Strength Research Articles

Detraining and Retraining in Older Adults Following Long-Term Muscle Power or Muscle Strength Specific Training

Training cessation among older adults is associated with the loss of functional ability. However, exercise programs undertaken prior to activity cessation may offer functional protection. In the present study, the residual effects of muscle power or muscle strength training were investigated following extended detraining and subsequent retraining. Thirty-eight healthy independent older adults (65-84 years) entered a 24-week detraining period subsequent to 24 weeks of training. Following detraining, participants recommenced training using either the high-velocity muscle power (HV) or muscle strength (ST) protocol, as undertaken during the initial training period, twice weekly for 12 weeks. Isometric and dynamic muscle strength, muscle power, movement velocity, muscle endurance, electromyographic activity, and the results of a battery of functional performance tasks were assessed. Muscle function and functional performance increased following initial training, however, no group differences were observed. Detraining resulted in similar declines in muscle power and muscle strength for both groups (p <.05) (power, HV 17.8 +/- 1.8%, ST 15.5 +/- 2.2%; and strength, HV 17.1 +/- 2.2%, ST 16.5 +/- 1.8%), with comparable accrual following retraining. No significant changes in functional ability were observed following detraining (average change; HV 3.1 +/- 3.5% and ST 2.1 +/- 3.5%) or retraining. No group differences emerged in this study. Cessation of training resulted in only a modest loss of muscle power and strength that was recouped following 12 weeks of retraining. Importantly, training-induced gains in functional performance were preserved during detraining. The residual effects of power or strength training appear comparable, and both may be suitable exercise modes prior to a period of activity cessation to promote physical independence.

The Effect Of Two Concurrent Training Programs With Different Inter-Session Recovery On Muscular Strength

Attenuated gains in muscular strength acquired via concurrent strength and endurance may be due to a lack of recovery from the high volume of exercise characteristic of concurrent training. PURPOSE: To evaluate the relative effectiveness of two concurrent training regimens, differing only in the duration of the rest between the strength (ST) and endurance training (ET) sessions, on increases in strength. METHODS: Twenty-four physically active, untrained males (21+1.37 years) completed six weeks of training in one of three groups: a same day concurrent training (SDCT - ST & ET 3d/wk), an alternate day concurrent training (ADCT - ST 3 d/wk & ET 3 d/wk), or a strength training only group (STTR - 3 d/wk). Body composition measures (body wt., % body fat, FFM, fat mass), VO2 max, 1RM bench press, and 1RM hack-squat were measured before and after training. RESULTS: A 2-way ANOVA revealed a significant main effect for time with 1RM bench press, 1RM hack-squat, VO2max, and FFM increasing and percent body fat decreasing. There were no significant differences between groups. All data below are expressed as a pre-to post-percent change.CONCLUSIONS: The lack of significant differences between the groups in muscular strength, cardiorespiratory endurance, and body composition does not support the existence of an interference phenomenon in the muscular adaptations to concurrent training.

Muscle Strength and Power, Maximum Oxygen Consumption, and Body Composition in Middle-Aged Short-stature Adults with Childhood-onset Growth Harmone Deficiency

Growth hormone (GH) replacement in adult GH-deficient (GHD) patients is reported to have a long-term beneficial effect on muscle mass and function, these effects being greater in young males and in adult-onset compared with those with childhood-onset GHD. To date, more discordant data are reported on the degree of muscle impairment in untreated GHD patients, due to the large heterogeneity of this syndrome. Muscle maximum total isotonic strength (ST), lower limb maximum power output (W), maximum aerobic capacity (VO(2)max) and body composition (by tetrapolar bio-impedentiometry) were evaluated in seven short-stature adults with childhood-onset GHD and in seven age-matched normal-stature controls with comparable lifestyle and daily physical activity. Significant differences were found in body composition between control subjects and GHD patients, who presented higher adiposity (mean BMI+/-SD: GHD, 27.8+/-5.8 kg/m(2); controls, 22.1+/-0.8 kg/m(2); p=0.047), larger fat mass (GHD, 21.8+/-10.7 kg; controls, 8.8+/-3.5 kg; p=0.008), and lower fat-free mass (GHD, 65.8+/-11.4 %; controls, 87.0+/-6.5 %; p=0.002). In absolute terms, GHD patients attained significantly lower values in ST (GHD, 2479+/-493 N; controls, 4578+/-1476 N; p=0.008), W (GHD, 1092+/-452 W; controls, 1910+/-781 W; p=0.035) and VO(2)max (GHD, 1.68+/-0.40 l/min; controls, 2.67+/-0.84 l/min; p=0.035) than those attained by controls. The differences were still evident when the results were normalized by unit body mass, whereas they disappeared when the parameters were expressed per unit fat-free mass, suggesting for these patients the presence of an intrinsic muscle function in the same range as that of control subjects. Middle-aged and short-stature adults with childhood-onset GHD, who received discontinuous pit-GH substitution therapy only during childhood and have uncorrected long-lasting GHD, still retain a normal intrinsic muscle capability in attaining isotonic strength, generating anaerobic power as well as accomplishing oxidative processes. Nonetheless, it is not known which age-dependent evolution in motor dysfunction could be expected in this subgroup of GHD patients, when ageing processes add up to hormonal deficiencies.

