Habitual Fluid Intake Does Not Affect Sleep Parameters in Young Women.

Sleep is essential for optimal physical performance, cognitive function, recovery, and overall health. Similarly, hydration status has been shown to influence physical and cognitive functions. Dehydration can lead to impaired cognition and possibly impaired sleep. However, the effect of habitual total water intake (TWI) on sleep and recovery measures have not been examined. PURPOSE: To examine the effect of TWI on sleep and recovery measures in young women. METHODS: Twenty-two young women (age: 22.8±4.6 yrs; body mass: 60.0±9.5 kg; height: 164.6±6.1 cm) collected fluid intake and food consumption information across a 5 day period, and average TWI was calculated based on them. Then, participants were categorized in either High Drinker (HD; ³ 2.5L/day; n=13; age: 23.0±3.6 yrs) or Low Drinker (LD; £ 1.6 L/day; n=9; age: 23±3yrs). Sleep and recovery measures were collected using a wearable sleep-tracking device that participants wore for 5 consecutive days. Sleep and recovery measures were compared between HD and LD, using a two-tailed independent t-test and effect sizes (ES). ES were identified as either small (0.2-0.49), medium (0.5-0.79), and large (\u3e0.8). RESULTS: No significant differences were found in resting heart rate (HD: 63.7±4.6 bpm, LD: 61.9± 5.2 bpm; p=0.40), heart rate variability (HD: 58.2±14.1 ms, 69.6±40.9 ms; p=0.44), slow wave sleep (SWS) (HD: 1.5±0.4 hrs, LD: 1.4±0.3 hrs; p=0.55), SWS percentage (HD: 19.3±3.8 %, LD: 18.7±3.7 %; p=0.17) sleep consistency (HD: 65.2±15.6 %, LD: 63.3±7. 3%; p=0.71), and sleep efficiency (HD: 90.5±3.1 %, LD: 90.4±2.0 %; p=0.91). While there were no statistical differences, rapid eye movement (REM) sleep (HD: 2.0±0.4 hrs, LD: 1.6±0.7 hrs; p=0.17) and REM percentage (HD: 26.1±3.8 %, LD: 21.5±7.8 %; p=0.13) displayed the largest differences, with REM indicating a medium ES (d=0.70) and REM percentage having a large ES (d=0.80). CONCLUSION: Habitual fluid intake might not impact sleep measurement. However, based on ES, REM sleep and REM percentage potentially display a trend. Still, more research is necessary to further determine any correlations

Impact of Habitual Water Intake on Muscle Quality and Total Body Water-A Pilot Study

Proper hydration is essential for critical health and performance functions, such as muscle function and body fluid balance. The effect of acute hydration status has been studied on health and muscle performance; however, the effect of habitual water intake on muscle quality and total body water between high and low consumption has not been examined. PURPOSE: To determine the impact of habitual water intake on muscle quality and total body water. METHODS: Eleven women (age: 27.6±7.9 years; mass: 60.3±10.8 kg) provided a five-day dietary food log to categorize them into HIGH or LOW daily total water intake (TWI). TWI values \u3e2.5-3.3 L/day (HIGH) or \u3c 0.7-1.6 L/day (LOW) were used to determine groups. Bioelectrical impedance analysis (BIA) and ultrasound images were obtained to assess overall muscle quality and total body fluid balance between the two groups. Analysis of ultrasound images using ImageJ determined length (cm), cross-sectional area (CSA), and muscle quality through echo intensity (EI) of the participant’s right and left rectus femoris (RF). An independent sample T-Test and effect sizes (ES) were used to assess differences between HIGH and LOW. RESULTS: Due to this study being a pilot study, there was no significant differences in right RF length between LOW (1.44±0.22 cm) and HIGH (1.22±0.24 cm, p=0.153) with a large effect size of (ES=0.98). There were no significant differences in left RF length (p=0.861) between HIGH (1.46±0.28 cm) and LOW (1.42±0.32) groups with a trivial effect size (ES=0.11). Right RF CSA had non-significant differences between LOW (3.72±1.18 cm2) and HIGH (2.95±1.05 cm2, p=0.309) with medium effect (ES=0.68). There were no differences in CSA-left between HIGH (3.63 ± 1.06 cm) and LOW (3.83±1.44, p=0.816, ES=0.15). Right RF muscle quality also had a medium effect size (ES=0.78) between HIGH (135.30±21.82 A.U) and LOW (117.71±23.10 A.U). Muscle quality of the left RF had a small effect size (ES=0.26) between LOW (118.29±22.18 A.U) and HIGH (125.97±39.47 A.U, p=0.684). While there was no statistical difference due to the power (p=0.163), total body water (TBW) percentage (%) was greater in HIGH (53.9±1.5%) compared to LOW (50.6±5.4%, ES= 0.75) with medium effects. HIGH and LOW demonstrated no statistical difference (p=0.579) with a small effect size (ES=0.36) between ECF% and ICF%, respectively (41.00±0.72%, 41.39±1.20%; 59.00±0.72%, 58.61±1.20%). CONCLUSION: Despite no significant differences, based on ES, HIGH habitual water intake increases TBW% than LOW. Further data must be collected to draw definitive conclusions; however, these results suggest skeletal muscle quality is high with LOW habitual water intake

The Effect of Hydration on Readiness and Recovery Before and After Resistance Exercise- A Pilot Study

Dehydration can disturb sleep which is essential for the readiness and recovery process. However, the role of hydration on readiness and recovery indicated by low resting heart rate (RHR) and high heart rate variability (HRV) before and after resistance exercise (RE) is not known. PURPOSE: The purpose of this study was to examine the effect of hydration status on readiness and recovery before and after RE. METHODS: Seven resistance-trained men (age: 21±1 years; weight: 77.8±11.0 kg; height: 177.4±5.3 cm) performed a series of RE that included bilateral leg press and knee extensions (5 sets of 10 repetitions at 80% of 1 repetition maximum). Participants completed the same RE twice with 2 weeks in between. Participants completed one trial in a euhydrated state (EUH; urine specific gravity (USG) \u3c 1.020) and the other in a dehydrated state (DEH: USG ≥ 1.020). For the DEH trial, participants were restricted from consuming fluids for 24 hours prior to the RE and were only permitted to drink 1.5 L of water post-exercise for the remainder of the day. For the EUH trial, participants were instructed to consume fluid throughout the day before and the day of RE to maintain euhydration. Data was collected from a wearable sleep device that participants wore to determine recovery by assessing RHR and HRV. Repeated measures ANOVAs were used to identify the differences, and effect size (ES), resulting effects identified as either small (0.2-0.49), medium (0.5-0.79), or large (\u3e0.8) effects, was calculated. RESULTS: There were no differences in RHR between EUH and DEH on the night before (EUH, 63±13 bpm; DEH, 61±11 bpm; ES=0.16) and after RE (EUH, 59±14 bpm; DEH, 58±9 bpm; ES=0.12; p=0.806). No significant difference was found in recovery between EUH and DEH on the night before (EUH, 37±30 au; DEH, 39±25 au; ES=0.05) or the night after (EUH, 38±29 au; DEH, 42±22 au; ES=0.42; p=0.821) RE. HRV were not different between EUH and DEH on the night before (EUH, 55±27 ms; DEH, 60±32 ms; ES=0.16) and after (EUH, 67±38 ms; DEH, 71±23 ms; ES=0.12; p=0947). CONCLUSION: This pilot study showed hydration status did not impact readiness and recovery before and after RE. However, this could be because the few participants resulted in a low statistical power. Therefore, further studies with more participants could be conducted to better determine how hydration affects readiness and recovery