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PubMed1994

Beta-adrenergic receptor antagonist antihypertensive medications impair arousal-induced modulation of working memory in elderly humans.

It is well-established that administration of moderate doses of the adrenal catecholamines epinephrine or norepinephrine shortly after training results in the enhancement of later retention performance in laboratory animals. These substances, released endogenously as a result of arousal, are thought to modulate memory processes by stimulating peripheral receptors that send neural messages to the brain, thus altering the memory storage process. The applicability of this hypothesis to the modulation of memory processes in humans was tested in this experiment by using elderly subjects who were chronically taking beta-receptor antagonist medications to control hypertension. A moderate level of muscle-tension-induced arousal was produced by having subjects squeeze a hand dynamometer during the initial storage and recall of highlighted words in short 200-word paragraphs. Twenty young normal individuals, 22 normotensive elderly subjects, 21 elderly subjects taking either calcium-channel blockers or angiotensin-converting enzyme inhibitors to control hypertension, and 21 elderly subjects taking beta-blocker antihypertensive medications served as subjects. The young subjects, normal elderly subjects, and those taking non-beta-blocker medications all showed enhanced long-term recognition performance as a result of the arousal manipulation. However, those subjects chronically taking beta-receptor-antagonist medications showed no enhancement of memory.

Adrenergic beta-Antagonists↗
PubMed2006

Isokinetic dynamometry in elderly women undergoing total knee arthroplasty: a comparative study.

OBJECTIVE: The present study assessed the reliability and validity of isokinetic dynamometry in the qualitative determination of the evolution of total knee arthroplasty. CASES: 20 patients whose mean age was 71.35 years, undergoing knee arthroplasty, and 25 controls whose mean age was 71.36 years. METHOD: Computerized isokinetic assessment of flexor and extensor muscles using a CYBEX 6000 dynamometer. RESULTS: The total flexor/extensor effort ratio for the treated side of patients vs the nondominant side of controls was not significantly different. The flexion/extension ratio concerning maximum torque for the treated side of patients vs the nondominant side of controls was significantly different. CONCLUSION: By detecting deficiencies in the balance of flexor and extensor muscles (a balance that is required for uniform gait), it will be possible to select specific rehabilitation exercises according to the individual needs of each patient undergoing surgery.

Aged↗
PubMed2004

Reliability of hand-held dynamometry in assessment of knee extensor strength after hip fracture.

OBJECTIVES: To examine the reliability of hand-held dynamometry in assessing knee extensor strength in inpatients undergoing rehabilitation after hip fracture and to examine the discriminant validity of this measure. DESIGN: A total of 16 subjects (14 women; mean +/- SD, 79 +/- 7 yrs) undergoing inpatient rehabilitation after hip fracture volunteered to participate. Isometric knee extensor strength of the fractured and unfractured sides was determined with a hand-held dynamometer. Subjects were retested 1-2 days after the initial testing session. RESULTS: Test-retest intraclass correlation coefficients were high for both the fractured (0.91) and unfractured legs (0.90). A low coefficient of variation was observed for both the fractured (15.3%) and unfractured (14.7%) sides. The maximal knee extensor strength was significantly different when comparing the fractured (7.9 +/- 3 kg) and unfractured (15.6 +/- 4 kg) legs. When comparing test 1 and test 2 mean values for the fractured leg, the scores significantly differed (t = 3.14, P < 0.01), with 13 of 16 subjects scoring higher on test 2. CONCLUSIONS: Hand-held dynamometry is a reliable and valid tool for assessment of knee extensor strength after hip fracture. Reduced knee extensor strength in the fractured leg may be an important component limiting rehabilitation progress in these patients.

Aged↗
PubMed2004

The effect of force distribution and magnitude at the hand-tool interface on the accuracy of grip force estimates.

