Physiological demands of competitive elite cross-country skiing

Introduction Researchers have, for decades, contributed to an increased collective understanding of the physiological demands in cross-country skiing; however, almost all of these studies have used either non-elite subjects and/or performances that emulate cross-country skiing. To establish the physiological demands of cross-country skiing, it is important to relate the investigated physiological variables to the competitive performance of elite skiers. The overall aim of this doctoral thesis was, therefore, to investigate the external validity of physiological test variables to determine the physiological demands in competitive elite cross-country skiing. Methods The subjects in Study I – IV were elite male (I – III) and female (III – IV) cross-country skiers. In all studies, the relationship between test variables (general and ski-specific) and competitive performances (i.e. the results from competitions or the overall ski-ranking points of the International Ski Federation (FIS) for sprint (FISsprint) and distance (FISdist) races) were analysed. Test variables reflecting the subject’s general strength, upper-body and whole-body oxygen uptake, oxygen uptake and work intensity at the lactate threshold, mean upper-body power, lean mass, and maximal double-poling speed were investigated. Results The ability to maintain a high work rate without accumulating lactate is an indicator of distance performance, independent of sex (I, IV). Independent of sex, high oxygen uptake in whole-body and upper-body exercise was important for both sprint (II, IV) and distance (I, IV) performance. The maximal double-poling speed and 60-s double-poling mean power output were indicators of sprint (IV) and distance performance (I), respectively. Lean mass was correlated with distance performance for women (III), whereas correlations were found between lean mass and sprint performance among both male and female skiers (III). Moreover, no correlations between distance performance and test variables were derived from tests of knee-extension peak torque, vertical jumps, or double poling on a ski-ergometer with 20-s and 360-s durations (I), whereas gross efficiency while treadmill roller skiing showed no correlation with either distance or sprint performance in cross-country skiing (IV). Conclusion The results in this thesis show that, depending on discipline and sex, maximal and peak oxygen uptake, work intensity at the lactate threshold, lean mass, double-poling mean power output, and double-poling maximal speed are all externally valid physiological test variables for evaluation of performance capability among elite cross-country skiers; however, to optimally indicate performance capability different test-variable expressions should be used; in general, the absolute expression appears to be a better indicator of competitive sprint performance whereas the influence of body mass should be considered when evaluating competitive distance performance capability of elite cross-country skiers.

The importance of body-mass exponent optimization for evaluation of performance capability in cross-country skiing

Introduction Performance in cross-country skiing is influenced by the skier’s ability to continuously produce propelling forces and force magnitude in relation to the net external forces. A surrogate indicator of the “power supply” in cross-country skiing would be a physiological variable that reflects an important performance-related capability, whereas the body mass itself is an indicator of the “power demand” experienced by the skier. To adequately evaluate an elite skier’s performance capability, it is essential to establish the optimal ratio between the physiological variable and body mass. The overall aim of this doctoral thesis was to investigate the importance of body-mass exponent optimization for the evaluation of performance capability in cross-country skiing. Methods In total, 83 elite cross-country skiers (56 men and 27 women) volunteered to participate in the four studies. The physiological variables of maximal oxygen uptake (V̇O2max) and oxygen uptake corresponding to a blood-lactate concentration of 4 mmol∙l-1 (V̇O2obla) were determined while treadmill roller skiing using the diagonal-stride technique; mean oxygen uptake (V̇O2dp) and upper-body power output (Ẇ) were determined during double-poling tests using a ski-ergometer. Competitive performance data for elite male skiers were collected from two 15-km classical-technique skiing competitions and a 1.25-km sprint prologue; additionally, a 2-km double-poling roller-skiing time trial using the double-poling technique was used as an indicator of upper-body performance capability among elite male and female junior skiers. Power-function modelling was used to explain the race and time-trial speeds based on the physiological variables and body mass. Results The optimal V̇O2max-to-mass ratios to explain 15-km race speed were V̇O2max divided by body mass raised to the 0.48 and 0.53 power, and these models explained 68% and 69% of the variance in mean skiing speed, respectively; moreover, the 95% confidence intervals (CI) for the body-mass exponents did not include either 0 or 1. For the modelling of race speed in the sprint prologue, body mass failed to contribute to the models based on V̇O2max, V̇O2obla, and V̇O2dp. The upper-body power output-to-body mass ratio that optimally explained time-trial speed was Ẇ ∙ m-0.57 and the model explained 63% of the variance in speed. Conclusions The results in this thesis suggest that V̇O2max divided by the square root of body mass should be used as an indicator of performance in 15-km classical-technique races among elite male skiers rather than the absolute or simple ratio-standard scaled expression. To optimally explain an elite male skier’s performance capability in sprint prologues, power-function models based on oxygen-uptake variables expressed absolutely are recommended. Moreover, to evaluate elite junior skiers’ performance capabilities in 2-km double-poling roller-skiing time trials, it is recommended that Ẇ divided by the square root of body mass should be used rather than absolute or simple ratio-standard scaled expression of power output.

