Precooling Research Articles

Pakcoy Quality Change Study (Brassica rapa L.) in LDPE Packaging (Low Density Polyethylene) With Two Methods Pre Cooling During Cold Storage

Pakcoy vegetables after harvest will change in quality, so it is necessary to handle post-harvest. The pre-cooling method is one of the methods that can be done to prevent these quality changes, the goal is to extend the shelf life of pakcoy. The quality of pakcoy is influenced by environmental conditions during storage. Suitable packaging can prevent the rate of respiration. Respiration can cause a deterioration in the quality of the pakcoy, so before storage it needs to be packaged. This study aims to determine the duration of pakcoy storage packaged with LDPE plastic clips based on changes in weight, moisture content, color, and texture during cold storage in 2 (two) pre-cooling methods, namely room cooling and hydro cooling and comparing the quality of pakcoy carried out pre-cooling with room cooling and hydro cooling methods. This study used experimental methods with pre-cooling treatment, namely room cooling and hydro cooling, data collection was carried out as many as 3 samples per treatment. The data is presented in tables and graphs and then analyzed descriptively. The results showed that pakcoy using the hydro cooling method can be stored for 22 days while using the room cooling method can be stored for 18 days. Pakcoy quality is obtained better in hydro cooling treatment. Keywords: Pakcoy vegetables; post-harvest; respiration; Abstrak Sayuran pakcoy setelah panen akan terjadi perubahan mutu, sehingga perlu adanya penanganan pascapanen. Metode pra pendinginan adalah salah satu metode yang dapat dilakukan untuk mencegah perubahan mutu tersebut, tujuannya adalah memperpanjang masa simpan pakcoy. Mutu pakcoy dipengaruhi oleh kondisi lingkungan selama penyimpanan. Pengemasan yang sesuai dapat mencegah laju respirasi. Respirasi dapat menyebabkan kemunduran mutu pada pakcoy, sehingga sebelum melakukan penyimpanan perlu dikemas. Penelitian ini bertujuan untuk menentukan lama penyimpanan pakcoy yang dikemas dengan plastik klip LDPE berdasarkan perubahan bobot, kadar air, warna dan tekstur selama penyimpanan dingin pada 2 (dua) metode pra pendinginan yaitu room cooling dan hydro cooling serta membandingkan mutu pakcoy yang dilakukan pra pendinginan dengan metode room cooling dan hydro cooling. Penelitian ini menggunakan metode eksperimen dengan perlakuan pra pendinginan yaitu room cooling dan hydro cooling, pengambilan data dilakukan sebanyak 3 sampel setiap perlakuan. Data disajikan dalam tabel dan grafik kemudian dianalisis secara deskriptif. Hasil penelitian menunjukkan bahwa pakcoy menggunakan metode hydro cooling dapat disimpan selama 22 hari sedangkan dengan menggunakan metode room cooling dapat disimpan selama 18 hari. Diperoleh mutu pakcoy lebih baik pada perlakuan hydro cooling. Kata Kunci: Sayuran pakcoy; pascapanen; Respirasi;

Precooling, Hyperthermia, and Postexercise Cooling Rates in Humans Wearing American Football Uniforms.

