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Craig A. Horswill

As a result of exercise-induced sweating, athletes and trained individuals can lose up to 3 L of fluid per hour. Fluid replacement is required to maintain hydration and allow the athlete to continue to perform. Inadequate fluid intake will adversely affect temperature regulation, cardiovascular function, and muscle metabolism. To maximize fluid intake and effectively replace fluid, athletes must employ behavioral strategies. Athletes can also select beverages with characteristics that complement their behavioral efforts. Palatability, rapid absorption, retention of the fluid, and ergogenicity are the major attributes to consider for enhancing hydration during training and physical activity.

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Susanne Fuchs, Guido Schuette, Hartmut Witte, and Carsten Oliver Tibesku

A new design of total knee prosthesis without anterior patellar flange was developed to preserve the anatomical shape of the patellofemoral joint. The aim of the current study was to experimentally compare patellofemoral contact area and pressure in a nonreplaced knee, in a knee after implantation of a conventionally designed total knee arthroplasty, and in a knee after implantation of the newly designed total knee arthroplasty without patellar flange. Six cadaveric legs were examined before and after implantation of either a conventional or a newly developed total knee arthroplasty, both without patellar replacement. The essential change in design is the absence of an anterior patellar flange. Contact area and pressure were measured using pressure sensitive films in 45°, 60°, 90°, and 120° of flexion and the results were compared between the different prosthesis designs and with the nonreplaced knee. The prosthesis without patellar flange showed less average and maximum pressure than the conventional prosthesis. Compared with the nonreplaced knee, the conventional prosthesis led to increased average and maximum pressure and decreased contact area. In an experimental test setup, the newly developed total knee arthroplasty without patellar flange showed reduced patello-femoral contact pressure in comparison with a total knee prosthesis with conventional patellofemoral design. This could possibly lead to a lower incidence of anterior knee complaints in patients.

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Brian D. Street and William Gage

Total knee replacement (TKR) is the most common surgical intervention for moderate to severe knee osteoarthritis (OA), reducing pain and activity limitations, as well as improving functional ability. 1 – 5 However, although improved from presurgical levels, persistent deficits in functional

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Fred Brouns, Wim Saris and Heinz Schneider

The addition of carbohydrate and sodium to sport drinks has been recommended to enhance fluid intake and absorption and to delay fatigue. Other electrolytes (E) which are lost through sweating are also commonly added. However, too many E may lead to increased serum E and osmolality levels, which may negatively influence thermoregulation, depress sweating, and cause gastrointestinal distress. On the other hand, drinking large amounts of plain water to compensate sweat loss may induce hyponatremia. Therefore, literature describing sweat E losses was examined in order to estimate average whole-body E loss and to determine an upper limit for replacement of E with sport drinks. Mean E loss was determined from 13 studies, with +1 SD resulting in a hypothetical range for E losses. Correction for net absorption resulted in an upper limit of electrolyte replacement. It is suggested that the E levels in sport rehydration drinks should not exceed the upper limit of the range given.

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Kate E. Webster, Julian A. Feller and Joanne E. Wittwer

This study examined the relationship between balance confidence and function in older adults after knee-replacement surgery. Thirty-six adults (20 men and 16 women age 58–84 years) completed measures of balance confidence, general self-efficacy, and function. Results showed that participants with greater balance confidence had better functional performance and reported fewer difficulties with activities of daily living. General self-efficacy and age were not related to any of the functional measures. Women scored lower than men for all balance-confidence and function measures. These findings highlight the potential value of studying balance-related self-efficacy beliefs in people with knee replacements. Longitudinal studies are now needed to determine whether a change in balance confidence is associated with a change in function and to further explore gender differences.

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Lee E. Brown, Michael Whitehurst and David N. Buchalter

A 67-year-old male underwent bilateral total knee replacement surgery and was subsequently placed on a bilateral isokinetic knee rehabilitation program. Isokinetic knee testing was performed on unilateral dominant (UD; right) and nondominant (UND; left) limbs as well as bilateral limbs (BLs) before and after a three-times-per-week, 8-week protocol during which the patient followed a bilateral isokinetic velocity spectrum (60 to 300°/s) rehabilitation program. The protocol was made possible by the introduction of a new bilateral isokinetic knee attachment developed by the authors. The BL extension and flexion peak torque increased 41% and 51% at 60°/s, respectively. The UD and UND extension peak torque increased 22% and 37%, respectively, while flexion peak torque increased 68% and 52%, respectively. The bilateral deficit decreased with increasing velocity for both extension and flexion. These results demonstrate that a bilateral isokinetic approach to rehabilitation may be a legitimate technique to increase knee extension and flexion peak torque both unilaterally and bilaterally following bilateral total knee replacement surgery.

