title: Sweating responses to isometric hand-grip exercise and forearm muscle metaboreflex in prepubertal children and elderly.
abstract: What is the central question of this study? Non-thermal factors (e.g. muscle metaboreflex) contribute to the sweating response during exercise. Although it is well recognized that the sweating responses caused by core temperature elevation in prepubertal children and the elderly are attenuated compared with young adults, it is unknown whether non-thermal sweating is also attenuated in these populations. What is the main finding and its importance? The non-thermal sweating response during isometric hand-grip exercise and isolated muscle metaboreflex were attenuated in prepubertal children compared with young adults in a non-uniform manner over the body, but only during the muscle metaboreflex in the elderly. This may explain the maturation- and ageing-related decline of sweating during exercise. The purpose of the present study was to investigate sweating responses to isometric hand-grip (IH) exercise and muscle metaboreflex in prepubertal children and the elderly. In hot conditions (ambient temperature, 35°C; relative humidity, 45%), 13 healthy young adults, 10 prepubertal children and 10 elderly subjects (aged 20.4 ± 1.2, 11.4 ± 0.5 and 63.5 ± 3.1 years, respectively) repeated a three hand-grip exercise protocol that consisted of 1 min IH exercise at 15, 30 or 45% of maximal voluntary contraction (MVC) followed by 2 min postexercise forearm occlusion. Local sweat rates (SRs) on the forehead, chest, forearm, thigh and palm were continuously measured (ventilated capsule method). The forehead SR in prepubertal children during IH exercise at 45% MVC was significantly lower than that of young adults (0.26 ± 0.22 and 0.08 ± 0.15 mg cm-2min-1for young adults and children, respectively; P < 0.05) but not of the elderly at any exercise intensities. The SR on the chest (0.22 ± 0.22 and -0.01 ± 0.05 mg cm-2min-1for young adults and children, respectively), forearm (0.14 ± 0.12 and 0.03 ± 0.04 mg cm-2min-1) and thigh (0.13 ± 0.10 and 0.02 ± 0.03 mg cm-2min-1) during postexercise occlusion at 45% MVC was significantly lower in children than in young adults (P < 0.05). Elderly subjects showed a significantly lower SR on the forearm (0.04 ± 0.04 and 0.01 ± 0.02 mg cm-2min-1for young adults and elderly, respectively) and thigh (0.07 ± 0.07 and 0.01 ± 0.03 mg cm-2min-1) at 15% MVC and on the thigh at 45% MVC (0.13 ± 0.10 and 0.04 ± 0.04 mg cm-2min-1) during postexercise occlusion compared with young adults (P < 0.05). These results suggest that sweating responses to IH exercise and muscle metaboreflex were underdeveloped in prepubertal children and that ageing attenuates the response to the muscle metaboreflex in a way that is not consistent across the body.
authors.affiliation: Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan.|Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Amano
authors.affiliation: Laboratory for Human Performance Research, Osaka International University, Osaka, Japan.
authors.forename: Seiko
authors.initials: S
authors.lastname: Kai
authors.affiliation: Laboratory for Human Performance Research, Osaka International University, Osaka, Japan.
authors.forename: Michi
authors.initials: M
authors.lastname: Nakajima
authors.affiliation: Laboratory for Human Performance Research, Osaka International University, Osaka, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ichinose-Kuwahara
authors.affiliation: Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan.
authors.forename: Nicola
authors.initials: N
authors.lastname: Gerrett
authors.affiliation: Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan.
authors.forename: Narihiko
authors.initials: N
authors.lastname: Kondo
authors.affiliation: Laboratory for Human Performance Research, Osaka International University, Osaka, Japan.
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology; D002648:Child; D015444:Exercise / Q000502:physiology*; D005542:Forearm / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D012018:Reflex / Q000502:physiology*; D013546:Sweating / Q000502:physiology*; D055815:Young Adult
keywords: eccrine sweat gland; exercise pressor reflex; thermoregulation