Forward Trunk Research Articles

ASSOCIATION BETWEEN FITNESS, NUTRITIONAL STATUS AND ACADEMIC PERFORMANCE IN PHYSICAL EDUCATION STUDENTS

several studies demonstrated that regular physical exercise would impact positively on the academic performance of students. to determine the association between physical fitness, nutritional status and academic performance of students of Pedagogy in Physical Education from Temuco, Chile. the sample was selected on a non-probabilistic approach, which included 208 subjects (n = 153 women and n = 55 women). The variables studied were physical fitness (short Abs, long jump with feet together, forward trunk flexion, elbow flexion and extension and "course navette" test), nutritional status (BMI) and academic performance (classified as up and down the academic average). 87.5% of students have a satisfactory fitness and a BMI of 23.8 ± 2.9 kg/m2. The students with the best academic performance were those with the higher proportion of satisfactory physical condition (92.5 %). No association between academic performance and nutritional status was determined, but it was observed between low fitness and a great risk of low academic performance (OR = 2.8, 95% CI 1.0 to 8 1; p < 0.05). a relationship between academic achievement and physical fitness among students is observed, but no for the nutritional status and the academic performance.

The effect of self-paced speed and virtual reality on treadmill gait in children with cerebral palsy

Kinetic outcomes are an essential part of clinical gait analysis, and can be collected for many consecutive strides using instrumented treadmills. However, the validity of treadmill kinetic outcomes has not been demonstrated for children with cerebral palsy (CP). In this study we compared ground reaction forces (GRF), center of pressure, and hip, knee and ankle moments, powers and work, between overground (OG) and self-paced treadmill (TM) walking for 11 typically developing (TD) children and 9 children with spastic CP. Considerable differences were found in several outcome parameters. In TM, subjects demonstrated lower ankle power generation and more absorption, and increased hip moments and work. This shift from ankle to hip strategy was likely due to a more backward positioning of the hip and a slightly more forward trunk lean. In mediolateral direction, GRF and hip and knee joint moments were increased in TM due to wider step width. These findings indicate that kinetic data collected on a TM cannot be readily compared with OG data in TD children and children with CP, and that treadmill-specific normative data sets should be used when performing kinetic gait analysis on a treadmill.

Kinetic comparison of walking on a treadmill versus over ground in children with cerebral palsy

Kinetic outcomes are an essential part of clinical gait analysis, and can be collected for many consecutive strides using instrumented treadmills. However, the validity of treadmill kinetic outcomes has not been demonstrated for children with cerebral palsy (CP). In this study we compared ground reaction forces (GRF), center of pressure, and hip, knee and ankle moments, powers and work, between overground (OG) and self-paced treadmill (TM) walking for 11 typically developing (TD) children and 9 children with spastic CP. Considerable differences were found in several outcome parameters. In TM, subjects demonstrated lower ankle power generation and more absorption, and increased hip moments and work. This shift from ankle to hip strategy was likely due to a more backward positioning of the hip and a slightly more forward trunk lean. In mediolateral direction, GRF and hip and knee joint moments were increased in TM due to wider step width. These findings indicate that kinetic data collected on a TM cannot be readily compared with OG data in TD children and children with CP, and that treadmill-specific normative data sets should be used when performing kinetic gait analysis on a treadmill.

