Analysis of physiological and biomechanical factors affecting running economy / 中国组织工程研究

BACKGROUND: Running economy is considered as an important indicator of the performance of endurance athletes, especially long-distance runners. It is usually defined as the energy demand of running at a given speed, and expressed as the oxygen intake at a given speed. OBJECTIVE: To review the existing physiological and biomechanical factors affecting the running economy of runners. METHODS: With “running economy, physiological factors, biomechanical and neuromuscular characteristics, spatiotemporal factors, lower limb kinematic factors, kinetic factors, nutritional interventions” as search terms, PubMed database (1960-2018) was searched to include literatures related to running performance, acute or chronic interventions, and other influencing factors. RESULTS AND CONCLUSION: A total of 113 literatures were obtained. According to the inclusion and exclusion criteria, 58 literatures were analyzed. Current evidence shows that cardiopulmonary function, muscle fiber type, muscle strength, leg stiffness and other physiological factors are related to the improvement of running economy. However, there is no unified conclusion on the relationship between the temperature change of runners and the elastic potential energy and running economy. The biomechanical factors that are beneficial to improve running economy include stride frequency or length, vertical oscillation, lower limb moment of inertia, leg extension when toes are off the ground, and arm swing. However, the contact time between the feet and the ground, trunk inclination and other factors are inconsistent with running economy. Among other influencing factors, high-altitude adaptation can improve running economy; the relationship between extensibility and flexibility and running economy remains to be determined. Some nutritional interventions are also of concern, most notably dietary nitrates. Although most of the factors affecting running economy have been summarized in this paper, future studies can focus on individual runners in order to determine how the athlete’s structure and functional abilities affect running economy, as well as subsequent performance and athletic injuries.

The Effect of Concurrent Plyometric Training Versus Submaximal Aerobic Cycling on Rowing Economy, Peak Power, and Performance in Male High School Rowers.

BACKGROUND: Plyometric training has been shown to increase muscle power, running economy, and performance in athletes. Despite its use by rowing coaches, it is unknown whether plyometrics might improve rowing economy or performance. The purpose was to determine if plyometric training, in conjunction with training on the water, would lead to improved rowing economy and performance. METHODS: Eighteen male high school rowers were assigned to perform 4 weeks of either plyometric training (PLYO, n = 9) or steady-state cycling below ventilatory threshold (endurance, E, n = 9), for 30 min prior to practice on the water (matched for training volume) 3 days per week. Rowing performance was assessed through a 500-m rowing time trial (TT) and peak rowing power (RP), while rowing economy (RE) was assessed by measuring the oxygen cost over four work rates (90, 120, 150, and 180 W). RESULTS: Rowing economy was improved in both PLYO and E (p < 0.05). The 500-m TT performance improved significantly for PLYO (from 99.8 ± 9 s to 94.6 ± 2 s, p < 0.05) but not for E (from 98.8 ± 6 s to 98.7 ± 5 s, p > 0.05). Finally, RP was moderately higher in the PLYO group post-training (E 569 ± 75 W, PLYO 629 ± 51 W, ES = 0.66) CONCLUSIONS: In a season when the athletes performed no rowing sprint training, 4 weeks of plyometric training improved the 500-m rowing performance and moderately improved peak power. This increase in performance may have been mediated by moderate improvements in rowing power, but not economy, and warrants further investigation.

Relationships between unilateral horizontal and vertical drop jumps and 20 m sprint performance.

OBJECTIVES: The purpose of this study was to compare the relationships between horizontal (HDJ) and vertical drop jumps (VDJ) to sprint performance. DESIGN: Exploratory Study. SETTING: Laboratory. PARTICIPANTS: Nineteen male collegiate participants (22.5 ± 3.2 years, 181.1 ± 6.7 cm, 80.3 ± 9.6 kg). MAIN OUTCOME MEASURES: All participants performed VDJ and HDJ from a 20 cm height onto an AMTI force platform sampling at 1200 Hz before performing three 20 m sprints. Sprint times (5, 10, 15, 20, 5-10, 10-15, 15-20 m) were measured using a LAVEG speed gun. RESULTS: All jump and sprint measures showed excellent within session reliability (ICC: 0.954 to 0.99). Pearson's and Spearman's correlations revealed significant (p < 0.01) moderate to high correlations between jump measures and sprint times (R: -0.665 to -0.769). Stepwise multiple regression revealed jump distance normalised by body height (HDJ) was the best predictor for 10, 20, 5-10, 10-15 and 15-20 m sprint times (R(2) = 41%-48%). CONCLUSIONS: HDJ performance measures provide stronger relationships to sprint performance than VDJ's. Thus, HDJ's should be considered in test batteries to monitor training and rehabilitation for athletes in sprint related sports.

A Comparison of the Kinetic and Kinematic Characteristics of Plyometric Drop-Jump and Pendulum Exercises.

The aim of this study was to compare the kinetic and kinematic characteristics of plyometric drop-jump and pendulum exercises. Exercises were filmed (100 Hz) from the sagittal view and manually digitized; the data were smoothed and differentiated using cross-validated quintic splines. Ground reaction force data were sampled using a Kistler force platform sampling at 500 Hz. Differences between movement amplitudes and coordination strategies were assessed using t tests and conjugate cross-correlations. Pendulum exercises involved a greater range of motion at the ankle and knee but less motion at the hip joint than drop-jumps. Although different in absolute terms, the exercises used a similar coordination strategy. Drop-jumps resulted in greater peak vertical ground reaction forces than the pendulum exercises although the latter involved a greater net impulse. The similarity between the movement patterns for the two modes of exercise led to the conclusion that pendulum exercises offer a training stimulus similar to that of drop-jumps.