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Fighting Muscle Cramps With Two Spices and One Hot Fruit

Eichner, E. Randy MD, FACSM

doi: 10.1249/JSR.0000000000000298
Pearls and Pitfalls
Free

Address for correspondence: E. Randy Eichner, MD, FACSM, 321 Baudin Way, Sonoma, CA 95476; E-mail: reichner1@comcast.net.

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Introduction

As athletes compete and cramp in the heat, sellers of “cramp busters” compete to corner the market. This year, the momentum may be with Flex Pharma, Inc., where marketing is in the saddle and riding science, to promote “Hotshot” for exercise-associated muscle cramping (EAMC). According to the investment banking firm Jefferies, an advisor to Flex Pharma, the marketing plan resembles what made Svedka vodka a “cult brand.”

The aim is to make Hotshot a cult brand among “alpha humans for whom EAMC can mean a humiliating loss of power, achievement and control.” The plan creates “whitespace” by claiming that existing products do not work for EAMC. It then tells an “inspiring origin story” and offers a “genius solution,” Hotshot, from a Nobel-Prize winning “endurance athlete.” And it seeks an “evangelizing subculture” of endurance athletes, especially cyclists and triathletes (11). Hotshot is two spices, ginger and cinnamon, and capsaicin, an extract from chili pepper, which is one hot fruit (some say vegetable). Now the Flex Pharma marketing juggernaut is touting Hotshot for heat cramping in football. This is a bridge too far. Let me explain.

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The Hype

Flex Pharma launched Hotshot on June 2, 2016, the same day it sponsored a symposium on EAMC at the American College of Sports Medicine’s (ACSM) Annual Meeting. The 84 slides from that symposium are on the Internet (10). The science is weak but the infomercial is strong. They tell their origin story, about two brilliant neuroscientists who suffered from debilitating arm cramping while sea kayaking and “set out to find a solution.” One likely solution would have been to strengthen their arms, but this is not my focus.

To create whitespace for Hotshot, the trend of the ACSM symposium is to dismiss dehydration and/or salt depletion in EAMC and to tout the “altered neuromuscular control” (or the “it is the nerve”) hypothesis of Schwellnus and Miller (9,12). By this hypothesis, in plain words, Hotshot’s “hot-spicy kick” shocks the mouth and sparks an oropharyngeal neural reflex that tells the brain to tell the spinal cord to tell the hyperactive alpha motor neurons to calm down and let the cramping muscles relax.

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The Science

Flex Pharma science on Hotshot for EAMC comes from uncontrolled observations on endurance athletes in the field and from two laboratory models of cramping that seem irrelevant to heat cramping in summer football or tennis. In the field study, 31 endurance athletes logged their EAMC for 2 wk and then tried Hotshot for 2 wk. Sure enough, as expected from the placebo effect, some of them thought Hotshot helped. This is anecdote, not science.

One laboratory model involves hitting the tibial nerve percutaneously with low-frequency trains of electrical stimuli until the flexor hallucis brevis muscle cramps. In other words, the big toe is shocked until it cramps. Setting aside problems of interpretation, practice effect, and placebo response, in this model, pickle juice works fast (in about 85 s) to alleviate the cramp, presumably by the same oral neural reflex that Hotshot evokes, because Hotshot has similar effects in this model. Neither salty sweating nor dehydration affects cramp susceptibility in this big-toe model of Miller (9). The science may be solid, but does this unique model apply to heat cramping in football? Not really.

The other laboratory model involves plantar flexing the foot to pre-shorten the gastrocnemius, isolating the triceps surae, and performing maximal voluntary contraction for 90 s or until cramping. In other words, it involves self-induced calf cramping. When 20 volunteers with a history of EAMC did this, Hotshot (vs vehicle control) mitigated the cramping. But this “benefit” was minor or negligible in all but four or five of the 20 subjects (see slide 79 of 84), and subjects could distinguish the “hot-spicy kick” of Hotshot from the strong citrus taste of vehicle control, suggesting a placebo response. This science is unconvincing (3).