Mobility Assessments

While many organizations have adopted various forms of movement screens, designers of these assessment tools fail to understand the difference between skill and mobility. Numerous studies within the motor control and learning literature demonstrate how proper verbal instructions and demonstration enhance skill acquisition. The cumulative result of these studies reinforces the importance for movement screens to include instructional descriptions of test-items in a manner in which the results isolate skill from mobility. PURPOSE: To compare performance on a common movement screen with limited instructions and with instructions including verbal instruction, demonstration, and practice. METHODS: 22 individuals (14 males, 8 females; 22 ± 1.4 years) participated. Each participant performed three overhead squats under three different conditions: baseline with no instruction, instructions taken from the Functional Movement Screen (FMS), and instructions including demonstration, and practice (IDP). Whole body kinematics were recorded using a 12-camera motion capture system. Center of mass vertical displacement, ankle flexion, trunk forward lean, and bar to body distance were extracted. Differences between conditions were assessed using a one-way ANOVA. RESULTS: COM displacement was greater in IDP (0.45 ± 0.10m.) than FMS condition (0.32 ± 0.20m.; p = 0.003), but not different than baseline (0.39 ± 0.12m.; p = 0.047). Forward trunk lean was also greater in IDP (0.33 ± 0.65m.) than FMS condition (0.29 ± .096m.; p =0.013) but not different than baseline (0.30 ± 0.07m., p = 0.048). Ankle dorsiflexion was greater in IDP (21.33° ± 5.22) than FMS condition (17.62° ± 6.26; p = 0.01) but not different than baseline (20.94° ± 4.7; p = 0.035). Bar to body distance was not different between any conditions. CONCLUSION: The results of this study suggest that practitioners using movement screens to identify movement dysfunction strongly consider whether they are seeing actual dysfunction or a lack of movement skill.

Another day, another tennis coaching intervention, but does this one do what coaches purport?

A proficient serve is critical to successful tennis performance, and consequently coaches and players devote considerable time refining this stroke. In so doing, a wide variety of interventions are used or trialled, generally with very little empirical support. This study examined the efficacy of a commonly used service intervention, where players focus on exaggerating their finish (arabesque) position to promote specific changes in lower limb and trunk kinematics. The kinematics of eight high-performance junior players hitting flat serves were compared to the acute changes in kinematics elicited by the arabesque follow through position on serves using a 10-camera VICON MX motion analysis system. The significantly greater front (landing leg) hip flexion (p < 0.05) and forward trunk flexion (p < 0.05) confirmed the more exaggerated arabesque landing position following the arabesque instruction. The arabesque instruction resulted in increased frontal plane trunk range of motion and peak angular velocity in the forward swing, and increased leg drive during the drive phase. Practically, the results support the use of the arabesque instruction, effectively promoting the desired acute changes in trunk kinematics (i.e. increased frontal plane trunk rotation angular velocity) and leg drive (i.e. increased back knee extension angular velocity and front/back vertical hip velocity).

Influence of trunk posture on lower extremity energetics during running.

This study aimed to examine the influence of sagittal plane trunk posture on lower extremity energetics during running. Forty asymptomatic recreational runners (20 males and 20 females) ran overground at a speed of 3.4 m·s(-1). Sagittal plane trunk kinematics and lower extremity kinematics and energetics during the stance phase of running were computed. Subjects were dichotomized into high flexion (HF) and low flexion (LF) groups on the basis of the mean trunk flexion angle. The mean (±SD) trunk flexion angles of the HF and LF groups were 10.8° ± 2.2° and 3.6° ± 2.8°, respectively. When compared with the LF group, the HF group demonstrated significantly higher hip extensor energy generation (0.12 ± 0.06 vs 0.05 ± 0.04 J·kg(-1), P < 0.001) and lower knee extensor energy absorption (0.60 ± 0.14 vs 0.74 ± 0.09 J·kg(-1), P = 0.001) and generation (0.30 ± 0.05 vs 0.34 ± 0.06 J·kg(-1), P = 0.02). There was no significant group difference for the ankle plantarflexor energy absorption or generation (P > 0.05). Sagittal plane trunk flexion has a significant influence on hip and knee energetics during running. Increasing forward trunk lean during running may be used as a strategy to reduce knee loading without increasing the biomechanical demand at the ankle plantarflexors.

Revised NIOSH Lifting Equation May generate spine loads exceeding recommended limits

The 1991 NIOSH Lifting Equation (NLE) is widely used to assess the risk of injury to spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses the predictive equations developed based on a detailed trunk musculoskeletal biomechanical model to verify whether the RWL generates L5-S1 loads within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in some studies). Fifty lifting activities are simulated here to evaluate the RWL by the NLE and the L5-S1 loads by the predictive equations. In lifting activities involving moderate to large forward trunk flexion, the estimated RWL generates L5-S1 spine loads exceeding the recommended limits. The NIOSH vertical multiplier is the likely cause of this inadequacy; a revised multiplier accounting for the trunk flexion angle is hence needed. The use of a fixed 3400 N compression limit is also questioned. Relevance to industryErgonomist and occupational health practitioners are advised to use the NLE along with the predictive equations of the spine loads proposed in this study when evaluating the risk of injury to the spine in lifting activities particularly those involving moderate to large trunk flexion.

