Journal of Physical Education and Sport

Abstract

IntroductionRunning economy (RE) is defined as the energy cost (EC) for a given velocity of submaximal running and it is determined by measuring the steady condition consumption of oxygen (VO2) and the respiratory exchange ratio (RER) (Saunders et al., 2004). Runners who have a better EC, use less energy and less oxygen ,at the same speed, than runners with poor running economy. There is a strong association between EC and distance running performance, with EC being a better predictor of performance than maximal oxygen uptake (VO2max) in elite runners, who have a similar VO2max (Saunders et al., 2004). A number of physiological and biomechanical factors seem to influence RE and EC, including temperature, heart rate, ventilation, VO2max, age, gender, body mass, muscle fiber type distribution and other biomechanical variables (Morgan et al., 1989; Daniels & Daniels, 1992; Morgan & Craib, 1992; Pate et al., 1989; Saunders et al., 2004). Lower running economy is a result of neuromuscular fitting shortage and the disability of elastic energy utilization. Contrarily, higher running economy is due to better neuromuscular coordination and coordinated movement and it leads to a greater performance. Metabolic adaptations in muscles, with increased density of muscle mitochondria, oxidative enzymes and better ability to store and utilize elastic energy by the muscles lead to a lower EC of running (Saunders et al., 2004).None of the athletes seems to consume 22% more oxygen than high level runners at the same steady condition speed (Costiel, 1986). Comparing high level runners with moderately trained runners, the results show better EC for the first group (Morgan et al., 1992). Long distance runners also present better economy, than semi-distance and sprint runners. It leads to a greater EC, at a 150 to 300 Kcal, in a marathon race for elite runners, compared to moderately trained runners (Conley et al., 1980; Daniels et al., 1992). EC is also correlated with muscle tissue apportion. Cyclists with better energy cost have a greater amount of type I fibers in leg muscles. It is calculated that performance factor of fibers type I is 27 %, and type II is 13% (Coyle et al., 1992, 1999).It has been suggested that a higher percentage of slow-twitch muscle fibres is associated with better running economy. (Bosco et al., 1987; Williams et al., 1987). The relationship between EC and performance is well established for running (Cavanagh & Kram, 1989), walking (Minetti et al., 1995) and cycling (Hagberg et al., 1981). A Treadmill running and cycle ergometry comparison showed similar parameters of the VO2 responses, except for the VO2 slow component, which was significantly greater for cycling than for running (Carter et al., 2000). Oxygen uptake seems to be lower and blood lactate higher for a brief period of intense nonsteady state cycling as compared to uphill running .On the contrary, anaerobic energy cost is higher for cycling, although in terms of work efficiency those two can be similar (Scott et al., 2006). Also metabolic cost of submaximal cycling in different pedalling rates rises in a linear regression with speed and pedal rate (McDaniel et al., 2002). The majority of studies indicate that runners achieve a higher VO2max on treadmill, whereas cyclists can achieve a VO2max value in cycle ergometry similar to that in treadmill running (Millet et al., 2009). An increase of energy cost along with exercise duration had already been observed for prolonged exercises such as running (Davies et al., 1986) and cycling (Lepers et al., 2000). All mountain bike riders (MTB) seem to have similar physical characteristics with climbers (Impellizseri & Marcora, 2007).Although in bibliography there are reports about studies, that examined energy cost and economy of cycling and running, there is no report concerning the comparison in the energy cost of climbers and MTB riders. The aim of the present study was to evaluate and compare the cardiorespiratory performance and energy cost in trained climbers and MTB athletes. …