Kinematic patterns associated with accuracy of the drop punt kick in Australian Football.

Research into the kinematics of movement associated with the accuracy of the drop punt kick in Australian Football has been limited. The aim of this study was to examine pelvic and lower limb kinematics during the performance of a drop punt kick, in order to identify factors associated with accurate kicking performance. Ten professional Australian Football League (AFL) players performed 20 drop punt kicks towards a target situated 15m away, using their preferred leg. A three-dimensional motion analysis system was used to record the kicking motion from heel contact of the support limb through to ball contact. The subjects were divided into an accurate group (> or =50% accuracy; n=5) and an inaccurate group (<50% accuracy; n=5) based on target hit rate. Kinematic profiles for both kicking and support limbs were compared between the two groups. Results showed that the accurate group had significantly greater hip flexion in both limbs and greater knee flexion in the support limb throughout the kicking movement. The accurate group also had significantly greater anterior pelvic tilt at heel contact (accurate 20.8 degrees ; inaccurate 12.7 degrees ). These data show that kinematic differences in lower limb joint angles may be related to kicking accuracy.

Effect of vertical jumping on the medial gastrocnemius and soleus muscles of rats.

Ten rats were trained to perform approximately 30 jumps/day, 5 days/wk for at least 8 wk, from a force platform that enabled the number and height of jumps to be quantified. There was considerable variation in height jumped during an activity session both within and between rats. The two highest-jumping rats attained a displacement of center of mass of approximately 30 cm, estimated to be approximately 67% of the maximum attainable. The two lowest-jumping rats jumped to approximately 30% of the estimated maximum. The activity was described as "habitual activity" rather than "training" because there were no significant increases in the height of jumping by any rat over the period of activity. The isometric properties of medial gastrocnemius (MG) and soleus muscles were studied in terminal experiments on anesthetised rats. Five significant effects on MG were evoked by this pattern of exercise ("habituation"): 1) a 15-18% increase in force at frequencies of stimulation between 60 and 150 Hz and a 15% increase in maximum tetanic tension to 14.9 N, 2) a 3% increase in the maximum rate of rise of tetanic force to 3.4% of maximum tetanic tension per millisecond, 3) an increase in fatigability expressed as a smaller fatigue index in active rats (33%) than in controls (58%), 4) a decrease of 4% in the percentage of type IIa muscle fibers, and 5) an increase of 6% in the percentage of type II fibers that could not be classified with certainty as IIa or IIb.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of gait patterns between the offspring of people with medial tibiofemoral osteoarthritis and normal controls.

OBJECTIVES: The aim of this study was to explore the contribution of biomechanical factors to the development and progression of knee osteoarthritis (OA) by investigating whether the offspring of subjects with medial tibiomfemoral OA demonstrate gait abnormalities in the absence of OA. METHODS: Three-dimensional gait analyses were performed on 9 offspring of people with medial tibiofemoral OA and 9 age, gender and Body Mass Index (BMI) matched individuals with no parental history of knee OA. External knee adduction, extension and flexion moments, as well as the magnitude of foot rotation during early stance were compared between the groups. RESULTS: The offspring of people with medial tibiofemoral OA walked with less external rotation at the foot than control subjects during early stance (4.5 degrees versus 13.5 degrees, p < 0.01). There were no significant differences between groups for the peak knee adduction moments (dominant leg, p = 0.49; non-dominant leg, p = 0.70) or peak knee extension moments (dominant leg, p = 0.46; non-dominant leg, p = 0.48). Moreover, there was no difference between groups for the knee flexion moment occurring when the force adducting the knee was greatest (dominant leg, p = 0.35; non-dominant leg, p = 0.33). CONCLUSIONS: Although the offspring of people with medial tibiofemoral OA walked with less external foot rotation than the control subjects during early stance, whether this increases their risk of developing knee OA is yet to be determined.

Mechanical resonance of the human body during voluntary oscillations about the ankle joint.