A neuroprosthesis for control of seated balance after spinal cord injury.

BackgroundA major desire of individuals with spinal cord injury (SCI) is the ability to maintain a stable trunk while in a seated position. Such stability is invaluable during many activities of daily living (ADL) such as regular work in the home and office environments, wheelchair propulsion and driving a vehicle. Functional neuromuscular stimulation (FNS) has the ability to restore function to paralyzed muscles by application of measured low-level currents to the nerves serving those muscles.MethodsA feedback control system for maintaining seated balance under external perturbations was designed and tested in individuals with thoracic and cervical level spinal cord injuries. The control system relied on a signal related to the tilt of the trunk from the vertical position (which varied between 1.0 ≡ erect posture and 0.0 ≡ most forward flexed posture) derived from a sensor fixed to the sternum to activate the user’s own hip and trunk extensor muscles via an implanted neuroprosthesis. A proportional-derivative controller modulated stimulation between trunk tilt values indicating deviation from the erect posture and maximum desired forward flexion. Tests were carried out with external perturbation forces set at 35%, 40% and 45% body-weight (BW) and maximal forward trunk tilt flexion thresholds set at 0.85, 0.75 and 0.70.ResultsPreliminary tests in a case series of five subjects show that the controller could maintain trunk stability in the sagittal plane for perturbations up to 45% of body weight and for flexion thresholds as low as 0.7. The mean settling time varied across subjects from 0.5(±0.4) and 2.0 (±1.1) seconds. Mean response time of the feedback control system varied from 393(±38) ms and 536(±84) ms across the cohort.ConclusionsThe results show the high potential for robust control of seated balance against nominal perturbations in individuals with spinal cord injury and indicates that trunk control with FNS is a promising intervention for individuals with SCI.

Trunk and shoulder kinematic and kinetic and electromyographic adaptations to slope increase during motorized treadmill propulsion among manual wheelchair users with a spinal cord injury.

The main objective was to quantify the effects of five different slopes on trunk and shoulder kinematics as well as shoulder kinetic and muscular demands during manual wheelchair (MWC) propulsion on a motorized treadmill. Eighteen participants with spinal cord injury propelled their MWC at a self-selected constant speed on a motorized treadmill set at different slopes (0°, 2.7°, 3.6°, 4.8°, and 7.1°). Trunk and upper limb movements were recorded with a motion analysis system. Net shoulder joint moments were computed with the forces applied to the handrims measured with an instrumented wheel. To quantify muscular demand, the electromyographic activity (EMG) of the pectoralis major (clavicular and sternal portions) and deltoid (anterior and posterior fibers) was recorded during the experimental tasks and normalized against maximum EMG values obtained during static contractions. Overall, forward trunk flexion and shoulder flexion increased as the slope became steeper, whereas shoulder flexion, adduction, and internal rotation moments along with the muscular demand also increased as the slope became steeper. The results confirm that forward trunk flexion and shoulder flexion movement amplitudes, along with shoulder mechanical and muscular demands, generally increase when the slope of the treadmill increases despite some similarities between the 2.7° to 3.6° and 3.6° to 4.8° slope increments.

