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At least 217 records · Page 12Linked to original sources

PubMed2003

Arm-trunk coordination in the absence of proprioception.

During trunk-assisted reaching to targets placed within arm's length, the influence of trunk motion on the hand trajectory is compensated for by changes in the arm configuration. The role of proprioception in this compensation was investigated by analyzing the movements of 2 deafferented and 12 healthy subjects. Subjects reached to remembered targets (placed approximately 80 degrees ipsilateral or approximately 45 degrees contralateral to the sagittal midline) with an active forward movement of the trunk produced by hip flexion. In 40% of randomly selected trials, trunk motion was mechanically blocked. No visual feedback was provided during the experiment. The hand trajectory and velocity profiles of healthy subjects remained invariant whether or not the trunk was blocked. The invariance was achieved by changes in arm interjoint coordination that, for reaches toward the ipsilateral target, started as early as 50 ms after the perturbation. Both deafferented subjects exhibited considerable, though incomplete, compensation for the effects of the perturbation. Compensation was more successful for reaches to the ipsilateral target. Both deafferented subjects showed invariance between conditions (unobstructed or blocked trunk motion) in their hand paths to the ipsilateral target, and one did to the contralateral target. For the other deafferented subject, hand paths in the two types of trials began to deviate after about 50% into the movement, because of excessive elbow extension. In movements to the ipsilateral target, when deafferented subjects compensated successfully, the changes in arm joint angles were initiated as early as 50 ms after the trunk perturbation, similar to healthy subjects. Although the deafferented subjects showed less than ideal compensatory control, they compensated to a remarkably large extent given their complete loss of proprioception. The presence of partial compensation in the absence of vision and proprioception points to the likelihood that not only proprioception but also vestibulospinal pathways help mediate this compensation.

Adaptation, Physiological↗

PubMed1999

Preparatory trunk motion accompanies rapid upper limb movement.

Evaluation of trunk movements, trunk muscle activation, intra-abdominal pressure and displacement of centres of pressure and mass was undertaken to determine whether trunk orientation is a controlled variable prior to and during rapid bilateral movement of the upper limbs. Standing subjects performed rapid bilateral symmetrical upper limb movements in three directions (flexion, abduction and extension). The results indicated a small (0.4-3.3 degrees) but consistent initial angular displacement between the segments of the trunk in a direction opposite to that produced by the reactive moments resulting from limb movement. Phasic activation of superficial trunk muscles was consistent with this pattern of preparatory motion and with the direction of motion of the centre of mass. In contrast, activation of the deep abdominal muscles was independent of the direction of limb motion, suggesting a non-direction specific contribution to spinal stability. The results support the opinion that feedforward postural responses result in trunk movements, and that orientation of the trunk and centre of mass are both controlled variables in relation to rapid limb movements.

Abdominal Muscles↗

PubMed2002

Greater trunk muscle torque reduces postmenopausal bone loss at the spine independently of age, body size, and vitamin D receptor genotype in Japanese women.

Bone mineral density (BMD) is affected by muscle strength. Recently, vitamin D receptor (VDR) genotype was reported to affect muscle strength as well as BMD in Caucasian women. The aim of this study was to evaluate independent effects of muscle strength of the trunk on BMD at the spine and its change over time in Japanese women. We followed 119 healthy postmenopausal women for 4 years and determined the change in BMD at the spine by dual energy X-ray absorptiometry. Isometric peak torque and isokinetic concentric and eccentric peak torque of the trunk flexors and extensors were measured. The VDR genotype was determined by the PCR-RFLP method based on Apa I and Taq I endonuclease digestions defining the absence/existence of the restriction sites as A/a and T/t, respectively. The subjects were 60.1 +/- 6.6 years old, had 0.808 +/- 0.159 g/cm2 of BMD at baseline. The mean annual change in BMD (delta BMD) was -5.6 +/- 10.4 mg/cm2 during the follow-up period. The VDR genotype, defined by Taq I enzyme, significantly related to BMD at baseline and delta BMD showing that the subjects with genotype TT had the lowest BMD at baseline and lost bone most rapidly. However, its effect on muscle strength was not significant. All the trunk muscle strength indices showed significant positive effects on delta BMD, that is, the effects in increasing the gain and reducing the loss of BMD, after controlling for the effects of age, body size and the VDR genotype. The eccentric trunk extensor torque had a significant positive effect on delta BMD in a dose-dependent manner. The effect of this torque was the greatest among all the muscle indices. The net effect of the trunk extensor torque on delta BMD was greater than that of the VDR genotype. The trunk muscle strength was suggested to affect BMD change independently of age, body size, and the VDR genotype. Exercise programs to increase the strength of the trunk muscles would be beneficial for the prevention of osteoporosis regardless of the VDR genotypes.

