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At least 19 recordsLinked to original sources
PubMed2003

Microtensile bond strength of a total-etch 3-step, total-etch 2-step, self-etch 2-step, and a self-etch 1-step dentin bonding system through 15-month water storage.

PURPOSE: To evaluate dentin bond durability using current dentin adhesive resin bonding approaches over a 15-month period of water storage. MATERIALS AND METHODS: Forty-four extracted human molars were polished with 600-grit SiC papers exposing occlusal dentin, and randomly distributed into four adhesive groups: total-etch 3-step (TE3) (Scotchbond Multi-Purpose, 3M ESPE), total-etch 2-step (TE2) (Single Bond, 3M ESPE), self-etch 2-step (SE2) (Clearfil SE Bond, Kuraray), and a self-etch 1-step (SE1) (Prompt L-Pop, 3M ESPE). A resin composite crown was incrementally formed and light cured to approximately 6 mm in height. Microtensile specimens were fabricated and stored in distilled water containing 0.5% chloramine T and tensile tested at 1 mm/min after 1, 6, and 15 months. The debond pathway was recorded as either involving the substrate or joint using scanning electron microscopy. SAS software was used to compute Weibull parameters and distributions, Log-rank and Wilcoxon tests were used for comparison of survival curves over time for each adhesive system and between adhesive systems. RESULTS: The TE2 was significantly weaker than TE3 and SE2 after 1 and 6 months of storage, but all three systems were equivalent after 15 months of storage. The SE1 system could not be tested due to 58 of 65 specimens failing during specimen preparation. Failure modes were observed to be dependent upon adhesive system, with only the total-etch 2-step system demonstrating an increasing involvement in the adhesive joint over time. CONCLUSION: Although differences in bond strength were observed across adhesive systems up to 6 months of storage, no differences were noted at 15 months. This may represent common degradative mechanisms.

Acid Etching, Dental↗
PubMed2004

Reproducibility of plantar pressure measurements in patients with chronic arthritis: a comparison of one-step, two-step, and three-step protocols and an estimate of the number of measurements required.

BACKGROUND: Plantar pressure measurement may be a helpful evaluation tool in patients with foot complaints. Determination of dynamic pressure distribution under the foot may give information regarding gait, progress of disorders, and the effect of treatment. However, for these measurements to have clinical application, reproducibility, consistency, and accuracy must be ascertained. We compared the reproducibility of measurements among one-step, two-step, and three-step protocols for data collection in patients with arthritis. In addition, the number of measurements needed for a consistent average was determined for the protocol that was found to be the most reproducible. METHODS: Twenty patients with foot complaints secondary to arthritis participated in the study. Each patient was tested with a pressure platform system using two of the three testing protocols. Reproducibility of contact time and maximal peak pressure were assessed. Intraclass Correlation Coefficients (ICC) were calculated for measurement results among protocols. In stage two of the study, the number of measurements needed for a consistent average was determined by calculating the first three measurements, the first five measurements, and then all seven measurements for both feet. ICC of three, five, and seven measurements were compared. The two-step protocol (13 patients), which was found in stage one of the study to be the most reproducible, was used for this determination. RESULTS: Reproducibility was found to be reasonable or good for all three measurement protocols. The mean values of contact time for the one-step protocol were found to be higher than the mean values of contact time for the two-step or three-step protocols in both feet. The differences between the one-step and three-step protocols were statistically significant for the left foot only. The mean peak pressure did not show statistically-significant differences among the three protocols. The one-step and three-step protocols were not used for stage two of the study. Using the two-step protocol, three measurements were found to be sufficient for obtaining a consistent average. CONCLUSIONS: The results of our study indicated that the one-step, two-step, and three-step protocols of collecting plantar pressure measurements in patients with foot complaints secondary to chronic arthritis were all similar. However, the use of the two-step protocol is recommended over the one-step and three-step protocols; the one-step protocol produced a longer stance phase that did not resemble normal walking and when comparing the two-step and three-step protocols, the two-step protocol was less time consuming and less strenuous for patients with painful feet.

Adolescent↗
PubMed2005

A comparison of the 1-step, 2-step, and 3-step protocols for obtaining barefoot plantar pressure data in the diabetic neuropathic foot.

BACKGROUND: Barefoot plantar pressure measurements are routinely used in the risk evaluation for ulceration in diabetic patients with neuropathy. The aim was to compare three step-protocols commonly used for pressure assessment in these patients. METHODS: Dynamic barefoot plantar pressures were measured in 14 diabetic neuropathic patients (vibration perception threshold >35 V) contacting a pressure platform on the first, second or third step after gait initiation. Ten repeated trials per step-protocol were collected. The 3-step protocol was regarded the reference protocol. Peak pressure, pressure-time integral and contact time were calculated for each of six anatomical foot regions. Intraclass correlation coefficients (ICC) were calculated to assess reliability in each protocol. FINDINGS: Regional peak pressures and pressure-time integrals were not significantly different between protocols. Contact time was significantly different in the heel region between the 1-step and 3-step protocol only (P<0.05). Intraclass correlation coefficients for the maximum 10 repeated trials were high (>0.87) and similar between protocols. Reliable estimates (ICC>0.85) of peak pressure were achieved with three repeated trials in the 2-step protocol, and four in the other two; for pressure-time integral these numbers were 7 (1-step), 4 (2-step), and 5 trials (3-step). INTERPRETATION: Barefoot plantar pressures in the diabetic neuropathic foot can be assessed in a reproducible manner with any of the step-protocols used. For this purpose, the 1-step and 2-step protocols prove to be valid methods. A 2-step protocol requires the least amount of repeated trials for obtaining reliable pressure data and may be recommended for assessment of these patients.

Biomechanical Phenomena↗
PubMed2004

Step width variability, but not step length variability or step time variability, discriminates gait of healthy young and older adults during treadmill locomotion.

The variability of spatial and temporal step kinematics have separately been shown to prospectively predict falls by older adults. However, the published literature has not addressed the relative importance of the information related to locomotion control contributed by variability of spatial variables, temporal variables, or both. We conducted a post hoc analysis to determine the extent to which the variability of spatial and temporal step kinematics are independent descriptors of locomotion control in healthy young and older adults. A second purpose of the analysis was to establish the extent to which treadmill walking mimics overground walking using a benchmark for step kinematics. Eighteen young adults and 12 older adults walked at a self-selected velocity on an instrumented treadmill from which step length variability, step width variability and step time variability were computed. Stepwise discriminant analysis correctly classified group membership of 70 percent of the 30 subjects (i.e., young or older adult) using only step width variability (p=0.037, Wilk's lamda=0.854). Step width variability was 70+/-57 percent larger than step length variability (p<0.001). This relationship was similar to that of the benchmark established for overground locomotion. The results suggest that for healthy younger and older adults step width variability is a more meaningful descriptor of locomotion control than step length variability and step time variability. Given the potential clinical impact, further systematic study and improvement of the methods and technology for acquiring step kinematic data are warranted.

Adult↗
PubMed2006

Relationships among subcomponents of the USMLE Step 2 Clinical Skills Examination, the Step 1, and the Step 2 Clinical Knowledge Examinations.

BACKGROUND: This research examined relationships between and among scores from the United States Medical Licensing Examination (USMLE) Step 1, Step 2 Clinical Knowledge (CK), and subcomponents of the Step 2 Clinical Skills (CS) examination. METHOD: Correlations and failure rates were produced for first-time takers who tested during the first year of Step 2 CS Examination administration (June 2004 to July 2005). RESULTS: True-score correlations were high between patient note (PN) and data gathering (DG), moderate between communication and interpersonal skills and DG, and low between the remaining score pairs. There was little overlap between examinees failing Step 2 CK and the different components of Step 2 CS. CONCLUSION: Results suggest that combining DG and PN scores into a single composite score is reasonable and that relatively little redundancy exists between Step 2 CK and CS scores.

Clinical Competence↗
PubMed2005

Two-step mechanism of photodamage to photosystem II: step 1 occurs at the oxygen-evolving complex and step 2 occurs at the photochemical reaction center.

Under strong light, photosystem II (PSII) of oxygenic photosynthetic organisms is inactivated, and this phenomenon is called photoinhibition. In a widely accepted model, photoinhibition is induced by excess light energy, which is absorbed by chlorophyll but not utilized in photosynthesis. Using monochromatic light from the Okazaki Large Spectrograph and thylakoid membranes from Thermosynechococcus elongatus, we observed that UV and blue light inactivated the oxygen-evolving complex much faster than the photochemical reaction center of PSII. These observations suggested that the light-induced damage was associated with a UV- and blue light-absorbing center in the oxygen-evolving complex of PSII. The action spectrum of the primary event in photodamage to PSII revealed the strong effects of UV and blue light and differed considerably from the absorption spectra of chlorophyll and thylakoid membranes. By contrast to the photoinduced inactivation of the oxygen-evolving complex in untreated thylakoid membranes, red light efficiently induced inactivation of the PSII reaction center in Tris-treated thylakoid membranes, and the action spectrum resembled the absorption spectrum of chlorophyll. Our observations suggest that photodamage to PSII occurs in two steps. Step 1 is the light-induced inactivation of the oxygen-evolving complex. Step 2, occurring after step 1 is complete, is the inactivation of the PSII reaction center by light absorbed by chlorophyll. We confirmed our model by illumination of untreated thylakoid membranes with blue and UV light, which inactivated the oxygen-evolving complex, and then with red light, which inactivated the photochemical reaction center.

Cyanobacteria↗
PubMed2005

Extension of a one-step self-etch adhesive into a multi-step adhesive.

UNLABELLED: One-step self-etch adhesives are undoubtedly the most user-friendly adhesives, but have been associated with lower bonding effectiveness as compared to two-step and three-step adhesives. Conversion of a one-step self-etch system into a two-step self-etch adhesive by adding a bonding step, or into a three-step etch&rinse adhesive by adding a beforehand etching step and a bonding step might be tempting in order to improve bond strength. OBJECTIVES: The objective of this study was to investigate whether adding application steps influences the bond strength of a one-step self-etch adhesive. METHODS: In this study, the bonding effectiveness of two experimental one-step self-etch adhesives and three different commercial adhesives to enamel and dentin was determined using a micro-tensile bond-strength protocol. This procedure was repeated for the experimental adhesives transformed into two-step self-etch and three-step etch&rinse adhesives. In addition, their interaction with tooth tissue was investigated using TEM and Feg-SEM. RESULTS: Transforming a one-step into a two-step self-etch adhesive did improve the bond strength to enamel and dentin, though not significantly. By adding a preceding etching step, the bond strength to enamel was significantly improved, but that to dentin was decreased considerably. The latter must be attributed to hampered resin infiltration of the one-step self-etch adhesive within the relatively deeply exposed collagen fibril network. SIGNIFICANCE: Additional application of a hydrophobic bonding agent slightly improved bonding effectiveness. Adding a preceding etching step is beneficial for enamel but should be avoided for dentin as this will decrease bond strengths, and may even jeopardize the bonding durability.

Acetone↗
PubMed2001

Elderly subjects' ability to recover balance with a single backward step associates with body configuration at step contact.

BACKGROUND: In the event of a slip or trip, one's ability to recover a stable upright stance by stepping should depend on (a) the configuration of the body at the instant of step contact and (b) the forces generated between the foot and ground during step contact. In this study, we tested whether these two variables associate with elderly subjects' ability to recover balance by taking a single backward step after sudden release from an inclined position. METHODS: Twenty-six community-dwelling subjects (12 women, 14 men) of mean age 75+/-4 (SD) years each underwent five trials in which they were suddenly released from a backward inclination of 7 degrees and instructed to "recover balance with a single step." Body segment motions and foot contact forces were analyzed to determine step contact times, stepping angles, body lean angles at step contact, and the magnitudes and times (after step contact) of peak foot-floor contact forces and peak sagittal-plane torques at the ankle, knee, and hip of the stepping leg. RESULTS: Fifty percent of subjects were predominantly single steppers (successful at recovering with a single step in greater than three of five trials), 27% were multiple steppers (successful in less than two of five trials), and 23% were mixed response steppers (successful in two of five or three of five trials). Recovery style associated with the ratio of stepping angle divided by body lean angle at step contact (p = .003), which averaged 1.4+/-0.5 for single steppers and 0.6+/-0.5 for multiple steppers, but not with step contact time, stepping angle, or contact forces and joint torques during step contact. CONCLUSIONS: These results suggest that elderly subjects' ability to recover balance with a single backward step depends primarily on the configuration of the body (in particular, the ratio of stepping angle to body lean angle) at step contact.

Aged↗
PubMed2004

Interaction of step length and step rate during sprint running.

UNLABELLED: A "negative interaction" between step length and step rate refers to an increase in one factor resulting in a decrease in the other. PURPOSES: There were three main purposes: a) to investigate the relative influence of the determinants of step length and step rate, b) to determine the sources of negative interaction between step length and step rate, and c) to investigate the effects of manipulation of this interaction. METHODS: Thirty-six athletes performed maximal-effort sprints. Video and ground reaction force data were collected at the 16-m mark. Sprint velocity, step length, step rate, and their underlying determinants were calculated. Analyses included correlations, multiple linear regressions, paired t-tests, and a simple simulation based on alterations in flight determining parameters. RESULTS: A wide range of step length and step rate combinations was evident, even for subgroups of athletes with similar sprint velocities. This was partly due to a negative interaction that existed between step length and step rate; that is, those athletes who used a longer step length tended to have a lower step rate and vice versa. Vertical velocity of takeoff was the most prominent source of the negative interaction. CONCLUSIONS: Leg length, height of takeoff, and vertical velocity of takeoff are all possible sources of a negative interaction between step length and step rate. The very high step lengths and step rates achieved by elite sprinters may be possible only by a technique that involves a high horizontal and low vertical velocity of takeoff. However, a greater vertical velocity of takeoff might be of advantage when an athlete is fatigued and struggling to maintain a high step rate.

Adult↗
PubMed2001

Intrinsic bending and deformability at the T-A step of CCTTTAAAGG: a comparative analysis of T-A and A-T steps within A-tracts.

Introduction of a T-A or pyrimidine-purine step into a straight and rigid A-tract can cause a positive roll deformation that kinks the DNA helix at that step. In CCTTTAAAGG, the central T-A step has an 8.6 degrees bend toward the major groove. We report the structural analysis of CCTTTAAAGG and a comparison with 25 other representative crystal structures from the NDB containing at least four consecutive A or T bases. On average, more local bending occurs at the disruptive T-A step (8.21 degrees ) than at an A-T step (5.71 degrees ). In addition, A-tracts containing an A-T step are more bent than are pure A-tracts, and hence A-A and A-T steps are not equivalent. All T-A steps examined exhibit positive roll, bending towards the major groove, while A-T steps display negative roll and bend slightly towards the minor groove. This illustrates how inherent negative and positive roll are, respectively, at A-T and T-A steps within A-tracts. T-A steps are more deformable, showing larger and more variable deformations of minor groove width, rise, cup, twist, and buckle. Standard deviations of twist, rise, and cup for T-A steps are 6.66 degrees, 0.55 A, and 15.90 degrees, versus 2.28 degrees, 0.21 A, and 2.99 degrees for A-T steps. Packing constraints determine which local values of these helical parameters an individual T-A step will adopt. For instance, with CCTTTAAAGG and three isomorphous structures, CGATTAATCG, CGATATATCG, and CGATCGATCG, crystal packing forces lead to a series of correlated changes: widened minor groove, large slide, low twist, and large rise. The difference in helical parameters between A-T steps lying within A-tracts, versus A-T steps within alternating AT sequences, demonstrates the importance of neighboring steps on the conformation of a given dinucleotide step.

AT Rich Sequence↗
PubMed2003

Step training improves the speed of voluntary step initiation in aging.

BACKGROUND: Falls related to balance dysfunction are among the major problems of older individuals. The timing characteristics of protective voluntary stepping are critically related to effective balance recovery and are often delayed and slowed with age. This study investigated the influence of step training on the timing characteristics of voluntary step initiation in younger and older adults. METHODS: Voluntary reaction time stepping was evaluated before and after training in 12 younger adults and 8 healthy community-dwelling older adults who performed a 3-week regimen of either twice weekly induced step training (destabilizing large waist pulls) or voluntary step practice to a somatosensory reaction stimulus cue (nondestabilizing small waist pulls). RESULTS: Overall, the first step initiation times were slower for the older than for the younger subjects for both the somatosensory reaction stimulus cue task and an auditory transfer cue task. Step completion time was completed earlier for the young posttraining subjects, and older subjects generally had a longer step length. Training resulted in significant reductions in step initiation timing for the old (17%) and young (15%) subjects. Across age groups, the induced training group showed greater reductions in step initiation time than the voluntary practice group for the auditory transfer cue task. CONCLUSIONS: A 3-week period of either voluntary or waist-pull-induced step training reduced step initiation time in older and younger adults. Moreover, compared with voluntary step practice, induced step training resulted in a significantly greater improvement in reaction time stepping for an auditory transfer cue task. At least in the short term, such step training has the potential to help older adults perform more like younger adults in their step initiation timing.

Accidental Falls↗
PubMed2003

A comparative randomized multicentric study comparing the step-up versus step-down protocol in polycystic ovary syndrome.

BACKGROUND: The aim of the study was to evaluate follicular development and ovulation comparing the low-dose step-up and the step-down protocols, in women with clomiphene citrate (CC)-resistant polycystic ovaries. METHODS: Eighty-three women were randomized, and treated with recombinant (r) FSH (Puregon) using either the step-up (n=44) or step-down (n=39) protocol. They were followed up for three cycles unless pregnancy occurred. RESULTS: Monofollicular development occurred in 68.2% of the 85 cycles in the step-up group, as compared with 32% of the 72 cycles in the step-down group (P<0.0001). Hyperstimulation was statistically less frequent using the step-up procedure (4.7 versus 36%, P<0.0001). Both protocols used the same number of FSH units per cycle (951+/-586 versus 967+/-458 in step-up and step-down respectively, P=not significant). However, the duration of ovarian stimulation was statistically different (15.2+/-7.0 days in step-up versus 9.7+/-3.1 in step-down, P<0.001). Ovulation was observed in 70.3% of the cycles using the step-up procedure as compared with 51.3% using the step-down procedure (P<0.01). The cumulative rate of clinical gestations during the study did not differ between the two groups (38.6% in the step-up versus 30.8% in the step-down procedure). CONCLUSIONS: The step-up protocol using rFSH (Puregon), is more efficient in obtaining a monofollicular development and ovulation than the step-down protocol, in women with CC-resistant polycystic ovaries. Although the duration of stimulation is longer, the rate of ovarian hyperstimulation is much lower using the step-up protocol.

Adult↗
PubMed1990

[The use of a test phantom in step-shaped forms (test steps) for the clarification of different problem situations in x-ray diagnosis. 1. The use of test steps for the estimation of image quality after modified darkroom technics].

Properly exposed radiographs and under- or overexposed ones were processed differently with regard to temperature and time. Using a step wedge for the objective estimation, the alteration of well-exposed radiographs by neglecting time and temperature control was examined. Further information is given about the possibility to improve the quality of wrongly exposed radiographs by manipulation of the processing, and about the quantity of acceptable radiographs received in this way. Stop bath, fixation bath, wash bath and drying were performed regularly. The result showed, that the only chance to get high quality radiographs is by exact and correct working.

Animals↗
PubMed2002

Effects of age, step direction, and reaction condition on the ability to step quickly.

BACKGROUND: The ability to take a step quickly is important for balance maintenance during activities of daily living. The purpose of this study was to investigate the effects of age, reaction condition, and step direction on the ability to take a volitional step as fast as possible. METHODS: The performance of a voluntary step task was measured in young adult (mean age 20, SD 0.9 years), young-old adult (mean age 67, SD 3.7 years), and old adult (mean age 78, SD 2.3 years) healthy female participants. Each participant stepped as fast as possible in eight directions in response to a visual cue in a simple or choice reaction time condition. The effects of age, reaction condition, and step direction and their interactions on the primary outcome variables of response time, step liftoff, and step landing time were examined. RESULTS: The normal aging process progressively increased the response, liftoff, and landing times. The choice reaction time condition, compared to the simple, had significantly increased response, liftoff, and landing times. Step direction significantly affected the liftoff and landing times, with lateral, diagonal, and anterior and posterioir (A-P) times increasing, respectively. CONCLUSIONS: We found substantial declines in the ability to step rapidly in healthy adults as age increased. When a decision was required regarding the step direction, the step performance also declined. Step direction also significantly affected step performance. The assessment of voluntary step performance, which may be an indicator of balance ability, should include dimensions of both direction and the choice condition.

Adult↗
PubMed1982

Interlimb coordination during stepping in the cat: in-phase stepping and gait transitions.

The coordination of step cycles between all 4 limbs during in-phase stepping and during transitions to and from alternate stepping was studied in 12 adult cats during repeated overground stepping trials. The temporal spacing of step cycles of the different limbs was determined from analysis of electromyographic (EMG) activity in a single extensor muscle of each limb. Patterns of coordination of the different limbs were established on the basis of the frequency with which phase values separating step cycles were encountered. Steps in which the phasing of step cycles of the two hindlimbs were closer to true in-phase coordination than true alternation (phase between 270 degrees and 90 degrees) and where similar coupling was found in both the preceding and following steps were defined as steady state conditions. Distinct patterns of coordination of forelimb-forelimb and forelimb-hindlimb step cycles were noted under steady state conditions. During stepping sequences which include transitions either to or from alternate stepping, both gradual and abrupt phase changes were found. The changes in both forelimb-forelimb and forelimb-hindlimb phase relationships were more often gradual than abrupt. Where abrupt changes were encountered in the change in phase relationships between one such limb pair the phase change in the other pair was gradual. Changes in hindlimb-hindlimb phase relationships during transitions were nearly always abrupt. It is concluded that the 4 limbs are coordinated during in-phase stepping according to a few patterns, but that the variability about these patterns makes their association with simple neural circuitry rather speculative. The finding that transitions were most often gradual is interpreted in terms of a state-dependent model of interlimb control, in which the type of transition utilized depends on the strength of neural coupling of step cycles of all 4 limbs at the time that the transition is initiated.

Animals↗
PubMed2004

Comparison of procedural errors resulting during root canal preparations completed by senior dental students in patients using an '8-step method' versus 'serial step-back technique'.

OBJECTIVE: To compare procedural errors that occur in patients during root canal preparation by senior dental students using a new '8-step method' versus the traditional 'serial step-back technique.' STUDY DESIGN: Senior dental students treated 221 root canals of maxillary and mandibular teeth. Instrumentation included coronal flaring with Gates-Glidden reamers and standardized stainless steel K-files in all teeth. A new 8-step method was used to prepare 67 canals using standardized stainless steel hand instruments (8-step SS) and 69 canals using the rotary Nickel Titanium instruments (8-step NiTi). The traditional serial step-back technique (step-back) was used for 85 root canals. In the apical third, reaming or filing motions were used up to sizes 25 and only reaming motion in sizes larger than 25 with the new 8-step method. A filing motion was used in the step-back for all sizes. Root canals of all groups were obturated with gutta-percha points and AH26 using a lateral condensation technique. Pre- and postoperative radiographs were taken of each tooth. Procedural errors were recorded and statistically analyzed using a binomic test for comparison of proportion. RESULTS: Procedural errors detected consisted of 2 canals with transportation (3%) with the 8-step SS, and 3 canals (4%) with transportation with 8-step NiTi. There were no canal obstructions or instrument separations. With the step-back, 20 canals were transported (24%), 7 canals had obstructions (8%), and in 1 canal instrument was separated (1%). CONCLUSIONS: The new 8-step method resulted in fewer procedural errors than the traditional serial step-back technique when senior students prepared root canals in patients either by hand with standardized K-files or by rotary NiTi instrumentation.

Bismuth↗
PubMed2003

Can primary care doctors prescribe exercise to improve fitness? The Step Test Exercise Prescription (STEP) project.

BACKGROUND: Sedentary lifestyle is associated with adverse health outcomes. Available evidence suggests that, despite positive attitudes toward regular exercise in promoting a healthy lifestyle, few physicians actually prescribe exercise for their patients. Barriers include lack of skills and standard office instruments. Because primary care physicians have regular contact with a large proportion of the population, the impact of preventive health interventions may be great. OBJECTIVES: To determine the effect of an exercise prescription instrument (i.e., Step Test Exercise Prescription [STEP]), compared to usual-care exercise counseling delivered by primary care doctors on fitness and exercise self-efficacy among elderly community-dwelling patients. DESIGN: Randomized controlled trial; baseline assessment and intervention delivery with postintervention follow-up at 3, 6, and 12 months. SETTING: Four large (>5000 active patient files) academic, primary care practices: three in urban settings and one in a rural setting, each with four primary care physicians; two clinics provided the STEP intervention and two provided usual care control. PARTICIPANTS: A total of 284 healthy community-dwelling patients (72 per clinic) aged >65 years were recruited in 1998-1999. INTERVENTION: STEP included exercise counseling and prescription of an exercise training heart rate. MAIN OUTCOME MEASURES: The primary outcome measure was aerobic fitness (VO(2max)). Secondary outcomes included predicted VO(2max) from the STEP test, exercise self-efficacy (ESE), and clinical anthropometric parameters. RESULTS: A total of 241 subjects (131 intervention, 110 control) completed the trial. VO(2max) was significantly increased in the STEP intervention group (11%; 21.3 to 24ml/kg/min) compared to the control group (4%; 22 to 23ml/kg/min) over 6 months (p <0.001), and 14% (21.3 to 24.9ml/kg/min) and 3% (22.1 to 22.8ml/kg/min), respectively, at 12 months (p <0.001). A similar significant increase in ESE (32%; 4.6 vs 6.8) was observed for the STEP group compared to the control group (22%; 4.2 vs 5.4) at 12 months (p < 0.001). Systolic blood pressure decreased 7.3% and body mass index decreased 7.4% in the STEP group, with no significant change in the control group (p <0.05). Exercise counseling time was significantly (p <0.02) longer in the STEP (11.7+/-3.0 min) compared to the control group (7.1+/-7.0 min), but more (p <0.05) subjects completed > or =80% of available exercise opportunities in the STEP group. CONCLUSIONS: Primary care physicians can improve fitness and exercise confidence of their elderly patients using a tailored exercise prescription (e.g., STEP). Further, STEP appears to maintain benefits to 12 months and may improve exercise adherence. Future study should determine the impact of combining cognitive/behavior change strategies with STEP.

Aged↗
PubMed2004

Online mutability of step direction during rapid stepping reactions evoked by postural perturbation.

Stepping reactions are often triggered rapidly in response to loss of balance. It has been unclear whether spatial step parameters are defined at time of step-initiation or whether they can be modulated online, during step execution, in response to sensory feedback about the evolving state of instability. This study explored the capacity to actively alter step direction subsequent to step initiation in six healthy young-adult subjects. To elicit forward-step reactions, subjects were released suddenly from a tethered forward lean. A second perturbation (medio-lateral support-surface translation) was applied at lags of 0-200 ms. Active reaction to the second perturbation was determined primarily through analysis of swing-leg hip-abductor activation. In addition, to gauge the biomechanical consequence of the changes in muscle activation, we compared the measured medio-lateral swing-foot displacement to that predicted by a simple passive mechanical model. Perturbations at 0-100 ms lag evoked active medio-lateral swing-foot deviation, allowing balance to be recovered with a single step. However, when the second perturbation occurred near foot-off (200-ms lag), there was no evidence of active alteration of step direction and subjects typically required additional steps to recover balance. The results suggest that step direction can be reparameterized during early stages of stepping reactions, but that step direction was not actively modulated in response to perturbation arising near start of swing phase.

Acceleration↗