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.

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.

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: VO2max 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.

Recovery benefits of using a heat and moisture exchange mask during sprint exercise in cold temperatures.

OBJECTIVES: Breathing cold air can lead to bronchoconstriction and peripheral vasoconstriction, both of which could impact muscular performance by affecting metabolic demands during exercise. Successful solutions dealing with these physiological changes during exercise in the cold has been lacking; therefore, we investigated the influence of a heat and moisture exchange mask during exercise in the cold. METHODS: There were three trial arms within this study: wearing the heat and moisture exchange mask during the rest periods in the cold, no-mask application during the rest periods in the cold, and a trial at room temperature (22°C). Eight subjects cycled in four 35 kJ sprint sessions with each session separated by 20 min rest period. Workload was 4% of body mass. RESULTS: Mean sprint times were faster with heat and moisture exchange mask and room temperature trial than cold, no-mask trial (133.8 ± 8.6, 134.9 ± 8.8, and 138.0 ± 8.4 s (p = 0.001)). Systolic blood pressure and mean arterial pressure were greater during the cold trial with no mask (15% and 13%, respectively), and heart rate was 10 bpm less during the third rest or recovery period during cold, no mask compared to the heat and moisture exchange mask and room temperature trials. Subjects demonstrated significant decreases in vital capacity and peak expiratory flow rate during the cold with no mask applied during the rest periods. CONCLUSIONS: These negative responses to cold exposure were alleviated by the use of a heat and moisture exchange mask worn during the rest intervals by minimizing cold-induced temperature stress on the respiratory system with subsequent maintenance of cardiovascular function.

The influence of D-ribose ingestion and fitness level on performance and recovery.

BACKGROUND: Skeletal muscle adenosine triphosphate (ATP) levels are severely depleted during and following prolonged high intensity exercise. Recovery from these lower ATP levels can take days, which can affect performance on subsequent days of exercise. Untrained individuals often suffer the stress and consequences of acute, repeated bouts of exercise by not having the ability to perform or recovery sufficiently to exercise on subsequent days. Conversely, trained individuals may be able to recover more quickly due to their enhanced metabolic systems. D-Ribose (DR) has been shown to enhance the recovery in ATP; however, it is not known if recovery and performance can be benefitted with DR ingestion. Therefore, this study was designed to determine what influence DR might have on muscular performance, recovery, and metabolism during and following a multi-day exercise regimen. METHODS: The study was a double blind, crossover study in 26 healthy subjects compared 10 g/day of DR to 10 g/day of dextrose (DEX, control). All subjects completed 2 days of loading with either DR or DEX, followed by 3 additional days of supplementation and during these 3 days of supplementation, each subject underwent 60 min of high intensity interval exercise in separate daily sessions, which involved cycling (8 min of exercise at 60% and 2 min at 80% VO2max), followed by a 2 min power output (PO) test. Subjects were divided into two groups based on peak VO2 results, lower VO2 (LVO2) and higher peak VO2 (HVO2). RESULTS: Mean and peak PO increased significantly from day 1 to day 3 for the DR trial compared to DEX in the LVO2 group. Rate of perceived exertion (RPE) and creatine kinase (CK) were significantly lower for DR than DEX in the LVO2 group. No differences in PO, RPE, heart rate, CK, blood urea nitrogen, or glucose were found between either supplement for the HVO2 group. CONCLUSION: DR supplementation in the lower VO2 max group resulted in maintenance in exercise performance, as well as lower levels of RPE and CK. Unlike no observed benefits with DEX supplementation.

Grade and speed have greater influence on HR and RPE than ability, sex, and age in alpine skiing.

