Lateral Peak Research Articles

Isokinetic Peak Torque Ratios and Shoulder Injury History in Adolescent Female Volleyball Athletes

Few researchers have examined shoulder strength in adolescent volleyball athletes despite increasing levels of participation in this age group. To compare medial and lateral isokinetic peak torque of the rotator cuff among skill levels and between athletes with and without a history of shoulder injury. Cross-sectional design. The Human Performance Lab and Athletic Training Lab. Thirty-eight female adolescent club volleyball athletes from 10 to 15 years of age (mean = 13.02 +/- 1.60 years). We measured concentric and eccentric peak torque of the medial and lateral rotators of the shoulder and calculated resultant cocking and spiking ratios based on peak torque values. Athletes at higher skill levels had higher peak torque measurements in concentric and eccentric medial and lateral rotation compared with the athletes at lower skill levels. No differences in peak torque existed between participants with or without an injury history 6 months before the study. Strength ratios did not differ across skill levels, but previously injured participants produced lower eccentric medial rotation to concentric lateral rotation ratios compared with participants without a history of injury (P = .02). At the highest skill level, previously injured participants produced lower eccentric lateral rotation to concentric medial rotation ratios compared with participants without an injury history (P = .04). Differences in medial and lateral shoulder rotator strength ratios appear to be related more to injury prevalence than to absolute strength. Shoulder dysfunction related to strength ratio deficits also may exist in adolescent female volleyball athletes. Preventive shoulder strengthening programs focused on improving eccentric strength and correcting imbalances between medial and lateral rotators may be warranted for all female adolescent volleyball athletes.

The responsiveness of three-dimensional knee accelerations used as an estimation of knee instability and loading transmission during gait in osteoarthritis patient's follow-up

Knee instability and joint loading transmission are two important biomechanical factors in subjects with knee osteoarthritis (OA). However, the relationship between these factors in a rehabilitation treatment remains unclear. The purpose of this study is to determine the responsiveness of a new three-dimensional (3D) acceleration method used as an estimation of knee instability and joint loading transmission during gait in OA subjects after a rehabilitation treatment. Twenty-four subjects with medial knee OA were included in this study. They had clinical and gait evaluations before and after 12 weeks of treatment. 3D linear knee accelerations, quadriceps and hamstring isometric strength and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) pain were quantified, and compared between both evaluations. Nine asymptomatic subjects participated in this study for gait comparison. A significant reduction of the anterior posterior (AP) knee acceleration peak (P=0.02) had been detected after the treatment. No difference for both distal and lateral knee accelerations peak was found. A significant increase in quadriceps (P<0.001) and hamstring (P=0.006) strength was seen after treatment. The WOMAC of pain had shown significant reduction after the treatment (P<0.001). The present study demonstrates that the estimation of knee acceleration parameters is sensitive to changes in knee OA gait after a rehabilitation treatment. This study also indicates that a treatment of 3 months which combines therapeutic and exercises program could have benefits on knee OA by increasing AP knee stability and stabilize joint loading transmission during gait.

The Effect of Heart Rate on Tricuspid Annular Velocities in Cardiac Surgical Patients With Atrial Fibrillation

Tricuspid annular isovolumic acceleration is a load-independent measure of contractility, but its relationship to heart rate is unknown in humans. The authors investigated the effect of heart rate on measurements of isovolumic acceleration and systolic wave velocities in postoperative cardiac surgical patients with atrial fibrillation. This was a prospective observational study. Single-university hospital setting. Postoperative cardiac surgical patients with atrial fibrillation. None. Lateral tricuspid isovolumic acceleration and peak systolic wave velocity were measured using color-tissue Doppler. The corresponding heart rate was calculated from the preceding R-R interval. Regression analysis was used to assess the relationship between heart rate and tricuspid annular velocity. A heart rate threshold value was determined at which the tissue Doppler variables were significantly altered by heart rate. Seven hundred fifteen beats in 15 patients were analyzed. There was a positive linear correlation between isovolumic acceleration and heart rate and a negative polynomial correlation between the systolic wave and heart rate. A significant reduction in systolic wave velocity occurred at heart rates greater than 110 beats/min. In this patient population, isovolumic acceleration significantly increased with increasing heart rate. Tachycardia-induced preload alterations and impaired force-frequency responses may have been responsible for the decrease in systolic wave velocities.

