Bananas May Be Cramping Your Style

banana Dr. Aaron Case (Feb 2011)

Nearly everyone has heard at some point that the best way to prevent running cramps is to drink enough water (+/-salt), eat bananas, and don’t get too hot.  Although this is generally great advice for other health reasons, this advice is based upon the extremely persistent myth that cramps are caused by dehydration, heat and/or electrolyte imbalances.  

 

Definition: Exercise associated muscle cramping (EAMC) is typically experienced as a painful isolated spasm of a muscle that may cause a brief “buckling” in your stride (or side) or the cramp may persist for several seconds until the muscle involved is stretched out and/or relaxes on its own.  (NOTE: It is well established that some athletes suffer cramps due to an underlying medical condition; therefore it is important to remember that not all cramps are EAMC. The medical causes of cramping will not be discussed here.) 

Furthermore, another key issue regarding electrolytes is getting enough salt to replace sweat losses.  Not enough salt (sodium) in the body, known as hyponatraemia, can have detrimental effects on performance and in worst case scenarios, deadly consequences.  This is why endurance sports drinks or gels with sodium are better than water and sugar alone especially when sweat rates are high and/or prolonged.  Hyponatraemia, however, does not resemble the localized muscle cramping of EAMC.

So, if heat, dehydration and electrolyte imbalances are not to blame for EAMC, then what is? Research suggests the following explanation of EAMC:
  • Research has shown that blood electrolyte (sodium, potassium, etc.) concentrations are normal in those who experience acute EAMC, compared to non-cramping athletes.
  • There are four prospective studies, involving athletes from marathon running and triathlonsthat showed no relationship between electrolyte abnormalities and EAMC.  
  • These four research studies also showed no difference in hydration levels. No other published studies have shown that EAMC subjects are less dehydrated in comparison with  ”non-crampers”. 
  • Furthermore, EAMC is known to occur in individuals exercising in moderate to cool temperatures including swimmers (1).

runner with crampIs Muscle Fatigue the culprit?

In a study of over 1800 marathon runners, 26% of who reported a history of EAMC, indicated that perceivable muscular fatigue consistently occurred prior to EAMC (2).

Observational studies indicate that athletes who suffer EAMC frequently report:

  • Poor event-specific conditioning
  • Exercising/competing at a higher intensity than one’s training
  • EAMC onset in the late stages of events 
  • An additional study indicated that higher exercise intensity (faster race time) was associated with EAMC in a group of triathletes.

PREVENTION OF EAMC

Both clinical studies and practical experience agree that the best way to prevent EAMC is to delay the onset of the acute muscle fatigue that triggers cramping. This includes:

  • Incorporating exercises functional to running, such as calf raises/drops and hill running to help prevent calf/foot cramps, heel walking for shin muscle cramping, drop squats or step-ups for quad/thigh cramping, and glute bridges and/or ball hamstring curls for hamstring cramping.

calf raises

  • Your long run should be less than 50% of your total weekly mileage.  For example, if your long run is 20 km, you should have run at least a total of 20 km during the week to help prevent muscle cramping and injuries in general.  That might be three other runs of 6-7 km each or two runs of 10 km each.  Elite runners ensure their long run is closer to 25-30% of their total weekly running distance.
  • Being well-rested (enough sleep) prior to longer/harder runs
  • Being well-fuelled prior to your run (eat a small meal within 2-3 hours typically) as well as during runs > 1 hour to prevent low glycogen stores associated with muscle fatigue.
  • Very gradually introducing speed work, hills and long runs

 

Summary and Conclusion 

Though good hydration and a diet including electrolytes will have many benefits to your health, your tendency to muscle cramping will likely remain unaffected by these strategies.  It seems to be adequate training to prevent muscle fatigue is a better solution.  The problem with association is that when we are fatigued we are often also hot, thirsty and perhaps even craving salty foods and therefore may be linking the wrong causes to EAMC.

 Therefore, when training up to the marathon level, unless dietary deficiencies exists, the only electrolyte lost in any appreciable amount should be salt/sodium, and all other electrolytes or other minerals and vitamins should be unnecessary.  As far as other nutrients in runs over 1 hour, carbohydrates (gels, sports drinks, etc.) can be very helpful to maintain speed and endurance and to prevent muscle (by preventing muscle fatigue related to low glycogen stores). 

Personally, I still enjoy a banana about 15-30 minutes prior to my runs for energy and general nutritional value.  However, if I ever get a cramp, instead of consuming water and/or salt excessively, I first stretch out the area, and if possible, continue running with decreased intensity.  In the future, I then try to incorporate more of the preventative measures listed above into my training.

Further research is required to fully clarify the exact cause of EAMC, and hopefully this will guide appropriate preventive strategies in the meantime.

References
  1. Laird RH. Medical care at ultraendurance triathalons. Med Sci Sports Exerc 1989; 21: S222-225.
  2. Manjra SI, Schwellnus NP, Noakes TD. Risk factors for exercise associated muscle cramping (EAMC) in marathon runners. Med Sci Sports Exerc 1996; 28(5 suppl): S167.