Effects of forward trunk lean on hamstring muscle kinematics during sprinting

This study aimed to investigate the effects of forward trunk lean on hamstring muscle kinematics during sprinting. Eight male sprinters performed maximal-effort sprints in two trunk positions: forward lean and upright. A three-dimensional musculoskeletal model was used to compute the musculotendon lengths and velocity of the biceps femoris long head, semitendinosus, and semimembranosus muscles during the sprinting gait cycle. The musculotendon lengths of all the three hamstring muscles at foot strike and toe-off were significantly greater during the forward trunk lean sprint than during the upright trunk sprint. In addition, a positive peak musculotendon lengthening velocity was observed in the biceps femoris long head and semimembranosus muscles during the late stance phase, and musculotendon lengths at that instant were significantly greater during the forward trunk lean sprint than during the upright trunk sprint. The present study provides significant evidence that a potential for hamstring muscle strain injury involving forward trunk lean sprinting would exist during the stance phase. The results also indicate that the biceps femoris long head and semimembranosus muscles are stretched during forward trunk lean sprinting while contracting eccentrically in the late stance phase; thus, the elongation load on these muscles could be increased.

Manual handling: differences in perceived effort, success rate and kinematics between three different pushing techniques

This study examined the perceived effort, success rates and kinematics for three push strategies in a simulated lateral patient transfer (horizontal slide). Thirteen healthy subjects (four males) completed three repetition pushing loads of 6, 10 and 14 kg in random order; with a spontaneous push strategy, then with a straight-back bent-knees (squat) strategy and the preparatory pelvic movement (‘rockback’) strategy in random order. Perceived effort and kinematic parameters measured at the onset of movement and at maximum push excursion were compared between strategies and between loads with repeated measures ANOVA. The spontaneous and ‘rockback’ strategies achieved the pushing task with less perceived effort across all loads than the squat push (P < 0.001). Only 3/13 participants were successful on all attempts at pushing the 14 kg load using a squat strategy, which contrasted with 12/13 participants when the spontaneous strategy or the ‘rockback’ strategy was used. Forward movement of the pelvis and forward trunk inclination may be positively associated with lower perceived effort in the push task.Practitioner Summary: In a manual-handling task that simulated a lateral patient transfer (horizontal slide), perceived effort and success rates of three push strategies were compared. A straight-back bent-knees push (squat) strategy demonstrated greater perceived effort and lower success rates than a spontaneous push strategy, or a push strategy with preparatory ‘rockback’ pelvic movement.

Deficiencies in Pitching Biomechanics in Baseball Players With a History of Superior Labrum Anterior-Posterior Repair

Background: Baseball pitchers who undergo superior labrum anterior-posterior (SLAP) repair often have trouble returning to their previous level of performance. While the reason is often assumed to be diminished shoulder range of motion or other mechanical changes, differences in pitching biomechanics between baseball pitchers with a history of SLAP repair and pitchers with no injury history have not been studied previously. Hypothesis: The primary hypothesis was that compared with the control group, the SLAP group would exhibit compromised shoulder range of motion (external rotation and horizontal abduction) and internal rotation torque during pitching. Study Design: Controlled laboratory study. Methods: Pitching biomechanics were compared retrospectively between a group of 13 collegiate and professional pitchers with a history of a SLAP tear and a control group of 52 pitchers with no history of surgery; groups were matched by age, height, weight, and pitch velocity. Data were collected with an automated 3-dimensional motion analysis system while participants threw fastballs from the windup. Biomechanics of the shoulder (horizontal abduction and external rotation), elbow (flexion, extension velocity, and flexion torque), and body (stride length, shoulder horizontal adduction, and forward trunk tilt) were compared between the 2 groups. For each variable, a Student t test was used at an α level of .05. Results: Pitchers in the SLAP group exhibited significantly less shoulder horizontal abduction (10.0° ± 13.2° vs 21.0° ± 11.7°, respectively; P = .013) and shoulder external rotation (168.3° ± 12.7° vs 178.3° ± 7.3°, respectively; P = .016) than those in the control group. In addition, players in the SLAP group pitched with a more upright trunk, demonstrated by a less forward trunk tilt at the instant of ball release (30.2° ± 6.3° vs 34.4° ± 6.6°, respectively; P = .048). Conclusion: Pitchers with a history of SLAP repair produce less shoulder horizontal abduction, shoulder external rotation, and forward trunk tilt during pitching than do pitchers with no history of injury. Clinical Relevance: To facilitate normal pitching mechanics, shoulder external rotation and horizontal abduction at 90° should be primary objectives in surgical repair and rehabilitation after SLAP repair. In addition, pitchers should work with their pitching coaches to ensure proper forward trunk tilt.

