Lesley W. Vandermark

Tarp-Assisted Cooling as a Method of Whole-Body Cooling in Hyperthermic Individuals

Study objective: We investigated the efficacy of tarp‐assisted cooling as a body cooling modality. Methods: Participants exercised on a motorized treadmill in hot conditions (ambient temperature 39.5°C [103.1°F], SD 3.1°C [5.58°F]; relative humidity 38.1% [SD 6.7%]) until they reached exercise‐induced hyperthermia. After exercise, participants were cooled with either partial immersion using a tarp‐assisted cooling method (water temperature 9.20°C [48.56°F], SD 2.81°C [5.06°F]) or passive cooling in a climatic chamber. Results: There were no differences in exercise duration (mean difference=0.10 minutes; 95% CI –5.98 to 6.17 minutes or end exercise rectal temperature (mean difference=0.10°C [0.18°F]; 95% CI –0.05°C to 0.25°C [–0.09°F to 0.45°F] between tarp‐assisted cooling (48.47 minutes [SD 8.27 minutes]; rectal temperature 39.73°C [103.51°F], SD 0.27°C [0.49°F]) and passive cooling (48.37 minutes [SD 7.10 minutes]; 39.63°C [103.33°F], SD 0.40°C [0.72°F]). Cooling time to rectal temperature 38.25°C (100.85°F) was significantly faster in tarp‐assisted cooling (10.30 minutes [SD 1.33 minutes]) than passive cooling (42.78 [SD 5.87 minutes]). Cooling rates for tarp‐assisted cooling and passive cooling were 0.17°C/min (0.31°F/min), SD 0.07°C/min (0.13°F/min) and 0.04°C/min (0.07°F/min), SD 0.01°C/min (0.02°F/min), respectively (mean difference=0.13°C [0.23°F]; 95% CI 0.09°C to 0.17°C [0.16°F to 0.31°F]. No sex differences were observed in tarp‐assisted cooling rates (men 0.17°C/min [0.31°F/min], SD 0.07°C/min [0.13°F/min]; women 0.16°C/min [0.29°F/min], SD 0.07°C/min [0.13°F/min]; mean difference=0.02°C/min [0.04°F/min]; 95% CI –0.06°C/min to 0.10°C/min [–0.11°F/min to 0.18°F/min]). Women (0.04°C/min [0.07°F/min], SD 0.01°C/min [0.02°F/min]) had greater cooling rates than men (0.03°C/min [0.05°F/min], SD 0.01°C/min [0.02°F/min]) in passive cooling, with negligible clinical effect (mean difference=0.01°C/min [0.02°F/min]; 95% CI 0.001°C/min to 0.024°C/min [0.002°F/min to 0.04°F/min]). Body mass was moderately negatively correlated with the cooling rate in passive cooling (r=–0.580) but not in tarp‐assisted cooling (r=–0.206). Conclusion: In the absence of a stationary cooling method such as cold‐water immersion, tarp‐assisted cooling can serve as an alternative, field‐expedient method to provide on‐site cooling with a satisfactory cooling rate.

Maximizing Athletic Performance in the Heat

ABSTRACT ATHLETES TRAIN AND PERFORM AT OPTIMAL LEVELS IN COOL ENVIRONMENTS; HOWEVER, MANY INDIVIDUALS DO NOT ALTER THEIR TRAINING IN HOT ENVIRONMENTS. THE PURPOSE OF THIS REVIEW IS TO EXPLORE EXISTING RESEARCH RELATED TO ENHANCING PERFORMANCE IN THE HEAT BY MODIFYING THE FOLLOWING PRACTICES: (A) HYDRATION, (B) BODY COOLING, (C) HEAT ACCLIMATIZATION, (D) CLOTHING AND PROTECTIVE EQUIPMENT, (E) NUTRITION AND SUPPLEMENTATION, (F) SLEEP, AND (G) TECHNOLOGY. THIS REVIEW EXPLORES PRACTICAL WAYS ATHLETES CAN CHANGE THEIR EXERCISE HABITS WITH THE GOAL OF INCREASING PERFORMANCE IN HOT ENVIRONMENTS.

