Run Well Juliet McGrattan (microsoft ebook reader TXT) 📖

but don’t forget that you lose fluid through your breathing and panting too.

1 Immediately before you run, weigh yourself naked.

2 Go for a run (dressed!) – a one-hour run is recommended.

3 After your run, strip naked again, towel dry off any sweat and weigh yourself.

4 Subtract your after-run weight from your pre-run weight and convert this to millilitres, e.g. 70kg-69kg = 1kg and 1kg = 1000mls.

5 If you have had a drink during your run, then add it to this total, e.g. 1000mls + 250mls = 1250mls.

6 This total is your fluid loss over the hour of running – 1250mls or 1.25 litres per hour.

You don’t need to arrive home in perfect fluid balance. This will just give you an idea how much you need to replace after you’ve run and help you decide how much to drink while you’re on the move. Remember, it is only a guide and will vary according to how hot or cold the weather is, how intense your session was and other daily variables. If you need to wee or poo then you’ll have to do it before the pre-run weighing or after the post-run weighing, otherwise you’ll be losing body fluids that haven’t been measured.

Q Can running a marathon cause kidney damage?

A Learning about the hard work the kidneys have to do to maintain fluid balance, it may make you wonder whether running marathons, where hydration can be pushed to its limits, could actually harm the kidneys. Previous studies have shown that up to 85 per cent of ultramarathon runners have some degree of temporary kidney damage at the end of a race. But what about marathons? A small study of 22 marathon runners (41 per cent men), in the 2015 Hartford Marathon in the USA, found evidence of kidney damage with 73 per cent of the runners tested immediately after the marathon showing changes that indicated injury to the tubules of the kidney. Further tests taken 24 hours later showed some improvement, but not complete resolution of these changes. A different study of 167 amateur runners, between age 39 and 61, at the Berlin marathon showed that abnormalities in kidney function induced by running all returned to normal within two weeks after a marathon. What we don’t know is what happens beyond that. Could years of repeated acute episodes of stress on the kidneys affect their future function? Or is the opposite true – that these periods of hardship only act to strengthen and maximise the response of the kidney to injury and are in fact protective? We aren’t even sure exactly what it is about marathon running that causes damage to the kidneys. It’s perhaps a lack of blood flow to the kidneys, dehydration, damage from muscle breakdown or a rise in core body temperature – it may well be a combination of all four.

There are blood tests that are used to check for chronic kidney disease (CKD), which is essentially ‘wear and tear’ on the kidneys, and these are frequently carried out on people with medical conditions such as diabetes and high blood pressure. It would be interesting to know if life-long endurance runners have a higher or lower incidence of CKD, but runners are healthier, less likely to have medical conditions or see the doctor for routine tests, so it would be hard to prove. What we can be sure of is that regular exercise helps to lower our risk of high blood pressure and type 2 diabetes, both important causes of kidney disease. We can look after our kidneys by keeping hydrated, respecting hot weather running and training sensibly. So far there isn’t convincing evidence that running marathons damages your kidneys in the long term.

Did you know?

Each kidney measures 10 to 15 centimetres long and weighs around 160 grams which is equivalent to the weight of three tennis balls.

Q Is it safe to use anti-inflammatories when you run? I’ve heard it can damage the kidneys.

A Non-Steroidal Anti-Inflammatories (NSAIDs) are a family of drugs which include ibuprofen, diclofenac and naproxen. Ibuprofen can be bought over the counter in the UK and is widely used by runners, because it gives effective relief for musculoskeletal pain. It’s not uncommon for runners to take ibuprofen before a long run in anticipation of pain, particularly when they want to perform well in a race or when they are running with an injury. We know that long-term use of NSAIDs can cause health problems, including kidney damage, high blood pressure, heart attacks and gastrointestinal ulcers, but will a single dose before an endurance run pose any risk? Anecdotally up to 75 per cent of ultramarathon runners take ibuprofen before racing so this population is ideal for identifying any potential harm to kidneys. A study published in 2017 gave either ibuprofen or a placebo to 89 runners, to take every four hours during their 50-mile run. Kidney function was tested immediately on finishing the race and 39 of the 89 runners had signs of acute kidney injury at the end of their race. The risk was 18 per cent higher in those that took ibuprofen. For every five runners who took ibuprofen there was one extra case of kidney damage. From this we can conclude that taking ibuprofen during an endurance race increased the risk of kidney damage in this population.

NSAIDs reduce the amount of blood flow in the kidneys and inhibit the formation of prostaglandins, which usually cause dilation of the blood vessels and increased filtration rates in the kidney. If we add the negative effect of dehydration too then we can begin to see why taking ibuprofen during endurance runs is not a risk-free option.

Q The nurse said there was blood in my urine when he did a dip test during a health check. Could this be related to running?

A A dip stick urine test will detect blood in the urine that is not visible to the naked eye. We call this microscopic haematuria (blood which