Absorptiometry, Photon↗

PubMed2002

Can increased intra-abdominal pressure in humans be decoupled from trunk muscle co-contraction during steady state isometric exertions?

The purpose of the present study was to investigate whether increased intra-abdominal pressure (IAP) can be achieved without elevating the overall trunk muscle co-contraction that causes increased spine compression force. Ten subjects performed isometric trunk flexion, extension, and lateral bending exertions while generating 0%, 40% and 80% of their maximal IAP or while co-contracting trunk muscles without consciously raising IAP. An additional three subjects performed a variety of ramp IAP, co-contraction and isometric exertion tasks while holding their breaths and while exhaling. An 18 degree-of-freedom, electromyogram (EMG)-assisted biomechanical model was used to quantify trunk muscle co-contraction with calculations of spine compression force and stability. Spine stability and compression force increased proportionally with increased IAP regardless of whether the subjects intentionally generated IAP or consciously avoided it. This increase was accomplished with significantly greater co-contraction of 12 major trunk muscles. The EMG activation of all muscles was highly correlated with IAP and intra-thoracic pressure (ITP) ( r from 0.59 to 0.95). Activity of the thoracic erector spinae correlated the best with ITP ( r=0.81), which in turn was correlated with IAP ( r=0.91). It was not possible to co-contract trunk muscles without generating IAP and ITP, or conversely to generate IAP without trunk muscle co-contraction and increased ITP.

Abdominal Cavity↗

PubMed2005

Coordination of head and trunk accelerations during walking.

The purpose of this study was to investigate the relationship between oscillatory dynamics of the head and trunk in each plane of motion during walking. Head and trunk accelerations of ten healthy subjects (age: 23 +/- 4 years) were measured in the vertical (VT), anterior-posterior (AP) and mediolateral (ML) directions using a pair of tri-axial accelerometers. All subjects performed five walking trials along a level 20 m walkway at their preferred gait velocity (1.30 +/- 0.15 m s(-1)). Acceleration data were analysed using power spectral, harmonic and regularity measures. Results indicated that: (1) oscillations of the head were smoother, with a greater proportion of power at lower frequencies than oscillations of the trunk, (2) differences in power spectral properties between the head and trunk were most pronounced in the ML direction, (3) coupling between VT-AP, VT-ML, and AP-ML accelerations were greater for the head than trunk, and (4) for both segments, the weakest coupling was observed for AP-ML acceleration relations. Overall, the results of this study suggest that accelerations of the head are significantly attenuated, and more tightly controlled, compared to accelerations of the lower trunk. This attenuation process was particularly evident for the ML direction, whereby head accelerations showed the greatest differences compared to ML accelerations at the trunk.

Acceleration↗

PubMed1998

Back extensor and psoas muscle cross-sectional area, prior physical training, and trunk muscle strength--a longitudinal study in adolescent girls.

The association between physical training, low back extensor (erector spinae plus multifidus muscles) and psoas muscle cross-sectional areas (CSA) and strength characteristics of trunk extension and flexion were studied in adolescent girls. A group of athletes (n = 49) (age range 13.7-16.3 years) consisting of gymnasts, figure skaters and ballet dancers was age-matched with non-athletes (n = 17) who acted as a sedentary control group. The CSA of psoas muscles and multifidus plus erector spinae muscles were measured from lumbar axial images by magnetic resonance imaging. Maximal trunk extension and flexion forces were measured in a standing position using a dynamometer and trunk musculature endurance was evaluated using static holding tests. When CSA were adjusted with body mass, the athletes showed significantly greater CSA in both muscles studied (psoas P < 0.001; erector spinae plus multifidus P < 0.05) than the non-athletes. The athletes also had a greater absolute psoas muscle CSA (P < 0.01) and trunk flexion force (P < 0.01) compared to the controls. When the forces were expressed relative to body mass, the athletes were superior both in trunk flexion (P < 0.001) and extension (P < 0.001). There was a significant correlation between muscle CSA and strength parameters, but the force per muscle CSA did not differ significantly between the athletes and the non-athletes. In addition, the athletes showed a better body mass adjusted muscle endurance in trunk flexion (P < 0.05) than the non-athletes. Our study indicated that regular physical training enhances trunk musculature hypertrophy, force and endurance in adolescent girls, and that there is an association between muscle CSA and strength parameters.