The purpose of this study was to investigate the influence of ski slope grade, skiing speed, skiing ability, sex, and age on HR, RPE, and energy expenditure responses during recreational alpine skiing. Thirty-eight participants were divided by age, sex, and skiing ability. Instructor- and self-paced skiing conditions were conducted on 10° and 19.8° slopes. Skiing HR was recorded, RPE collected at the end of each run, and energy expenditure calculated. The pertinent results of this study demonstrate that the interactions of grade × speed, speed × age, and grade × age and the main effects of speed and grade significantly influenced %HRmax, mean HR, RPE, and energy expenditure during skiing. When %HRmax is taken into account, the older skiers skied at a greater relative intensity than the young skiers. The sex, age, and skiing ability main effects did not have a significant influence on mean HR, RPE, and energy expenditure. These data demonstrates that increased speed and grade results in increased physiological stress. Using mean, HR data may not be the best option for assessing physiological stress during exercise in the older athlete as it does not account for the influence of the ageing process.

The influence of commercial energy shots on response time and power output in recreational cyclists.

BACKGROUND: Caffeine based energy shot products accounted for $1.3 billion in sales in 2011. Caffeine has been shown to confer numerous benefits during exercise and is oftentimes combined with ingredients such as carbohydrates and taurine in the hope of further performance improvement. The purpose of this project was to compare auditory response time, power output, and physiological responses between the ingestion of a CHO, PRO, caffeine supplement (CPC), a caffeine-taurine-niacin based supplement (CTN), and a placebo (PL) in commercially formulated products that make claims as to improving performance. METHODS: Fourteen subjects cycled an interval exercise of 70% VO2max for 13 minutes and 90% of VO2max for two minutes for a total of 120 minutes which was then followed by a six-minute power output (PO) task. Subjects ingested a total of 45 g CHO, 7.5 g PRO, and 375 mg caffeine for CPC while 512 mg caffeine and 1200 mg taurine were ingested for CTN throughout the exercise. The treatments were administered in a double blind, randomly assigned protocol. Response time was assessed by auditory response. Significance was set at p < 0.05. RESULTS: Average PO was significantly greater for CPC: 309 ± 60 W than CTN: 290 ± 57 W and PL: 282 ± 63 W. Response time was significantly faster for the CPC: 0.219 ± .049 s than CTN: 0.232 ± .060 s and PL: 0.228 ± .047 s. HR was significantly greater for CTN: 143 ± 16 bpm than CPC: 139 ± 16 bpm. RPE was significantly lower for CPC: 13.0 ± 1.7 than CTN: 13.5 ± 1.2 and PL: 13.8 ± 1.9. Blood glucose was greater for CPC: 5.5 ± 0.8 mM/L than CTN: 4.9 ± 0.7 mM/L and PL: 4.6 ± 1.1 mM/L. No significant differences were observed for RER. CONCLUSIONS: The co-ingestion of CPC improved both cycling power output and auditory response time following 2 hours of moderate and high intensity interval cycling compared to CTN and PL. It is possible that the CPC treatment conferred not only a positive peripheral effect, but also a central effect. Even with a large caffeine dose, the combination of caffeine, taurine, niacin led to an inhibitory pattern which did not improve power output or response time performances over a PL.

A heat and moisture mask attenuates cardiovascular stress during cold air exposure.

BACKGROUND: Exposure to cold has been shown to cause cardiovascular stress and increased morbidity and mortality. Inhalation of cold, dry air can increase blood pressure and induce myocardial ischemia, particularly in people with preexisting hypertensive cardiovascular disease. Face masks that can warm and humidify inhaled cold air may reduce these cold air pressor effects. METHOD: We compared blood pressure measurements using a heat and moisture exchange mask (HME), a placebo mask (PL), and no mask (NM) in 53 patients with hypertension exposed to a cold chamber environment at -5°C for 1 h. Blood pressure and heart rate were recorded at baseline, and at 15 min intervals from 0 to 60 min of chamber exposure. All patients were taking antihypertensive medications with drug and dosage determined by their own physicians. Data were analyzed by a one-way analysis of variance test with repeated measures, and significant interactions were analyzed by Fisher's least significant differences tests. A post hoc subgroup analysis for the effect of age was performed using Wilcoxon matched-pair rank tests. RESULTS: Wearing the HME resulted in significantly lower systolic and mean arterial blood pressures than the PL and NM conditions. Diastolic blood pressures were significantly lower for the HME than the NM, but not the PL condition. CONCLUSION: Subgroup analyses suggested that the effect of the HME in mitigating systolic blood pressure increase from inhalation of cold air was significantly greater for patients aged 60 years or over than for those under 60 years.