Viscoelastic models of the musculoskeletal system suggest resonant frequencies of oscillatory movement at which maximal output is realized with minimal energy expenditure. To investigate this, resonance at the human ankle joint was explored by comparing predicted and experimental gain/frequency and phase frequency functions. These functions were predicted from viscous (B) and elastic (K) coefficients of ankle extensors which were determined from the damped sinusoidal force produced after landing with muscles in sustained contraction (B = 3986 kg/s, K = 31,898 kg/s2). Experimental input/output functions were determined from Fourier analysis of force (output) and rectified, filtered EMG (input) obtained during voluntary sinusoidal oscillations of ground reaction force of a specified magnitude and frequency. Correlations between predicted and experimental functions were significant (p less than 0.02) in four of five subjects. The average resonant frequency was 3.33 +/- 0.15 Hz. The mechanical properties of muscle are considered to be as important as the nervous system in determining the choice of both the movement pattern and the strategy which is adopted in response to changing conditions.

The effect of training on physical therapists' ability to apply specified forces of palpation.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate whether postgraduate physical therapy students studying manipulation could learn to accurately produce specific forces during palpation of an intervertebral joint. SUBJECTS: The 12 subjects (7 female, 5 male), aged 26 to 36 years (X = 29.5, SD = 2.9), had each completed a 4-year degree course in physical therapy and had worked between 3 and 10 years in clinical practice. All subjects were enrolled in a 12-month postgraduate manipulative therapy diploma course. METHODS: Subjects in the experimental group (n = 6) trained to apply specific forces of 1, 5, 10, 15, 20, and 25 kiloponds using bathroom scales. They practiced for 10 minutes per day for 30 days. Their ability to produce these forces on command was measured using a force platform as they applied posteroanterior passive accessory intervertebral joint movements to the lumbar spine of the healthy subjects. This testing was done prior to training (pretest), immediately after training (posttest), and 1 month following cessation of training (retention test). The control group subjects (n = 6) had no training with scales but were also students of the postgraduate manipulative physical therapy course. RESULTS: In comparison with the control group, the experimentally trained group showed reduced error in force production both immediately after training and 1 month later. This improvement was significant for the retention test. For the retention test, the experimental group subjects were also tested on the trained task (ie, their ability to apply specific forces to the scales). They developed higher levels of accuracy than did the control group. CONCLUSION AND DISCUSSION: Experimental training, therefore, was an effective addition to normal training, suggesting that therapists can learn to quantify applied forces, with significant implications for communication and evaluation of joint behavior.

The reliability of selected techniques in clinical arthrometrics.

A number of studies which have examined reliability of spinal assessment procedures in manual therapy are reviewed. The tests examined were Passive Accessory Intervertebral Movements, Passive Physiological Intervertebral Movements, Straight Leg Raise and Forward Flexion. In general, tests of pain were found to be much more reproducible than tests of compliance. Straight Leg Raise and Forward Flexion tests were consistently more reliable than the Passive Intervertebral Movement tests. Possible explanations for these findings are advanced. The role of tests of compliance based on passive intervertebral movements in clinical decision-making may need to be re-examined. An appendix on reliability theory is included for the uninitiated reader.

novel Award First Prize Paper. Orthotic management of plantar pressure and pain in rheumatoid arthritis.

