Barry M. Prior's research while affiliated with Mercer University and other places

Publications (56)

Article
This study examined the capacity of collateral dependent blood flow induced by a prolonged treadmill training program, as compared to a low collateral resistance model created by femoral artery to vein (A-V) shunt. Sprague-Dawley rats, with bilateral femoral artery occlusion were confined to cage activity (Sed, n=9) or trained by daily treadmill ex...
Article
Peripheral arterial insufficiency is a progressive degenerative disease associated with an increased morbidity and mortality. It decreases exercise tolerance and often presents with symptoms of intermittent claudication. Enhanced physical activity is one of the most effective means of improving the life of affected patients. While this occurs for a...
Article
Evidence from experimental animal studies indicate that ACE inhibition expands collateral blood flow both in ischemic hearts and peripheral limbs. The present study evaluates whether ACE inhibitor induces collateral blood flow expansion and change of angiogenic gene expression profile in collateral arteries during remodeling. Male Sprague-Dawley ra...
Article
Full-text available
Skinfold (SKF) equations exist to predict percent body fat (%BF) in athletes; however, none have been derived from multicomponent model reference measures. To develop and cross-validate a %BF prediction equation based on SKF in athletes using a four-component model as the reference measure. Subjects were 132 collegiate athletes (20.7 +/- 2.0 yr; 78...
Article
The purpose of this investigation was to determine whether whole body composition could be estimated in tall individuals using summed measures from two partial DXA scans. Using a pencil-beam DXA, a convenience sample of young individuals (N = 19) were scanned three times. Two partial scans of the upper and lower body were combined to predict bone a...
Article
Both collateral vessel enlargement (arteriogenesis) and capillary growth (angiogenesis) in skeletal muscle occur in response to exercise training. Vascular endothelial growth factor (VEGF) is implicated in both processes. Thus we examined the effect of a VEGF receptor (VEGF-R) inhibitor (ZD4190, AstraZeneca) on collateral-dependent blood flow in vi...
Article
The objectives of this study were to assess the time course of enlargement and gene expression of a collateral vessel that enlarges following occlusion of the femoral artery and to relate these responses to the increases in collateral-dependent blood flow to the calf muscles in vivo. We employed exercise training to stimulate collateral vessel deve...
Article
The aim of this study was to monitor the effects of topical heat and/or static stretch treatments on the recovery of muscle damage by eccentric exercise. For this purpose, 32 untrained male subjects performed intense eccentric knee extension exercise, followed by 2 weeks of treatment (heat, stretch, heat plus stretch) or no treatment (control, n=8/...
Article
Exercise and muscle contractions create a powerful stimulus for structural remodeling of the vasculature. An increase in flow velocity through a vessel increases shear stress, a major stimulus for enlargement of conduit vessels. This leads to an endothelial-dependent, nitric oxide-dependent enlargement of the vessel. Increased flow within muscle, i...
Article
Angiogenesis occurs in skeletal muscle in response to exercise training. To gain insight into the regulation of this process, we evaluated the mRNA expression of factors implicated in angiogenesis over the course of a training program. We studied sedentary control (n = 17) rats and both sedentary (n = 18) and exercise-trained (n = 48) rats with bil...
Article
Arteriogenesis is an important process for adapting the pre-existing circuit of vessels into functional collateral conduits for delivery of oxygen enriched blood to tissue distal to occlusion of a large, peripheral conduit artery. Recent evidence has shown that arteriogenesis is regulated by nitric oxide (NO), angiogenic factors and shear stress. N...
Article
Exercise produces a powerful angiogenic stimulus within the active muscle that leads to a functionally important increase in capillarity. Further, exercise can increase flow capacity by enlarging the caliber of arterial supply vessels. These adaptations are achieved by the processes of angiogenesis and arteriogenesis, respectively.
Article
This study tested the hypothesis that fatigue of a single member of musculus quadriceps femoris (QF) would alter use of the other three muscles during knee extension exercise (KEE). Six men performed KEE with the left QF at a load equal to 50% of the 4 x 10 repetitions maximum. Subsequently, electromyostimulation (EMS), intended to stimulate and fa...
