title: Using gait parameters to detect fatigue and responses to ice slurry during prolonged load carriage.
abstract: This study examined (1) if changes in gait characteristics could indicate the exertional heat stress experienced during prolonged load carriage, and (2) if gait characteristics were responsive to a heat mitigation strategy. In an environmental chamber replicating tropical climatic conditions (ambient temperature 32°C, 70% relative humidity), 16 males aged 21.8 (1.2) years performed two trials of a work-rest cycle protocol consisting two bouts of 4-km treadmill walks with 30-kg load at 5.3km/h separated by a 15-min rest period. Ice slurry (ICE) or room temperature water (29°C) as a control (CON) was provided in 200-ml aliquots. The fluids were given 10min before the start, at the 15(th) and 30(th) min of each work cycle, and during each rest period. Spatio-temporal gait characteristics were obtained at the start and end of each work-rest cycle using a floor-based photocell system (OptoGait) and a high-speed video camera at 120Hz. Repeated-measure analysis of variance (trial×time) showed that with time, step width decreased (p=.024) while percent crossover steps increased (p=.008) from the 40(th) min onwards. Reduced stance time variability (-11.1%, p=.029) step width variability (-8.2%, p=.001), and percent crossover step (-18.5%, p=.010) were observed in ICE compared with CON. No differences in step length and most temporal variables were found. In conclusion, changes in frontal plane gait characteristics may indicate exertional heat stress during prolonged load carriage, and some of these changes may be mitigated with ice slurry ingestion.
authors.affiliation: Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, 637616, Singapore.
authors.forename: Cheryl S
authors.initials: CS
authors.lastname: Tay
authors.affiliation: Combat Protection and Performance Programme, Defence Medical and Environmental Research Institute, DSO National Laboratories, 20 Science Park Drive, 118230, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, 119228, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Novena Campus, 11 Mandalay Road, 308232, Singapore.
authors.forename: Jason K W
authors.initials: JK
authors.lastname: Lee
authors.affiliation: Combat Protection and Performance Programme, Defence Medical and Environmental Research Institute, DSO National Laboratories, 20 Science Park Drive, 118230, Singapore.
authors.forename: Ya S
authors.initials: YS
authors.lastname: Teo
authors.affiliation: Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, 637616, Singapore.
authors.forename: Phildia Q Z
authors.initials: PQ
authors.lastname: Foo
authors.affiliation: Combat Protection and Performance Programme, Defence Medical and Environmental Research Institute, DSO National Laboratories, 20 Science Park Drive, 118230, Singapore.
authors.forename: Pearl M S
authors.initials: PM
authors.lastname: Tan
authors.affiliation: Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, 637616, Singapore. Electronic address: puiwah.kong@nie.edu.sg.
authors.forename: Pui W
authors.initials: PW
authors.lastname: Kong
mesh_terms: D005221:Fatigue / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006358:Hot Temperature; D006801:Humans; D007053:Ice; D008297:Male; D014867:Water; D014937:Work; D055815:Young Adult
chemical_list: D007053:Ice; D014867:Water
keywords: Fatigue; Heat; Step width; Variability; Walking