OBJECTIVE: To investigate the effectiveness of foot orthoses in the management of plantar pressure and pain in subjects with rheumatoid arthritis. DESIGN: A repeated measures study in which the independent variable was orthosis design. Dependent variables, including pressure, gait and pain parameters, were examined using analysis of variance and correlation statistics. BACKGROUND: The aim of orthotic management of the rheumatoid foot is to relieve metatarsalgia through the reduction of metatarsal head pressure. Few studies have investigated the relative effectiveness of different orthosis designs. To date, no studies have examined the relationship between plantar pressure and second metatarsal head pain in rheumatoid arthritis subjects. METHODS: Twelve rheumatoid arthritis subjects with foot involvement and second metatarsal head pain were tested. Four styles of foot orthosis (prefabricated, standard custom moulded, custom with metatarsal bar, custom with metatarsal dome) were compared to a shoe only control. An EMED Pedar system was used to measure plantar pressure during repeated trials of comfortable cadence walking and quiet standing. Reports of subjective pain were recorded for each orthosis as were orthosis preferences. RESULTS: All orthoses significantly reduced pressure beneath the first and second metatarsal heads compared to the shoes only control. The custom moulded orthosis with metatarsal dome was the most effective orthosis for reducing subjective ratings of pain. A significant correlation (r=0.562) was found between ratings of pain and average pressure beneath the second metatarsal head. CONCLUSIONS: Results from this study suggest that average pressure measurement may be a useful indicator in the management of metatarsalgia in RA. Further study is required to improve understanding of the relationship between rheumatoid foot mechanics and pain. RELEVANCE: Appropriate foot orthosis design can substantially improve comfort in RA patients with symptomatic feet. A custom moulded foot orthosis incorporating a metatarsal dome was the most effective design for subjects with painful second metatarsal heads. Foot pressure measurement technology can be a useful adjunct to research and clinical management of the painful rheumatoid foot.

Video assessment of rearfoot movements during walking: a reliability study.

OBJECTIVE: Rearfoot motion, particularly rearfoot pronation, has been associated with many foot and leg pathologies. The assessment of abnormal rearfoot pronation frequently involves the use of video assessment in both clinical and research settings, but the reliability of this assessment has not been addressed. DESIGN: In this study, 14 participants were videotaped during walking. Five clinicians individually viewed the recordings on two separate occasions and assessed whether the participant's rearfoot motion was abnormal. SETTING: University Gait Analysis Laboratory. PATIENTS OR OTHER PARTICIPANTS: Patients from the university's podiatry clinic were assessed for rearfoot motion by five experienced clinicians. INTERVENTION: Because this was a reliability study, no intervention was undertaken. MAIN OUTCOME MEASURES: Clinicians were asked to assess the videotape of the patients walking and indicate on a 3-point scale if they considered the person to be abnormally pronating. Retest and intertester results were compared. RESULTS: The results indicated that there was poor intertester agreement (kappa = .19). Retest agreement, while slightly higher, varied from poor to fair (kappa = -.12 to kappa = 59). CONCLUSIONS: Although video recordings have been thought to enhance reliability of assessment of rearfoot motion, the results indicated that the exclusive use of video recordings in the assessment of motion of the rearfoot was not reliable.

Exercise induced acute renal failure in an athlete.

After a strenuous indoor competition, a 24 year old male 400 meter runner experienced severe back pain followed by three days of nausea and vomiting. This led to hospital admission with oliguria, serum creatinine of 12.6 mg%, and BUN of 72 mg%. Peritoneal dialysis was given for 96 hours and was discontinued when the diuretic phase developed. Myoglobinuria was suspected, but all tests for it were negative. Mechanisms of acute tubular necrosis are reviewed, noting predisposing factors-dehydration, acidosis, and hypoxia-which were present in this clinical case. Ischemia due to markedly reduced renal blood flow secondary to mass sympathetic discharge, dehydration and metabolic acidosis could cause sufficient tissue damage to trigger acute renal failure in the presence of myoglobinemia. Active fluid replacement in athletic training and competition is stressed as a preventive feature.

Postural control following inversion injuries of the ankle.

