Physiological, perceptual, and biomechanical differences between treadmill and overground walking in healthy adults: A systematic review and meta-analysis

This systematic review and meta-analysis aims to compare physiological, perceptual and biomechanical outcomes between walking on a treadmill and overground surfaces. Five databases (CINAHL, EMBASE, MEDLINE, SPORTDiscus, Web of Science) were searched until September 2022. Included studies needed to be a crossover design comparing biomechanical, physiological, or perceptual measures between motorised-treadmill and overground walking in healthy adults (18-65 years) walking at the same speed (<5% difference). The quality of studies were assessed using a modified Downs and Black Quality Index. Meta-analyses were performed to determine standardised mean difference ± 95% confidence intervals for all main outcome measures. Fifty-five studies were included with 1,005 participants. Relative oxygen consumption (standardised mean difference [95% confidence interval] 0.38 [0.14,0.63]) and cadence (0.22 [0.06,0.38]) are higher during treadmill walking. Whereas stride length (-0.36 [-0.62,-0.11]) and step length (-0.52 [-0.98,-0.06]) are lower during treadmill walking. Most kinetic variables are different between surfaces. The oxygen consumption, spatiotemporal and kinetic differences on the treadmill may be an attempt to increase stability due to the lack of control, discomfort and familiarity on the treadmill. Treadmill construction including surface stiffness and motor power are likely additional constraints that need to be considered and require investigation. This research was supported by an Australian Government Research Training Program (RTP) scholarship. Protocol registration is CRD42020208002 (PROSPERO International Prospective Register of Systematic Reviews) in October 2020.

Not as simple as it seems: Front foot contact kinetics, muscle function and ball release speed in cricket pace bowlers

This study investigated the relationship between front foot contact (FFC) ground reaction forces (GRF) during the delivery stride, lower-limb strength, eccentric dexterity and power, and ball release speed (BRS) among pace bowlers. Thirteen high-level male pace bowlers performed double and single leg drop landings; isometric mid-thigh pull; countermovement jump; and pace bowling (two-over bowling spell measuring BRS and FFC GRF). The relationship between assessed variables and BRS was determined via frequentist and Bayesian multiple linear regression. The model including peak braking force was the most probable given the data (Bayes Factor=1.713) but provided only weak evidence in comparison to the null model. The results of frequentist and Bayesian modelling were comparable with peak braking force explaining 23.3% of the variance in BRS (F_{(1, 11)}=4.64, P=0.054). Results indicate pace bowlers with greater peak braking GRF during FFC generally elicit higher BRS. However, the weak relationship between peak braking force and BRS, and the lack of a linear relationship between BRS and other variables, highlights the complexities and inter-individual variability inherent to pace bowling at a high-level. A more individual-focused analysis revealed varied strategies within pace bowlers to deliver the outcome (e.g., BRS) and should be considered in future study designs.

The influence of elbow joint kinematics on wrist speed in cricket fast bowling

This modelling study sought to describe the relationships between elbow joint kinematics and wrist joint linear velocity in cricket fast bowlers, and to assess the sensitivity of wrist velocity to systematic manipulations of empirical joint kinematic profiles. A 12-camera Vicon motion analysis system operating at 250 Hz recorded the bowling actions of 12 high performance fast bowlers. Empirical elbow joint kinematic data were entered into a cricket bowling specific "Forward Kinematic Model" and then subsequently underwent fixed angle, angular offset and angle amplification manipulations. A combination of 20° flexion and 20° abduction at the elbow was shown to maximise wrist velocity within the experimental limits. An increased elbow flexion offset manipulation elicited an increase in wrist velocity. Amplification of elbow joint flexion-extension angular displacement indicated that, contrary to previous research, elbow extension range of motion and angular velocity at the time of ball release were negatively related to wrist velocity. Some relationships between manipulated joint angular waveforms and wrist velocity were non-linear, supporting the use of a model that accounts for the non-linear relationships between execution and outcome variables in assessing the relationships between elbow joint kinematics and wrist joint velocity in cricket fast bowlers.

Regression of left ventricular hypertrophy after nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy

BACKGROUND

Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by left ventricular hypertrophy (LVH) in the absence of increased external load. Recently, nonsurgical septal reduction therapy (NSRT) with intracoronary ethanol has been introduced to treat severely symptomatic patients with outflow tract obstruction. Its long-term effects on LV mass, however, are unknown.