Exertional heatstroke is one of the leading causes of death in American football players. Precooling (PC) with whole-body cold-water immersion (CWI) may prevent severe hyperthermia and, possibly, exertional heatstroke. However, it is unknown how much PC delays severe hyperthermia when participants wear American football uniforms during exercise in the heat. Does PC alter the effectiveness of CWI once participants become hyperthermic or affect perceptual variables during exercise? We asked 3 questions: (1) Does PC affect how quickly participants become hyperthermic during exercise in the heat? (2) Does PC before exercise affect rectal temperature (Trec) cooling rates once participants become hyperthermic? (3) Does PC affect perceptual variables such as rating of perceived exertion (RPE), thermal sensation, and environmental symptoms questionnaire (ESQ) responses? Crossover study. Laboratory. Twelve physically active males (age = 24 ± 4 years, height = 181.8 ± 8.4 cm, mass = 79.9 ± 10.3 kg). On PC days, participants completed 15 minutes of CWI (9.98°C ± 0.04°C). They donned American football uniforms and exercised in the heat (temperature = 39.1°C ± 0.3°C, relative humidity = 36% ± 2%) until Trec was 39.5°C. While wearing equipment, they then underwent CWI until Trec was 38°C. Control-day procedures were the same except for the PC intervention. Rectal temperature, heart rate, thermal sensation, RPE, and ESQ responses were measured throughout testing. The duration of cold-water immersion was used in conjunction with Trec to calculate cooling rates. Precooling allowed participants to exercise 17.6 ± 3.6 minutes longer before reaching 39.5°C (t11 = 17.0, P < .001). Precooling did not affect postexercise CWI Trec cooling rates (PC = 0.18°C/min ± 0.06°C/min, control = 0.20°C/min ± 0.09°C/min; t11 = 0.9, P = .17); ESQ responses (F2,24 = 1.3, P = .3); or RPE (F2,22 = 2.9, P = .07). Precooling temporarily lowered thermal sensation (F3,26 = 21.7, P < .001) and heart rate (F3,29 = 21.0, P < .001) during exercise. Because PC delayed hyperthermia without negatively affecting perceptual variables or CWI effectiveness, clinicians may consider implementing PC along with other proven strategies for preventing heat illness (eg, acclimatization).

Precooling, Exertional Heatstroke Risk Factors, and Postexercise Cooling Rates.

BACKGROUND: Precooling (PC) before exercise may help prevent severe hyperthermia and exertional heatstroke (EHS). Before clinicians can advocate PC as an EHS prevention strategy, it must effectively mitigate factors associated with EHS development while not lessening the effectiveness of EHS treatment. Therefore, this study determined if PC affected rectal temperature (Trec), body heat storage, heart rate (HR), ratings of perceived exertion (RPE), thermal sensation, sweat rate, and postexercise cold-water immersion (CWI) Trec cooling rates.METHODS: In this randomized, crossover, counterbalanced study, 12 subjects (6 men, 6 women; age = 22 ± 2 yr; mass = 73.5 ± 7.9 kg; height = 171 ± 7 cm) underwent 15 min of CWI (10.0 ± 0.03°C) in an environmental chamber (38.6 ± 0.6°C; 36 ± 2% humidity). After a 10-min rest, they exercised to a Trec of 39.5°C. Subsequently, they underwent CWI (9.99 ± 0.03°C) until Trec reached 38°C. On control (CON) days, the same procedures occurred without the 15-min PC intervention. Trec, HR, thermal sensation, and RPE were measured at various times before, during, and after exercise.RESULTS: PC lowered body heat storage and Trec by 15.7 ± 15.0 W · m-2 and 0.42 ± 0.40°C, respectively, before exercise. Subjects exercised significantly longer (PC = 66.7 ± 16.3 min, CON = 45.7 ± 9.5 min) and at lower Trec (∼0.5 ± 0.5°C) and HR (∼10 ± 7 bpm) following PC. PC significantly lowered sweat rate (PC = 1.02 ± 0.31 L · h-1, CON = 1.22 ± 0.39 L · h-1), but did not affect RPE or CWI cooling rates (PC = 0.18 ± 0.14°C · min-1; CON = 0.19 ± 0.05°C · min-1). Thermal sensation significantly differed between conditions only at pre-exercise (PC = 3 ± 1, CON = 5 ± 0.5).DISCUSSION: PC delayed severe hyperthermia and mitigated dehydration without affecting thermal perception or cooling rates posthyperthermia. PC may help prevent dangerous hyperthermia in athletes.Wohlfert TM, Miller KC. Precooling, exertional heatstroke risk factors, and postexercise cooling rates. Aerosp Med Hum Perform. 2019; 90(1):12-17.

Short-Term Heat Acclimation and Precooling, Independently and Combined, Improve 5-km Time Trial Performance in the Heat.

