Assessing What Matters to People Affected by Alzheimer's Disease: A Quantitative Analysis

INTRODUCTION

In this phase of the ongoing What Matters Most study series, designed to evaluate concepts that are meaningful to people affected by Alzheimer's disease (AD), we quantified the importance of symptoms, impacts, and outcomes of AD to people at risk for or with AD and care partners of people with AD.

METHODS

We administered a web-based survey to individuals at risk for or with AD (Group 1: unimpaired cognition with evidence of AD pathology; Group 2: AD risk factors and subjective cognitive complaints/mild cognitive impairment; Group 3: mild AD) and to care partners of individuals with moderate AD (Group 4) or severe AD (Group 5). Respondents rated the importance of 42 symptoms, impacts, and outcomes on a scale ranging from 1 ("not at all important") to 5 ("extremely important").

RESULTS

Among the 274 respondents (70.4% female; 63.1% white), over half of patient respondents rated all 42 items as "very important" or "extremely important," while care partners rated fewer items as "very important" or "extremely important." Among the three patient groups, the minimum (maximum) mean importance rating for any item was 3.4 (4.6), indicating that all items were at least moderately to very important. Among care partners of people with moderate or severe AD, the minimum (maximum) mean importance rating was 2.1 (4.4), indicating that most items were rated as at least moderately important. Overall, taking medications correctly, not feeling down or depressed, and staying safe had the highest importance ratings among both patients and care partners, regardless of AD phase.

CONCLUSION

Concepts of importance to individuals affected by AD go beyond the common understanding of "cognition" or "function" alone, reflecting a desire to maintain independence, overall physical and mental health, emotional well-being, and safety. Preservation of these attributes may be key to understanding whether interventions deliver clinically meaningful outcomes.

Assessing what matters most to patients with or at risk for Alzheimer's and care partners: a qualitative study evaluating symptoms, impacts, and outcomes

Background

The What Matters Most (WMM) study was initiated to evaluate symptoms, AD-related impacts, treatment-related needs, preferences, and priorities among individuals with or at risk for Alzheimer’s disease (AD) and their care partners. The objective of this qualitative study phase was to identify a comprehensive set of concepts of interest that are meaningful to individuals across the AD continuum.

Methods

Interviews were conducted with 60 clinically referred individuals and care partners across 5 AD stages (n = 12 each): group 1 (non-clinically impaired individuals with AD pathology), group 2 (individuals with mild cognitive impairment and AD pathology), group 3 (individuals with mild AD), group 4 (individuals with moderate AD and their care partners), and group 5 (care partners of individuals with severe AD). Interviews were conducted by experienced interviewers, audio-recorded, and transcribed. Dominant trends were identified in each interview and compared across subsequent interviews to generate themes or patterns in descriptions of AD symptoms, impacts, and desired treatment outcomes.

Results

All participants endorsed current issues related to memory; nearly all participants (n = 55; 92%) across the five groups endorsed symptoms related to communication and language. Groups 1–3 reported an impact on mood/emotions (n = 23; 64%) and a decrease in social activities or outgoingness (n = 17; 47%). Current and future concerns reported by the overall sample included memory (n = 48; 80%), dependence (n = 40; 67%), and “other” concerns (n = 33; 55.0%) (e.g., uncertainty about the future, burdening others). The most desired AD treatment outcomes were improvement or restoration of memory (n = 40; 67%) and stopping AD progression (n = 35; 58.3%). Group-level differences were observed in the symptoms, impacts, and desired treatment outcomes among patients and care partners across the AD continuum.

Conclusions

Cognitive functioning issues—particularly in memory and communication—are present even in preclinical and early-stage AD, including among those without a formal AD diagnosis. While the impacts of AD vary across the disease-severity spectrum, improved memory and disease modification were treatment outcomes considered most important to participants across all 5 AD stages. Neuropsychological assessments traditionally used in AD clinical trials may not evaluate the often-subtle concepts that are important to patients and care partners. Results from this study will inform the second phase of the WMM project—a quantitative study to elicit the relative importance of these concepts of interest to people at risk for and living with AD and their care partners.

