The purpose of this research was to evaluate the effects of a long-term
static stretching program on flexibility and spinal reflexes in the
human soleus muscle. Day-to-day reliability over two days of H-reflex gain
(Hslp/Mslp) and pre-synaptic inhibition of spinal reflexes in the human
soleus was measured in an initial...
Skeletal muscles provide several functions, including, yet not limited to, voluntary body movement and locomotion, posture and body position, and soft tissue support. Skeletal muscles also play a role in metabolism, requiring energy to facilitate contraction. Each skeletal muscle serves a different purpose despite seeming to perform the same task....
Space flight results in loss of mass and function in skeletal
muscle. Data from manned flights and animal biosatellites give
evidence of possible changes in neuromuscular interactions.
Components at the neuromuscular junction are a potential site of
action for this space-induced muscle atrophy. We examined the
nicotinic acetylcholine receptor population...
During explosive movements and potentially injurious situations the ability to rapidly generate torque is critical. Previous research has suggested different phases of rate of torque development (RTD) are differentiately controlled. However, the extent to which supraspinal and spinal mechanisms predict RTD at different time intervals is unknown. RTD of the...
The goals of this research were to a) characterize the protein-function relationships of skeletal muscle single fibers from the mouse hindlimb b) examine mouse-strain related differences in myosin heavy chain composition (MHC) and single fiber contractile function, and c) quantify changes in fiber size and contractile function in response to...
Activity‐related knee joint dysfunction is more prevalent in females than males. One explanation
for the discrepancy is differences in movement patterns between the sexes. However the underlying
mechanisms responsible for these differences remain unidentified. This study tested spinal motor
control mechanisms influencing motor neuron pool output and subsequent muscle activation...
The purpose of this study was to determine the effects of homosynaptic depression (HD) on spectral properties of the soleus (SOL) H-reflex. Paired stimulations, separated by 100 ms, were used to elicit an unconditioned and conditioned H-reflex in the SOL muscle of 20 participants during quiet standing. Wavelet and principal component...
Calcium activated proteases, or calpains, are activated in cardiac muscles under conditions of ischemia/reperfusion and hypoxia. Their activity in skeletal muscle under similar conditions is poorly understood. We tested the hypothesis that hypoxia elevates calpain-mediated proteolysis in isolated glycolytic (extensor digitorum longus, EDL) and oxidative (soleus, SOL) mouse muscles studied...
Context: Static stretching is commonly used during the treatment and rehabilitation of orthopedic injuries to increase joint range of motion (ROM) and muscle flexibility. Understanding the physiological adaptations that occur in the neuromuscular system as a result of long-term stretching may provide insight into the mechanisms responsible for changes in...
Although research supports the use of whole-body vibration (WBV) to improve neuromuscular performance, the mechanisms for these improvements remain unclear. The purpose of this study was to identify the effect of WBV on the spectral properties of electrically evoked H-reflex recordings in the soleus (SOL) muscle. The H-reflex recordings were...
The purpose of this study was to determine the effects of plyometric training on both spinal and supraspinal motor control as well as the rate of torque development (RTD) in healthy active females. Thirty-one subjects were recruited to participate in the study and participated in either the training or control...
Recently, changes in human performance following whole-body vibration (WBV) training have been attributed to enhanced neuromuscular function. However, the exact neural and muscular mechanisms responsible for these changes remain less understood. The purpose of this study was to evaluate the acute and chronic effects of whole body vibration on the...
Female athletes exhibit three- to six-fold greater incidence of noncontact anterior cruciate ligament (ACL) injury relative to their male counterparts. The increased risk appears to stem from interactions between several risk factors, that can roughly be categorized as anatomic, biomechanical, hormonal, and neuromuscular. Neuromuscular risk factors have recently gained a...
Long-term functional changes after whole-body vibration (WBV) training have been attributed to adaptations in the neuromuscular system. The present study examined the effect of four weeks of WBV training on muscle function outcome variables [rate of force development (RFD), electromechanical delay (EMD)], and spinal control mechanisms (pre-synaptic inhibition). Forty young...
