Reflex Inhibition of Electrically Induced Muscle Cramps in Hypohydrated Humans

Practical Nutrition Strategies to Support Basketball Performance during International Short-Term Tournaments: A Narrative Review

A short-term (e.g., 6 days) basketball tournament is a shorter version of international tournaments, and qualification in it enables participation in international tournaments such as the Olympics and World championships or preparation before major tournaments. Time for recovery between matches is shorter compared with major tournaments, resulting in an accentuated load on players, which can be repeated up to four times within the 6-day competition period. Therefore, nutritional strategies need to focus on faster and adequate recovery after each match as well as optimum fuelling and hydration before and during matches. Travelling can also create additional challenges when preparing and/or applying those nutritional strategies. There are some particular evidence-based sport foods and ergogenic aids that can improve intermittent activity and/or the execution of motor skills, which may facilitate basketball players' recovery and performance. The present review provides practical nutritional strategies to support short-term basketball tournaments based on players' physiological needs and current sport nutrition guidelines.

Pickle Juice Intervention for Cirrhotic Cramps Reduction: The PICCLES Randomized Controlled Trial

INTRODUCTION

Muscle cramps are common among persons with cirrhosis and associated with poor health-related quality of life. Treatment options are limited. We sought to determine whether pickle juice can improve muscle cramp severity.

METHODS

We enrolled 82 patients with cirrhosis and a history of >4 muscle cramps in the previous month from December 2020 to December 2021. Patients were randomized 1:1 to sips of pickle juice vs tap water at cramp onset. Our primary outcome assessed at 28 days was the change in cramp severity measured by the visual analog scale for cramps (VAS-cramps, scaled 0-10). Cramps were assessed 10 times over 28 days using interactive text messages. Secondary outcomes included the proportion of days with VAS-cramps <5, change in sleep quality, and global health-related quality of life measured using the EQ-5D.

RESULTS

Overall, 74 patients completed the trial, aged 56.6 ± 11.5 years, 54% male, 41% with ascites, 38% with encephalopathy, and model for end-stage liver disease-sodium score 11.2 ± 4.9. Many patients were receiving other cramp therapies at baseline. The baseline VAS for cramps was 4.2 ± 3.4, the EQ-5D was 0.80 ± 0.10, and 43% rated sleep as poor. At trial completion, the respective values for the pickle juice and control arms were -2.25 ± 3.61 points on the VAS for cramps, compared with control tap water (-0.36 ± 2.87), P = 0.03; a proportion of cramp-days with VAS-cramps <5 were 46% vs 35% (P = 0.2); and the change in sleep quality was not different (P = 0.1). The end-of-trial EQ-5D was 0.78 ± 0.10 vs 0.80 ± 0.10 (P = 0.3). No differences in weight change were observed for those with and without ascites.

DISCUSSION

In a randomized trial, sips of pickle brine consumed at cramp onset improve cramp severity without adverse events.

An Evidence-Based Review of the Pathophysiology, Treatment, and Prevention of Exercise-Associated Muscle Cramps

Exercise-associated muscle cramps (EAMCs) are common and frustrating for athletes and the physically active. We critically appraised the EAMC literature to provide evidence-based treatment and prevention recommendations. Although the pathophysiology of EAMCs appears controversial, recent evidence suggests that EAMCs are due to a confluence of unique intrinsic and extrinsic factors rather than a singular cause. The treatment of acute EAMCs continues to include self-applied or clinician-guided gentle static stretching until symptoms abate. Once the painful EAMCs are alleviated, the clinician can continue treatment on the sidelines by focusing on patient-specific risk factors that may have contributed to the onset of EAMCs. For EAMC prevention, clinicians should obtain a thorough medical history and then identify any unique risk factors. Individualizing EAMC prevention strategies will likely be more effective than generalized advice (eg, drink more fluids).

Nutritional approaches to counter performance constraints in high-level sports competition

New Findings

What is the topic of this review?

The nutritional strategies that athletes use during competition events to optimize performance and the reasons they use them.

What advances does it highlight?

A range of nutritional strategies can be used by competitive athletes, alone or in combination, to address various event‐specific factors that constrain event performance. Evidence for such practices is constantly evolving but must be combined with understanding of the complexities of real‐life sport for optimal implementation.

