What is rhabdomyolysis?
Rhabdomyolysis, or rhabdo, is what happens when skeletal muscle fibres break down and dump their internal contents into the bloodstream. A muscle cell holds a lot of myoglobin, the protein that stores oxygen inside the fibre, along with creatine kinase, potassium and phosphate. Rupture enough cells at once and all of that arrives in the blood faster than the body can safely process it.
Myoglobin is the part that does the damage. A small amount passes through the kidneys and out again without any trouble, but a large amount crystallises in the kidney tubules, blocking them physically and attacking them chemically at the same time. That is acute kidney injury, and at the severe end it is complete renal failure and dialysis.
How it happens in rugby
It happens when a session demands more of the muscle than the muscle can structurally take. In rugby that mismatch turns up in a few familiar places:
- Coming back for pre-season is the obvious one, because players who have done very little all off-season walk into a full conditioning session with muscle that has less of the structural tolerance it finished last season with, and the first week back is where this tends to happen
- Punishment sessions do it too, the character-building ones with endless running, hundreds of bodyweight reps and repeat sprints to exhaustion, where the point of the session is suffering rather than adaptation and the muscle keeps being asked to work long after it has stopped coping
- A pile of eccentric work in players who have not built up to it is the third route in, because lengthening a muscle under tension damages it more than shortening it does, and Nordics, walking lunges and box jumps in volume will chew through legs that have not seen them for months
- Heat makes all of that worse, so the same session run in 30°C is not the session that was run in 15°C, and anyone who has not trained in that heat yet should be doing a shortened version of it
How to tell it apart from ordinary soreness
Delayed soreness and rhabdo sit on the same spectrum, and what separates them is how far along it has gone. DOMS hurts and then passes, whereas rhabdo is the end of that line where enough muscle has broken down to threaten the kidneys:
| Feature | Normal DOMS | Rhabdomyolysis |
|---|---|---|
| Pain level | Moderate soreness, muscles ache but still work | Severe pain, muscles feel wooden and immovable and are extremely tender to touch |
| Swelling | Minimal or none | Visible swelling of the muscles that were worked, and they often feel tight and pumped |
| Urine colour | Normal (pale yellow) | Dark brown, tea or cola-coloured, which is the sign that matters most |
| Movement ability | Stiff but can move through full range with effort | Severe difficulty moving the affected limbs. Walking may be extremely painful |
| General symptoms | Localised to the worked muscles | Nausea, vomiting, confusion, fever, malaise, so the player is systemically ill |
| Duration | Peaks at 24-72 hours and resolves within 5-7 days | Persists beyond 5-7 days and may worsen. Does not follow the normal DOMS resolution pattern |
Who is most at risk?
- Anyone coming back from a long break, whether that is the off-season, an injury or a suspension, and the longer they have been out the more careful the first hard session needs to be
- Training in heat nobody has adapted to yet, because the body then has to shed heat and hold its fluid balance at the same time as it deals with the damage from the session
- Players with sickle cell trait need their own plan, because red cells can sickle during hard exercise and choke off blood flow to the working muscle, and muscle starved of blood breaks down. If a player knows they carry the trait, get a doctor involved and build a modified conditioning programme around it rather than running them through the standard one
- Ibuprofen and the other anti-inflammatories are a bad idea around hard training, because they cut blood flow to the kidneys at the moment the kidneys may be dealing with myoglobin
- Turning up dehydrated concentrates myoglobin in the kidneys and makes tubular damage more likely, and pre-season usually runs through the hottest weeks of the year, so this one stacks with the heat
- Some supplements and medicines add to it, including creatine at excessive doses, stimulant pre-workouts, statins and a few psychiatric drugs, so ask players what they are taking before pre-season starts rather than after something has gone wrong
Preventing it is a coaching job
It comes out of a gap between what the session demands and what the players in front of you are ready for, and closing that gap sits with the coach rather than the player:
- Start pre-season somewhere around 40 to 50% of the intensity of a mid-season session, then add no more than 10 to 15% of volume or intensity a week, and give it three or four weeks before you ask legs for heavy eccentric loading
- Take the punishment sessions off the plan altogether, the running until someone is sick, the military drills, the session whose stated point is that it hurts, because none of it buys an adaptation and all of it builds the conditions for rhabdo. The coach who programmes them is confusing suffering with conditioning
- Two players on the same pitch should not always be doing the same session, so somebody six weeks off with an injury gets less than the player who trained all summer, and you set each load off what that player has actually been doing lately
- Weigh players in and out of pre-season sessions, treat more than 2% of body weight lost across a session as a sign they did not drink enough, and put a hydration break in every 15 to 20 minutes when it is hot
- Every player should know before pre-season starts that dark urine after training is not normal and not something to sleep on, and that they ring someone about it the same day
- Bring the eccentric work in slowly, so that Nordics, Romanian deadlifts, walking lunges and plyometrics all arrive in small doses first. Four sets of twelve Nordics in week one is a programme nobody has built up to yet