Expressing the quantity of urinary analytes: a discussion of some issues arising from the monitoring of the menstrual cycle

Practical domestic monitoring of the menstrual cycle requires measurements of urinary metabolites of reproductive hormones: oestrone glucuronide (E1G) and pregnanediol glucuronide (PdG). Data reported in the literature are expressed as (i) concentration, without or with either creatinine- or specific gravity correction, or (ii) excretion rates. This variation in such a fundamental issue prompts consideration of the relationships between the four measures. Because the menstrual cycle kinetics of E1G and PdG are complex, we consider measurements of urinary creatinine, urea, galactose, xylose and inulin which tend to be more stable. We show that uncorrected concentration measurements of these urinary analytes can be positively correlated, negatively correlated or uncorrelated with the serum concentration. Based on measurements of urinary creatinine concentrations, urinary specific gravity and creatinine excretion rates, we conclude that urinary analyte concentration are likely to be more reliable when creatinine-corrected rather than corrected using specific gravity, but that both are less reliable than measurements of the excretion rate. This has implications for the quantitation of any urinary analyte, but especially for the monitoring of the menstrual cycle in which changes in E1G and PdG from one day to the next can be physiologically significant for a woman monitoring her fertility.

Evaluation of Pragmatic Methods to Rapidly Assess Habitual Beverage Intake and Hydration Status in U.S. Collegiate Athletes

Fluid intake recommendations have been established for the athletic population in order to promote adequate hydration. The Beverage Intake Questionnaire (BEVQ-15) is a quick and reliable food frequency questionnaire that quantifies habitual beverage intake, which has been validated in children, adolescents, and adults. However, no validated beverage consumption questionnaire is available for collegiate athletes. Urine color (UC), while feasible for determining hydration status, has not been validated within a variety of collegiate athletes. The purpose of this investigation was to evaluate the comparative validity and reliability of pragmatic methods to rapidly assess BEVQ-15 and UC rating in U.S. Division I collegiate athletes. Student-athletes (n = 120; 54% females; age 19 ± 1 years) from two universities were recruited to complete three study sessions. At the first and third sessions, the participants completed the BEVQ-15 and provided a urine sample to determine UC and urinary specific gravity. All sessions included completion of a 24-hr dietary recall. Total fluid intake (fl oz) was 111 ± 107 and 108 ± 42 using the BEVQ-15 and the mean of three 24-hr dietary recalls, respectively, which was not different between methods (p > .05). There were moderate associations between the BEVQ-15 and dietary recall results for total beverage intake fl oz and kcal(r = .413 and r = 4.65; p ≤ .05, respectively). Strong associations were noted between both researcher-rated and participant-rated UC with urinary specific gravity measures (r = .675 and r = .884; p ≤ .05, respectively). Therefore, these rapid assessment methods demonstrated acceptable validity and may be used as practical methods to determine whether athletes are meeting their hydration recommendations.

Effects of Dehydration on Cognitive and Physical Performance in Female Golfers: A Randomized Crossover Pilot Study

Athletes’ commitments to nutrition practices can set them apart in their field. Few studies have investigated the impact of hydration practices on golfers’ performance who compete for up to eight hours a day, and none have studied female golfers. In this pilot, randomized crossover study, female elite golfers (n = 6) completed 4 simulated golf holes in both euhydrated and dehydrated states. Euhydration was attained by following NCAA (National Collegiate Athletic Association) hydration guidelines; dehydration was attained by a 12-h overnight fluid fast. Before any fluid intervention, five out of six participants were dehydrated at baseline using urinary specific gravity (USG) classifications for euhydration (USG < 1.010) and dehydration (USG > 1.010). No significant condition by time interactions were found between hydration conditions. Although not significant, participants in a dehydrated state demonstrated lesser mean 7-iron distance (141.9 ± 10.0 vs 144.2 ± 8.0 m), lower putting accuracy (2.4 ± 1.0 vs 2.7 ± 10.0 putts made out of 4 attempts), and greater perceived effort (10.9 ± 2.1 vs 10.5 ± 1.6) as compared to their euhydrated state. The finding of one participant out of six with significant dehydration (USG = 1.021) during attempted euhydrated state may suggest the need for alternative methods to promote adequate hydration in future studies and possibly in golf practice.

Effects of Playing Position on Hydration Status in Collegiate Marching Band Musicians

OBJECTIVE: Marching band musicians often endure prolonged daily practices in warm-hot outdoor environments. Evaluation of hydration status by instrument position can shed light on health-related issues for these performers. The objective of this study was: a) to determine the effects of playing position on hydration status based on urinary biomarkers (urinary specific gravity and urinary osmolality) before and after marching band practice, and b) to evaluate the relation of hydration status with body mass change and fluid consumption for all playing positions. METHODS: Fifty-eight collegiate marching band players participated in this study, involving five playing positions: band pit (n=10), baritone and euphonium (n=12), snare drum (n=13), trumpet (n=12), and tuba (n=11). All participants performed their own routine marching band practice, which lasted a total of 6 hrs on 1 day. Each individual consumed ad libitum commercially available carbohydrate-electrolyte solution during the practice. To determine hydration status, urine samples were collected before and after practice for analysis of urinary specific gravity and urinary osmolality. Body weight and total fluid intake were also assessed pre- and post-exercise. RESULTS: There were no significant effects for playing position and time or interaction concerning the levels of urinary osmolality and specific gravity after practice. CONCLUSIONS: Our main findings suggest that hydration status may be similar among the different playing positions following prolonged practice in the outdoor environment.

Monitoring Athletes during Training Camps: Observations and Translatable Strategies from Elite Road Cyclists and Swimmers

Monitoring is an essential yet unstandardized component of managing athletic preparation. The purpose of this paper is to provide insight into the typical measurements and responses observed from monitoring elite road cyclist and swimmers during training camps, and translate these observations to practical strategies for other practitioners to employ. Twenty-nine male professional cyclists, 12 male and 19 female international swimmers participated in up to three of the eight 4–19 day training camps, held early in the season or leading into major competitions, at sea-level or moderate altitude. Monitoring included body mass and composition, subjective sleep, urinary specific gravity (USG), resting heart rate (HR) and peripheral oxygen saturation (SpO2) at altitude. Sum of seven skinfolds most likely decreased in the order of 3.1 ± 3.6 mm week-to-week, accompanied by a most likely trivial decrease in body mass of 0.4 ± 0.4 kg week-to-week. At altitude, sleep quality very likely trivially improved week-to-week (0.3 ± 0.3 AU), SpO2 possibly increased week-to-week (0.6 ± 1.7%), whilst changes in resting HR were unclear (0 ± 4 bpm). Sleep duration and USG were stable. Comparing individual to group day-to-day change in monitored variables may prove effective to flag athletes potentially at risk of training maladaptation. Practitioners may replicate these methods to establish thresholds specific to their cohort and setting. This study provides further support for a multi-faceted approach to monitoring elite athletes in training camp environments.