Abstract

High‐performance athletes share a common goal despite the unique nature of their sport: to pace or manage their performance to achieve the highest sustainable outputs over the duration of the event. Periodic or sustained decline in the optimal performance of event tasks, involves an interplay between central and peripheral phenomena that can often be reduced or delayed in onset by nutritional strategies. Contemporary nutrition practices undertaken before, during or between events include strategies to ensure the availability of limited muscle fuel stores. This includes creatine supplementation to increase muscle phosphocreatine content and consideration of the type, amount and timing of dietary carbohydrate intake to optimize muscle and liver glycogen stores or to provide additional exogenous substrate. Although there is interest in ketogenic low‐carbohydrate high‐fat diets and exogenous ketone supplements to provide alternative fuels to spare muscle carbohydrate use, present evidence suggests a limited utility of these strategies. Mouth sensing of a range of food tastants (e.g., carbohydrate, quinine, menthol, caffeine, fluid, acetic acid) may provide a central nervous system derived boost to sports performance. Finally, despite decades of research on hypohydration and exercise capacity, there is still contention around their effect on sports performance and the best guidance around hydration for sporting events. A unifying model proposes that some scenarios require personalized fluid plans while others might be managed by an ad hoc approach (ad libitum or thirst‐driven drinking) to fluid intake.

Portuguese Football Federation consensus statement 2020: nutrition and performance in football

Nutrition is an undeniable part of promoting health and performance among football (soccer) players. Nevertheless, nutritional strategies adopted in elite football can vary significantly depending on culture, habit and practical constraints and might not always be supported by scientific evidence. Therefore, a group of 28 Portuguese experts on sports nutrition, sports science and sports medicine sought to discuss current practices in the elite football landscape and review the existing evidence on nutritional strategies to be applied when supporting football players. Starting from understanding football's physical and physiological demands, five different moments were identified: preparing to play, match-day, recovery after matches, between matches and during injury or rehabilitation periods. When applicable, specificities of nutritional support to young athletes and female players were also addressed. The result is a set of practical recommendations that gathered consensus among involved experts, highlighting carbohydrates periodisation, hydration and conscious use of dietary supplements.

Total Body and Extracellular Water Measures Are Unrelated to Cramp Sensitivity in Euhydrated Cramp-Prone Individuals

Earp, JE, Stearns, RL, Agostinucci, J, Lepley, AS, and Ward-Ritacco, CL. Total body and extracellular water measures are unrelated to cramp sensitivity in euhydrated cramp-prone individuals. J Strength Cond Res XX(X): 000-000, 2020-Spectral bioelectrical impedance analysis (BIA) is a valid and noninvasive tool for measuring total body water (TBW), intracellular water (ICW), and extracellular water (ECW). As altered hydration and electrolyte imbalance have been proposed as one of 2 etiologies for exercise-associated muscle cramps (EAMC), the purpose of this study was to determine if distribution of body water is related to cramp sensitivity in similarly hydrated cramp-prone individuals. To this end, 11 euhydrated subjects who regularly experience EAMC had their relative TBW, ICW, and ECW assessed using 8-pole spectral BIA. Subjects' cramp sensitivity was then assessed by electrically stimulating the tibial nerve at increasing frequencies until a muscle cramp occurred, allowing for the determination of the threshold frequency (TF) at which the cramp occurred. It was observed that TF was not significantly related to TBW (r = 0.087, p = 0.368), ICW (r = 0.105, p = 0.338), ECW (r = 0.087, p = 0.368), or ECW:TBW (r = 0.147, p = 0.280). As cramp etiology is poorly understood, these results add to a growing body of literature questioning the role of hydration and electrolyte imbalance in EAMC. Although fluid distribution may be unrelated to TF in those who commonly experience EAMC, additional research is needed to compare those who commonly experience cramps (athletes as well as individuals with specific neuropathies or pharmacologically induced cramps) with those who do not experience cramps and to determine if acute shifts in body water compartmentalization are related to changes in cramp sensitivity.