The effects of a carbohydrate-protein gel supplement on alpine slalom ski performance.

Alpine slalom ski racing is a high intensity, complex sport in which racers execute turns every second. Acute fatigue can make the difference in not finishing a run (DNF) or finishing out of contention. The quantity and quality of training often dictates racing success. It is not known if nutritional supplementation can improve performance in this high intensity, short duration activity. The objective of this study was to determine if ingesting a carbohydrate-protein energy gel (GEL) improves finishing success and number of gates completed during 2 hr slalom sessions on two consecutive days of training. Twenty-four racers were matched; one group ingested the GEL, the second group received a liquid placebo (PLA). Total carbohy-drate, protein, and water ingested by the GEL group were 60g, 15g, and 450 mL, while the PLA group ingested 450 mL of PLA. The GEL group had significantly fewer DNF's (7/48 vs. 18/48; p = 0.02) on both days, completed a greater number of training gates on Day 2 (260.3 ± 20.1 vs. 246.3 ± 17.5 gates; p = 0.03), and had a lower RPE (3.9 ± 1.2 vs. 5.3 ± 1.2 on Day 2 (p = 0.004) vs. PLA. The statistical analysis of combined finishing times was not possible due to the high number of DNF's in the PLA group. High intensity slalom performance can be im-proved by the ingestion of an energy gel. The GEL allowed the athletes to improve training quantity and quality and their per-ception of effort was less than skiers who ingested a placebo. Key pointsNutritional supplementation with a carbohydrate/protein sports gel during high intensity ski training improved training volume as measured by the number gates completed.Supplementation also reduced the number of DNF's during training.Racers' perception of effort was significantly lower with the supplement ingestion compared to a non-caloric placebo.This applied study was conducted under real life field conditions and training environments.

Effect of acute administration of an herbal preparation on blood pressure and heart rate in humans.

Confusion and controversy exist regarding the cardiovascular effects of dietary supplements containing caffeine and Citrus aurantium (bitter orange) extract. The primary protoalkaloidal ingredient in bitter orange extract is p-synephrine which has some structural similarities to ephedrine and nor-epinephrine, but exhibits markedly different pharmacokinetic and receptor binding properties. The goal of this study was to investigate the cardiovascular effects of a product containing caffeine, bitter orange extract (p-synephrine) and green tea extract in mildly overweight individuals. Fourteen female and nine male subjects (age 24.7 ±7.4 yrs, BMI: 26.6 ±3.8) volunteered in this randomized, placebo-controlled, crossover, double-blind designed study. On day one, subjects entered the laboratory following an overnight fast. Heart rate and blood pressure were recorded at 60 min. Expired air was analyzed for the next 10 min of the session. At each of three meals, subjects ingested one capsule that was either a non-caloric placebo or a dietary supplement that contained 13 mg p-synephrine and 176 mg caffeine. On the following day, the subjects returned and repeated the protocol for data collection beginning 60 min after consuming one capsule of the placebo or the dietary supplement. No effects of the dietary supplement on heart rate, systolic and diastolic blood pressure or mean arterial pressure were observed. No between or within group differences were observed when data were analyzed for gender and caffeine usage. A small but significant decrease in resting respiratory exchange ratio was observed for the low caffeine user group in response to the product containing caffeine and p-synephrine. The results of this study indicate that ingestion of a product containing bitter orange extract, caffeine and green tea extract does not lead to increased cardiovascular stress and that fat oxidation may increase in certain populations.