METHODS AND RESULTS

The LV size, function, and outflow tract gradient of 26 HOCM patients (53+/-15 years old) who underwent NSRT were assessed by echocardiography at baseline and 1 and 2 years after the procedure. LVH was evaluated by wall thickness of individual myocardial segments, planimetered myocardial area, and mass. The outflow gradient decreased from 36+/-6 mm Hg before NSRT to 0+/-3 mm Hg at 2 years (P<0.001), with patients experiencing symptomatic improvement (P<0.05). LV end-diastolic and end-systolic dimensions increased significantly at both 1 and 2 years (P<0.001). All parameters of LVH showed evidence of regression. LV mass decreased (301+/-78 g at baseline, 223+/-5 g at 1 year, and 190+/-58 g at 2 years; P<0.01), with the 2-year reduction in mass related to infarct size and the acute reduction in outflow tract gradient (r=0.48, P<0.05 and r=0.63, P<0.01, respectively).

CONCLUSIONS

NSRT results in LV remodeling that is characterized by an increase in LV size and a decrease in the extent of LVH.

Echocardiographic insights into the mechanisms of relief of left ventricular outflow tract obstruction after nonsurgical septal reduction therapy in patients with hypertrophic obstructive cardiomyopathy

OBJECTIVES

We sought to evaluate the mechanisms by which nonsurgical septal reduction therapy (NSRT) reduces left ventricular outflow tract (LVOT) obstruction in patients with hypertrophic obstructive cardiomyopathy (HOCM) both acutely and on a long-term basis.

BACKGROUND

NSRT reduces LVOT obstruction in patients with HOCM and leads to symptomatic improvement. The mechanisms involved, however, are not well studied.

METHODS

An initial group of 30 HOCM patients (age 46 +/- 17, 16 women) who underwent NSRT had echocardiographic studies performed at baseline and six months after the procedure. Measurements included LVOT diameter, end-diastolic distance between the anterior mitral leaflet and interventricular septum, septal base function and the angle between LV systolic flow and the protruding mitral leaflets. In addition, pulse Doppler recordings at a point 2.5 cm apical to the mitral valve were acquired and analyzed for peak and mean ejection velocity, peak acceleration rate and the ratio of acceleration time to ejection time (AT/ET).

RESULTS

Significant changes were observed after the procedure, with widening in the LVOT, thinning and akinesis of the septal base, decrease in the angle between LV systolic flow and the protruding mitral leaflets, a decrease in peak acceleration rate and an increase in AT/ET. All of these variables had significant relations with the decrease in LVOT obstruction (r = 0.5 to 0.79, p < 0.01). These correlations were then evaluated in a test group of 15 patients who underwent echocardiographic examinations at baseline, acutely in the catheterization laboratory with ethanol injection and at six weeks post NSRT. Acute changes in peak acceleration rate (r = 0.65) and AT/ET (r = 0.73) related significantly (p < 0.01) to the decrease in LVOT obstruction with ethanol. At six weeks, changes similar to those noted in the initial group were observed in LVOT geometry, the angle between LV systolic flow and the protruding mitral leaflets, peak acceleration rate and AT/ET. In both populations combined, these parameters accounted for 72% to 77% of the variance in gradient reduction.

CONCLUSIONS

Changes in LV ejection dynamics and septal base function account in part for the acute relief of LVOT gradient after NSRT. The long-term relief of obstruction is dependent on remodeling of LVOT as well as the changes in LV ejection.

Hemodynamic determinants of the mitral annulus diastolic velocities by tissue Doppler

OBJECTIVES

Our goal was to identify the hemodynamic determinants of the mitral annulus (MA) diastolic velocities by tissue Doppler.

BACKGROUND

The MA diastolic velocities are promising indexes of left ventricular (LV) diastolic function. However, their hemodynamic determinants have not yet been evaluated.

METHODS

Ten adult mongrel dogs underwent left atrial (LA) and LV pressure measurements by Millar catheters while tissue Doppler was applied to record the MA diastolic velocities at the septal and lateral comers. Conventional transmitral flow was also obtained. Left atrial and LV pressures were modified utilizing fluid administration and caval occlusion, whereas dobutamine and esmolol were used to change LV and LA relaxation. Left ventricular filling pressures were altered during different lusitropic states to evaluate for the possible interaction of preload and LV relaxation on the early diastolic velocity (Ea).