James, CA, Richardson, AJ, Watt, PW, Willmott, AGB, Gibson, OR, and Maxwell, NS. Short-term heat acclimation and precooling, independently and combined, improve 5-km time trial performance in the heat. J Strength Cond Res 32(5): 1366-1375, 2018-Following heat acclimation (HA), endurance running performance remains impaired in hot vs. temperate conditions. Combining HA with precooling (PC) demonstrates no additive benefit in intermittent sprint, or continuous cycling exercise protocols, during which heat strain may be less severe compared to endurance running. This study investigated the effect of short-term HA (STHA) combined with mixed methods PC, on endurance running performance and directly compared PC and HA. Nine amateur trained runners completed 5-km treadmill time trials (TTs) in the heat (32° C, 60% relative humidity) under 4 conditions; no intervention (CON), PC, short-term HA (5 days-HA) and STHA with PC (HA + PC). Mean (±SD) performance times were; CON 1,476 (173) seconds, PC 1,421 (146) seconds, HA 1,378 (116) seconds and HA + PC 1,373 (121) seconds. This equated to the following improvements versus CON; PC -3.7%, HA -6.6% and HA + PC -7.0%. Statistical differences were only observed between HA and CON (p = 0.004, d = 0.68, 95% CI [-0.27 to 1.63]) however, similar effect sizes were observed for HA + PC vs. CON (d = 0.70, 95% CI [-0.25 to 1.65]), with smaller effects between PC vs. CON (d = 0.34, 95% CI [-0.59 to 1.27]), HA vs. PC (d = 0.33, 95% CI [-0.60 to 1.26]) and HA + PC vs. PC (d = 0.36, 95% CI [-0.57 to 1.29]). Pilot testing revealed a TT typical error of 16 seconds (1.2%). Precooling offered no further benefit to performance in the acclimated individual, despite modest alleviation of physiological strain. Maintenance of running speed in HA + PC, despite reduced physiological strain, may indicate an inappropriate pacing strategy therefore, further familiarization is recommended to optimize a combined strategy. Finally, these data indicate HA, achieved through cycle training, yields a larger ergogenic effect than PC on 5-km running performance in the heat, although PC remains beneficial when HA is not possible.

Does Precooling With Whole-Body Immersion Affect Thermal Sensation or Perceived Exertion? A Critically Appraised Topic.

Clinical Scenario: Exertional heat stroke (EHS) is a potentially deadly heat illness and poses a significant health risk to athletes; EHS survival rates are near 100% if properly recognized and treated. Whole-body cold water immersion (CWI) is the most effective method for lowering body core temperature. Precooling (PC) with CWI before exercise may prevent severe hyperthermia or EHS by increasing the body's overall heat storage capacity. However, PC may also alter athletes' perception of how hot they feel or how hard they are exercising. Consequently, they may be unable to accurately perceive their body core temperature or how hard they are working, which may predispose them to severe hyperthermia or EHS. Clinical Question: Does PC with whole-body CWI affect thermal sensation (TS) or rating of perceived exertion (RPE) during exercise in the heat? Summary of Key Findings: In 4 studies, RPE during exercise ranged from 12 (2.0) to 20 (3.0), with no clinically meaningful differences between PC and control trials. TS scores ranged from 2 (1.0) to 8 (0.5) in control trials and from 2 (1.0) to 7.5 (0.5) during PC trials. Clinical Bottom Line: PC did not cause clinically meaningful differences in RPE or TS during exercise. It is unlikely that PC would predispose athletes to EHS by altering perceptions of exercise intensity or body core temperature. Strength of Recommendation: None of the reviewed studies (all level-2 studies with Physiotherapy Evidence Database scores ≥ 5) suggest that PC with CWI influences RPE or TS in exercising males.

Precooling does not Enhance the Effect on Performance of Midcooling with Ice-Slush/Menthol.