Model for Vacancy-Inducedd0Ferromagnetism in Oxide Compounds

We propose a model with few parameters, for vacancy-induced ferromagnetism based on a correlated model for anions (oxygen orbitals) with random potentials that represent cation vacancies. There is a range of potential strength for which moments appear on oxygen sites neighboring the vacancies. By using techniques which allow us to treat the randomness exactly, we calculate the magnetic couplings between the total moment around each vacancy, the Curie temperature and dynamical correlations as a function of the effective stren gth of the vacancy potential and doping properties, the density of vacancies, as well as the correlation and band width of the host. For physically reasonable parameters this predicts Curie temperatures well above room temperature for small concentrations of vacancies and appropriate parameters. We disc uss our results in relation to questions of stability and reproducibility raised in experiments. To circumvent the difficulties of controlling intrinsic defects, we propose specific non-magnetic host doping that could be, for example, substituted for cations in HfO$_2$ or ZrO$_2$.

On the Afterglow and Host Galaxy of GRB 021004: A Comprehensive Study with theHubble Space Telescope

We report on Hubble Space Telescope (HST) observations of the late-time afterglow and host galaxy of GRB 021004 (z = 2.33). Although this gamma-rayburst (GRB) is one of the best observed so far in terms of sampling in the time domain, multi-wavelength coverage and polarimetric observations, there is large disagreement between different measurements and interpretations of this burst in the literature. We have observed the field of GRB 021004 with the HST at multiple epochs from 3 days until almost 10 months after the burst. With STI S prism and G430L spectroscopy we cover the spectral region from about 2000 Angstrom to 5700 Angstrom corresponding to 600 1700 Angstrom in the rest frame. From the limit on the flux recovery bluewards of the Lyman-limit we constrain the H I column density to be above 1 x 1018 cm-2 (5 sigma). Based on ACS and N ICMOS imaging we find that the afterglow evolved a chromatically within the errors (any variation must be less then 5 percent) during the period of HST observations. The color changes observed by other authors during the first four days must be related to a 'noisy' phenomenon superimposed on an afterglow component with a constant spectral shape. This also means that the cooling break has remained on the blue side of the optical part of the spectrum for at least two weeks after the explosion. The optical to X-ray slope OX is consistent with being the same at 1.4 and 52.4 days after the burst. This indicates that the cooling frequency is constant and hence, according to fireball models, that the circumburst medium has a constant density profile. The late-time slope of the light curve (alpha 2, F nu proportional to t-alpha2) is in the range 2 = 1.8-1.9, although inconsi stent with a single power-law. This could be due to a late-time flattening caused by the transition to non-relativistic expansion or due to excess emission (a 'bump' in the light curve) about 7 days afterburst. The host galaxy is like most previously studied GRB hosts a (very) blue starburst galaxy with no evidence for dust and with strong Ly emission. The star-formation rate of the host is about 10 M solar mass yr-1 based on both the stre ngth of the UV continuum and on the Ly alpha luminosity. The spectral energy distribution of the host implies an age in the range 30-100 Myr for the dominant stellar population.

