Ice Vest Research Articles

Effect of providing cooling techniques (pre-cooling & per-cooling) on cognitive function

The implementation of cooling techniques plays a crucial role in minimizing exercise-induced hyperthermia, thereby enhancing performance and preserving cognitive function during training. However, studies on the effect of cooling techniques on cognitive function have yielded mixed results due to inconsistent methodologies, unclear implementation guidelines, variations in cooling protocols, types of exercise, different environmental temperature, and variations in subject fitness levels. Therefore, this study compared the effectiveness of different cooling techniques in improving cognitive function during high-intensity exercise. Eleven young, healthy adult men, aged 18 to 28 years, with a Body Mass Index (BMI) ranging from 18.5 to 24.9 kg/m², normal blood pressure, and a resting heart rate (RHR) between 60 and 100 bpm, were recruited for this study. This research employed a crossover design. The subjects received three types of interventions in a random order: 1) pre-cooling using an ice vest for 30 minutes before training; 2) pre-cooling by consuming an ice slushy at a dosage of 7 g/kg of body weight over 30 minutes; and 3) a combination of both methods. The washout period between interventions was 72 hours. The results indicate a significant decrease in cognitive performance in the pre-cooling and per-cooling groups, with p-values of <0.001 (pre-cooling) and 0.014 (per-cooling). In contrast, cognitive performance in the group receiving the combination of the two methods was maintained (p = 0.641). The combination of pre-cooling with an ice vest and per-cooling with an ice slushy can help maintain cognitive function after high-intensity exercise compared to using either method alone.

Ice vests extend physiological work time while wearing explosive ordnance disposal protective clothing in hot and humid conditions

BackgroundExplosive ordnance disposal (EOD) technicians may be required to work in hot, humid environments while wearing heavy protective clothing. We investigated the ability of an ice vest to attenuate physiological strain and subsequently extend work tolerance. MethodsEight male participants (24.3 ± 4.1 yr, 51.9 ± 4.6 mL kg−1 min−1) walked (4.5 km h−1) in simulated hot and humid conditions (35 °C; 50% relative humidity). Participants wore either an EOD suit (CON) or EOD and ice vest (IV). Heart rate, core and skin temperature were recorded continuously. ResultsParticipants walked longer in IV compared to CON (8.1 ± 7.4 min, p < .05). Over 90% of trials were terminated based on participants reaching 90% of their maximum heart rate. IV resulted in cooled skin (p < .001) and a physiologically negligible change in core temperature (p < .001). A condition by time interaction was identified for heart rate (p < .001), with a lower rate of rise in the IV condition. ConclusionsThe cardiovascular inefficiency that limited performance was attenuated in the IV condition. The ice vest facilitated heat loss from the periphery; thus, the observed reduction in heart rate may reflect the preservation of central blood volume. The results identify the efficiency of a simple, inexpensive ice vest to assist EOD technicians working in the heat.

Reduced serum concentrations of reactive oxygen and nitrogen species following strenuous exercise in the heat are not associ-ated with an upregulation in serum antioxidative capacity

Introduction: Reactive oxygen and nitrogen species (RONS) are produced as a response to exercise and play a part in guiding the adaptive response to physical training. Exercise in the heat has been shown to further increase accumulation of RONS in systemic circulation; however, a high anti-oxidative response or heat acclimatization mechanisms could attenuate this response. In a previous study, we found reduced RONS concentrations in trained athletes following strenuous cycling in the heat. Therefore, this secondary analysis assessed whether these reduced RONS serum con-centrations are induced by an increased serum antioxidant capacity. Methods: Twelve male cyclists (V̇O2peak: 60 ± 4 ml ∙ kg-1 ∙ min-1) completed a 60-minute constant workload trial (55% peak power output, ambient temperature 30.4 ± 0.6°C) with and without ice vest in a randomized order. The core body temperature (Tcore) was measured by an ingestible capsule. Blood samples were col-lected before and after each trial to determine superoxide dismutase (SOD) and catalase (CAT) activity, total antioxidant capacity (TAC) and RONS. Due to the absence of between-group dif-ferences, data of both conditions were pooled. Results: Tcore statistically increased (p &lt; 0.001) over the experimental trials (+6.0 ± 1.6%, effect size (ES) = 5.6). Concentrations of RONS (-17.2 ± 15.5%, p &lt; 0.001, ES = 1.0) and TAC (-8.9 ± 22.9%, p = 0.04, ES = 0.7) statistically decreased, while the activity of CAT (+15.5 ± 84.0%, p = 0.90, ES = 0.04) and SOD (+9.2 ± 58.7%, p = 0.98, ES = 0.01) remained un-changed. Conclusions: Reduced serum RONS concentrations after strenuous cycling in the heat were not associated with upregulation of serum antioxidant capacity in trained athletes. The prooxidant-antioxidant balance may rather be regulated at a myocellular level and should be further assessed in future studies.