This study investigated whether the combination of internal precooling (PC) and internal midcooling (MC cooling during exercise) would enhance performance more than MC alone. 9 trained males completed two 30-km cycling trials in a hot and humid environment (WBGT: 29±0.7°C, 80±0.02% relative humidity). For 30 min before exercise, the subjects sat quietly and drank water at 23°C (MC) or 3°C (PC+MC). During the MC and PC+MC time trials, they drank an ice-slush/menthol beverage (i. e., 0.025% menthol). Trial time, gastrointestinal temperature (Tco ), heart rate (HR), rating of perceived exertion (RPE), thermal sensation (TS), and thermal comfort (TC) were assessed. Trial time was not significantly different (P>0.05) between MC and PC+MC (3 737±552 s and 3 815±455 s). Before exercise, Tco was lower with precooling (37.0±0.3°C; P<0.02). During exercise, no between-trial differences were noted for Tco, HR, RPE, TC or TS, but RPE was significantly lower with PC+MC in the latter stages (P<0.05). (1) Cold beverage intake before exercise did not improve the subsequent exercise performance with ice-slush/menthol beverage intake, and (2) despite no improvement in performance, RPE declined in the latter stages of exercise in the condition of PC+MC, suggesting that this combination might be beneficial for longer exercise.

Heat‐acclimatization and pre‐cooling: a further boost for endurance performance?

To determine if pre-cooling (PC) following heat-acclimatization (HA) can further improve self-paced endurance performance in the heat, 13 male triathletes performed two 20-km cycling time-trials (TT) at 35°C, 50% relative humidity, before and after an 8-day training camp, each time with (PC) or without (control) ice vest PC. Pacing strategies, physiological and perceptual responses were assessed during each TT. PC and HA induced moderate (+10±18W; effect size [ES] 4.4± 4.6%) and very large (+28±19W; ES 11.7±4.1%) increases in power output (PO), respectively. The overall PC effect became unclear after HA (+4±14W; ES 1.4±3.0%). However, pacing analysis revealed that PC remained transiently beneficial post-HA, i.e., during the first half of the TT. Both HA and PC pre-HA were characterized by an enhanced PO without increased cardio-thermoregulatory or perceptual disturbances, while post-HA PC only improved thermal comfort. PC improved 20-km TT performance in unacclimatized athletes, but an 8-day HA period attenuated the magnitude of this effect. The respective converging physiological responses to HA and PC may explain the blunting of PC effectiveness. However, perceptual benefits from PC can still account for the small alterations to pacing noted post-HA.

Effects of cooling on muscle function and duration of stance phase during gait

Introduction: Cold exposure alters muscular function. Muscle cooling influences the neuromuscular activation during maximal isometric voluntary contractions (MVC) and the amplitude of surface electromyography (sEMG) [1],[2]. It also slows down the mechanical process during contraction [3]. The purpose of this study was to investigate the effects of local cooling in cold water at 10 °C for 20 min in a climate chamber on lower leg muscle activity and gait pattern. Methods: Sixteen healthy adults (eight females), aged Mean (SD) 27.0(2.9) years; body mass 66.3(9.8) kg; and height 169.5(7.8) cm participated in this experimental study. The median frequency (MF) and mean power frequency (MPF) of sEMG from tibialis anterior (TA) and gastrocnemius medialis (GM) muscles during MVC in ankle planter (PF) and dorsi-flexion (DF) against a hand-held dynamometer as well as contact times on a force plate during gait before and after cooling were measured and analysed. Results: The MF and MPF were significantly lower (P<0.01*) in both TA and GM muscle during MVC and in TA during gait trials after cooling. However, the frequency analysis for GM muscle showed no significant difference (P=0.46 and 0.06, respectively) either in MF or MPF during walking on level surface (table 1). Table 1: The means and SD (Hz) for the MF and MPF of the TA and GM during gait and MVC trials before and after cooling (N=16). sEMG Tibialis Anterior (TA) Gastrocnemius Medialis GM Pre Cooling Post Cooling Pre Cooling Post Cooling Gait MF 83.0±10.2* 69.9±9.6* 81.6±12.6 79.3±11.1 Gait MPF 99.7±11.5* 82.3±11.7* 99.8±13.2 93.2±12.4 MVC MF 87.0±9.7* 50.0±6.1* 111.7±16.7* 90.8±14.8* MVC MPF 100.7±10.6* 59.8±7.7* 129.1±15.3* 101.0±16.1* Fig 1: Duration of stance phase in gait trials. Additionally, the post cooling stance phase over the force plate was significantly (P= 0.013) longer than pre-cooling. Discussion: The significant time difference might be caused by the cold induced MF and MPF decrease in sEMG. Our previous investigation reported that cooling increased the sEMG amplitude and produced fatigue like responses in the leg muscles [2]. Moreover, other studies showed that muscle fatigue resulted in electromechanical delay during cold exposure [1], [4]. Conclusion: Moderate degree and duration of cooling may affect muscle motor unit firing rates, thus shifting the sEMG spectrum to lower frequencies, therefore decreasing the leg muscle force production. The result suggests that muscle cooling can cause cold induced frequency decrease in sEMG similar to fatigue response and lead to reduced muscle performance.

