Erica T. Perrier

Efficacy of tart cherry juice in reducing muscle pain during running: a randomized controlled trial

BackgroundLong distance running causes acute muscle damage resulting in inflammation and decreased force production. Endurance athletes use NSAIDs during competition to prevent or reduce pain, which carries the risk of adverse effects. Tart cherries, rich in antioxidant and anti-inflammatory properties, may have a protective effect to reduce muscle damage and pain during strenuous exercise. This study aimed to assess the effects of tart cherry juice as compared to a placebo cherry drink on pain among runners in a long distance relay race.MethodsThe design was a randomized, double blind, placebo controlled trial. Fifty-four healthy runners (36 male, 18 female; 35.8 ± 9.6 yrs) ran an average of 26.3 ± 2.5 km over a 24 hour period. Participants ingested 355 mL bottles of tart cherry juice or placebo cherry drink twice daily for 7 days prior to the event and on the day of the race. Participants assessed level of pain on a standard 100 mm Visual Analog Scale (VAS) at baseline, before the race, and after the race.ResultsWhile both groups reported increased pain after the race, the cherry juice group reported a significantly smaller increase in pain (12 ± 18 mm) compared to the placebo group (37 ± 20 mm) (p < .001). Participants in the cherry juice group were more willing to use the drink in the future (p < 0.001) and reported higher satisfaction with the pain reduction they attributed to the drink (p < 0.001).ConclusionsIngesting tart cherry juice for 7 days prior to and during a strenuous running event can minimize post-run muscle pain.

The Acute Effects of a Warm-up Including Static or Dynamic Stretching on Countermovement Jump Height, Reaction Time, and Flexibility

Perrier, ET, Pavol, MJ, and Hoffman, MA. The acute effects of a warm-up including static or dynamic stretching on countermovement jump height, reaction time, and flexibility. J Strength Cond Res 25(7): 1925-1931, 2011—The purpose of this research was to compare the effects of a warm-up with static vs. dynamic stretching on countermovement jump (CMJ) height, reaction time, and low-back and hamstring flexibility and to determine whether any observed performance deficits would persist throughout a series of CMJs. Twenty-one recreationally active men (24.4 ± 4.5 years) completed 3 data collection sessions. Each session included a 5-minute treadmill jog followed by 1 of the stretch treatments: no stretching (NS), static stretching (SS), or dynamic stretching (DS). After the jog and stretch treatment, the participant performed a sit-and-reach test. Next, the participant completed a series of 10 maximal-effort CMJs, during which he was asked to jump as quickly as possible after seeing a visual stimulus (light). The CMJ height and reaction time were determined from measured ground reaction forces. A treatment × jump repeated-measures analysis of variance for CMJ height revealed a significant main effect of treatment (p = 0.004). The CMJ height was greater for DS (43.0 cm) than for NS (41.4 cm) and SS (41.9 cm) and was not less for SS than for NS. Analysis also revealed a significant main effect of jump (p = 0.005) on CMJ height: Jump height decreased from the early to the late jumps. The analysis of reaction time showed no significant effect of treatment. Treatment had a main effect (p < 0.001) on flexibility, however. Flexibility was greater after both SS and DS compared to after NS, with no difference in flexibility between SS and DS. Athletes in sports requiring lower-extremity power should use DS techniques in warm-up to enhance flexibility while improving performance.

Twenty-Four-Hour Urine Osmolality as a Physiological Index of Adequate Water Intake

While associations exist between water, hydration, and disease risk, research quantifying the dose-response effect of water on health is limited. Thus, the water intake necessary to maintain optimal hydration from a physiological and health standpoint remains unclear. The aim of this analysis was to derive a 24 h urine osmolality (UOsm) threshold that would provide an index of “optimal hydration,” sufficient to compensate water losses and also be biologically significant relative to the risk of disease. Ninety-five adults (31.5 ± 4.3 years, 23.2 ± 2.7 kg·m−2) collected 24 h urine, provided morning blood samples, and completed food and fluid intake diaries over 3 consecutive weekdays. A UOsm threshold was derived using 3 approaches, taking into account European dietary reference values for water; total fluid intake, and urine volumes associated with reduced risk for lithiasis and chronic kidney disease and plasma vasopressin concentration. The aggregate of these approaches suggest that a 24 h urine osmolality ≤500 mOsm·kg−1 may be a simple indicator of optimal hydration, representing a total daily fluid intake adequate to compensate for daily losses, ensure urinary output sufficient to reduce the risk of urolithiasis and renal function decline, and avoid elevated plasma vasopressin concentrations mediating the increased antidiuretic effort.