Perceptions of Heat Stress, Heat Strain and Mitigation Practices in Wildfire Suppression across Southern Europe and Latin America.

This study aimed to assess current perceptions of heat stress, heat strain, acclimatisation and recovery practices in wildland fire suppression. A total of 1459 wildfire and structural firefighters, all involved in wildland fire suppression, completed an 18-question survey. Most participants (81.3%) reported heat strain as one of the main risks faced during wildland firefighting. Thermal strain is considered an important risk for health and safety in wildland firefighting. The best-valued heat strain mitigation strategies were those traditionally recommended in wildland fire suppression: (i) an adequate work/rest ratio (79.0%), (ii) acclimatisation (71.6%), (iii) enhancing body ventilation by opening protective clothing or removing helmets or gloves (63.5%), and (iv) drinking water and food supplementation (52.1%). Despite these results, only 22% of the participants reported carrying out acclimatisation in the workplace. The vast majority of the respondents (87.4%) consider active cooling strategies (i.e., ice slurry ingestion, ice vests, etc.) impractical in combating heat strain during wildfire suppression. We identified a gap between knowledge about heat strain, its mitigation strategies and the level of actual implementation of these practices in the workplace. Our results highlight the need to improve heat strain management and implement operational directives for acclimatisation and active cooling interventions.

Limiting Rise in Heat Load With an Ice Vest During Elite Female Rugby Sevens Warm-Ups.

To determine the effect of wearing a phase-change cooling vest in elite female rugby sevens athletes during (1) a simulated match-day warm-up in hot conditions prior to a training session and (2) a prematch warm-up during a tournament in cool conditions. This study consisted of 2 randomized independent group designs (separated by 16d) where athletes completed the same 23- to 25-minute match-day warm-up (1)in hot conditions (range = 28.0°C to 35.1°C wet bulb globe temperature [WBGT]) prior to training and (2)in cool conditions (range = 18.8°C to 20.1°C WBGT) prior to a World Rugby Women's Sevens Series match. In both conditions, athletes were randomly assigned to wearing either (1)the standardized training/playing ensemble (synthetic rugby shorts and training tee/jersey) or (2)the standardized training/playing ensemble plus a commercial phase-change athletic cooling vest. Group-wise differences in core temperature rise from baseline, global positioning system-measured external locomotive output, and perceptual thermal load were compared. Core temperature rise during a match warm-up was lower in the hot condition only (-0.65°C [95% confidence interval = -1.22°C to -0.08°C], ηp2=.23 [95% confidence interval = .00 to .51], P = .028). No differences in various external-load variables were observed. Phase-change cooling vests can be worn by athletes prior to, and during, a prematch warm-up in hot conditions to limit excess core temperature rise without adverse effects on thermal perceptions or external locomotion output.

An Ice Vest, but Not Single-Hand Cooling, Is Effective at Reducing Thermo-Physiological Strain During Exercise Recovery in the Heat.