Optimal V. O2max-to-mass ratio for predicting 15 km performance among elite male cross-country skiers

The aim of this study was 1) to validate the 0.5 body-mass exponent for maximal oxygen uptake (V. O2max) as the optimal predictor of performance in a 15 km classical-technique skiing competition among elite male cross-country skiers and 2) to evaluate the influence of distance covered on the body-mass exponent for V. O2max among elite male skiers. Twenty-four elite male skiers (age: 21.4±3.3 years [mean ± standard deviation]) completed an incremental treadmill roller-skiing test to determine their V. O2max. Performance data were collected from a 15 km classicaltechnique cross-country skiing competition performed on a 5 km course. Power-function modeling (ie, an allometric scaling approach) was used to establish the optimal body-mass exponent for V . O2max to predict the skiing performance. The optimal power-function models were found to be race speed = 8.83⋅(V . O2max m-0.53) 0.66 and lap speed = 5.89⋅(V . O2max m-(0.49+0.018lap)) 0.43e0.010age, which explained 69% and 81% of the variance in skiing speed, respectively. All the variables contributed to the models. Based on the validation results, it may be recommended that V. O2max divided by the square root of body mass (mL⋅min−1 ⋅kg−0.5) should be used when elite male skiers’ performance capability in 15 km classical-technique races is evaluated. Moreover, the body-mass exponent for V . O2max was demonstrated to be influenced by the distance covered, indicating that heavier skiers have a more pronounced positive pacing profile (ie, race speed gradually decreasing throughout the race) compared to that of lighter skiers.

Aerobic power and lean mass are indicators of competitive sprint performance among elite female cross-country skiers

The purpose of this study was to establish the optimal allometric models to predict International Ski Federation’s ski-ranking points for sprint competitions (FISsprint) among elite female cross-country skiers based on maximal oxygen uptake (V̇O2max) and lean mass (LM). Ten elite female cross-country skiers (age: 24.5±2.8 years [mean ± SD]) completed a treadmill roller-skiing test to determine V̇O2max (ie, aerobic power) using the diagonal stride technique, whereas LM (ie, a surrogate indicator of anaerobic capacity) was determined by dual-emission X-ray anthropometry. The subjects’ FISsprint were used as competitive performance measures. Power function modeling was used to predict the skiers’ FISsprint based on V̇O2max, LM, and body mass. The subjects’ test and performance data were as follows: V̇O2max, 4.0±0.3 L min-1; LM, 48.9±4.4 kg; body mass, 64.0±5.2 kg; and FISsprint, 116.4±59.6 points. The following power function models were established for the prediction of FISsprint: 3.91×105 ∙ VO -6.002maxand 6.95×1010 ∙ LM-5.25; these models explained 66% (P=0.0043) and 52% (P=0.019), respectively, of the variance in the FISsprint. Body mass failed to contribute to both models; hence, the models are based on V̇O2max and LM expressed absolutely. The results demonstrate that the physiological variables that reflect aerobic power and anaerobic capacity are important indicators of competitive sprint performance among elite female skiers. To accurately indicate performance capability among elite female skiers, the presented power function models should be used. Skiers whose V̇O2max differs by 1% will differ in their FISsprint by 5.8%, whereas the corresponding 1% difference in LM is related to an FISsprint difference of 5.1%, where both differences are in favor of the skier with higher V̇O2max or LM. It is recommended that coaches use the absolute expression of these variables to monitor skiers’ performance-related training adaptations linked to changes in aerobic power and anaerobic capacity.

