Abbreviations: BSA, body surface area; CON, control; ht = height; N/A, not available; PC, precooling; RH, relative humidity; RPE, rating of perceived exertion; T core , body core temperature; T skin , skin temperature; TS, thermal sensation. Note: All data are reported as mean (SD); data were rounded to the
Timothy M. Wohlfert and Kevin C. Miller
Catriona A. Burdon, Matthew W. Hoon, Nathan A. Johnson, Phillip G. Chapman and Helen T. O’Connor
The purpose of this study was to establish whether sensory factors associated with cold-beverage ingestion exert an ergogenic effect on endurance performance independent of thermoregulatory or cardiovascular factors.
Ten males performed three trials involving 90 min of steady state cycling (SS; 62% VO2max) in the heat (32.1 ± 0.9 °C, 40 ± 2.4% relative humidity) followed by a 4 kJ/kg body mass time trial (TT). During SS, participants consumed an identical volume (260 ± 38g) of sports beverage (7.4% carbohydrate) every 15 min as either ice slushy (–1 °C; ICE), thermoneutral liquid (37 °C; CON), or thermoneutral liquid consumption with expectorated ice slushy mouthwash (WASH).
Rectal temperature, hydration status, heart rate, and skin blood flow were not different between trials. Gastrointestinal (pill) temperature was lower in ICE (35.6 ± 2.7 °C) versus CON (37.4 ± 0.7 °C, p = .05). Heat storage tended to be lower with ICE during SS (14.7 ± 8.4W.m−2, p = .08) and higher during TT (68.9 ± 38.6W.m−2, p = .03) compared with CON (22.1 ± 6.6 and 31.4 ± 27.6W.m−2). ICE tended to lower the rating of perceived exertion (RPE, 12.9 ± 0.6, p = .05) and improve thermal comfort (TC, 4.5 ± 0.2; p = .01) vs. CON (13.8 ± 1.0 and 5.2 ± 0.2 respectively). WASH RPE (13.0 ± 0.8) and TC (4.8 ± 0.2) tended to be lower versus CON (p = .07 and p = .09 respectively). ICE improved performance (18:28 ± 1:03) compared with CON (20:24 ± 1:46) but not WASH (19:45 ± 1:43).
Improved performance with ICE ingestion likely resulted from the creation of a gastrointestinal heat sink, reducing SS heat storage. Although the benefits of cold-beverage consumption are more potent when there is ingestion, improved RPE, TC, and meaningful performance improvement with WASH supports an independent sensory effect of presenting a cold stimulus to the mouth.
Kayla E. Boehm and Kevin C. Miller
higher. Exclusion • Studies that did not test both male and female subjects or differentiate cooling rates by gender. • Studies that measured body core temperature by oral, axillary, esophageal, tympanic, or temporal thermometry. • Studies that cooled hyperthermic subjects by other means (eg
Matt B. Brearley and James P. Finn
Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available.
To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.
Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index.
Prerace body-core temperatures were (mean ± SD) 37.7°C ± 0.4°C (range 37.0°C to 38.2°C), rising to 39.0°C ± 0.4°C (range 38.4°C to 39.7°C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 ± 0.12 L/h or 13.4 ± 1.2 mL · kg−1 · h−1, and postrace dehydration was 0.6% ± 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 ± 0.9), thermal discomfort as uncomfortable (3.1 ± 1.0), and perceived exertion as very hard to very, very hard (8.7 ± 1.7) after the races. Overall physiological and perceptual strain were 7.4 ± 1.0 and 7.1 ± 1.2, respectively.
Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.
Thomas Reeve, Ralph Gordon, Paul B. Laursen, Jason K.W. Lee and Christopher J. Tyler
impulse must exceed a critical threshold, 3 and this may explain the small physiological adaptation seen in the current study. Although individual variation exists, time spent with core temperatures ≥38.5°C may be required for heat adaptation, 12 and the highest mean body core temperature recorded in
Sarah Kölling, Rob Duffield, Daniel Erlacher, Ranel Venter and Shona L. Halson
initiated through a reduced body core temperature which is achieved by elevating the distal skin temperature, 6 another prebedtime routine could be a warm shower to reduce sleep-onset latency. 39 The environmental temperature, on the other hand, should be preferably rather cool instead of warm. Sleep
Cody R. Smith, Cory L. Butts, J.D. Adams, Matthew A. Tucker, Nicole E. Moyen, Matthew S. Ganio and Brendon P. McDermott
4. Castle PC , Maxwell N , Allchorn A , Mauger AR , White DK . Deception of ambient and body core temperature improves self paced cycling in hot, humid conditions . Eur J Appl Physiol . 2012 ; 112 ( 1 ): 377 – 385 . PubMed doi:10.1007/s00421-011-1988-y 10.1007/s00421-011-1988-y
David P. Looney, Mark J. Buller, Andrei V. Gribok, Jayme L. Leger, Adam W. Potter, William V. Rumpler, William J. Tharion, Alexander P. Welles, Karl E. Friedl and Reed W. Hoyt
In healthcare and in general living conditions body core temperature (CT) is considered one of the most informative indicators of thermal stress ( Montain, Sawka, Cadarette, Quigley, & McKay, 1994 ; Sawka et al., 2001 ), a key indicator in thermal comfort ( Gagge et al., 1967 ), and has a wide
Matthew Zimmermann, Grant Landers, Karen Wallman and Georgina Kent
. PubMed doi:10.1111/sms.12629 10.1111/sms.12629 26677824 19. Byrne C , Lim CL . The ingestible telemetric body core temperature sensor: a review of validity and exercise applications . Br J Sports Med . 2007 ; 41 ( 3 ): 126 – 133 . PubMed doi:10.1136/bjsm.2006.026344 17178778 10.1136/bjsm.2006
Michael J. Davies, Bradley Clark, Laura A. Garvican-Lewis, Marijke Welvaert, Christopher J. Gore and Kevin G. Thompson
( 3 ): 534 – 541 . PubMed ID: 21886012 doi:10.1249/MSS.0b013e318232cf77 10.1249/MSS.0b013e318232cf77 21886012 9. Castle PC , Maxwell N , Allchorn A , Mauger AR , White DK . Deception of ambient and body core temperature improves self paced cycling in hot, humid conditions . Eur J Appl