Sports limit the length of breaks between halves or periods, placing substantial time constraints on cooling effectiveness. This study investigated the effect of active cooling during both time-limited and prolonged post-exercise recovery in the heat. Ten recreationally-active adults (VO2peak 43.6 ± 7.5 ml·kg−1·min−1) were exposed to thermally-challenging conditions (36°C air temperature, 45% RH) while passively seated for 30 min, cycling for 60 min at 51% VO2peak, and during a seated recovery for 60 min that was broken into two epochs: first 15 min (REC0−15) and total 60 min (REC0−60). Three different cooling techniques were implemented during independent recovery trials: (a) negative-pressure single hand-cooling (~17°C); (b) ice vest; and (c) non-cooling control. Change in rectal temperature (Tre), mean skin temperature (), heart rate (HR), and thermal sensation (TS), as well as mean body temperature (), and heat storage (S) were calculated for exercise, REC0−15 and REC0−60. During REC0−15, HR was lowered more with the ice vest (−9 [−15 to −3] bts·min−1, p = 0.002) and single hand-cooling (−7 [−13 to −1] bts·min−1, p = 0.021) compared to a non-cooling control. The ice vest caused a greater change in compared to no cooling (−1.07 [−2.00 to −0.13]°C, p = 0.021) and single-hand cooling (−1.07 [−2.01 to −0.14]°C, p = 0.020), as well as a greater change in S compared to no cooling (−84 [−132 to −37] W, p < 0.0001) and single-hand cooling (−74 [−125 to −24] W, p = 0.002). Across REC0−60, changes in (−0.38 [−0.69 to −0.07]°C, p = 0.012) and (−1.62 [−2.56 to −0.68]°C, p < 0.0001) were greater with ice vest compared to no cooling. Furthermore, changes in in (−0.39 [−0.70 to −0.08]°C, p = 0.010) and (−1.68 [−2.61 to −0.74]°C, p < 0.0001) were greater with the ice vest compared to single-hand cooling. Using an ice vest during time-limited and prolonged recovery in the heat aided in a more effective reduction in thermo-physiological strain compared to both passive cooling as well as a single-hand cooling device.

Hydration and cooling in elite athletes: relationship with performance, body mass loss and body temperatures during the Doha 2019 IAAF World Athletics Championships

PurposeTo characterise hydration, cooling, body mass loss, and core (Tcore) and skin (Tsk) temperatures during World Athletics Championships in hot-humid conditions.MethodsMarathon and race-walk (20 km and 50 km) athletes (n=83,...

Cooling During Endurance Cycling in the Heat: Blunted Core Temperature but Not Inflammatory Responses.

This study assessed the effects of cooling during endurance cycling (percooling) on changes in core body temperature (Tcore), inflammatory, and metabolic responses. A total of 12 male cyclists (peak oxygen uptake 60 [4]mL·kg-1·min-1) completed a 60-minute constant workload trial (55% of peak power output and ambient temperature 30.4°C [0.6°C]) in a randomized order both with (ICE) and without (CON) an ice vest. An ingestible capsule was used to measure Tcore. Blood samples were collected immediately before and after each trial to determine concentrations of blood lactate, serum cortisol, interleukin-6, and reactive oxygen and nitrogen species. Tcore increased statistically (P < .001) both in CON (7.0% [1.4%], effect size [ES] = 6.3) and ICE (5.1% [1.1%], ES = 5.7). The increase in CON was statistically larger compared with ICE (P = .006, ES = 1.4). Concentrations of blood lactate (CON: 163% [63%], ES = 1.3; ICE: 149% [91%], ES = 1.3), cortisol (CON: 138% [123%], ES = 1.7; ICE: 81% [102%], ES = 1.0), and interleukin-6 (CON: 661% [324%], ES = 2.1; ICE: 624% [368%], ES = 1.2) statistically increased in both conditions (P < .01) to a similar extent. In addition, reactive oxygen and nitrogen species statistically decreased in both conditions (CON: -19.2% [14.9%], P = .002, ES = 0.9; ICE: -15.1% [16.5%], P = .02, ES = 0.9). No correlations were found between the changes of Tcore and blood parameters across the conditions. Despite attenuated Tcore, similar inflammatory and metabolic responses were observed. Our findings suggest percooling to be a promising strategy to attenuate thermal strain without compromising physiological function.