Fluid Intake and Vasopressin: Connecting the Dots

In the last decade, cross-sectional and multiple cohort studies have associated total fluid intake or water intake with the risk for chronic kidney disease (CKD) and even the risk of developing hyperglycemia. Urine biomarkers have also been linked to the risk of CKD and lithiasis, and these biomarkers respond quickly to variations in fluid intake. High circulating copeptin levels, a surrogate marker of arginine vasopressin, have been associated with metabolic syndrome, renal dysfunction and increased risk for diabetes mellitus, cardiovascular disease and death. The aim of this paper was to explore how the various findings on water intake, hydration and health are interconnected, to highlight current gaps in our understanding and to propose a model that links water intake, homeostatic mechanisms to maintain water balance and health outcomes. Since plasma copeptin and vasopressin have been demonstrated to be sensitive to changes in water intake, inversely associated with 24-hour urine volume, and associated with urine biomarkers and fluid intake, vasopressin is proposed as the central player in this theoretical physiological model.

Shifting Focus: From Hydration for Performance to Hydration for Health

Over the past 10 years, literature on hydration biomarkers has evolved considerably - from (de)hydration assessment towards a more global definition of biomarkers of hydration in daily life. This shift in thinking about hydration markers was largely driven by investigating the differences that existed between otherwise healthy individuals whose habitual, ad-libitum drinking habits differ, and by identifying physiological changes in low-volume drinkers who subsequently increase their water intake. Aside from obvious differences in urinary volume and concentration, a growing body of evidence is emerging that links differences in fluid intake with small, but biologically significant, differences in vasopressin (copeptin), glomerular filtration rate, and markers of metabolic dysfunction or disease. Taken together, these pieces of the puzzle begin to form a picture of how much water intake should be considered adequate for health, and represent a shifting focus from hydration for performance, toward hydration for health outcomes. This narrative review outlines the key areas of research in which the global hydration process - including water intake, urinary hydration markers, and vasopressin - has been associated with health outcomes, focusing on kidney and metabolic endpoints. It will also provide a commentary on how various hydration biomarkers may be used in hydration for health assessment. Finally, if adequate water intake can play a role in maintaining health, how might we tell if we are drinking enough? Urine output is easily measured, and can take into account differences in daily physical activity, climate, dietary solute load, and other factors that influence daily water needs. Today, targets have been proposed for urine osmolality, specific gravity, and color that may be used by researchers, clinicians, and individuals as simple indicators of optimal hydration. However, there remain a large number of incomplete or unanswered research questions regarding the relationships between water intake, hydration, vasopressin, and health outcomes. Thus, this emerging field represents an excellent opportunity, particularly for young researchers, to develop relevant and novel lines of research.

Assessing a Tool for Self-Monitoring Hydration Using Urine Color in Pregnant and Breastfeeding Women: A Cross-Sectional, Online Survey

Background: Pregnant and breastfeeding women experience great changes in their total body water content and water dynamics. To support the accretion of total body water during pregnancy and compensate for the water lost through breast milk during breastfeeding, increased adequate intakes (AI) for total water have been established by various health authorities. Despite this widespread advice, several studies suggest that pregnant and breastfeeding women do not meet the AI for total water, suggesting the need to raise womens awareness on the importance of adequate water intake, particularly during pregnancy and breastfeeding, as well as to provide them with a simple means of monitoring their hydration on a day-to-day basis. A urine color (UC) scale recently has been validated for hydration monitoring in pregnant and breastfeeding women. Summary: We sought to develop a version of a tool based on the UC scale, using only images or illustrations, which could be understood by users of various nationalities and spoken languages. Pregnant and breastfeeding women (n = 1,275) from Brazil, Mexico, and Poland were shown 3 versions of the tool. Understanding, appreciation, simplicity and intent to use were evaluated using a questionnaire consisting of 26 items. Key Messages: Among the 3 versions tested, one tool emerged as the most highly understood (88% spontaneous understanding) and was highly appreciated by users (mean [SD]: 8.40 [2.20] out of 10). There were no differences between countries. Furthermore, 83% reported being very likely to use the tool daily. These results suggest that a simple tool based on the UC scale will help pregnant and breastfeeding women meet the AI for total water.