Venous Pooling in Suspension Syndrome Assessed with Ultrasound.

INTRODUCTION: Suspension syndrome describes a potentially life-threatening event during passive suspension on a rope. The pathophysiological mechanism is not fully understood; however, the most widespread hypothesis assumes blood pools in the lower extremities, prompting a reduction in cardiac preload and cardiac output and leading to tissue hypoperfusion, loss of consciousness, and death. The aim of this study was to assess venous pooling by ultrasound in simulated suspension syndrome using human subjects. METHODS: In this trial, 20 healthy volunteers were suspended in a sit harness for a maximum of 60 min with and without preceding exercise. Venous pooling was assessed by measuring the diameter of the superficial femoral vein (SFV) with ultrasound at baseline in supine and standing positions as well as during and after suspension. RESULTS: SFV diameter increased and blood flow became progressively sluggish. In 30% of the tests, near syncope occurred. However, SFV diameter did not differ between subjects with and without near syncope. CONCLUSIONS: Free hanging in a harness leads to rapid venous pooling in the lower limbs. The most important measure to prevent suspension syndrome might be constant movement of the legs.

Aerobic Fitness in Top-Class Soccer Referees.

Castagna, C, Bizzini, M, Araújo Póvoas, SC, Schenk, K, Büsser, G, and D'Ottavio, S. Aerobic fitness in top-class soccer referees. J Strength Cond Res 33(11): 3098-3104, 2019-The aim of this study was to examine the aerobic fitness status of top-class male soccer officials using a cross-sectional design and known population group constructs. Fifty-two field referees (FRs, age 38.4 ± 3.3 years; height 181 ± 5.6 cm; body mass 76.8 ± 6.8 kg; body mass index [BMI] 23.4 ± 1.7 kg·m; body fat 20.4 ± 3.6%; and international refereeing experience 5 ± 3.5 years) and 104 assistant referees (ARs, age 37.8 ± 4.1 years; height 176.9 ± 7.5 cm; body mass 72.1 ± 7.4 kg; BMI 23 ± 1.6 kg·m; body fat 19.2 ± 3.6%; and international refereeing experience 7 ± 3.8 years) from 53 National Football Associations worldwide, and candidates of the preliminary open-list developed by the FIFA Refereeing Department for the 2014 World Cup Final Tournament, were tested for aerobic fitness in laboratory conditions with a progressive speed treadmill test to exhaustion. Large (+8.54%, d = 0.8) and small (+3.1%, d = 0.3) differences in absolute (L·min) and relative (ml·kg·min) VO2max were found between FR and AR, respectively. Trivial differences (d = 0.07) were shown in running economy (RE) (6 minutes at 8 km·h) between AR and FR. Using the scaling notation (b = 0.64), medium and significant differences were found between match officials for VO2max and RE (FR > AR; d = 0.6 and 0.67, respectively). Using receiver operating characteristic curve statistics, cutoff values of 3.93 L·min and 50.6 ml·kg·min were detected in absolute and relative VO2max for the FR and the AR (FR > AR), respectively. The FR showed superior aerobic fitness compared with AR. Training prescription should consider intensities at anaerobic threshold speed (14 km·h, 91% heart rate max) when aerobic fitness development is the aim in elite officials.

[Emergency medicine at the limit: shock-, analgesic therapy and airway management in difficult terrain]. / Notfallmedizin im alpinen Gelände - Schock-, Schmerztherapie und Atemwegssicherung.

Rescue operations in mountain and remote areas pose special challenges for the rescue team and often differ substantially from rescue missions in the urban environment. Given the growing sports and leisure activities in mountains, incidence of alpine emergencies is expected to rise further. The following article describes the treatment of haemorrhagic shock, analgesic therapy and airway management in mountain rescue.

Body fluid status and physical demand during the Giro d'Italia.