In-play optimal cooling for outdoor match-play tennis in the heat

ABSTRACT The purpose of this study was to compare the efficacy of four cooling interventions used for reducing physiological and perceptual strain and improving exercise performance during outdoor match-play tennis in the heat. Eight competitive tennis players played four counter-balanced simulated outdoor matches in the heat (WBGT: 28.4–32.5°C) at 24- or 48-h intervals. Each match comprised 3 sets for which the “no-ad” rule was applied to limit duration variability. Players underwent the following cooling interventions: ad libitum fluid ingestion (CON), ad libitum fluid ingestion and ice vest (VEST), total ingestion of approximately 1000 g ice slurry and ice vest (Combined: BINE), or total ingestion of approximately 400 g ice slurry and ice vest (Low-combined: L-BINE). Gastrointestinal temperature was lower in the BINE and the L-BINE trials than in the CON trial at the set-break of set 1, and these differences in gastrointestinal temperature persisted throughout the remainder of the match (p < 0.05). The ratio of moderate-high intensity activity (≥10 km/h) in set 3 was significantly higher in the L-BINE trial than that in the BINE trial (p < 0.05). In the CON and BINE trials, high intensity activity was significantly lower in set 3 compared with set 1 and 2, respectively. Cooling by optimal ice slurry ingestion and ice vest may be a more effective strategy in mitigating the development of heat strain during outdoor match-play tennis in the heat. Highlights Cooling by optimal ice slurry ingestion and ice vest may be a more effective strategy in mitigating the development of heat strain during outdoor match-play tennis in the heat. Ingesting of large amounts ice slurry may be caused the bloating and stomach discomfort, in turn declined in the ratio of moderate-high intensity activity in the second half of match-play tennis in hot outdoor environments. Future studies should not only utilize match characteristics, but also measure on-court tennis specific performance.

Effects of Pre-cooling and Per-cooling on Neural, Physiological, and Functional Responses in Active Young Girls

Background: Stressful environments, especially air temperature, have significant effects on human physiological responses to physical activity. Objectives: The current study aimed to determine the effects of pre-cooling and per-cooling on neural, physiological, and functional responses in active young girls. Methods: Twelve active girls (age 24.6 ± 1.4, weight 55.46 ± 8.18, height 165.1 ± 5.91) were tested in three separate sessions with intervals of three days between each session. All subjects performed the Balke test in three groups either without an ice vest (control and pre-cooling) or with an ice vest (per-cooling) in each session, randomly. Pre-cooling was applied with an ice vest for 30 min just before the test, while per-cooling was used with an ice vest from the beginning of the test to exhaustion. A Buerer FT-70 digital thermometer, polar-FT60 heart rate monitoring, Microlife blood pressure monitoring, and ELISA technique were used to measure core body temperature, heart rate, blood pressure, dopamine, cortisol, and lactate dehydrogenase, respectively. Two-way repeated-measures ANOVA was applied to analyze the data with a confidence interval of 95%. Results: The heart rate and core body temperature significantly decreased at the end of the test in the pre-cooling and per-cooling groups (P &lt; 0.05). There was an improved performance with an increase in Tmax in the per-cooling group compared to the control group (P &lt; 0.05) although this difference was not significant in the pre-cooling group compared to the control group (P &gt; 0.05). Dopamine, cortisol, and lactate dehydrogenize increased in the groups in comparison with the pretest (P &lt; 0.05) even though these differences were not significant in the comparison between the groups (P &gt; 0.05). Conclusion: The findings suggest that pre-cooling and per-cooling could be used as a beneficial method to improve performance due to not only a decrease in core body temperature and heart rate but also an increase in the level of dopamine and cortisol. Moreover, per-cooling was more effective than pre-cooling to increase performance.

Comparison of two different cooling systems in alleviating thermal and physiological strain during prolonged exercise in the heat

This study compared the efficacy of an ice vest comprising of water (WATER) or a water-carbon (CARBON) emulsion on thermophysiological responses to strenuous exercise in the heat. Twelve male cyclists completed three 50-minute constant workload trials (55% of peak power output, ambient temperature 30.4 ± 0.6°C) with WATER, CARBON, and without ice vest (CONTROL), respectively. The increase in core body temperature (Tcore) was lower in WATER at 40 (−0.49 ± 0.34 °C) and 50 minutes (−0.48 ± 0.48 °C) and in CARBON at 30 (−0.41 ± 0.48 °C), 40 (−0.54 ± 0.51 °C), and 50 minutes (−0.67 ± 0.62 °C) as compared to CONTROL (p < 0.05, ES > 0.8). While heart rate and blood lactate kinetics did not differ between the conditions, statistical main effects in favour of both WATER and CARBON were found for thermal sensation (condition p < 0.001 and interaction p < 0.01) and rating of perceived exertion (condition p < 0.05). Per-cooling with CARBON and WATER similarly reduced Tcore but not physiological strain during prolonged exercise in the heat. Practitioner Summary: Exercise in the heat is characterised by increases in thermophysiological strain. Both per-cooling with a novel carbon-based and a conventional water-based ice vest were shown to reduce core temperature significantly. However, due to its lower mass, the carbon-based system may be recommended especially for weight-bearing sports.

