are not simply responsible for bending the knee. During sprinting they are exposed to very high forces, particularly while functioning eccentrically producing force while lengthening. An athlete may therefore demonstrate reasonable strength during a basic examination and still lack the eccentric capacity required for high-speed running.

Systems such as the VALD NordBord allow us to quantify eccentric hamstring force and compare the athlete's limbs. For the recurrent hamstring athlete, that can provide information that symptoms alone cannot.

However, this brings us to one of the most misunderstood numbers in return-to-sport testing: limb symmetry. A common approach is to compare the injured limb with the uninjured limb. If the recovering side approaches the performance of the opposite side, that is generally reassuring.

You will sometimes hear 90 percent symmetry used as a return-to-sport benchmark in certain testing batteries. But the number should never be interpreted in isolation. Imagine an athlete who injures the right knee and spends several months with substantially reduced training. During that time, the supposedly “good” left leg also becomes weaker. Eventually the right leg produces 900 Newtons of force and the left produces 950.

The athlete appears relatively symmetrical. But what if before injury each leg could produce considerably more? We may have achieved symmetry because both legs are now weaker. This is why symmetry is useful, but not synonymous with readiness. Where available, pre-injury baseline testing is extremely valuable.

Previous testing, sport-specific expectations, absolute force production, body mass and the athlete's training history can all add context. We should not allow one percentage to become a magical pass-or-fail number.

The same principle becomes even more interesting when we examine power. An athlete can regain strength yet still struggle to produce force quickly. Sport rarely gives us unlimited time to generate force. A sprinter leaving the blocks, a basketball player jumping for a rebound or a football player changing direction must produce large forces within very short periods. This is where measurements such as impulse and rate of force development can become clinically interesting.

The question moves beyond simply “How much force can you produce?” to “How quickly can you produce it, and how do you produce it?” Force-plate testing illustrates this beautifully. Consider two basketball players who both perform a 24-inch countermovement jump. If we only measure jump height, we may conclude that their performances are identical.

But the force-time curves underneath those jumps may tell very different stories. One athlete may efficiently absorb force during the downward phase and rapidly transition into propulsion. Another may take longer to develop force, shift loading toward one limb or use a different movement strategy to achieve the same final height.

The result can look the same while the strategy used to produce it is very different. This is one reason force plates have become increasingly valuable in sports performance and rehabilitation environments.

They can help us examine characteristics such as force production, impulse, eccentric braking and interlimb loading strategies. They do not independently determine whether an athlete is safe to play, but they can reveal aspects of performance that our eyes and a simple jump-height measurement may miss. Functional testing takes us another step closer to sport. Following lower-limb injuries, clinicians may use tests such as the single-leg hop, triple hop, crossover hop, timed hop or lateral hopping tasks.

These tests require the athlete to integrate strength, balance, coordination and confidence into movement. But once again, distance alone does not tell the whole story. An athlete may hop a respectable distance while landing stiffly, shifting the trunk excessively or spending very little time on the recovering leg. A stopwatch and measuring tape can tell us what happened.

Watching the movement can help tell us how it happened. Movement quality therefore matters. I want to see how an athlete squats, lands, decelerates and controls the body on one leg. Depending on the sport and injury, we may assess cutting and change of direction. Does the knee collapse inward under load?

Does the athlete unload one side? Is trunk control lost during a single-leg task? Does the athlete require several small corrective steps to regain balance? These observations become particularly important as movement becomes faster and less predictable. Then comes speed. A sprinter cannot be cleared for sprinting based solely on strength testing.

A football or soccer player cannot be fully assessed without running, accelerating, decelerating and changing direction. A basketball player needs to demonstrate explosive movement in multiple planes.

Timing systems such as DASHR allow us to objectively measure acceleration and sprint performance rather than relying on the observation that the athlete “looks fast again.”