Differences in Landing Forces in Individuals with and without Chronic Ankle Instability.

As individuals with chronic ankle instability (CAI) re-sprain their ankles multiple times, it is important to understand the medio-lateral ground reaction force (GRF) loading during common sideward sport movements. PURPOSE: To determine if individuals with CAI display lower GRF during medial and lateral single leg jump landings when compared to a control (CON) group. METHODS: Seventy volunteer recreational athletes, (CAI 15 males, 22 females; CON 16 males, 17 females). CAI participants reported a history of multiple inversion ankle sprains and ≥2 episodes of the ankle "giving way" in the last year. Controls reported none. Participants performed 10 medial and 10 lateral single leg jump landings onto the unstable ankle side (CAI) or the matched side (CON). Participants jumped a distance of 70 cm at 50% of their maximum vertical jump height and had to balance for 3s upon landing. GRFs were normalized to body weight (BW). Maximum magnitudes were identified in each GRF direction. Independent t-tests assessed group differences (α=0.05). RESULTS: For lateral jumps, the CAI group displayed smaller peak lateral GRF (0.59±0.10 BW) than the CON group (0.65±0.10 BW) (p=0.029). No differences were found for peak medial (CON 0.06±0.01 BW; CAI 0.08±0.11 BW, p=0.34) or vertical GRFs (CON 4.24±0.90 BW; CAI 4.03±0.70 BW, p=0.26). For medial jumps, no differences were observed for peak lateral (CON 0.05±0.02 BW; CAI 0.05±0.01 BW, p=0.67), medial (CON 0.84±0.21 BW; CAI 0.82±0.16 BW, p=0.66), or vertical GRFs (CON 4.02±0.75 BW; CAI 3.90±0.63 BW, p=0.48). CONCLUSION: The CAI group may have displayed lower lateral peak force during lateral jumps in order to decrease loading on lateral ankle ligaments. This provides further evidence of altered neuromuscular control patterns in CAI participants. Researchers may need participants to perform movements in multiple planes to identify GRF differences. These GRF differences may reveal movement pattern differences between CAI and CON groups. Supported by University of Georgia Research Foundation Grant.

The effect of diabetic neuropathy and previous foot ulceration in EMG and ground reaction forces during gait

Background We aimed at investigating the influence of diabetic neuropathy and previous history of plantar ulcers on electromyography (EMG) of the thigh and calf and on vertical ground reaction forces during gait. Methods This study involved 45 adults divided into three groups: a control group ( n = 16), diabetic neuropathic group ( n = 19) and diabetic neuropathic group with previous history of plantar ulceration ( n = 10). EMG of the right vastus lateralis, lateral gastrocnemius and tibialis anterior were studied during the stance phase. The peaks and time of peak occurrence were determined and a co-activation index between tibialis anterior and lateral gastrocnemius. In order to represent the effect of the changes in EMG, the first and second peaks and the minimum value of the vertical ground reaction force were also determined. Inter-group comparisons of the electromyographical and ground reaction forces variables were made using three MANCOVA (peaks and times of EMG and peaks of force) and one ANCOVA (co-activation index). Findings The ulcerated group presented a delayed in the time of the lateral gastrocnemius and vastus lateralis peak occurrence in comparison to control’s. The lateral gastrocnemius delay may be related to the lower second vertical peak in diabetic subjects. However, the delay of the vastus lateralis did not cause any significant change on the first vertical peak. Interpretations The vastus lateralis and lateral gastrocnemius delay demonstrate that ulcerated diabetic neuropathic patients have a motor deficit that could compromise their ability to walk, which was partially confirmed by changes on ground reaction forces during the push-off phase.