Health status, heat preparation strategies and medical events among elite cyclists who competed in the heat at the 2016 UCI Road World Cycling Championships in Qatar

PurposeAssess the health status and heat preparation strategies of athletes competing in a World Cycling Championships held in hot ambient conditions (37°C, 25% relative humidity, wet-bulb-globe-temperature 27°C) and monitor the...

Precooling with an ice vest: Effect on core temperature in collegiate female swimmers

Precooling has been shown to improve athletic performance, delay core heating, and decrease heartrate in cyclists and runners, but very little research has observed core temperature (CT), rate of perceived exertion (RPE) and heartrate (HR) response to precooling in collegiate female swimmers. Purpose: The purpose of the current study was to observe the effect of precooling on CT, RPE, and HR while swimming 1600-yards. Methods: Eleven female collegiate swimmers participated in randomized crossover swimming trials with and without precooling. Trials were separated by one week with each subsequent trial performed at the same time of day in the same pool and lane set-up with a water temperature of 26.1° C. Subjects rested for 30 min while wearing an ice vest and wet t-shirt in precooling trials. All trials included the same 15 minute warm up followed by 1600-yards at 75% of their individual fastest mile pace. CT, RPE and HR were recorded before and after warm up, and at 100-yard intervals. Results: Average group precooling CTs were significantly lower (37.88±4° C) than the control condition (38.17±.19° C, P=.02) throughout the test. Group precooling HRs were not significantly different (P=.20), however seven of the 11 subjects did present lower HRs during the precooling trial. Group RPEs were not significantly different between conditions (Pg.05), although six subjects presented significantly higher RPEs in the precooling condition (Pl.05). Conclusion: Precooling using an ice vest 45 min prior to exercise was shown to significantly reduce CT during swimming compared to no precooling. HR and RPE varied between subjects, suggesting that athletes respond differently both physiologically and psychologically to precooling. Coaches should consider individual variation and experiment prior to competition to determine whether precooling can improve performance in a 1600-yd swim.

Limiting the Rise in Core Temperature During a Rugby Sevens Warm-Up With an Ice Vest.

To determine how a cooling vest worn during a warm-up could influence selected performance (countermovement jump [CMJ]), physical (global positioning system [GPS] metrics), and psychophysiological (body temperature and perceptual) variables. In a randomized, crossover design, 12 elite male World Rugby Sevens Series athletes completed an outdoor (wet bulb globe temperature 23-27°C) match-specific externally valid 30-min warm-up wearing a phase-change cooling vest (VEST) and without (CONTROL), on separate occasions 7 d apart. CMJ was assessed before and after the warm-up, with GPS indices and heart rate monitored during the warm-ups, while core temperature (Tc; ingestible telemetric pill; n = 6) was recorded throughout the experimental period. Measures of thermal sensation (TS) and thermal comfort (TC) was obtained pre-warm-up and post-warm-up, with rating of perceived exertion (RPE) taken post-warm-ups. Athletes in VEST had a lower ΔTc (mean [SD]: VEST = 1.3°C [0.1°C]; CONTROL = 2.0°C [0.2°C]) from pre-warm-up to post-warm-up (effect size; ±90% confidence limit: -1.54; ±0.62) and Tc peak (mean [SD]: VEST = 37.8°C [0.3°C]; CONTROL = 38.5°C [0.3°C]) at the end of the warm-up (-1.59; ±0.64) compared with CONTROL. Athletes in VEST demonstrated a decrease in ΔTS (-1.59; ±0.72) and ΔTC (-1.63; ±0.73) pre-warm-up to post-warm-up, with a lower RPE post-warm-up (-1.01; ±0.46) than CONTROL. Changes in CMJ and GPS indices were trivial between conditions (effect size < 0.2). Wearing the vest prior to and during a warm-up can elicit favorable alterations in physiological (Tc) and perceptual (TS, TC, and RPE) warm-up responses, without compromising the utilized warm-up characteristics or physical-performance measures.

