title: Effects of obesity and mild hypohydration on local sweating and cutaneous vascular responses during passive heat stress in females.
abstract: The purpose of this study was to evaluate the effect of obesity and mild hypohydration on local sweating (LSR) and cutaneous vascular conductance (CVC) responses during passive heat stress in females. Thirteen obese (age, 24 ± 4 years; 45.4% ± 5.2% body fat) and 12 nonobese (age, 22 ± 2 years; 25.1% ± 3.9% body fat) females were passively heated (1.0 °C rectal temperature increase) while either euhydrated (EUHY) or mildly hypohydrated (HYPO; via fluid restriction). Chest and forearm LSR (ventilated capsule) and CVC (Laser Doppler flowmetry) onset, sensitivity, and plateau/steady state were recorded as mean body temperature increased (ΔTb). Participants began trials EUHY (urine specific gravity, Usg = 1.009 ± 0.006) or HYPO (Usg = 1.025 ± 0.004; p < 0.05), and remained EUHY or HYPO. Independent of obesity, HYPO decreased sweat sensitivity at the chest (HYPO = 0.79 ± 0.35, EUHY = 0.95 ± 0.39 Δmg·min(-1)·cm(-2)/°C ΔTb) and forearm (HYPO = 0.82 ± 0.39, EUHY = 1.06 ± 0.34 Δmg·min(-1)·cm(-2)/°C ΔTb); forearm LSR plateau was also decreased (HYPO = 0.66 ± 0.19, EUHY = 0.78 ± 0.23 mg·min(-1)·cm(-2); all p < 0.05). Overall, obese females had lower chest-sweat sensitivity (0.72 ± 0.35 vs. 1.01 ± 0.33 Δmg·min(-1)·cm(-2)/°C ΔTb) and plateau (0.55 ± 0.27 vs. 0.80 ± 0.25 mg·min(-1)·cm(-2); p < 0.05). While hypohydrated, obese females had a lower chest LSR (p < 0.05) versus nonobese females midway (0.45 ± 0.26 vs. 0.73 ± 0.23 mg·min(-1)·cm(-2)) and at the end (0.53 ± 0.27 vs. 0.81 ± 0.24 mg·min(-1)·cm(-2)) of heating. Furthermore, HYPO (relative to the EUHY trials) led to a greater decrease in CVC sensitivity in obese (-28 ± 27 Δ% maximal CVC/°C ΔTb) versus nonobese females (+9.2 ± 33 Δ% maximal CVC/°C ΔTb; p < 0.05). In conclusion, mild hypohydration impairs females' sweating responses during passive heat stress, and this effect is exacerbated when obese.
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Nicole E
authors.initials: NE
authors.lastname: Moyen
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Jenna M
authors.initials: JM
authors.lastname: Burchfield
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Cory L
authors.initials: CL
authors.lastname: Butts
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Jordan M
authors.initials: JM
authors.lastname: Glenn
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Tucker
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Keeley
authors.initials: K
authors.lastname: Treece
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Amber J
authors.initials: AJ
authors.lastname: Smith
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Brendon P
authors.initials: BP
authors.lastname: McDermott
authors.affiliation: Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.|Human Performance Laboratory, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Ganio
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015992:Body Mass Index; D001831:Body Temperature; D003681:Dehydration / Q000503:physiopathology*; D015444:Exercise; D005260:Female; D006358:Hot Temperature; D006801:Humans; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply*; D013312:Stress, Physiological; D011795:Surveys and Questionnaires; D013545:Sweat Glands / Q000502:physiology; D013546:Sweating; D055815:Young Adult
keywords: body fat; dehydration; débit sanguin cutané; déshydratation; femmes; gras corporel; skin blood flow; sudation; sweating; women