Papers by Øyvind Sandbakk
Gender differences in power production, energetic capacity and efficiency of elite cross-country skiers during whole-body, upper-body, and arm poling
European journal of applied physiology, Jan 17, 2015
To characterize gender differences in power output, energetic capacity and exercise efficiency du... more To characterize gender differences in power output, energetic capacity and exercise efficiency during whole-body (WP), upper-body (UP), and arm poling (AP). Ten male and ten female elite cross-country skiers, matched for international performance level, completed three incremental submaximal tests and a 3-min self-paced performance test on a Concept2 SkiErg. Power output, cardiorespiratory and kinematic variables were monitored. Body composition was determined by dual-energy X-ray absorptiometry. The men demonstrated 87, 97 and 103 % higher power output, and 51, 65 and 71 % higher VO2peak (L min(-1)) than the women during WP, UP and AP, respectively, while utilizing ~10 % more of their running VO2max in all modes (all P < 0.001). The men had 35, 38 and 59 % more lean mass in the whole body, upper body and arms (all P < 0.001). The men exhibited greater shoulder and elbow extension at the start of poling and greater trunk flexion at the end of poling (all P < 0.05). The rela...
PLOS ONE, 2015
In the current study, we evaluated the impact of exercise intensity on gender differences in uppe... more In the current study, we evaluated the impact of exercise intensity on gender differences in upper-body poling among cross-country skiers, as well as the associated differences in aerobic capacity, maximal strength, body composition, technique and extent of training. Eight male and eight female elite skiers, gender-matched for level of performance by FIS points, carried out a 4-min submaximal, and a 3-min and 30-sec maximal all-out test of isolated upper-body double poling on a Concept2 ski ergometer. Maximal upper-body power and strength (1RM) were determined with a pull-down exercise. In addition, body composition was assessed with a DXA scan and training during the previous six months quantified from diaries. Relative to the corresponding female values (defined as 100%), the power output produced by the men was 88%, 95% and 108% higher during the submaximal, 3-min and 30-sec tests, respectively, and peak power in the pull-down strength exercise was 118% higher (all P<0.001). During the ergometer tests the work performed per cycle by the men was 97%, 102% and 91% greater, respectively, and the men elevated their cycle rate to a greater extent at higher intensities (both P<0.01). Furthermore, men had a 61% higher VO 2 peak, 58% higher 1RM, relatively larger upper-body mass (61% vs 56%) and reported considerably more upper-body strength and endurance training (all P<0.05). In conclusion, gender differences in upper-body power among cross-country skiers augmented as the intensity of exercise increased. The gender differences observed here are greater than those reported previously for both lower-and whole-body sports and coincided with greater peak aerobic capacity and maximal upper-body strength, relatively more muscle mass in the upper-body, and more extensive training of upper-body strength and endurance among the male skiers.
Speed and Heart Rate Profiles in Skating and Classical Cross-country Skiing Competitions
International journal of sports physiology and performance, Jan 11, 2015
To compare the speed and heart rate profiles during international skating and classical competiti... more To compare the speed and heart rate profiles during international skating and classical competitions in male and female world-class cross-country skiers. Four male and five female skiers performed individual time-trials of 15 km (men) and 10 km (women) in the skating and classical techniques on two consecutive days. Races were performed on the same 5-km course. The course was mapped with GPS and a barometer to provide a valid course and elevation profile. Time, speed and heart rate were determined for uphill, flat and downhill terrains throughout the entire competition by wearing a GPS and a heart rate monitor. Time in uphill, flat and downhill terrain was ~55, 15-20 and 25-30% of the total race time for both techniques and genders. The average speed differences between skating and classical skiing were 9 and 11% for men and women respectively; and these values were 12 and 15% for uphill, 8 and 13% for flat (all P<0.05) and 2 and 1% for downhill terrain. The average speed for men...
International journal of sports physiology and performance, 2014
This study examined the influence of turn radius on velocity and energy profiles when skidding an... more This study examined the influence of turn radius on velocity and energy profiles when skidding and step turning during more and less effective downhill turns while cross-country skiing. Thirteen elite female cross-country skiers performed single turns with a 9- or 12-m radius using the skidding technique and a 12- or 15-m radius with step turning. Mechanical parameters were monitored using a real-time kinematic Global Navigation Satellite System and video analysis. Step turning was more effective during all phases of a turn, leading to higher velocities than skidding (P < .05). With both techniques, a greater radius was associated with higher velocity (P < .05), but the quality of turning, as assessed on the basis of energy characteristics, was the same. More effective skidding turns involved more pronounced deceleration early in the turn and maintenance of higher velocity thereafter, while more effective step turning involved lower energy dissipation during the latter half of...