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Jennifer L. Etnier and Benjamin A. Sibley

The purpose of this study was to examine the interactive effects of hormone-replacement therapy (HRT) and physical activity (PA) on the cognitive performance of older women. Postmenopausal women (n = 101) were recruited to complete a PA questionnaire, provide demographic information, and perform the digit-symbol substitution task (DSST) and the trail-making tests (TMT). Regression analyses were conducted for participants with complete data for each cognitive test (DSST n = 62; TMT n = 69). For both tasks, results indicated that PA and education were positively related and age was negatively related to cognitive performance. The interaction of HRT with PA did not add to the predicted variance of either measure of cognitive performance. This was true even after limiting the HRT users to women using unopposed estrogen. It is concluded that the beneficial relationship between PA and these two measures of cognitive performance in postmenopausal women exists irrespective of HRT use.

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Heather Anne Hayes, Nikelle Hunsaker, Sydney Y. Schaefer, Barry Shultz, Thomas Schenkenberg, Lara A. Boyd, Andrea T. White, Kenneth B. Foreman, Philip Dyer, Rebecca Maletsky and Leland E. Dibble

Deficits in sequence-specific learning (SSL) may be a product of Parkinson’s disease (PD) but this deficit could also be related to dopamine replacement. The purpose of this study was to determine whether dopamine replacement affected acquisition and retention of a standing Continuous Tracking Task in individuals with PD. SSL (difference between random/repeated Root Mean Square Error across trials) was calculated over 2 days of practice and 1 day of retention for 4 groups; 10 healthy young (HY), 10 healthy elders, 10 individuals with PD on, 9 individuals with PD off their usual dosage of dopamine replacement. Improvements in acquisition were observed for all groups; however, only the HY demonstrated retention. Therefore, age appeared to have the largest effect on SSL with no significant effect of medication. Additional research is needed to understand the influence of factors such as practice amount, task difficulty, and dopamine replacement status on SSL deficits during postural tasks.

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David A. Rowe, Matthew T. Mahar, Thomas D. Raedeke and Joanna Lore

The study was undertaken to evaluate (a) the reliability of pedometer data and reactivity of children to wearing a pedometer, (b) the effectiveness of a missing data replacement procedure, and (c) the validity of the Leisure Time Exercise Questionnaire (LTEQ). Six days of pedometer data were collected from 299 middle-school children, followed by administration of the LTEQ. Six days of pedometer data were found to be adequately reliable for research into habitual physical activity (R xx = .79) and no reactivity occurred. Inclusion of weekday and weekend scores is recommended where possible. The individual-centered data-replacement procedure did not adversely affect reliability, so this data-replacement method offers great promise to physical activity researchers who wish to maintain statistical power in their studies. The LTEQ does not appear to measure physical activity similarly to pedometers (r = .05), and researchers should use the LTEQ with caution in children until further research explains this discrepancy.

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John S. Green, Peter W. Grandjean, Shelly Weise, Stephen F. Crouse and J. James Rohack

Although endurance exercise and supplemental estrogen have both been shown to improve serum lipid cardiac risk profiles in postmenopausal women, data regarding a possible synergistic influence are scarce and inconsistent. The purpose of this study was to determine whether such a synergistic influence could be demonstrated. Serum concentrations of total cholesterol (TC), HDL-cholesterol (HDL-C), HDL2-C, HDL3-C, LDL-C, and triglycerides (TG) were obtained from postmenopausal women (N = 45) in each of 4 groups: currently exercising and taking estrogen replacement, exercising and not taking estrogen, sedentary and taking estrogen, and sedentary and not taking estrogen. HDL-C was on average 21% higher (p < .05) and the HDL-C:LDL-C ratio on average 45% higher (p < .05) in the exercise-plus-estrogen group than in any of the other 3 groups. It was concluded that the combination of endurance exercise and estrogen replacement might be associated with better lipid coronary risk profiles in postmenopausal women than either intervention alone.