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Alissa C. Rhode, Lauren M. Lavelle, and David C. Berry

cm deep and include shortwave diathermy (SWD) and therapeutic ultrasound. 2 The physiological effects created by the thermal agent is determined based on the degree of intramuscular temperature increase, duration of temperature increase, size of the area being treated, and rate of temperature rise

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Timothy M. Wohlfert and Kevin C. Miller

Focused Clinical Question Does precooling (PC) with whole-body cold water immersion (CWI) affect thermal sensation (TS) or rating of perceived exertion (RPE) during exercise in the heat? Summary of Search, “Best Evidence” Appraised, and Key Findings • We searched for studies that compared subjects

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Matt B. Brearley and James P. Finn

Background:

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.

Purpose:

To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.

Methods:

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.

Results:

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.

Conclusions:

Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.

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Emiel Schulze, Hein A.M. Daanen, Koen Levels, Julia R. Casadio, Daniel J. Plews, Andrew E. Kilding, Rodney Siegel, and Paul B. Laursen

Purpose:

To determine the effect of thermal state and thermal comfort on cycling performance in the heat.

Methods:

Seven well-trained male triathletes completed 3 performance trials consisting of 60 min cycling at a fixed rating of perceived exertion (14) followed immediately by a 20-km time trial in hot (30°C) and humid (80% relative humidity) conditions. In a randomized order, cyclists either drank ambient-temperature (30°C) fluid ad libitum during exercise (CON), drank ice slurry (−1°C) ad libitum during exercise (ICE), or precooled with iced towels and ice slurry ingestion (15g/kg) before drinking ice slurry ad libitum during exercise (PC+ICE). Power output, rectal temperature, and ratings of thermal comfort were measured.

Results:

Overall mean power output was possibly higher in ICE (+1.4% ± 1.8% [90% confidence limit]; 0.4 > smallest worthwhile change [SWC]) and likely higher PC+ICE (+2.5% ± 1.9%; 1.5 > SWC) than in CON; however, no substantial differences were shown between PC+ICE and ICE (unclear). Time-trial performance was likely enhanced in ICE compared with CON (+2.4% ± 2.7%; 1.4 > SWC) and PC+ICE (+2.9% ± 3.2%; 1.9 > SWC). Differences in mean rectal temperature during exercise were unclear between trials. Ratings of thermal comfort were likely and very likely lower during exercise in ICE and PC+ICE, respectively, than in CON.

Conclusions:

While PC+ICE had a stronger effect on mean power output compared with CON than ICE did, the ICE strategy enhanced late-stage time-trial performance the most. Findings suggest that thermal comfort may be as important as thermal state for maximizing performance in the heat.

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Thomas J. O’Brien, Simon J. Briley, Barry S. Mason, Christof A. Leicht, Keith Tolfrey, and Victoria L. Goosey-Tolfrey

repeated sprint performance and competition. 6 This is due to reduced afferent input to the thermoregulatory center and loss of both sweating capacity and vasomotor control (CON) below the level of lesion. 7 Therefore, WR players with a SCI are at greater risk of thermal strain and thermally induced

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Matt Brearley, Ian Norton, David Kingsbury, and Simon Maas

Introduction:

Anecdotal reports suggest that elite road motorcyclists suffer from high core body temperatures and physiological and perceptual strain when competing in hot conditions.

Methods:

Four male non-heat-acclimatized elite motorcyclists (3 Superbike, 1 Supersport) had their gastrointestinal temperature, heart rate, and respiratory rate measured and recorded throughout practice, qualifying, and race sessions of an Australian Superbike and Supersport Championship round contested in tropical conditions. Physiological strain was calculated during the sessions, and fluid-balance measures were taken during practice and qualifying. Rider thermal sensation was assessed immediately postsession.

