November 2022

What Causes Muscle Cramps in Marathoners?

 The runner’s bane is muscle cramps, those painful, activity-stopping pains in side of the ribcage that come from nowhere. Even 70 years after the jogging craze hit, we’re still not sure why these happen. Years ago, one study tested the idea that it was fluid in the stomach itself that was tugging on the omentum, the suspension system for the organs. Other studies have determined that they’re not due to dehydration or electrolyte imbalance. More recently, the “altered neuromuscular control theory” (ANCT) hypothesized that “excessive demand according to their current state of training [generates] an alteration in neuromuscular control.” 

A study from Spain tested the hypothesis that cramps are from dehydration and electrolyte depletion combined vs muscle damage. They looked at 64 runners who finished a marathon without cramping and compared them to the 20 finishers who did. They hypothesized that crampers had greater concentrations of muscle damage markers but no differences in dehydration or electrolyte losses.

Since they had data on their cardiovascular capacities, they could estimate the intensities at which each one ran to see if that might impact cramping likelihood. 

They found that crampers did not lose more body weight and were no more dehydrated or in electrolyte imbalance. They did, however, have higher markers of muscle damage immediately and 24 hours after the race, leading to the conclusion that crampers “subjected their muscles to an excessive intensity demand in relation to their fitness level,” supporting the ANCT. This suggested that one’s training was linked to the risk of developing cramps during the race. The authors also suggested that strength training would likely help runners,  especially those prone to cramping.                          

JSCR June 2022

Resistance Training Boosts Longevity, Too

Most health and wellness studies and experts tout the benefits of aerobic, or cardiovascular, exercise for reducing morbidities such as heart disease, metabolic disorders, and many cancers. These benefits are a result of making the heart pump large volumes of blood through the vascular system, taking oxygen from the lungs to the large muscles in rhythmic and long-duration movements such as walking, jogging, cycling and swimming. But resistance, or strength, training (RT) offers very similar benefits for older adults even though it does not do what cardio exercise does, as we’ve discussed here, here, and here. 

A study from the British Journal of Sports Medicine (Sept. 2022) found that regular RT, in fact, does reduce “all-cause and cardiovascular mortality, with the strongest effects observed when the two types of exercise are combined.” Nonetheless, RT alone is pretty potent: while those who did both types of exercise had around a 40% lower risk of death during the 9-year study compared to those who did neither, those who only lifted had a 9% lower risk.

The combo training benefited women more than it did men, maybe because males tend to have more physically demanding jobs or chores. 

The authors hypothesize that RT favorably affects body composition. During RT, muscles have to “redirect more blood flow..the heart is pumping harder, the lungs breathe more” etc. The social aspect, of training in a gym environment, might also help older adults in ways that the physical activity doesn’t account for.        

Medscape Oct. 2022

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