Ring-opened aminothienopyridazines as novel tau aggregation inhibitors

Aminothienopyridazines (ATPZs) have demonstrated efficacy, in vitro, as tau protein aggregation inhibitors. Modifications were made to the ATPZ scaffold to determine the importance of certain structural features for activity. More specifically, ring-opened analogues detached at the nitrogen-nitrogen bond of the pyridazine, were synthesized and their inhibitory activity evaluated. Preliminary data suggests that the ring-opened structures retain inhibitory activity, independent of tau oxidation. The structures detailed represent the beginnings of a deconstruction-reconstruction-elaboration study, with the aim of identifying simpler scaffolds, which retain activity and can be optimized in terms of physiochemical properties.

The effects of building design on hazard of first service in Norwegian dairy cows

Reproductive inefficiency is one of the major production and economic constraints on modern dairy farms. The environment affects onset of ovarian activity in a cow postcalving and influences estrus behavior, which in turn affects a stockperson's ability to inseminate her at the correct time. This study used survival analysis to investigate effects of building design and animal factors on the postpartum hazard of first service (HFS) in freestall-housed Norwegian Red cows. The study was performed on 232 Norwegian dairy farms between 2004 and 2007. Data were obtained through on farm measurements and by accessing the Norwegian Dairy Herd Recording System. The final data set contained data on 38,436 calvings and 27,127 services. Univariate Cox proportional hazard analyses showed that herd size and milk yield were positively associated with HFS. Total free accessible area and free accessible area available per cow year were positively associated with the HFS, as was the number of freestalls available per cow. Cows housed on slatted floors had a lower HFS than those housed on solid floors. Conversely, cows housed on rubber floors had a higher HFS than cows on concrete floors. Dead-ending alleyways reduced the hazard of AI after calving. A multivariable Cox proportional hazards model, accounting for herd management by including a frailty term for herd, showed relationships between hazard of postpartum service and explanatory variables. Animals in herds with more than 50 cows had a higher HFS [hazard ratio (HR)=3.0] compared with those in smaller herds. The HFS was also higher (HR=4.3) if more than 8.8 m(2) of space was available per cow year compared with herds in which animals had less space. The HFS after calving increased with parity (parity 2 HR=0.5, parity ≥3 HR=1.7), and was reduced if a lactation began with dystocia (HR=0.82) or was a breed other than Norwegian Red (HR=0.2). The frailty term, herd, was large and highly significant indicating a significant proportion of the variation resides at herd level. The hazard of first insemination decreased with time for all predictive variables, except dystocia. This study shows that providing adequate environmental conditions for estrus behavior is imperative for reproductive efficiency and after herd management factors and time from calving have been accounted for. Thus, optimizing building design for reproductive efficiency is of significant importance when constructing new cattle housing.

The relationship between fatty acid profiles in milk identified by Fourier transform infrared spectroscopy and onset of luteal activity in Norwegian dairy cattle