Instructor-paced vs. self-paced skiing modes in older recreational alpine skiers.

Parallel ski steering (PSS), carving in long radii (CLR), and individual technique (IT) skiing modes are mainly used throughout instructor-guided skiing of older recreational skiers. The aims of this study were (a) to determine differences in the physiologic response of older skiers to PSS, CLR, and IT skiing modes, (b) to quantify correlations between rate of perceived exertion (RPE) and the physiologic response, and (c) to analyze the relationship between aerobic capacity, skiing skills, and the blood lactate (LA) response during instructor-guided skiing. Twenty recreational skiers (61.1 ± 5.6 years) performed instructor-paced (PSS and CLR) and self-paced (IT) skiing modes. Heart rate (HR), LA, mean arterial blood pressure (MAP), and RPE were determined during skiing. Skiers skiing skills were judged by expert ski instructors. The aerobic capacity was tested by a physical work capacity test (PWC130) test. Heart rate was lower for PSS (106 ± 15 b · min(-1)), compared to CLR (118 ± 16 b · min(-1)) and IT (120 ± 15 b · min(-1)) skiing modes, both p < 0.001. Lactate levels were 1.45 ± 0.50 mmol · L(-1) for PSS, 1.67 ± 0.61 mmol · L(-1) for CLR, and 2.00 ± 0.74 mmol · L(-1) for IT skiing modes, all p < 0.004. Individual reductions in LA concentrations from 3.9 to 2.6 mmol · L were found, for IT and PSS skiing modes, respectively. No significant correlations were determined between any physiologic variable and RPE. Weak correlations were found between LA and PWC130 results (R2 < 0.114) and between LA and skiing skills (R2 < 0.132). In conclusion, significant reductions in the physiologic response were determined for PSS and CLR, compared with IT skiing modes. Instructor-paced skiing modes may minimize the risk of premature fatigue of skiers with high physiological responses. Those skiers may not perceive their disproportionate higher stress compared with skiers on the low end.

Changes in quadriceps muscle activity during sustained recreational alpine skiing.

During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing) and the last two (POSTskiing) runs was measured from the vastus lateralis (VL) and rectus femoris (RF) using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination) within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs. Key pointsThe frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF.General muscular fatigue, where additional specific fibers have to be recruited due to the reduced power output of other fibers, did not occur.A modified skiing style towards a less functional and hence more uncontrolled skiing technique seems to be a key issue with respect to the influence on muscle recruitment for applied prolonged skiing session.

Quadriceps Muscle Function during Recreational Alpine Skiing.

PURPOSE: Since the introduction of carving skis, muscle activity has been investigated primarily on expert-level skiers with respect to EMG intensities. The three-part aim of this recreational skiing study was to analyze functional differences within the quadriceps muscle, to analyze the topographical influence, and to apply a time-frequency analysis of the EMG intensities using wavelets. METHODS: Seven female subjects performed two runs through a standardized corridor on a slope with different inclinations (13 degrees , 29 degrees , and 21 degrees ). Knee angle and EMG of vastus lateralis (VL) and rectus femoris (RF) of the right leg were measured during the runs. The recorded EMG signal was resolved with a set of 10 wavelets (11-432 Hz) into a time-frequency space. Subsequently, the EMG intensity and mean frequency (MF) were calculated for different time windows (inside leg; outside leg). RESULT: For RF, a significantly higher MF (+15.5%, P = 0.009) but similar EMG intensities were detected in the inside leg compared with the outside leg. For VL, the MF (-9.6%, P = 0.053) and EMG intensities (-54.3%, P = 0.010) were lower in the inside leg compared with the outside leg. Both muscles responded with higher EMG intensities on increasing slope inclination (VL = 90.8%, P = 0.022; RF = 115%, P = 0.01). MF is not directly related to inclination. CONCLUSIONS: Contrary to previously suggested coloading of the inside leg while carving, our results do not support this hypothesis for VL. However, the functional demand for RF in the inside leg is very high when skiing recreationally. The ability of a situation-dependent loading (RF as knee extensor) and unloading (RF as hip flexor) of the inside leg seems to be a crucial point with respect to specific fatigue during a skiing day.

