EFFECT OF SPACER GARMENT ON PHYSIOLOGICAL STRAIN DURING EXERCISE IN THE HEAT WHEN WEARING PROTECTIVE VESTS

J.D. Adams, Brendon P. McDermott, Christian B. Ridings, Lacey Mainer, Matthew S. Ganio, and Stavros A. Kavouras, FACSM. Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, AR.; email: [email protected] Numerous cooling technologies have been developed to reduce heat strain when wearing a variety of protective ensembles during military and law enforcement duties. Some cooling vests demonstrate improved sweat evaporation and decreased core temperature when worn along with protective body armor. Spacer garments represent a potentially lighter, cost-efficient method for improved airflow. PURPOSE: To determine if a spacer garment reduces physiological strain during exercise in the heat when wearing a military protective vest or a law enforcement concealable vest. METHODS: Sixteen men (24.5 ± 3.9 yrs.; 179.5 ± 5.6 cm; 84.6 ± 12.3 kg) performed either 2 or 4 trials of treadmill walking (3.1 mph; 2% grade) over 120 min in a hot, dry environment (37°C, 30% rh, wind speed 3.5 m·s). Participants completed trials with either a military patrol vest or a law enforcement concealable vest, with either a spacer garment (Ps; Cs) or no spacer garment (Pc; Cc) in random order. During trials, participants wore Army Combat Uniform pants and physiological measurements that were measured every 5 min included gastrointestinal temperature (TGI), mean skin (Tsk) temperature, heart rate (HR), and sweating rate (SR). RESULTS: In the patrol trial (Ps vs. Pc), no differences in final TGI (38.2 ± 0.4 vs. 38.3 ± 0.4°C), Tsk (35.0 ± 0.9 vs. 35.0 ± 1.0 °C), HR (142 ± 19 vs. 143 ± 23 bpm), or SR (1.15 ± 1.13 vs. 1.54 ± 0.46 L/hr) existed (P\u3e0.05). In the concealable trial (Cs vs. Cc), no differences in final TGI (38.0 ± 0.4 vs. 38.1 ± 0.3°C), Tsk (35.3 ± 1.1 vs. 35.6 ± 0.9°C), HR (132 ± 20 vs. 135 ± 20 bpm), or SR (1.39 ± 0.52 vs.1.37 ± 0.18 L/hr) existed (P\u3e0.05). CONCLUSION: When participants exercised with either a military protective vest or a law enforcement concealable vest while wearing the spacer garment, there were no thermoregulatory differences when compared to control trials. Thus, the passive spacer garment had no effect on the physiological responses during mild exercise in the heat. Funded by Cortac

VALIDITY OF UCHEK IPHONE APPLICATION ON ASSESSING DEHYDRATION FROM URINE SAMPLES

1Christian B. Ridings, 1J.D. Adams, 1Matthew S. Ganio, 1Brendon P. McDermott, 2Dimitris Bougatsas, 1Stavros A. Kavouras, FACSM. 1Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, AR; 2Laboratory of Nutrition & Clinical Dietetics, Harokopio University, Athens, Greece The widespread acceptance of smartphones presents an opportunity for the development of mobile health applications and accessories. These devices can help reduce costs and improve accessibility of healthcare. PURPOSE: To determine the validity of the uChek iPhone application on measuring hydration status compared to urine refractometry and urine dipstick applicators. METHODS: Fifty-three urine samples were analyzed for urine specific gravity (USG) by a refractometer under a well-lit area. Urine strips (Multistix 10 SG Reagent Strips) were used to record USG by the Multistix label compared to an 8-color control stick, and was then analyzed by the uChek application. RESULTS: Sensitivity analysis showed that overall accuracy of USG via strips and uChek were 68 and 67.3%, respectively. Specifically, the sensitivity of a positive urine test for dehydration (USG≥1.020) was 55.6% with the strips and 51.9% with the iPhone app. The specificity for detecting hypohydrated persons was 36.4% and 31.8% for the strips and iPhone app, respectively. CONCLUSION: We concluded that the iPhone application uChek is not accurately detecting dehydration mainly due to limitations of the urine strips

HYDRATION BIOMARKERS: CREATING A NEW HYDRATION ASSESSMENT TECHNIQUE

Jenna M. Burchfield, Matthew S. Ganio, Stavros A. Kavouras, FACSM, J. D. Adams1, Melina A. Gonzalez, & Christian B. Ridings; 1Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas Despite the necessity of euhydration, an optimal, user-friendly, accurate hydration assessment technique fails to exist for the general population. PURPOSE: The purpose of this study was to investigate a new hydration assessment technique, which utilizes no equipment or technical expertise to administer. We hypothesized that the number of urine voids over a 24-hr time period correlates to hydration status. METHODS: Forty-seven healthy individuals (n=24 females) participated (age 22±4 years, body mass 76±17 kg, height 1.64±0.27 m, body fat 20.4±8.7%). Participants abstained from caffeine and alcohol during the experiment. Participants were educated on how to record diet, fluid intake, and void output measurements. For 24-hours participants voided at a normal urge into a standard medical-grade container. Participants indicated volume, time, and urge of each void. Ad libitum fluid and food intake also were recorded over the 24 hrs. Total 24-hr urine volume, osmolality, specific gravity (USG), and color were measured. Subjects were classified as euhydrated (USG≤1.020) or hypohydrated (USG\u3e1.020) according to standard criteria. RESULTS: Euhydrated (n=41) versus dehydrated (n=6) individuals had more voids (6±2 versus 4±1, respectively, P=0.02), greater 24-hr urine volume (2007±863 versus 1193±434 ml, P\u3c0.001), lower urine color (2±1 versus 4±1, P\u3c0.001), lower USG (1.012±0.004 versus 1.023±0.003, P\u3c0.001), and lower osmolality (431±143 versus 841±137 mOsm/kgH20, P\u3c0.001). As hypothesized, void number moderately correlated to hydration status as identified by USG (r=0.37, P\u3c0.001), and osmolality (r=0.38, P\u3c0.001). CONCLUSION: Void number positively correlated with USG and urine osmolality. This indicates that individuals with higher void numbers are more hydrated than those with lower void numbers over a 24-hr time period. Using void number as a hydration biomarker could be an optimal technique for the general public to self-assess hydration, considering it is as simple as counting void numbers over a 24-hr period. Funding provided by the University of Arkansas College of Education & Health Professions and the Office of Research & Economic Development