International journal of sports physiology and performance, 2014
Cross-country (XC) skiing has been an Olympic event since the first Winter Games in Chamonix, Fra... more Cross-country (XC) skiing has been an Olympic event since the first Winter Games in Chamonix, France, in 1924. Due to more effective training and tremendous improvements in equipment and track preparation, the speed of Olympic XC-ski races has increased more than that of any other Olympic endurance sport. Moreover, pursuit, mass-start, and sprint races have been introduced. Indeed, 10 of the 12 current Olympic competitions in XC skiing involve mass starts, in which tactics play a major role and the outcome is often decided in the final sprint. Accordingly, reappraisal of the success factors for performance in this context is required. The very high aerobic capacity (VO2max) of many of today's world-class skiers is similar that of their predecessors. At the same time, the new events provide more opportunities to profit from anaerobic capacity, upper-body power, high-speed techniques, and "tactical flexibility." The wide range of speeds and slopes involved in XC skiing r...
Theoretical biology & medical modelling, 2012
Based on a literature review, the current study aimed to construct mathematical models of lactate... more Based on a literature review, the current study aimed to construct mathematical models of lactate production and removal in both muscles and blood during steady state and at varying intensities during whole-body exercise. In order to experimentally test the models in dynamic situations, a cross-country skier performed laboratory tests while treadmill roller skiing, from where work rate, aerobic power and blood lactate concentration were measured. A two-compartment simulation model for blood lactate production and removal was constructed. The simulated and experimental data differed less than 0.5 mmol/L both during steady state and varying sub-maximal intensities. However, the simulation model for lactate removal after high exercise intensities seems to require further examination. Overall, the simulation models of lactate production and removal provide useful insight into the parameters that affect blood lactate response, and specifically how blood lactate concentration during pract...
Human Movement Science, 2014
This study analyzed the biomechanical and physiological effects of the arm swing in roller ski sk... more This study analyzed the biomechanical and physiological effects of the arm swing in roller ski skating, and compared leg-skating (i.e. ski skating without poles) using a pronounced arm swing (SWING) with leg-skating using locked arms (LOCKED). Sixteen elite male cross-country skiers performed submaximal stages at 10, 15 and 20 km h À1 on a 2% inclined treadmill in the two techniques. SWING demonstrated higher peak push-off forces and a higher force impulse at all speeds, but a longer cycle length only at the highest speed (all P < .05), indicating a lower force effectiveness with SWING at the two lowest speeds. Additionally, the flexion-extension movement in the lower limbs was more pronounced for SWING. Oxygen uptake was higher for SWING at the two lowest speeds (both P < .05) without any differences in blood lactate. At the highest speed, oxygen uptake did not differ between SWING and LOCKED, but the RER, blood lactate and ventilation were lower with SWING (all P < .05). Taken together, these results demonstrate that utilizing the arm swing in roller ski skating increases the ski forces and aerobic energy cost at low and moderate speeds, whereas the greater forces at high speed lead to a longer cycle length and smaller anaerobic contribution.
Frontiers in Physiology, 2013
The ability to efficiently utilize metabolic energy to produce work is a key factor for endurance... more The ability to efficiently utilize metabolic energy to produce work is a key factor for endurance performance. The present study investigated the effects of incline, performance level, and gender on the gross mechanical efficiency during roller ski skating. Thirty-one male and nineteen female elite cross-country skiers performed a 5-min submaximal session at approximately 75% of VO 2 peak on a 5% inclined treadmill using the G3 skating technique. Thereafter, a 5-min session on a 12% incline using the G2 skating technique was performed at a similar work rate. Gross efficiency was calculated as the external work rate against rolling friction and gravity divided by the metabolic rate using gas exchange. Performance level was determined by the amount of skating FIS points [the Federation of International Skiing (FIS) approved scoring system for ski racing] where fewer points indicate a higher performance level. Strong significant correlations between work rate and metabolic rate within both inclines and gender were revealed (r = −0.89 to 0.98 and P < 0.05 in all cases). Gross efficiency was higher at the steeper incline, both for men (17.1 ± 0.4 vs. 15.8 ± 0.5%, P < 0.05) and women (16.9 ± 0.5 vs. 15.7 ± 0.4%, P < 0.05), but without any gender differences being apparent. Significant correlations between gross efficiency and performance level were found for both inclines and genders (r = −0.65 to 0.81 and P < 0.05 in all cases). The current study demonstrated that cross-country skiers of both genders used less metabolic energy to perform the same amount of work at steeper inclines, and that the better ranked elite male and female skiers skied more efficiently.
