Energy expenditure of extreme competitive mountaineering skiing

Effect of a four-week isocaloric ketogenic diet on physical performance at very high-altitude: a pilot study

BACKGROUND

A ketogenic diet (KD) reduces daily carbohydrates (CHOs) ingestion by replacing most calories with fat. KD is of increasing interest among athletes because it may increase their maximal oxygen uptake (VO₂max), the principal performance limitation at high-altitudes (1500-3500 m). We examined the tolerance of a 4-week isocaloric KD (ICKD) under simulated hypoxia and the possibility of evaluating ICKD performance benefits with a maximal graded exercise bike test under hypoxia and collected data on the effect of the diet on performance markers and arterial blood gases.

METHODS

In a randomised single-blind cross-over model, 6 recreational mountaineers (age 24-44 years) completed a 4-week ICKD followed or preceded by a 4-week usual mixed Western-style diet (UD). Performance parameters (VO₂max, lactate threshold [LT], peak power [P_peak]) and arterial blood gases (PaO₂, PaCO₂, pH, HCO₃^-) were measured at baseline under two conditions (normoxia and hypoxia) as well as after a 4-week UD and 4-week ICKD under the hypoxic condition.

RESULTS

We analysed data for all 6 participants (BMI 19.9-24.6 kg m^-2). Mean VO₂max in the normoxic condition was 44.6 ml kg^-1 min^-1. Hypoxia led to decreased performance in all participants. With the ICKD diet, median values for PaO₂ decreased by - 14.5% and VO₂max by + 7.3% and P_peak by + 4.7%.

CONCLUSION

All participants except one could complete the ICKD. VO₂max improved with the ICKD under the hypoxia condition. Therefore, an ICKD is an interesting alternative to CHOs dependency for endurance performance at high-altitudes, including high-altitude training and high-altitude races. Nevertheless, decreased PaO₂ with ICKD remains a significant limitation in very-high to extreme altitudes (> 3500 m). Trial registration Clinical trial registration Nr. NCT05603689 (Clinicaltrials.gov). Ethics approval CER-VD, trial Nr. 2020-00427, registered 18.08.2020-prospectively registered.

Ski Mountaineering-Scientific Knowledge of This New Olympic Sport: A Narrative Review

ABSTRACT

Ski mountaineering (skimo) has been accepted as a new sport for the 2026 Milan-Cortina Olympics. The equipment used in this competitive ski mountaineering varies from leisure ski mountaineering equipment mainly in one point: the minimal weight. At the elite athlete level, skimo demands both maximal endurance performance and a high-intensity anaerobic capacity for the sprint and vertical races. Race time significantly correlates to V˙O2max, body mass index and racing gear mass. Available literature only rarely comments on competitive skimo injuries. Injuries are not only due to falls in downhill skiing but also can result from external hazards, such as avalanches and cold. The high training load of athletes in combination with a low body weight, low body fat, and exposure to cold cause high rates of respiratory infections in athletes. The inclusion of skimo into the Olympic program is expected to result in certain changes, such as higher training loads for the athletes and increased scientific interest into training methods.

Heel riser height and slope gradient influence the physiology of ski mountaineering-A laboratory study

In ski mountaineering it is the goal to reach the top of a mountain by sheer muscle force. The specific equipment (flexible boot, only toe fixated binding, and a skin on the ski to prevent from slipping backwards) enables the skier to move up the hill ergonomically, where the heel part of the binding offers a special adaptation possibility. The so-called riser height supports the heel standing height and can be adjusted to individually preferred settings. General recommendations suggest using lower heel support in flat ascents and higher heel support in steep ascents to maintain upright posture and lower the strain. Still, it remains unclear whether the application of riser height affects the physiological response during ski mountaineering. This study was designed to investigate the effects of riser height on physiological response during indoor ski mountaineering. Nineteen participants took part in the study and walked on a treadmill with ski mountaineering equipment. The three available riser heights (low, medium, and high) were applied randomized at 8%, 16%, and 24% gradient. Results show that global physiological measurements like heart rate (p = 0.34), oxygen uptake (p = 0.26) or blood lactate (p = 0.38) values were not affected by changes in riser height. But local measurements of muscle oxygen saturation were affected by the riser height. Additionally comfort and rating of perceived exertion were also prone to changes in riser height. These results suggest differences on local measurements and perceived parameters, while global physiological measurements did not change. The results are in line with the existing recommendations but need to be confirmed in an outdoor setting as well.

