ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Peliosis hepatis, an unusual condition characterized by blood-filled spaces within the hepatic parenchyma, usually occurs in a variety of chronic wasting diseases such as tuberculosis or malignancy. It has been described in patients undergoing therapy with anabolic steroids in pharmacologic doses over extended periods of time. To our knowledge it has not been described in athletes who utilize them for performance enhancement. This report concerns a 27-yr-old bodybuilder with peliosis hepatis, which developed after chronic intermittent use of anabolic steroids.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The purposes of this study were to: 1) compare shoulder range of motion and strength in professional baseball pitchers (N = 47) compared with age-matched controls (N = 16), and 2) examine the relationship of injury history to strength and range of motion. Based on injury history pitchers were categorized as: 1) none (N = 26), 2) injury requiring conservative intervention (N = 9), or 3) injury requiring surgical intervention (N = 12). Range of motion was measured for internal rotation (IROM) and external rotation (EROM). Eccentric strength was measured by hand-held dynamometer for internal rotation (IR), external rotation (ER), abduction (ABD), and supraspinatuss muscle (SUP) strength. Injury history had no effect on strength and range of motion. Dominant EROM was greater in pitchers, P < 0.0001, and controls, P < 0.05, with pitchers having greater EROM motion bilaterally, P < 0.0001. Pitchers were weaker in SUP on the dominant vs nondominant side, P < 0.0001, and on the dominant side for weight adjusted ER, ABD, P < 0.01, and SUP, P < 0.0001, compared with controls. In conclusion, dominance and pitching resulted in soft tissue adaptation. Pitchers displayed weakness in three of four tests by comparison with controls, suggesting that the demands of pitching are insufficient to produce eccentric strength gains and may in fact lead to weakness. Dominant-side SUP weakness in pitchers may reflect subclinical pathology or chronic fatigue.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Patellofemoral joint pain is one of the most common ailments associated with visits to sports medicine clinics and can be disabling, although conservative clinical treatment has a reportedly very high success rate. Patellofemoral joint pain is often associated with improper tracking of the patella within the femoral trochlear notch. Improper tracking of the patella can be associated with increased patellofemoral contact pressures that may be a mechanical stimulus underlying patellar cartilage degeneration. In those cases in which anatomic anomalies and trauma may be excluded as the basis for improper tracking, attention is directed toward possible disruptions to the central nervous system control and contractile potential of the knee joint extensor musculature that underlies proper patellofemoral mechanics. This paper presents a review of three seminal components related to the neuromechanics of patellofemoral function; patellofemoral tracking, patellofemoral contact pressures, and neuromotor control of patellofemoral agonists. It is the intent of the authors to illuminate areas requiring further basic and clinical research and provide a point of departure for this work.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Some contend that upper respiratory illness (URI) causes more disability among athletes than all other diseases combined. The purpose of this study was to describe the reporting behaviors, activity levels, and perceived physical performance levels of intercollegiate athletes with an URI. Respondents rated the severity of 14 cold symptoms and indicated to whom they reported their cold, and within how many days. Additionally, respondents were to indicate whether they self-treated their illness, whether they missed a practice or game due to the cold, and whether the cold affected their performance. The subjects for this study were 290 intercollegiate athletes (165 males, 125 females) in a large Midwestern conference. The instrument was administered at three regular intervals during the sport seasons. There was a total of 118 illness episodes. Respondents reported their colds to the athletic trainer (50.4%, N = 61), doctor/nurse (33%, N = 41), and/or coach (28.3%, N = 32). Athletes reported their cold symptoms earliest to the coach (2.45 d) or athletic trainer (2.71 d). The number of days prior to reporting to a doctor or nurse was longer (3.64 d). Of the illness episodes reported, 17.8% (N = 21) caused the athlete to miss a practice and 5.1% (N = 6) caused the athlete to miss a game. Athletes with an URI felt in some instances that their illness episode affected their performance. Cold symptoms of cough, fever, laryngitis, aching muscles/joints, and nasal discharge were significantly (P < 0.05) correlated with reporting behaviors, activity levels, and/or perceived physical performance. Possible implications for athlete participation and education are offered.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