Left atrial myocardial function in either physiological or pathological left ventricular hypertrophy: a two-dimensional speckle strain study

Background:Atrial function is an integral part of cardiac function that is often neglected. The presence of left ventricule hypertrophy (LVH) due to arterial hypertension may impair atrial function. However, it...

EFFECTS OF DIFFERING RESPONSE‐FORCE REQUIREMENTS ON FOOD‐MAINTAINED RESPONDING IN CD‐1 MICE

The effect of force requirements on response effort was examined using outbred (CD-1) mice trained to press a disk with their snout. Lateral peak forces greater than 2 g were defined as threshold responses (i.e., all measured responses). Different force requirements were used to define criterion responses (a subclass of threshold responses) that exceeded the requirement. The reinforcer was sweetened, condensed milk, and it was delivered upon response termination. All mice were exposed to two ascending series of criterion force requirements (2, 4, 8, 16, and 32 g). Increasing the force requirement decreased criterion response rates, but increased threshold response rates. The time-integral of force (area under the force-time curve for individual responses, which is proportional to energy expenditure for each response) increased with the increase in the force requirement. These results conflict with the hypothesis that higher force requirements have aversive qualities and suggest that increased force requirements are more analogous to intermittent schedules of reinforcement. These data suggest that estimations of effort or energy expenditure should be measured independently of the force requirement. Individual differences in responding were found for the CD-1 outbred stock.

Subregions of the ventral striatum show preferential coding of reward magnitude and probability

As shown in non-human primate and human fMRI studies the probability and magnitude of anticipated rewards modulate activity in the mesolimbic dopaminergic system. Importantly, non-human primate data have revealed that single dopaminergic neurons code for both probability and magnitude of expected reward, suggesting an identical system. Using a guessing task that allowed the independent assessment of the factors probability and magnitude we were able to assess the impact of reward probability and magnitude in ventral striatal subregions in a large sample (n=98). We observed more anterior and lateral peak activation foci in the ventral striatum for reward probability and a more posterior and medial activation peak for reward magnitude, suggesting a functional segregation at the mesoscopic level. Importantly, this functional bias observed for the group average was also tested in each individual subject, allowing for proper random effects inference for the spatial dissociation. Taken together, our data point toward a functional dissociation of neuronal assemblies suggesting that certain populations of neurons are more sensitive to expected reward probability and other populations are more sensitive to reward magnitude.

Effect of Obesity on Left Ventricular Structure and Myocardial Systolic Function: Assesment by Tissue Doppler Imaging and Strain/Strain Rate Imaging

Obesity is associated with heart failure, cardiovascular morbidity, and mortality. A direct effect of weight on left ventricle (LV) structure and myocardial function is not well-established. The aim of our study is to determine the effect of obesity on LV morphology and systolic function by using LV standard Doppler echocardiographic indices, myocardial Doppler imaging and strain/strain rate imaging indices. We studied 33 obese and 34 age, sex-adjusted control subjects who had no other pathological conditions. Standard transthoracic Doppler echocardiographical measurements, reconstructed spectral pulsed wave tissue Doppler velocities, strain and strain rate imaging of six different myocardial regions were obtained. Peak systolic velocity (SR), peak systolic strain (I), peak systolic strain rate (SR) for each region and as a global systolic longitidunal LV function mean of peak systolic strain of six myocardial regions (glsca) were compared. Age, body surface area, blood pressure, and heart rate were comparable between the two groups. Obese subjects had significantly increased LV end-diastolic volume, septal wall thickness, left atrial diameter, and decreased transmitral early to late diastolic velocity ratio. In obese subjects, reconstructed spectral pulsed-wave tissue Doppler analysis showed significantly decreased basal lateral peak systolic (Sm) velocity (6.68 +/- 1.89 vs. 8.08 +/- 2.50, P < 0.05), mid lateral Sm (5.01 +/- 2.17 vs. 6.78 +/- 3.22, P < 0.05). Differences in regional strain rate (mid septal SR, 1.45 +/- 0.23 vs. 1.63 +/- 0.18, P < 0.05), regional strain (basal septum I, 19.13 +/- 3.83 vs. 22.09 +/- 4.60, P < 0.05; mid-septum I, 18.03 +/- 2.91 vs. 20.25 +/- 4.77, P < 0.05; radial I, 27.50 +/- 7.32 vs. 35.53 +/- 9.48, P < 0.05), and global strain (glsca, 19.38 +/- 1.34 vs. 21.24 +/- 2.82, P < 0.05) were identified between obese and the referent subjects. Obesity is associated with morphologic alterations in left ventricle and left atrium and subclinical changes in left ventricle systolic function which can be detected by strain and strain rate imaging even without overt heart disease.