The ability to accurately estimate grip force requirements may be important in exposure assessment, determining fitness for duty, or setting rehabilitation goals. This study investigates the effects of learning and experience, measurement system, and the nature of the task on grip force estimate accuracy. The grip forces applied during "pure" power grip tasks and simulated meat cutting tasks conducted in the laboratory, and during meat cutting operations at meat packing plants were measured with an instrumented tool handle. Estimates were recorded using the tool handle and a modified hand dynamometer. The results indicate that estimate accuracy varied greatly from individual to individual. No significant effect of learning on estimate accuracy was observed. The result of the meat cutting simulation and field study suggest that the force distribution at the hand-tool interface can markedly affect estimates. Great care must be taken in the collection of grip force estimates, as well as in the interpretation of the data. Improved understanding of the factors affecting estimates of grip force requirements should aid in the interpretation of functional capacity evaluations, and in the establishment of goals for rehabilitation.

Adult↗
PubMed1988

Isometric and isokinetic hip abductor strength in persons with above-knee amputations.

Recently introduced prosthetic socket designs for the above-knee amputee (AKA) feature a narrow medial-lateral dimension and emphasize maintenance of the residual limb in full physiologic adduction. Quantitative data on the effect of frontal plane limb position on the isometric hip abductor strength of ten otherwise healthy AKAs were obtained in the standing position. Residual limb isometric and isokinetic abductor strength was also measured and compared with that of the intact limb and with that of ten healthy age-, sex-, and height-matched control subjects using an identical technique. The testing hardware consisted of a modified Cybex II Isokinetic Dynamometer with a custom-made pelvis and trunk stabilizing device. Anthropometric measurements were taken. Results showed an essentially linear increase in residual limb abduction strength with progressive adduction from 30 degrees abduction to 16 degrees adduction. The average increase in abduction torque was .97% (range .29 to 1.5) of the peak neutral position strength per degree of change in femur angle when corrected for the effect of gravity. Similar strength increases with adduction of the femur were found for intact and control limbs. Mean residual limb isometric abduction torque measured 30% less than the intact limb value (p = .0018). The difference between the intact and the control limb mean isometric abduction torques was less than 1%. Isokinetic testing was technically more difficult than isometric testing but revealed similar weakness of the residual limb abductors when compared to the intact and control limbs.

Adult↗
PubMed1986

Physiological profiles of the Canadian Olympic Soccer Team.

Physiological profiles of elite athletes are becoming increasingly important both for the sport scientist and coach, primarily to effectively develop training programs and to use as a motivational tool in the pursuit of excellence. Descriptive profiles were developed on 16 aspirants of the Canadian Olympic Soccer team during their training program at U.B.C. Selected strength measures were obtained from a Cybex II isokinetic dynamometer at 30 degrees sec-1. Metabolic variables were derived utilizing a Beckman metabolic cart interfaced with a Hewlitt Packard 3052A data acquisition system. Protocols involved were the following: VO2max (initial velocity 8.05 km X h-1, greater than 0.805 km X min-1); Anaerobic speed test (AST) (20% grade, 12.8 km X h-1). the nonlinear increase in excess CO2 was utilized to determine the anaerobic threshold (AT). (Table: see text). Recommendations emphasized maintenance of low body fat, increasing maximal aerobic power by approximately 10% and creating a hams/quads ratio of 60%. Also, a nutritional survey and periodic evaluation of iron status is necessary for the athletes.

Adult↗
PubMed2000

Reliability of isokinetic strength measurements of the knee in children with cerebral palsy.

This study evaluates the reliability of isokinetic testing of the knee flexors and extensors in children with cerebral palsy (CP). Twelve children (seven girls, five boys), aged 9 to 15 years, participated in this study. The children's strength was measured bilaterally, using a dynamometer. Each participant was tested twice at an interval of 1 week. During each session, the participant performed five consecutive cycles of knee extension and flexion. Testing velocity was set at 90 degrees/s, and the range of motion was 80 degrees, starting with the knee flexed at 80 degrees and ending in full extension. The measured variable was the peak torque. Reliabilities were determined using intraclass coefficient (ICC) with two-way ANOVA model. The ICCs for individual sessions range from 0.90 to 0.99. ICCs for the eight repetitions over the two sessions range from 0.95 to 0.98. The findings indicate that measuring isokinetic strength in the tested population is highly reliable and should be considered in rehabilitation protocols.

Adolescent↗
PubMed2005

"Psyching-up" enhances force production during the bench press exercise.