RESULTS

In the majority of dogs, a positive significant relation was observed between Ea and the transmitral pressure gradient (r = 0.57, p = 0.04). The Ea had strong correlations with tau (r = -0.83, p < 0.001), LV -dP/dt (r = 0.8, p < 0.001) and minimal LV pressure (r = -0.76, p < 0.01). However, there was no relation between Ea and the transmitral pressure gradient in experimental stages where tau >50 ms. Furthermore, the late diastolic velocity at both corners of the MA had significant positive relations with LA dP/dt (r = 0.67, p < 0.01) and LA relaxation (r = 0.73, p < 0.01) but an inverse correlation with LV end-diastolic pressure (r = -0.53, p = 0.01).

CONCLUSIONS

Left ventricular relaxation, minimal pressure and preload determine Ea while late diastolic velocity determinants include LA dP/dt, LA relaxation and LV end-diastolic pressure.

Changes in left ventricular filling and left atrial function six months after nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy

OBJECTIVES

The purpose of this study was to evaluate changes in left ventricular (LV) filling, left atrial (LA) volumes and function six months after nonsurgical septal reduction therapy (NSRT) for hypertrophic obstructive cardiomyopathy (HOCM).

BACKGROUND

Patients with HOCM frequently have enlarged left atria, which predisposes them to atrial fibrillation. Nonsurgical septal reduction therapy results in significant reduction in left ventricular outflow tract (LVOT) obstruction and symptomatic improvement. However, its effect on LV passive filling volume, LA volumes and function is not yet known.

METHODS

Thirty patients with HOCM underwent treadmill exercise testing as well as 2-dimensional and Doppler echocardiography before and six months after NSRT. Data included clinical status, exercise duration, LVOT gradient, mitral regurgitant (MR) volume, LV pre-A pressure and LA volumes. Left atrial ejection force and kinetic energy (KE) were computed noninvasively and were compared with 12 age-matched, normal subjects.

RESULTS

New York Heart Association (NYHA) class was lower and exercise duration was longer (p < 0.05) six months after NSRT. The LVOT gradient, MR volume and LV pre-A pressure were all significantly reduced. HOCM patients had larger atria, which had a higher ejection force and KE, compared with normal subjects (p < 0.01). After NSRT, LV passive filling volume increased (p < 0.01), whereas LA volumes, ejection force and KE decreased (p < 0.01). Reduction in LA maximal volume was positively related to changes in LV pre-A pressure (r = 0.8, p < 0.05) and MR volume (0.4, p < 0.05). Changes in LA ejection force were positively related to changes in LA pre-A volume (r = 0.7, p < 0.01) and KE (r = 0.81, p < 0.01). The increase in exercise duration paralleled the increase in LV passive filling volume (r = 0.85, p < 0.05).

CONCLUSIONS

Nonsurgical septal reduction therapy results in an increase in LV passive filling volume and a reduction in LA size, ejection force and KE.

Changes in left ventricular diastolic function 6 months after nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy

BACKGROUND

Nonsurgical septal reduction therapy (NSRT) decreases left ventricular outflow tract (LVOT) gradient and improves symptoms in patients with hypertrophic obstructive cardiomyopathy (HOCM). NSRT effects on LV/left ventricular diastolic function are currently unknown.

METHODS AND RESULTS

HOCM patients (n=29) had Doppler echocardiography at baseline and 6 months after NSRT to evaluate changes in LV volume, pre-A-wave pressure, early diastolic mitral annulus velocity (Ea) by tissue Doppler, and tau. At 6 months, a significant reduction in LVOT gradient (from 53.6+/-15 to 6+/-5 mm Hg; P<0.001) was accompanied by improvement in exercise duration (from 284+/-147 to 408+/-178 seconds; P=0.04) and New York Health Association class (from III to I; P<0.001). Pre-A pressure (18+/-6 to 14+/-5 mm Hg; P<0.01) and tau (62+/-8 to 51+/-8 ms; P<0.01) decreased, whereas Ea (5.8+/-1.8 to 8+/-1.8 cml/s; P<0.01) and LV end-diastolic volume (117+/-16 to 130+/-22 mL; P<0.01) increased.

CONCLUSIONS

NSRT improves LV relaxation and compliance, which contributes to the symptomatic relief seen at 6 months.

Doppler estimation of left ventricular filling pressures in patients with hypertrophic cardiomyopathy

BACKGROUND

Conventional Doppler parameters are unreliable for estimating left ventricular (LV) filling pressures in hypertrophic cardiomyopathy (HCM). This study was undertaken to evaluate flow propagation velocity by color M-mode and early diastolic annular velocity (Ea) by tissue Doppler 2 new indices of LV relaxation, combined with mitral E velocity for estimation of filling pressures in HCM.