Quantitative Analysis of the Acetic Acid Content in Substances Used by Athletes for the Possible Prevention and Alleviation of Exercise-Associated Muscle Cramps

Marosek, SEH, Antharam, V, and Dowlatshahi, K. Quantitative analysis of the acetic acid content in substances used by athletes for the possible prevention and alleviation of exercise-associated muscle cramps. J Strength Cond Res 34(6): 1539-1546, 2020-Athletes regularly consume commercially available food and sports shot products, carbohydrate beverages, and water to improve their physical exertion and to possibly prevent or relieve exercise-associated muscle cramps (EAMCs)-often experienced during practice, training, or competition. Acetic acid, a component of interest within these products, has been recognized for its potential role in cramp reduction. Acetic acid is postulated to mitigate cramping by decreasing alpha motor neuron activity through oropharyngeal stimulation and inhibitory neurotransmitter production, while aiding in the role acetylcholine plays in muscle contraction and relaxation. The purpose of this research is to analytically assess the most viable sources of acetic acid from substances that athletes ingest before or when experiencing these cramps. The range of samples investigated were based on their widespread use in the athletic world: dill and sweet pickle juices, yellow mustard, sweet relish, apple cider vinegar, Hot Shot, PJ Shot, PJ Sport, E-Lyte Sport, Powerade, Gatorade, Smartwater, and Propel (with electrolytes). As hypothesized, pH and enzymatic assay or spectroscopic analyses revealed that yellow mustard, sweet relish, all pickle juices, and the pickle juice products were composed of moderate amounts of acetic acid. Based on established studies resulting in EAMC relief, acetic acid consumption, and the appropriate serving size, the yellow mustard, PJ Shot, and all pickle juices would be the most practical and palatable sources of acetic acid for strength and conditioning professionals to recommend that athletes consume for the possible prevention or alleviation of muscle cramps.

Muscle Cramping During Exercise: Causes, Solutions, and Questions Remaining

Muscle cramp is a temporary but intense and painful involuntary contraction of skeletal muscle that can occur in many different situations. The causes of, and cures for, the cramps that occur during or soon after exercise remain uncertain, although there is evidence that some cases may be associated with disturbances of water and salt balance, while others appear to involve sustained abnormal spinal reflex activity secondary to fatigue of the affected muscles. Evidence in favour of a role for dyshydration comes largely from medical records obtained in large industrial settings, although it is supported by one large-scale intervention trial and by field trials involving small numbers of athletes. Cramp is notoriously unpredictable, making laboratory studies difficult, but experimental models involving electrical stimulation or intense voluntary contractions of small muscles held in a shortened position can induce cramp in many, although not all, individuals. These studies show that dehydration has no effect on the stimulation frequency required to initiate cramping and confirm a role for spinal pathways, but their relevance to the spontaneous cramps that occur during exercise is questionable. There is a long history of folk remedies for treatment or prevention of cramps; some may reduce the likelihood of some forms of cramping and reduce its intensity and duration, but none are consistently effective. It seems likely that there are different types of cramp that are initiated by different mechanisms; if this is the case, the search for a single strategy for prevention or treatment is unlikely to succeed.

Electrolyte beverage consumption alters electrically induced cramping threshold

BACKGROUND

Recent investigations have questioned the role of hydration and electrolytes in cramp susceptibility and thus the efficacy of consuming electrolyte-rich carbohydrate beverages (EB) to control/prevent cramping.

METHODS

Nine euhydrated, cramp-prone participants had their cramp susceptibility assessed by measuring the nerve stimulation threshold frequency at which cramping occurs (TF) before and after consumption of an EB (kCal: 120, Na: 840 mg, K: 320 mg, Mg: 5 mg) and placebo beverage (PB: kCal: 5, Na: 35 mg). Cramp intensity was assessed using a verbal pain scale and poststimulation electromyography (EMG).

RESULTS

TF was greater in EB (14.86 ± 7.47 Hz) than PB (14.00 ± 5.03 Hz; P = .038) and reported pain was lower in EB (2.0 ± 0.6) than PB (2.7 ± 0.8; P = .025) while EMG was similar (P = .646).

DISCUSSION

EB consumption decreased cramp susceptibility and pain but did not prevent cramping in any participants. These results suggest that electrolyte consumption independent of hydration can influence cramp susceptibility in young people.