We investigated the effect of "psyching-up" on force production during the bench press. Twelve men (mean age +/- SD: 27.4 +/- 11.2 years) and 8 women (20.9 +/- 2.5 years) with strength-training experience performed 5 bench press repetitions on a modified Biodex isokinetic dynamometer during 3 interventions. The interventions were counterbalanced and included a free-choice psych-up, a cognitive distraction, and an attention-placebo. Peak force recorded after psyching-up (mean +/- SD: 764 +/- 269 N.m) was significantly different from both distraction (703 +/- 282 N.m, p = 0.003) and attention-placebo (708 +/- 248 N.m, p = 0.01). The mean percentage increase in peak force from distraction to psyching-up was 11.8% (6 to 18%, 95% confidence interval [CI]) and 8.1% from placebo to psyching-up (3 to 13%, 95% CI). The results of the present study indicate that psyching-up may increase force production during the bench press exercise in participants with at least 1 year strength-training experience.

Adult↗
PubMed2006

Isokinetic profile of wrist and forearm strength in elite female junior tennis players.

BACKGROUND: In tennis, injuries to the elbow and wrist occur secondary to the repetitive nature of play and are seen at increasingly young ages. Isokinetic testing can be used to determine muscular strength levels, but dominant/non-dominant and agonist/antagonist relations are needed for meaningful interpretation of the results. OBJECTIVES: To determine whether there are laterality differences in wrist extension/flexion (E/F) and forearm supination/pronation (S/P) strength in elite female tennis players. METHODS: 32 elite female tennis players (age 12 to 16 years) with no history of upper extremity injury underwent bilateral isokinetic testing using a Cybex 6000 dynamometer. Peak torque and single repetition work values for wrist E/F and forearm S/P were measured at speeds of 90 degrees/s and 210 degrees/s, with random determination of the starting extremity. Repeated measures analysis of variance was used to determine differences between extremities for peak torque and single repetition work values. RESULTS: Significantly greater (p<0.01) dominant arm wrist E/F and forearm pronation strength was measured at both testing speeds. Significantly less (p<0.01) dominant side forearm supination strength was measured at both testing speeds. CONCLUSIONS: Greater dominant arm wrist E/F and forearm pronation strength is common and normal in young elite level female tennis players. These strength relations indicate sport specific muscular adaptations in the dominant tennis playing extremity. The results of this study can guide clinicians who work with young athletes from this population. Restoring greater dominant side wrist and forearm strength is indicated after an injury to the dominant upper extremity in such players.

Adolescent↗
PubMed1993

The effects of dental condition on hand strength and maximum bite force.

Piezoelectric force transducer and hand dynamometer were used for measuring the maximum bite force and hand grasp force on 2034 primary, middle, and high school students. Dental condition and body weight and height were also observed to relate to the force measurements. It was discovered that both forces increased relative to the increase of age, body weight, and body height. Boys had stronger bite force than girls at all age groups, while the grasp force of boys became significantly stronger only after the age of 13. Students who had dentition with decay and missing teeth tended to have weaker bite force, while hand force was not influenced. Bite force does not seem parallel to hand strength and is, instead, related to dental condition.

Adolescent↗
PubMed1996

Quadriceps muscle performance in sitting and standing in young women with patellofemoral pain syndrome and young healthy women.

The aim of this study was to evaluate and compare muscular activation in sitting and standing in patients with patellofemoral pain syndrome and healthy controls. Eleven women with patellofemoral pain syndrome and nine healthy controls were evaluated regarding: (a) muscle performance in sitting compared to standing-knee extensor torque was registered in sitting with a Kin Com dynamometer and in standing with a force plate, and quadriceps muscle activity was registered with EMG in both sitting and standing; and (b) ability to maximally voluntarily activate during sitting isometric knee extension. Maximally tolerated single-twitch electrical stimulation was superimposed on 20, 40, 60, 80 and 100% of maximal voluntary activation. Additional torque from the single twitch was documented. Five patients and all nine controls were tested twice (tests a and b) with 2 days between tests, and high reproducibility could be demonstrated. A significantly higher torque during sitting compared with standing was found in both patients and controls, but with a significant correlation between sitting and standing torque values. No significant difference was found between patients and controls. Single-twitch electrical stimulation superimposed on maximal voluntary activation resulted in increased torque in two of the nine controls compared to 10 of the 11 patients. The average increased torque in the patients were significantly higher than in the controls and estimated to 18%. It was concluded that sitting isometric measurements are representative of the ability to produce standing isometric knee torque. A moderate degree of inhibition was demonstrated during sitting strength measurements in the patients (not studied in standing).