Left Ventricular, Left Atrial and Right Ventricular Strain Modifications after Maximal Exercise in Elite Ski-Mountaineering Athletes: A Feasibility Speckle Tracking Study

Eleven world elite ski-mountaineering (Ski-Mo) athletes were evaluated for pronounced echocardiographic physiological remodeling as the primary aim of our feasibility speckle tracking study. In this context, sports-related cardiac remodeling was analyzed by performing two-dimensional echocardiography, including speckle tracking analysis of the left atrium (LA), right ventricle (RV) and left ventricular (LV) global longitudinal strain (LV-GLS) at rest and post-peak performance. The feasibility echocardiographic speckle tracking analysis was performed on eleven elite Ski-Mo athletes, which were obtained in 2022 during the annual medical examination. The obtained data of the professional Ski-Mo athletes (11 athletes, age: 18-26 years) were compared for different echocardiographic parameters at rest and post-exercise. Significant differences were found for LV-GLS mean (p = 0.0036) and phasic LA conduit strain pattern at rest and post-exercise (p = 0.0033). Furthermore, negative correlation between LV mass and LV-GLS (p = 0.0195, r = -0.69) and LV mass Index and LV-GLS (p = 0.0253, r = -0.66) at rest were elucidated. This descriptive reporting provided, for the first time, a sport-specific dynamic remodeling of an entire elite national team of the Ski-Mo athlete's left heart and elucidated differences in the dynamic deformation pattern of the left heart.

Deathly Accidents While High-Altitude Mountaineering in the Swiss Alps-An Observational Analysis from 2009 to 2021

BACKGROUND

High-altitude mountaineering has become more and more popular. While many enjoy the beauty of the highest parts of Switzerland, there are considerable risks, which can even result in death. This study analyzed fatal events while high-altitude mountaineering in the Swiss Alps.

MATERIALS AND METHODS

In this study, cases of emergencies while high-altitude mountaineering in the Swiss Alps were analyzed in the period from 2009 to 2021 from the Swiss Alpine Club (SAC) emergency registry. Fatal emergencies were identified and analyzed in detail.

RESULTS

In total, 5020 emergency cases were analyzed, and among them 303 deathly events where detected. Of the fatal emergencies, 261 cases (86.1%) were male and 42 (13.9%) were female. The average age was 53.2 ± 19.1 years. More than half of the emergencies were on a route to a classic four-thousander. Fatal events were most common on the Matterhorn, with 40 cases (13.2%); on the Mönch, with 18 cases (5.9%); and on the Piz Bernina, with 10 cases (3.3%). In 245 of the fatal emergencies (80.9%), a fall was the cause. The second most prominent cause was rockfalls, with 16 cases (5.3%), followed by stranding, with 10 cases (3.3%), and avalanches, with 9 cases (3%). Illnesses and crevasse accidents counted together for less than 5% of the fatal cases. Almost two-thirds of fatal falls occurred while descending. Concerning nationality, 30% were from Switzerland and more than three-fourths of victims were from the countries of the Alps.

DISCUSSION

We found that falls were the most common cause of fatal emergencies in the Swiss Alps. Concerning the fact that most of these emergencies occurred during descents, fatigue and inadequate focus (forgetting the risks of the descent after successfully reaching the peak) are potential reasons for the fatal events. This potentially resulted from a lack of acclimatization, insufficient physical fitness, and inadequate tour planning. Since most victims were from the countries of the Alps, training tours may be possible as a recommended preparation for more difficult four-thousander peaks.

