Abstract：
:To investigate the possible role of elastic potentiation on mechanical efficiency, three male marathon runners were filmed while running on a treadmill at various steady-state speeds ranging from 7.0-22.0 km X h-1. Kinematic and mechanical energy analyses were performed from the film. Expired air was collected for energy expenditure determination. The analysis disclosed that during contact on the treadmill the knee and ankle joints initially had a phase of negative (flexion) angular velocity, followed by a positive velocity. In the hip joint the stretch-shortening cycle of the extensor muscles occurred primarily during the flight phase. The mean vertical and horizontal forces of the negative and positive phases of the contact period increased linearly with the increase in the running speed. The calculated mechanical efficiency of positive work was high but relatively constant (55.1 +/- 12.7%) across all speeds. The absolute contribution of the extra work, which comes from the stored elastic energy to the positive work, increased with running speed; however, its relative value (0.61 +/- 0.09 J X min-1 X kg-1) remained constant at all measured speeds. It is suggested, therefore, that when the flight phase is included in the mechanical energy calculations, the measured efficiency for the positive work reaches a high but constant value in running at low-to-moderate speeds.
journal_name
Med Sci Sports Exercjournal_title
Medicine and science in sports and exerciseauthors
Ito A,Komi PV,Sjödin B,Bosco C,Karlsson Jdoi
10.1249/00005768-198315040-00009subject
Has Abstractpub_date
1983-01-01 00:00:00pages
299-308issue
4eissn
0195-9131issn
1530-0315journal_volume
15pub_type
杂志文章abstract：PURPOSE:The purpose of this study was to investigate the effect of acute ingestion of modafinil (M) on time to exhaustion during high-intensity exercise. Modafinil (M) is a psychostimulant developed to treat narcolepsy, with "arousal" properties attributed to an increased release of dopamine in the CNS. Because other s...
journal_title：Medicine and science in sports and exercise
pub_type： 临床试验,杂志文章
doi：10.1249/01.mss.0000128146.12004.4f
更新日期：2004-06-01 00:00:00
abstract：:Recent research has demonstrated that intracellular signaling components associated with several proinflammatory cytokines have the potential to interact with signaling pathways that regulate anabolic processes in skeletal muscle. This presentation and the ensuing brief review are intended to present a selection of th...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e3181b07d12
更新日期：2010-01-01 00:00:00
abstract：PURPOSE:To describe physical activity (PA) levels by race/ethnicity, age, gender, and weight status in a representative sample of US youth. METHODS:Cross-sectional data from the 2003-2004 and 2005-2006 National Health and Nutrition Examination Survey were combined and analyzed. Youth aged 6-19 yr with at least four 10...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e3181e1fba9
更新日期：2010-12-01 00:00:00
abstract：:Although onset and maximal claudication pain are attained sooner as exercise intensity is increased, it is unclear whether dissipation of pain during recovery is altered. Thus, this study examined whether walking at gradually higher intensity would prolong the time needed for claudication pain to dissipate during reco...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：1993-08-01 00:00:00
abstract：PURPOSE:We evaluated the associations between accelerometer-estimated physical activity (PA) intensity and heart rate variability (HRV) and examined mediation of these associations by glycemic control indices and other cardiovascular disease risk factors. METHODS:Data were from 1668 participants (X[Combining Overline]...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0000000000002259
更新日期：2020-06-01 00:00:00
abstract：:The purpose of this study was to assess the relationship between the isometric and isokinetic peak torque (PT) (speed of movement 0, 60, and 180 degrees.s-1) and the peak torque acceleration energy (PTAE) and average power (AP) of multiple contractions (180 degrees.s-1) of the quadriceps and hamstrings in 38 patients ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：1989-06-01 00:00:00
abstract：:Ten eumenorrheic nonathletic women, aged 21-25, were studied on the 8th day following the LH peak in three consecutive cycles. Plasma level and metabolic clearance rate (MCR) of estradiol (E2) and progesterone (P) were measured before and during a 2-h continuous treadmill test at a speed corresponding to 70% of their ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：1992-07-01 00:00:00