Gender-related changes in body composition, muscle strength and power output after a short-term multidisciplinary weight loss intervention in morbid obesity

Obese men and women have notably different body composition, which contributes to a different functional motor impairment, but it is unknown whether they respond differently to the same intervention for body weight (BW) reduction and motor capability improvement. The aim of this investigation was to compare changes in body composition, strength production and power output observed in severely obese men and women after a BW reduction intervention, and to test the hypothesis that changes in body composition may be related to changes in motor functionality. Ninety-five obese men and women of the same age (29.3 +/- 7.0 SD yr) and body mass index (41.2 +/- 4.4 kg/m2) participated in a short-term (3 week) mass reduction program (5 days/week) entailing exercise (aerobic and strength training) and energy-restricted diet. BW and body composition, maximum voluntary total isotonic strength (ST), and maximum leg power output (W) were evaluated before and after the program. After the intervention, BW decreased significantly in both men and women, but males lost a significantly higher amount of their initial BW than females (5.12 +/- 0.91 vs 4.27 +/- 1.42%, p<0.01). In men the BW loss was composed by a similar amount of fat mass (FM) and fat-free mass (FFM), whereas women lost FM almost entirely. Both men and women significantly improved ST after the intervention, but no difference in improvement was detected between genders, while W increased significantly in females (p<0.001), and no change was detected in males, although W per unit BW and FFM increased significantly in both genders (p<0.05-0.001). In spite of the positive correlation of ST and W with FFM (p<0.001), there was no detectable relation between the changes in body composition and those in motor performance, the improvement in ST and W being better attributable to factors other than muscle mass change. The present diet/exercise intervention induced significant effects on BW changes and composition as well as on ST and W, with a different impact in males and females.

Gender variations of body composition, muscle strength and power output in morbid obesity

Motor capabilities are reduced in obese (OB) individuals, and this impairment may result also from quantitative variation of muscle mass due to alterations in body composition. This study aims to evaluate the differences in body mass (BM) and composition, as well as in muscle strength (ST) and power output W(.) between OB and NW males and females, and to test the hypothesis that variations in body composition affect muscle performance in OB subjects. Body composition (determined by BIA with a two-compartment model), upper and lower limb maximum ST (evaluated with isotonic machines) and lower limb maximum anaerobic W(.) (measured with a jumping test) were studied in a group of 95 extremely OB subjects (OB: 28 males, 67 females; mean age+/-s.d.: 29.3+/-7.0 y; BMI: 41.2+/-4.4 kg/m(2)) and in a control group of 18 NW voluntary subjects (NW: eight males, 10 females; age: 30.3+/-5.3 y; BMI: 22.6+/-2.1 kg/m(2)). OB male and female subjects differed significantly with increases in BM being attained by a similar contribution of fat mass (FM) and fat-free mass (FFM) in male subjects, but mainly contributed by FM in female subjects. Compared with NW, both OB men and women had a greater amount of FFM (P<0.001) and, since a general linear correlation was found between ST and FFM (ST (N)=64.4 FFM (kg)-190.0, R(2)=0.612, P<0.001), they developed higher values of ST (P<0.05) than their respective NW counterparts. For the same reason, both OB and NW male subjects had higher ST (P<0.001) than their female counterparts. Correction for FFM eliminated all gender- and obesity-related ST differences. On the contrary, in spite of their higher absolute muscle strength, both OB men and women could develop absolute W(.) similar to that of NW subjects, and were notably less powerful per unit BM than NW subjects (P<0.001), women being most affected among the OB. Obesity-related variation in body composition differs considerably by gender, and is responsible for differences in muscle performance: the higher muscle strength observed in OB subjects (both men and women) and in male subjects (both OB and NW) is accounted for by a greater amount of FFM. Nonetheless, biomechanical limitations appear to impair muscle power development during jumping in OB individuals.

Our Bodies, Ourselves for a New Generation: Revising a Feminist Classic

Our Bodies, Ourselves is o ften ca ll ed t he bible of women’s healt h. First p u blis hed 35 y ears ago, t his feminist c lassic has so ld more t han four million co p ies and has been translated into seventeen lan gua ges and Brai ll e. Current ly, groups in Sout h Korea, India, Poland, and severa l ot her countries are wor king on trans lations an d cu ltura l adaptations . Here in North America, I was invited to lead the revision of Our Bodies, Ourselves in t he late summer o f 2003. My se lection as managing editor o f th e new Eng lis h-language edition mar ked a conscious e ffort by Our Bo dies Ourselves (the nonprofi t group also known as the Boston Women’s Health Book Coll ective ) to pass t he prover bial torc h to a younger generation. I was an in fant back in 1969, w hen a group o f women in Boston starte d t he discussions that led to the ori ginal Our Bodies, Ourselves. Many of the women w ho have wor ked wit h me on t his e dition are even younger . When I propose d a pane l for t he National Women’s Stu dies Association conference in 2004, I decided to ask how these younger women, working alongsi de women w ho have known an d love d t he book since its conce p tion, have helpe d to trans form t his c lassic feminist text. Our aim has been to reach the next generation while retainin g the essential stren gths t hat ma ke t he book belove d by longtime fans. Our Bodies, Ourselves wi ll continue to provi de compre hensive, accurate healt h information from a

