Essential minerals after exercise

First of all, let’s be clear on what we mean when we say ‘mineral’.  A mineral is a naturally occurring substance that is inorganic and is representable by a chemical formula.  Dietary minerals are required by living organisms.  There are a number of vital minerals that we need to regularly consume in fairly large quantities in order to survive.  These include sodium, potassium, phosphorous, magnesium.  We also require trace minerals.  These are smaller amounts of minerals that are nonetheless vital to our optimal functioning.  These include iron, manganese, zinc, selenium and iodine.

One of the minerals required in the greatest amount is sodium, generally consumed in the form of  sodium chloride, or common salt.  Many foods do contain salt, and for normal day-to-day functioning this is usually enough.  Sodium is needed all around your body.  Alongside potassium it helps maintain the right blood volume and pressure by ensuring the required amount or water is drawn out of the blood stream as it flows through the kidneys.  Again, alongside potassium, it is required for normal nerve and muscle function.  The electrical impulses that travel via your nerves and excite your muscles are carried by changing levels of sodium and potassium.

As soon as you exercise, you will sweat. Your sweat contains water along with some minerals, importantly chlorine, potassium and sodium.  With intense exercise a surprisingly large amount of sweat is produced, and you can be left in a severe state of dehydration.  In several studies  over recent years Shirreffs had described the need to replace not only water, but salt when trying to return your body to a state of euhydration – a good ‘normal’ level of hydration.  Only with actively replacing the salt you excrete can you quickly bring your body back to its normal state.  If the exercise has been very intense this is particularly important, as it can take several days for your body to recover just through eating and drinking normally.  Just drinking water to rehydrate without also ingesting the appropriate amount of salt can, in extreme cases, lead to muscle cramps, nausea, and even seizure, requiring hospitalisation to treat (Reynolds, 2012).

It’s not just salt replacement that becomes important after exercise.  Lots of other minerals are used up when we exercise, so it’s advantageous to try and replace all of them if possible, especially if we aim to exercise again soon.  Snell (2010) found this with a study comparing different rehydration drinks.  One was lemon-flavoured water (Crystal Light). One contained water, sugars, sodium and potassium (Gatorade).  The third contained these ingredients as well as calcium, magnesium, amino acids, thiols and vitamins (Rehydrate).  Participants performed rounds of exercise to exhaustion.  After a bout of exercise, rehydrating with Crystal Light did not create a state of euhydration and subjects experienced a 6.5% decrease in performance whilst exercising again afterwards.  Drinking Gatorade helped more, with individuals experiencing only a 2.1% drop in performance.  Rehydrate was the only drink that returned participants to a state of euhydration.  These people also performed better in a subsequent bout of exercise, showing a 7.3% increase in treadmill time relative to that of the dehydrated state.  This study shows clearly that many minerals are vital for us to recover from exercise.

The benefits of increased calcium levels were shown by Gaffney-Stomberg in 2014.  Over 9 weeks 243 recruits undergoing military training took a daily dose of 2000mg of calcium, combined with 1000IU of Vitamin D.  Measures of bone density were taken, as well as a measure of bone thickness.  Both the male and female recruits showed better levels of calcium in their blood at the end of the trial, as well as denser and thicker bones.  There were also less incidences of stress fractures than had been predicted, suggesting calcium supplementation provided a protective effect against bone damage.  This study shows that when we work our bodies harder, we need to remember that not only are our muscles working hard, but our skeleton is too, and it needs extra care and fuel just like all of our soft tissues.

It is clear that if we want to get all the benefits we can out of our exercise regime we must make sure we are helping our bodies cope with the strain of exertion.  This means we need to recognise the strain which exercise puts on our bodies, and make sure we consume more minerals to combat this.

References:

1.Li X. et al.  Effects of a multivitamin/multimineral supplement on young males with physical overtraining: a placebo-controlled, randomized, double-blinded cross-over trial. Biomed Environ Sci. 2013 Jul;26(7):599-604.

2. Maughan RJ, Leiper JB, Shirreffs SM. Factors influencing the restoration of fluid and electrolyte balance after exercise in the heat. Br J Sports Med. 1997 Sep;31(3):175-82.

3. Maughan RJ, Leiper JB, Shirreffs SM. Restoration of fluid balance after exercise-induced dehydration: effects of food and fluid intake. Eur J Appl Physiol Occup Physiol. 1996;73(3-4):317-25.

4. Maughan RJ, Shirreffs SM. Recovery from prolonged exercise: restoration of water and electrolyte balance.J Sports Sci. 1997 Jun;15(3):297-303.

5. Shirreffs SM, Maughan RJ. Volume repletion after exercise-induced volume depletion in humans: replacement of water and sodium losses. Am J Physiol. 1998 May;274(5 Pt 2):F868-75.

6. Shirreffs SM, Sawka MN. Fluid and electrolyte needs for training, competition, and recovery. J Sports Sci. 2011;29 Suppl 1:S39-46.

7. Snell PG. et al. Comparative effects of selected non-caffeinated rehydration sports drinks on short-term performance following moderate dehydration. J Int Soc Sports Nutr. 2010 Aug 22;7:28.

8. Reynolds CJ et al.  Exercise associated hyponatraemia leading to tonic-clonic seizure. BMJ Case Rep. 2012 Aug 27;2012.