Heel riser height and slope gradient influence the kinematics and kinetics of ski mountaineering—A laboratory study

In ski mountaineering, equipment and its interaction with the exercising human plays an important role. The binding, as the crucial connection between boot and ski, must ensure safe fixation during downhill skiing and a free moving heel when walking uphill. Uphill, the binding offers the possibility to adopt the height of the heel (riser height) to personal preferences and the steepness of the ascent. This possible adjustment and its influence on various biomechanical parameters are the focus of this work. For this study, 19 male leisure ski mountaineers were tested on a treadmill, ascending at a fixed submaximal speed (3.9 ± 0.4 km·h−1) at 8, 16, and 24% gradient and with three heel riser heights, low (0 cm), medium (3.0 cm) and high (5.3 cm). The applied biomechanical measurement systems included a 3D motion capture system in sagittal plane, pressure insoles, a with strain gauges instrumented pole, spirometry and a comfort scale. Step length and step frequency were influenced by the riser height and the gradient (p ≤ 0.001). The high riser height decreased the step length by 5% compared to the low riser height over all tested gradients, while steps were 9.2% longer at the 24% gradient compared to the 8% gradient over all three riser heights. The high riser height revealed a force impulse of the pole 13% lower than using the low riser height (p < 0.001). Additionally, the high riser height reduced the range of motion of the knee joint and the ankle joint compared to the low riser height (p < 0.001). Therefore, advantageous settings can be derived, with the low riser height creating proper range of motion for ankle, knee and hip joint and higher propulsion via the pole at 8%, while higher riser heights like the medium setting do so at steeper gradients. These findings are in line with the conducted comfort scale. We would not recommend the highest riser height for the analyzed gradients in this study, but it might be an appropriate choice for higher gradients.

Stranded because of exhaustion while high-altitude mountaineering in the Swiss Alps: a retrospective nationwide study

Fortunately, fatal accidents while high-altitude mountaineering have decreased in recent years, but the number of emergencies has increased. These nonfatal emergencies might represent situations where alpinists are stranded (emergencies in which alpinists are no longer able to continue their tour on their own because of, for example, exhaustion, equipment problems, or weather). We analyzed 4596 cases of high-altitude-mountaineering emergencies in the period 2009 to 2020 from the SAC (Swiss Alpine Club) emergency registry. In total, 1951 cases (41.6%) were due to being stranded, 1348 cases were due to falls (28.7%), and 352 cases were due to illness (7.5%); these were the three most common classes. In cases of being stranded, 90% of alpinists were uninjured or not seriously injured. In addition, we found only eight fatal cases. More than 50% of cases occurred while ascending a summit above 4000 m. The main causes of becoming stranded were exhaustion and weather changes. These findings suggest that alpinists contact rescue organizations before experiencing serious troubles; these situations thus present risks and dangers both to those stranded and to emergency services. Since exhaustion and weather changes are the two main causes, adequate preparation and tour planning may help prevent such emergencies.

Exceptional Performance in Competitive Ski Mountaineering: An Inertial Sensor Case Study

Organized biannually in the Swiss Alps since 1984, the “Patrouille des Glaciers” (PDG) is one of the most challenging long-distance ski mountaineering (skimo) team competitions in the world. The race begins in Zermatt (1,616 m) and ends in Verbier (1,520 m), covering a total distance of 53 km with a cumulated 4,386 m of ascent and 4,482 m of descent. About 4,800 athletes take part in this competition, in teams of three. We hereby present the performance analysis of the uphill parts of this race of a member (#1) of the winning team in 2018, setting a new race record at 5 h and 35 min, in comparison with two amateur athletes. The athletes were equipped with the Global Navigation Satellite System (GNSS) antenna, a heart rate monitor, and a dedicated multisensor inertial measurement unit (IMU) attached to a ski, which recorded spatial-temporal gait parameters and transition events. The athletes' GNSS and heart rate data were synchronized with the IMU data. Athlete #1 had a baseline VO₂ max of 80 ml/min/kg, a maximum heart rate of 205 bpm, weighed 69 kg, and had a body mass index (BMI) of 21.3 kg/m². During the race, he carried 6 kg of gear and kept his heart rate constant around 85% of max. Spatiotemporal parameters analysis highlighted his ability to sustain higher power, higher pace, and, thus, higher vertical velocity than the other athletes. He made longer steps by gliding longer at each step and performed less kick turns in a shorter time. He spent only a cumulative 5 min and 30 s during skins on and off transitions. Skimo performance, thus, requires a high aerobic power of which a high fraction can be maintained for a prolonged time. Our results further confirm earlier observations that speed of ascent during endurance skimo competitions is a function of body weight and race gear and vertical energy cost of locomotion, with the latter function of climbing gradient. It is also the first study to provide some reference benchmarks for spatiotemporal parameters of elite and amateur skimo athletes during climbing using real-world data.