Adolescent↗
PubMed2006

Reliability of knee and ankle strength measures in an older adult population.

Strength training for older adults is increasingly common, yet surprisingly little research has evaluated the reliability of strength testing protocols in this population. Thirty-three volunteers (17 women, 16 men; 72 +/- 6 years) were tested for strength of the knee and ankle using a Biodex 3 dynamometer on 3 separate occasions. The peak torque and work for each test was analyzed for reliability over the last 2 visits using limits of agreement (LOA). The magnitude of the systematic bias was 8 Nm or less for the peak torque and 5 J or less for the work measures. The random error ranged from 9 to 20 Nm and 6 to 24 J for peak torque and work, respectively. Heteroscedasticity was present in 8 of the 20 measures. The ratio LOA ranged from 21% to 43% for these peak torque and work measures. The total error of each strength measure, which was mostly comprised of random error, can be applied to interpretation and development of training protocols for the older adult.

Aged↗
PubMedDate not supplied

Hand grip dynamometry as a predictor of postoperative complications reappraisal using age standardized grip strengths.

A mechanical hand grip dynamometer was used to derive age- and sex-related standard grip strengths from 247 healthy volunteers between 16 and 95 yr old. Preoperative grip strength was measured in 90 patients and related to postoperative complication rates. A grip strength of 85% standard for age and sex was found to be the most effective cut-off for prediction of postoperative complications in terms of sensitivity and specificity, predicting 74% of the complications (p less than 0.05). Specificity is improved over previously published standards related to sex alone especially when assessing the elderly patient (50% vs 21%). A grip strength below the recommended cut-off for age and sex suggests that the patient is in a high-risk group and demands further investigation of nutritional status. Studies of pre-operative nutritional support for the at risk group need to be undertaken.

Adolescent↗
PubMed1995

Deterioration of motor function in myotonic dystrophy and hereditary motor and sensory neuropathy.

In order to obtain more information about the deterioration of motor function in patients with myotonic dystrophy and in patients with hereditary motor and sensory neuropathy, changes in strength and functionality were determined at one year intervals, over a follow-up period of 1 to 5 years. Twenty-five myotonic dystrophy patients and 16 hereditary motor and sensory neuropathy patients participated. Strength measurements were restricted to knee extension and flexion torques measured isokinetically on a dynamometer at two velocities (120 and 60 degrees/s). Functionality was measured as scaled time scores for rising from sitting, rising from supine, walking and stair climbing. Myotonic dystrophy patients showed a reduction of knee extension torques at 60 degrees/sec (mean decrease per year 5.7 Nm, or 9%) as well as a decrease in functionality. Hereditary motor and sensory neuropathy patients showed no statistically significant changes in torques or functionality. The correlation between isokinetically measured knee extension torques and functional scores was statistically significant in myotonic dystrophy but not in hereditary motor and sensory neuropathy. No correlation was found between changes in torques and changes in functional scores.

Adolescent↗
PubMedDate not supplied

Grip and pinch strength in relation to function in denervated hands.

A study was conducted in the Schieffelin Leprosy Research and Training Centre, Karigiri, Tamil Nadu, from March to September 2000 to find out the relationship between grip and pinch strengths and basic activities of daily living (BADL) in leprosy patients. Sixty-two patients (mean age: 36.1 years) suffering from impairment of motor nerve function in one or both hands were included in the study. Grip strength and pinch strength, namely pulp-to-pulp pinch strength, lateral pinch strength, tripod pinch strength, were measured using a hydraulic hand dynamometer and a pinch gauge. BADL was assessed using Karigiri activities of daily living rating scale. Frequency table, mean, median, range, standard deviation, correlation and multiple regressions were used in analysis. The results showed that there was a highly significant correlation (p < 0.001) between the grip and pinch strength and BADL. Multiple regression analysis showed only tripod pinch strength had a significant, independent influence on the BADL. Other two pinch strengths and grip strength were not significant. These results suggest that there is a significant relationship between the grip and pinch strengths and BADL. The tripod pinch strength is the most important hand strength contributing to the problems in BADL. In a measure of association between impairment and disability, the results revealed that out of 62 patients with physical impairment of the hand, 59 (95.2%) had experienced disabilities. This indicated that, despite impairment, 4.8% do not have any disabilities.