Proper Hydration During Ultra-endurance Activities

The health and performance of ultra-endurance athletes is dependent on avoidance of performance limiting hypohydration while also avoiding the potentially fatal consequences of exercise-associated hyponatremia due to overhydration. In this work, key factors related to maintaining proper hydration during ultra-endurance activities are discussed. In general, proper hydration need not be complicated and has been well demonstrated to be achieved by simply drinking to thirst and consuming a typical race diet during ultra-endurance events without need for supplemental sodium. As body mass is lost from oxidation of stored fuel, and water supporting the intravascular volume is generated from endogenous fuel oxidation and released with glycogen oxidation, the commonly promoted hydration guidelines of avoiding body mass losses of >2% can result in overhydration during ultra-endurance activities. Thus, some body mass loss should occur during prolonged exercise, and appropriate hydration can be maintained by drinking to the dictates of thirst.

Muscular cramp: causes and management

Muscular cramp is a common symptom in healthy people, especially among the elderly and in young people after vigorous or peak exercise. It is prominent in a number of benign neurological syndromes. It is a particular feature of chronic neurogenic disorders, especially amyotrophic lateral sclerosis. A literature review was undertaken to understand the diverse clinical associations of cramp and its neurophysiological basis, taking into account recent developments in membrane physiology and modulation of motor neuronal excitability. Many aspects of cramping remain incompletely understood and require further study. Current treatment options are correspondingly limited.

Effects of TRPV1 and TRPA1 activators on the cramp threshold frequency: a randomized, double-blind placebo-controlled trial

PURPOSE

Previous data indicate that a strong sensory input from orally administered TRPV1 and TRPA1 activators alleviates muscle cramps in foot muscles by reducing the α-motor neuron hyperexcitability. We investigated if TRP activators increase the cramp threshold frequency of the medial gastrocnemius.

METHODS

We randomly assigned 22 healthy male participants to an intervention (IG) and a control group (CG). While participants of the IG ingested a mixture of TRPV1 and TRPA1 activators, the CG received a placebo. We tested the cramp threshold frequency (CTF), the cramp intensity (EMG activity), and the perceived pain of electrically induced muscle cramps before (pre), and 15 min, 4, 8, and 24 h after either treatment. We further measured the maximal isometric force of knee extensors at pre, 4, and 24 h to assess potential side-effects on the force output.

RESULTS

When we included all measurement time points, no group-by-time interaction was observed for the CTF. However, when only pre and 15 min values were incorporated, a significant interaction, with a slightly greater CTF increase in IG (3.1 ± 1.5) compared to the CG (2.0 ± 1.5), was observed. No significant group by time interaction was found for the cramp intensity, the perceived pain, and the maximal isometric force.

CONCLUSION

Our data indicate that orally administered TRPV1 and TRPA1 activators exert a small short-term effect on the CTF, but not on the other parameters tested. Future studies need to investigate whether such small CTF increments are sufficient to prevent exercise-associated muscle cramps.

Are Electrically Induced Muscle Cramps Able to Increase the Cramp Threshold Frequency, When Induced Once a Week?

The cramp threshold frequency (CTF) is known to be positively correlated with the individual cramp susceptibility. Here we assessed CTF changes after two bouts of electrically induced muscle cramps (EIMCs). The EIMCs (6×5 sec) were unilaterally induced twice (separated by one week) in the gastrocnemius of an intervention group (n=8), while 5 participants served as control. The CTF increased from 25.1±4.6 Hz at baseline to 31.4±9.0 Hz and 31.7±8.5 Hz 24 h after bout 1 and 2 (P<0.05). Thereafter, the CTF declined following both bouts to reach values of 28.0±6.7 Hz and 29.1±7.7 Hz after 72 h after bout 1 and 2. Creatine kinase (CK) activity and perceived discomfort during cramps was lower after bout 2 (P<0.05). CTF, CK, and discomfort did not change in CG. That is, a single bout of EIMCs induces a 24 h CTF increment and a second bout sustains this effect, while perceived discomfort and muscle damage decreases. This short term effect may help athletes to reduce the cramp susceptibility for an important match.