Synchronization of symmetrically nonlinear-coupled chaotic systems

The synchronization of two symmetrical nonlinear-coupled chaotic systems is discussed. A special nonlinear-coupled term is constructed by suitable separation between linear and nonlinear terms of the chaotic system. The phenomenon of stab le chaotic synchronization has been found in a certain region of the coupled str ength α=05. The stability of the synchronous state is examined by the sta bility criterion of linear systems and the conditional Lyapunov exponent. The Lo renz system and the hyper-chaotic Rssler system are treated as numerical exam ples. It is shown that the proposed method is effective for chaotic synchronizat ion of time-continued systems and hyper-chaotic systems.

Microestrutura e propriedades de porcelanas

A microestrutura de uma porcelana tradicional, queimada a diferentes temperaturas, foi analisada e relacionada com suas propriedades técnicas. Investigou-se por ceramografia a morfologia de fases, determinando-se a presença de quartzo, mulita primária e mulita secundária. Este estudo foi apoiado por análise de microssonda EDX e difratometria de raios X. As propriedades dos corpos-de-prova sinterizados mostram-se fortemente influenciadas pela fase vítrea e pelas fases cristalinas presentes, estas últimas preponderantes na definição da resistência mecânica final e tenacidade das peças.

The Effect of Acute Exercise upon Postprandial Lipemia Following Correction for Plasma Volume Shifts

1489 PURPOSE: To examine the influence of plasma volume (PV) adjustments on our previously reported finding that isocaloric bouts of acute strength (ST) and aerobic training (AT) had no effect on fasting and postprandial plasma lipoprotein concentrations in 13 healthy normolipidemic males (age, 20.9 ± 0.6 years). METHODS: Subjects participated in three postprandial lipemia tests, one control (CON) and the other two 14-hours following isocaloric bouts of ST and AT. During all 3 tests, venous samples were obtained in a 12-hr fasted state and after the consumption of a high fat breakfast (55 g fat, 149 g carbohydrate, 22 g protein). Blood samples were analyzed for plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and glucose. Changes in PV were determined using the fasting CON trial hematocrit (Hct) and hemoglobin (Hb) values as the reference point from which all blood samples from the CON trial and exercise trials were compared. TG was monitored hourly for 6 hours from which the incremental (INCAUC) and total (TOTAUC) areas under the 6-hour TG curve were calculated. Differences between CON, ST and AT trials, with and without PV corrections. RESULTS: Hb was significantly higher in the fasting AT blood sample compared to the fasting CON sample (CON, 11.48 ± 0.78; AT, 14.13 ± 0.65; ST, 13.46 ± 0.53 mg/dl). The AT and ST fasting blood samples displayed 18 and 14 % reductions in PV, respectively. After PV correction there was no effect on fasting plasma TG or HDL-C concentrations. However, fasting plasma TC (CON, 172.5 ± 7.3; AT 138.1 ± 7.5; ST 149.2 ± 8.2 mg/dl) and glucose (CON, 85.9 ± 1.7 AT 70.8 ± 1.5; ST 69.6 ± 1.6 mg/dl) were significantly lower (P<0.05) following both exercise bouts. The 6-hour plasma TG INCAUC (CON, 355.0 ± 60.4; ST 183.5 ± 36.6; AT, 130.3 ± 30.1 mg/dl × 6h) and glucose TOTAUC (CON, 531.6 ± 19.8; ST 432.4 ± 20.1; AT, 419.8 ± 23.2 mg/dl × 6h) were significantly reduced during both exercise trials. CONCLUSION: These data suggest that PV corrections over multiple tests may provide a clearer picture of the effect of exercise treatments upon PPL. Given uncertainty over the exact cause of post exercise PV shifts and the large PV variation between trials in this study it is suggested that fluid and salt intakes be controlled during the 24-hours preceding fat tolerance tests.