Hoffman-reflex (H-reflex) recruitment curves. Smoothed and interpolated recruitment curves from 38
participants were used for analysis. Standard methods were used to calculate three discrete variables
(i.e., H[subscript max]/M[subscript max] ratio, H[subscript th], H[subscript slp]). FPCA was then used to extract principal component functions (PCFs)
from the processed recruitment curves. PCF...
After a joint injury, arthrogenic muscle inhibition (AMI) leads to decreased neuromuscular control and strength, as neural inhibition prevents volitional activation of the entire motor neuron pool. Traditional rehabilitation techniques such as strength training are unable to effectively reduce AMI and there is a need to identify interventions that can...
Despite years of research, females continue to have a higher incidence of non-contact ACL injuries. One of the major findings of this research is that males and females perform certain tasks, such as, cutting, landing, and single-leg squatting, differently. In particular, females tend to move the knee into a more...
Relationships between myosin heavy chain (MHC) isoform content and
eccentric-induced damage were investigated in chemically skinned muscle fiber
segments. Fibers were subjected to an eccentric contraction standardized for strain
magnitude (0.25 fiber length) and velocity (0.50 maximal shortening velocity).
Fiber MHC isoform content was identified by SDS-PAGE. Pre- to post-eccentric...
The nervous system has an integral role in rapid torque production of the lower extremity, which is often necessary for proper motor response to a dynamic environment. The nervous system is complex with numerous pathways, including spinal motor control networks, which influence the ability to move. However, few studies have...
Mechanisms of motor control and function are interesting to those from the medical, athletic training and sports performance professions primarily during the development of conditioning and rehabilitation programs. The aim of this study was to assess spinal control mechanisms in two groups of explosively trained, female athletes from a NCAA...
Muscle weakness and fatigue are debilitating symptoms of multiple sclerosis (MS). Approximately 50% of muscle weakness and fatigue have been attributed to deficits within the peripheral nervous system, specifically mechanisms residing in the muscle. The goals of this study were to identify the cellular mechanisms of contraction within the muscle...
The ability to quickly generate torque of the triple extensors is critical during rapid movements, especially when there is not enough time to reach peak torque. Rate of torque development (RTD), which is the rate of rise of the torque-time curve, is a commonly used measure of rapid torque generation....
A backward fall is a major cause of hip fractures. Hip fractures have the potential to increase the mortality rate of older adults. Thus, the prevention of backward falls by older adults is a critical subject to be studied. Specifically, it remains unknown what effect aging-related losses in muscle strength...
We hypothesized that calpain activity is elevated in response to muscle damage. To test this hypothesis, we examined the degradation of α-fodrin into its 150 and 145 kDa fragments following either 20 eccentric or isometric contractions. In addition, experiments were performed in the presence or absence of E-64-d, a calpain...
Previous attempts to understand the factors affecting the energetic cost of locomotion have found a direct link between the energetic cost and the mechanical work done during periods when the limb is in contact with the ground. However, when the limb is not in contact with the ground during the...
Rapid unloading and a peak in power output of the ankle joint have been widely
observed during push-off in human walking. Model based studies hypothesize that this
push-off to causes redirection of the body center of mass just before touch-down of the
leading leg. Other research suggests, that work done...
Tibial stress fractures are common in runners. However, it is unclear what factors are associated with tibial stress fractures. This study aimed to investigate 1) magnitudes of bone contact forces occurring while running 2) whether or not repeated application of running loads is sufficient to explain tibial stress fractures and...
BACKGROUND: Glucose homeostasis is distorted by defects of the PI3K/AKT and AMPK pathways in insulin-sensitive tissues, allowing the accumulation of glucose in the blood. The purpose of this study was to assess the effects and mechanisms by which ethanol extract of Caulerpa lentillifera (CLE) regulates glucose metabolism in C57BL/KsJ-db/db (db/db)...
The lack of hamstring muscle group flexibility has previously been associated with a higher incidence of hamstring strains among athletes. Several stretching methods have been shown to increase hip joint range of motion (ROM); however, identification of an optimal stretching method has proven difficult. The purpose of this study was...