Squatting Mechanics in People With and Without Anterior Cruciate Ligament Reconstruction

Background: Single-legged squat mechanics change after anterior cruciate ligament (ACL) reconstruction and rehabilitation, but it is unclear if changes in squat mechanics are graft specific. Purpose: To investigate graft differences in biomechanics of the knee, hip, and trunk during the single-legged squat in patients with ACL-reconstructed knees, determine if these factors were associated with deficits in knee extension moment, and determine if subjective knee function and squat biomechanics are related. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 106 individuals were grouped based on surgical status and graft type (51 control, 34 bone–patellar tendon–bone [BPTB], 21 ipsilateral semitendinosus and gracilis autograft [ISGA]). Motion capture interfaced with force plates was used to capture single-legged squat performance in the ACL reconstructed and dominant control limbs. Variables were captured at peak knee flexion. Results: Controls exhibited greater knee extension moment (P = .04), knee flexion (P = .002), and hip adduction angles (P = .04) compared with the reconstructed groups. The ISGA group demonstrated greater forward (P = .01) and lateral (P = .002) trunk flexion over the reconstructed limb. Summated extension moment did not differ between groups (P = .42). Knee extension moment was correlated with lateral trunk flexion (r = −0.31, P = .03) in the control group and knee flexion angle (r = −0.44, P = .04) in the ISGA group. Subjective knee function scores were correlated with lateral trunk flexion (r = −0.45, P = .008) in the BPTB group and with hip adduction angle (r = −0.46, P = .04) and hip extension moment (r = 0.48, P = .03) in the ISGA group. Conclusion: Knee and hip biomechanics were related to surgical status but not graft type. Increased forward and lateral trunk motion in the ISGA group may be a mechanism to protect the knee by minimizing motion during squatting or related to surgical selection bias. Secondary findings (summated extensor moments and correlations) most likely represent a strategy to shift the squat demands from the knee to the hip. Clinical Relevance: Clinicians should target these neuromuscular deficits during rehabilitation and training programs after ACL reconstruction.

Sagittal plane trunk posture influences patellofemoral joint stress during running.

Cross-sectional, repeated-measures. Objectives To examine the association between sagittal plane trunk posture and patellofemoral joint (PFJ) stress, and to determine whether modifying sagittal plane trunk posture influences PFJ stress during running. Patellofemoral pain is the most common injury among runners and is thought to be the result of elevated PFJ stress. While sagittal plane trunk posture has been shown to influence tibiofemoral joint mechanics, no study has examined the influence of trunk posture on PFJ kinetics. Twenty-four asymptomatic recreational runners (12 women, 12 men) ran overground at a speed of 3.4 m/s under 3 trunk-posture conditions: self-selected, flexed, and extended. Trunk and knee kinematics, ground reaction forces, and electromyographic signals from selected lower extremity muscles were obtained. A previously described PFJ biomechanical model was used to quantify PFJ stress. The mean ± SD trunk flexion angles under the self-selected, flexed, and extended running conditions were 7.3° ± 3.6°, 14.1° ± 4.8°, and 4.0° ± 3.9°, respectively. A significant inverse relationship was observed between mean trunk flexion angle and peak PFJ stress during the self-selected condition (r = -0.60, P = .002). Peak PFJ stress was significantly lower in the flexed condition (mean ± SD, 20.2 ± 3.4 MPa; P<.001) and significantly higher in the extended condition (23.1 ± 3.4 MPa; P<.001) compared to the self-selected condition (21.5 ± 3.2 MPa). Sagittal plane trunk posture has a significant influence on PFJ kinetics during running. Incorporation of a forward trunk lean may be an effective strategy to reduce PFJ stress during running.

