The Effect of Muscular Endurance on Running Economy (original) (raw)
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Nicol et al SJMSS 1991 Effects of marathon fatigue on running kinematics and economy
A group of 8 experienced 20to 35-year-old (mean 30) endurance runners (1 woman and 7 men) volunteered for the experiment. Their sport was either marathon or triathlon. The group weight averaged 68 (59-93) kg and height 177 (168-190) cm. Experimental design The experimental design included different tests repeated for each subject on 2 successive sessions, day 1 and day 2, separated by a period of 4 d. The
Determination of muscular fatigue in elite runners
European Journal of Applied Physiology, 2005
This study analyses the changes in the electromyographic activity (EMG) of six major muscles of the leg during an incremental running test carried out on a treadmill. These muscles, the gluteus maximus (GM), biceps femoris (BF), vastus lateralis (VL), rectus femoris (RF), tibialis anterior (TA) and gastrocnemius (Ga) are known to have quite different functions during running. The aim of this study was to develop a methodology adapted to the analysis of integrated EMG (iEMG) running results, and to test the chronology of the onset of fatigue of the major muscles involved in running. Nine well-trained subjects [VO2max 76 (2.9) ml.min_1.kg_1] took part in this study. They completed a running protocol consisting of 4 min stages, incrementally increasing in speed until exhaustion. The EMG signal was recorded during ten bursts of activation analysed separately at 45 s and 3 min 40 s of each stage. During running, consideration of the alteration in stride frequency with either an increase in speed or the onset of fatigue appears to be an indispensable part of the assessment of muscular fatigue. This allows the comparison of muscular activation between the various stage speeds by the use of common working units. Distance seems to be the only working unit that allows this comparison and thus the determination of the appearance of fatigue during running. The biarticular hip-mobilising muscles (RF and BF), which present two different bursts of activation during one running cycle, are the muscles that show the earliest signs of fatigue.
Journal of Strength and Conditioning Research, 2004
Hayes, P.R., S.J. Bowen, and E.J. Davies. The relationships between local muscular endurance and kinematic changes during a run to exhaustion at vV O 2 max. J. Strength Cond. Res. 18(4): 000-000. 2004.-A recent study suggested that runners who maintain a stable running style are able to run for longer at vV O 2 max velocity (vV O 2 max). This may be because of the capacity of various muscle groups to maintain their functions despite the onset of fatigue. The purpose of this study was to examine the relationship between local muscular endurance of both the hip and knee extensor and flexor muscle groups and the kinematic changes during a run to exhaustion at vV O 2 max. Six subelite runners (age 24.2 Ϯ 4.2) participated in this study; they were considered as a homogeneous group based upon their vV O 2 max scores (coeffeicient of variation ϭ 3.9%). They performed an incremental protocol to determine vV O 2 max, a series of isokinetic tests to determine the local muscular endurance of both knee and hip flexors and extensors, and a run to exhaustion at vV O 2 max. The change in kinematic variables between the beginning and the end of the run were correlated with the measures of muscular endurance. Several statistically significant negative correlations emerged between the change in stride length and concentric hip extension (HE con ), r ϭ Ϫ0.934; eccentric hip extension (HE ecc ), r ϭ Ϫ0.818; eccentric knee flexion (KF ecc ), r ϭ Ϫ0.957; and change in maximum hip extension (⌬ max HE), r ϭ Ϫ0.857; and ⌬ max HE with HE con , r ϭ Ϫ0.846. We concluded that the local muscular endurance of both HE con and KF ecc are important in maintaining a stable running style.
European Journal of Applied Physiology, 2007
The aim of the present study was to examine muscle mechanical characteristics before and after a marathon race. Eight elite runners underwent a pre-test 1 week before the marathon and post-tests 30 min, two and fiveday-post-marathon. Actual marathon race performance was 2:34:40 ± 0:04:13. Energy expenditure at marathon pace (EE Mpace ) was elevated 4% post-marathon (pre: 4,465 ± 91 vs. post 4,638 ± 91 J kg bodyweight -1 km -1 , P < 0.05), but was lowered by 6 and 9.5% two-and five-day-postmarathon compared to EE Mpace pre-marathon. Countermovement jump (CMJ) power decreased 13% post-marathon (pre: 21.5 ± 0.9 vs. post: 18.9 ± 1.2 W kg -1 ; P < 0.05) and remained depressed two-(18%) and five-day (12%) post-marathon. CMJ force was unaltered across all four tests occasions. Knee extensor and plantar flexor maximal voluntary contraction (MVC) decreased from 176.6 ± 9.5 to 136.7 ± 16.8 Nm and 144.9 ± 8.7 to 119.2 ± 15.1 Nm post-marathon corresponding to 22 and 17%, respectively (P < 0.05). No significant changes were detected in evoked contractile parameters, except a 25% increase in force at 5 Hz, and low frequency fatigue was not observed. In conclusion, leg muscle power decreased acutely post-marathon race and recovered very slowly. The post-marathon increase in EE Mpace might be attributed to a reduction in stretch shortening cycle efficiency. Finally, since MVC was reduced after the marathon race without any marked changes in evoked muscle contractile properties, the strength fatigue experienced by the subjects in this study seems to be related to central rather than peripheral mechanisms.