Paracetamol (Acetaminophen) Ingestion and Core Body Temperature within Normothermic and Hot Conditions at Rest

Intravenous paracetamol (acetaminophen; ACT) administration results in dose dependent hypothermia (~4°C) within mice. However, the influence of acute oral ACT ingestion on core body temperature (Tc) in humans has not been clearly elucidated in well controlled normothermic (NORM) conditions nor during dry (DRY) and humid (HUMID) heat stress. PURPOSE: The three aims of this study were to i) identify when the peak plasma concentration occurs after acute oral ACT administration, ii) establish any precooling (PC) effect of ACT in NORM conditions and if they correlate with the peak plasma concentration, and iii) investigate if ACT mediated precooling and/or peak plasma concentration alters Tc in DRY and HUMID conditions. METHODS: Fourteen healthy, Caucasian males were randomly allocated to one of two HOT groups; DRY (120 min at 45°C, 30% r.h.) and HUMID (45 min at 45°C, 70% r.h.). Oral ingestion of ACT (20 mg.kg of LBM) was double blinded, and a standardized breakfast (0700) was consumed prior to ACT consumption to control the gastric emptying rate of ACT. All 14 participants completed a NORM (20°C, 30% r.h.) and a HOT (n = 7 in each group) condition. In the NORM condition, the PC effect of ACT was investigated. In the HOT conditions, participants entered the heat chamber when the peak plasma concentration was reached (100 min). Tc was measured every 5 min in all conditions. RESULTS: ACT significantly (p < 0.001) reduced Tc within NORM by ~0.25°C 100 min post ingestion. This precooling effect translated to a decreased mean Tc in DRY and HUMID (p < 0.05), though Tc rate of rise was unchanged. The peak PC effect was significantly correlated with the peak plasma concentration of ACT. CONCLUSION: Oral ACT ingestion elicited a significant PC effect (~0.25°C) effect in NORM, and when ACT was ingested 100 min prior to DRY and HUMID mean Tc was reduced without a change in rate of rise in Tc. Such ACT mediated increases may prove favorable during exercise heat stress.

Precooling does not improve 2,000-m rowing performance of females in hot, humid conditions.