Steeper or Faster? Tactical Dispositions to Minimize Oxygen Cost in Ski Mountaineering

Purpose

Investigate the effect of speed, inclination, and use of heel elevator on the oxygen cost of vertical climbing (C_vert) in ski mountaineering.

Methods

In this study, 19 participants who were (3 women and 16 men) moderate- to well-trained recreational Norwegian ski mountaineers were involved. All participants were tested for VO_2max in running, and in a ski mountaineering test on a treadmill, to assess C_vert. The test protocol consisted of 12 4 min work periods at different inclinations from 13 to 23°, with continuous VO₂ measurements. After every second work period, the inclination increased by 2°, and speed was decreased accordingly. The speed reduction was based on the equation V_vert = speed · sin(α), where α represents the angle of inclination. V_vert was thus held constant for each work period (854 m·h⁻¹). All work periods were completed twice, with and without a heel elevator. Half of the subjects started with the smallest inclination, and the other half started with the steepest inclination.

Results

The results showed that C_vert was unchanged at all inclinations except 13°, where there was a significantly higher C_vert, at the same V_vert. Only at 13°, C_vert was higher with the use of heel elevator. There was also a significant trend indicating lower C_vert with use of heel elevator with steeper inclination.

Conclusions

There seemed to be nothing to gain by choosing detours if the inclination was 13° or less. The use of heel elevator was more advantageous, the steeper the inclination, but at 13° there was a negative effect of using heel elevator.

Increased carbohydrate availability effects energy and nutrient periodisation of professional male athletes from the Australian Football League

This research aimed to explore the effect of increased carbohydrate availability intervention on energy intake and distribution in professional Australian Football athletes. Six 24-h energy and macronutrient intakes were quantified (n = 19 males; age 24 ± 4 y, stature 187 ± 8 cm, mass 87 ± 9 kg) using photographic food diaries and Foodworks analyses. Energy expenditure was estimated for the same period using GeneActiv accelerometers. During 3 control days, athletes had ad libitum access to food, while the 3 intervention days increased carbohydrate availability, through greater prompting and access to carbohydrate foods. Daily energy intake was higher during intervention (185 ± 40 kJ/kg/d) compared with control (172 ± 31 kJ/kg/d; p < 0.05) but remained below estimated expenditure, and carbohydrate intake was also greater with intervention (5.0 ± 0.2 g/kg/d) than control (4.0 ± 0.2 g/kg/d; p < 0.05). Expenditure was highest during the morning, which coincided with lowest intake on all days, while the intervention was associated with greater carbohydrate intake in the morning (0.6 g/kg, p < 0.05) compared with control. Increasing availability of carbohydrate during high-load training generated a modest increase in carbohydrate and energy intake, and the intervention was most effective in improving carbohydrate intake during mornings. Novelty: Increased access and provision of carbohydrate foods increased carbohydrate consumption and energy intake on high training load days. Daily distribution of energy intake can be modified through actively promoting carbohydrate consumption.

