Do Athletes Need More Salt?
Athletes spend a portion of their week pushing their bodies to the absolute limits, whether that is training for direct sport involvement or performance training to become better at sport performance. It's the athletes job to push their bodies. Rarely are there sports where an athlete would not benefit from a higher performing body. How fast athletes recover from training is a large predicator on how they will perform their next training session. There are 6 different mechanisms that contribute towards muscle soreness (1). Delayed, onset, muscle soreness (DOMS) is talked about the most often. DOMS is caused by microtrauma to the muscle and the shift of fluid and electrolytes (1) .
Most doctors who study sweat-testing, prefer to have individualized programs for
hydration as each person loses electrolytes and water at a different rate. The simplest testing method though is the is to measure whole-body changes in body mass during exercise (2). After exercise stimulates a change in sweat composition, the level of salt in the sweat increases and the amino acids in the sweat decrease (3). Due to these results, it shows that sodium and chloride reabsorption is influenced by the pairing of potassium and amino acids (3). Fluid loss typically means water and electrolytes. Rehydration also means adequate sodium, other electrolytes, and water. Post exercise athletes are advised to consume more water than that was lost, however plain water alone will prompt diuresis and prevent long term maintenance of water balance (4). Let's reiterate that, water alone post exercise will not allow your body to rebalance it's hydration levels. The amount of sodium per liter of water consumed after exercising influences rehydration due to it's effect on extracellular fluid osmolality.
Football players need more salt than an average office worker, but active people who have performance hobbies may want to monitor and manage their hydration. Mainstream sports drinks may provide more than water, but still fall short in speeding up the rehydration process, despite their convenience.
Athletes concocting their own post workout hydration formulas need to monitor their needs based on their sodium lost. The goal is to replace sodium lost, not necessarily hyper-load on sodium post workout. Athletes should also pay attention to muscle cramps and health problems. Well constructed formulas will address the needs of magnesium, potassium, and calcium for total rehydration.
(1) Lewis PB, Ruby D, Bush-Joseph CA. Muscle soreness and delayed-onset muscle soreness. Clin Sports Med. 2012 Apr;31(2):255-62. doi: 10.1016/j.csm.2011.09.009. Epub 2011 Nov 23. PMID: 22341015.
(2) Baker LB. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Med. 2017 Mar;47(Suppl 1):111-128. doi: 10.1007/s40279-017-0691-5. PMID: 28332116; PMCID: PMC5371639.
(3) Murphy GR, Dunstan RH, Macdonald MM, Borges N, Radford Z, Sparkes DL, Dascombe BJ, Roberts TK. Relationships between electrolyte and amino acid compositions in sweat during exercise suggest a role for amino acids and K+ in reabsorption of Na+ and Cl- from sweat. PLoS One. 2019 Oct 3;14(10):e0223381. doi: 10.1371/journal.pone.0223381. PMID: 31581276; PMCID: PMC6776299.
(4) Evans GH, James LJ, Shirreffs SM, Maughan RJ. Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration. J Appl Physiol (1985). 2017 Apr 1;122(4):945-951. doi: 10.1152/japplphysiol.00745.2016. Epub 2017 Jan 26. PMID: 28126906.