The aim of the study was to investigate changes in hydration status by means of bioelectrical impedance vector analyses (BIVA) and to assess its influence on power output and rating of perceived exertion (RPE) during the Giro d'Italia 2014. Daily bioelectrical impedance analysis were performed on 9 professional road cyclists (age: 28.2 ± 4.7 yr, height: 176.0 ± 5.5 cm, weight: 64.7 ± 3.4 kg) during the race. Additionally, body weight, RPE, and power output were recorded throughout the race. Impedance vectors shortened during the race, whereas body weight remained unchanged at the end of the tour when compared to pre-tour. Vector changes were not related to power output or RPE. The shortening of the BIVA vector indicates that fluid gain occurred during the Giro d'Italia. This fluid gain was not reflected by body weight measurements and might be mainly attributed to muscle edema and/or haemodilution. Furthermore, power output and RPE, mostly depending on team tactic, were not affected by the body water increases.

Race performance and exercise intensity of male amateur mountain runners during a multistage mountain marathon competition are not dependent on muscle strength loss or cardiorespiratory fitness.

The aims of this study were to quantify the cardiorespiratory fitness level of amateur mountain runners and to characterize the related cardiorespiratory and muscular strain during a multistage competition. Therefore, 16 male amateur participants performed an incremental treadmill test before the Transalpine-Run 2010. Besides race time, heart rate (HR) was monitored using portable HR monitors during all stages, and countermovement jump ability was assessed after each stage. Overall race time and race times of the single stages were not related to any of the cardiorespiratory fitness parameters assessed during the incremental treadmill test (e.g., V[Combining Dot Above]O2max, ventilatory threshold). Average HR during the first stage was 81 ± 7% of the maximal HR and decreased to 73 ± 6% during the following stages. Creatine kinase activity as an indirect marker of muscle damage and strain amounted to 1,100 ± 619 U·L-1 after the third stage and was related to the decrease in the mean HR between stage 1 and stage 2 (r = -0.616, p < 0.05). Jump ability decreased continuously in the course of the race but was not related to exercise intensity. In conclusion, this study showed that race performance during a multistage mountain marathon does not depend on cardiorespiratory fitness parameters determined in the laboratory. Furthermore, the mean HR decreased after the first stage and remained constant during the following stages independent of the decreased muscle strength. We interpret these data to mean that performance differences were a result of insufficient recovery after the first day of multistage mountain running and the different individual pacing strategies. It is worth mentioning that also other factors, not determined in this investigation, could be responsible for the present outcomes (e.g., nutrition, genetics, psychological and environmental factors, or different training programs).

Ski mountaineering competition: fit for it?

OBJECTIVE: To examine the physiological characteristics of experienced ski mountaineers and to determine the physical demands of ski mountaineering competition. DESIGN: Descriptive field study. SETTING: An international ski mountaineering competition characterized by 20 400 m distance and 1869 m altitude difference that took place in March 2009 in the South Tyrolean Alps (Italy). PARTICIPANTS: Nine healthy and experienced male ski mountaineers. INTERVENTIONS: Bioimpedance measurements for body composition definition; maximal exercise testing (Bruce protocol) to determine maximal heart rate (HRmax), maximal oxygen uptake (.VO2max), and ventilatory thresholds (VT1 and VT2) and to define individual exercise intensity zones; HR registration during competition. MAIN OUTCOME MEASURES: Exercise intensity distribution, occurrence of respiratory symptoms. RESULTS: Ventilatory thresholds were found on average at 70.5% ± 5.0% (VT1) and 90.9% ± 2.6% (VT2) of .VO2max (68.18 ± 6.11 mL·kg⁻¹·minute⁻¹). The overall exercise intensity, defined by the ratio between mean HR during competition and maximal HR in the laboratory (0.87 ± 0.02), was high. Partial times (% of race time) spent competing in 4 defined performance zones were on average 20.4% ± 17.0% (maximal intensity), 59.8% ± 12.5% (high intensity), 12.8% ± 5.6% (moderate intensity), and 7.0% ± 5.9% (low intensity). Five participants reported respiratory discomfort during competition, with cough being the most frequent symptom. Statistical analysis revealed percent body fat mass to correlate with the partial time performed above VT2 (r = 0.782, P < 0.05); the latter was associated with a worse final placement (r = 0.734, P < 0.05). CONCLUSIONS: Competitive ski mountaineering is characterized by an important cardiopulmonary strain and requires a high degree of physical fitness.