Adolescent↗

PubMed2005

Factors underlying the perturbation resistance of the trunk in the first part of a lifting movement.

In the first part of lifting movements, the trunk movement is surprisingly resistant to perturbations. This study examined which factors contribute to this perturbation resistance of the trunk during lifting. Three possible mechanisms were studied: force-length-velocity characteristics of muscles, the momentum of the trunk as well as the effect of passive extending of the elbows. A forward dynamics modelling and simulation approach was adopted with two different input signals: (1) stimulation of Hill-type muscles versus (2) net joint moments. Experimental data collected during an unperturbed lifting movement were used as a reference, which a simulated lifting movement had to resemble. Subsequently, the simulated lifting movement was perturbed by applying 10 kg extra mass at the wrist (both before and after lift-off and with/without a fixed elbow), without modifying the input signals. The momentum of the trunk appeared to be insufficient to explain the perturbation resistance of trunk movements as found experimentally. In addition to the momentum of the trunk, the force-length-velocity characteristics of the muscles are necessary to account for the observed perturbation resistance. Initial extension of the elbow due to the mass perturbation delayed the propagation of the load to the shoulder. However, this delay is reduced due to the impedance at the elbow provided by the characteristics of muscles spanning the elbow. So, the force-length-velocity characteristics of the muscles spanning the elbow joint increase the perturbation at the trunk.

Biomechanical Phenomena↗

PubMed2002

The effect of the Relton-Hall operative frame on trunk deformity in adolescent idiopathic scoliosis.

The prone operative position affects the geometry of the scoliotic spine. However, the literature provides little information concerning the effect of operative position on the scoliotic trunk geometry. This study compared the trunk deformity of 31 adolescent idiopathic scoliosis patients in two standardized positions: standing and prone on a Relton-Hall frame. The geometry of the trunk was assessed using 11 magnetic sensors placed on anatomical landmarks. Eight geometric indices of the trunk were compared using paired Student t-tests (alpha=0.01). The transverse rotation of shoulders, the coronal rotation of shoulders, the lateral shift of C7 with respect to S1, and the thoracic and lumbar angles of trunk rotation assessed in the operative position did not show any significant change compared to the standing position. Therefore, operative positioning using the Relton-Hall frame did not lead to an overall reduction in the scoliotic trunk deformity. Modifications to the Relton-Hall frame are required for optimal presurgical correction of the scoliotic trunk deformity.

Adolescent↗

PubMed2004

A non-randomized clinical control trial of Harrison mirror image methods for correcting trunk list (lateral translations of the thoracic cage) in patients with chronic low back pain.

Spinal trunk list is a common occurrence in clinical practice, but few conservative methods of spinal rehabilitation have been reported. This study is a non-randomized clinical control trial of 63 consecutive retrospective subjects undergoing spinal rehabilitation and 23 prospective volunteer controls. All subjects presented with lateral thoracic-cage-translation posture (trunk list) and chronic low back pain. Initial and follow-up numerical pain rating scales (NRS) and AP lumbar radiographs were obtained after a mean of 11.5 weeks of care (average of 36 visits) for the treatment group and after a mean of 37.5 weeks for the control group. The radiographs were digitized and analyzed for a horizontal displacement of T12 from the second sacral tubercle, verticality of the lumbar spine at the sacral base, and any dextro/levo angle at mid-lumbar spine. Treatment subjects received the Harrison mirror image postural correction methods, which included an opposite trunk-list exercise and a new method of opposite trunk-list traction. Control subjects did not receive spinal rehabilitation therapy, but rather self-managed their back pain. For the treatment group, there were statistically significant improvements (approximately 50%) in all radiographic measurements and a decrease in pain intensity (NRS: 3.0 to 0.8). For the control group, no significant radiographic and NRS differences were found, except in trunk-list displacement of T12 to S1, worsened by 2.4 mm. Mirror image (opposite posture) postural corrective exercises and a new method of trunk-list traction resulted in 50% reduction in trunk list and were associated with nearly resolved pain intensity in this patient population. The findings warrant further study in the conservative treatment of chronic low back pain and spinal disorders.