abstract：OBJECTIVE:To determine the optimal crank length and crank-axle height for maximum power production during standing arm cranking ("grinding"). METHODS:Nine elite professional America's Cup grinders (age = 36 +/- 2 yr, body mass = 104 +/- 1 kg, body fat = 13% +/- 2%) performed eight maximal 6-s sprints on an adjustable ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e3181b46f3a
更新日期：2010-02-01 00:00:00
abstract：INTRODUCTION:This study examined the influence of a supplement matrix on the excretion pattern of nandrolone metabolites in response to ingestion of a trace amount of 19-norandrostenedione. METHODS:Ten male and nine female volunteers (mean ± SD: age = 26 ± 3 yr, height = 1.71 ± 0.09 m, body mass = 70.9 ± 13.2 kg) were...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/MSS.0b013e3181bf94d6
更新日期：2010-04-01 00:00:00
abstract：:This study characterizes exercise-induced lipid peroxidation during graded aerobic exercise in seven healthy men and women (36.4 +/- 3 yr). Levels of ethane and pentane in expired breath during cardiopulmonary exercise stress testing were measured at rest, lactic acidosis threshold (LAT), maximal exercise (VO2max), an...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1097/00005768-199708000-00008
更新日期：1997-08-01 00:00:00
abstract：PURPOSE:This study aimed to quantify the frequency, magnitude, and location of head impacts sustained by male and female collegiate ice hockey players during two seasons of play. METHODS:During two seasons, 88 collegiate athletes (51 females, 37 males) on two female and male National Collegiate Athletic Association va...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e31822b0ab4
更新日期：2012-02-01 00:00:00
abstract：PURPOSE:To investigate the maximal physiological responses between aquatic and land-based graded exercise tests in overweight women. METHODS:Twenty healthy, overweight (body mass index (BMI) > or = 25 kg.m(-2)), Caucasian women (mean +/- SD; age 48 +/- 7 yr, BMI 30 +/- 4 kg.m(-2)) completed a deep water running (DWR) ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e318164d0e0
更新日期：2008-05-01 00:00:00
abstract：PURPOSE:This study was conducted to determine the effect of high pedaling cadences on maximal cycling power output (W(max)). METHODS:Nine well-trained cyclists performed a continuous, incremental cycle-ergometer test to exhaustion (25 W increases every 3 min) either at 80, 100, or 120 rpm on three different occasions....
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/01.mss.0000218139.46166.ec
更新日期：2006-05-01 00:00:00
abstract：PURPOSE:To determine the relationships between moderate-to-vigorous physical activity (MVPA), vigorous physical activity (VPA), sedentary time, and obesity in children from 12 countries representing a wide range of human development. METHODS:The sample included 6539 children age 9-11 yr. Times in MVPA, VPA, and sedent...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,多中心研究
doi：10.1249/MSS.0000000000000649
更新日期：2015-10-01 00:00:00
abstract：PURPOSE:This study aimed to investigate longitudinal associations of objectively measured physical activity (PA) and sedentary behavior (SB) with body composition and physical fitness at a 12-month follow-up in healthy Swedish 4-yr-old children. METHODS:The data from the population-based MINISTOP trial were collected ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0000000000001313
更新日期：2017-10-01 00:00:00
abstract：PURPOSE:Postactivation potentiation (PAP), i.e., the increase in twitch torque following a maximal voluntary conditioning contraction, has been shown to depend on muscle contractile conditions (e.g., muscle length). Few studies, however, have investigated the extent of twitch PAP under dynamic conditions in human subje...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e318160ba54
更新日期：2008-04-01 00:00:00
abstract：PURPOSE:The objective of this study is to test the feasibility and impact of a 10-wk after-school exercise program for children with attention deficit hyperactivity disorder and/or disruptive behavior disorders living in an urban poor community. METHODS:Children were randomized to an exercise program (n = 19) or a com...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/MSS.0000000000000891
更新日期：2016-07-01 00:00:00
abstract：UNLABELLED:Hiking is a recreational activity shown to offer significant positive effects on the human body. However, walking downhill and external load carriage have both been shown to increase the risk of musculoskeletal pain and injury. The use of hiking poles has been demonstrated to be successful in reducing forces...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/01.mss.0000240328.31276.fc
更新日期：2007-01-01 00:00:00
abstract：INTRODUCTION:Inhaled beta2-agonists are important therapeutic agents for the treatment of exercise-induced asthma in athletes but are restricted by international antidoping regulations. PURPOSE:To investigate whether 18 mug of inhaled formoterol affects endurance performance during running at high altitudes until exha...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/01.mss.0000233801.46906.9b
