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| Sunday Times article 280719 |
Today's Sunday Times article on training for the Straits Times run says avoid muscle cramps by consuming more sodium? Nah, not totally true. Not at all actually. I've written about this exact same topic way back in 2015.
In that post, I wrote about how renown sports scientist Tim Noakes found no significant differences in sodium and magnesium levels in 72 ultra marathoners among those who cramped and those who did not cramp (Schwellnus et al, 2004). They found that sweating too much had no real effect on muscle cramps.
Try to think of when you last had a muscle cramp? After running 30 km in your marathon or after 3 km in a 10 km race?
Muscular fatigue (or when your muscles get too tired) is what really causes muscle cramps. The muscle cramps so you can avoid injury before you can push yourself further. That the Sunday Times article definitely got correct.
Muscle cramping occurs mostly during races than during training. If you started your race too fast or you pushed too hard, that may cause your muscle to fatigue and then cramp. Other studies have shown that tough, hilly courses and poor pacing are predictive of muscle cramps.
I also wrote that sports drinks cannot replace your sodium levels during exercise. Your electrolyte levels actually rise when you sweat a lot. Yes, you read correctly. I'll explain this below.
Assume you have five cups of water and five teaspoons of salt/ electrolytes in your body. Say you sweat 2 cups of water and a teaspoon of salt/ electrolytes when you exercise, the concentration of salt/ electrolytes is now higher. It will remain higher as you become more dehydrated.
Apply this concept to our running physiology. Our sodium (salt) concentration is about 140 mM (or 3.2 grams of salt in every litre of blood). Our sweat has a sodium concentration between 20-50 mM. Even for a "salty sweater" (those who lose more salt than others when they sweat), they lose about 1.1 grams of salt max in every litre of sweat.
Hence, the theory that muscle cramping is caused by low electrolytes/ salt as a result of sweating is not true. You will definitely lose more water than sodium when you sweat. You can read more of that here.
You read it here first. Now you definitely know.
References
Dugas J (2006). Sodium Ingestion And Hyponatraemia: Sports Drinks Do Not Prevent A Fall In Serum Sodium Concentration During Exercise. BJSM> 40:377. DOI: 10.1136/bjsm.2005.022400.
Schwellnus MP, Nichol J, Laubscher T and Noakes T (2004). Serum Electrolyte Concentrations And Hydration Status Are Not Associated With Exercise Associated Muscle Cramping (EAMC) In Distance Runners. BJSM. 38: 488-492. DOI: 10.1136/bjsm.2003.007021.
*The Sunday Times article is on page A27 under the Sports section. Go take a look.
*The Sunday Times article is on page A27 under the Sports section. Go take a look.
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