European Journal of Applied Physiology, 2014
Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Ber... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".
The Physiology and Biomechanics of Upper-Body Repeated Sprints in Ice Sledge Hockey
International Journal of Sports Physiology and Performance, 2014
To investigate performance and the associated physiological and biomechanical responses during up... more To investigate performance and the associated physiological and biomechanical responses during upper-body repeated-sprint work. Twelve male ice sledge hockey players from the Norwegian national team performed eight 30-m sprints with start every 30 s and an active recovery between sprints. Time was captured every 10 m by photocells, cycle length and rate were determined by video analyses, and heart rate and blood lactate concentration were measured by conventional methods. The percentage sprint decrement was 7% over the 8 trials, with significant reductions in performance from the previous trial already on the second trial (all P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Furthermore, cycle rate was reduced by 9% over the 8 trials (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Similar changes in performance and kinematic patterns were evident for all 10-m phases of the sprints. Heart rate gradually increased to 94% of maximal (178 ± 10 beats/min) over the 8 trials, and the mean reduction in heart rate was 7 ± 2 beats/min during the 22-24 s of active recovery for all trials (all P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). The blood lactate concentration increased to the athletes&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; maximal levels over the 8 sprints (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). This is the first study to investigate performance, physiological, and biomechanical aspects of self-propelled upper-body repeated-sprint work. The observed sprint decrement over the 8 trials was associated with reductions in cycle rates and high physiological demands. However, no kinematic and physiological characteristics were significantly correlated to repeated-sprint ability or the sprint decrement.
The effects of skiing velocity on mechanical aspects of diagonal cross-country skiing
Sports Biomechanics, 2014
Cycle and force characteristics were examined in 11 elite male cross-country skiers using the dia... more Cycle and force characteristics were examined in 11 elite male cross-country skiers using the diagonal stride technique while skiing uphill (7.5°) on snow at moderate (3.5 ± 0.3 m/s), high (4.5 ± 0.4 m/s), and maximal (5.6 ± 0.6 m/s) velocities. Video analysis (50 Hz) was combined with plantar (leg) force (100 Hz), pole force (1,500 Hz), and photocell measurements. Both cycle rate and cycle length increased from moderate to high velocity, while cycle rate increased and cycle length decreased at maximal compared to high velocity. The kick time decreased 26% from moderate to maximal velocity, reaching 0.14 s at maximal. The relative kick and gliding times were only altered at maximal velocity, where these were longer and shorter, respectively. The rate of force development increased with higher velocity. At maximal velocity, sprint-specialists were 14% faster than distance-specialists due to greater cycle rate, peak leg force, and rate of leg force development. In conclusion, large peak leg forces were applied rapidly across all velocities and the shorter relative gliding and longer relative kick phases at maximal velocity allow maintenance of kick duration for force generation. These results emphasise the importance of rapid leg force generation in diagonal skiing.
European Journal of Applied Physiology, 2015
sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressi... more sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressively decreased (P < 0.05). m. triceps brachii and m. latissimus dorsi were highly desaturated already after the first sprint (all P < 0.05), whereas the response was delayed for m. biceps brachii and m. vastus lateralis. Correspondingly, increases in VO 2 mainly occurred over the first two sprints (P < 0.05) and plateaued at approximately 75 % of VO 2peak . 1RM correlated with power during the first four sprints and with average sprint power (r = 0.71-0.80, all P < 0.05), whereas VO 2peak correlated with power in the last three sprints (r = 0.60-0.71, all P < 0.05). Conclusions The main decrement in upper-body sprint performance was evident in the first five sprints, followed by highly desaturated muscles and a plateau in pulmonary oxygen uptake already after the first 2-3 sprints. While high maximal strength seems important for producing power, aerobic capacity correlates with power in the last sprints.