Postural control was investigated following unilateral inversion injury of the ankle in 24 trained and 24 untrained subjects at least 8 weeks following injury and following resumption of high-speed activities. The two groups differed in the practice of balance exercises in one-legged stance during rehabilitation. Using a force platform the variability of the mediolateral force signal was used to quantify steadiness as each subject stood in one-legged stance with the eyes open and closed on the injured and noninjured legs. A three way analysis of variance showed that for the untrained subjects postural steadiness was significantly worse on the injured leg than the noninjured leg both with eyes open (p < .05) and closed (p < .05). No postural deficit was found on the injured leg of the trained subjects with eyes open or closed (p > .05). It is strongly recommended that rehabilitation following inversion injury of the ankle include balance retraining to minimize the risk of further injury.

Force platform measures for evaluating postural control: reliability and validity.

The reliability and validity of force platform measures used to evaluate steadiness of stance were investigated in a group of 28 healthy subjects in four basic stance positions: two-legged, step, tandem, and one-legged stance. In each stance position five indices of steadiness were obtained by sampling the three orthogonal force signals and the two horizontal center of pressure (CP) signals for 15 seconds and computing the standard deviation for each signal. Correlations between these five indices derived from the force platform showed that the relationship between force and CP measures was generally weak. In fact, approximately 40% of the correlations were nonsignificant (p greater than .05). There was a strong trend for the retest reliability of force measures to be higher than the retest reliability of CP measures. The difference was statistically significant in three stances (p less than .05). Force measures were more sensitive than CP measures in discriminating the changes in steadiness which resulted from alterations to the base of support in the four stance positions. Factor analysis showed that force measures were the best predictors of steadiness in each stance, but the axis varied according to the particular stance condition. Although it may be appropriate in some cases to justify the choice of measure according to the nature of the clinical condition being studied, these results provide a rationale for choosing force measures in preference to CP measures on the fundamental principles of reliability and validity.

Steadiness in one-legged stance: development of a reliable force-platform testing procedure.

Postural steadiness in one-legged stance has potential for evaluation of unilateral injuries and disorders, but any test protocol must be demonstrated to be both feasible and reliable. A testing protocol for using a force platform to measure steadiness in one-legged stance with eyes opened and eyes closed was successfully developed, and its within-session retest reliability was investigated in a group of 24 young, healthy subjects. Strategies were used to minimize the loss of data for trials in which the subjects incurred significant loss of balance from the one-legged position. The performance scores examined were the standard deviation of the three orthogonal force components and the two horizontal center of pressure (CP) coordinates averaged over four consecutive five-second trials. The retest coefficients for all test conditions were substantially improved compared with testing protocols reported earlier. Retest reliability was higher for performance scores based on force measures than for performance scores based on CP measures. The difference was statistically significant in two of the stances, with a similar trend in the other two stances. Further, factor analysis showed that force measures were the best predictors of steadiness in one-legged stance. Analysis of variance failed to detect any systematic effect for leg preference or laterality on steadiness in one-legged stance with eyes opened or eyes closed in the healthy subjects with no history of injury (p greater than .05). The test protocol described enables the development of clinical or experimental trials with repeated-measures design using the subject's nonaffected leg as a control.

Maximum voluntary weight-bearing by the affected and unaffected legs in standing following stroke.

OBJECTIVE: To compare stroke patients to control subjects for ability to transfer body weight onto the affected and unaffected leg in standing; to investigate intra-session reliability. DESIGN: Comparative clinical study conducted within a single session. BACKGROUND: There is a paucity of quantitative data about maximum voluntary weight-bearing in patients during rehabilitation following stroke. METHODS: A Kistler force platform was used to quantify maximum amount of body weight transferred to a single limb in the lateral and forward directions during weight-shifting. Twelve control subjects matched by gender and age (median 64 years) were compared to 12 inpatient stroke patients after a median of 37 days post-onset. RESULTS: The median score for control subjects was approximately 95% of body weight to each leg in both directions. In contrast, stroke patients transferred less body weight (P<0.01) to the affected leg (65.5% lateral; 54.9% forward) and also to the unaffected leg (85.0% lateral; 80.1% forward). For the stroke patients, transfer of body weight was more challenging in the forward direction than the lateral direction on the affected leg (P<0.05). Relative to individual differences in the stroke group, error due to the repeated measurement process was low. CONCLUSION: The testing procedure was found to discriminate between stroke patients and control patients and had high retest reliability within a single session.