Ski Mountaineering: Perspectives on a Novel Sport to Be Introduced at the 2026 Winter Olympic Games

Ski mountaineering is a rapidly growing winter sport that involves alternately climbing and descending slopes and various racing formats that differ in length and total vertical gain, as well as their distribution of downhill and uphill sections. In recent years, both participation in and media coverage of this sport have increased dramatically, contributing, at least in part, to its inclusion in the 2026 Winter Olympics in Milano-Cortina. Here, our aim has been to briefly describe the major characteristics of ski mountaineering, its physiological and biomechanical demands, equipment, and training/testing, as well as to provide some future perspectives. Despite its popularity, research on this discipline is scarce, but some general characteristics are already emerging. Pronounced aerobic capacity is an important requirement for success, as demonstrated by positive correlations between racing time and maximal oxygen uptake and oxygen uptake at the second ventilatory threshold. Moreover, due to the considerable mechanical work against gravity on demanding uphill terrain, the combined weight of the athlete and equipment is inversely correlated with performance, prompting the development of both lighter and better equipment in recent decades. In ski mountaineering, velocity uphill is achieved primarily by more frequent (rather than longer) strides due primarily to high resistive forces. The use of wearable technologies, designed specifically for analysis in the field (including at elevated altitudes and cold temperatures) and more extensive collaboration between researchers, industrial actors, and coaches/athletes, could further improve the development of this sport.

Practicing Sport in Cold Environments: Practical Recommendations to Improve Sport Performance and Reduce Negative Health Outcomes

Although not a barrier to perform sport, cold weather environments (low ambient temperature, high wind speeds, and increased precipitation, i.e., rain/water/snow) may influence sport performance. Despite the obvious requirement for practical recommendations and guidelines to better facilitate training and competition in such cold environments, the current scientific evidence-base is lacking. Nonetheless, this review summarizes the current available knowledge specifically related to the physiological impact of cold exposure, in an attempt to provide practitioners and coaches alike with practical recommendations to minimize any potential negative performance effects, mitigate health issues, and best optimize athlete preparation across various sporting disciplines. Herein, the review is split into sections which explore some of the key physiological effects of cold exposure on performance (i.e., endurance exercise capacity and explosive athletic power), potential health issues (short-term and long-term), and what is currently known with regard to best preparation or mitigation strategies considered to negate the potential negative effects of cold on performance. Specific focus is given to "winter" sports that are usually completed in cold environments and practical recommendations for physical preparation.

Assessment of Maximal Aerobic Capacity in Ski Mountaineering: A Laboratory-Based Study

This study aims to evaluate the agreement in maximum oxygen consumption (V˙O₂max) between a running protocol and a ski mountaineering (SKIMO) protocol. Eighteen (eleven males, seven females) ski mountaineers (age: 25 ± 3 years) participated in the study. V˙O₂max, maximum heart rate (HRmax), and maximum blood lactate concentration (BLAmax) were determined in an incremental uphill running test and an incremental SKIMO-equipment-specific test. V˙O₂max did not differ between the SKIMO and uphill running protocols (p = 0.927; mean difference -0.07 ± 3.3 mL/min/kg), nor did HRmax (p = 0.587, mean difference -0.7 ± 5.1 bpm). A significant correlation was found between V˙O₂max SKIMO and V˙O₂max running (p ≤ 0.001; ICC = 0.862 (95% CI: 0.670-0.946)). The coefficient of variation was 4.4% (95% CI: 3.3-6.5). BLAmax was significantly lower for SKIMO compared to running (12.0 ± 14.1%; p = 0.002). This study demonstrates that V˙O₂max determined with a traditional uphill running protocol demonstrates good agreement with an equipment-specific SKIMO protocol.

Physiological Responses and Predictors of Performance in a Simulated Competitive Ski Mountaineering Race