Aerobic and anaerobic test performance among elite male football players in different team positions

The purpose was to determine the magnitude of aerobic and anaerobic performance factors among elite male football players in different team positions. Thirty-nine players from the highest Swedish division classified as defenders (n=18), midfield players (n=12) or attackers (n=9) participated. Their mean (± sd) age, height and body mass (bm) were 24.4 (±4.7) years, 1.80 (±5.9)m and 79 (±7.6)kg, respectively. Running economy (RE) and anaerobic threshold (AT) was determined at 10, 12, 14, and 16km/h followed by tests of maximal oxygen uptake (VO2max). Maximal strength (1RM) and average power output (AP) was performed in squat lifting. Squat jump (SJ), counter-movement jump with free arm swing (CMJa), 45m maximal sprint and the Wingate test was performed. Average VO2max for the whole population (WP) was 57.0mL O2•kg-1min-1 . The average AT occurred at about 84% of VO2max. 1RM per kg bm0.67 was 11.9±1.3kg. Average squat power in the whole population at 40% 1RM was 70±9.5W per kg bm0.67 . SJ and CMJa were 38.6±3.8cm and 48.9±4.4cm, respectively. The average sprint time (45m) was 5.78± 0.16s. The AP in the Wingate test was 10.6±0.9W•kg-1 . The average maximal oxygen uptake among players in the highest Swedish division was lower compared to international elite players but the Swedish players were better off concerning the anaerobic threshold and in the anaerobic tests. No significant differences were revealed between defenders, midfielders or attackers concerning the tested parameters presented above.

Running economy and blood lactate accumulation in elite football players with high and low maximal aerobic power

The purpose was to determine running economy and lactate threshold among a selection of male elite football players with high and low aerobic power. Forty male elite football players from the highest Swedish division (“Allsvenskan”) participated in the study. In a test of running economy (RE) and blood lactate accumulation the participants ran four minutes each at 10, 12, 14, and 16 km•h-1 at horizontal level with one minute rest in between each four minutes interval. After the last sub-maximal speed level the participants got two minutes of rest before test of maximal oxygen uptake (VO2max). Players that had a maximal oxygen uptake lower than the average for the total population of 57.0 mL O2•kg-1•minute-1 were assigned to the low aerobic power group (LAP) (n=17). The players that had a VO2max equal to or higher than 57.0 mL O2•kg-1•minute-1 were selected for the high aerobic power group (HAP) (n=23). The VO2max was significantly different between the HAP and LAP group. The average RE, measured as oxygen uptake at 12, 14 and 16km•h-1 was significantly lower but the blood lactate concentration was significantly higher at 14 and 16 km•h-1 for theLAP group compared with the HAP group.