And this is where return-to-sport testing should increasingly resemble the sport itself. For the sprinter recovering from a hamstring injury, progression might move from controlled running to acceleration, higher-speed running and eventually maximal-velocity exposure.

For basketball, we may progress from bilateral jumping to single-leg tasks, landing, planned changes of direction and eventually reactive movement. For swimmers, shoulder strength and mobility must eventually be considered alongside stroke volume and race-intensity work.

For baseball and cricket athletes, shoulder capacity has to be integrated into a progressive throwing or bowling program. Each sport asks different questions of the body, so a generic clearance test cannot provide every answer. There is another factor that I believe clinicians and coaches sometimes underestimate: fatigue. An athlete may look excellent during the first few repetitions of a test.

But sport is rarely performed completely fresh. Basketball players must jump and change direction repeatedly. Footballers sprint, decelerate, tackle and then sprint again. A sprinter may have heats before a final. A swimmer may compete in multiple events. As fatigue develops, force production can fall and movement strategies may change. Suppose an athlete performs five excellent single-leg landings at the beginning of a session.

After repeated running, jumping and change-of-direction work, the same athlete begins landing with poorer trunk control and obvious asymmetry. Which version represents the athlete who will appear late in the game? Probably both. This is why later-stage rehabilitation must eventually expose athletes to appropriate fatigue.

It does not mean deliberately exhausting every injured athlete during every assessment. It means recognizing that the final stages of return to sport should progressively recreate the environment in which the athlete will actually perform.

Volume, intensity, complexity, unpredictability and fatigue all need to be reintroduced intelligently. There is also a limitation we should acknowledge. No return-to-sport test can tell us with certainty that an athlete will not be injured again. There is no force-plate number, hop distance, strength ratio or sprint time that provides immunity from injury. Sport is too complex, and injury is multifactorial.

Testing should therefore not be presented as a crystal ball. Its value is in identifying measurable deficits, monitoring progress and improving the quality of the decision. This is also why I prefer a battery of information rather than one test. Clinical examination tells us one part of the story. Strength testing tells us another. Functional movement adds another. Sport-specific performance adds another.

The athlete's symptoms, training tolerance and confidence provide additional pieces. The final decision emerges from the pattern rather than from a single green number on a report. For young athletes in particular, this is an important message for parents.

If your child has finished physiotherapy and is no longer in pain, that is excellent progress. But if the sport involves sprinting, jumping, cutting, throwing or contact, ask whether those qualities have actually been rebuilt. Rehabilitation should eventually prepare the child for the activity they are returning to, not merely for the activities of everyday life.

This is one of the areas where sports medicine and sports performance naturally overlap. At Empire Sports Medicine & Performance, objective testing allows us to follow an athlete beyond the examination table.

The medical question may initially be whether the injured tissue is recovering appropriately. As rehabilitation progresses, however, the questions become different: How strong is the athlete? How symmetrical? How powerful? How fast? Can they control the movement? Can they repeat it? Can they tolerate increasing workload? And eventually, can they perform? But even if every number looks good, there is one more variable we have not yet addressed. The athlete may still be afraid.

A player can regain strength and hesitate when asked to cut aggressively. A sprinter can produce excellent hamstring-force numbers and still refuse to open up at maximal velocity.

A basketball player can jump normally in testing but protect the previously injured leg when another player enters their landing space. And an athlete who has been injured repeatedly may interpret every sensation from the previously injured area as a warning that something is about to happen again.

That brings us to the final part of this series. Next week we will move beyond the testing room and onto the field, court, track and pool. We will examine psychological readiness, confidence, workload progression, fatigue, modified training and the crucial transition from being medically cleared to actually being ready to perform.

Because pain-free is an important milestone. It simply isn't the finish line.

Next week: The Road Back — Part 3: “Cleared to Play—But Are You Ready to Perform?”

Dr. Kent L. Bazard B.Sc., M.Sc. (Sports Medicine), MBBS