Article
Differences in the mineral fraction of the fat-free mass (M(FFM)) and in the density of the FFM (D(FFM)) are often inferred from measures of bone mineral content (BMC) or bone mineral density (BMD). We studied the relation of BMC and BMD to the M(FFM) and D(FFM) in a heterogeneous sample of 216 young men (n = 115) and women (n = 101), which include...
Article
Full-text available
Differences in the mineral fraction of the fat-free mass (M FFM ) and in the density of the FFM (D FFM ) are often inferred from measures of bone mineral content (BMC) or bone mineral density (BMD). We studied the relation of BMC and BMD to the M FFM and D FFM in a heterogeneous sample of 216 young men ( n = 115) and women ( n = 101), which include...
Article
We hypothesized that activation of the quadriceps femoris muscle group during eccentric exercise is related to the increase in magnitude of several markers of muscle injury that developed during the next week. Fourteen male subjects performed six to eight sets of five to ten repetitions of single-leg eccentric-only seated knee extension exercise. M...
Article
Previous studies suggest that the activity-induced increase in 1H-NMR transverse relaxation time (T2) observed in mammalian skeletal muscles is related to an osmotic effect of intracellular metabolite accumulation. This hypothesis was tested by comparing T2 (measured by 1H-NMR imaging at 4.7 T) and metabolite changes (measured by 31P-NMR spectrosco...
Article
Full-text available
The purpose of this study was to use estimates of body composition from a four-component model to determine whether the density of the fat-free mass (D(FFM)) is affected by muscularity or musculoskeletal development in a heterogenous group of athletes and nonathletes. Measures of body density by hydrostatic weighing, body water by deuterium dilutio...
Article
Full-text available
The increase in nuclear magnetic resonance transverse relaxation time (T(2)) of muscle water measured by magnetic resonance imaging after exercise has been correlated with work rate in human subjects. This study compared the T(2) increase in thigh muscles of trained (cycling VO(2 max) = 54.4 +/- 2.7 ml O(2). kg(-1). min(-1), mean +/- SE, n = 8, 4 f...
Article
Full-text available
This study examined the relationships between muscle fiber type, metabolism, and blood flow vs. the increase in skeletal muscle (1)H-NMR transverse relaxation time (T2) after stimulation. Triceps surae muscles of anesthetized rats were stimulated in situ at 1-10 Hz for 6 min, and T2 was calculated from (1)H-NMR images acquired at 4.7 T immediately...
Article
Full-text available
Introduction Previous studies show that transient increases in limb blood flow occur after single muscle contractions (1), and one preliminary report (2) suggests that this transient hyperemia is associated with a BOLD (Blood-Oxygenation-Level-Dependent) effect in muscle. While BOLD effects have been reported in skeletal muscle during ischemia and...
Article
Full-text available
Muscle functional magnetic resonance imaging (MRI) is used to compare the relative involvement of different muscles recruited during exercise. The method relies on the activity-induced increase in the nuclear magnetic resonance transverse relaxation time (T2) of muscle water, which is caused by osmotically driven shifts of fluid into the myofibrill...
Article
Full-text available
Increases in skeletal muscle (1)H-NMR transverse relaxation time (T2) observed by magnetic resonance imaging have been used to map whole muscle activity during exercise. Some studies further suggest that intramuscular variations in T2 after exercise can be used to map activity on a pixel-by-pixel basis by defining an active T2 threshold and countin...
Article
Full-text available
The purposes of this study were, first, to clarify the long-term pattern of T2 relaxation times and muscle volume changes in human skeletal muscle after intense eccentric exercise and, second, to determine whether the T2 response exhibits an adaptation to repeated bouts. Six young adult men performed two bouts of eccentric biceps curls (5 sets of 1...
Article
The purposes of this study were, first, to clarify the long-term pattern of T2 relaxation times and muscle volume changes in human skeletal muscle after intense eccentric exercise and, second, to determine whether the T2 response exhibits an adaptation to repeated bouts. Six young adult men performed two bouts of eccentric biceps curls (5 sets of 1...