METHODS AND RESULTS

Thirty-five HCM patients (52+/-15 years) underwent LV catheterization simultaneously with 2-dimensional and Doppler echocardiography. Pulsed Doppler echocardiography of mitral and pulmonary venous flows was obtained along with flow propagation velocity and Ea. LV preA pressure had weak or no relations with mitral, pulmonary venous velocities and atrial volumes. In contrast, preA pressure related strongly to E velocity/flow propagation velocity (r=0.67; SEE=4) and E/Ea (r=0.76; SEE=3.4). In 17 patients with repeat measurements, preA pressure changes were well detected by measuring E velocity/flow propagation velocity (r=0.68; P=0.01) or E/Ea (r=0.8; P<0.001). PreA pressure estimation with these 2 methods was tested prospectively in 17 additional HCM patients with good results (E velocity/flow propagation velocity, r=0.76; E/Ea, r=0.82).

CONCLUSIONS

LV filling pressures can be estimated with reasonable accuracy in HCM patients by measuring E velocity/flow propagation velocity or E/Ea. These ratios also track changes in filling pressures.

Doppler estimation of left ventricular filling pressure in sinus tachycardia. A new application of tissue doppler imaging

BACKGROUND

Doppler echocardiography is frequently used to predict filling pressures in normal sinus rhythm, but it is unknown whether it can be applied in sinus tachycardia, with merging of E and A velocities. Tissue Doppler imaging (TDI) can record the mitral annular velocity. The early diastolic velocity (Ea) behaves as a relative load-independent index of left ventricular relaxation, which corrects the influence of relaxation on the transmitral E velocity.

METHODS AND RESULTS

We evaluated 100 patients 64+/-12 years old with simultaneous Doppler and invasive hemodynamics. Mitral inflow was classified into 3 patterns: complete merging of E and A velocities (pattern A), discernible velocities with A dominance (B), or E dominance (C). The Doppler data were analyzed at the mitral valve tips for E, acceleration and deceleration times of E, and isovolumic relaxation time. In patterns B and C, the A velocity, E/A ratio, and atrial filling fraction were derived. Pulmonary venous flow velocities were also measured, and TDI was used to acquire Ea and Aa. Weak significant relations were observed between pulmonary capillary wedge pressure (PCWP) and sole parameters of mitral flow, pulmonary venous flow, and annular measurements. These were better for patterns A and C. E/Ea ratio had the strongest relation to PCWP [r=0.86, PCWP=1.55+1.47(E/Ea)], irrespective of the pattern and ejection fraction. This equation was tested prospectively in 20 patients with sinus tachycardia. A strong relation was observed between catheter and Doppler PCWP (r=0.91), with a mean difference of 0.4+/-2.8 mm Hg.

CONCLUSIONS

The ratio of transmitral E velocity to Ea can be used to estimate PCWP with reasonable accuracy in sinus tachycardia, even with complete merging of E and A velocities.

Estimation of left and right ventricular filling pressures after heart transplantation by tissue Doppler imaging

Current Doppler methods have been unreliable in estimating filling pressures in heart transplants. Tissue Doppler imaging is a technique that permits evaluation of myocardial relaxation; combined with transvalvular E velocity, it could improve estimation of these pressures. To investigate this possibility, we evaluated 50 patients by right-sided cardiac catheterization and Doppler echocardiography simultaneously. Their mean +/-SD age was 53+/-15 years and the mean age of donor hearts was 30+/-12.5 years. The mitral E velocity was combined with the early myocardial relaxation (Ea) velocity by tissue Doppler at the lateral border of the mitral annulus. Likewise, the tricuspid E velocity was combined with Ea at the lateral corner of the tricuspid annulus. Mean wedge pressure related weakly to mitral inflow variables but strongly to E/Ea [r=0.8; wedge pressure=2.6+1.46(E/Ea)]. In 25 repeat right-sided cardiac catheterizations, changes in mean wedge pressure were well detected by Doppler, with a mean difference of -0.7+/-3 mm Hg. Mean right atrial pressure related weakly to routine tricuspid inflow variables but strongly to tricuspid E/Ea [r=0.79; n=38; right atrial pressure=1.76(E/Ea) - 3.7]. In 18 repeat right-sided cardiac catheterizations, changes in mean right atrial pressure were well detected by Doppler, with a mean difference of 0+/-3.45 mm Hg. Mean wedge pressure and mean right atrial pressure can be estimated in heart transplants with reasonable accuracy using the ratio of E/Ea. Furthermore, this method can accurately track changes in filling pressures.