Activities of Daily Living↗
PubMed2000

Etiologic factors associated with anterior knee pain in distance runners.

PURPOSE: The objectives of this study were 1) to examine the differences between a noninjured (C) cohort of runners (N = 70) and runners afflicted with anterior knee pain (AKP) according to selected training, anthropometric, rearfoot motion, ground reaction force, and muscular strength and endurance variables; 2) to explore multivariate relationships among these measures in the well and injured groups; and 3) to develop specific hypotheses concerning risk factors for injury that will later be tested in a prospective clinical study. METHODS: High speed videography (200 frames x s(-1)), a force platform (500 Hz), and a Cybex II+ isokinetic dynamometer were used to assess rearfoot motion, ground reaction forces, and knee muscular strength and endurance, respectively. A linear discriminant function was performed on each of the five categories of variables and revealed 19 significant (P < or = 0.05) predictors. These variables were then combined and a final discriminant function analysis was performed. RESULTS: Pronation through the first 10% of stance, arch index, shoe mileage, and extension peak torque were the best overall (P < or = 0.05) predictors. The AKP group had smaller mean values on all four significant predictors. CONCLUSION: With the exception of shoe mileage, which is likely a response to rather than a risk factor for AKP, these results should prove useful to clinicians in identifying runners at risk for anterior knee pain.

Adult↗
PubMed1983

Effects of androgenic-anabolic steroids on neuromuscular power and body composition.

The effects of androgenic-anabolic steroids on neuromuscular power and body composition were studied in nine volunteers experienced with progressive-resistance weight training. By use of double-blind procedures, testosterone cypionate, nandrolone decanoate, and sesame oil (placebo) were administered in a repeated-measures design that counterbalanced treatment order. Duration of each treatment condition was 3 wk. Supplemental protein was provided, and dietary records were maintained throughout the study. Subjects were trained with progressive-resistance weight-training exercises. Isokinetic dynamometer testing revealed that peak torque output was not significantly changed between treatments in 7 out of 10 isolated-joint actions. The hydrostatic weighing results revealed insignificant differences in lean body mass and percent body fat. Significant changes in some treatment means of three peak torque output tests were insufficient to identify any consistent treatment alterations. Since protein and caloric intake was sufficient to elicit anabolic effects from the steroid treatments and weight-training program, the lack of significant results could not be attributed to dietary considerations. Subjects reported subjective feelings of increased strength after administration of anabolic agents, which may partially account for their widespread use. In conclusion, anabolic steroids did not substantially change body composition or the objective power measurements used in this study.

Adult↗
PubMed1990

Eccentric and concentric torque-velocity relationships during arm flexion and extension. Influence of strength level.

Forty men were tested with a computerized dynamometer for concentric and eccentric torques during arm flexion and extension at 0.52, 1.57, and 2.09 rad.s-1. Based on the summed concentric and eccentric torque scores, subjects were placed into a high strength (HS) or low strength (LS) group. The eccentric and concentric segments of the torque-velocity curves (TVCs) were generated using peak torque and constant-angle torque (CAT) at 1.57 and 2.36 rad. Angle of peak torque was also recorded. Compared to LS, HS had significantly greater estimated lean body mass (+10.2 kg) and approximately 25% greater average torque output. Reliability of the peak torque scores on 2 days in 20 subjects was r greater than or equal to 0.85. The difference between observed torques and the mathematically computed criterion torque scores averaged 1% for three validation loads that ranged from 11.4 to 90.4 kg. Statistical analysis revealed that torque output in LS plateaued at low concentric velocities and was also flattened with increasing eccentric velocities. Conversely, torque output for HS increased with decreasing concentric velocities and increased with increasing eccentric velocities. The method of plotting the TVCs for peak or CAT did not influence the pattern of TVC. Eccentric flexion peak torque occurred at a significantly shorter muscle length (1.88 rad) than concentric torque (2.12 rad). This difference was also present for extension; it was 1.88 rad for eccentric and 2.03 rad for concentric torque.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