Article
Full-text available
To provide more comprehensive information on the extent and pattern of muscle activation during running, we determined lower extremity muscle activation by using exercise-induced contrast shifts in magnetic resonance (MR) images during horizontal and uphill high-intensity (115% of peak oxygen uptake) running to exhaustion (2.0-3.9 min) in 12 young...
Article
Full-text available
We validated whole body composition estimates from dual-energy X-ray absorptiometry (DEXA) against estimates from a four-component model to determine whether accuracy is affected by gender, race, athletic status, or musculoskeletal development in young adults. Measurements of body density by hydrostatic weighing, body water by deuterium dilution, a...
Article
Anaerobic capacity as measured by the maximal or peak oxygen deficit is greater during uphill than during horizontal running. The objective of this study was to determine whether the greater peak oxygen deficit determined during uphill compared with horizontal running is related to greater muscle volume or mass activated in the lower extremity. The...
Article
Full-text available
Sloniger, Mark A., Kirk J. Cureton, Barry M. Prior, and Ellen M. Evans. Anaerobic capacity and muscle activation during horizontal and uphill running. J. Appl. Physiol. 83(1): 262–269, 1997.—Anaerobic capacity as measured by the maximal or peak oxygen deficit is greater during uphill than during horizontal running. The objective of this study was t...
Article
Full-text available
We compared the effects of concentric (Con) and eccentric (Ecc) isokinetic training on quadriceps muscle strength, cross-sectional area, and neural activation. Women (age 20.0 +/- 0.5 yr) randomly assigned to Con training (CTG; n = 16), Ecc training (ETG; n = 19), and control (CG; n = 19) groups were tested before and after 10 wk of unilateral Con...
Article
Full-text available
The purpose of this study was to determine whether the assumed density and composition of the fat-free mass (FFM) and estimates of percent fat (%Fat) from body density by use of the Siri equation (%Fatd) are valid in weight trainers with high musculoskeletal development. Measures of body density by underwater weighing (Db), body water by deuterium...
Article
During constant-rate high-intensity (CRHI) exercise lasting longer than 3 min, VO2 has been reported to exceed VO2max measured with a traditional graded exercise test (GXT). This could be because VO2max was not achieved on the GXT or because the factors responsible for the slow-component rise in VO2 alter VO2max. The objective of this study was to...
Article
Full-text available
1. Histological evidence suggests that the force deficit associated with eccentric contraction-induced muscle injury is due to structural damage to contractile elements within the muscle fibre. Alternatively, the force deficit could be explained by an inability to activate the contractile proteins. It was the objective of this study to investigate...
Article
Full-text available
1. The initiation of exercise-induced muscle injury is thought to be the result of high tensile stresses produced in the muscle during eccentric contractions. Materials science theory suggests that high tensile stresses could initiate the injury during the first eccentric contraction (normal stress theory) or after multiple eccentric contractions (...
Article
Full-text available
It is well-known that the T2 of muscle water increases during contractile activity (1). This change has been attributed both to intracellular acidification, and to accumulation of Pi, lactate, and other osmolites, which could alter the volume or exchange between intracellular water compartments with varying intrinsic relaxation rates. The purpose o...

Citations

... Muscle damage was determined to have occurred if the primary measure of T 2 MR imaging and at least one of the other two safety measures were noted to be positive for indicating damage. T 2 MRI: T 2 weighted MRI has been extensively used as a construct of muscle damage and inflammation/edema, when performed 24-48 hours following exercise [9][10][11][12][13][14][15][16] . It detects acute muscle damage in vivo and has been correlated with histological markers to become a non-invasive, sensitive marker of muscle injury [17][18][19][20][21] . ...
... The main mechanism that could explain an increase in the . VO 2 while running uphill is likely the higher muscular mass involved in this condition, especially for the vastus, soleus, gluteus, biceps femoris and gastrocnemius muscles [31,32,[47][48][49]. In addition, uphill running over a 15% gradient eliminates the bouncing mechanism and the use of elastic energy, which is helpful for displacement [22,50,51]. ...