更新日期：2006-12-01 00:00:00
abstract：PURPOSE:Neural adaptations to strength training have long been recognized, but knowledge of mechanisms remains incomplete. Using novel techniques and a design which limited experimental bias, this study examined if 4 wk of strength training alters voluntary activation and corticospinal transmission. METHODS:Twenty-one...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/MSS.0000000000001367
更新日期：2017-11-01 00:00:00
abstract：:Endocrine effects of self-administration of high doses of anabolic steroids and testosterone were investigated in five power athletes during 26 wk of training, and for the following 12-16 wk after drug withdrawal. After 26 wk of anabolic steroid and testosterone administration, serum testosterone concentrations had in...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：1985-06-01 00:00:00
abstract：PURPOSE:This study examined the direct, moderating, and indirect effects of dispositional optimism on the prediction of, and athletes' responses to, injury. METHODS:A 2-yr longitudinal design was conducted with a baseline sample of 694 asymptomatic participants (389 men, 305 women; mean ± SD age = 19.17 ± 1.69 yr), 10...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e31826ea8e3
更新日期：2013-02-01 00:00:00
abstract：:Natural killer (NK) cells are highly influenced by physical exercise. The possible important mechanisms behind exercise-induced changes in NK cell function are cytokines, hyperthermia, and stress hormones, including catecholamines, growth hormone, cortisol, and beta-endorphins. Infusion studies mimicking stress hormon...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,评审
doi：10.1249/00005768-199402000-00003
更新日期：1994-02-01 00:00:00
abstract：PURPOSE:To compare the cardiovascular reactivity response to mental challenge of aerobically trained and untrained preadolescent boys. METHODS:Heart rate (HR) and blood pressure, as well as stroke volume, total peripheral resistance, rate pressure product, and cardiac contractility response in 15 aerobically trained (...
journal_title：Medicine and science in sports and exercise
pub_type： 临床试验,杂志文章
doi：10.1249/01.MSS.0000078935.78895.8E
更新日期：2003-08-01 00:00:00
abstract：:The purposes of this investigation were to compare selected gait parameters characteristic of running without respiratory apparatus on a treadmill (NOR) with those displayed while wearing a mouthpiece-breathing valve apparatus (MP) and while wearing a respiratory face mask (MASK), and to compare the running economy (R...
journal_title：Medicine and science in sports and exercise
pub_type： 临床试验,杂志文章,随机对照试验
doi：
更新日期：1993-02-01 00:00:00
abstract：UNLABELLED:The extent of and the interactions between muscle strength, walking speed, postural control, and symptomatic fatigue in multiple sclerosis (MS) are not known, nor are the effects of bilateral strength asymmetries on these variables. PURPOSE:To quantify the magnitude of and the associations between bilateral...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e31817e32a3
更新日期：2008-10-01 00:00:00
abstract：PURPOSE:Investigate hemodynamic responses of resistance exercise (RE) with moderate load (i.e., international guidelines for RE of patients) versus RE with high load in patients with coronary artery disease (CAD). METHODS:Medically stable male (n = 11) and female patients (n = 4) treated with PCI or percutaneous coron...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/MSS.0000000000000811
更新日期：2016-04-01 00:00:00
abstract：:To determine the effects of anabolic steroids on myocardial structure, VO2max, and body composition, experienced age-matched male weight trainers (M age 26.5 yr) who either used (U) (N = 11) or did not use (NU) (N = 13) anabolic steroids were evaluated. Steroid users were tested while off cycle (U-OFF) for at least 8 ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：1993-11-01 00:00:00
abstract：PURPOSE:Ultraendurance exercise is steadily growing in popularity; however, the effect of increasingly prolonged durations of exercise on the vascular endothelium is unknown. The aim of this study was to characterize the effect of various ultramarathon running distances on vascular form and function. METHODS:We evalua...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0000000000002493
更新日期：2020-08-15 00:00:00
abstract：PURPOSE:Orienteering athletes must adapt to running on various surfaces, with biomechanics likely contributing to performance. Here, our aims were to identify the effect of athletic status and of surface on the running biomechanics of orienteers. METHODS:Seven elite and seven amateur male orienteers ran 20 m on road, ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0000000000000413
更新日期：2015-02-01 00:00:00
