The Effect of Intermittent Vest Cooling on Thermoregulation and Cardiovascular Strain in Baseball Catchers.

Bishop, SH, Szymanski, DJ, Ryan, GA, Herron, RL, and Bishop, PA. The effect of intermittent vest cooling on thermoregulation and cardiovascular strain in baseball catchers. J Strength Cond Res 31(8): 2060-2065, 2017-Baseball catchers are exposed to multiple physiological challenges while playing outside during the spring and summer months, many of which deal with recovery and thermoregulation. The purpose of this study was to investigate the effect of intermittent cooling on core temperature, cardiovascular strain, exertion, and recovery during a simulated catching performance in the heat. Six trained college-aged baseball catchers performed in a controlled, hot (35° C), and humid (25% relative humidity) environment in a counter-balanced, cross-over design. Ice vest cooling (VC) was used as a cooling modality and was compared with a control of no cooling (NC). Rectal temperature (Tre), heart rate (HR), rating of perceived exertion (RPE), and perceived recovery scale (PRS) were recorded before and after each simulated inning. All activities took place in a heat chamber, and each inning consisted of catchers receiving 12 pitches in their position followed by 6 minutes of recovery. Nine total innings were performed, and 27 total innings were performed with each of the 2 treatments. A significantly smaller mean Tre change was seen in VC when compared with NC (0.58 ± 0.2° C, 0.98 ± 0.2° C, p ≤ 0.01, respectively). Rating of perceived exertion was significantly lower and PRS was significantly improved for VC compared with NC (both p ≤ 0.05). Mean recovery HR during VC was significantly lower than NC in the fifth (VC = 84 ± 8 b·min, NC = 90 ± 9 b·min, p = 0.04), seventh (VC = 84 ± 3 b·min, NC = 92 ± 7 b·min, p = 0.02), and ninth (VC = 85 ± 7 b·min, NC = 93 ± 5 b·min, p = 0.01) innings. Heart rate during catching was significantly lower at the end of the VC trials when compared with NC (108 ± 16 b·min vs. 120 ± 19 b·min, p = 0.02, respectively). Vest cooling decreased heat strain, cardiovascular strain, and RPE while it improved perceived recovery in catchers over a simulated 3-game series performed in hot conditions.

Behind the scenes of JAC: the publisher's role.

In this brief article, we focus on Oxford University Press's role as the publisher of the JAC and how it supports authors and readers. The article defines the role of the publisher, as opposed to the Editorial team, Editorial Office or Society owner. It reviews three key functions at the publisher, namely, editorial, production and marketing.

25(OH)D Status of Elite Athletes with Spinal Cord Injury Relative to Lifestyle Factors.

BACKGROUND: Due to the potential negative impact of low Vitamin D status on performance-related factors and the higher risk of low Vitamin D status in Spinal Cord Injury (SCI) population, research is warranted to determine whether elite athletes with SCI have sufficient 25(OH)D levels. The purposes of this study were to examine: (1) the seasonal proportion of vitamin D insufficiency among elite athletes with SCI; and (2) to determine whether lifestyle factors, SCI lesion level, and muscle performance/function are related to vitamin D status in athletes with SCI. METHODS: Thirty-nine members of the Canadian Wheelchair Sports Association, and the US Olympic Committee Paralympic program from outdoor and indoor sports were recruited for this study. Dietary and lifestyle factors, and serum 25(OH)D concentrations were assessed during the autumn (October) and winter (February/March). An independent t-test was used to assess differences in 25(OH)D status among seasons, and indoor and outdoor sports in the autumn and winter, respectively. RESULTS: Mean ± SD serum 25(OH)D concentration was 69.6 ± 19.7 nmol/L (range from 30 to 107.3 nmol/L) and 67.4 ± 25.5 nmol/L (range from 20 to 117.3 nmol/L)in the autumn and winter, respectively. In the autumn, 15.4% of participants were considered vitamin D deficient (25(OH)D < 50 nmol/L) whereas 51.3% had 25(OH)D concentrations that would be considered insufficient (<80 nmol/L). In the winter, 15.4% were deficient while 41% of all participants were considered vitamin D insufficient. CONCLUSION: A substantial proportion of elite athletes with SCI have insufficient (41%-51%) and deficient (15.4%) 25(OH)D status in the autumn and winter. Furthermore, a seasonal decline in vitamin D status was not observed in the current study.

Effect of carrying a rifle on physiology and biomechanical responses in biathletes.