Left ventricular function in professional football players evaluated by tissue Doppler imaging and strain imaging

Long-term regular exercise is associated with physiologic and morphologic cardiac alterations. Tissue Doppler Imaging(TDI) and Strain Myocardial Imaging(SI) are new tools in the evaluation systolic and diastolic myocardial function. We sought to compare TDI and SI findings in professional football players and age adjusted sedentary controls to assess the effect of regular athletic training on myocardial function. Transthoracic echocardiography, M-mode, 2-D measurements, Doppler derived mitral-tricuspid annular velocities, reconstructed spectral pulsed wave tissue Doppler velocities, strain and strain rate imaging of seven different myocardial regions were obtained from 24 professional football players and age, sex and weight adjusted 20 controls. Age, body surface area, blood pressure and heart rate were comparable between 2 groups. Football players had significantly increased LV mass, mass index (due to both higher wall thickness and end-diastolic diameter), end-systolic and end-diastolic volume, left atrial diameter and decreased transmitral diastolic late velocity. In athletes TDI analysis showed significantly increased mitral annulus septal TDI peak early diastolic(e) velocity(0.22 +/- 0.04 vs. 0.19 +/- 0.04 m/s, P < 0.05), lateral TDI peak e velocity (0.19 +/- 0.03 vs. 0.16 +/- 0.02 m/s, P < 0.05) and lateral TDI e/a ratio (1.96 +/- 0.41 and 1.66 +/- 0.23, P < 0.05). In SI analysis mid septal walls (1.71 +/- 0.23 in athletes and 1.49 +/- 0.25 in controls, P < 0.05) and mid lateral walls (1.55 +/- 0.28 and 1.34 +/- 0.25 respectively, P < 0.05) peak systolic strain rate values differences were found to be increased in athletes. Professional football playing is associated with morphologic alteration in left ventricle and left atrium and improvement in left ventricle diastolic function which can be detected by TDI. Strain rate imaging may be a new tool to define subtle change in systolic left ventricular function in "athletes heart" which cannot be determined in standard echocardiographic parameters.

Effect of Obstruction on Longitudinal Left Ventricular Shortening in Hypertrophic Cardiomyopathy

We investigated the cause of the midsystolic drop (MSD) in left ventricular (LV) ejection velocities that are observed with hypertrophic cardiomyopathy (HCM) and severe obstruction. Dynamic obstruction is an important determinant of symptoms and adverse outcome. The MSD in velocity and flow occurs in patients with gradients >60 mm Hg. The nadir velocity in the LV occurs simultaneously with peak gradient. We studied 36 patients with obstructive HCM and an MSD and compared them with 15 patients with HCM and no obstruction and with 25 age-matched normal control subjects. We measured LV ejection velocity proximal and distal to LV obstruction as well as tissue Doppler velocities and time intervals. The duration of contraction of both the septum and lateral wall is shorter in obstructed patients with the MSD than in nonobstructed HCM patients: septal contraction 203 +/- 68 ms vs. 271 +/- 41 ms (p < 0.001). Parallel reduction in the length of shortening was noted: 1.2 +/- 0.6 cm vs. 1.9 +/- 0.4 cm (p < 0.001). The ejection velocity nadir follows the septal and lateral peak velocities by 100 ms and 60 ms, respectively. The velocity nadir occurs as both walls rapidly decelerate to their premature termination: septal deceleration 79 +/- 35 cm/s2 vs. 48 +/- 21 cm/s2 (p < 0.001). With medical abolition of obstruction the MSD disappears and the duration and length of contraction normalizes. These data indicate that the MSD is caused by premature termination of LV segmental shortening and is a manifestation of systolic dysfunction.