Nitric Oxide, 2014
This study examined the effects of acute supplementation with L-arginine and nitrate on running e... more This study examined the effects of acute supplementation with L-arginine and nitrate on running economy, endurance and sprint performance in endurance-trained athletes. In a randomised cross-over, doubleblinded design we compared the effects of combined supplementation with 6 g L-arginine and 614 mg nitrate against 614 mg nitrate alone and placebo in nine male elite cross-country skiers (age 18 ± 0 years, VO2max 69.3 ± 5.8 ml·min −1 ·kg −1 ). After a 48-hour standardisation of nutrition and exercise the athletes were tested for plasma nitrate and nitrite concentrations, blood pressure, submaximal running economy at 10 km·h −1 and 14 km·h −1 at 1% incline and 180 m as well as 5-km time-trial running performances. Plasma nitrite concentration following L-arginine + nitrate supplementation (319 ± 54 nmol·L −1 ) did not differ from nitrate alone (328 ± 107 nmol·L −1 ), and both were higher than placebo (149 ± 64 nmol·L −1 , p < 0.01). There were no differences in physiological responses during submaximal running or in 5-km performance between treatments. The plasma nitrite concentrations indicate greater nitric oxide availability both following acute supplementation of L-arginine + nitrate and with nitrate alone compared to placebo, but no additional effect was revealed when L-arginine was added to nitrate. Still, there were no effects of supplementation on exercise economy or endurance running performance in endurance-trained cross-country skiers.
Open Access Journal of Sports Medicine, 2014
The current study adapts the power balance model to simulate cross-country skiing on varying terr... more The current study adapts the power balance model to simulate cross-country skiing on varying terrain. We assumed that the skier's locomotive power at a self-chosen pace is a function of speed, which is impacted by friction, incline, air drag, and mass. An elite male skier's position along the track during ski skating was simulated and compared with his experimental data. As input values in the model, air drag and friction were estimated from the literature based on the skier's mass, snow conditions, and speed. We regard the fit as good, since the difference in racing time between simulations and measurements was 2 seconds of the 815 seconds racing time, with acceptable fit both in uphill and downhill terrain. Using this model, we estimated the influence of changes in various factors such as air drag, friction, and body mass on performance.
European Journal of Applied Physiology, 2011
This investigation was designed to analyze the time-trial (STT) in an international cross-country... more This investigation was designed to analyze the time-trial (STT) in an international cross-country skiing sprint skating competition for (1) overall STT performance and relative contributions of time spent in different sections of terrain, (2) work rate and kinematics on uphill terrain, and (3) relationships to physiological and kinematic parameters while treadmill roller ski skating. Total time and times in nine different sections of terrain by 12 worldclass male sprint skiers were determined, along with work rate and kinematics for one specific uphill section. In addition, peak oxygen uptake (VO 2peak ), gross efficiency (GE), peak speed (V peak ), and kinematics in skating were measured. Times on the last two uphill and two final flat sections were correlated to overall STT performance (r = *-0.80, P \ 0.001). For the selected uphill section, speed was correlated to cycle length (r = -0.75, P \ 0.01) and the estimated work rate was approximately 160% of peak aerobic power. VO 2peak , GE, V peak , and peak cycle length were all correlated to STT performance (r = *-0.85, P \ 0.001). More specifically, VO 2peak and GE were correlated to the last two uphill and two final flat section times, whereas V peak and peak cycle length were correlated to times in all uphill, flat, and curved sections except for the initial section (r = *-0.80, P \ 0.01). Performances on uphill and flat terrain in the latter part were the most significant determinants of overall STT performance. Peak oxygen uptake, efficiency, peak speed, and peak cycle length were strongly correlated to overall STT performance, as well as to performance in different sections of the race.