Competitive ski mountaineering (SKIMO) has achieved great popularity within the past years. However, knowledge about the predictors of performance and physiological response to SKIMO racing is limited. Therefore, 21 male SKIMO athletes split into two performance groups (elite: VO_2max 71.2 ± 6.8 ml· min^-1· kg^-1 vs. sub-elite: 62.5 ± 4.7 ml· min^-1· kg^-1) were tested and analysed during a vertical SKIMO race simulation (523 m elevation gain) and in a laboratory SKIMO specific ramp test. In both cases, oxygen consumption (VO₂), heart rate (HR), blood lactate and cycle characteristics were measured. During the race simulation, the elite athletes were approximately 5 min faster compared with the sub-elite (27:15 ± 1:16 min; 32:31 ± 2:13 min; p < 0.001). VO₂ was higher for elite athletes during the race simulation (p = 0.046) and in the laboratory test at ventilatory threshold 2 (p = 0.005) and at maximum VO₂ (p = 0.003). Laboratory maximum power output is displayed as treadmill speed and was higher for elite than sub-elite athletes (7.4 ± 0.3 km h^-1; 6.6 ± 0.3 km h^-1; p < 0.001). Lactate values were higher in the laboratory maximum ramp test than in the race simulation (p < 0.001). Pearson's correlation coefficient between race time and performance parameters was highest for velocity and VO₂ related parameters during the laboratory test (r > 0.6). Elite athletes showed their superiority in the race simulation as well as during the maximum ramp test. While HR analysis revealed a similar strain to both cohorts in both tests, the superiority can be explainable by higher VO₂ and power output. To further push the performance of SKIMO athletes, the development of named factors like power output at maximum and ventilatory threshold 2 seems crucial.

Key Nutritional Considerations for Youth Winter Sports Athletes to Optimize Growth, Maturation and Sporting Development

Despite a wealth of sport nutrition guidelines for adult athletes, there are currently no nutrition guidelines for youth winter sports athletes. Whilst it may be pragmatic to apply nutrition guidelines for adult athletes to youth winter sports athletes, it is inappropriate. Due to a paucity of research on youth athletes, it is impossible to provide evidence-based guidelines for this population, so careful extrapolation from the theoretical and practical considerations that apply to other athletic groups is necessary. Youth winter sport athletes undergo rapid biological growth and maturation which influences their nutritional requirements. A varied and balanced diet that ensures sufficient energy availability for optimal growth and maturation as well as sporting performance is the cornerstone of youth athlete nutrition and should also allow for youth athletes to meet their micronutrient requirements. In some cases, micronutrient status (e.g., vitamin D and iron) should be monitored and optimized if appropriate by a medical professional. Dietary supplement use is prevalent amongst youth athletes, however is often unnecessary. Education of youth athletes, their parents and coaches on best nutritional practices as well as the risks associated with dietary supplements is vital for their long-term athletic development. Further research in youth winter sports athletes across different stages of growth and maturation competing in a variety of sports is urgently required in order to inform nutritional guidelines for this population.

Nutritional Requirements for Sustaining Health and Performance During Exposure to Extreme Environments

Dietary guidelines are formulated to meet minimum nutrient requirements, which prevent deficiencies and maintain health, growth, development, and function. These guidelines can be inadequate and contribute to disrupted homeostasis, lean body mass loss, and deteriorated performance in individuals who are working long, arduous hours with limited access to food in environmentally challenging locations. Environmental extremes can elicit physiological adjustments that alone alter nutrition requirements by upregulating energy expenditure, altering substrate metabolism, and accelerating body water and muscle protein loss. The mechanisms by which the environment, including high-altitude, heat, and cold exposure, alters nutrition requirements have been studied extensively. This contemporary review discusses physiological adjustments to environmental extremes, particularly when those adjustments alter dietary requirements.

Equipment Became Better in Backcountry Skiing-Did Severity of Injuries Decrease? An Analysis from the Swiss Alps

Background: Large technical developments in avalanche transceivers as well as in ski–shoe-binding units should make backcountry skiing a safer sport and as a consequence, yield to a decrease in the number and severity of mountain emergency events. Methods: From 2009–2018, a total of 3044 mountain emergencies (953 females and 2091 males) were identified from the SAC (Swiss Alpine Club) central registry while backcountry skiing. These were classified descriptively by cause, whereby the severity of the mountain emergency was quantified with a NACA-Score (National Advisory Committee for Aeronautics Score). Results: A total of 1357 falls (44.6%), 558 emergencies caused by avalanches (18.3%), 408 cases of blocking (13.4%), 214 cases of illnesses (7.0%), 202 cases of losing way (6.6%), 138 cases of a crevasse accident (4.5%), and material failure in 30 cases (1%) were registered. For the remaining 137 cases (4.5%), no classification or rare forms were detected. No substantial sex differences were found in severity of injury, however looking at the two endpoints of the observed time frame, a significant increase in NACA-Score from 2009 to 2018 (2.1 ± 1.8 up to 2.6 ± 2.1, p < 0.01) was detected. Conclusions: The increase in the severity of mountain emergencies while backcountry skiing in the last decade might be due to the fact that too many inexperienced absolve backcountry tours. The tendency might be promoted by the improved material in the way that it seems easier to absolve a tour while underestimating potential hazards.