Cardiac resynchronization therapy for an unusual cause of cardiomyopathy

A 66 year old woman with symptomatic cardiac failure, despite treatment with diuretics, a β-blocker and an ACE inhibitor was referred for consideration of cardiac resynchronization therapy (CRT). Co-morbidity included chronic renal impairment and type II diabetes mellitus. An electrocardiogram demonstrated sinus rhythm, first degree block and left bundle branch block of 160 ms duration. Coronary angiography was normal and transthoracic 2D echocardiography showed severe left ventricular systolic dysfunction with extensive and abnormal trabeculation of the left ventricular lateral, anterior and apical segments. Significant interventricular dys-synchrony (63 ms delay in left vs. right ventricular ejection on Doppler) and intra-ventricular dyssynchrony of the left ventricle were also found (208 ms delay in posteroseptal vs. anteroseptal peak wall thickening on M-mode and with tissue Doppler a 220 ms delay of the basal lateral vs. basal septal segment peak systolic velocity). Moreover, the appearances were highly suggestive of isolated

Alterations in Left Ventricular Structure and Diastolic Function in Professional Football Players: Assessment by Tissue Doppler Imaging and Left Ventricular Flow Propagation Velocity

Long-term regular exercise is associated with physiologic and morphologic cardiac alterations. Tissue Doppler imaging (TDI) and ventricular early flow propagation velocity (Vp) are new tolls in the evaluation of myocardial function. We sought to compare TDI and Vp findings in professional football players and age-adjusted sedentary controls to assess the effect of regular athletic training on myocardial function. Twenty-four professional football players and age-, sex-, and weight-adjusted 20 control subjects underwent standard Doppler echocardiography pulsed TDI, performed parasternal four-chamber views by placing sample volume septal and lateral side of mitral annulus and lateral tricuspid annulus. Vp values were obtained by measuring the slope delineated by first aliasing velocity from the mitral tips toward the apex by using apical four-chamber color M-mode Doppler images. Age, body surface area, blood pressure, and heart rate were comparable between two groups. Football players had significantly increased LV mass, mass index (due to both higher wall thickness and end-diastolic diameter), end-systolic and end-diastolic volume, left atrial diameter, and decreased transmitral diastolic late velocity. In athletes TDI analysis showed significantly increased mitral annulus septal DTI peak early diastolic (e) velocity (0.22 +/- 0.04 vs 0.19 +/- 0.04, P < 0.05), lateral DTI peak e velocity (0.19 +/- 0.03 vs 0.16 +/- 0.02, P < 0.05) and lateral DTI e/a peak velocity ratio (1.96 +/- 0.41 and 1.66 +/- 0.23, P < 0.05). The ratio of transmitral peak early diastolic velocity (E) to e in both lateral (4.72 +/- 1.20 vs 5.95 +/- 1.38, P = 0.007) and septal (3.90 +/- 0.80 vs 5.25 +/- 1.50, P = 0.002) side of mitral annulus were significantly lower in athletes. In Vp evaluation, we found higher Vp values (60.52 +/- 6.95 in athletes and 56.56 +/- 4.24 in controls, P = 0.03) in football players. Professional football playing is associated with morphologic alteration in left ventricle and left atrium and improvement in left ventricle diastolic function that can be detected by TDI and Vp. These techniques may be new tools to define and quantitate the degree of LV diastolic adaptations to endurance exercise.