The increase in obesity rates in both children and adults in the United States may be a result of impaired or dysregulation of fat metabolism. Long chain acyl-CoA synthetases (ACSLs) may be key regulators of skeletal muscle cell fat metabolism, including fat oxidation and storage. The purpose of the study...
Resistance training is widely prescribed for rehabilitation of injuries and as a method to improve athletic performance. It is accepted that resistance training increases the maximal force production of whole muscle and it has been suggested that the velocity of shortening can increase as well. However, little is known about...
Twenty-seven male college football linemen from the Oregon State
University football team served as subjects for the study to determine
which variables in strength and power would be best suited for use in
regression analysis with tibial nerve conduction velocity (TNCV). The
purpose of the investigation was to determine whether...
The first goal of this study was to evaluate the roles of different intracellular
proteolytic systems in accelerated skeletal muscle protein degradation. Total,
myofibrillar and non-myofibrillar proteolysis were determined in cultured L8/CID
muscle cells. Calpain proteolysis was assessed by over-expressed calpastatin inhibitory
domain (CD). Lysosomal proteolysis was determined in the...
Despite the advances in surgery, physical therapy, and pharmaceutical agents, muscle
dysfunction (i.e., atrophy and weakness) continues to impair recovery from an anterior
cruciate ligament (ACL) injury and surgery. Ischemia-reperfusion injury during surgery
and the subsequent limb disuse are two events experienced by patients having ACL
surgery. Oxidative stress and...
Skeletal muscle proteins are the largest amino acid pool in animal body and are continuously degraded and resynthesized. Dozens of factors have been shown to influence the balance between synthesis and degradation and thereby regulate muscle growth and function. It is now know that one of the major regulatory bases...
Little, if any, quantifications have been made on the contribution of the vertebral column during jumping in quadrupedal mammals. Previous studies of jumpers have focused on the morphological and physiological specializations of the hindlimbs. In this study, such specialization was measured during the supramaximal jumps of the Pacific jumping mouse...
Introduction: Recent reports in exercise related bone research have shown increased bone mineral content (BMC) at the femoral neck for prepubescent children participating in exercise programs consisting of repeated drop landings from a height of 61 cm. Increases in BMC from this type of exercise are believed to be the...
Background: While males generally outperform females in athletic tasks, the underlying mechanisms for this difference remain unclear. Explosive neuromuscular performance of the triple extensors, often investigated via rate of torque development (RTD), is crucial for athletic tasks such as a vertical jump. Purpose: To assess sex differences in rapid torque...
Biorhythm theory proponents believe that humans have
a 23-day physical cycle, a 28-day emotional cycle, and a
33-day intellectual cycle. According to biorhythm theories
a person in the positive portion of any single cycle, the performance potential is enhanced for those tasks related to
that particular rhythm. When each cycle...
Eight male college students served as subjects in an investigation
to establish a procedural model for research of individual motor
units during sustained isometric contractions. Teca TE-4 electromyograph
system with needle electrode provided electrical potential
recordings from active muscle fibers in the right biceps. Various
experimental procedures were tested to...
Two concurrent trials were conducted to examine genetic and
environmental influences on growth rate, carcass fatness
and muscle fiber type proportions. Trial 1 compared
Polypay and Coopworth x Polypay male lambs either left
intact or castrated early, mid or late in growth. Trial
two compared Hampshire sired lambs (females, early...
Falls in older adults are an important concern due to the potential injuries associated with falling. Decreases in muscle strength as a result of natural aging could impair the ability of older adults to prevent either a backward or forward fall. Two musculoskeletal models were used to predict the effect...
Background: The capability of an individual to produce force rapidly is important for performance of sporting activities and to stabilize a joint to protect against injury. Rate of torque development (RTD) and contractile impulse (CI) may be more effective than peak torque in assessing rapid torque production. The relationship between...
Purpose: To investigate the influences of RTD on biomechanical factors upon landing. Methods: A nine camera motion capture system (Vicon, Inc.) was used with standard retroreflective marker set (27 static, 23 dynamic) to capture lower limb kinematics of 40 healthy female subjects during double leg jump landing (DL) and single-leg...
