provide a greater benefit to thermal perception thereby driving behavioral thermoregulation. Our data suggest that only TS was significantly improved although TC did alter subjectively in the hypothesized direction. The performance change through perceptual mechanisms did not manifest itself through
Martin J. Barwood, Joe Kupusarevic and Stuart Goodall
Ben T. Stephenson, Sven P. Hoekstra, Keith Tolfrey and Victoria L. Goosey-Tolfrey
finite literature concerning thermoregulation in Paralympic sport has centered on athletes with a spinal cord injury (SCI) due to their high propensity for thermal strain caused by impaired autonomic function and therefore sudomotor and vasomotor control. 2 Research has characterized the
M.J. Anderson, J.D. Cotter, A.P. Garnham, D.J. Casley and M.A. Febbraio
This study examined the effect of glycerol ingestion on fluid homeostasis, thermoregulation, and metabolism during rest and exercise. Six endurance-trained men ingested either 1 g glycerol in 20 ml H2O · kg−1 body weight (bw) (GLY) or 20 ml H2O · kg−1 bw (CON) in a randomized double-blind fashion, 120 min prior to undertaking 90 min of steady state cycle exercise (SS) at 98% of lactate threshold in dry heat (35 °C, 30% RH), with ingestion of CHO-electrolyte beverage (6% CHO) at 15-min intervals. A 15-min cycle, where performance was quantified in kJ, followed (PC). Pre-exercise urine volume was lower in GLY than CON (1119 ± 97 vs. 1503 ± 146 ml · 120 min−1; p < .05). Heart rate was lower (p < .05) throughout SS in GLY, while forearm blood flow was higher (17.1 ± 1.5 vs. 13.7 ± 3.0 ml · 100 g tissue · min−1; < .05) and rectal temperature lower (38.7 ± 0.1 vs. 39.1 ± 0.1 °C; p < .05) in GLY late in SS. Despite these changes, skin and muscle temperatures and circulating catecholamines were not different between trials. Accordingly, no differences were observed in muscle glycogenolysis, lactate accumulation, adenine nucleotide, and phosphocreatine degradation or inosine 5′-monophosphate accumulation when comparing GLY with CON. Of note, the work performed during PC was 5% greater in GLY (252 ± 10 vs. 240 ± 9 kJ;p < .05). These results demonstrate that glycerol, when ingested with a bolus of water 2 hours prior to exercise, results in fluid retention, which is capable of reducing cardiovascular strain and enhancing thermoregulation. Furthermore, this practice increases exercise performance in the heat by mechanisms other than alterations in muscle metabolism.
Catriona A. Burdon, Helen T. O’Connor, Janelle A. Gifford and Susan M. Shirreffs
Increased core temperature (Tc), impaired cardiovascular function, and dehydration contribute to fatigue during prolonged exercise in the heat. Although many studies have examined mechanisms addressing these factors, few have investigated the effect of cold beverage temperature on thermoregulation and exercise performance in the heat.
Citations from MEDLINE (Ovid), Sport Discus (EBSCOhost), AUSPORT and AusportMed (Informit), Web of Science, and SCOPUS were identified from the earliest record until September 2008 using the search terms drink temperature, beverage temperature, fluid temperature, water temperature, and cold fluid combined with body temperature and thermoregulation. To be included, studies needed to assess core or rectal temperature during exercise in moderate or hot environmental conditions. After quality rating was completed by two reviewers, the difference in mean Tc and exercise performance was calculated.
Ten studies meeting search inclusion criteria were available for analysis. Three were excluded because sufficient detail or statistical data were not reported. A meta-analysis was not performed because the studies were deemed too different to group. Three of the remaining 7 studies found modulated Tc with cold beverage consumption, and from the 4 that conducted exercise performance tests, performance improved by 10% with cold fluids.
Cold fluid may attenuate Tc rise and improve exercise performance in the heat; however, study findings are mixed. Research using well-trained athletes and fluid-ingestion protocols replicating competition scenarios is required. Potential sensory effects of cold fluid in maintaining motivation also need to be assessed as a mechanism underpinning improved performance.
Michael J. Zurawlew, Jessica A. Mee and Neil P. Walsh
additional exercise. As sleeping patterns can influence thermoregulation, 1 participants were instructed to sleep between 2200 and 0700 hours to ensure a similar circadian pattern prior to each experimental trial. This was confirmed by monitoring sleep, using an ActiGraph worn on the nondominant arm with
Cody R. Smith, Cory L. Butts, J.D. Adams, Matthew A. Tucker, Nicole E. Moyen, Matthew S. Ganio and Brendon P. McDermott
thermoregulation, blood flow to the periphery increases, perfusing sweat glands for efficient sweat evaporation. 7 However, when the skin is cooled, skin blood flow is decreased as a result of vasoconstriction. 24 This phenomenon also likely occurs with effective cooling modalities like cold-water immersion, but
Susan Y. Kwiecien, Malachy P. McHugh, Stuart Goodall, Kirsty M. Hicks, Angus M. Hunter and Glyn Howatson
.1249/MSS.0000000000001756 30095750 32. Kaciuba-Uscilko H , Grucza R . Gender differences in thermoregulation . Curr Opin Clin Nutr Metab Care . 2001 ; 4 : 533 – 536 . PubMed ID: 11706289 doi:10.1097/00075197-200111000-00012 10.1097/00075197-200111000-00012 11706289
W. Larry Kenney
Katy E. Griggs, Christof A. Leicht, Michael J. Price and Victoria L. Goosey-Tolfrey
Individuals with a spinal-cord injury have impaired thermoregulatory control due to a loss of sudomotor and vasomotor effectors below the lesion level. Thus, individuals with high-level lesions (tetraplegia) possess greater thermoregulatory impairment than individuals with lower-level lesions (paraplegia). Previous research has not reflected the intermittent nature and modality of wheelchair court sports or replicated typical environmental temperatures. Hence, the purpose of this study was to investigate the thermoregulatory responses of athletes with tetraplegia and paraplegia during an intermittent-sprint protocol (ISP) and recovery in cool conditions.
Sixteen wheelchair athletes, 8 with tetraplegia (TP, body mass 65.2 ± 4.4 kg) and 8 with paraplegia (body mass 68.1 ± 12.3 kg), completed a 60-min ISP in 20.6°C ± 0.1°C, 39.6% ± 0.8% relative humidity on a wheelchair ergometer, followed by 15 min of passive recovery. Core temperature (T core) and mean (T sk) and individual skin temperatures were measured throughout.
Similar external work (P = .70, ES = 0.20) yet a greater T core (P < .05, ES = 2.27) and T sk (P < .05, ES = 1.50) response was demonstrated by TP during the ISP.
Despite similar external work, a marked increase in Tcore in TP during exercise and recovery signifies that thermoregulatory differences between the groups were predominantly due to differences in heat loss. Further increases in thermal strain were not prevented by the active and passive recovery between maximal-effort bouts of the ISP, as T core continually increased throughout the protocol in TP.
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.