The role of ribose on oxidative stress during hypoxic exercise: a pilot study.

Oxygen free radicals are produced during stress, are unstable, and potentially interact with other cellular components or molecules. This reactivity can influence cellular function, including a prolongation in tissue recovery following exercise. We tested the effect of ribose (d-ribose), a pentose carbohydrate, in a double-blinded, crossover study on markers of free radical production during hypoxic exercise. Seven healthy volunteers cycled at their lactate threshold for 25 minutes while inhaling 16% O(2) with a subsequent 60-minute resting period at room air. Subjects ingested either placebo or 7 g of ribose in 250 mL of water before and after the exercise session. Urinary malondialdehyde (MDA) and plasma reduced glutathione levels increased significantly during placebo ingestion (0.2 +/- 0.03 nM/mg and 0.26 +/- 0.29 microM, respectively) but were lower with ribose supplementation (0.04 +/- 0.03 nM/mg and 0.38 +/- 0.29 microM, respectively; P < .05). Uric acid levels were similar between groups (ribose vs. placebo, 4.55 +/- 0.06 mg/dL vs. 4.67 +/- 0.06 mg/dL). Ribose demonstrated a beneficial trend in lower MDA and reduced glutathione levels during hypoxic stress.

The relationship of heart rate and lactate to cumulative muscle fatigue during recreational alpine skiing.

Common indices of fatigue may not respond similarly between downhill skiing and other activities because of the influence of factors such as snow conditions, changing terrain, and skiing style. The purpose of this study was to investigate the relationship and predictors of common fatigue indices during downhill skiing. Ten healthy female recreational skiers skied for 3 hours under standardized conditions. Feedback on heart rate (HR) and finishing time were given to each skier at the end of each run to maintain a relatively stable load. A chronic stress score (Cstress) was calculated from creatine kinase (CK), cortisol, and isometric endurance. Finishing times and HR from runs 2, 12, and 24 were similar. Heart rate averaged 82% of HRmax. Heart rate was an insignificant predictor (p = .65) and was poorly correlated (r = 0.16) to Cstress. Blood lactate (LA) was a significant predictor of the Cstress (p = 0.05; r = 0.62). Pre- to postskiing peak forces were not different (p = 0.62), but skiers experienced a significant decrease in isometric endurance from 106.1 +/- 29.6 to 93.2 +/- 24.0 seconds. Endurance decreased by 13%, whereas cortisol and CK increased by 16 and 42%, respectively. Isometric contraction endurance and blood LA were significant predictors of overall stress. Individual compensation mechanisms and skiing style contributed to highly variable responses during skiing. Whereas HR may indicate stress within a given run, it is not a significant indicator of Cstress and fatigue during recreational alpine skiing. However, the cumulative stress variables and LA can be used in field testing of skiers. It is suggested that LA is a practical on-hill marker of chronic stress.

Assessment of Hematological and Biochemical parameters with extended D-Ribose ingestion.

D-ribose, a naturally occurring pentose carbohydrate, has been shown to replenish high- energy phosphates following myocardial ischemia and high intensity, repetitive exercise. Human studies have mainly involved short-term assessment, including potential toxicity. Reports describing adverse effects of D-ribose with prolonged ingestion have been lacking. Therefore, this study assessed the toxicity of extended consumption of D-ribose in healthy adults. Nineteen subjects ingested 20 grams/Day (10 grams, twice a Day) of ribose with serial measurements of biochemical and hematological parameters at Days 0, 7, and 14. No significant toxic changes over the 14-day assessment period occurred in complete blood count, albumin, alkaline phosphatase, gamma glutamyltransferase, alanine amiotransferase, and aspartate aminotransferase. However, D-ribose did produce an asymptomatic, mild hypoglycemia of short duration. Uric acid levels increased at Day 7, but decreased to baseline values by Day 14. D-ribose consumption for 14 days appears not to produce significant toxic changes in both hematological and biochemical parameters in healthy human volunteers.