Changes in Factors Regulating Serum Sodium Homeostasis During Two Ultra-Endurance Mountain Races of Different Distances: 69km vs. 121km.

Overdrinking and non-osmotic arginine vasopressin release are the main risk factors for exercise-associated hyponatremia (EAH) in ultra-marathon events. However, particularly during ultra-marathon running in mountainous regions, eccentric exercise and hypoxia, which have been shown to modulate inflammation, hormones regulating fluid homeostasis (hypoxia), and oxidative stress, could contribute to serum sodium changes in a dose-dependent manner. To the best of our knowledge, the contribution of these factors, the extent of which depends on the duration and geographical location of the race, has not been well studied. Twelve male participants (11 finishers) of the short (69km, 4,260m elevation-gain) and 15 male participants (seven finishers) of the long (121km, 7,554m elevation-gain) single-stage Südtirol Ultra Sky-Race took part in this observational field study. Venous blood was drawn immediately before and after the race. Analyses included serum sodium concentration, copeptin (a stable marker for vasopressin), markers of inflammation, muscle damage and oxidative stress. Heart rate was measured during the race and race time was obtained from the race office. During the short and the long competition two and one finishers, respectively showed serum sodium concentrations >145mmol/L. During the long competition, one athlete showed serum sodium concentrations <135mmol/L. Only during the short competition percent changes in serum sodium concentrations of the finishers were related to percent changes in body mass (r=-0.812, p=0.002), total time (r=-0.608, p=0.047) and training impulse (TRIMP) (r=-0.653, p=0.030). Data show a curvilinear (quadratic) relationship between percent changes in serum sodium concentration and body mass with race time when including all runners (short, long, finishers and non-finishers). The observed prevalence of hypo- and hypernatremia is comparable to literature reports, as is the relationship between serum sodium changes and race time, race intensity and body mass changes of the finishers of the short race. The curvilinear relationship indicates that there might be a turning point of changes in serum sodium and body mass changes after a race time of approximately 20h. Since the turning point is represented mainly by non-finishers, regardless of race duration slight decrease in body mass and a slight increase in serum sodium concentration should be targeted to complete the race. Drinking to the dictate of thirst seems an adequate approach to achieve this goal.

Hypoxia and hypercapnia effects on cerebral oxygen saturation in avalanche burial: A pilot human experimental study.

BACKGROUND: A sufficient supply of oxygen is crucial to avoid hypoxic cardiac arrest and brain damage within 30 min in completely-buried avalanche victims. Snow density influences levels of hypoxia and hypercapnia. The goal of this study was to investigate the effects of hypoxia and hypercapnia on cerebral oxygenation (ScO2) in humans breathing into an artificial air pocket. METHODS: Each subject breathed into a closed system (air-tight face mask - plastic tube - snow air-pocket of 4 L) up to 30 min. Each subject performed three tests in different snow densities. ScO2 was measured by a near-infrared spectroscopy (NIRS) device. Measurements included peripheral oxygen saturation (SpO2), end-tidal carbon dioxide (ETCO2), air pocket gases and blood gases. Snow density was assessed via standard methods and micro-computed tomography. Based on predetermined criteria, tests were classified based on whether they were terminated before 30 min and the reason for termination. The categories were: completed tests (30 min), tests terminated before 30 min when SpO2 dropped to ≤75% and tests that were terminated before 30 min by requests of the subjects. General linear models were used to compare termination groups for changes in ScO2, ETCO2, SpO2 and air pocket gases, and a multivariate analysis was used to detect factor independent effects on ScO2. RESULTS: ScO2 was decreased in the group in which the tests were terminated for SpO2 ≤ 75% caused by a decrease in oxygen supply in high snow densities. In the completed tests, an increase in ScO2 occurred despite decreased oxygen supply and decreased carbon dioxide removal. CONCLUSIONS: Our data show that ScO2 determined by NIRS was not always impaired in humans breathing into an artificial air pocket despite decreased oxygen supply and decreased carbon dioxide removal. This may indicate that in medium to low snow densities brain oxygenation can be sufficient, which may reflect the initial stage of the triple H (hypothermia, hypoxia, and hypercapnia) syndrome. In high snow densities, ScO2 showed a significant decrease caused by a critical decrease in oxygen supply. This could lead to a higher risk of hypoxic cardiac arrest and brain damage.