Aerobic and anaerobic test performance among elite male football players in different team positions

The purpose was to determine the magnitude of aerobic and anaerobic performance factors among elite male football players in different team positions. Thirty-nine players from the highest Swedish division classified as defenders (n=18), midfield players (n=12) or attackers (n=9) participated. Their mean (± sd) age, height and body mass (bm) were 24.4 (±4.7) years, 1.80 (±5.9)m and 79 (±7.6)kg, respectively. Running economy (RE) and anaerobic threshold (AT) was determined at 10, 12, 14, and 16km/h followed by tests of maximal oxygen uptake (VO2max). Maximal strength (1RM) and average power output (AP) was performed in squat lifting. Squat jump (SJ), counter-movement jump with free arm swing (CMJa), 45m maximal sprint and the Wingate test was performed. Average VO2max for the whole population (WP) was 57.0mL O2•kg-1min-1. The average AT occurred at about 84% of VO2max. 1RM per kg bm0.67 was 11.9±1.3kg. Average squat power in the whole population at 40% 1RM was70±9.5W per kg bm0.67. SJ and CMJa were 38.6±3.8cm and 48.9±4.4cm,respectively. The average sprint time (45m) was 5.78± 0.16s. The AP in the Wingate test was 10.6±0.9W•kg-1. The average maximal oxygen uptake among players in the highest Swedish division was lower compared to international elite players but the Swedish players were better off concerning the anaerobic threshold and in the anaerobic tests. No significant differences were revealed between defenders, midfielders or attackers concerning the tested parameters presented above.

Elitidrottsproblem? : En kvalitativ studie om elitidrottares karriäravslutning

This paper used a qualitative technique from a social scientific perspective, a model based on Hewitt and his theory of the self-concept. The purpose of this study was to investigate why some elite athletes experience troublesome periods after their career ending. Interviews were performed with five elite athletes with varying experiences after career ending. The length of the elite athlete careers vary between 7 to 17 years. Two groups were made based upon experiences after career ending. Group 1 had experienced problems, for example suicide tendency, and group 2 had not. The result shows that a troublesome period can come up independently of career ending. The self-concept was investigated during the career and further different kind of variables which could affect the self as training and competition, social relations both before and after termination from sport. Result indicates that an individual in group 2 who has a high complexity in the self-concept based upon significant others outside the elite sport during the career copes with the new situation after career ending much better than group 1 who have not. To build up the self based only upon significant others in the elite sport seems to give expression in a strengthen self. Intensity in training and competition did not have a connection with a troublesome period after retirement from sport but it could prevent establishing contact with others outside the elite sport and reduce a high complexity in the self-concept. The result further shows that elite athletes who practise an individual sport trains in to a greater extent than elite athletes in a seasonal sport. Result also shows that practising a sport with one day off a week, contributes to better opportunities for developing a higher complexity in the self-concept. Suspicions has also rouse that practising an elite sport on the highest level can lead to extensive focusing that further leads to social isolation from individuals outside elite sport. To build up the self upon significant others outside elite sport during the career and keep in touch with significant others from elite sport after the career seems to be the key to avoid problems after the career ending. Suggestions about further investigations are made to see if medial exposure and status can affect the self.

Faktorer som påverkar uppkomsten av hot och våld inom psykiatrin

Syftet med denna systematiska litteraturstudie var att beskriva faktorer som påverkade uppkomsten av hot och våld inom psykiatrin. Till resultatet har författarna använt sig av tjugoen vetenskapliga artiklar som hämtats ur Högskolan dalarnas databaser ELIN, Academic Search Elite samt Cinahl. Sökord i olika kombinationer har använts för att få fram relevant litteratur till studien. De sökord som användes var violence, nursing, mental health nurses, aggressive patients, aggressive behaviour, psychiatric units, patients, factors, prevention, aggression, nurses, psychiatric, management, psychiatry och causes. Även manuell sökning i tidskrifter har gjorts. Artiklarna skulle vara publicerade tidigast år 2000 om inte tidigare studier ansågs innehålla relevant fakta för studien. Granskning av artiklarna genomfördes med hjälp av granskningsmallar. Resultatet visade att bemötandet av patienter inom psykiatrisk vård var av stor betydelse för om hotfulla och våldsamma incidenter skulle inträffa. Att som vårdpersonal försöka förstå anledningen till den uppkomna situationen kunde leda till att dessa situationer kunde undvikas. Patienterna upplevde ofta att personalen inte lyssnade och detta var en vanlig orsak till att våldsamma incidenter uppstod. Vårdpersonalen ansåg istället att patientens sjukdom var orsaken till uppkomsten av hot och våld. På avdelningar där patienter med paranoida och psykotiska tendenser var intagna ökade risken för våldsamma situationer. Patienterna upplevde ofta tiden på den psykiatriska avdelningen som långtråkig och det påverkade stämningen. Både vårdpersonal och patienter ansåg att mer aktiviteter skulle minska aggressionen på avdelningen.