Role of myocardial contrast echocardiography during nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy

OBJECTIVES

This study was undertaken to evaluate the ability of myocardial contrast echocardiography (MCE) to guide the targeted delivery of ethanol during nonsurgical septal reduction therapy (NSRT) and to assess the relation between the MCE risk area and infarct size determined by enzymatic and radionuclide methods.

BACKGROUND

NSRT with intracoronary ethanol is a new promising treatment for patients with hypertrophic obstructive cardiomyopathy (HOCM). Proper localization and quantification of the septal infarct before ethanol injection are highly desirable. MCE can provide accurate delineation of the vascular territory of the coronary arteries.

METHODS

Twenty-nine patients with HOCM and maximal medical therapy underwent NSRT. The left ventricular outflow tract (LVOT) gradient by Doppler echocardiography at baseline was 53 +/- 16 mm Hg (mean +/- SD). Before NSRT, MCE was performed in all patients with intracoronary sonicated albumin (Albunex). Diluted sonicated albumin (Albunex) was selectively injected into the septal perforator arteries during simultaneous transthoracic imaging. Immediately after MCE, ethanol was injected into the same vessel. Plasma total creatine kinase (CK), total CK-MB fraction and CK-MB fraction subforms were measured at baseline and serially for 36 h.

RESULTS

LVOT gradient decreased to 12 +/- 6 mm Hg (p < 0.001) after NSRT. Accurate mapping of the vascular beds of the septal perforators was successfully attained in all patients by MCE. Furthermore, the MCE risk area correlated well with peak CK (r = 0.79, p < 0.001). Six weeks after NSRT, 23 patients underwent myocardial perfusion studies performed with single-photon emission computed tomography (SPECT). Mean SPECT septal perfusion defect size involved 9.5 +/- 6% of the left ventricle and correlated well with MCE area (r = 0.7), with no statistically significant difference between the risk area estimated by MCE and that by SPECT.

CONCLUSIONS

Estimation of the size of the septal vascular territory with MCE is accurate, safe and feasible in essentially all patients during NSRT. MCE can delineate the perfusion bed of the septal perforators and can predict the infarct size that follows ethanol injection.

Doppler tissue imaging: a noninvasive technique for evaluation of left ventricular relaxation and estimation of filling pressures

OBJECTIVES

This investigation was designed 1) to assess whether the early diastolic velocity of the mitral annulus (Ea) obtained with Doppler tissue imaging (DTI) behaves as a preload-independent index of left ventricular (LV) relaxation; and 2) to evaluate the relation of the mitral E/Ea ratio to LV filling pressures.

BACKGROUND

Recent observations suggest that Ea is an index of LV relaxation that is less influenced by LV filling pressures.

METHODS

One hundred twenty-five study subjects were classified into three groups according to mitral E/A ratio, LV ejection fraction (LVEF) and clinical symptoms: 34 asymptomatic subjects with a normal LVEF and an E/A ratio > or =1; 40 with a normal LVEF, an E/A ratio <1 and no heart failure symptoms (impaired relaxation [IR]); and 51 with heart failure symptoms and an E/A ratio >1 (pseudonormal [PN]). Ea was derived from the lateral border of the annulus. A subset of 60 patients had invasive measurement of pulmonary capillary wedge pressure (PCWP) simultaneous with Doppler echocardiographic DTI.

RESULTS

Ea was reduced in the IR and PN groups compared with the group of normal subjects: 5.8 +/- 1.5 and 5.2 +/- 1.4 vs. 12 +/- 2.8 cm/s, respectively (p < 0.001). Mean PCWP (20 +/- 8 mm Hg) related weakly to mitral E (r = 0.68) but not to Ea. The E/Ea ratio related well to PCWP (r = 0.87; PCWP = 1.24 [E/Ea] + 1.9), with a difference between Doppler and catheter measurements of 0.1 +/- 3.8 mm Hg.

CONCLUSIONS

Ea behaves as a preload-independent index of LV relaxation. Mitral E velocity, corrected for the influence of relaxation (i.e., the E/Ea ratio), relates well to mean PCWP and may be used to estimate LV filling pressures.