... A second possibility is that perhaps the training made the whole muscle more homogenous in terms of fiber type and/or metabolic profile. It has been shown that drastic differences in fiber type, such as those that occur in different rat hind-limb muscles, can influence the magnitude of T2 response (29). Theoretically then, training-induced fiber type changes, such as the rapid reduction of IIb fibers often observed following resistance training (30), could result in a less variable T2 distribution. ...
... To test this and provide an indication of the level of local oxygenation of the TA muscle in each protocol, a subset of three participants completed an additional repetition of the three protocols using near infrared spectroscopy (Oxiplex TS, Model 92505; ISS, Champaign, Illinois, USA). The probe was secured over the muscle belly of the TA following published guidelines (Meyer et al. 2001). Results showed a reduction in [HbO] of 44% and increase in [Hb] of $48% during the BFO prox protocol at 100% of TTF. ...
... Thirty-one subjects were taller than the scanning region of the DXA instrument. Bone ash and BMD for these subjects were estimated from the summed values from two separate scans (upper and lower body divided at the neck) by using a regression analysis from a validation study in which BMC from a single scan of 20 subjects Ͻ183 cm in height was predicted from BMC based on the sum of two scans (y ϭ 1.003x Ϫ 46; r 2 ϭ 0.99; SE ϭ 30 g) (18). The regression equation was used because there was a small systematic difference (ϳ46 g) between BMC measured by using a single scan and that determined from two scans. ...
... A second possibility is that metabolic changes, such as alterations in enzyme content or activity, may have occurred, which render the muscle more efficient in its energy usage. It seems likely that the mechanism of T2 change is related to intracellular osmotic changes (27). Therefore, any training adaptation that results in a more efficient handling of osmotic loads, likely results in a lower T2 response. ...
... FIFA's Medical Assessment and Research Centre (FMARC) utilises both concentric and eccentric isokinetic knee testing during the preparticipation examination in an attempt to prevent injuries during the season (Brito et al., 2010). Muscular adaptations resulting from eccentric training include an increase in the crosssectional area of the muscle and specific neural adaptations, such as increased motor unit activation, a decreased activation of antagonistic muscles and a change in the angle of peak torque that may prevent hamstring strains (Higbie et al., 1996;Gabbe et al., 2006b;Brughelli & Cronin, 2007;Naclerio et al., 2013). In addition, eccentric exercise also relies on the involvement of the non-contractile components of the muscle, such as the connective tissue layers (epimysium, perimysium and endomysium). ...
... Compared with running at 1 % grade, maximal accumulated oxygen deficit increased by 37 % at 10.5 % grade and *80 % at 15 % grade, without any further increase at 20 % grade. Walker et al. [75] and Sloniger et al. [49] reported similar findings, with a 26 and 21 % increase in the maximal accumulated oxygen deficit as treadmill grade was increased from 0 to 10 %, respectively. Together, these findings may indicate that the maximal anaerobic energy production is greater during UR due to increased skeletal muscle mass activation in the lower limbs [49,62,75], even if differences in running efficiency as well as testing and calculations procedures (i.e. a linear relationship between work rate and energy demand) cannot be ruled out [76]. ...
... In a recent mfMRI study, acute low load BFR exercise induced accentuated R 2 decreases, increases in R 2 0 , reduced blood flow, and similar tissue fluid mobility (diffusion) compared to a heavier load in free-flow conditions (26). R 2 changes of muscle tissue during exercise, often referred to as a "T 2 shift" (T 2 = 1/R 2 ), correlates with acute muscle activity (27)(28)(29) and is metabolic in nature, as it is primarily driven by the changes in composition, pH, and volume of intracellular fluid following the accumulation of metabolites, such as lactate, after loading (30)(31)(32)(33)(34). R 2 data can also be used to estimate changes in the relative extra-/intracellular volume of muscle tissue. ...
... The principal physiological mechanisms of hydrotherapy in reducing pain, is that it increases in blood flow and metabolism, and increased elasticity of connective tissue [48] . Increasing tissue temperature stimulates vasodilation and increases tissue blood flow [49,50] , which is thought to promote healing by increasing the supply of nutrients and oxygen to the site of injury [48,51,52] . The rate of local tissue metabolism is also increased by warming, which may further promote healing. ...