Bike Transalp 2008: liquid intake and its effect on the body's fluid homeostasis in the course of a multistage, cross-country, MTB marathon race in the central Alps.

OBJECTIVES: To investigate the drinking behavior of the participants in a multi-day mountain bike (MTB) cross-country competition, to monitor its effect on the body's fluid compartments and body mass, and to evaluate the prevalence of exercise-associated dysnatremia. DESIGN: Descriptive field study. SETTING: The Jeantex Bike Transalp Competition 2008 (8 stages; 665.40 km; 21 691 m height). PARTICIPANTS: Twenty-five male, amateur MTB cyclists. INDEPENDENT VARIABLES: Reported fluid intake during the race, air temperature. MAIN OUTCOME MEASURES: Changes in body mass and body composition from pre to post race and throughout the competition week, serum sodium concentration at finish line of stages 5 and 6. RESULTS: Mean (+ or - SD) hourly fluid intake during the race correlated with air temperature (r = 0.868, P < .05) and ranged between 494 + or - 191 mL/h and 754 + or - 254 mL/h. In absence of exercise-induced hyponatremia (EAH) cases, we report 5 and 4 cases of asymptomatic post-race hypernatremia, on days 5 and 6, respectively. When related to race time and body mass, the liquid intake during the race (in mL x kg(-1) x h(-1)) correlated with post-race serum sodium concentration (stage 5: r = -0.463, P < .05, n = 24; stage 6: r = -0.589, P < .01, n = 23); no correlation was found between the change in body mass from pre to post race and serum sodium concentration at finish line. CONCLUSIONS: Ad libitum fluid consumption during competition was spontaneously adjusted to the unsettled weather conditions in the course of the 2008 "Bike Transalp." The inverse linear relationship between hourly fluid intake and post-race serum sodium concentrations suggests underdrinking to be one contributing factor to the high reported incidence of hypernatremia in the absence of EAH. Experimental studies are requested to confirm this hypothesis and to further examine the pathogenesis of exercise-associated dysnatremia. In this setting, body mass monitoring was not an accurate instrument to control body fluid homeostasis.

Performance Determinants in Short (68 km) and Long (121 km) Mountain Ultra-Marathon Races.

BACKGROUND: Standard performance parameters measured during a laboratory test have been shown to be related to mountain ultra-marathon performance up to a competition length of 75 km. It is not known if a similar relationship exists for longer races. OBJECTIVE: This study aimed to investigate the association between laboratory-based performance parameters and performance times in a short (68 km) and a long (121 km) mountain ultra-marathon. MATERIALS AND METHODS: Eleven male finishers of the short race and seven male finishers of the long race were investigated. Participants performed an incremental exercise test to exhaustion in the 2 weeks prior to the event. During the event, the heart rate was monitored and finishing times were registered. RESULTS: The maximal oxygen consumption and the oxygen uptake at the ventilatory thresholds 1 and 2 were related to performance time during the short run (~12h; r = -0.764 up to r = -0.782; p < 0.05), but there was no correlation during the long race (~28h; r = -0.107 to 0.357; p > 0.05). CONCLUSIONS: This study shows that physical fitness parameters established in a laboratory setting determine competition completion times in ultra-mountain marathon events lasting for ~12 h. During longer races, i. e. ~28 h, other factors not established in the present investigation, such as experience, race strategy, coping with pain and fatigue resistance, may be important for performance.

Effects of snow properties on humans breathing into an artificial air pocket - an experimental field study.

