ABSTRACT
The purpose of this study was to examine the effectiveness of weight-belts during multiple repetitions of the parallel back squat exercise. Five subjects were filmed (50 fps) as they performed eight consecutive trials at each of two weight-belt conditions [with belt = WB, without belt = WOB] in random order at their eight-repetition maximum effort. Other parameters examined were ground reaction forces, intra-abdominal pressure (IAP), and mean electromyography (mEMG) for the external oblique (EO), erector spinae (ES), vastus lateralis (VL), and bicep femoris (BF) muscles. All parameters were collected and interfaced to a computer via an A/D converter. WB repetitions were generally performed faster than WOB repetitions, especially by the later repetitions (3.34 vs 3.56 s). WB IAP values were consistently greater (P less than 0.05) than WOB values by 25-40%. IAP increased by approximately 11.5% from the first to the last repetitions. No differences were observed for ES and EO mEMG for belt usage, but values increased by up to 20% across repetitions. Several differences were observed between WB and WOB for the VL and BF mEMG, with WB values being significantly greater. These data suggest that a weight-belt aids in supporting the trunk by increasing IAP, and that any differential effect due to wearing a weight-belt did not occur over eight repetitions.
Subject(s)
Physical Education and Training , Protective Devices , Weight Lifting , Abdominal Muscles/physiology , Adult , Electromyography , Humans , Male , Pressure , Spine/physiologyABSTRACT
The purpose of this study was to examine the effectiveness of weight-belts during the performance of the parallel squat exercise. Six subjects were filmed (40 fps) as they performed three trials at each of three belt conditions (NB, none; LB, light; HB, heavy) in random order and three load conditions (70, 80, 90% 1RM (one repetition maximum] in increasing order. The parameters examined were collected and interfaced to a computer via an analog-to-digital (A/D) converter: ground reaction forces, intra-abdominal pressure (IAP), and EMG for the rectus abdominus (RA), external oblique (EO), and erector spinae (ES) muscles. Most differences were observed during the 90% 1RM condition, and only they are presented in this paper. Maximum IAP values were always greater (P less than 0.05) for the weight-belt conditions (LB, 29.2; HB, 29.1 greater th an NB, 26,8 kPa). Similar results were observed for the mean IAP. The integrated EMG (iEMG) activity of the muscles and adjusted mean values for back compressive force and back muscle force followed a similar but opposite pattern, with NB being the greatest. ES mEMG/(L5/S1) values for HB (18.1%) were the least, followed by LB (20.01%) and NB (22.3%). Few differences were observed between belt types. These data suggest that a weight-belt can aid in supporting the trunk by increasing IAP.
Subject(s)
Protective Devices , Weight Lifting , Abdomen/physiology , Adult , Biomechanical Phenomena , Electromyography , Equipment Design , Evaluation Studies as Topic , Humans , Joints/physiology , Male , Pressure , Spine/physiology , Weight Lifting/injuriesABSTRACT
An analysis of pharmacokinetic parameters of digoxin was carried out in six premature infants after the administration of a single total digitalizing dose of 20 microgram/kg. The data was analyzed using both a 2 and 3 exponential model. In the premature infant, the plasma half-life of digoxin is prolonged, while the volume of the central compartment, total body clearance, volume of distribution and volume of distribution at steady state are reduced compared to other aged patients.
Subject(s)
Digoxin/metabolism , Infant, Premature , Digoxin/blood , Half-Life , Heart Failure/congenital , Heart Failure/drug therapy , Humans , Infant, Newborn , Injections, Intravenous , KineticsABSTRACT
A bilaterally induced mechanical lesion of the midbrain was highly effective in abolishing the hindlimb extensor (HLE) component of the maximal electroshock seizures (MES) in rats. Although these lesions produced damage to a variety of midbrain structures, correlations between different lesion placements and effects in the MES test provided evidence that damage to superior cerebellar peduncle (PCS) and/or reticular formation (RF) was responsible for inhibition of hindlimb extension. Moreover, discretely placed electrolytic lesions disrupting either the PCS or the RF were found to abolish the hindlimb extensor component of the MES test. These findings are consistent with the work of other investigators showing that total cerebellectomy abolishes the HLE component of MES and suggest that activity in the cerebellum and the midbrain reticular formation plays a major role in regulating the tonic phase of electroshock induced seizures.
Subject(s)
Electroshock , Pons/physiology , Seizures/physiopathology , Tegmentum Mesencephali/physiology , Animals , Cerebellum/physiopathology , Disease Models, Animal , Hindlimb , Male , Muscles/physiopathology , Rats , Reticular Formation/physiopathology , Seizures/etiologyABSTRACT
Midbrain tegmental lesions, which prevent the hindlimb extensor (HLE) component of maximal electroshock seizures (MES), were found to have no effect on the electroshock, flurothyl, or pentylenetetrazol (PTZ) seizures thresholds. However, these lesions were found to antagonize the HLE component of the maximal PTZ seizure, and to elevate the threshold for electroshock induced tonic flexion. These findings suggest that lesion of the midbrain tegmentum involving the superior cerebellar peduncle and/or the midbrain reticular formation antagonize the tonic component of generalized seizures, but have little or no effect on the clonic component.