Electrolyte and plasma responses after pickle juice, mustard, and deionized water ingestion in dehydrated humans

CONTEXT

Some athletes ingest pickle juice (PJ) or mustard to treat exercise-associated muscle cramps (EAMCs). Clinicians warn against this because they are concerned it will exacerbate exercise-induced hypertonicity or cause hyperkalemia. Few researchers have examined plasma responses after PJ or mustard ingestion in dehydrated, exercised individuals.

OBJECTIVE

To determine if ingesting PJ, mustard, or deionized water (DIW) while hypohydrated affects plasma sodium (Na(+)) concentration ([Na(+)]p), plasma potassium (K(+)) concentration ([K(+)]p), plasma osmolality (OSMp), or percentage changes in plasma volume or Na(+) content.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 9 physically active, nonacclimated individuals (age = 25 ± 2 years, height = 175.5 ± 9.0 cm, mass = 78.6 ± 13.8 kg).

INTERVENTION(S)

Participants exercised vigorously for 2 hours (temperature = 37°C ± 1°C, relative humidity = 24% ± 4%). After a 30-minute rest, a baseline blood sample was collected, and they ingested 1 mL/kg body mass of PJ or DIW. For the mustard trial, participants ingested a mass of mustard containing a similar amount of Na(+) as for the PJ trial. Postingestion blood samples were collected at 5, 15, 30, and 60 minutes.

MAIN OUTCOME MEASURE(S)

The dependent variables were [Na(+)]p, [K(+)]p, OSMp, and percentage change in plasma Na(+) content and plasma volume.

RESULTS

Participants became 2.9% ± 0.6% hypohydrated and lost 96.8 ± 27.1 mmol (conventional unit = 96.8 ± 27.1 mEq) of Na(+), 8.4 ± 2 mmol (conventional unit = 8.4 ± 2 mEq) of K(+), and 2.03 ± 0.44 L of fluid due to exercise-induced sweating. They ingested approximately 79 mL of PJ or DIW or 135.24 ± 22.8 g of mustard. Despite ingesting approximately 1.5 g of Na(+) in the PJ and mustard trials, no changes occurred within 60 minutes postingestion for [Na(+)]p, [K(+)]p, OSMp, or percentage changes in plasma volume or Na(+) content (P > .05).

CONCLUSIONS

Ingesting a small bolus of PJ or large mass of mustard after dehydration did not exacerbate exercise-induced hypertonicity or cause hyperkalemia. Consuming small volumes of PJ or mustard did not fully replenish electrolytes and fluid losses. Additional research on plasma responses pre-ingestion and postingestion to these treatments in individuals experiencing acute EAMCs is needed.

Muscle Cramping During a 161-km Ultramarathon: Comparison of Characteristics of Those With and Without Cramping

BACKGROUND

This work sought to identify characteristics differing between those with and without muscle cramping during a 161-km ultramarathon.

METHODS

In this observational study, race participants underwent body weight measurements before, during, and after the race; completed a post-race questionnaire about muscle cramping and "near" cramping (controllable, not reaching full-blown cramping), drinking strategies, and use of sodium supplementation during four race segments; and underwent a post-race blood draw for determination of serum sodium and blood creatine kinase (CK) concentrations.

RESULTS

The post-race questionnaire was completed by 280 (74.5 %) of the 376 starters. A post-race blood sample was provided by 181 (61.1 %) of the 296 finishers, and 157 (53.0 %) of finishers completed the post-race survey and also provided a post-race blood sample. Among those who completed the survey, the prevalence of cramping and near cramping was 14.3 and 26.8 %, respectively, with greatest involvement being in the calf (54 %), quadriceps (44 %), and hamstring (33 %) muscles. Those with cramping or near cramping were more likely to have a prior history of muscle cramping during an ultramarathon (p < 0.0001) and had higher blood CK concentrations (p = 0.001) than those without cramping. Weight change during the race, use of sodium supplements, intake rate of sodium in supplements, and post-race serum sodium concentration did not differ between those with and without cramping.

CONCLUSIONS

Muscle cramping is most common in those with a prior history of cramping and greater muscle damage during an ultramarathon, suggesting an association with relative muscular demand. Impaired fluid and sodium balance did not appear to be an etiology of muscle cramping during an ultramarathon.