The effects of lower body passive heating combined with mixed-method cooling during half-time on second-half intermittent sprint performance in the heat.

This study examined the effects of combined cooling and lower body heat maintenance during half-time on second-half intermittent sprint performances. In a repeated measures design, nine males completed four intermittent cycling trials (32.1 ± 0.3°C and 55.3 ± 3.7% relative humidity), with either one of the following half-time recovery interventions; mixed-method cooling (ice vest, ice slushy and hand cooling; COOL), lower body passive heating (HEAT), combined HEAT and COOL (COMB) and control (CON). Peak and mean power output (PPO and MPO), rectal (Tre), estimated muscle (Tes-Mus) and skin (TSK) temperatures were monitored throughout exercise. During half-time, the decrease in Tre was substantially greater in COOL and COMB compared with CON and HEAT, whereas declines in Tes-Mus within HEAT and COMB were substantially attenuated compared with CON and COOL. The decrease in TSK was most pronounced in COOL compared with CON, HEAT and COMB. During second-half, COMB and HEAT resulted in a larger decrease in PPO and MPO during the initial stages of the second-half when compared to CON. In addition, COOL resulted in an attenuated decrease in PPO and MPO compared to COMB in the latter stages of second-half. The maintenance of Tes-Mus following half-time was detrimental to prolonged intermittent sprint performance in the heat, even when used together with cooling.

An Ice Vest Limits the Rise in Core Temperature During a Rugby Sevens Warm-up

An Ice Vest Limits the Rise in Core Temperature During a Rugby Sevens Warm-up

An Evaluation of Personal Cooling Systems for Reducing Thermal Strain Whilst Working in Chemical/Biological Protective Clothing.

ObjectiveThe use of personal cooling systems to mitigate heat strain on first-responders achieves two potential performance benefits relative to the absence of such cooling: (1) the completion of a workload with less effort; and/or (2) the completion of a greater workload for the same effort. Currently, claims made by manufacturers regarding the capability of their products for use in conjunction with chemical/biological protective clothing remain largely unsubstantiated. The purpose of this investigation was to evaluate the means by which heat strain can be alleviated during uncompensable heat stress in chemical/biological clothing, using the ASTM F2300-10 methodology.MethodsEight healthy males completed five trials of continuous walking (4.5 km h−1; 35°C; 49% RH) for up to 120 min while wearing one of four cooling systems and/or a National Fire and Protection Association 1994 Class-3 chemical/biological ensemble. The four cooling methods (ice vest [IV], phase-change vest [PCM], water-perfused suit [WS], and combination ice slurry/ice vest [SLIV]) and no cooling (CON).ResultsWe observed significant improvements in trial times for IV (18 ± 10 min), PCM (20 ± 10 min) and SLIV (22 ± 10 min), but no differences for WS (4 ± 7 min). Heart rate, rectal, mean skin, and body temperatures were significantly lower in all cooling conditions relative to control at various matched time points in the first 60 min of exercise. Thermal sensation, comfort and perceived exertion all had significant main effects for condition, and time, there were no differences in their respective interactions.ConclusionThe IV, PCM, and SLIV produced lower heart rate, mean skin, rectal and mean body temperatures in addition to improved work times compared to control. The WS did not improve work times possibly as a result of the cooling capacity of the suit abating, and magnifying thermal insulation. Considering the added time and resources required to implement combination cooling in the form of ice slurry and ice vest (SLIV), there was no significant additive effect for perception, cardiovascular strain, rectal temperature and total trial time relative to the phase change vest or ice vest alone. This may be a product of a “ceiling” effect for work limit set to 120 min as part of ASTM F2300-10.

The Threshold Ambient Temperature for the Use of Precooling to Improve Cycling Time-Trial Performance.