The Effect of Acute Exercise upon Postprandial Lipemia Following Correction for Plasma Volume Shifts

1489 PURPOSE: To examine the influence of plasma volume (PV) adjustments on our previously reported finding that isocaloric bouts of acute strength (ST) and aerobic training (AT) had no effect on fasting and postprandial plasma lipoprotein concentrations in 13 healthy normolipidemic males (age, 20.9 ± 0.6 years). METHODS: Subjects participated in three postprandial lipemia tests, one control (CON) and the other two 14-hours following isocaloric bouts of ST and AT. During all 3 tests, venous samples were obtained in a 12-hr fasted state and after the consumption of a high fat breakfast (55 g fat, 149 g carbohydrate, 22 g protein). Blood samples were analyzed for plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and glucose. Changes in PV were determined using the fasting CON trial hematocrit (Hct) and hemoglobin (Hb) values as the reference point from which all blood samples from the CON trial and exercise trials were compared. TG was monitored hourly for 6 hours from which the incremental (INCAUC) and total (TOTAUC) areas under the 6-hour TG curve were calculated. Differences between CON, ST and AT trials, with and without PV corrections. RESULTS: Hb was significantly higher in the fasting AT blood sample compared to the fasting CON sample (CON, 11.48 ± 0.78; AT, 14.13 ± 0.65; ST, 13.46 ± 0.53 mg/dl). The AT and ST fasting blood samples displayed 18 and 14 % reductions in PV, respectively. After PV correction there was no effect on fasting plasma TG or HDL-C concentrations. However, fasting plasma TC (CON, 172.5 ± 7.3; AT 138.1 ± 7.5; ST 149.2 ± 8.2 mg/dl) and glucose (CON, 85.9 ± 1.7 AT 70.8 ± 1.5; ST 69.6 ± 1.6 mg/dl) were significantly lower (P<0.05) following both exercise bouts. The 6-hour plasma TG INCAUC (CON, 355.0 ± 60.4; ST 183.5 ± 36.6; AT, 130.3 ± 30.1 mg/dl × 6h) and glucose TOTAUC (CON, 531.6 ± 19.8; ST 432.4 ± 20.1; AT, 419.8 ± 23.2 mg/dl × 6h) were significantly reduced during both exercise trials. CONCLUSION: These data suggest that PV corrections over multiple tests may provide a clearer picture of the effect of exercise treatments upon PPL. Given uncertainty over the exact cause of post exercise PV shifts and the large PV variation between trials in this study it is suggested that fluid and salt intakes be controlled during the 24-hours preceding fat tolerance tests.

METAMORPHIC EVOLUTION OF SPESSARTINE QUARTZITES (COTICULES) IN THE HIGH-PRESSURE, LOW-TEMPERATURE COMPLEX AT BAHIA MANSA, COASTAL CORDILLERA OF SOUTH-CENTRAL CHILE

Lenses of spessartine quartzites (coticules) are associated with greenschist intercalations in coastal exposures at Bahia Mansa within the mainly metapsammopelitic Western Series, which forms most of the basement in the Coastal Cordillera of central to southern Chile. The chemical compositions of the coticules can be explained by protoliths formed from ferriferous and manganiferous hydrothermal precipitates mixed with aluminous alteration-derived material on top of oceanic crust. The peak conditions of metamorphism were calculated with multivariant reactions: 270–370 °C, 6–8 kbar. A retrograde P–T evolution was marked by decompression to 2 kbar during cooling below 300°C, influx of an external fluid, and strain-free crystallization of retrograde phases. The appearance of “ferriwinchite”, “ferribarroisite” and phengite in coticules and surrounding metabasic roc ks marks the transition from greenschist to epidote blueschist facies. Oscillatory zoning in garnet within the coticules as well a s in epidote and tourmaline in the metabasic rocks seems to be governed by the local chemical environment during prograde growth of minerals. Although the garnet in the coticules formed by a continuous prograde dehydration–decarbonation reaction, the primary fluid inclusions are predominantly hydrous owing to massive influx of fluid during the early stage of decompression. Th e late stage of decompression is bracketed by isochores of primary fluid inclusions that are clearly below peak conditions of metamorphism. This is attributed to a volume increase of the fluid inclusions and stretching of the host minerals during decompression. Higher densities of fluid inclusions in garnet compared to those in quartz are due to differences in yield stren gth between the two minerals. The transient metamorphic gradient of approximately 12 °C/km revealed by the coticules and adjacent metabasic rocks of oceanic origin suggest slow subduction. Penetrative ductile deformation is mainly restricted to the late pro grade and early retrograde P–T path within an accretionary prism.