Plasma and electrolyte changes in exercising humans after ingestion of multiple boluses of pickle juice

CONTEXT

Twenty-five percent of athletic trainers administer pickle juice (PJ) to treat cramping. Anecdotally, some clinicians provide multiple boluses of PJ during exercise but warn that repeated ingestion of PJ may cause hyperkalemia. To our knowledge, no researchers have examined the effect of ingesting multiple boluses of PJ on the same day or the effect of ingestion during exercise.

OBJECTIVE

To determine the short-term effects of ingesting a single bolus or multiple boluses of PJ on plasma variables and to characterize changes in plasma variables when individuals ingest PJ and resume exercise.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Nine euhydrated men (age = 23 ± 4 years, height = 180.9 ± 5.8 cm, mass = 80.7 ± 13.8 kg, urine specific gravity = 1.009 ± 0.005).

INTERVENTION(S)

On 3 days, participants rested for 30 minutes, and then a blood sample was collected. Participants ingested 0 or 1 bolus (1 mL · kg(-1) body weight) of PJ, donned sweat suits, biked vigorously for 30 minutes (approximate temperature = 37 °C, relative humidity = 18%), and had a blood sample collected. They either rested for 60 seconds (0- and 1-bolus conditions) or ingested a second 1 mL · kg(-1) body weight bolus of PJ (2-bolus condition). They resumed exercise for another 35 minutes. A third blood sample was collected, and they exited the environmental chamber and rested for 60 minutes (approximate temperature = 21 °C, relative humidity = 18%). Blood samples were collected at 30 and 60 minutes postexercise.

MAIN OUTCOME MEASURE(S)

Plasma sodium concentration, plasma potassium concentration, plasma osmolality, and changes in plasma volume.

RESULTS

The number of PJ boluses ingested did not affect plasma sodium concentration, plasma potassium concentration, plasma osmolality, or changes in plasma volume over time. The plasma sodium concentration, plasma potassium concentration, and plasma osmolality did not exceed 144.6 mEq · L(-1) (144.6 mmol · L(-1)), 4.98 mEq · L(-1) (4.98 mmol · L(-1)), and 289.5 mOsm · kg(-1)H2O, respectively, in any condition at any time.

CONCLUSIONS

Ingesting up to 2 boluses of PJ and resuming exercise caused negligible changes in blood variables. Ingesting up to 2 boluses of PJ did not increase plasma sodium concentration or cause hyperkalemia.

The Governor has a sweet tooth - mouth sensing of nutrients to enhance sports performance

The oral-pharyngeal cavity and the gastrointestinal tract are richly endowed with receptors that respond to taste, temperature and to a wide range of specific nutrient and non-nutritive food components. Ingestion of carbohydrate-containing drinks has been shown to enhance endurance exercise performance, and these responses have been attributed to post-absorptive effects. It is increasingly recognised, though, that the response to ingested carbohydrate begins in the mouth via specific carbohydrate receptors and continues in the gut via the release of a range of hormones that influence substrate metabolism. Cold drinks can also enhance performance, especially in conditions of thermal stress, and part of the mechanism underlying this effect may be the response to cold fluids in the mouth. There is also some, albeit not entirely consistent, evidence for effects of caffeine, quinine, menthol and acetic acid on performance or other relevant effects. This review summarises current knowledge of responses to mouth sensing of temperature, carbohydrate and other food components, with the goal of assisting athletes to implement practical strategies that make best use of its effects. It also examines the evidence that oral intake of other nutrients or characteristics associated with food/fluid intake during exercise can enhance performance via communication between the mouth/gut and the brain.

A promising approach to effectively reduce cramp susceptibility in human muscles: a randomized, controlled clinical trial

Background

To investigate if the cramp threshold frequency (CTF) can be altered by electrical muscle stimulation in a shortened position.

Methods

A total of 15 healthy male sport students were randomly allocated to an intervention (IG, n = 10) and a non-treatment control group (CG, n = 5). Calf muscles of both legs in the IG were stimulated equally twice a week over 6 weeks. The protocol was 3×5 s on, 10 s off, 150 µs impulse width, 30 Hz above the individual CTF, and was at 85% of the maximal tolerated stimulation energy. One leg was stimulated in a shortened position, inducing muscle cramps (CT), while the opposite leg was fixated in a neutral position at the ankle, hindering muscle cramps (nCT). CTF tests were performed prior to the first and 96 h after the 6^th (3 w) and 12^th (6 w) training session.