PURPOSE: This study aimed to assess the effect of carrying a rifle on the physiological and biomechanical responses of well-trained biathletes. METHODS: Ten elite biathletes (five men and five women) performed ski skating with (R) or without a rifle (NR) on a treadmill using the V2 (5° incline) and V1 techniques (8°) at 8 and 6 km·h(-1), respectively, as well as at racing intensity (approximately 95% of peak oxygen uptake (V˙O2peak), 10.7 ± 0.8 and 7.7 ± 0.9 km·h(-1), respectively). V˙O2, ventilation (V˙(E)), HR, blood lactate concentration (BLa), and cycle characteristics as well as pole and leg kinetics were evaluated during these trials. RESULTS: Metabolic data were all higher for R than for NR, as follows: V˙O2, +2.5%; V˙(E), +8.1%; RER, +4.2%; all P < 0.001; HR, +1.7%; and BLa, +15.1%; both P < 0.05. Biomechanically, carrying a rifle reduced cycle time and length, poling and arm swing times, and leg ground contact time and increased cycle rate, the peak and impulse of leg force, average cycle force, and impulse of forefoot force (all P < 0.05). With the exception of elevated pole forces when V2 skating at racing velocity, there were no differences between the peak and impulse of pole force. The difference in V˙(E) between R and NR was greater for the women than that for men (P < 0.05), and the difference in BLa also tended to be larger for the women (P < 0.1). CONCLUSIONS: Carrying a rifle elevated physiological responses, accelerated cycle rate, and involved greater leg work, with no differences between the V1 and V2 techniques.

Anesthesia of tadpoles of the southern brown tree frog (Litoria ewingii) with isoeugenol (Aqui-S).

Because anesthesia of amphibian larvae is currently problematic, the aim of this study was to test if a fish anesthetic containing approximately 500 g/L isoeugenol (Aqui-S) could anesthetize tadpoles. Three concentrations of Aqui-S were tested (of commercial solution 10, 20, and 50 microl/L) with 10 tadpoles of the southern brown tree frog (Litoria ewingii) per concentration. Tadpoles were anesthetized for 15 min in water at 18-20 degrees C. Anesthetic criteria included four time points and two heart rates: time to loss of response to stimulation, loss of righting reflex, and return of spontaneous movement and of righting reflex after removal from Aqui-S, and heart rate after induction and after 15 min of anesthesia. No tadpole showed signs of irritation or excitement, no tadpole died, and all returned to normal behavior. The times for induction of anesthesia (time to loss of righting reflex) decreased significantly (P < 0.001) with increasing concentration: means of 27.5, 16.8, and 5.7 min for 10, 20, and 50 microl/L, respectively. Heart rate after 15 min of anesthesia was significantly lower (P = 0.006) for concentrations of 20 and 50 microl/L compared to 10 microl/L. At the lowest concentration (10 microl/L), anesthesia was light. Recovery times were significantly delayed (P < 0.001) for 50 microl/L, approximately double those for the lower concentrations. Spontaneous movements began at 56.9, 51.4, and 119 min for 10, 20, and 50 microl/L Aqui-S, respectively. Although Aqui-S did anesthetize tadpoles at all three concentrations, with 20 microl/L being the most suitable, additional longer-term toxicity testing is required prior to its adoption as an anesthetic agent for this species. Anesthesia, isoeugenol, Litoria ewingii, southern brown tree frog, tadpoles.

Born to yawn? Understanding yawning as a warning of the rise in cortisol levels: randomized trial.

BACKGROUND: Yawning consistently poses a conundrum to the medical profession and neuroscientists. Despite neurological evidence such as parakinesia brachialis oscitans in stroke patients and thermo-irregulation in multiple sclerosis patients, there is considerable debate over the reasons for yawning with the mechanisms and hormonal pathways still not fully understood. Cortisol is implicated during yawning and may link many neurological disorders. Evidence was found in support of the Thompson cortisol hypothesis that proposes cortisol levels are elevated during yawning just as they tend to rise during stress and fatigue. OBJECTIVES: To investigate whether saliva cortisol levels rise during yawning and, therefore, support the Thompson cortisol hypothesis. METHODS: We exposed 20 male and female volunteers aged between 18 and 53 years to conditions that provoked a yawning response in a randomized controlled trial. Saliva samples were collected at the start and again after the yawning response, or at the end of the stimuli presentations if the participant did not yawn. In addition, we collected electromyographic data of the jaw muscles to determine rest and yawning phases of neural activity. Yawning susceptibility scale, Hospital Anxiety and Depression Scale, General Health Questionnaire, and demographic and health details were also collected from each participant. A comprehensive data set allowed comparison between yawners and nonyawners, as well as between rest and yawning phases. Collecting electromyographic data from the yawning phase is novel, and we hope this will provide new information about neuromuscular activity related to cortisol levels. Exclusion criteria included chronic fatigue, diabetes, fibromyalgia, heart conditions, high blood pressure, hormone replacement therapy, multiple sclerosis, and stroke. We compared data between and within participants. RESULTS: In the yawning group, there was a significant difference between saliva cortisol samples (t10 = -3.071, P = .01). Power and effect size were computed based on repeated-measures t tests for both the yawning and nonyawning groups. There was a medium effect size for the nonyawners group (r = .467) but low power (36%). Results were similar for the yawners group: medium effect size (r = .440) and low power (33%). CONCLUSIONS: There was significant evidence in support of the Thompson cortisol hypothesis that suggests cortisol levels are elevated during yawning. A further longitudinal study is planned to test neurological patients. We intend to devise a diagnostic tool based on changes in cortisol levels that may assist in the early diagnosis of neurological disorders based on the data collected. TRIAL REGISTRATION: International Standard Randomized Controlled Trial Number (ISRCTN): 61942768; http://www.controlled-trials.com/ISRCTN61942768/61942768 (Archived by WebCite at http://www.webcitation.org/6A75ZNYvr).