Precooling lowers skin (Tsk) and core temperature (Tre) and can improve performance in hot conditions, but has predominantly been studied in males. This study investigated the effects of precooling on self-paced 2,000-m rowing performance, within females, in hot, humid conditions. Eight physically active females (19.9 ± 1.5 years, 66.8 ± 3.1 kg, 30.0 ± 5.0% body fat) performed 2,000-m rows in a randomized order within 3 conditions {control (CONT) (20° C, 40% relative humidity [RH]); hot (HOT) (35° C, 60% RH); precooling (PREC) (35° C, 60% RH, preceded by precooling)}. The precooling condition consisted of 20-minute precooling with a cold water shower, followed by a 2,000-m row. In contrast, CONT and HOT consisted of 20-minute passive rest in place of precooling. Tre, Tsk, and power output were recorded every 100 m of the rows. Muscle temperature (Tmu) was recorded at baseline, after 20-minute passive rest/precooling and post-row. No differences were observed between conditions for performance time (CONT, 8.89 ± 0.45 minutes; HOT, 9.01 ± 0.55 minutes; PREC, 8.87 ± 0.48 minutes; p = 0.42). Mean Tre during the row was not different between conditions (CONT, 37.8 ± 0.2° C; HOT, 37.7 ± 0.3° C; PREC, 37.5 ± 0.2° C; p = 0.12; main effect), although lower Tre was observed at 1,600 and 1,800 m in PREC compared with HOT (p ≤ 0.05). Tmu was significantly reduced after precooling (p = 0.03). Precooling did not enhance 2,000-m rowing performance, despite differences in Tre, Tsk, and Tmu. The lack of observed improvement in rowing performance after cold shower precooling may have been due to the short exercise time. An improvement in performance may have been observed using an alternate method of precooling, which has been shown to be ergogenic in other sports.

Cooling strategies improve intermittent sprint performance in the heat of athletes with tetraplegia

BackgroundPrecooling has been shown to enhance performance in repeated sprint exercise in able-bodied subjects in a hot environment. Spinal cord injury causes thermoregulatory impairment with a detrimental effect on performance....

Effects of warm-up and precooling on endurance performance in the heat

Objective: To examine the effects of different thermoregulatory preparation procedures (warm-up (WU), precooling (PC), control (C)) on endurance performance in the heat. Methods: 20 male subjects completed three treadmill runs...

Influence Of Whole Body Pre-cooling On Thermoregulation And Motor Skill During Simulated Squash Match Play

Pre-cooling (PC) enables greater endurance capacity during prolonged continuous exercise. Conversely, even though intermittent exercise produces greater thermoregulatory strain, there appears little benefit from PC before prolonged intermittent exercise. Furthermore, there has been no consideration of the impact PC has on motor skill (MS). PURPOSE To examine the influence of whole body PC on thermoregulatory and MS responses during simulated squash match play. METHODS Six male squash players (22 ± 3 yr, 181 ± 5 cm, 75 ± 4 kg) were pre-cooled for 60 min before performing a skill test (ST 1), a 55 min intermittent shuttle protocol designed to simulate squash MP, and a second skill test (ST 2). Core body temperature was measured using an ingested telemetry sensor and mean skin temperature was calculated using a four site method. By replicating shots performed in a match, motor skill was assessed using accuracy of a squash ball hitting pre-determined targets. Comparisons between conditions were performed using a paired t statistic and simple, standardised effect size (ES). RESULTS Pre-cooling lowered both core body temperature (37.3 ± 1.1 °C vs. 38.2 ± 0.7 °C; p=0.001; ES=1.2) and mean skin temperature (30.0 ± 1.8 °C vs. 31.6 ± 1.4 °C; p=0.001; ES=1.2) during simulated match play. Consequently, rate of heat storage was greater after PC (319 ± 75 W·m-2 vs. 226 ± 64 W·m-2; p=0.047; ES=1.5). Pre-cooling impaired motor skill in ST 1, with reduced outer targets hit (15 ± 4 hits vs. 18 ± 3 hits; p=0.056; ES=0.7) and increased errors (16 ± 6 errors vs. 13 ± 5 errors; p=0.048; ES=0.7). Conversely, motor skill in ST 2 was improved after PC with an increased number of inner targets hit (11 ± 3 hits vs. 8 ± 2 hits; p=0.007; ES=1.1). CONCLUSIONS Whole body PC reduces thermoregulatory strain during squash play and is temporally associated with improved MS at the end of simulated squash match play. Supported by University of Bath Studentship.