[Injuries from Falls in Backcountry Skiing - an Analysis from the Swiss Alps]

Injuries from Falls in Backcountry Skiing - an Analysis from the Swiss Alps Abstract. Ski mountaineering is becoming increasingly popular. In addition to positive aspects, there are also dangers involved whereby falls must be mentioned particularly. Using the central register of the SAC (Swiss Alpine Club), a total of 756 male and 593 female cases of falls in the ten-year period from 2009-2018 were analyzed using the NACA score and case reports. It was found that around 90 % of the analyzed cases in women concerned the lower extremity with the knee (55 %) as the most common localization. Similarly, in men around two thirds were affected by the lower extremity, with the knee being the most common location with around 43 %. This could be caused by an unoptimized binding behavior, which is why it is recommended not to set the bindings too hard and to test the correct release behavior regularly.

Analysis of Daily Energy Expenditure of Elite Athletes in Relation to their Sport, the Measurement Method and Energy Requirement Norms

The purpose of this study was to estimate the daily energy expenditure (DEE) of 30 Polish elite athletes (15 women and 15 men aged 20 to 34 years) representing aerobic-endurance sports and speed-strength sports and to compare the obtained values with energy requirement norms recommended for athletes. Participants' DEE was measured for seven days using a chronometric-tabular method and a kinematic method. The kinematic method provided significantly lower values of DEE, by 25%. Mean DEEs obtained for female aerobic-endurance and speed-strength athletes were 3042.6 ± 389 and 3255.7 ± 359 kcal/24h (a chronometric-tabular method) and 2230.9 ± 209 and 2346.3 ± 355 (the kinematic method), respectively. The differences between the two groups were not statistically significant (p > 0.05). Male athletes' mean DEEs were significantly higher (p < 0.05): 3778.0 ± 657 and 4036.7 ± 532 kcal/24h (a chronometric-tabular method) for aerobic-endurance athletes and 2983.3 ± 545 and 2970.4 ± 345 (the kinematic analysis) for speed-strength athletes. As in the case of female athletes, the differences were not significant (p > 0.05). While no evidence was found that the type of sport alone could cause significant differences in the overall mean DEE between aerobic endurance athletes and speed-strength athletes, athletes' sex significantly differentiated women from men in that respect (the latter's DEE was significantly greater). Such differences were not noted, though, when athletes' relative DEE (adjusted for body mass and body composition) were compared. The study revealed that the actual energy requirements of individual athletes can vary in a wide range and that they can be different from recommended energy intake.

Measuring spatio-temporal parameters of uphill ski-mountaineering with ski-fixed inertial sensors

In this study an algorithm designed for the diagonal stride in classical cross-country skiing was adapted to compute spatio-temporal parameters for uphill ski mountaineering using a ski fixed inertial sensor. Cycle duration, thrust duration, cycle speed, cycle distance, elevation gain, and slope angle were computed and validated against a marker-based motion capture system during indoor treadmill skiing. Skiing movement of 12 experienced, recreational level athletes was measured for nine different speed and slope angle combinations. The accuracy (i.e. mean error) and precision (i.e. standard deviation of the error) were below 3ms and 13ms for the cycle duration and thrust duration, respectively. Accuracy (precision) for cycle speed, cycle distance and elevation gain were -0.013m/s (0.032m/s), -0.027m (0.018m), and 0.006m (0.011m), respectively. Slope angle accuracy and precision were 0.40° and 0.32°, respectively. If the cross-country skiing algorithm would be used without adaptations, errors would be up to one order of magnitude larger. The adapted algorithm proved valid for measuring spatio-temporal parameters for ski-mountaineering on treadmill. It is expected that the algorithm shows similar performance on snow.