Evaluation of echocardiography indices of systolic function: a comparative study using pressure‐volume loops in patients undergoing coronary artery bypass surgery*

Transoesophageal echocardiography measures of systolic left ventricular function obtained during coronary artery bypass surgery are heavily influenced by alterations in loading conditions. No validation of these measurements against load independent indices obtained by pressure-volume loop analysis has been undertaken in humans. Ten patients undergoing coronary artery bypass surgery underwent simultaneous transoesophageal echocardiography and pressure-volume loop analysis of cardiac function at different loading conditions (reduced preload, increased afterload and atrial pacing). Fractional area change, afterload corrected fractional area change, and lateral basal wall peak systolic myocardial velocity, along with dP/dt, were compared to the preload recruitable stroke work relationship. There were no significant differences between the echocardiography measures when compared to the preload recruitable stroke work relationship; however, dP/dt varied significantly across loading conditions (p<0.001). Transoesophageal echocardiography adequately assesses systolic function across loading conditions commonly seen during coronary artery bypass surgery.

Biofeedback supplementation to physiotherapy exercise programme for rehabilitation of patellofemoral pain syndrome: a randomized controlled pilot study

Objectives: To examine the efficacy of electromyographic (EMG) biofeedback supplementation to exercise rehabilitation for people with patellofemoral pain syndrome. Design: Double-blinded randomized clinical controlled pilot trial. Setting: Clinical setting with home programme. Participants: Twenty-six subjects diagnosed with patellofemoral pain. Intervention: Subjects were randomly assigned into EMG biofeedback+exercise group or exercise-only group. All subjects participated in an eight-week home exercise programme, while the biofeedback group also received EMG visual feedback of their quadriceps muscle activities during the exercises. Main outcome measures: Isokinetic knee extension strength, patellar alignments and perceived pain severity were assessed in weeks 0, 4 and 8 for all subjects. The data within and between groups were compared by repeated measures ANOVA with aα=0.05. Results: Both groups improved in isokinetic peak torque (P=0.005), work output (P=0.037) and patellar alignments (P=0.001-0.014). Besides, there was a trend of decrease in pain (P=0.088). The biofeedback group improved faster than the exercise group in lateral patellar rotation and peak torque per body weight, although no statistically significant difference was shown. Conclusion: Biofeedback supplement to the exercise programme might hasten the improvement for subjects with patellofemoral pain in the first few weeks of a physiotherapy exercise programme, but this needs further study before being used.

Timescales and significance of high-pressure, high-temperature metamorphism and mafic dike anatexis, Snowbird tectonic zone, Canada

New geochronological, isotopic and geochemical data for a spectacular swarm of deep crustal migmatitic mafic dikes offer important insight into processes operative during 1.9 Ga high pressure, high temperature metamorphism along the Snowbird tectonic zone in northern Saskatchewan. High-precision U–Pb zircon dates reveal anatexis of Chipman mafic dikes at 1,896.2 ± 0.3 Ma during syntectonic and synmetamorphic intrusion at conditions of 1.0–1.2 GPa, >750°C. U–Pb zircon dates of 1,894–1,891 Ma for cross-cutting pegmatites place a lower bound on major metamorphism and deformation at the currently exposed crustal levels. The persistence of elevated temperatures for ~14 m.y. following peak conditions is implied by younger U–Pb titanite dates, and by Sm–Nd whole rock isotopic data that suggest the derivation of the pegmatites by melting of a mafic source. Limited melting of the host felsic gneiss at 1.9 Ga despite high temperature is consistent with evidence for their previous dehydration by granulite facies metamorphism in the Archean. Spatial heterogeneity in patterns of mafic dike and tonalitic gneiss anatexis can be attributed to lateral peak temperature and compositional variability. We correlate 1,896 Ma Chipman mafic dike emplacement and metamorphism with substantial 1.9 Ga mafic magmatism over a minimum along-strike extent of 1,200 km of the Snowbird tectonic zone. This suggests a significant, continent-wide period of asthenospheric upwelling that induced incipient continental rifting. Extension was subsequently terminated by hinterland contraction associated with Trans-Hudson accretion and orogenesis. Little activity in the lower crust for ca. 650 m.y. prior to Proterozoic metamorphism and mafic magmatism implies an extended interval of cratonic stability that was disrupted at 1.9 Ga. This episode of destabilization contrasts with the record of long-term stability in most preserved cratons, and is important for understanding the lithospheric characteristics and tectonic circumstances that control the destruction or survival of continents.

