Acute Effects Of Reducing Vertical Displacement And Step Frequency On Running Economy
2012 (English)In: Journal of Strength and Conditioning Research, ISSN 1064-8011, Vol. 26, no 8, 2065-2070 p.Article in journal (Refereed) Published
This work studies the immediate effects of altering the vertical displacement of CoM (VD) and step frequency (SF) on the metabolic cost of level treadmill running at 16 km·h on sixteen male runners. Alterations of VD, SF and the product VD SF was induced using a novel feedback system which presents target and current values to the runner by visual or auditory display. Target values were set to 5 and 10% reductions from individual baseline values. Results were expressed as relative changes from baseline values.Alterations led to an increase in metabolic cost in most cases, measured as VO2 uptake per minute and kg body mass. Correlations were weak. Still, linear multiple regression revealed a positive coefficient (0.28) for the relationship between VD SF and VO2. Separate rank correlation tests showed negative correlation (τ = -0.19) between SF and VO2 and positive correlation (τ = -0.16) between VD and VO2. There is a coupling between VD and SF caused by the mechanics of running, hence isolated reduction of either factor was hard to achieve. The linear model also showed a negative coefficient for the relationship between the height of center of mass above ground (CoMh) and VO2.The effect size was small (multiple R-squared 0.07 and 0.12). Still the results indicate that reducing VD SF by reducing vertical displacement can have a positive effect on running economy, but a concurrent reduction in CoMh may reduce or diminish the positive effect. Mid- and long-term effects of altering the technique should also be studied.
Place, publisher, year, edition, pages
2012. Vol. 26, no 8, 2065-2070 p.
biomechanics, locomotion, energy expenditure, feedback training
Sport and Fitness Sciences Physiology
IdentifiersURN: urn:nbn:se:kth:diva-83682DOI: 10.1519/JSC.0b013e318239f87fISI: 000306858000008PubMedID: 2202784ScopusID: 2-s2.0-84866043767OAI: oai:DiVA.org:kth-83682DiVA: diva2:498959
QC 201208242012-02-122012-02-122012-08-24Bibliographically approved