Comparison of subjective and objective measures of movement performance in children with cerebral palsy.

This study evaluated the use of accelerometry to measure the quality of movement in children with cerebral palsy. Accelerometer scores based on a previously described test were correlated with scores on a newly developed clinical test shown to be both valid and reliable. Low correlations were obtained between clinical test scores and accelerometer scores. Although the accelerometer test has been shown to be effective in distinguishing between able-bodied children and those with cerebral palsy, it is not sufficiently sensitive to distinguish between levels of movement quality in the latter population. The accelerometer may measure a different aspect of movement from that measured by the clinical test, and does not appear to be a valid test of the quality of movement in children with cerebral palsy.

Electrogoniometric feedback: its effect on genu recurvatum in stroke.

The purpose of this study was to determine the effect of combining electrogoniometric feedback with contemporary physical therapy procedures for treatment of genu recurvatum following stroke. Twenty-six patients suffering knee hyperextension resulting from cerebrovascular disorders were allocated to either a control group or an experimental group. Both groups received treatment for knee hyperextension during two consecutive phases. During phase I the control group received physical therapy and the experimental group received electrogoniometric feedback as an adjunct to physical therapy. In phase II both groups received physical therapy alone. Each phase lasted four weeks, during which time patients were treated 45 minutes daily, five days every week. Subjects in the experimental group showed greater reduction in knee hyperextension. This was particularly evident in phase II when the difference between groups for reduction in knee hyperextension reached statistical significance (U = 40, p = 0.011). These results suggest that the addition of electrogoniometric feedback to standard physical therapy enhanced the effectiveness of treatment for genu recurvatum in stroke.

Development of a clinical assessment of quality of movement for unilateral upper-limb function.

Eleven subjects with cerebral palsy were assessed both with the Melbourne Assessment and by four clinical experts. Comparison of their assessment ratings revealed that the Melbourne Assessment was strongly related to the clinical judgement of the experts. A further 20 subjects were administered the Melbourne Assessment and two occupational therapists scored each subject's performance from videotaped assessments with substantial inter-rater reliability (0.68); intra-rater agreement after two weeks was 0.80. The Melbourne Assessment may provide a satisfactory objective measure of the quality of upper-limb function.

Prediction of gait velocity in ambulatory stroke patients during rehabilitation.

OBJECTIVE: To quantify prediction of gait velocity in ambulatory stroke patients during rehabilitation. DESIGN: Single group (n = 42) at the beginning of rehabilitation (Test 1) and 8 weeks later (Test 2). SETTING: Inpatient rehabilitation. PATIENTS: Unilateral first stroke; informed consent; able to walk 10 meters. INDEPENDENT VARIABLES: Gait velocity at Test 1, age, time from stroke to Test 1, side of lesion, neglect. DEPENDENT VARIABLES: Gait velocity at Test 2, gait velocity change. RESULTS: The correlation between initial gait velocity and gait velocity outcome at Test 2 was of moderate strength (r2 = .62, p<.05). However, even at its lowest, the standard error of prediction for an individual patient was 9.4 m/min, with 95% confidence intervals extending over a range of 36.8 m/min. Age was a weak predictor of gait velocity at Test 2 (r2 = -.10, p<.05). Gait velocity change was poorly predicted. The only significant correlations were initial gait velocity (r2 = .10, p<.05) and age (r2 = .10, p<.05). CONCLUSION: While the prediction of gait velocity at Test 2 was of moderate strength on a group basis, the error surrounding predicted values of gait velocity for a single patient was relatively high, indicating that this simple approach was imprecise on an individual basis. The prediction of gait velocity change was poor. A wide range of change scores was possible for patients, irrespective of their gait velocity score on admission to rehabilitation.