Reverse Remodeling of the Left Cardiac Chambers After Catheter Ablation After 1 Year in a Series of Patients With Isolated Atrial Fibrillation

Isolated atrial fibrillation (AF) is associated with mild enlargement of the left atrium (LA) and left ventricular (LV) diastolic dysfunction. The impact of ablation of isolated AF on left chamber size and function is unclear, and whether diastolic dysfunction is the cause or the consequence of AF remains unknown. The objective of this prospective study was to evaluate the impact of sinus rhythm restoration by catheter ablation on LV diastolic dysfunction, LA morphology, and mechanical function. Forty-eight patients with isolated AF were studied by serial echocardiographic studies at baseline and at 1-, 3-, 6-, 9-, and 12-month intervals after radiofrequency ablation. LA dimensions and mechanical function and LV systolic and diastolic functions were evaluated at each time interval. Diastolic function was assessed with conventional Doppler parameters and new indexes such as tissue Doppler imaging, mitral flow propagation velocity, and combined criteria. LV diastolic dysfunction was present in paroxysmal and chronic AF patients with a reduction of tissue Doppler imaging lateral early diastolic peak velocity in 37% (P<0.001) and 48% (P<0.01), respectively, compared with healthy control subjects. At the end of the follow-up, LA area decreased significantly by 18% (P<0.001) in paroxysmal and 23% (P<0.05) in chronic AF patients. Diastolic function improved significantly with an increase in lateral early diastolic peak velocity of 29% (P<0.001) in paroxysmal AF and 46% (P<0.05) in chronic AF patients. A significant increase in LV ejection fraction was also noted for both groups: 7.7% and 18.8%, respectively. This study demonstrates reverse morphological remodeling of the LA and improvement of LV diastolic and systolic functions after restoration of sinus rhythm by ablation for isolated AF. Because patients with isolated AF have none of the traditional causes of LV diastolic dysfunction, our findings suggest that AF may be partly the cause rather than the consequence of diastolic dysfunction.

Assessment of left ventricular diastolic function by early diastolic mitral annulus peak acceleration rate: experimental studies and clinical application

We sought to examine the hemodynamic determinants and clinical application of the peak acceleration rate of early (Ea) diastolic velocity of the mitral annulus by tissue Doppler. Simultaneous left atrial and left ventricular (LV) catheterization and Doppler echocardiography were performed in 10 dogs. Preload was altered using volume infusion and caval occlusion, whereas myocardial lusitropic state was altered with dobutamine and esmolol. The clinical application was examined in 190 consecutive patients (55 control, 41 impaired relaxation, 46 pseudonormal, and 48 restrictive LV filling). In addition, in 60 consecutive patients, we examined the relation between it and mean wedge pressure with simultaneous Doppler echocardiography and right heart catheterization. In canine studies, a significant positive relation was present between peak acceleration rate of Ea and transmitral pressure gradient only in the stages with normal or enhanced LV relaxation, but with no relation in the stages where the time constant of LV relaxation (tau) was > or =50 ms. Its hemodynamic determinants were tau, LV minimal pressure, and transmitral pressure gradient. In clinical studies, peak acceleration rate of Ea was significantly lower in patients with impaired LV relaxation irrespective of filling pressures (P < 0.001) and with similar accuracy to peak Ea velocity (area under the curve for septal and lateral peak acceleration rates: both 0.78) in identifying these patients. No significant relation was observed between peak acceleration rate and mean wedge pressure. Peak acceleration rate of Ea appears to be a useful index of LV relaxation but not of filling pressures and can be applied to identify patients with impaired LV relaxation irrespective of their filling pressures.