Adult↗

PubMed1996

Measures of paraspinal muscle performance do not predict initial trunk kinematics after tripping.

The ability to limit the trunk flexion associated with an anteriorly directed trip is a determinant of successful recovery of recovering postural stability and is subservient to rapidly detecting and correcting the imposed trunk flexion in the available time. This experiment tested the hypothesis that subjects demonstrating greater eccentric trunk/hip extension strength, faster voluntary reaction times, shorter automatic response latencies, and larger automatic activation amplitudes of the paraspinal muscles, would demonstrate less trunk flexion following a trip. An isokinetic protocol was used to obtain measures of trunk extension strength, response latencies, and activation amplitudes. Motion analysis methods were used to quantify trunk kinematics during the positioning phase of recovery following an induced trip. Statistically significant and functionally meaningful relationships between eccentric strength of the trunk/hip extensors, voluntary-reaction time, automatic reaction time, activation amplitudes and trunk kinematics failed to emerge. Thus, although automatic and voluntary paraspinal muscle responses have the potential to limit trunk flexion during the positioning phase of recovery, the task may be achieved through intersegmental factors or other muscular sources such as the gluteus maximus and hamstrings.

Accidental Falls↗

PubMed2004

Likelihood of left main coronary artery compression based on pulmonary trunk diameter in patients with pulmonary hypertension.

PURPOSE: In patients with pulmonary hypertension, extrinsic compression of the left main coronary artery by a dilated pulmonary trunk may cause angina, left ventricular ischemia, and sudden death. We assessed coronary artery compression in relation to pulmonary trunk diameter and other demographic, echocardiographic, hemodynamic, and scintigraphic variables. METHODS: Thirty-six patients (aged 15 to 86 years) with pulmonary hypertension, either idiopathic or associated with congenital heart disease, were enrolled. Left main coronary artery compression was defined angiographically as > or =50% obstruction associated with downward displacement of the vessel. Pulmonary trunk and aortic diameters were measured by transthoracic echocardiography. RESULTS: Twenty-six patients had angina, of whom 7 had left coronary artery compression. Compression was related to pulmonary trunk diameter (P = 0.002) and to the ratio of pulmonary trunk diameter to aortic diameter (P = 0.02). Compression was not seen at pulmonary artery diameters <40 mm; among 19 patients with values > or =40 mm, the rate was 37%. Similarly, compression did not occur at pulmonary trunk to aortic diameter ratios <1.21; among 27 patients with ratios > or =1.21, the rate was 26%. CONCLUSION: In pulmonary hypertension, noninvasive measurement of pulmonary trunk diameter may be helpful in determining the likelihood of left coronary artery compression and in selecting patients for diagnostic coronary angiography.

Adolescent↗

PubMed2005

Endurance times of trunk muscles in male intercollegiate rowers in Hong Kong.

OBJECTIVES: To establish isometric endurance times of trunk muscles and their ratios in a group of healthy intercollegiate rowers in Hong Kong for clinical assessment reference, and to compare the trunk endurance profile of the rowers in the current study with that of nonrowers in another study. DESIGN: Isometric endurance times were measured in 4 different positions in a cross-sectional manner. A subset of 5 subjects was tested 3 times 2 days and 1 week apart to evaluate reliability. SETTING: Sports medicine department of a national sports institute. PARTICIPANTS: Thirty-two subjects selected from a group of 42 male intercollegiate rowers reported to have more than 6 months of rowing experience and without history of low back pain. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Trunk muscle endurance times in seconds and ratios of endurance times normalized to that of the extensor muscle. RESULTS: The trunk flexor (mean +/- standard deviation, 176.56+/-88.58 s) had the best endurance times among all the trunk muscles tested (extensor mean, 114.28+/-34.62 s; left lateral flexor mean, 94.53+/-32.97 s; right lateral flexor mean, 98.13+/-41.38 s). No significant difference was found between the left and right lateral flexors (P<.05). The lateral flexor and the flexor endurance times were 85% and 154% of that of the extensor, respectively. The testing protocol in this group of rowers showed good to excellent reliability (intraclass correlation coefficient range, .76-.93). CONCLUSIONS: Intercollegiate rowers in Hong Kong have better endurance in their trunk flexor than the extensor; the lateral flexors are of similar endurance capacity. These findings are different from the endurance profile reported for nonrowers in a previous study. Such differences should be considered when evaluating trunk endurance times in rowers for rehabilitation and training.