Protein added to a sports drink improves fluid retention.

The purpose of this study was to compare fluid retention of carbohydrate plus protein, a carbohydrate-only, and water following 2.5% body weight (BW) loss. Thirteen subjects dehydrated to 2.5% of BW, then ingested a CHO (6%) plus protein drink (1.5%; CP), a 6% CHO drink, or water (WA) at a volume equal to BW loss during a 3-h recovery. Fluid retention was significantly greater for CP (88 +/- 4.7%) than CHO (75 +/- 14.6%), which was greater than WA (53 +/- 16.1%). Serum and urine osmolalities were greater for CP (284.7 +/- 5.0; 569.4 +/- 291.4 mOsm/kg) than CHO (282.6 +/- 5.2; 472.9 +/- 291.5 mOsm/kg) which were greater than WA (280.6 +/- 5.9, 303.7 +/- 251.5 mOsm/kg). Results indicate that fluid retention for CP was 15% greater than CHO and 40% greater than WA. Water ingestion led to a dilution of the serum and resulted in only 53% fluid retention.

The effects of ad libitum fluid ingestion on fluid balance during alpine skiing in recreational skiers.

The aim of this study was to assess the influence of ad libitum water ingestion, using a back-mounted hydration system (BMHS), on fluid balance during alpine skiing. Fourteen skiers skied on two different days. On one day, seven skiers ingested water during skiing via the BMHS and the other seven skiers refrained from fluid ingestion during skiing until the midday break (NW trial). On the second day, the trials were reversed. Results indicated that when skiers used the BMHS they drank significantly more water than during the NW trials (2.0 +/- 0.9 vs. 0.78 +/- 0.4 litres). However, skiers drank significantly more at the midday break during the NW trials than during the BMHS trials (0.78 +/- 0.4 vs. 0.4 +/- 0.2 litres). Percent change in plasma volume was less during the BMHS trials than during the NW trials (-0.1 +/- 5.3 vs. -4.9 +/- 5.2%), urine osmolality was maintained in the BMHS trials but rose from 295 +/- 80 to 818 +/- 168 mOsm . kg(-1) at midday during the NW trials, and body mass loss was minimized during the BMHS trials compared with the NW trials (0.4 +/- 0.4 vs. 1.1 +/- 0.2 kg). Skiers reported that they felt significantly better when they ingested water during the BMHS trials. In conclusion, a back-mounted hydration system allowed the skiers to maintain hydration status.

Muscle damage, fluid ingestion, and energy supplementation during recreational alpine skiing.

This study examined energy and fluid supplementation on indices of muscle damage during alpine skiing. Skiers were assigned to a carbohydrate-protein (CP), placebo (PL), or no fluid (NF) group. CP and PL ingested 1.62 L during and after skiing. Myoglobin did not change from pre-skiing (PS) to 2 h post-skiing (2PS) for CP (24.8 +/- 1.4 and 25.6 +/- 1.6 ng/mL), but rose significantly from 26.4 +/- 1.3 to 40.0 +/- 2.8 ng/mL for PL and from 29.0 +/- 1.3 to 82.9 +/- 3.6 ng/mL for NF. Creatine kinase was maintained from PRE to 2 PS for CP, but increased significantly from 117 +/- 7.2 to 174 +/- 43.4 U/L for PL and from 126 +/- 23.2 to 243 +/- 34.3 U/L for NF. This study demonstrates that ingestion of a CP beverage minimized muscle damage indices during skiing compared to PL and NF and that ingesting fluids may also minimize muscle damage compared to a NF condition.