Footprint peak time and functional ambulation profile reflect the potential for hemiparetic gait recovery

Objective: Gait disturbances were monitored in patients with chronic stroke with a walkway built with pressure sensors in order to assess whether detailed gait and footprint information could provide verification for the potential for gait recovery.Methods: Gait variables (footprint peak times, temporal and spatial parameters and Functional Ambulation Profile, FAP, scores), were first recorded in 25 patients with chronic stroke at their preferred speed and 10 healthy volunteers walking from very slow to very fast. Patients and controls were divided into four groups based on the velocity performance. Secondly, the effect of rehabilitation on the footprint peak times was evaluated in another group of 20 chronic stroke patients.Results and conclusions: The footprint peak time behaviour of different patients with chronic stroke reflected their hemiparetic gait pattern. The slower patients had prolonged footprint peak times on the non-affected side (NS) and shorter values on the lateral footprint on the affected side (AS). The increased gait velocity and the FAP scores decreased the footprint peak times on both sides, especially on the NS. The rehabilitation increased the gait velocity with 18.2%, decreased the duration of the mid-foot and forefoot peak times on the NS and the lateral mid-foot peak times on the AS. A detailed analysis of the individual gait performance allows more accurate assessment of the potential for gait recovery.

Isokinetic neck strength norms for schoolboy rugby forwards

Objective. To generate isokinetic neck strength norms for schoolboy rugby forwards. Design. Two hundred and eight schoolboys (17.21 – 1.03 years, mean – standard error of the mean (SEM), chosen from a population of under-19 first and second XV rugby players, participated in this study. The subjects were assessed anthropometrically and isokinetically according to a set protocol. The isokinetic assessment of neck strength was performed with the use of a specially designed stabilising chair and halo. The subjects performed a single maximal exertion set, consisting of 3 repetitions, through each of the cervical spinal movements in the sagittal and frontal planes. The data were analysed statistically according to positional categories (front-, second-, and back-row forwards), and were used to generate Stanine tables of normative data concerning the force characteristics of the cervical spine. Results. The front-row forwards produced the largest amounts of force during the measurement of peak torque flexion (PTF = 30.00 – 1.39 Nm) and peak torque extension (PTE = 55.26 – 1.42 Nm). Conversely, the second-row forwards performed the best during the measurement of lateral flexion peak torque to the right (PTR = 53.71 – 1.51 Nm) and lateral flexion peak torque to the left (PTL = 52.92 – 1.63 Nm) in the frontal plane. The front-row forwards were the most powerful in all the neck movements measured (power generated at 0.2 seconds during flexion (PowF) = 101.54 – 6.43 W, power generated at 0.2 s during extension (PowE) = 167.31 – 8.03 W, power generated at 0.2 s during lateral flexion to the right (PowR) = 211.92 – 7.44 W, and power generated at 0.2 s during lateral flexion to the left (PowL) = 194.81 – 7.73 W). However, further analysis of the data revealed that few statistically significant differences (p &lt; 0.01 and p &lt; 0.05) existed between the positional categories for the measured variables of peak torque, power generated at 0.2 of a second, peak torque to body mass ratio and cervical range of motion. Conclusion. It appears that the various positional categories have not undergone the expected neck strength adaptations to meet the unique requirements of each position. The generation of neck strength normative data allows for the effective and quantified comparison of neck strength variables, enabling more effective injury prevention and rehabilitation. South African Sports Medicine Vol.17(1) 2005: 19-26