Cycling time-trial performance can be compromised by moderate to high ambient temperatures. It has become commonplace to implement precooling prior to competition to alleviate this performance decline. However, little is known about the ambient temperature threshold above which precooling becomes an effective strategy for enhancing endurance performance. The aim of this study was to investigate the effect of precooling in different environmental temperatures on time-trial (TT) performance. Trained cyclists completed 2 TTs with (COLD) and without (CON) precooling using an ensemble of ice vest and sleeves in ambient temperatures of 24°C, 27°C, and 35°C. TT performance was faster following COLD in both 35°C (6.2%) and 27°C (2.6%; both Ps < .05) but not 24°C (1.2%). Magnitude-based inferential statistics indicate that COLD was very likely beneficial to performance in 35°C, likely beneficial in 27°C, and possibly beneficial in 24°C. Mean power was 2.4%, 2.5%, and 5.6% higher following COLD and considered to be likely beneficial in 24°C and very likely beneficial in 27°C and 35°C. COLD reduced mean skin temperature throughout the warm-up and into the TT in all ambient temperatures (P < .05). Sweat loss was lower following COLD in 24°C and 27°C but not 35°C. There was no effect of COLD on gastrointestinal temperature at any point. Precooling with an ice vest and sleeves is likely to have a positive effect on TT performance at temperatures above 24°C, with a clear relationship between ambient temperature and the magnitude of effect of precooling.

Precooling and Warm-Up Effects on Time Trial Cycling During Heat Stress

Heat stress limits endurance exercise performance. Combining precooling and warm-up prior to endurance exercise in the heat may exploit the benefits of both strategies while avoiding the potential negative consequences of each. This study tested the hypothesis that precooling combined with warm-up improves time trial cycling performance in the heat relative to either treatment alone. Nine healthy men completed three 16.1-km time trials in 33°C after: 1) precooling (ice slurry and ice vest) alone (PREC); 2) warm-up alone (WU); or 3) PREC plus WU (COMBO). Tre was lower after PREC compared to WU throughout exercise and lower than COMBO for the first 12 km; COMBO was lower than WU for the first 4 km. Tsk during PREC was lower than COMBO and WU for the first 8 km, and lower in COMBO than WU for the first 4 km. PREC lowered pre-exercise heart rate relative to COMBO and WU (68 ± 10, 106 ± 12, 101 ± 13 bpm, respectively), but it increased similarly during exercise. Local sweat rate (SR) was lower in PREC (0.1 ± 0.1 mg · cm-2 · min-1) than COMBO (0.5 ± 0.2 mg · cm-2 · min-1) and WU (0.6 ± 0.2 mg · cm-2 · min-1) for the first 4 km. Treatments did not differentially affect performance (PREC = 31.9 ± 1.9 min, COMBO = 32.6 ± 2.7 min, WU = 33.1 ± 2.9 min). We conclude precooling alone or with warm-up mitigated thermal strain during exercise, but did not significantly improve 16.1-km cycling time trial performance.Al-horani RA, Wingo JE, Ng J, Bishop P, Richardson M. Precooling and warm-up effects on time trial cycling during heat stress. Aerosp Med Hum Perform. 2018; 89(2):87-93.

Impact of upper body precooling during warm-up on subsequent time trial paced cycling in the heat

ObjectivesThe purpose of this study was to test the hypothesis that cooling the upper body during a warm-up enhances performance during a subsequent 16.1-km simulated cycling time trial in a hot environment. DesignCounterbalanced, repeated measures design. MethodsEight trained, male cyclists (peak oxygen uptake=57.8±5.0mLkg−1min−1) completed two simulated 16.1-km time trials in a hot environment (35.0±0.5°C, 43.8±2.0% relative humidity) each separated by 72h. Treatments were counterbalanced; participants warmed up for 20min while either wearing head and neck ice wraps and an ice vest (COOLING) or no cooling apparatus (CONTROL). ResultsFollowing the warm-up mean skin temperature (T¯sk), mean body temperature (T¯b) and rating of thermal comfort were significantly lower than baseline following the COOLING trial (all P<0.05); however, rectal temperature was unaffected (P=0.35). Because the effects of precooling on T¯sk and T¯b were not sustained during exercise, values for COOLING and CONTROL were not different throughout the time trial (P=0.38). Nonetheless, time to completion was significantly faster following the COOLING intervention when compared to the CONTROL (29.3±3.6min, vs. 30.3±3.1min; P=0.04). ConclusionsThese data suggest that in short distance time trials in hot conditions cyclists may benefit from utilizing a cooling modality during the warm-up.