Half-marathon and full-marathon runners' hydration practices and perceptions.

CONTEXT: The behaviors and beliefs of recreational runners with regard to hydration maintenance are not well elucidated. OBJECTIVE: To examine which beverages runners choose to drink and why, negative performance and health experiences related to dehydration, and methods used to assess hydration status. DESIGN: Cross-sectional study. SETTING: Marathon registration site. PATIENTS OR OTHER PARTICIPANTS: Men (n = 146) and women (n = 130) (age = 38.3 ± 11.3 years) registered for the 2010 Little Rock Half-Marathon or Full Marathon. INTERVENTION(S): A 23-item questionnaire was administered to runners when they picked up their race timing chips. MAIN OUTCOME MEASURE(S): Runners were separated into tertiles (Low, Mod, High) based on z scores derived from training volume, expected performance, and running experience. We used a 100-mm visual analog scale with anchors of 0 (never) and 100 (always). Total sample responses and comparisons between tertile groups for questionnaire items are presented. RESULTS: The High group (58±31) reported greater consumption of sport beverages in exercise environments than the Low (42 ± 35 mm) and Mod (39 ± 32 mm) groups (P < .05) and perceived sport beverages to be superior to water in meeting hydration needs (P < .05) and improving performance during runs greater than 1 hour (P < .05). Seventy percent of runners experienced 1 or more incidents in which they believed dehydration resulted in a major performance decrement, and 45% perceived dehydration to have resulted in adverse health effects. Twenty percent of runners reported monitoring their hydration status. Urine color was the method most often reported (7%), whereas only 2% reported measuring changes in body weight. CONCLUSIONS: Greater attention should be paid to informing runners of valid techniques to monitor hydration status and developing an appropriate individualized hydration strategy.

Effects of metered versus bolus water consumption on urine production and rehydration.

This study compared the effects of a rapid bolus and a slower metered water-consumption rate on urine production and postexercise rehydration. Participants (n = 8) dehydrated by 2% body weight through moderate exercise in an environmentally controlled chamber (35 degrees C, 55% relative humidity). Breakfast and lunch were standardized for all participants during each 8-hr data-collection period. Rehydration was performed using a volume of water equal to that lost during exercise either as bolus consumption (100% of volume consumed in 1 hr; BOL) or metered consumption (12.5% of volume every 30 min for 4 hr; MET). Urine volume was used to assess hydration efficiency (water retained vs. water lost) and net fluid balance at 8 hr. Mean urine outputs were 420 ml (MET) and 700 ml (BOL). A paired-samples t test showed that hydration efficiency was greater for MET (75%) than for BOL (55%; p = .018). These data suggest that metered administration was more effective in maintaining fluid balance. These findings suggest that rehydration rate is a factor in fluid-balance response. For situations in which available fluid volume is restricted, greater hydration efficiency is highly desirable.

Pacing accuracy in collegiate and recreational runners.

To examine runners' ability to produce a prescribed pace, we compared prescribed versus actual 400 m splits for collegiate (COL, n = 12) and recreational runners (REC, n = 16). Participants completed a VO(2max) trial and on a 400 m track, three 3,200 m time trials. During three subsequent sessions, participants completed 800 m warm-up; then, based on their fastest 3,200 m steady pace, subjects completed six laps total at three prescribed paces: (a) 2x 400 m at 7% slower than steady pace (SLO), (b) 2x 400 m at steady pace (AT) and (c) 2x 400 m at 7% faster than steady pace (FAS). Instructions were to complete the sets of two laps in prescribed times (e.g., 75 s per 400 m) (no feedback). Deviation scores (absolute value of difference: prescribed vs. actual time) (s) for each 400 m lap were compared using a 2 (group) x 3 (trial) repeated measures ANOVA. Main effects for deviations among trials SLO (7.3 +/- 6.5), AT (6.6 +/- 6.9) and FAS (6.2 +/- 5.7) were not significantly different (p > 0.05). However, group main effect for deviation scores was significantly (p < 0.05) lower (greater accuracy) for COL (2.9 +/- 3.2 s) versus REC (9.5 +/- 6.6 s). Deviation scores were also significantly different (p < 0.05) for SLO (COL: 3.1 +/- 2.7 s, REC: 10.4 +/- 6.7 s) and AT (COL: 1.9 +/- 1.9 s, REC: 10.1 +/- 7.2 s), with a trend for FAS (p = 0.06) (COL: 3.8 +/- 4.3 s, REC: 7.9 +/- 6.1 s). Bland-Altman plots showed better agreement (prescribed vs. actual) for COL. Experience and fitness of collegiate runners resulted in improved pacing accuracy.