Results

After 3 w, the CTF had significantly (p<0.001) increased in CT calves from 23.3±5.7 Hz to 33.3±6.9 Hz, while it remained unchanged in nCT (pre: 23.6±5.7 Hz, mid: 22.3±3.5 Hz) and in both legs of the CG (pre: 21.8±3.2 Hz, mid: 22.0±2.7 Hz). Only CT saw further insignificant increases in the CTF. The applied stimulation energy (mA² • µs) positively correlated with the effect on the CTF (r = 0.92; p<0.001).

Conclusions

The present study may be useful for developing new non-pharmacological strategies to reduce cramp susceptibility.

Trial Registry

German Clinical Trials Register DRKS00005312

Pre-exercise ingestion of pickle juice, hypertonic saline, or water and aerobic performance and thermoregulation

CONTEXT

Ingesting high-sodium drinks pre-exercise can improve thermoregulation and performance. Athletic trainers (19%) give athletes pickle juice (PJ) prophylactically for cramping. No data exist on whether this practice affects aerobic performance or thermoregulation.

OBJECTIVE

To determine if drinking 2 mL/kg body mass of PJ, hypertonic saline, or deionized water (DIW) pre-exercise affects aerobic performance or thermoregulation.

DESIGN

Crossover study.

SETTING

Controlled laboratory study.

PATIENTS OR OTHER PARTICIPANTS

Nine euhydrated men (age = 22 ± 3 years, height = 184.0 ± 8.2 cm, mass = 82.6 ± 16.0 kg) completed testing.

INTERVENTION(S)

Participants rested for 65 minutes. During this period, they ingested 2 mL/kg of PJ, hypertonic saline, or DIW. Next, they drank 5 mL/kg of DIW. Blood was collected before and after ingestion of all fluids. Participants were weighed and ran in the heat (temperature = 38.3°C ± 1°C, relative humidity = 21.1% ± 4.7%) at increasing increments of maximal heart rate (50%, 60%, 70%, 80%, 90%, 95%) until exhaustion or until rectal temperature exceeded 39.5°C. Participants were weighed postexercise so we could calculate sweat volume.

MAIN OUTCOME MEASURE(S)

Time to exhaustion, rectal temperature, changes in plasma volume, and sweat volume.

RESULTS

Time to exhaustion did not differ among drinks (PJ = 77.4 ± 5.9 minutes, hypertonic saline = 77.4 ± 4.0 minutes, DIW = 75.7 ± 3.2 minutes; F2,16 = 1.1, P = .40). Core temperature of participants was similar among drinks (PJ = 38.7°C ± 0.3°C, hypertonic saline = 38.7°C ± 0.4°C, DIW = 38.8°C ± 0.4°C; P = .74) but increased from pre-exercise (36.7°C ± 0.2°C) to postexercise (38.7°C ± 0.4°C) (P < .05). No differences were observed for changes in plasma volume or sweat volume among drinks (P > .05).

CONCLUSIONS

Ingesting small amounts of PJ or hypertonic saline with water did not affect performance or select thermoregulatory measures. Drinking larger volumes of PJ and water may be more effective at expanding the extracellular space.

Ad libitum fluid intake and plasma responses after pickle juice, hypertonic saline, or deionized water ingestion

CONTEXT

Adding sodium (Na(+)) to drinks improves rehydration and ad libitum fluid consumption. Clinicians (∼25%) use pickle juice (PJ) to treat cramping. Scientists warn against PJ ingestion, fearing it will cause rapid plasma volume restoration and thereby decrease thirst and delay rehydration. Advice about drinking PJ has been developed but never tested.

OBJECTIVE

To determine if drinking small volumes of PJ, hypertonic saline (HS), or deionized water (DIW) affects ad libitum DIW ingestion, plasma variables, or perceptual indicators.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Fifteen, euhydrated (urine specific gravity ≤ 1.01) men (age = 22 ± 2 years, height = 178 ± 6 cm, mass = 82.9 ± 8.4 kg).