Analysis of sprint cross-country skiing using a differential global navigation satellite system
European Journal of Applied Physiology, 2010
The purpose was to examine skiing velocities, gear choice (G2-7) and cycle rates during a skating... more The purpose was to examine skiing velocities, gear choice (G2-7) and cycle rates during a skating sprint time trial (STT) and their relationships to performance, as well as to examine relationships between aerobic power, body composition and maximal skiing velocity versus STT performance. Nine male elite cross-country skiers performed three tests on snow: (1) Maximum velocity test (V (max)) performed using G3 skating, (2) V (max) test performed using double poling (DP) technique and (3) a STT over 1,425 m. Additional measurements of VO(2max) during roller skiing and body composition using iDXA were made. Differential global navigation satellite system data were used for position and velocity and synchronized with video during STT. The STT encompassed a large velocity range (2.9-12.9 m s(-1)) and multiple transitions (21-34) between skiing gears. Skiing velocity in the uphill sections was related to gear selection between G2 and G3. STT performance was most strongly correlated to uphill time (r = 0.92, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), the percentage use of G2 (r = -0.72, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), and DP V (max) (r = -0.71, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). The velocity decrease in the uphills from lap 1 to lap 2 was correlated with VO(2max) (r = -0.78, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). V (max) in DP and G3 were related to percent of racing time using G3. In conclusion, the sprint skiing performance was mainly related to uphill performance, greater use of the G3 technique, and higher DP and G3 maximum velocities. Additionally, VO(2max) was related to the ability to maintain racing velocity in the uphills and lean body mass was related to starting velocity and DP maximal speed.
European Journal of Applied Physiology, 2012
Gender differences in performance by elite endurance athletes, including runners, track cyclists ... more Gender differences in performance by elite endurance athletes, including runners, track cyclists and speed skaters, have been shown to be approximately 12%. The present study was designed to examine gender differences in physiological responses and kinematics associated with sprint cross-country skiing. Eight male and eight female elite sprint cross-country skiers, matched for performance, carried out a submaximal test, a test of maximal aerobic capacity (VO 2max ) and a shorter test of maximal treadmill speed (V max ) during treadmill roller skiing utilizing the G3 skating technique. The men attained 17% higher speeds during both the VO 2max and the V max tests (P \ 0.05 in both cases), differences that were reduced to 9% upon normalization for fat-free body mass. Furthermore, the men exhibited 14 and 7% higher VO 2max relative to total and fatfree body mass, respectively (P \ 0.05 in both cases). The gross efficiency was similar for both gender groups. At the same absolute speed, men employed 11% longer cycles at lower rates, and at peak speed, 21% longer cycle lengths (P \ 0.05 in all cases). The current study documents approximately 5% larger gender differences in performance and VO 2max than those reported for comparable endurance sports. These differences reflect primarily the higher VO 2max and lower percentage of body fat in men, since no gender differences in the ability to convert metabolic rate into work rate and speed were observed. With regards to kinematics, the gender difference in performance was explained by cycle length, not by cycle rate.
European Journal of Applied Physiology, 2010
The present study investigated metabolic rate (MR) and gross eYciency (GE) at moderate and high w... more The present study investigated metabolic rate (MR) and gross eYciency (GE) at moderate and high work rates, and the relationships to gross kinematics and physical characteristics in elite cross-country skiers. Eight world class (WC) and eight national level (NL) male sprint crosscountry skiers performed three 5-min stages using the skating G3 technique, whilst roller skiing on a treadmill. GE was calculated by dividing work rate by MR. Work rate was calculated as the sum of power against gravity and frictional rolling forces. MR was calculated using gas exchange and blood lactate values. Gross kinematics, i.e. cycle length (CL) and cycle rate (CR) were measured by video analysis. Furthermore, the skiers were tested for time to exhaustion (TTE), peak oxygen uptake (VO 2peak ), and maximal speed (V max ) on the treadmill, and maximal strength in the laboratory. Individual performance level in sprint skating was determined by FIS points. WC skiers did not diVer in aerobic MR, but showed lower anaerobic MR and higher GE than NL skiers at a given speed (all P < 0.05). Moreover, WC skiers skated with longer CL and had higher V max and TTE (all P < 0.05). In conclusion, the present study shows that WC skiers are more eYcient than NL skiers, and it is proposed that this might be due to a better technique and to technique-speciWc power.
Theoretical Biology and Medical Modelling, 2012
Background: This study investigated two different mathematical models for the kinetics of anaerob... more Background: This study investigated two different mathematical models for the kinetics of anaerobic power. Model 1 assumes that the work power is linear with the work rate, while Model 2 assumes a linear relationship between the alactic anaerobic power and the rate of change of the aerobic power. In order to test these models, a cross country skier ran with poles on a treadmill at different exercise intensities. The aerobic power, based on the measured oxygen uptake, was used as input to the models, whereas the simulated blood lactate concentration was compared with experimental results. Thereafter, the metabolic rate from phosphocreatine break down was calculated theoretically. Finally, the models were used to compare phosphocreatine break down during continuous and interval exercises.
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Papers by Øyvind Sandbakk