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Biomechanical influenced differences in O2 extraction in diagonal skiing: arm versus leg
Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. (Swedish Winter Sports Research Centre)
Department of Sport Science and Kinesiology, University of Salzburg, Austria.
Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. (Swedish Winter Sports Research Centre)ORCID iD: 0000-0002-3814-6246
2010 (English)In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 42, no 10, p. 1899-1908Article in journal (Refereed) Published
Abstract [en]

Biomechanically Influenced Differences in O-2 Extraction in Diagonal Skiing: Arm versus Leg. Med. Sci. Sports Exerc., Vol. 42, No. 10, pp. 1899-1908, 2010. Purpose: This study aimed to determine whether the differences in oxygen extraction and lactate concentration in arms and legs during cross-country skiing are related to muscle activation or force production and how these differences are influenced by a reduction in exercise intensity. Methods: Nine well-trained male cross-country skiers (age = 22 +/- 3 yr, (V) over dotO(2max) = 5.3 +/- 0.3 L.min(-1) and 69 +/- 3 mL.kg(-1).min(-1)) performed diagonal skiing on a treadmill for 3 min at 90% followed by 6 min at 70% of (V) over dotO(2max). During the final minute of each workload, arterial, femoral, and subclavian venous blood was collected for determination of blood gases, pH, and lactate. EMG was recorded from six upper-and lower-body muscles, and leg and pole forces were measured. Cardiorespiratory variables were monitored continuously. Results: Oxygen extraction in the legs was higher than that in the arms at both 90% and 70% of (V) over dotO(2max) (92% +/- 3% vs 85% +/- 6%, P < 0.05 and 90% +/- 3% vs 78% +/- 8%, P < 0.001). This reduction with decreased workload was more pronounced in the arms (-9.8% +/- 7.7% vs -3.2% +/- 3.2%, P < 0.01). EMGRMS for the arms was higher, and pole ground contact time was greater than the corresponding values for the legs (both P < 0.01). At both intensities, the blood lactate concentration was higher in the subclavian than that in the femoral vein but was lowered more in the subclavian vein when intensity was reduced (all P < 0.001). Conclusions: The higher muscle activation (percentage of maximal voluntary isometric contraction) in the arms and the longer ground contact time of the poles than the legs contribute to the lower oxygen extraction and elevated blood lactate concentration in the arms in diagonal skiing. The better lactate recovery in the arms than that in the legs is aided by greater reductions in muscle activation and pole force when exercise intensity is reduced.

Place, publisher, year, edition, pages
Lippincott Williams & Wilkins , 2010. Vol. 42, no 10, p. 1899-1908
Keywords [en]
CROSS-COUNTRY SKIING, EMG, FORCE, LACTATE, OXYGEN CONSUMPTION
National Category
Sport and Fitness Sciences Physiology
Identifiers
URN: urn:nbn:se:miun:diva-10877DOI: 10.1249/MSS.0b013e3181da4339ISI: 000282188300013PubMedID: 20216469Scopus ID: 2-s2.0-77957333501OAI: oai:DiVA.org:miun-10877DiVA, id: diva2:284352
Projects
Integrative Human PhysiologyIntegrative Physiologi & BiomechanicsAvailable from: 2010-01-06 Created: 2010-01-06 Last updated: 2018-01-12Bibliographically approved
In thesis
1. Metabolic and Cardiovascular Responses During Variable Intensity Exercise
Open this publication in new window or tab >>Metabolic and Cardiovascular Responses During Variable Intensity Exercise
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Previous research investigating endurance sports from a physiological perspectivehas mainly used constant or graded exercise protocols, although the nature ofsports like cross-country skiing and road cycling leads to continuous variations inworkload. Current knowledge is thus limited as regards physiological responses tovariations in exercise intensity. Therefore, the overall objective of the present thesiswas to investigate cardiovascular and metabolic responses to fluctuations inexercise intensity during exercise. The thesis is based on four studies (Studies I-IV);the first two studies use a variable intensity protocol with cardiorespiratory andblood measurements during cycling (Study I) and diagonal skiing (Study II). InStudy III one-legged exercise was used to investigate muscle blood flow duringvariable intensity exercise using PET scanning, and Study IV was performed toinvestigate the transition from high to low exercise intensity in diagonal skiing,with both physiological and biomechanical measurements. The current thesisdemonstrates that the reduction in blood lactate concentration after high-intensityworkloads is an important performance characteristic of prolonged variableintensity exercise while cycling and diagonal skiing (Studies I-II). Furthermore,during diagonal skiing, superior blood lactate recovery was associated with a highaerobic power (VO2max) (Study II). Respiratory variables such as VE/VO2, VE/VCO2and RER recovered independently of VO2max and did not reflect the blood lactate oracid base levels during variable intensity exercise during either cycling or diagonalskiing (Studies I-II). There was an upward drift in HR over time, but not inpulmonary VO2, with variable intensity exercise during both prolonged cyclingand diagonal skiing. As a result, the linear HR-VO2 relationship that wasestablished with a graded protocol was not present during variable intensityexercise (Studies I-II). In Study III, blood flow heterogeneity during one-leggedexercise increased when the exercise intensity decreased, but remained unchangedbetween the high intensity workloads. Furthermore, there was an excessiveincrease in muscular VO2 in the consecutive high-intensity workloads, mainlyexplained by increased O2 extraction, as O2 delivery and blood flow remainedunchanged. In diagonal skiing (Study IV) the arms had a lower O2 extraction thanthe legs, which could partly be explained by their longer contact phase along withmuch higher muscle activation. Furthermore, in Study IV, the O2 extraction in botharms and legs was at the upper limit during the high intensity workload with nofurther margin for increase. This could explain why no excessive increase inpulmonary VO2 occurred during diagonal skiing (Study II), as increased O2extraction is suggested to be the main reason for this excessive increase in VO2(Study III).

Place, publisher, year, edition, pages
Sundsvall: Mittuniversitetet, 2010
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 86
Keywords
cross-country skiing, cycling, heart rate, lactate, O2 extraction, O2 uptake, performance, ventilation
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-11744 (URN)978-91-86073-76-3 (ISBN)
Public defence
2010-06-16, Q221, Östersund, 10:30 (English)
Available from: 2010-07-01 Created: 2010-06-21 Last updated: 2013-11-21Bibliographically approved

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Björklund, GlennHolmberg, Hans-Christer

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