Effects of heat acclimation on hand cooling efficacy following exercise in the heat

ABSTRACT This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO2 max], 54.1 ± 1.3 ml·kg−1·min−1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO2 max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90–240 min of treadmill or stationary bike exercise (60–80% VO2 max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min−1) had a greater cooling rate than NC (0.013 ± 0.003°C·min−1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min−1) was similar to NC (0.025 ± 0.002°C·min−1) (0.004°C [−0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min−1) was similar to when NHA (0.020 ± 0.003°C·min−1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.

Athletic Trainer Services in Public and Private Secondary Schools

CONTEXT  The presence of athletic trainers (ATs) in secondary schools to provide medical care is crucial, especially with the rise in sports participation and resulting high volume of injuries. Previous authors have investigated the level of AT services offered, but the differences in medical care offered between the public and private sectors have not been explored. OBJECTIVE  To compare the level of AT services in public and private secondary schools. DESIGN  Concurrent mixed-methods study. SETTING  Public and private secondary schools in the United States. PATIENTS OR OTHER PARTICIPANTS  A total of 10 553 secondary schools responded to the survey (8509 public, 2044 private). MAIN OUTCOME MEASURE(S)  School administrators responded to the survey via telephone or e-mail. Descriptive statistics depict national data. Open-ended questions were evaluated through content analysis. RESULTS  A greater percentage of public secondary schools than private secondary schools hired ATs. Public secondary schools provided a higher percentage of full-time, part-time, and clinic AT services than private secondary schools. Only per diem AT services were more frequent in the private sector. Regardless of the extent of services, reasons for not employing an AT were similar between sectors. Common barriers were budget, school size, and lack of awareness of the role of an AT. Unique to the public sector, remote location was identified as a challenge faced by some administrators. CONCLUSIONS  Both public and private secondary schools lacked ATs, but higher percentages of total AT services and full-time services were available in the public sector. Despite differences in AT services, both settings provided a similar number of student-athletes with access to medical care. Barriers to hiring ATs were comparable between public and private secondary schools; however, remote location was a unique challenge for the public sector.

Coach-led preventive training program in youth soccer players improves movement technique

Long-term implementation of preventive training programs (PTP) in youth sport requires coach involvement. However, the optimal training of coaches to effectively implement a PTP remains unknown. It is also unknown if the benefits of PTP can be enhanced with multiple sport seasons of exposure. OBJECTIVES To evaluate the influence of prior PTP exposure on movement technique in youth soccer players after completing a coach-led PTP. DESIGN Cluster-randomized controlled trial. METHODS Twelve youth soccer teams (n=89; age range 8-14 years) were divided into groups with (Experience (EXP); 6 teams [n=18 females, n=25 males]) and without (Novice (NOV); 6 teams [n=30 females, n=16 males]) previous professional-led PTP experience. The coaches and players of the EXP teams were exposed to an eight-week professional-led PTP before the coach-led PTP. EXP and NOV coaches attended the educational workshop prior to implementing the coach-led PTP. The Landing Error Scoring System (LESS) was used to evaluate movement technique. RESULTS Both groups improved LESS scores over time (mean difference±SD [post-pre]=-0.8±0.2, 95%CI [-1.2, -0.4], p=0.0001). Of the 64 participants classified as high risk for injury (LESS ≥5) prior to PTP implementation, a greater proportion of EXP (n=14) compared to NOV (n=7) participants changed risk classification from high to low (LESSΔ≥1 and LESS <5; p=0.03). CONCLUSIONS Our PTP enhanced movement technique regardless of PTP experience, but the benefits of the PTP impacted a proportionally greater number of players with previous PTP experience supporting continued PTP implementation. Coaches effectively implemented an exercise-based PTP after attending a training workshop regardless of previous PTP experience.

Intermittent exercise-heat exposures and intense physical activity sustain heat acclimation adaptations