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Not So New

Hotshot comprises ginger, cinnamon, and capsaicin. Not so new. More than 50 home remedies for muscle cramping are discussed on the Internet. Ginger goes back at least 10 yr. Cinnamon has been used for centuries for menstrual cramping. Cayenne peppers (contain capsaicin) were advised for cramping nearly a decade ago. A competitor of Hotshot, Apple Cider Vinegar (ACV) Cramp Cure, hit the market almost a year before Hotshot, but lacks the marketing juggernaut of Hotshot. ACV, like Hotshot, is capsaicin-based, but has vinegar, not ginger and cinnamon. ACV, like Hotshot, offers testimonials from athletes who swear by it.

But the most glowing testimonials on the Internet come from athletes who use Cramp Stop (from New Zealand) for EAMC. “Cramp Stop is a miracle! At the first twinge of EAMC, you spray it into your mouth. Within seconds, your cramps are gone!” Cramp Stop has been on the market for 20 yr. It is homeopathic, so in essence, Cramp Stop has nothing in it. It is all placebo power. Who can blame Hotshot if they are jealous?

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Heat Cramping

The Flex Pharma ACSM symposium gives short shrift to any role for fluid or salt depletion in EAMC. It follows Schwellnus and Miller to say “cramping is not caused by dehydration or electrolyte imbalance” (see slide 53 of 84). It covers only one study to support this (14). Two studies by the same researchers find lower serum sodium levels postrace in ultramarathoners and triathletes who cramp versus those who do not (13,16). This suggests the possibility of salt depletion in at least some cramping endurance athletes (5). A study of heat exhaustion in underground miners finds that those who cramp are more dehydrated and likely more sodium-depleted than those who do not cramp, and a study of marathoners finds that the saltiest sweaters have the lowest post-race serum sodium levels (4,8). But let it be. Maybe in some or many endurance athletes who cramp, the cause is not at all related to dehydration or salt depletion, but only to alpha motor neuron hyperactivity secondary to muscle fatigue or damage. So if “alpha human” endurance athletes want to try Hotshot for EAMC, fine. My focus is on summer football.

The Hotshot symposium ignores the strong case for salty sweating as integral to EAMC when football players go hard in the heat. Learning from cramping in miners and stokers, Harvard researchers studied heat cramping in men building the Hoover Dam and in steelworkers. They tied it to loss of salt in sweat, reversed it with intravenous saline, and concluded that sodium chloride is useful to prevent heat cramps (17). In our study of college football players, those prone to EAMC (vs those not) were heavier and saltier sweaters (15). Godek et al. (7) also found large sweat salt losses in some professional football players. Bergeron (1) studied heat cramping in tennis players, tied it to heavy, salty sweating, and concluded that appropriate salt and fluid intake can avert it. Many team physicians have found “saline solutions” for disabling heat cramping in athletes.

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Conclusion

In cramping, Hotshot is not so new. In football, it is not so smart. In tennis, Bergeron (2) prevents heat cramping by adding salt to the diet and to sports drinks on-court at the first twinge of EAMC. We and many others find the same works in football (6). Hotshot for heat cramping in football is bad advice. It does not treat root causes. It delays proper therapy. It is like disabling your blaring smoke alarm and going back to bed. For heat cramping in sports, seek salty solutions.

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References

1. Bergeron MF. Heat cramps. Fluid and electrolyte challenges during tennis in the heat. J. Sci. Med. Sport. 2003; 6:19–27.
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15. Stofan JR, Zachwieja JJ, Horswill CA, et al. Sweat and sodium losses in NCAA football players: a precursor to heat cramps? Int. J. Sport Nutr. Exerc. Metab. 2005; 15:641–52.
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Copyright © 2016 by the American College of Sports Medicine.