Breathing under snow, e.g. while buried by a snow avalanche, is possible in the presence of an air pocket, but limited in time as hypoxia and hypercapnia rapidly develop. Snow properties influence levels of hypoxia and hypercapnia, but their effects on ventilation and oxygenation in humans are not fully elucidated yet. We report that in healthy subjects breathing into snow with an artificial air pocket, snow density had a direct influence on ventilation, oxygenation and exhaled CO2. We found that a rapid decline in O2 and increase in CO2 were mainly associated with higher snow densities and led to premature interruption due to critical hypoxia (SpO2 ≤ 75%). However, subjects in the low snow density group demonstrated a higher frequency of test interruptions than expected, due to clinical symptoms related to a rapid CO2 accumulation in the air pocket. Snow properties determine the oxygen support by diffusion from the surrounding snow and the clearance of CO2 by diffusion and absorption. Thus, snow properties are co-responsible for survival during avalanche burial.

Bioimpedance identifies body fluid loss after exercise in the heat: a pilot study with body cooling.

PURPOSE: Assessment of post-exercise changes in hydration with bioimpedance (BI) is complicated by physiological adaptations that affect resistance (R) and reactance (Xc) values. This study investigated exercise-induced changes in R and Xc, independently and in bioelectrical impedance vector analysis, when factors such as increased skin temperature and blood flow and surface electrolyte accumulation are eliminated with a cold shower. METHODS: Healthy males (n = 14, 24.1±1.7 yr; height (H): 182.4±5.6 cm, body mass: 72.3±6.3 kg) exercised for 1 hr at a self-rated intensity (15 BORG) in an environmental chamber (33°C and 50% relative humidity), then had a cold shower (15 min). Before the run BI, body mass, hematocrit and Posm were measured. After the shower body mass was measured; BI measurements were performed continuously every 20 minutes until R reached a stable level, then hematocrit and Posm were measured again. RESULTS: Compared to pre-trial measurements body mass decreased after the run and Posm, Hct, R/H and Xc/H increased (p<0.05) with a corresponding lengthening of the impedance vector along the major axis of the tolerance ellipse (p<0.001). Changes in Posm were negatively related to changes in body mass (r = -0.564, p = 0.036) and changes in Xc/H (r = -0.577, p = 0.041). CONCLUSIONS: Present findings showed that after a bout of exercise-induced dehydration followed by cold shower the impedance vector lengthened that indicates fluid loss. Additionally, BI values might be useful to evaluate fluid shifts between compartments as lower intracellular fluid loss (changed Xc/R) indicated greater Posm increase.

Attendance at chlorinated indoor pools and risk of asthma in adult recreational swimmers.

To study a potential correlation between attendance at chlorinated indoor pools and the onset of asthma in adult leisure swimmers. 1136 adult swimmers attending indoor pools in the city of Verona completed a modified ECRHS questionnaire. The cumulative time spent in the pools was calculated on the basis of the mean frequency and duration of weekly swim activity for every year of attendance. The median value (320 h) was used to divide participants into 2 groups. Other questions concerned the family history of allergies, the medical diagnosis and the onset of asthma. The prevalence of respiratory symptoms in the study group was compared with that of a general population sample. New-onset asthma, first identified at least 12 months after the start of regular pool attendance, was more prevalent among swimmers characterized by a higher cumulative pool attendance (23/514, 4.5%) than in swimmers who were attending indoor pools less frequently (2/508, 0.4%; ratio 11.1, 95% CI 2.6-47.4). The statistical analysis revealed an independent association between the cumulative lifetime hours spent in indoor swimming pools and new onset asthma (relative risk 1.05, 95% CI 1.02-1.07). Respiratory symptoms were less frequent in the study population versus a general population sample (prevalence ratio 0.26-0.68). Attendance at chlorinated indoor pools may constitute a risk factor for developing asthma in leisure adult swimmers. Future research and efforts should aim at improving disinfection techniques, hygiene and ventilation in indoor swimming pools in order to provide an unobjectionable ambient for salubrious swim activities.