Influence Of Whole Body Pre-cooling On Thermoregulation And Motor Skill During Simulated Squash Match Play

Pre-cooling (PC) enables greater endurance capacity during prolonged continuous exercise. Conversely, even though intermittent exercise produces greater thermoregulatory strain, there appears little benefit from PC before prolonged intermittent exercise. Furthermore, there has been no consideration of the impact PC has on motor skill (MS). PURPOSE To examine the influence of whole body PC on thermoregulatory and MS responses during simulated squash match play. METHODS Six male squash players (22 ± 3 yr, 181 ± 5 cm, 75 ± 4 kg) were pre-cooled for 60 min before performing a skill test (ST 1), a 55 min intermittent shuttle protocol designed to simulate squash MP, and a second skill test (ST 2). Core body temperature was measured using an ingested telemetry sensor and mean skin temperature was calculated using a four site method. By replicating shots performed in a match, motor skill was assessed using accuracy of a squash ball hitting pre-determined targets. Comparisons between conditions were performed using a paired t statistic and simple, standardised effect size (ES). RESULTS Pre-cooling lowered both core body temperature (37.3 ± 1.1 °C vs. 38.2 ± 0.7 °C; p=0.001; ES=1.2) and mean skin temperature (30.0 ± 1.8 °C vs. 31.6 ± 1.4 °C; p=0.001; ES=1.2) during simulated match play. Consequently, rate of heat storage was greater after PC (319 ± 75 W·m-2 vs. 226 ± 64 W·m-2; p=0.047; ES=1.5). Pre-cooling impaired motor skill in ST 1, with reduced outer targets hit (15 ± 4 hits vs. 18 ± 3 hits; p=0.056; ES=0.7) and increased errors (16 ± 6 errors vs. 13 ± 5 errors; p=0.048; ES=0.7). Conversely, motor skill in ST 2 was improved after PC with an increased number of inner targets hit (11 ± 3 hits vs. 8 ± 2 hits; p=0.007; ES=1.1). CONCLUSIONS Whole body PC reduces thermoregulatory strain during squash play and is temporally associated with improved MS at the end of simulated squash match play. Supported by University of Bath Studentship.

WINGATE SPRINTING PERFORMANCE IN TEMPERATE ENVIRONMENTS FOLLOWING UPPER BODY PRE-COOLING

Hyperthermia is well-established as a limiting factor in exercise performance. Pre-cooling of the body prior to submaximal endurance exercise in the heat has been demonstrated to be effective in improving performance by reducing heat storage, cardiovascular strain, and perception of effort. PURPOSE To investigate the effects of upper-body pre-cooling prior to intermittent sprinting exercise in a temperate environment. METHODS Over two experimental sessions, ten male or female competitive cyclists performed 30 min of cycling exercise at 50% VO2max. At t = 0, 5, 10, 15, 20, 25, and 30 min, they performed a 10 s Wingate cycling sprint with a resistive load of 0.09 kp/kg. In the control (CON) session, subjects rested for 30 min prior to exercise. In the pre-cooling (PC) session, subjects wore the hood and the upper body segment of a liquid cooling garment circulating 5°C coolant for either 75 min or until core temperature decreased by 0.5°C. No warmup occurred during the 5 min transition between the resting/cooling phase and the exercise phase. RESULTS Rectal temperature at the start of exercise was 36.49 ± 0.32°C with PC and 36.97 ± 0.47°C with CON, remaining approximately 0.40°C lower throughout exercise. Skin temperature (unweighted mean of chest, arm, thigh, and calf) at the start of exercise was significantly lower with PC (28.75 ± 2.25°C) than with NC (32.02 ± 1.04°C), but this difference disappeared by 5 min into exercise. Subjective thermal sensation with PC was significantly lower from the start through 10 min of exercise. Heart rate during submaximal exercise were similar between PC and NC, though peak heart rate following the Wingate sprints were lower with PC. With PC, peak power (909 ± 161 W) and mean power output (797 ± 154 W) were similar to CON sprints (peak 921 ± 163 W, mean 806 ± 156 W), with no differences in the subjective ratings of perceived exertion. CONCLUSION Mild upper-body pre-cooling was able to decrease subjective ratings of heat stress, but did not provide any benefit to intermittent sprinting exercise in a temperate environment.

