Sit-and-reach flexibility and running economy of men and women collegiate distance runners.
ABSTRACT Flexibility has been controversially suggested as one of the biomechanical factors contributing to the variability observed in running economy among distance runners. The purpose of this investigation was to determine the magnitude of the relationship between sit-and-reach flexibility and running economy in men and women. Eight collegiate distance runners (4 men and 4 women) served as subjects for this correlational study (age = 19.9 +/- 1.25 years; VO2max = 63.2 +/- 3.4 mlxkgxmin). Each subject's flexibility was measured using the standard sit-and-reach test, and running economy was recorded during an incremental maximal treadmill test at both absolute (men = 241.2 mxmin; women = 198.32 mxmin) and relative (10-km pace) velocities. Statistical analyses indicated a significant relationship between sit-and-reach scores and running economy at an absolute velocity (r = 0.826, p <or= 0.05), as well as a significant sex difference in sit-and-reach scores (p <or= 0.05). The significant relationship demonstrates that the less flexible distance runners tended to be more economical, possibly as a result of the energy-efficient function of the elastic components in the muscles and tendons during the stretch-shortening cycle.
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ABSTRACT: Running economy (RE) represents a complex interplay of physiological and biomechanical factors that is typically defined as the energy demand for a given velocity of submaximal running and expressed as the submaximal oxygen uptake (VO2) at a given running velocity. This review considered a wide range of acute and chronic interventions that have been investigated with respect to improving economy by augmenting one or more components of the metabolic, cardiorespiratory, biomechanical or neuromuscular systems. Improvements in RE have traditionally been achieved through endurance training. Endurance training in runners leads to a wide range of physiological responses, and it is very likely that these characteristics of running training will influence RE. Training history and training volume have been suggested to be important factors in improving RE, while uphill and level-ground high-intensity interval training represent frequently prescribed forms of training that may elicit further enhancements in economy. More recently, research has demonstrated short-term resistance and plyometric training has resulted in enhanced RE. This improvement in RE has been hypothesized to be a result of enhanced neuromuscular characteristics. Altitude acclimatization results in both central and peripheral adaptations that improve oxygen delivery and utilization, mechanisms that potentially could improve RE. Other strategies, such as stretching should not be discounted as a training modality in order to prevent injuries; however, it appears that there is an optimal degree of flexibility and stiffness required to maximize RE. Several nutritional interventions have also received attention for their effects on reducing oxygen demand during exercise, most notably dietary nitrates and caffeine. It is clear that a range of training and passive interventions may improve RE, and researchers should concentrate their investigative efforts on more fully understanding the types and mechanisms that affect RE and the practicality and extent to which RE can be improved outside the laboratory.Sports Medicine 08/2014; DOI:10.1007/s40279-014-0246-y · 5.32 Impact Factor
International Journal of Morphology 09/2012; 30(3):1065-1070. DOI:10.4067/S0717-95022012000300049 · 0.20 Impact Factor
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ABSTRACT: Abstract Background: [Formula: see text] prediction models have not focused on children and adolescents from South Africa and have not included various demographic factors as possible predictors. Aim: The purpose of this study was, therefore, to determine whether a valid [Formula: see text] prediction function can be developed from several anthropometric measurements and demographic factors of a cohort of adolescents in South Africa. Subjects and methods: A total of 214 adolescent boys (n = 88) and girls (n = 126) (15.82 ± 0.68 years) were selected. Demographic, sport and maturation data were collected by means of questionnaires, whereas anthropometric measurements were taken by accredited anthropometrists and the 20-m Shuttle Run Test (SRT) executed to determine indirect [Formula: see text] values. A forward stepwise multiple regression analysis was performed to identify the cluster analysis reduced [Formula: see text] predictors and a cross-validation was performed in order to validate the prediction function. Results: Muscle mass percentage, sport participation level, stature, hip circumference and ectomorphy acted as significant predictors (p < 0.05) of the adolescents' indirect, 20-m SRT [Formula: see text] values. Seventy per cent of the variance in the indirect, 20-m SRT [Formula: see text] values could be explained by this model. Cross-validation also confirmed the model's validity. Conclusion: Results indicate that the [Formula: see text] of adolescents from different racial backgrounds, living areas and gender groups can be accurately predicted by making use of a population-specific model.Annals of Human Biology 07/2014; 42(2):1-9. DOI:10.3109/03014460.2014.930173 · 1.15 Impact Factor