Unga kvinnors upplevelse av beslutsprocessen vid abort

Syfte: Att belysa den unga kvinnans upplevelse av beslutsprocessen vid valet av abort, som underlag för helhetsförståelse vid omvårdnaden av denna. Metod: Litteraturstudie som redovisar resultat från artiklar med kvalitativ- och kvantitativ ansats samt två systematiska litteraturstudier. Datainsamling skedde genom databaserna ElinDalarna, Academic Search Elite (EBSCO) och SveMed+. Sökord som använts är - abortion, psychological aspects, decision-making, experience och omvårdnad. Huvudresultat: I beslutsprocessen präglades kvinnorna av ambivalens. Känslor vid oönskad graviditet skiljde sig inte mycket mellan olika kvinnor. Även kvinnor som var säkra i sitt beslut upplevde ambivalens. Abort som en lösning på oönskad graviditet hade sitt pris hur beslutsam kvinnan var. Ett abortbeslut var för många kvinnor en smärtsam nödvändighet och många kvinnor upplevde ångest vid abortbeslutet. Känslor och erfarenhet som kvinnor upplevde i beslutsprocessen och vid abort påverkde kvinnornas känsloliv resten av deras liv. Kvinnors konsultationsmönster, angående sin oönskade graviditet, är annorluna än vid andra stora händelser i livet. Kvinnor sökte ofta stöd i sitt beslutsfattande. Det var viktigt att sjuksköterskan, i mötet med den abortsökande kvinna, förhåller sig neutral i tal samt använda öppna frågor. Slutsats: Under förespegling att kvinnan har ett fritt val gör hon sitt val av abort. Detta val innehåller allehanda komplexa känslor och paradoxer. Det är viktigt med medvetenhet om detta, bland sjuksköterskor, för att ge adekvat och neutral omvårdnad.

Information och undervisning vid omvårdnad av patient med hjärt- kärlsjukdomar : En Litteraturstudie

Syfte: Syftet med denna litteraturstudie var att undersöka hur information når fram till patienter med hjärt-kärlsjukdomar. Metod: Systematisk litteraturstudie. 15 artiklar, både kvalitativa och kvantitativa, granskades till resultatsdelen efter sökningar genom databaserna Academic Search Elite, CINAHL och PubMed, samt sökmotorn Elin@Dalarna. Artiklarna som använts är från 2002 och framåt. De hade en kvalitet som var antingen medel eller hög efter en granskning med hjälp av granskningsmallar för kvalitetsbedömning.Huvudresultat: Det fanns behov för patienter och deras anhöriga att få information om patientens tillstånd och kommande besvär. Riskuppfattning, riskbearbetning, känslor, personliga värderingar, social press, miljö och ekonomiska förutsättningar bidrog som barriärer för att få informationen att nå fram till patienterna. Patienterna uppgav att det behövdes förbättringar angående information och undervisning. Det fanns många områden där förbättringar kunde göras angående information och undervisning vid hjärt- och kärlsjukdomar. Ibland ges inte den informationen som patienterna tycker att de behöver.