Abdominal Muscles↗

PubMed2004

Electromyographic activity of voluntarily activated trunk flexor and extensor muscles in post-stroke hemiparetic subjects.

OBJECTIVE: To study the EMG activity of selected trunk muscles during self-initiated voluntary flexion and extension of the trunk in post-stroke hemiparetic subjects, and to compare measurement results to corresponding findings in control subjects. METHODS: Using a sample of 50 patients and 30 control subjects, bilateral EMG activity of the rectus abdominis (RA) and external oblique (EO) muscles was studied during direct trunk flexion, and activity of the lumbar erector spinae (ES) and latissimus dorsi (LD) was studied during straight trunk extension. Variables of timing, magnitude, and temporal synchronization between muscle activity on the paretic and non-paretic sides of the body in the patient group were compared with the same measurements taken from the left and right sides of the body in the control group. RESULTS: Activity of the RA and LD muscles on the affected side of the body was reduced and delayed relative to the unaffected side in the patients and relative to the control subjects. Some deterioration was also observed in the function of the EO muscle, whereas the lumbar ES displayed normal activity on both sides of the body. Trunk velocity during both flexion and extension was slower in the patients than in the controls. CONCLUSIONS: Despite the existence of ipsilateral as well as contralateral higher inputs to axial and to a lesser extent also to more lateral trunk muscles, the function of the superficial abdominal muscles and of the LD muscle is adversely affected by a contralateral stroke. Conversely, the lumbar ES, which can be categorized as local trunk extensors, seem to normally fulfill their anti-gravitational task on both sides of the body.

Abdominal Muscles↗

PubMed2005

Interstride trunk acceleration variability but not step width variability can differentiate between fit and frail older adults.

Variability of gait may be regarded as a sign of adaptability and thus a requirement for successful locomotion, or as a sign of impaired balance control. In this study we examined the role of step width variability (SWV) and interstride trunk acceleration variability in two groups of fit and frail old people. We investigated the association of these measures and how they differentiated the two groups. We examined 33 fit older adults (mean age 73 years, S.D. 3.3 years) and 32 frail old people (mean age 80 years, S.D. 4.0 years). Subjects performed timed walking at different speeds ranging from very slow to very fast. SWV was measured from footprints. Trunk accelerations were registered by a triaxial accelerometer and interstride trunk acceleration variability assessed by an unbiased autocorrelation procedure. All measures were normalized to a walking speed of 0.9 m/s to avoid the confounding effect of gait speed on speed dependent gait parameters. SWV demonstrated low association with the trunk variability measures, and did not differ between groups. The frail group had lower mediolateral (P=0.015), but higher vertical (P=0.015) and anteroposterior (P<0.02) trunk variability than the fit group. Trunk variability classified 80% of the subjects correctly into their respective group (sensitivity=0.75, specificity=0.85). The findings are compatible with a notion that mediolateral interstride trunk variability represents a different aspect of motor control than variability in the direction of propulsion.

Acceleration↗

PubMed2006

Criterion validity of 3D trunk accelerations to assess external work and power in able-bodied gait.

Evaluative quantification of gait disorder minimizing time-consuming and cost-intensive laboratory installations remains a challenging task in movement analysis. We examined the criterion validity of global gait mechanics assessed by trunk accelerometry. Eight female and four male volunteer subjects (mean age, 27.5 years; S.D., 5.1 years; weight, 68.7+/-11.3kg; height, 1.74+/-0.08m) without gait dysfunction participated in the study. They walked barefoot over two adjacent force-platforms at self-selected speeds. In addition to ground reaction forces, vertical, anterior-posterior and medio-lateral accelerations of the trunk were simultaneously measured by means of a light tri-axial accelerometer. Mean acceleration cycles of the trunk and the body centre of mass were calculated. Acceleration vectors were integrated twice to obtain velocity and displacement vectors of the trunk and the centre of mass, respectively. Temporal boundaries of right and left functional stance phases were defined by the two intermediate moments between maximum anterior-posterior velocity and minimal vertical displacement. Cross-correlations of the kinematics of the trunk and the centre of mass were determined. External work and corresponding symmetry indicators were computed for both methods. Centre of mass anterior-posterior displacement lagged behind the trunk by 3.5% of the gait cycle. External power correlated highly (r>0.82) between the trunk model and the centre of mass. Work correlated moderately high (r=0.77) between the two methods. Work and power asymmetry indexes correlated moderately high (r>0.64). Our findings suggest that accelerometry has the potential to assess functional kinematics and energy-related outcomes in large cohorts.