Maximal Strength Training Improves Running Economy in Distance Runners
Medicine & Science in Sports & Exercise, 2008
Purpose: The present study investigated the effect of maximal strength training on running economy (RE) at 70% of maximal oxygen consumption (V O 2max ) and time to exhaustion at maximal aerobic speed (MAS). Responses in one repetition maximum (1RM) and rate of force development (RFD) in half-squats, maximal oxygen consumption, RE, and time to exhaustion at MAS were examined. Methods: Seventeen well-trained (nine male and eight female) runners were randomly assigned into either an intervention or a control group. The intervention group (four males and four females) performed half-squats, four sets of four repetitions maximum, three times per week for 8 wk, as a supplement to their normal endurance training. The control group continued their normal endurance training during the same period. Results: The intervention manifested significant improvements in 1RM (33.2%), RFD (26.0%), RE (5.0%), and time to exhaustion at MAS (21.3%). No changes were found in V O 2max or body weight. The control group exhibited no changes from pre to post values in any of the parameters. Conclusion: Maximal strength training for 8 wk improved RE and increased time to exhaustion at MAS among welltrained, long-distance runners, without change in maximal oxygen uptake or body weight.
European Journal of Applied Physiology
We investigated the changes in constant velocity spring-mass behavior after high intensity sprint fatigue in order to better interpret the results recently reported after ultra-long distance (ULD) exercises. Our hypothesis was that after repeated sprints (RS), subjects may likely experience losses of force such as after ULD, but the necessity to modify their running pattern to attenuate the overall impact at each step (such as after ULD) may not be present. Eleven male subjects performed four sets of five 6-s sprints with 24-s recovery between sprints and 3 min between sets, on a sprint treadmill and on a bicycle ergometer. For each session, their running mechanics and spring-mass characteristics were measured at 10 and 20 km h−1 on an instrumented treadmill before and after RS. Two-way (period and velocity) ANOVAs showed that high-intensity fatigue did not induce any change in the constant velocity running pattern at low or high velocity, after both running and cycling RS, despite significant decreases (P < 0.001) in maximal power (−27.1 ± 8.2% after running RS and −15.4 ± 11.5 % after cycling RS) and knee extensors maximal voluntary force (−18.8 ± 6.7 % after running RS and −15.0 ± 7.6 % after cycling RS). These results bring indirect support to the hypothesis put forward in recent ULD studies that the changes in running mechanics observed after ULD are likely not related to the decrease in strength capabilities, but rather to the necessity for subjects to adopt a protective running pattern.
Effects of a 2-Hour Run on Metabolic Economy and Lower Extremity Strength in Men and Women
Journal of Orthopaedic & Sports Physical Therapy, 1998
mong the determinants of successful distance running performance are maximal oxygen , consumption (VO,,,,) , lactate and ventilatory thresholds, lean body mass, and running economy (14). Running economy, described as the oxygen cost of running at a given submaximal speed (ml/m/kg), contributes significantly to distance running performance (6, 7,14). Numerous variables may contribute to running economy. Gender (7). age (15), biomechanics (4), flexibility (12), environmental condition (24), and body temperature (16,25) have been suggested as factors that influence economy. The effect of previous bouts of maximal running on running economy has also been examined. Morgan et al found that a 30-minute maximal run did not affect the oxygen cost of running on subsequent days in men (21). The literature suggests that economy during extended bouts of exercise may be influenced by a number of mechanisms. Hamilton et al showed a pronounced rise in oxygen uptake (VO,), which was preventable with intravenous glucose infusion while cycling for 2 hours (13). An upward T O , drift" during exercise has also been demonstrated in men during treadmill exercise with no fluid replacement (l6,23,26). Nielsen et a1 found that the increased total Changes in running economy, or the oxygen cost of running at a given submaximal speed (ml/m/kg), during prolonged exercise have been well described in men but not in women. Lower extremity strength changes associated with prolonged exercise have never been addressed. We examined changes in running economy and strength following a 2-hour run in eight men and eight women. Knee and hip strength were measured pre-and post-running. Peak oxygen consumption (V02pak) and oxygen consumption at ventilatory threshold were determined. Subjects then ran for 2 hours at an intensity which elicited ventilatory threshold (68.7% vs. 66.6% of VOZpak for men and women, p = 0.5). Water was ingested at a rate of 0.5% of body weight each half hour. Oxygen uptake (V02) and respiratory exchange ratio were measured initially and at 1 and 2 hours. Body weight declined in the men @ = 0.001) but not in the women (p = 0.12). Running economy decreased in the men (p < 0.001) but not in the women @ = 0.084). At 2 hours of running knee flexion and extension strength declined significantly in the men only (effect of gender x time, p < 0.014), but hip flexion, abduction, and adduction strength declined in both genders. Decreased knee extensodflexor strength was evident in men only, while decreased hip strength was independent of gender. We conclude that 2 hours of running produced changes in knee strength and running economy in men only.
