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EFFECTS OF STATIC STRETCHING ON ENERGY COST AND RUNNING ENDURANCE PERFORMANCE
JACOB M. WILSON, LYNDSEY M. HORNBUCKLE, JEONG-SU KIM, CARLOS UGRINOWITSCH, SANG-ROK LEE, MICHAEL C. ZOURDOS, BRIAN SOMMER, AND LYNN B. PANTON
Department of Nutrition, Food and Exercise Sciences, The Florida State University, Tallahassee, Florida

ABSTRACT
Wilson, JM, Hornbuckle, LM, Kim, J.-S, Ugrinowitsch, C, Lee,S.-R, Zourdos, MC, Sommer, B, and Panton, LB. Effects of static stretching on energy cost and running endurance performance. J Strength Cond Res 24(9): 2274–2279, 2010—Stretching before anaerobic events has resulted in declines in performance; however, the immediate effects of stretching on endurance performance have not been investigated. This study investigated the effects of static stretchingon energy cost and endurance performance in trained male runners. Ten trained male distance runners aged 25 6 7 years with an average _ VO2max of 63.8 6 2.8 ml/kg/min were recruited. Participants reported to the laboratory on 3 separate days. On day 1, _ anthropometrics and VO2max were measured. On days 2 and 3, participants performed a 60-minute treadmill run randomly under stretching ornonstretching conditions separated by at least 1 week. Stretching consisted of 16 minutes of static stretching using 5 exercises for the major lower body muscle groups, whereas nonstretching consisted of 16 minutes of _ quiet sitting. The run consisted of a 30-minute 65% VO2max preload followed by a 30-minute performance run where participants ran as far as possible without viewing distance or speed.Total calories expended were determined for the 30minute preload run, whereas performance was measured as distance covered in the performance run. Performance was significantly greater in the nonstretching (6.0 6 1.1 km) vs. the stretching (5.8 6 1.0 km) condition (p , 0.05), with significantly greater energy expenditure during the stretching compared with the nonstretching condition (425 6 50 vs. 405 650 kcals). Our findings suggest that stretching before an endurance event may lower endurance performance and increase the energy cost of running.

INTRODUCTION

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KEY WORDS muscle stiffness, flexibility, economy, sit-andreach, rating of perceived exertion

he ability to effectively use energy is a critical component of endurance performance, particularly among elite athletes. In fact,previous studies have reported a strong association between running economy (RE) (i.e., lower energy consumption at a given velocity) and long-distance performance (15,19). Furthermore, RE seems to be the most important variable to discriminate top-level athletes in a homogeneous group of long-distance runners. Thus, training routines should avoid exercises that may increase the energy cost needed tomaintain a given velocity or to complete a performance task (5). Static stretching exercises are a common part of the warmup routine of several athletes and physical activity practitioners in an attempt to improve performance and reduce the risk of injuries. However, static stretching appears to acutely decrease muscle-force production capacity. For instance, static stretching has been shown todecrease leg press 1repetition maximal tests (3), 20-m sprint performance (16), vertical jumping height (21), and knee-extensor concentric torque (6). In addition to this acute effect, Fowles (9) reported a residual effect in which maximum plantar flexion torque remained depressed even 60 minutes after the stretching routine. These decrements in performance are attributed to greater stressrelaxation of the muscle tissue, which leads to lower muscle-tendon stiffness and strength (13,14). Decreasing strength and muscle-tendon stiffness may be prejudicial to endurance runners because Arampatzis et al. (1) reported that individuals with high muscle strength and muscle-tendon stiffness are more efficient (i.e., higher RE) than individuals with low muscle strength. Therefore, it seems reasonable...