Dietary Recommendations for Cyclists during Altitude Training

The concept of altitude or hypoxic training is a common practice in cycling. However, several strategies for training regimens have been proposed, like "live high, train high" (LH-TH), "live high, train low" (LH-TL) or "intermittent hypoxic training" (IHT). Each of them combines the effect of acclimatization and different training protocols that require specific nutrition. An appropriate nutrition strategy and adequate hydration can help athletes achieve their fitness and performance goals in this unfriendly environment. In this review, the physiological stress of altitude exposure and training will be discussed, with specific nutrition recommendations for athletes training under such conditions. However, there is little research about the nutrition demands of athletes who train at moderate altitude. Our review considers energetic demands and body mass or body composition changes due to altitude training, including respiratory and urinary water loss under these conditions. Carbohydrate intake recommendations and hydration status are discussed in detail, while iron storage and metabolism is also considered. Last, but not least the risk of increased oxidative stress under hypoxic conditions and antioxidant supplementation suggestions are presented.

Optimal slopes and speeds in uphill ski mountaineering: a laboratory study

PURPOSE

The purpose of this study was to estimate the energy cost of linear (EC) and vertical displacement (ECvert), mechanical efficiency and main stride parameters during simulated ski mountaineering at different speeds and gradients, to identify an optimal speed and gradient that maximizes performance.

METHODS

12 subjects roller skied on a treadmill at three different inclines (10, 17 and 24 %) at three different speeds (approximately 70, 80 and 85 % of estimated peak heart rate). Energy expenditure was calculated by indirect calorimetry, while biomechanical parameters were measured with an inertial sensor-based system.

RESULTS

At 10 % there was no significant change with speed in EC, ECvert and mechanical efficiency. At 17 and 24 % the fastest speed was significantly more economical. There was a significant effect of gradient on EC, ECvert and mechanical efficiency. The most economical gradient was the steepest one. There was a significant increase of stride frequency with speed. At steep gradients only, relative thrust phase duration decreased significantly, while stride length increased significantly with speed. There was a significant effect of gradient on stride length (decrease with steepness) and relative thrust phase duration (increase with steepness).

CONCLUSION

A combination of a decreased relative thrust phase duration with increased stride length and frequency decreases ECvert. To minimize the energy expenditure to reach the top of a mountain and to optimize performance, ski-mountaineers should choose a steep gradient (~24 %) and, provided they possess sufficient metabolic scope, combine it with a fast speed (~6 km h(-1)).

Nutritional behaviour and beliefs of ski-mountaineers: a semi-quantitative and qualitative study

BACKGROUND

Endurance athletes are advised to optimize nutrition prior to races. Little is known about actual athletes' beliefs, knowledge and nutritional behaviour. We monitored nutritional behaviour of amateur ski-mountaineering athletes during 4 days prior to a major competition to compare it with official recommendations and with the athletes' beliefs.

METHODS

Participants to the two routes of the 'Patrouille des Glaciers' were recruited (A, 26 km, ascent 1881 m, descent 2341 m, max altitude 3160 m; Z, 53 km, ascent 3994 m, descent 4090 m, max altitude 3650 m). Dietary intake diaries of 40 athletes (21 A, 19 Z) were analysed for energy, carbohydrate, fat, protein and liquid; ten were interviewed about their pre-race nutritional beliefs and behaviour.

RESULTS

Despite belief that pre-race carbohydrate, energy and fluid intake should be increased, energy consumption was 2416 ± 696 (mean ± SD) kcal · day(-1), 83 ± 17% of recommended intake, carbohydrate intake was only 46 ± 13% of minimal recommended (10 g · kg(-1) · day(-1)) and fluid intake only 2.7 ± 1.0 l · day(-1).

CONCLUSIONS

Our sample of endurance athletes did not comply with pre-race nutritional recommendations despite elementary knowledge and belief to be compliant. In these athletes a clear and reflective nutritional strategy was lacking. This suggests a potential for improving knowledge and compliance with recommendations. Alternatively, some recommendations may be unrealistic.