PRE-COOLING REDUCES THERMOREGULATORY STRAIN AND SKIN BLOOD FLOW DURING EXERCISE

1515 It has been suggested that fatigue during exercise in the heat occurs when rectal temperature approaches 39.7°C. Indeed, a number of studies have reported that rectal temperature increases less rapidly following pre-cooling and that as a consequence, time to exhaustion is prolonged. This investigation examined the thermoregulatory effector response (specifically skin blood flow) during exercise with and without prior pre-cooling. Six physically active male subjects cycled intermittental at 65% VO2max in an ambient temperature of 22°C for 45 min on two occassions (control and pre-cooling). The pre-cooling (PC) strategy consisted of shower immersion for a duration of 60 min at a water temperature of 28°C which was subsequently reduced by 2°C every 20 min. Rectal temperature (Tr) was measured 10cm beyond the external anal spincter and sweat production rate (SPR) estimated from nude body mass measurement before and after exercise. Forearm skin blood flow (Skbf) was measured by laser Doppler fluximetry and lactate determined in an arterialised capillary sample. There were no significant differences in baseline heart rate, Tr, Skbf or lactate between trials. However, skin temperatures (Tsk) were significantly reduced as a result of pre-cooling (P<0.05). During exercise, the increase in Tr was significantly greater in the control (0.89±0.11°C) compared with the pre-cooling trial (0.63±0.16°C) (P<0.05). This was associated with a significant reduction in Skbf (57.2±16.1 vs 88.3±21.2PU) and a trend towards reduced weight loss (0.68±0.12 vs 1.40±0.38kg) during the pre-cooling trial. These data indicate that pre-cooling was effective in reducing Skbf and suggest that following pre-cooling central blood volume may be augmented which may reduce any thermoregulatory competition for muscle blood flow.

Vascular surgical society of great britain and ireland: analysis of cold provocation thermography in the objective diagnosis of the hand-arm vibration syndrome

BACKGROUND: The hand-arm vibration syndrome (HAVS) is the commonest prescribed disease in the UK. Presently the diagnosis is subjective and the need for an objective investigation to support the diagnosis has been highlighted. This study analyses the potential of cold provocation thermography (CPT) to fulfil this role. METHODS: CPT was performed in ten controls (five men, five women; median age 35 (range 24-78) years) and 21 patients with HAVS (20 men, one woman; median age 45 (range 29-81) years). With an infrared camera, a precooling (PC) image was taken and then, following hand cooling in water at a temperature of 5 degrees C for 1 min, further rewarming images were taken every minute for 10 min. RESULTS: Patient finger tip temperatures were significantly cooler than control temperatures at all time points (P < 0.01, Student's t test). The following Table shows the sensitivity, specificity and PPV of CPT. CONCLUSION: CPT provides strong objective evidence to support the clinical diagnosis of HAVS.

Performance of Rice Hull Media for Pot Easter Lilies Under Three Forcing Systems1

Abstract Potting media containing parboiled rice hulls as a sand or soil substitute were compared to a soil-sand-peat mix for the production of potted Lilium longiflorum Thunb. cv. Ace under 3 forcing systems: precooling (PC), natural cooling (NC), and controlled temperature forcing (CTF). Plants grown in media containing rice hulls were delayed in flowering (2-3 days) and possessed more flower buds (0.9 buds) independently of forcing system with no effect on stem ht and root dry wt at bloom time. NC and CTF reduced forcing time, and increased stem ht and flower no. over PC. Rice hulls-sand-peat mix increased leaf no. by approx 10 leaves per stem over soil-sand-peat mix under PC or NC but in soil-sand-peat mix, CTF plants had 11 to 15 more leaves per stem than PC and NC plants. Rice hulls in the potting media resulted in lighter wt and improved drainage.