Results:

Mean ambient temperature and relative humidity were 29.5–30.2°C and 64.5–68.7%, respectively, across the sessions. Gastrointestinal temperature rose from 37.6°C to 37.7°C presession at a median rate of 0.035°C, 0.037°C ,and 0.067°C/min during practice, qualifying, and race sessions to reach medians of 38.9°C, 38.8°C, and 39.1°C postsession, respectively. The peak postsession gastrointestinal temperature was 39.8°C. Median heart rates were ~164, 160, and 177 beats/min during the respective practice, qualifying, and race sessions, contributing to median physiological strain of 5.5, 5.6, and 6.2 across the sessions. Sweat rates were 1.01 and 0.90 L/h during practice and qualifying sessions, while rider thermal sensation was very hot after each session.

Conclusions:

This investigation confirms that elite road motorcyclists endure moderate to high physiological strain during practice, qualifying, and race sessions, exhibiting more-rapid rates of body-heat storage, higher core body temperatures, and higher physiological and perceptual strain than their stock-car-racing counterparts when competing in tropical conditions.

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Sally A. Perkins and John E. Massie

Objective:

To determine whether patients were satisfied after thermal shrinkage on the capsule of the glenohumeral joint (GHJ).

Design and Setting:

The affected shoulder was assessed preoperatively and 2 months postoperatively. The assessment evaluated pain on activities of daily living (ADLs), physical activity level, satisfaction with shoulder function, and a modified UCLA pain scale.

Subjects:

Eight athletes, 4 men and 4 women, with a mean age of 21 years, participated. Each had sustained a traumatic injury to the GHJ resulting in multidirectional instability.

Measurements:

Subjects were evaluated preoperatively and 2 months postoperatively for GHJ laxity and labral deformity. Goniometric measurements of flexion/extension, abduction/adduction, and internal/external rotation of the GHJ were completed.

Results:

Six of the 8 subjects had reduced pain. Active extension increased significantly in 7. ADLs were all improved. All 8 subjects were satisfied with the thermal-shrinkage procedure.

Conclusions:

Thermal shrinkage of the capsule of the GHJ results in patient satisfaction and reduced pain.

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Kosuke Fujita, Masatoshi Nakamura, Hiroki Umegaki, Takuya Kobayashi, Satoru Nishishita, Hiroki Tanaka, Satoko Ibuki, and Noriaki Ichihashi

The effect of thermal agents on muscle flexibility has been well studied using various methods of heat interventions. 1 – 6 Most of these studies have supported the use of heat intervention for increasing range of motion (ROM). 1 , 2 , 5 , 7 A recent review of research with human participants has

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Michael J. Zurawlew, Jessica A. Mee, and Neil P. Walsh

sweating rate, a reduction in cardiovascular strain, and improved thermal comfort. 2 – 4 Despite practical limitations, heat acclimation recommendations state that individuals should exercise in the heat on 5 to 14 occasions, maintaining a specific degree of hyperthermia (rectal temperature: T re  ≥ 38

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Eric Winters, Steven Doty, and Sean Newell

Objective:

To explore changes in bovine Achilles-tendon elasticity relative to 3 thermal conditions.

Design and Setting:

Posttest-only design with assignment by convenience. Manufactured-apparatus-clamped excised tendon, delivered tensile stress, and provided strain measures. Stress was increased at 1-minute intervals. Strain was observed for each level of stress. Before testing, cold-group tendons were submerged in cold water for 20 minutes. Heat-group tendons were tested in the presence of an ultraviolet lamp. A third group of tendons was tested at room temperature.

Subjects:

Frozen bovine Achilles tendons provided by a meat-rendering factory and segmented into 3 longitudinal strips.

Measurements:

Stress and strain were sequentially measured. Elastic region was identified, elastic-region Young's modulus determined, and elastic limit calculated.

Results:

Young's modulus for cold was 0.956 gigapascal (GPa; ± 0.0621); room temperature, 0.753 GPa (± 0.0624); and heat group, 0.487 GPa (± 0.0407). Significant differences were identified between each of the 3 conditions.

Conclusions:

A direct relationship was observed between imposed thermal energy and tendon elasticity. Thermal energy does not affect the elastic limit.