Physiological determinants of endurance exercise performance
Journal of Science and Medicine in Sport, 1999
Performance in endurance events is typically evaluated by the power or velocity that can be maintained for durations of 30 rain. to four hours. The two main by-products of intense and prolonged oxidative metabolism that can limit performance are the accumulation of hydrogen ion (i.e. lactic acidosis) and heat (i.e. hypeI~hermia). A model for endurance performance is presented that revolves around identification of the lactate threshold velocity which is presented as a function of numerous morphological components as well as gross mechanical efficiency. When cycling at 80 RPM, gross mechanical efficiency is positively related to Type I muscle fiber composition, which has great potential to improve endurance performance. Endurance performance can also be influenced by altering the availability of oxygen and blood glucose during exercise. The latter need forms the basis for ingesting carbohydrate at 30-60 grams per hour during exercise. In laboratory simulations of performance, athletes fatigue due to hyperthermia when esophageal is approximately 40°C, in association with near maximal heart rate and perceived exertion. It is likely that the central nervous system is involved in the aetiology of fatigue from hyperthermia. Dehydration during exercise promotes hypel~lermia by reducing skin blood flow, sweating rate and thus heat dissipation. The combination of dehydration and hyperthermia during exercise causes large reductions in cardiac output and blood flow to the exercising musculature, and thus has a large potential to impair endurance performance. Endurance performance is optimized when training is aimed specifically at developing individual components of the model presented and nutritional supplementation prevents hypoglycemia and attenuates dehydration and hypelChermia. Indeed, the challenge at the transition to a new millennium is to synergistically integrate these physiological factors in training and competition.
Frontiers in Bioengineering and Biotechnology, 2020
Purpose: To investigate changes in hip and knee strength, kinematics, and running variability following two energy expenditure matched training runs; a medium intensity continuous run (MICR) and a high intensity interval training session (HIIT). Methods: Twenty (10 Females, 10 Males) healthy master class runners were recruited. Each participant completed the HIIT consisting of six repetitions of 800 m with a 1:1 work: rest ratio. The MICR duration was set to match energy expenditure of the HIIT session. Hip and knee muscular strength were examined pre and post both HIIT and MICR. Kinematics and running variability for hip and knee, along with spatiotemporal parameters were assessed at start and end of each run-type. Changes in variables were examined using both 2 × 2 ANOVAs with repeated measures and on an individual level when the change in a variable exceeded the minimum detectable change (MDC). Results: All strength measures exhibited significant reductions at the hip and knee (P < 0.05) with time for both run-types; 12% following HIIT, 10.6% post MICR. Hip frontal plane kinematics increased post run for both maximum angle (P < 0.001) and range of motion (P = 0.003). Runners exhibited increased running variability for nearly all variables, with the HIIT having a greater effect. Individual assessment revealed that not all runners were effected post run and that following HIIT more runners had reduced muscular strength, altered kinematics and increased running variability. Conclusion: Runners exhibited fatigue induced changes following typical training runs, which could potentially present risk of injury development. Group and individual assessment revealed different findings where the use of MDC is recommended over that of P-values.
PeerJ, 2018
Background The percentage of sustained maximal oxygen uptake and the running economy are important factors that determine the running success of endurance athletes. Running economy is defined as the oxygen uptake required to run at a given speed and depends on metabolic, cardiorespiratory, biomechanical, neuromuscular, and anthropometric factors. With regard to anthropometric characteristics, total body mass seems to be a crucial factor for the running economy. Moreover, neuromuscular components, especially knee muscular strength and the strength balance ratio, also seem to be critical for the running economy. In addition to knee muscle strength, hip muscle strength is also an important contributor to running performance on level or hilly ground. However, the relationship between running economy and the hip muscles is unknown. Thus the aim of the present study was to verify whether hip flexor and extensor isokinetic peak torque, the isokinetic strength balance ratio, total body mass...