Welding of 9-12% CR Steels for High Temperature Pressure Part of Power Plants

Alloy Steels exhibiting superior creep rupture stren gth and exce lle n t resistance to thermal fatigue have been developed for use in recent years.

THE EFFECT OF PHYSICIAN'S ADVICE ON ADOLESCENT EXERCISE BEHAVIOR AND FITNESS

551 To evaluate the advice of an office-based physician as a mean of increasing fitness in adolescent patients (12 to 21 years old), something that has not been proved as yet: patients were randomly asigned to a case or a control group matched by sex and age, after visiting the offices of 3 different physicians for a period of 6 months. Both groups were given a questionnaire recording exercise (type, duration (D), frequency (F) and intensity (I) at and outside school and the following measurements were taken: resting blood pressure (RBP) and heart rate (RHR), percent body fat (PBF), flexibility (FX)(“sit and reach” test), strength (ST) (handgrip dinamometry) and cardiorespiratory endurance (CRE) (modified step test). Cases were provided with counseling to maintain (active adolescents), increase (partially active adolescents) or start (inactive adolescents) exercise at the first and six months visits. Questionnaires and measurements were again evaluated after 12 months. A sample of 94 cases and 94 controls (63% males and 37% females) was gathered. At the first visit, there were 36,2% active adolescents in both groups, with no significant differences in fitness measurements between groups. At 12 months, cases had increased the number of active adolescents(43%; p<0,01) and ST (28 to 31 units; p<0,01) and decreased RBP (113/68 to 110/65 mmHg; p<0,01) and PBF (18% to 17%; p<0,04), whereas controls had decreased the number of active adolescents (31%; p<0,01) and increased RHR (71 to 74 bpm; p<0,03) and ST (29 to 30 units; p<0,03). However, there were no significant differences between the groups. Cases significantly increased only in F (1,7 to 2,3 days/week; p<0,02) and in spite of increasing also D and I, and controls decreasing D, F and I, there were important differences at 12 months but they did not reach statistic significance. Physician counseling about exercise was followed by 52% of adolescents cases. Based-office physician's advice about exercise to adolescent patients is of use to increase their exercise levels to a degree resulting in short fitness improvement after a year.

Studies to Measure Cotton Fibre Length, Strength, Micronaire and Colour by vis/NIR Reflectance Spectroscopy. Part II: Principal Components Regression

In Part I of this series, both cotton fibre property and reflectance spectra data on 185 US cottons including four Pimas were analysed by descriptive statistics. In this paper, principal components regression (PCR) models for measuring six properties from the cotton's vis/NIR reflectance spectra are critically examined. These properties are upper-half mean length (UHM), uniformity index (UI), bundle strength (STR), micronaire (MIC) and colour (Rd and +b). The spectra were recorded with a scanning spectrophotometer in the wavelength range from 400 to 2498 nm. A variety of spectral processing options, some of which give improved PCR analysis results, were applied prior to the regressions and allowed for testing of over 100 PCR models. All PCR model results are based on the PRESS statistic by one-out-rotation, a fast approximation of the PRESS statistic (to reduce computer time) or on cluster analysis using separate calibration and validation data sets. The standard error of prediction (SEP) of all the properties except UHM compared well to the reference method precision. The precision of the UHM measure by reflectance spectroscopy was strongly influenced by the sample repack error. The SEP of UHM, UI and STR was improved by excluding the Pimas from the data set.

Development and validation of a physical performance instrument for the functionally impaired elderly: the Physical Disability Index (PDI).

Article describes development of the Physical Disability Index (PDI), an observer-administered, performance-based instrument measuring physical disability in frail-elderly persons without severe cognitive impairment. Sixty-five items in four subscales encompassing Range of Motion (ROM), Strength (STR), Balance (BAL), and Mobility (MOB) were measured. Subjects were randomly selected frail nursing home residents (N = 103) with a Folstein Mini-Mental State Exam (MMSE) score of > or = 11. Using correlation matrices, cluster analysis, and regression techniques, the scale was reduced to 54 items. All individual item values were standardized and aggregated into subscale and summary PDI scores, each with a range of 0-100. Test-retest and interrater reliability were evaluated. Discriminant and convergent validity were established using MMSE, Physical Self-Maintenance Scale (PSMS), and Sickness Impact Profile-Physical Dimension (SIP-PD). PDI is a performance-based instrument that appears to discriminate among frail individuals with differing levels of physical function. Further testing is warranted in other populations of frail-elderly persons to ascertain its applicability and generalizability.

