Factors Affecting Running Economy

Abstract

Running economy, defined as the steady-state VO2 for a given running velocity, has been shown to account for a large and significant proportion of variation in distance-running performance among runners roughly comparable in VO2 max. Despite this recognition, relatively little is known regarding the potpourri of physiological, environmental, structural and mechanical factors potentially associated with a lower aerobic demand of running. Early attempts at quantifying the energy expenditure of exhaustive runs incorporated measurements of oxygen consumption before, during, and after exercise. The validity of this approach has been questioned, however, since recent evidence has demonstrated that only a moderate relationship exists between postexercise VO2 and anaerobic metabolism. The energy demands for submaximal running (i.e. running economy) can be quantified by calculating the steady-state VO2, expressed with respect to body mass and time, for a standardised, submaximal running speed. Since this variable represents the aerobic demand of running, the generation of energy must derive wholly from cell respiration and not from substantial protein catabolism. Research has indicated that at low to moderate work rates, the steady-state energy condition is attained in about 3 minutes. Trained individuals reach steady-state sooner than unfit subjects. While limited by methodological constraints, the existence of a steady-state has also been verified by the lack of blood lactate accumulation and the presence of a respiratory exchange ratio of less than 1.00. The ability of economy, either singly or in combination with VO2 max, to account for a substantial portion of performance variation among trained distance runners and untrained subjects of comparable ability and fitness level has been demonstrated in recent cross-sectional studies. Limited data from short and long term longitudinal research also suggests that endurance running success is linked to training and growth-related improvements in economy. Intraindividual variation in economy has been shown to vary between 2% and 11% for a given speed. Most of this variation can probably be attributed to biological error. While the majority of evidence does not support a gender difference in running economy, data from some studies suggest that males may be more economical than women. Prepubescent children are less economical than older children and adults, whereas older adults exhibit the same trend when compared to younger counterparts. Because of air and wind resistance, the aerobic demands of indoor treadmill running significantly underestimate the cost of overground running, especially at higher speeds.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of intense interval workouts on running economy using three recovery durations

“…Furthermore, at low to moderate work-rates, it is possible that a steady-state condition can be found within three minutes (Whipp & Wasserman, 1972). Nevertheless, Morgan et al (1989b) advised that the length of a RE test should be between six to ten minutes (Morgan et al, 1989b).…”

“…Such limitations are smalJ sample sizes; Jack of multiple economy measures to account for normal intra-individual ( " 42 variation; and faiIure to control factors which may potentially influence RE such as training status, fatigue and circadian variation (Morgan et al, 1989b).…”

“…These studies have shown that improved running economy (RE) results in heightened running performance. Variances in RE among and within cohorts of runners are influenced by many biornechanical, physiological and anthropometric factors (Morgan 1989b;.…”

Oxygen uptake during moderate intensity running: response following a single bout of interval training

“…The interest shown in this area is warranted, since factors affecting VO 2 during moderate-intensity, constant-velocity running are not completely understood (Morgan et al 1989). Also, small differences in VO 2 during moderate-intensity running between individuals have been associated with differences in performance capability (Morgan et al 1989).…”

“…Also, small differences in VO 2 during moderate-intensity running between individuals have been associated with differences in performance capability (Morgan et al 1989). The effect of prior exercise on pulmonary gas exchange variables is also of interest due to the implications for the reliability of measurement of these variables.…”