OBJECTIVES To determine if intermittent exercise-heat exposures (IHE) every fifth day sustain heat acclimation (HA) adaptations 25 days after initial HA. DESIGN Randomized control trial. METHODS Sixteen non-heat acclimatized men heat acclimated during 10-11 days of exercise in the heat (40°C, 40% RH). A heat stress test (120min, 45% V˙O2peak) before (Pre HA) and after HA (Post HA) in similar hot conditions assessed HA status. Pair-matched participants were randomized into a control group (CON; n=7) that exercised in a temperate environment (24°C, 21%RH) or IHE group (n=9) that exercised in a hot environment (40°C, 40%RH) every fifth day for 25 days following HA (+25d) with out-of-laboratory exercise intensity and duration recorded. Both groups completed +25d in the hot condition. RESULTS Both groups heat acclimated similarly (p>0.05) evidenced by lower heart rate (HR), thermoregulatory, physiological, and perceptual responses (perceived exertion, fatigue, thermal sensation) Pre HA vs. Post HA (p≤0.05). At +25d, post-exercise HR (p=0.01) and physiological strain index (p<0.05) but neither Tre (p=0.18) nor sweat rate (p=0.44) were lower in IHE vs. CON. In IHE only, post-exercise Tre and perceptual responses at Post HA and +25d were lower than Pre HA (p≤0.01). +25d post-exercise epinephrine was higher in CON vs. IHE (p=0.04). Exercise intensity during out-of-lab exercise and +25d post-exercise HR were correlated (r=-0.89, p=0.02) in IHE. CONCLUSIONS Exercise-heat exposures every fifth day for 25 days and regular intense physical activity after HA sustained HR and Tre adaptations and reduced perceptual and physiological strain during exercise-heat stress ∼1 month later.

The Inter-Association Task Force Document on Emergency Health and Safety: Best-Practice Recommendations for Youth Sports Leagues

This document is intended to serve as a call to action for all youth sport NGBs to provide support systems for member organizations through the education of league leaders and their members on the current policy and procedure best practices regarding EAPs, SCA, brain and neck injury, EHS, and other potentially threatening medical conditions (Appendix B). This document also discusses preexisting medical conditions, environmental conditions, and emergency medical care, such as athletic training services. The Task Force recognizes that each organization is unique and, therefore, will need to address policy and procedure recommendations differently to ensure the implementation of best practices. Furthermore, the Task Force recognizes that all best-practice policy and procedure recommendations may not be necessary for each sport (eg, lightning policy for indoor sports). Many of the deaths in youth sports are preventable, and it is the goal of the Task Force to support youth sport NGBs in this mission of prevention.

Beverage Content Influences Voluntary Fluid Intake During Exercise: A Systematic Review: 2034 Board #186 June 2, 2: 00 PM - 3: 30 PM.

Oxidative stress is known to be involved in many adverse mechanisms. Few studies have examined the effects of dehydration on oxidative stress. PURPOSE: Examine the effect of dehydration on plasma oxidative stress and antioxidant capacity in collegiate athletes. METHODS: Eighty-two athletes (56 male, 26 female) were recruited to undergo an acute dehydration (3% body weight), rehydration protocol. Subjects reported to the lab for baseline anthropometrics and blood sampling. The dehydration protocol required subjects to participate in their respective training until 3% of pre-weight body mass was lost. They reported back to the lab where a blood sample was immediately collected. Subjects then drank Gatorade until body weight was reestablished to baseline values. Plasma was collected at 80 min post full re-hydration (PFR) and snap frozen in liquid nitrogen and stored at -80 degrees Celsius until analysis. Oxidative stress was determined by measuring F2-isoprostane lipid oxidation via EIA kit. Ferric reducing ability of plasma (FRAP) was used to measure plasma antioxidant potential. Plasma osmolality was determined by freezing point depression by an osmometer. Statistical analysis consisted of 1-way ANOVA. All values are reported as mean ± SD. RESULTS: Plasma osmolality (280.9 mOsm ± 14.2) significantly elevated (286.2 mOsm ± 15.8) post exercise (p= 0.031), but returned to below normal values (282.1 mOsm ± 15.3) PFR. Plasma FRAP (uM/L ascorbate equivalents) values also increased post dehydration (pre: 0.237 ± 0.068, post: 0.286 ± 0.279), and decreased to near baseline levels PFR (0.247 ± 0.150) but only exhibited a statistical trend (P=0.08). Mean concentrations of F2-isoprostanes (pg/mL) declined from (437.6 ± 125.5) at baseline to (77.5 ± 496) post dehydration, and then rose to (699.73 ± 154.2) PFR (p<0.001). CONCLUSIONS: This study indicates that dehydration causes dramatic increases in plasma osmolality and antioxidant potential. Increased concentrations of antioxidants might be responsible for the reduction in F2-isoprostanes immediately post exercise. This decrease is followed by a large increase at 80 min post full rehydration despite normalization of plasma osmolality. The reasons for the decrease post dehydration and increase after rehydration in F2-isoprostanes warrants further examination.