INTERVENTION(S)

Participants completed 3 testing days (≥ 72 hours between days). After a 30-minute rest, a blood sample was collected. Participants completed 60 minutes of hard exercise (temperature = 36 ± 2°C, relative humidity = 16 ± 1%). Postexercise, they rested for 30 minutes; had a blood sample collected; rated thirst, fullness, and nausea; and ingested 83 ± 8 mL of PJ, HS, or DIW. They rated drink palatability (100-mm visual analog scale) and were allowed to drink DIW ad libitum for 60 minutes. Blood samples and thirst, fullness, and nausea ratings (100-mm visual analog scales) were collected at 15, 30, 45, and 60 minutes posttreatment drink ingestion.

MAIN OUTCOME MEASURE(S)

Ad libitum DIW volume, percentage change in plasma volume, plasma osmolality (OSMp,) plasma sodium concentration ([Na(+)]p), and thirst, fullness, nausea, and palatability ratings.

RESULTS

Participants consumed more DIW ad libitum after HS (708.03 ± 371.03 mL) than after DIW (532.99 ± 337.14 mL, P < .05). Ad libitum DIW ingested after PJ (700.35 ± 366.15 mL) was similar to that after HS and DIW (P > .05). Plasma sodium concentration, OSMp, percentage change in plasma volume, thirst, fullness, and nausea did not differ among treatment drinks over time (P > .05). Deionized water (73 ± 14 mm) was more palatable than HS (17 ± 13 mm) or PJ (26 ± 16 mm, P < .05).

CONCLUSIONS

The rationale behind advice about drinking PJ is questionable. Participants drank more, not less, after PJ ingestion, and plasma variables and perceptual indicators were similar after PJ and DIW ingestion. Pickle juice did not inhibit short-term rehydration.

Gastric emptying after pickle-juice ingestion in rested, euhydrated humans

CONTEXT

Small volumes of pickle juice (PJ) relieve muscle cramps within 85 seconds of ingestion without significantly affecting plasma variables. This effect may be neurologic rather than metabolic. Understanding PJ's gastric emptying would help to strengthen this theory.

OBJECTIVE

To compare gastric emptying and plasma variables after PJ and deionized water (DIW) ingestion.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Ten men (age  =  25.4 ± 0.7 years, height  =  177.1 ± 1.6 cm, mass  =  78.1 ± 3.6 kg).

INTERVENTION(S)

Rested, euhydrated, and eunatremic participants ingested 7 mL·kg⁻¹ body mass of PJ or DIW on separate days.

MAIN OUTCOME MEASURE(S)

Gastric volume was measured at 0, 5, 10, 20, and 30 minutes postingestion (using the phenol red dilution technique). Percentage changes in plasma volume and plasma sodium concentration were measured preingestion (-45 minutes) and at 5, 10, 20, and 30 minutes postingestion.

RESULTS

Initial gastric volume was 624.5 ± 27.4 mL for PJ and 659.5 ± 43.8 mL for DIW (P > .05). Both fluids began to empty within the first 5 minutes (volume emptied: PJ  =  219.2 ± 39.1 mL, DIW  =  305.0 ± 40.5 mL, P < .05). Participants who ingested PJ did not empty further after the first 5 minutes (P > .05), whereas in those who ingested DIW, gastric volume decreased to 111.6 ± 39.9 mL by 30 minutes (P < .05). The DIW group emptied faster than the PJ group between 20 and 30 minutes postingestion (P < .05). Within 5 minutes of PJ ingestion, plasma volume decreased 4.8% ± 1.6%, whereas plasma sodium concentration increased 1.6 ± 0.5 mmol·L⁻¹ (P < .05). Similar changes occurred after DIW ingestion. Calculated plasma sodium content was unchanged for both fluids (P > .05).

CONCLUSIONS

The initial decrease in gastric volume with both fluids is likely attributable to gastric distension. Failure of the PJ group to empty afterward is likely due to PJ's osmolality and acidity. Cardiovascular reflexes resulting from gastric distension are likely responsible for the plasma volume shift and rise in plasma sodium concentration despite nonsignificant changes in plasma sodium content. These data support our theory that PJ does not relieve cramps via a metabolic mechanism.