Why a Paralympic swimmer can be an S8 in freestyle and an SB7 in breaststroke

Watch any Para swimming final and the graphics will tell you it is the men's 100m freestyle S9. Nothing on the broadcast will tell you what S9 means.

It is the most-asked question about Para sport and the least-answered, so here is the system.

Classification is about the sport, not the diagnosis

The point people usually start from — that classes group athletes by medical condition — is wrong, and it is the reason the rest of the system looks arbitrary.

The IPC defines a sport class as a category for competition, defined by each International Federation in its own classification rules. Athletes are grouped by how much their impairment affects performance in that specific sport.

Which is why two athletes with completely different impairments can be in the same class. If the effect on swimming is comparable, the class is the same. And why a class in swimming does not transfer to athletics: the demands are different, so the assessment is different.

The eligible impairments

The IPC's classification page describes the impairment types that can make an athlete eligible:

• Impaired muscle power — reduced or no ability to contract muscles to generate force
• Impaired passive range of movement — reduced ability for a joint to be moved
• Limb deficiency or limb length difference — total or partial absence of a limb, or anatomically irregular limb dimensions
• Short stature — reduced total body length from congenitally or developmentally reduced bone length
• Coordination impairments — spasticity, motor ataxia and dyskinesia, affecting the ability to voluntarily produce a full range of skilled movement
• Vision impairment — reduced or no visual function even with the best possible correction
• Intellectual impairment — restriction in general mental functions

Having one of these is necessary but not sufficient. The impairment must also meet the minimum criteria the sport sets, and affect that sport.

Reading the swimming codes

Para swimming is the clearest illustration, because it uses three prefixes.

S — freestyle, butterfly and backstroke. SB — breaststroke. SM — individual medley, worked out from the S and SB classes using a formula.

The numbers then run in bands:

• S1–S10 / SB1–SB9 — physical impairment, lower numbers meaning greater impact on swimming
• S/SB11–13 — vision impairment, from S11 (most severe) to S13
• S/SB14 — intellectual impairment, covering swimmers affected in pattern recognition, sequencing and memory, or with slower reaction times

Which is why the numbers differ by stroke

The IPC states it directly: because of the different demands of S and SB events, swimmers are often allocated different S and SB sport classes.

Breaststroke is the outlier. It depends on a simultaneous, symmetrical leg kick in a way freestyle and backstroke do not. A swimmer with strong arms and limited leg function loses far more in breaststroke than in freestyle — so the same person can be an S8 and an SB6.

That is the system behaving correctly, not an inconsistency.

Who decides

Classification is done by classifiers — the IPC requires that they hold relevant qualifications and competencies, are knowledgeable in their sport, and are certified as officials by the International Federation.

Athletes are assessed and can be reassessed. Conditions change; some are progressive; some athletes are classified young and grow. A class is a current judgement, not a permanent label.

The part that is genuinely hard

Classification is where most Para sport controversy lives, and it is worth saying why rather than pretending it is settled.

Grouping people by functional impact means drawing lines through a continuum, and any line has someone just either side of it. Assessment involves judgement as well as measurement. Athletes near a boundary can gain or lose a great deal from a decision they do not control.

None of that makes the system unnecessary. Without it there is no competition at all, only the athlete with the least impairment winning everything. But it does explain why classification is argued about at every Games — and why it deserves more airtime than the two seconds a graphic gives it.