The presence of an increased accumulation of intraabdominal fat (IAF) has been linked to dyslipidemia, hyperinsulinemia, and hyperglycemia, which precede the development of type 2 diabetes and coronary artery disease (CAD). It has been shown that IAF begins depostition during childhood. Human studies suggest that regular endurance exercise, that does...
Purpose: The purpose of this study was to determine the effectiveness, if any, of ten weeks of motor psychophysics training on the
development of dynamic muscular strength (as measured by the bench
press and squat) in male college athletes and non-athletes.
Procedures: This study was conducted during the first (spring)...
There are at least fifteen types of upper extremity tendon transfer procedures for combined peripheral nerve injuries that involve re-routing a single donor muscle to multiple recipient tendons. As a result, force and movement across finger joints become coupled, resulting in limited grasping abilities. Quantification and modeling of the donor...
Although female athletes are at greater risk of non-contact knee injuries than men, the factors that contribute to these injuries are not well understood. One important question is whether intense exercise influences the risk of knee injury, both acutely
and over the following days. The purpose of this study was...
Skeletal muscle mitochondria are highly plastic organelles, integral to whole-body health. High-fat diet (HFD) and exercise remodel the skeletal muscle mitochondria. Whereby, altered skeletal muscle mitochondrial function is linked to decreased skeletal muscle insulin sensitivity which can be reversed by exercise. However, the mechanisms that contribute to skeletal muscle remodeling...
Altered skeletal muscle fat metabolism is linked to changes in skeletal muscle insulin sensitivity. Whereby the accumulation of bioactive signaling lipids (i.e., diacylglycerols and ceramides) within skeletal muscle are negatively associated with insulin sensitivity and the exercise-induced changes to fatty acid trafficking are related to improved skeletal muscle insulin action....
Objective: To determine the effectiveness of moderate pre-exercise warm-up, static stretching, or a combination of both on muscular force production and hamstring extensibility of the lower extremity. Design and Setting: This experiment was a counterbalanced repeated measures design of four treatment conditions. Subjects participated in warm-up, static stretching, combined warm-up...
Objectives: To evaluate postural control in individuals with functional ankle instability using static, dynamic, and clinical balance tests. Also, to examine the relationships between the performances in each of these tests. Design: Postural control was evaluated with a single leg balance test, a balance test involving movement, and the star...
Alterations in gait patterns are commonly observed in individuals with transtibial amputation (TTA) who use a prosthesis. Current commercially available ankle-foot prostheses (AFP) offer very little range of motion (ROM) at the ankle joint. Previous researchers have hypothesized that lack of ankle ROM significantly contributes to alterations in TTA gait...
Menstrual dysfunction (MD), possibly due to lower energy availability (EA), is prevalent in active women and associated with unfavorable heath consequences. PURPOSE: To determine if EA improvements in endurance-trained women, using a daily Carbohydrate-Protein supplement (CHO-PRO), will restore menstrual function and improve musculoskeletal health. METHODS: Athletes with MD (ExMD; n=8;...
Decline in cardiac pump function is a hallmark of aging where mitochondrial decay is an important underlying cause. Although certainly multifactorial in nature, both dysfunction of the machinery involved in the chemiosmotic process of energy transduction and lower capacity to maintain fatty acid-driven respiration are identified as intrinsic factors of...
The first goal of this study was to understand the role of calpains in skeletal muscle
protein degradation in cultured cells. We have developed a genetic approach to inhibit
endogenous calpain activity through over-expressing dominant negative m-calpain (DN),
antisense m-calpain (AS) and calpastatin inhibitory domain (CID). We observed that,
under...
Although the incidence of non-contact anterior cruciate ligament (ACL) injuries is greater among women than men athletes, the factors that contribute to this greater risk of injury are not well understood. One relevant question is whether decision making during landing influences the biomechanical and neuromuscular factors thought to contribute to...
Forty-five young adult males were given 30 trials of Isometric
knee extension and 30 trials of isometric knee flexion. Each trial
consisted of a maximum of three second exertion followed by a 10
second intertrial rest interval. Subjects were ranked on the basis
of the mean of the first three...