Acceleration↗

PubMed2005

Age-related differences in head and trunk coordination during walking.

The purpose of this study was to examine the effect of ageing on the pattern and structure of head and trunk accelerations during walking. Head and trunk accelerations of young (n=8; mean=23 years, SD=4 years) and elderly (n=8; mean=74 years, SD=3 years) individuals were measured using triaxial accelerometers while performing preferred speed walking. Accelerations were examined using power-spectral analysis and measures of signal smoothness, regularity and coupling. No differences in walking speed or signal regularity were detected between age groups. Compared to the young participants, the elderly had (1) a greater proportion of signal power above 6 Hz for the trunk, (2) a smaller difference in signal smoothness between the trunk and head, (3) less signal smoothness in the mediolateral direction, and (4) a greater degree of directional coupling for the head compared to the trunk. Overall these results suggest that the pattern of head accelerations was relatively unaffected by age, and that both age groups achieved similar levels of head stability despite differences in trunk acceleration characteristics. The manner in which head stability was achieved differed between age groups, with the elderly employing an upper body coordination strategy that enhanced coupling between acceleration directions of the head compared to the trunk. The findings of this study also suggest that an absence of age-related differences in signal complexity at one level of postural system, combined with differences at another level, may provide information about the way in which the motor system prioritises postural control during gait.

Adult↗

PubMed2006

A method for quantifying directional strength and motor control of the trunk.

We describe a new apparatus for studying trunk motor control. Quasi-isometric trunk forces are exerted in any horizontal direction while seated, with or without the pelvis stabilised. Trunk force magnitude and direction are measured using a novel transducing system. In addition, reaction forces between the buttocks and the seat and between each foot and the ground are measured with three force plates. Twenty-four healthy subjects exerted maximal forces in eight directions, with and without pelvis fixation. Accuracy of trunk force measurements was assessed by comparing them with reaction force measurements. The agreement analysis showed a small mean bias of the new system of -3.0 N for force magnitude and 0.72 degrees for force direction. The trunk force measurement system was sensitive enough to detect effects of movement direction and pelvis fixation on maximum force magnitude. When subjects repeated the test at a later date there were no significant differences between the two sessions. In conclusion, the new device allows measurement of static and dynamic aspects of voluntary trunk activation in multiple directions while seated and provides reproducible measurements for application to longitudinal studies. The method should prove useful for quantifying deficits and recovery of trunk motor control following neurological damage.

Adult↗

PubMed2006

Trunk muscle endurance tests: reliability, and gender differences in athletes.

Adequate trunk muscle endurance may play an important role in injury-free performance among athletes. However, reliability of tests of isometric trunk muscle endurance in common use has not been clearly established and few studies have reported normative data for athletes. This study first examined intra-rater and inter-rater reliability of the side bridge endurance test and a test of trunk flexor endurance in a group of non-athletes, then measured performance of a group of elite athletes on tests of trunk muscle endurance commonly used in the clinic. The side bridge endurance test and the trunk flexor endurance test were found to have high intra-rater and inter-rater reliability, albeit with relatively large standard error of measurement (S.E.M.) values. In contrast with previous studies of non-athletes, male athletes had equivalent holding times on the Biering-Sørensen trunk extensor endurance test to those of female athletes. However, female athletes had significantly lower holding times on the side bridge endurance tests than their male counterparts. The implication of the significant difference in endurance performance between male and female athletes in some muscle groups but not others is that testing and training of trunk muscle endurance should be 'multidirectional' for all athletes who aim to optimise performance and minimise injury risk.

Adolescent↗