Mjuk massage som symtomlindring inom cancervård : Litteraturstudie

Syftet med denna studie var att söka kunskap om användningsområden för mjuk massage inom cancervård som en komplementär behandlingsmetod till medicinsk behandling. Metoden var en litteraturstudie där artiklar söktes i databaserna Academic Search Elite och PubMed via Högskolan Dalarnas nätverk. 12 artiklar, varav nio kvantitativa och tre kvalitativa, ligger till grund för litteraturstudien. Artiklarna var publicerade mellan åren 2000-2010. Artiklarna kvalitetsgranskades efter vedertagna granskningsmallar. Studiedeltagarnas symtom bildade följande kategorier under analysprocessen: existentiella upplevelser, smärta, oro, depression/nedstämdhet, illamående och sömnlöshet. Resultatet visade att mjuk massage kan lindra symtom och negativa upplevelser inom cancervård. Mjuk massage kan användas inom cancervård till att bekräfta patienterna existentiellt, deltagarna blev lugnare i kropp och själ, kände sig värdefulla, omhändertagna och mindre ensamma. En tydlig smärtlindrande effekt sågs i samtliga studier där massagens inverkan på smärta studerades. Depression, nedstämdhet, oro och illamående lindrades i majoriteten av studierna.

Patientens upplevelse av den perioperativa dialogen : En litteraturöversikt

Syfte: Att beskriva hur patienten upplevde den perioperativa dialogen och dess information.Metod: Studien genomfördes som en litteraturöversikt. De vetenskapliga artiklarna söktes via databaserna Cinahl, Pubmed, Medline och Academic Search Elite. Uppsatsförfattarna valde ut 16 artiklar låg till grund för resultatet. Artiklarna bestod av både kvalitativa och kvantitativa studier. Artiklarnas kvalitet bedömdes utifrån granskningsmallar.Resultat: I studier kunde utläsas att patienterna hade goda upplevelser av den perioperativa dialogen. Patienterna kände sig delaktiga i sin egen omvårdnad och behandling samt upplevde att operationssjuksköterskan såg dem som viktiga i omvårdnadsprocessen. Patienterna blev sedda som individer och inte som objekt. Patienterna kände även en samhörighet med operationssjuksköterskan. Detta gjorde att patienterna kände sig trygga och kunde lämna över ansvaret till operationssjuksköterskan. Resultatet visade även att det fanns brister i informationsgivningen samt att olika vårdkategorier fokuserade på olika innehåll i den perioperativa informationen. Patienterna upplevde ett ökat informationsbehov rörande operationen samt uppföljning postoperativt av operationspersonal.Slutsats: Den perioperativa dialogen hade ett stort värde för patienterna. Brist på preoperativ information ledde till en oförberedd och otrygg patient. Att helt frångå en viktig bit i patienternas omvårdnad ledde till en upplevelse av att inte vara delaktig i sin egen situation. Den postoperativa uppföljningen visade sig vara viktig för patienternas välbefinnande.

Aktiviteters påverkan på livssituationen hos äldre i särskilt boende : En litteraturöversikt

Syfte: Att identifiera vilka aktiviteter som var vanligt förekommande på särskilt boende utifrån litteraturen och vilka effekter de hade på äldres livssituation. Metod: Studien genomfördes som en litteraturöversikt och artiklar söktes genom databaserna Pubmed, CINAHL with Full Text och Academic Search Elite. Studiens resultat innehåller 18 antal artiklar. Resultat: Olika sociala och fysiska aktiviteter hade en positiv inverkan på livskvalitén, men även på de boendes upplevelser av ensamhet. Deras fysiska förmåga förbättrades också i form av att de lättare kunde utföra aktiviteter i dagliga livet (ADL). Fem olika kategorier med aktiviteter skapades. Dessa var trädgårdsprogram, fysisk aktivitet, interaktion med djur, sociala aktiviteter och musik. De olika aktiviteterna hade även en positiv inverkan på äldre med demenssjukdomar i form av minskad agitation och störande beteende. Slutsats: Aktiviteters förekomst på särskilt boende bidrar till en förbättrad livssituation. Äldre bör erbjudas möjlighet att delta i olika sociala och fysiska aktiviteter.