Glucocorticoids are growth-inhibiting steroids. They have been reported to reduce
muscle growth by reducing protein synthesis. However, their actions on muscle protein
degradation remain equivocal. Glucocorticoids have been reported to transiently increase
muscle protein degradation, to not affect this process and to reduce muscle protein
degradation. Reasons for these conflicting...
Forty-five subjects were given 30 trials of isometric elbow flexion
and 30 trials of elbow extension. Each trial consisted of maximum
exertion followed by a short rest in 10 second cycles. Subjects were
ranked on the basis of the addition of the median flexion and extension
scores and were divided...
A static analysis of quadruped biomechanics, combined with
observations of longitudinal postural movement, has revealed important functional attributes of the postural control system. Since
posture is an outward expression of central nervous system (CNS)
behavior, these results may contribute to an understanding of integrative
functions of the CNS.
Beginning from...
Five lines of turkeys with wide variation in body size, reciprocal
crosses between large and small lines, and backcrosses to the
large parent line were studied to determine the effect of body size
and crossbreeding on growth rate, conformation, feed consumption,
organ size, and other physiological traits.
Selection was made...
Hip fractures have high mortality and morbidity rates after incidence, with osteoporosis being a major risk factor due to the loss of bone mineral density (BMD). Lower-body resistance exercises, such as squats, can provide sufficient loading on the hip to induce osteogenic effects. However, this loading may depend on how...
The purpose of this investigation was to determine the
effectiveness of a 6-week strength training program consisting of
squat and plyometric exercises on vertical power jump performance,
static and dynamic muscular strength, and muscular power production
in college age adults. Fifteen male and two female college students
in an advanced...
PURPOSE: The purpose of this research was to quantify the effects of a warm-up with static or dynamic stretching on countermovement jump height, reaction time, muscle onsets for tibialis anterior (TA) and vastus lateralis (VL), and low back/ hamstring flexibility.
METHODS: Twenty one recreationally-active males (24.4 ± 4.5 yrs), recruited...
Skeletal muscle, the largest organ in the body in mass, is composed by 600 specialized muscles in humans with unique biochemical, physiological and metabolic identities. Skeletal muscles control body movement, locomotion, and nutrient balance. Muscle formation requires precisely orchestrated environmental signals and regulatory gene networks in time and space. Gene...
The investigation of force attenuation and performance strategies to respond to changing mechanical constraints helps prevent injury as well as facilitates beneficial insight to provide appropriate instruction to athletes and students. The primary purpose of the study was to assess within subject variability of landing strategies when responding to additional...
Calcium channel blockers (CCB) was studied extensively in cardiology for their tissue
protective effect following myocardial infarction; we hypothesized that administration of
a CCB would interfere with the processes that result in exercise-induced muscle damage
(EIMD) and delayed onset muscle soreness. To investigate the effects of a CCB on a...
Under researched somatosensory contributions to postural stability, in addition to high incident rates of foot injury in the physically active population, lead to two investigative studies. An initial research study compared variables of two postural stability assessment devices to determine reliability of outcome measures and commonality of outcome measures to...
The influence of alfalfa fiber level 28, 54 and 74% in diets on
the proximate compositions, pH and water-holding capacity of raw and
cooked rabbit meat were investigated.
Preslaughter live weight, percent dress weight and percent
abdominal fat of rabbits fed 54% alfalfa fiber diet were
significantly higher and total...
Twenty-six Holstein and 18 Jersey multiparous cows in a randomized block design were assigned by calving date and breed to a non-anionic prepartum diet (CTRL) or a treatment diet containing a commercial anionic salt supplement (Animate®). Control and treatment diets were formulated to a dietary anion-cation difference (DCAD) of 21.3...
The purpose of this study was to evaluate the effectiveness
of a one-hour in-service nutrition education
workshop for high school coaches in Corvallis, Eugene and
Salem, Oregon. The objectives were to determine: 1. if
the workshop can make positive changes in nutrition knowledge;
2. which type of participant benefits most...