Biomechanical analysis of low back load when sneezing

BackgroundAlthough sneezing is known to induce low back pain, there is no objective data of the load generated when sneezing. Moreover, the approaches often recommended for reducing low back pain, such as leaning with both hands against a wall, are not supported by objective evidence. MethodsParticipants were 12 healthy young men (mean age 23.25±1.54 years) with no history of spinal column pain or low back pain. Measurements were taken using a three-dimensional motion capture system and surface electromyograms in three experimental conditions: normal for sneezing, characterized by forward trunk inclination; stand, in which the body was deliberately maintained in an upright posture when sneezing; and table, in which the participants leaned with both hands on a table when sneezing. We analyzed and compared the intervertebral disk compressive force, low back moment, ground reaction force, trunk inclination angle, and co-contraction of the rectus abdominis and erector spinae muscles in the three conditions. FindingsThe intervertebral disk compressive force and ground reaction force were significantly lower in the stand and table conditions than in the normal condition. The co-contraction index value was significantly higher in the stand condition than in the normal and table conditions. InterpretationWhen sneezing, body posture in the stand or table condition can reduce load on the low back compared with body posture in the normal sneezing condition. Thus, placing both hands on a table or otherwise maintaining an upright body posture appears to be beneficial for reducing low back load when sneezing.

Evaluation of proximal joint kinematics and muscle strength following ACL reconstruction surgery in female athletes.

Despite the intense focus on outcomes following an anterior cruciate ligament (ACL) reconstruction, it is not yet known whether unresolved abnormal hip and trunk neuromuscular control exists. The purpose of this study was to compare trunk and hip kinematics during running, hip abductor and external rotator strength, and trunk control between females who had undergone an ACL reconstruction and healthy control participants. We compared 20 ACL reconstructed females to 20 healthy individuals, measuring abduction and external rotation strength, a trunk control test, and performed an instrumented gait evaluation during running. Comparisons between groups were made for non-sagittal peak hip angles, forward trunk lean, trunk ipsilateral lean at initial contact, trunk control and hip abduction, and external rotation strength. We found no significant differences in hip abduction (p = 0.25), hip external rotation strength (p = 0.63), peak hip adduction (p = 0.11) or hip internal rotation angle (p = 0.47). The ACL group did have a significantly greater ipsilateral trunk lean (p = 0.028), forward lean (p = 0.004), and had higher errors on the trunk stability test (p = 0.007). We found significant differences in trunk control, suggesting further attention should be devoted to this component of rehabilitation.

Comparison of Landing Biomechanics Between Male and Female Dancers and Athletes, Part 2

Background: Fatigue is strongly linked to an increased risk of injuries, including anterior cruciate ligament (ACL) ruptures. Part 1 of this study identified differences in the biomechanics of landing from a jump between dancers and team athletes, particularly female athletes, which may explain the epidemiological differences in ACL injuries between dancers and team athletes and the lack of a sex disparity within dancers. However, it is not known if these biomechanical variables change differently between team athletes and dancers in the face of fatigue. Purpose/Hypothesis: The purpose of this study was to compare dancers’ and team athletes’ resistance to fatigue and its effect on the biomechanics of single-legged drop landings. The primary hypotheses were that dancers may be more resistant than team athletes to the onset of fatigue and/or may have different biomechanical responses than athletes in landing tasks once fatigue has been achieved. Study Design: Controlled laboratory study. Methods: Kinematics and kinetics were recorded as 40 elite modern and ballet dancers (20 men and 20 women) and 40 team sport athletes (20 men and 20 women; National Collegiate Athletic Association Division I-III) performed single-legged drop landings from a 30-cm platform before and after a fatigue protocol consisting of step-ups and vertical jumps. Unfatigued and fatigued joint kinematics and kinetics were compared between groups and sexes with multivariate analyses of variance, followed by pairwise t tests as appropriate. Results: Dancers took longer (P = .023) than team athletes to reach a similar state of fatigue. Multiple kinetic (eg, increased peak knee valgus moment; P < .001) and kinematic (eg, increased lateral and forward trunk flexion; P < .001 and P = .002, respectively) parameters of landing changed with fatigue, such that both fatigued dancers and athletes landed with mechanics that were more at risk for ACL injuries as compared with before fatigue. Conclusion: Dancers took significantly longer to reach fatigue than team athletes. Female athletes consistently exhibited landing patterns associated with a risk for ACL injuries when compared with the other 3 groups. Fatigue changed landing mechanics similarly in both dancers and athletes, such that all groups landed with worse alignment after being fatigued. Clinical Relevance: Dancers are more resistant to lower extremity fatigue than athletes, and this may partially explain the lower incidence of ACL injuries in both male and female dancers compared to team athletes. The extensive training in landing technique and daily practice that dancers undergo from a young age may be responsible for the higher levels of endurance.