It is well known that a linear relationship exists for submaximum exercise intensity and oxygen consumption. Most of the increase in oxygen consumption is by skeletal muscle mitochondria for the purpose of producing enough ATP to match the energy needs of the muscle. The control of mitochondrial ATP production in muscle when workload is varied is a complex process and remains a very active area of research. Thus, the purpose of this symposium is to discuss the factors involved in the coupling between increases in work and increased oxygen consumption by muscle. The program will begin with a consideration of the challenges faced by skeletal muscle when attempting to meet its energy demands and the intracellular strategies that have evolved to optimize energy delivery. Next the major control theories for mitochondrial respiration will be discussed. Finally, experiments will be presented that are designed to determine which of these theories are best suited for specific skeletal muscle fiber types. It is hoped that the information presented will increase our awareness of different energy supply-demand strategies among fiber types and how supply-demand strategies are optimized by endurance training.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The creatine kinase reaction is traditionally viewed as providing an energy reserve in muscle. However, the physiological importance of this reaction (and the analogous invertebrate reaction catalyzed by arginine kinase) is better understood when viewed as providing metabolic capacitance. This capacitance allows reduction of peak rates of ATP synthesis in cells that alternate between periods of high and low energy consumption. Furthermore, the capacitance allows repayment of energy “debt” that is incurred during periods of high energy demand to occur during periods of low rates of energy consumption. The creatine kinase reaction provides facilitated diffusion of ATP and ADP, which leads to spatial buffering in addition to temporal buffering. Data are presented which suggest that the existence of the creatine kinase reaction allows muscle cells to maintain reduced mitochondrial volume, support larger diameter fibers, and express faster isoforms of myosin. These data lead to speculation that there may be a coupling in the expression of metabolic and contractile proteins.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Mitochondrial oxidative phosphorylation in vivo is dependent on the degree of reduction of the intramitochondrial reducing power ([NADH]/[NAD+], cytoplasmic energy state ([ATP]-/[ADP][Pi]) and intracellular oxygen pressure. Each parameter is independently regulated, and increased reducing power by activating the mitochondrial dehydrogenases allows higher energy state at a given rate of ATP synthesis or a higher rate of ATP synthesis at a given energy state. The mitochondrial respiratory rate is determined by demand, i.e., the rate of ATP utilization by the cell, while the cellular energy state at that demand level is determined by supply, i.e., activity of the dehydrogenases expressed as [NADH]/[NAD+] and of cytoplasmic oxygen pressure.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Ca2+ions activate four mitochondrial enzymes (viz. glycerol 3-phosphate dehydrogenase, pyruvate dehydrogenase phosphatase, NAD-isocitrate dehydrogenase and 2-oxoglutarate dehydrogenase) that are involved in substrate de-hydrogenation and production of NADH as a substrate for oxidative phosphorylation. As cytosol Ca2+, and presumably mitochondrial Ca2+, concentrations are raised during muscle contraction, this is thought to provide a mechanism whereby the activity of oxidative phosphorylation is raised in working muscle without the necessity of unacceptably large decreases in adenine nucleotide phosphorylation potential. These ideas are explored in this article, with particular reference to the activation of pyruvate dehydrogenase in cardiac and skeletal muscle preparations and its dependence upon both cytosolic and intramitochondrial Ca2+ion concentrations.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

We examined the relationships between PCr and Pi vs oxygen consumption or twitch rate during stimulation of rat muscle in situ and of perfused cat biceps and soleus muscles. In fast-twitch muscles such as rat gastrocnemius and cat biceps, we found a linear relationship between PCr and oxygen consumption. This result favors thermodynamic regulation of oxygen consumption by cytoplasmic phosphorylation potential rather than kinetic regulation by ADP. PCr changes during stimulation of rat muscle depleted of total creatine or adenine nucleotide were also not consistent with simple kinetic regulation by ADP. In cat soleus (slow-twitch) muscle, the observation of nonexponential PCr changes during stimulation suggested more complicated regulation, possibly involving changes in mitochondrial redox potential.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID