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Biomedical subjects

S L Wolf

Publications and source records attributed to S L Wolf.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of a multidimensional anabolic steroid prevention intervention. The Adolescents Training and Learning to Avoid Steroids (ATLAS) Program.

OBJECTIVE: To test a team-based, educational intervention designed to reduce adolescent athletes' intent to use anabolic androgenic steroids (AAS). DESIGN: Randomized prospective trial. SETTING: Thirty-one high school football teams in the Portland, Ore, area. PARTICIPANTS: Seven hundred two adolescent football players at experimental schools; 804 players at control schools. INTERVENTION: Seven weekly, 50-minute class sessions were delivered by coaches and student team leaders, addressing AAS effects, sports nutrition and strength-training alternatives to AAS use, drug refusal role play, and anti-AAS media messages. Seven weight-room sessions were taught by research staff. Parents received written information and were invited to a discussion session. MAIN OUTCOME MEASURES: Questionnaires before and after intervention and at 9- or 12-month follow-up, assessing AAS use risk factors, knowledge and attitudes concerning AAS, sports nutrition and exercise knowledge and behaviors, and intentions to use AAS. RESULTS: Compared with controls, experimental subjects at the long-term follow-up had increased understanding of AAS effects, greater belief in personal vulnerability to the adverse consequences of AAS, improved drug refusal skills, less belief in AAS-promoting media messages, increased belief in the team as an information source, improved perception of athletic abilities and strength-training self-efficacy, improved nutrition and exercise behaviors, and reduced intentions to use AAS. Many other beneficial program effects remained significant at the long-term follow-up. CONCLUSIONS: This AAS prevention program enhanced healthy behaviors, reduced factors that encourage AAS use, and lowered intent to use AAS. These changes were sustained over the period of 1 year. Team-based interventions appear to be an effective approach to improve adolescent behaviors and reduce drug use risk factors.

Adolescent↗
PubMed1996

Efficacy of insulin and sulfonylurea combination therapy in type II diabetes. A meta-analysis of the randomized placebo-controlled trials.

BACKGROUND: Numerous studies demonstrate the efficacy of the combination therapy of insulin and sulfonylurea in subjects with type II diabetes mellitus. However, two recent meta-analyses of randomized trials during the last decade provided inconsistent conclusions and failed to resolve the controversy. OBJECTIVE: To assess the efficacy of insulin and sulfonylurea combination therapy in type II diabetes mellitus by performing meta-analysis of only the controlled studies selected according to specific strict criteria. METHODS: A computerized literature survey was conducted using the MEDLINE database from January 1980 through March 1992 with the search headings of "sulfonylurea" and "insulin" and "combination therapy in diabetes mellitus. "A manual search was also performed using references from each retrieved report. Case reports, review articles, editorials, and citations reported in non-English-language journals without English translations were excluded. Forty-three citations were obtained. Four strict inclusion criteria were used to select studies: randomized, placebo-controlled trials (oral agent plus insulin vs placebo plus insulin); homogeneous target population (subjects with type II diabetes); intervention using the same sulfonylurea agent in a combination therapy; and uniform outcome measures to evaluate efficacy such as body weight; values for serum glucose, glycohemoglobin, and C peptide; daily insulin dosage; and lipid concentrations. More stringent qualitative subcriteria were then used to eliminate bias in the final unanimous selection by two blinded reviewers. Data were pooled and analyzed using Student's t test and Winer's combined test. RESULTS: Sixteen studies satisfied the inclusion criteria. Metabolic control improved with the combination therapy as reflected by a significant lowering of fasting serum glucose values (P < .01) and glycohemoglobin concentrations (P < .025). Moreover, improved metabolic control was achieved with a significantly smaller daily insulin dose (P < .01) and without a significant change in body weight. Finally, the combination therapy enhanced the endogenous insulin secretion as expressed by an increase in fasting serum C peptide concentration (P < .05). CONCLUSIONS: Combination therapy with insulin and sulfonylurea may be a more appropriate and a suitable option to insulin monotherapy in subjects with non-insulin-dependent diabetes in whom primary or secondary failure to sulfonylurea developed. It may also be a more cost-effective way of long-term management in this group of subjects, especially in the elderly.

Blood Glucose↗
PubMed1996

The Adolescents Training and Learning to Avoid Steroids (ATLAS) prevention program. Background and results of a model intervention.

OBJECTIVE: To develop and test a school-based intervention to prevent anabolic androgenic steroid use among high-risk adolescent athletes. DESIGN: Nonrandom controlled trial. SETTING: Two urban high schools. PARTICIPANTS: Fifty-six adolescent football players at the experimental school and 24 players at the control school. INTERVENTION: Eight weekly, 1-hour classroom sessions delivered by the coach and adolescent team leaders, and eight weight-room sessions delivered by research staff. The intervention addressed sports nutrition and strength training as alternatives to steroid use, drug refusal role play, and antisteroid media campaigns. OUTCOME MEASURES: A preintervention and postintervention questionnaire that assessed attitudes toward and intent to use steroids and other drugs; knowledge of drug effects; and diet, exercise, and related constructs. RESULTS: Compared with controls, experimental subjects were significantly less interested in trying steroids after the intervention, were less likely to want to use them even if their friends used them, were less likely to believe steroid use was a good idea, believed steroids were more dangerous, had better knowledge of alternatives to steroid use, had improved body image, increased their knowledge of diet supplements, and had less belief in these supplements as beneficial. CONCLUSIONS: Significant beneficial effects were found despite the sample size, suggesting that the effects of the intervention was large. This outcome trial demonstrates an effective anabolic androgenic steroid prevention program for adolescent athletes, and the potential of team-based interventions to enhance adolescents' health.

Adolescent↗
PubMed1996

Determining consistency of elbow joint threshold angle in elbow flexor muscles with spastic hypertonia.

BACKGROUND AND PURPOSE: Threshold angle, the point in passive range of motion where a muscle response or torque change is elicited, may be a potentially valid measure of hypertonus. Because the relationship of initial muscle length to threshold angle has not been addressed previously, this preliminary study examined whether starting elbow joint position and speed of stretch to elbow flexor muscles affect threshold angle. SUBJECTS: Five subjects with stroke-induced hypertonia of the elbow flexor muscles participated. METHODS: Two starting angles and two designated stretch speeds were applied randomly by a torque motor at each of three testing sessions. RESULTS: Starting angle, subject, and session affected threshold angle. A 90-degree starting angle at a stretch speed of approximately 1.0 radian/s produced the most consistent threshold angles between sessions within subjects, and threshold angle was relatively consistent for some subjects, irrespective of speed. CONCLUSION AND DISCUSSION: If future research indicates that these data can be generalized, the use of threshold angle as a consistent measure of hypertonia will require comparison within individuals, use of a consistent starting angle, and a movement condition of a 90-degree starting angle and an approximate movement speed of 1.0 radian/s across sessions.

Adult↗
PubMed1996

Theoretical basis for patterning EMG amplitudes to assess muscle dysfunction.

A theoretical basis for assessing muscle dysfunction due to sprain/strain injuries is presented. We propose that muscle tissue trauma results in an alteration in the patterns of neural recruitment, a reduction in the force-generating capability of the injured muscle, and/or pain sensations. Furthermore, a lower than normal recruitment of motoneuron pools in the injured area can result in elevated recruitment levels from compensating motoneuron pools for a given motor task. It is proposed that these changes in motoneuron recruitment can be readily apparent in the ratios of EMG amplitudes among multiple pairs of muscles associated kinoffologically with the affected muscle. Chronic compensating actions, such as those resulting from faulty neural feedback of the force-length-velocity relationships for a stretched tendon or muscle unit, could cause further injuries. It is proposed that consistent and valid measures of ratios of EMG amplitudes between many muscle pairs acquired for well-defined motor tasks can be used to facilitate diagnoses and direct treatment strategies for sprain/strain injuries and pain.

Back↗
PubMed1996

Reducing frailty and falls in older persons: an investigation of Tai Chi and computerized balance training. Atlanta FICSIT Group. Frailty and Injuries: Cooperative Studies of Intervention Techniques.

OBJECTIVE: To evaluate the effects of two exercise approaches, Tai Chi (TC) and computerized balance training (BT), on specified primary outcomes (biomedical, functional, and psychosocial indicators of frailty) and secondary outcomes (occurrence of falls). DESIGN: The Atlanta FICSIT (Frailty and Injuries: Cooperative Studies of Intervention Techniques), a prospective, randomized, controlled clinical trial with three arms (TC, BT, and education [ED]. Intervention length was 15 weeks, with primary outcomes measured before and after intervention and at 4-month follow-up. Falls were monitored continuously throughout the study. SETTING: Persons aged 70 and older living in the community. PARTICIPANTS: A total of 200 participants, 162 women and 38 men; mean age was 76.2. MEASUREMENTS: Biomedical (strength, flexibility, cardiovascular endurance, body composition), functional (IADL), and psychosocial well-being (CES-D scale, fear of falling questionnaire, self-perception of present and future health, mastery index, perceived quality of sleep, and intrusiveness) variables. RESULTS: Grip strength declined in all groups, and lower extremity range of motion showed limited but statistically significant changes. Lowered blood pressure before and after a 12-minute walk was seen following TC participation. Fear of falling responses and intrusiveness responses were reduced after the TC intervention compared with the ED group (P = .046 and P = .058, respectively). After adjusting for fall risk factors, TC was found to reduce the risk of multiple falls by 47.5%. CONCLUSIONS: A moderate TC intervention can impact favorably on defined biomedical and psychosocial indices of frailty. This intervention can also have favorable effects upon the occurrence of falls. Tai Chi warrants further study as an exercise treatment to improve the health of older people.

Accidental Falls↗
PubMed1996

Long latency ankle responses to dynamic perturbation in older fallers and non-fallers.

OBJECTIVE: The purpose of this study was to examine the effects of falling history and aging on the latency and magnitude of long latency responses in the lateral gastrocnemius (LG) and tibialis anterior (TA) muscles of older adults. DESIGN: Single observation study. SETTING: Emory University School of Medicine, Center for Rehabilitation Medicine, serving the greater Atlanta, Georgia, area. PARTICIPANTS: There were 62 community-dwelling adults aged 60 or older, 32 with a history of two or more unexplained falls in the past year and 30 with no history of falls in the past year. MEASUREMENTS: The electromyographic activity of the gastrocnemius and tibialis anterior muscles was recorded bilaterally during repeated 10 degree dorsiflexion perturbations to standing subjects at the acceleration of gravity and a velocity of approximately 100 deg/sec. The latency and magnitude of the long latency EMG responses (LLR) of both muscles were determined and compared between individuals by falls history and by decades of age. MAIN RESULTS: No significant differences between falls status groups existed for mean LLR latencies or magnitudes of either LG or TA. Attenuation of the LLR throughout the trials was significantly different between groups. Non-fallers demonstrated attenuation of the LG magnitude over the first five stretches. Fallers showed maladaptation of the LG response, with the latency becoming shorter over 25 trials. More than half of the subjects in both groups had one or more instances of temporal reversal of the response latencies, with the TA response occurring earlier than the LG response during the first five stretches. No differences existed in the LLR between age decades within faller or non-faller groups. A timed measure of mobility (Up & Go) showed a significant difference between falls status, but not between age decades in either group. CONCLUSIONS: Lack of differences between falls status and age decade groups over all trials suggests that LLRs remain intact between older fallers and non-fallers and between older age groups. The mechanism of perturbation is a distinguishing feature of this study and probably contributes to our findings. The appearance of an atypical response strategy in both groups, where the TA response often occurs before the LG response, has raised the question of whether there is always a stereotypical pattern of LLRs during postural perturbations outside the experimental setting.

Accidental Falls↗
PubMed1996

Reducing human biceps brachii spinal stretch reflex magnitude.

1. Nine subjects received 6 baseline and 24 training sessions, each consisting of 250 elbow joint stretch perturbations into extension. The training sessions were designed to reduce the subjects' biceps brachii spinal stretch reflexes (SSR). Changes in longer-latency responses and short-latency brachioradialis responses were also monitored. Background electromyogram activity was recorded from the lateral head of triceps brachii during the biceps sampling intervals. These data were compared with those form 12 control subjects who received equal numbers of stretches over an extended baseline (i.e., without application of a training paradigm). 2. Training subjects reduced their mean biceps SSR responses by 24%, whereas control subjects increased their responses by 12% When changes in activity were grouped by sets of six consecutive sessions following the baseline interval, group-by-time interaction was observed. Training subjects showed significant reductions from baseline after the first raining set. The increased magnitude of biceps SSR for control subjects was significantly larger than baseline in sets 2-5. After the first training interval, all subsequent differences between groups were statistically significant. 3. The brachioradialis showed greater response variability, but these responses paralleled those seen in biceps brachii. The training group reduced their brachioradialis responses by 18%, whereas the control group increased their responses by 12%. Background activity recorded over the lateral head of triceps brachii during the biceps brachii SSR window became smaller in both groups. 4. Comparison of data between control subjects and subjects who had undergone biceps SSR up-training in previous studies suggests that the small increase seen among the present control subjects was probably not the result of a direct training effect. 5. Baseline differences in longer-latency response onset time were seen between groups. Over extended baseline sessions, longer-latency responses showed only a 1% onset, representing a change of 0.3 ms, in the control group. A 1.3% later onset, equaling a change of 1.1 ms, was observed over conditioning sessions in the training group. When analyzed by sets following baseline, neither group showed significant within- or between-group changes over time. 6. The magnitude of the longer-latency biceps brachii response showed 7% and 37% reductions for the control and training groups, respectively. No difference in set averages was seen within groups, but a significant difference was measured over sets 2-4 between groups. Reductions in the magnitude of longer-latency responses in training subjects were more obvious in later training sessions. 7. These data suggest that 1) the biceps brachii SSR can be reduced in human subjects; 2) concurrent changes are often observed in the synergist brachioradialis; and 3) the reduced biceps SSR magnitude is not linked to a compensatory increase in antagonist muscle activity. Reductions in the magnitude of longer-latency biceps brachii activity seen in parallel with the decreased SSR may imply that some degree of supraspinal processing is required to achieve this task.

Adolescent↗
PubMed1995

The effects of exercise on falls in elderly patients. A preplanned meta-analysis of the FICSIT Trials. Frailty and Injuries: Cooperative Studies of Intervention Techniques.

OBJECTIVE: To determine if short-term exercise reduces falls and fall-related injuries in the elderly. DESIGN: A preplanned meta-analysis of the seven Frailty and Injuries: Cooperative Studies of Intervention Techniques (FICSIT)--independent, randomized, controlled clinical trials that assessed intervention efficacy in reducing falls and frailty in elderly patients. All included an exercise component for 10 to 36 weeks. Fall and injury follow-up was obtained for up to 2 to 4 years. SETTING: Two nursing home and five community-dwelling (three health maintenance organizations) sites. Six were group and center based; one was conducted at home. PARTICIPANTS: Numbers of participants ranged from 100 to 1323 per study. Subjects were mostly ambulatory and cognitively intact, with minimum ages of 60 to 75 years, although some studies required additional deficits, such as functionally dependent in two or more activities of daily living, balance deficits or lower extremity weakness, or high risk of falling. INTERVENTIONS: Exercise components varied across studies in character, duration, frequency, and intensity. Training was performed in one area or more of endurance, flexibility, balance platform, Tai Chi (dynamic balance), and resistance. Several treatment arms included additional nonexercise components, such as behavioral components, medication changes, education, functional activity, or nutritional supplements. MAIN OUTCOME MEASURES: Time to each fall (fall-related injury) by self-report and/or medical records. RESULTS: Using the Andersen-Gill extension of the Cox model that allows multiple fall outcomes per patient, the adjusted fall incidence ratio for treatment arms including general exercise was 0.90 (95% confidence limits [CL], 0.81, 0.99) and for those including balance was 0.83 (95% CL, 0.70, 0.98). No exercise component was significant for injurious falls, but power was low to detect this outcome. CONCLUSIONS: Treatments including exercise for elderly adults reduce the risk of falls.

Accidental Falls↗
PubMed1995

Contralateral and long latency effects of human biceps brachii stretch reflex conditioning.

Results from previous studies on monkeys and human subjects have demonstrated that the biceps brachii spinal stretch reflex (SSR) can be operantly conditioned. The extent to which conditioning paradigms influence contralateral SSRs or longer latency responses in the same limb has not been examined. Nine subjects were given 10 training sessions to either increase or decrease the size of their biceps brachii SSR. Group changes were compared to the mean of six baseline (control) sessions. Both groups showed progressive SSR changes over the training sessions. Up-trained subjects increased their SSR responses by an average of 135.3% above baseline, with the last three sessions showing a 237.5% increase, while down-trained subjects reduced their average SSR responses by 43.4%, with a 52.7% reduction over the last three sessions. ipsilateral longer latency responses showed average changes of 68.9% and -68.7% for up- and down-trainers, respectively. As in the case of SSRs, these responses changed progressively over sessions, with a 131.5% increase seen in the last three up-training sessions and an 82.4% reduction over the same period for down-trainers. Correlation coefficients between SSR and longer latency responses were high (R = 0.90, up-trainers; R = 0.87, down-trainers). Contralateral SSR and longer latency responses, measured in the absence of feedback and at least 10 min after ipsilateral conditioning, showed directional changes that were similar to the trained side, but their magnitudes were not as profound. Collectively, these data suggest that unilateral SSR conditioning affects spinal circuits controlling contralateral SSRs and influences longer latency responses.

Adult↗
PubMed1995

A cross-sectional validation study of the FICSIT common data base static balance measures. Frailty and Injuries: Cooperative Studies of Intervention Techniques.

BACKGROUND: Two simple balance scales comprising three or four familiar tests of static balance were developed, and their validity and reliability are described. The scales were such that the relative difficulties of the basic tests were taken into consideration. METHODS: Using FICSIT data, Fisher's method was used to construct scales combining ability to maintain balance in parallel, semi-tandem, tandem, and one-legged stances. Reliability was inferred from the stability of the measure over 3-4 months. Construct validity was assessed by cross-sectional correlations. RESULTS: Test-retest reliability (over 3-4 months) was good (r = .66). Validity of the FICSIT-3 scale was suggested by its low correlation with age, its moderate to high correlations with physical function measures, and three balance assessment systems. The FICSIT-4 scale discriminated balance over a wide range of health status; the three-test scale had a substantial ceiling effect in community samples. CONCLUSION: A balance scale was developed that appears to have acceptable reliability, validity, and discriminant ability.

Aged↗
PubMed1994

Operant conditioning of spinal stretch reflexes in patients with spinal cord injuries.

Hyperactive spinal stretch reflexes (SSRs) often occur with spinal cord injuries (SCI). These altered SSRs may impair movement. Recent studies in monkeys and human subjects have indicated that the magnitude of SSRs can be modulated using operant conditioning. The purpose of this study was to determine whether hyperactive biceps brachii SSRs could be operantly conditioned downward. Seventeen chronic (> 1 year postlesion) spinal cord-injured patients participated. Subjects were trained to keep biceps background (prestretch) electromyographic (EMG) activity and elbow angle at predetermined levels prior to having the elbow rapidly extended by a torque motor to elicit the biceps SSR. All subjects participated in six baseline sessions over a 2-week period. Then, subjects were randomly assigned to either control or training groups for the next 24 sessions over an 8-week period. By the end of the study, training subjects had significantly reduced biceps SSRs (t test, P < 0.001), while control subjects SSRs were not significantly reduced (t test, P > 0.05). The reduced SSRs persisted for up to 4 months following cessation of training. The results of this study support the hypothesis that hyperactive SSRs can be operantly conditioned downward in SCI patients.

Adolescent↗
PubMed1994

Comparison of the effects of exercise in water and on land on the rehabilitation of patients with intra-articular anterior cruciate ligament reconstructions.

BACKGROUND AND PURPOSE: Exercises in water have been shown to be effective for improving strength and passive range of motion (PROM). Traditional rehabilitation following intra-articular anterior cruciate ligament (ACL) reconstruction has taken place on land. This study was designed to compare the effects of exercises in water on strength and girth of the thigh musculature, knee PROM, joint laxity, effusion, and functional outcome with the effects of similar exercises on land in subjects following intra-articular reconstruction of the ACL. SUBJECTS: Twenty subjects were randomly assigned to either a group that exercised on land or a group that exercised in water. METHODS: Thigh girth, joint effusion, and knee PROM measurements were recorded at 2-week intervals for the first 8 weeks postoperatively. Isokinetic and isometric peak torque measurements for the thigh musculature, knee joint laxity assessments, and Lysholm scores were obtained at the end of 8 weeks. RESULTS: Higher outcome scores were recorded in the water group than in the land group, as measured by Lysholm scales. No differences were noted between groups for knee PROM, thigh girth, or quadriceps femoris muscle performance. In the water group, less joint effusion was noted after the 8 weeks. In the land group, greater peak torque for isokinetic knee flexion was recorded. CONCLUSION AND DISCUSSION: Although exercise in water may not be as effective as exercise on land for regaining maximum muscle performance, rehabilitation in water may minimize the amount of joint effusion and lead to greater self-reports of functional improvement in subjects with intra-articular ACL reconstructions.

Activities of Daily Living↗
PubMed1994

Overcoming limitations in elbow movement in the presence of antagonist hyperactivity.

BACKGROUND AND PURPOSE: A traditional perspective on rehabilitation of patients with abnormal muscular hyperactivity presumes that relaxation should be facilitated prior to recruitment of antagonists, if effective movement about a joint is to occur. The purpose of the study was to determine the effect of training weak triceps brachii muscles, with hyperactivity present in the opposing biceps brachii muscles, on elbow function in individuals at least 1 year poststroke. SUBJECTS: Sixteen patients with chronic stroke were randomly assigned to receive electromyographic biofeedback to retrain the triceps muscle (n = 8) or to receive conventional movement training (n = 8). METHODS: Both groups participated in 5 baseline and 10 training sessions involving tasks requiring elbow extension. Preintervention and postintervention measurements included elbow extension range of motion, triceps and biceps muscle electromyographic activity during performance of elbow extension, resisted elbow extension, and a reaching task. RESULTS: Two-sample t-test results of between-group comparisons for each variable were not significant. One-sample t-test results of within-group comparisons showed significant increases in triceps muscle mean electromyographic activity during two of the three tasks for the feedback group, but not for the nonfeedback group. Passive and active range of motion in both groups increased significantly, although biceps muscle co-contraction persisted. CONCLUSION AND DISCUSSION: These results suggest that functional improvements at the elbow may have been due to biomechanical (peripheral) rather than neuromuscular (central) changes about the joint. Furthermore, these preliminary data indicate that patients with stroke may be trained to increase movement without first being trained to specifically inhibit hyperactivity in muscles.

Aged↗
PubMed1994

Towards new measures of information retrieval evaluation.

All of the methods currently used to assess information retrieval (IR) systems have limitations in their ability to measure how well users are able to acquire information. We utilized a new approach to assessing information obtained, based on a short-answer test given to senior medical students. Students took the ten-question test and then searched one of two IR systems on the five questions for which they were least certain of their answer Our results showed that pre-searching scores on the test were low but that searching yielded a high proportion of answers with both systems. These methods are able to measure information obtained, and will be used in subsequent studies to assess differences among IR systems.

Evaluation Studies as Topic↗