Human physique and sexual attractiveness in men and women: a New Zealand-U.S. comparative study.

Men and women living in New Zealand and California completed five studies regarding human physique and sexual attractiveness. In Studies 1-3, women rated images of male stimuli and, in Studies 4-5, men rated female stimuli. In Study 1, women in both countries rated mesomorphic (muscular) and average male somatotypes as most attractive, followed by ectomorphic (slim) and endomorphic (heavily built) figures. In Study 2, amount and distribution of masculine trunk hair (chest and abdominal) was altered progressively in a series of front-posed male figures. In both countries, the image lacking any trunk hair was rated as the most attractive, with a steady decline in attractiveness as hirsutism became more pronounced. Study 3 assessed attractiveness of front-posed male figures that varied only in the length of the non-erect penis. Five lengths were presented: The smallest penile size was rated as less attractive than three intermediate sizes. The largest penile size was not the most attractive, but received higher scores than the unaltered and smallest penile size. In Study 4, men rated the attractiveness of back-posed female images varying in waist-to-hip ratio (WHR) (from 0.5 to 1.0). The 0.7 WHR figure was rated more attractive in New Zealand and the 0.6 WHR in California. Study 5 measured the attractiveness of female skin color; men expressed preferences for lighter skinned female figures in New Zealand and California. Results indicate very similar preferences for sexually dimorphic physical traits among men and women of European extraction, living in two culturally and geographically different environments.

Cross-sectional area and muscular strength: a brief review.

A brief review is provided on the relationship of strength to muscle cross-sectional area (CSA). It is commonly believed that maximal force and CSA are strongly related. Studies examining varying levels of training status display discordant data suggesting complex relationships between training status, CSA and peak force. It has been reported that trained participants had a significantly larger force to CSA ratio (F/CSA) than untrained males and females. Therefore, it is difficult to attribute all force changes due to training to CSA changes. In general, studies of CSA and strength suggest that sex differences may exist. For example, recreationally trained female weightlifters produced higher F/CSA than males at lower velocities of contraction. Definitive conclusions regarding sex differences, force production and CSA are difficult because of limited studies and equivocal results among these studies. Some studies have also examined the impact of aging on F/CSA. These studies seem to follow the same pattern as studies on sex differences and training status, with data suggesting that F/CSA varies unpredictably across ages and that differences may be attributed to factors other than age alone. In the papers reviewed, the relationship between force and CSA is neither consistent nor simple. Although some of the discrepancies between studies could be attributed to methodological variations, this does not seem likely to explain all differences. The F/CSA relationship seems complex, and future studies are required to elucidate the relationships among key factors in the expression of strength.

WITHDRAWN: Publisher's Note.

The Publisher regrets that this article is an accidental duplication of an article that has already been published in PIAT, 41 (2007) page 371, doi:10.1016/j.jpsychires.2006.11.001. The duplicate article has therefore been withdrawn.

Stability of a practical measure of recovery from resistance training.

McLester et al. (2003) proposed a practical protocol to determine optimal recovery times between resistance training workouts. For this protocol to be useful, it must be stable. The purpose of this study was to investigate the stability of that protocol. College-aged resistance trained men (n = 10) performed 3 sets to volitional failure using a 10-repetition maximum load for 6 exercises. Recovery was evaluated on 4 occasions by the number of repetitions performed for each individual exercise after recovery periods of 48, 72, 96, and 120 hours in counterbalanced order. To evaluate stability, this procedure was performed twice. The number of repetitions after each recovery interval were compared with initial baseline performances. A priori, adequate stability was defined as 70% of the participants achieving similar recovery duration on both trials. Pooled repetitions over all 6 exercises indicated that 80% of participants returned to baseline strength levels after the same recovery duration for both trials. However, when individual muscle group repetition performance was evaluated, stability varied from 20 to 70%. Variability in rest, nutrition, prior activity, and other factors probably induced instability in individual strength measures, but not sufficiently to influence the aggregate results. Some muscle groups may have greater sensitivity to variations in ecological factors such as these. We believe that the tested protocol may be useful in establishing recovery times for multimuscle group workouts, but not stable enough to be useful in establishing recovery times for individual muscle groups.