EFFECTS OF BREATHING COOL AIR DURING EXERCISE IN THE HEAT ON THERMOREGULATION, PERCEPTION AND CYCLING PERFORMANCE

Cory L. Butts, Brendon P. McDermott, Christian B. Ridings, Elizabeth M. Demartini, James Grant, Nicole E. Moyen, Jenna M. Burchfield, Matthew S. Ganio & Stavros A. Kavouras, FACSM University of Arkansas, Fayetteville, Arkansas Limited research exists investigating the physiological effects of breathing cold air during exercise as a method of attenuating increases in core temperature. PURPOSE: Determine the effects of breathing cooled air during exercise on physiological, perceptual and subsequent performance responses. METHODS: Twelve trained male cyclists (age 26.5±3.6 y, height 1.81±0.05 m, body mass 73.5±7.9 kg, body fat 13.7±7.0%, VO2max 57.6±7.9 ml/kg/min) completed three trials in an environmental chamber (31°C, 55% RH) consisting of 75 min cycling at 59.1±4.8% VO2max, a performance 5 km time trial, and a 15 min cool down. Participants breathed on:off the CoreCooler device (water bottle providing cold air) at a low intermittent (LI) ratio of 1:4 min with inspired air temperature (TIA) of 19.8±3.7°C, high intermittent (HI) ratio of 2.5:2.5 min (TIA, 19.4±4.2°C), or control (CN) breathing warm air at 1:4 min (TIA, 30.8±1.6°C) during cycling and cool down. Gastrointestinal temperature (TGI), heart rate (HR), blood pressure (BP), perceived thirst, thermal sensation, and rating of perceived exertion (RPE) were collected every 15 min during cycling and every 5 min during performance and cool down. RESULTS: No differences were found in TGI (p=.827), HR (p=.363), MAP (p=.055), Thirst (p=.140), RPE (p=.056) between conditions at any time points. The rate of rise in core temperature was not attenuated in LI (0.014±0.005°C/min, p=1.00) or HI (0.008±0.005°C/min, p=.10) compared with CN (0.013±0.005°C/min). Systolic BP was greater at 45 minutes of cycling in HI (193.8±20.7 mmHg) versus CN (176.1±15.6 mmHg, p= .039). Thermal sensation was lower in LI than CN at the end of performance (CN 6.7±0.7, LI 6.0±0.7, p=.039) and both LI (CN 4.3±0.8, LI 3.8±0.7, p=.006) and HI (HI 3.7±0.7, p=.006) were lower at the end of cool down. Performance times were not different following LI (23.7±4.2 min, p=.279) or HI (23.6±4.2 min, p=.192) compared to CN (24.6±3.9 min). CONCLUSION: The utilization of the CoreCooler device at both LI and HI frequencies decreased thermal sensation, however no differences in physiological responses or performance were identified. This research was funded by CoreCooler Company, LLC

Somatic mutation of immunoglobulin VH6 genes in human infants

Infants respond to antigen by making antibody that is generally of low affinity for antigen. Somatic hypermutation of immunoglobulin genes, and selection of cells expressing mutations with improved affinity for antigen, are the molecular and cellular processes underlying the maturation of antibody affinity. We have reported previously that neonates and infants up to 2 months of age, including individuals undergoing strong immunological challenge, show very few mutated VH6 sequences, with low mutation frequencies in mutated sequences, and little evidence of selection. We have now examined immunoglobulin genes from healthy infants between 2 and 10 months old for mutation and evidence of selection. In this age group, the proportion of VH6 sequences which are mutated and the mutation frequency in mutated sequences increase with age. There is evidence of selection from 6 months old. These results indicate that the process of affinity maturation, which depends on cognate T–B cell interaction and functional germinal centres, is approaching maturity from 6 months old

Influences of Web interactivity and social identity and bonds on the quality of online discussion in a virtual community

[[abstract]]People participate in virtual communities (VCs) for knowledge sharing or social interaction. However, most studies of VCs have focused on elucidating knowledge sharing rather than predicting virtual social interactions. This study considers “quality of online discussion” an appropriate metric for assessing group-level outcomes of virtual social interactions, and thus for predicting member willingness to sustain an ongoing relationship with a virtual community (VC). This study develops a research model, grounded in Web interactivity, social identity and social bond theories, for predicting the quality of online discussion in terms of cognitive and social influences. Empirical results from an online survey of a VC verify distinct direct and indirect social influences (perceived internalization bonds and perceived identification bonds) and cognitive influences (perceived communication and perceived control). Implications for academics and practitioners are also discussed