Unusual Case of Levodopa-Responsive Camptocormia in a Patient With Negative Dopamine Transporter Scan and Normal DYT 5 Gene

To describe an unusual case of camptocormia responding to levodopa. We present a case of camptocormia with a sustained excellent response to levodopa in a patient with negative dopamine transporter and no DYT 5 genetic mutations. We present a 52-year-old man with 2 years' history of progressive camptocormia, with nearly normal posture while standing and forward trunk flexion close to 90 degrees after walking for less than a minute. His posture completely resolved in the supine position. There were no pyramidal or extrapyramidal signs or dystonia in other locations. Family history was noncontributory except 1 paternal aunt with Parkinson disease. There was no history of antidopaminergic exposure. Workup, including brain, cervical, thoracic, and lumbar spine magnetic resonance imaging and paraspinal muscle electromyography, was unremarkable. Serum ceruloplasmin level was normal. Genetic testing for dopa-responsive dystonia, including GTP cyclohydrolase 1 (GCH 1) and tyrosine hydroxylase (TH) gene mutations (sequencing and deletion), was negative. DYT 6 (THAP1) gene mutation was not found, and dopamine transporter scan imaging obtained 4 years after onset of symptoms was normal. The patient has had an excellent response to levodopa sustained for the past 2 years. Levodopa should be considered in camptocormia even when not associated with neurodegenerative parkinsonism or DYT 5 gene mutation.

Compensatory Strategies for Muscle Weakness During Stair Ascent in Subjects With Total Knee Arthroplasty

Subjects with total knee arthroplasty (TKA) exhibit decreased quadriceps and hamstring strength. This may bring about greater relative effort or compensatory strategies to reduce knee joint moments in daily activities. To study gait and map out the resource capacity, knee muscle strength was assessed by maximal voluntary concentric contractions, and whole body kinematics and root mean square (RMS) electromyography (EMG) of vastus lateralis and semitendinosus were recorded during stair ascent in 23 unilateral TKA-subjects ~19months post-operation, and in 23 healthy controls. Muscle strength and gait velocity were lower in the TKA group, but no significant group differences were found in RMS EMG or forward trunk lean. The results suggest that reduced walking velocity sufficiently compensated for reduced knee muscle strength.

The effect of trunk flexion on lower-limb kinetics of able-bodied gait

Able-bodied individuals spontaneously adopt crouch gait when walking with induced anterior trunk flexion, but the effect of this adaptation on lower-limb kinetics is unknown. Sustained forward trunk displacement during walking can greatly alter body center-of-mass location and necessitate a motor control response to maintain upright balance. Understanding this response may provide insight into the biomechanical demands on the lower-limb joints of spinal pathology that alter trunk alignment (e.g., flatback). The purpose of this study was to determine the effect of sustained trunk flexion on lower-limb kinetics in able-bodied gait, facilitating understanding of the effects of spinal pathologies. Subjects walked with three postures: 0° (normal upright), 25±7°, and 50±7° trunk flexion. With increased trunk flexion, decreased peak ankle plantar flexor moments were observed with increased energy absorption during stance. Sustained knee flexion during mid- and terminal stance decreased knee flexor moments, but energy absorption/generation remained unchanged across postures. Increased trunk flexion placed significant demand on the hip extensors, thus increasing peak hip extensor moments and energy generation. The direct relationship between trunk flexion and energy absorption/generation at the ankle and hip, respectively, suggest increased muscular demand during gait. These findings on able-bodied subjects might shed light on muscular demands associated with individuals having pathology-induced positive sagittal spine balance.