Sports biomechanics: return to activity after an injury

For both, always with a doctor's recommendation. It is also suitable for anyone who practises sport as a hobby and wants to get back to running or playing with greater confidence.

At the end of rehabilitation, when there is no longer any pain and sports clearance is about to be decided.

No. Running and gait analysis is performed by Podiatry. Here, the strength and function of the injured area are measured.

It is not enough for the pain to have stopped or for the expected weeks to have passed: return to activity is decided by criteria, not by the calendar. The criteria used include recovering full mobility, tolerating strength training and progressive running without pain during or after, and ensuring the strength of the injured side is similar to that of the uninjured side; a difference in strength between legs is a factor to consider, although on its own it does not predict a relapse. Biomechanical testing measures mobility and strength and compares them with the uninjured side, so that the sports clearance decision is backed by data.

The limb symmetry index (LSI) is the percentage of strength, or jump performance, of the injured side compared to the uninjured side. The most widely used threshold to authorise return to play is 90% or higher, particularly in knee injuries measured with isokinetic dynamometry, but recent evidence insists that it should not be used in isolation, but alongside functional tests, tissue healing time, and the athlete's confidence. For this reason, the report does not provide an automatic 'fit' status: it describes the measurements and what still remains to be recovered, and the decision is made by the doctor or physiotherapist managing your recovery with that data in hand.

It is a strength test in which the device maintains a constant movement speed and measures the force applied at each degree of the range of motion. It allows the injured side to be compared with the healthy one, evaluates the relationship between opposing muscles (for example, hamstrings and quadriceps), and detects deficits that are not noticeable during training. It is used following muscle, ligament, and shoulder injuries, and forms part of the assessment of the knee, shoulder, and elbow.

The main risk is a relapse, and with muscle injuries, the second one is usually longer than the first. A muscle that no longer hurts may still retain a strength deficit or fatigue tolerance deficit that only appears under exertion. Measuring this before returning helps to determine whether further work is needed, along with physical examination and how the area responds to training.

Yes, with a referral from your sports doctor or your club's medical team, indicating what they wish to measure. The same battery of tests is used to assess your differences in strength or mobility between one side and the other, which is what is done in pre-season evaluations. These measurements do not predict who is going to get injured, but they do provide your own baseline: if an injury occurs later on, it is compared against your previous condition and not just against general population tables.