Muscle soreness, swelling, stiffness and strength loss after intense eccentric exercise.

High-intensity eccentric contractions induce performance decrements and delayed onset muscle soreness. The purpose of this investigation was to study the magnitude and time course of such decrements and their interrelationships in 26 young women of mean(s.d.) age 21.4(3.3) years. Subjects performed 70 maximal eccentric contractions of the elbow flexors on a pulley system, specially designed for the study. The non-exercised arm acted as the control. Measures of soreness, tenderness, swelling (SW), relaxed elbow joint angle (RANG) and isometric strength (STR) were taken before exercise, immediately after exercise (AE), analysis of variance and at 24-h intervals for 11 days. There were significant (P < 0.01, analysis of variance) changes in all factors. Peak effects were observed between 24 and 96 h AE. With the exception of STR, which remained lower (P < 0.01), all variables returned to baseline levels by day 11. A non-significant correlation between pain and STR indicated that pain was not a major factor in strength loss. Also, although no pain was evident, RANG was decreased immediately AE. There was no relationship between SW, RANG and pain. The prolonged nature of these symptoms indicates that repair to damaged soft tissue is a slow process. Strength loss is considered particularly important as it continues when protective pain and tenderness have disappeared. This has implications for the therapeutic management of patients with myopathologies and those receiving eccentric exercise for rehabilitation.

Time course of muscle adaptation after high force eccentric exercise

The repeated bout effect on changes in muscle damage indicators was examined in two groups of subjects following two bouts of 70 maximal eccentric actions of the forearm flexors. Fourteen college age female subjects were placed into two groups. The two bouts were separated by 6 weeks (n = 6), and 10 weeks (n = 8). The subjects performed the same amount of work for the bouts. The muscle damage indicators were isometric strength (STR), relaxed elbow joint angle (RANG), flexed elbow joint angle (FANG), perceived muscle soreness ratings (SOR), and plasma creatine kinase activity (CK). These measures were obtained pre-exercise and 5 days following each bout. The first bout showed significant changes in all measures over time for both groups (P less than 0.01). For the 6-week group, significantly smaller changes in RANG (P less than 0.01), SOR (P less than 0.05), and CK (P less than 0.01), as well as significantly faster recoveries (P less than 0.05) for STR and FANG were produced in the second bout. For the 10-week group, significantly smaller changes in RANG (P less than 0.05) and CK (P less than 0.01) were demonstrated by the second bout, but not significant difference was found for STR, FANG, and SOR between bouts 1 and 2. Changes in CK were still significantly smaller than that of the first bout when 6 subjects (3 subjects from each group) performed the same exercise 6 months after the second bout, but no difference in other measures.(ABSTRACT TRUNCATED AT 250 WORDS)

The growth of AA lava flow fields on Mount Etna, Sicily

The historical lavas on Mount Etna provide a large body of data for examining the growth of aa flow fields. A flow field, the final product of an eruption, is composed of one or more flows. Flow generation depends on the ratio SR/SD of crustal retaining strength (SR) to stress driving the lava outward (SD), rate of flow thickening h, and the time for which h is sustained. At low SR/SD, lava advances by simple spreading, and new flows are formed by subdividing about topographic highs (bifurcation). At low h, growing crusts can contain thickening at all values of SR/SD. Overflow of chilled margins can occur at higher sustained h. Increasing SR/SD favors flow propagation by breaching of crusts. Flow growth is examined by extending the Bingham model of Hulme (1974). Cooling and discharge rate along a flow appear to be the main factors controlling the generation of new flows, with the result that long durations and low average effusion rates favor flow fields with large width/length ratios. Bifurcation generates flows randomly. Breaching and overflow generate flows systematically because of their dependence on cooling. With time, therefore, flow field growth evolves from predominant lengthening to widening. Such behavior is evident for Etnean flow fields, which can also be grouped into two populations on the basis of their width/length ratios. These populations may be related to two distinct mechanisms of magma ascent.