To investigate the feasibility of milk fatty acids as predictors of onset of luteal activity (OLA), 87 lactations taken from 73 healthy Norwegian Red cattle were surveyed over 2 winter housing seasons. The feasibility of using frozen milk samples for dry-film Fourier transform infrared (FTIR) determination of milk samples was also tested. Morning milk samples were collected thrice weekly (Monday, Wednesday, Friday) for the first 10 wk in milk (WIM). These samples had bronopol (2-bromo-2-nitropropane-1,3-diol) added to them before being frozen at -20°C, thawed, and analyzed by ELISA to determine progesterone concentration and the concentrations of the milk fatty acids C4:0, C14:0, C16:0, C18:0, and cis-9 C18:1 as a proportion of total milk fatty acid content using dry-film FTIR, and averaged by WIM. Onset of luteal activity was defined as the first day that milk progesterone concentrations were >3 ng/mL for 2 successive measurements; the study population was categorized as early (n=47) or late (n=40) OLA, using the median value of 21 DIM as the cutoff. Further milk samples were collected 6 times weekly, from morning and afternoon milkings, these were pooled by WIM, and one proportional sample was analyzed fresh for fat, protein, and lactose content by the dairy company Tine SA, using traditional FTIR spectrography in the wet phase of milk. Daily energy-balance calculations were performed in 42 lactations and averaged by WIM. Animals experiencing late OLA had a more negative energy balance in WIM 1, 3, 4, and 5, with the greatest differences been seen in WIM 3 and 4. A higher proportion of the fatty acids were medium chained, C14:0 and C16:0, in the early than in the late OLA group from WIM 1. In WIM 4, the proportion of total fatty acid content that was C16:0 predicted late OLA, with 74% sensitivity and 80% specificity. The long-chain proportion of the fatty acids C18:0 and cis-9 C18:1 were lower in the early than in the late OLA group. Differences were greatest in WIM 4 and 5. Differences in concentrations of cis-9 C18:1 were seen between the groups from WIM 1. No relationship was seen between OLA and milk concentrations of either protein or fat, or between OLA and the milk fat:protein ratio. The differences in milk fatty acid proportions between the 2 groups are most likely related to differences in energy balance. The study shows that frozen milk samples can be tested for fatty acids by FTIR spectroscopy and that FTIR spectroscopy of milk can be used to provide real-time information about cow reproductive function.

Quantum and thermal effects of dark solitons in a one-dimensional Bose gas

We numerically study the imprinting and dynamics of dark solitons in a bosonic atomic gas in a tightly confined one-dimensional harmonic trap both with and without an optical lattice. Quantum and thermal fluctuations are synthesized within the truncated Wigner approximation in the quasicondensate description. We track the soliton coordinates and calculate position and velocity uncertainties. We find that the phase fluctuations lower the classically predicted soliton speed and seed instabilities. Individual runs show interactions of solitons with sound waves, splitting, and disappearing solitons.

Relationships between visceral, trunk and whole-body adipose tissue weights by cadaver dissection

BACKGROUND

Despite the important association of central adiposity and cardiovascular and other risk factors, there are only three reported values for directly weighed visceral adipose tissue (AT). All other reported values are based on medical imaging techniques.

OBJECTIVE

The study aimed to investigate the relationships between visceral, trunk and total AT weights in older men and women.

METHODS

Data was obtained from the combination of two studies involving the complete dissection of 15 male and 16 female cadavers (age range 55-94 years) and allowed for compartmentation into skin, AT, muscle, bone and a residual component, divided over six body segments: head, trunk, legs and arms. Visceral AT was separated from trunk subcutaneous AT. All tissues were weighed.

RESULTS

Visceral AT weights ranged from 0.3 to 5.8 kg. Mean values were 3.00 +/- 1.52 kg (mean +/- SE) for the men and 3.24 +/- 1.67 kg for the women. These were not significantly different (p = 0.68), but visceral AT weight, expressed as a percentage of total body AT weight was significantly greater (p = 0.02) in the men (16.8 +/- 5.4%) than in the women (12.9 +/- 3.5%). Correlations between visceral AT weight and the weight of subcutaneous AT of the trunk were highly significant (men, r = 0.70, women, r = 0.81, p < 0.005), with similar slopes for the two sexes. The correlation coefficients of visceral with total body AT weights were even greater (men, r = 0.83 and women, r = 0.96, p < 0.0001).

CONCLUSIONS

In this sample of older Belgians, visceral AT is strongly related to total body adiposity, corresponding to an increment of about 200 g of visceral AT for every kilogram of total AT in men and about 180 g in women. Because of this relationship, techniques such as skinfold calipers and ultrasound for assessing whole body fatness from measurement of only the subcutaneous layer are thus able to account for visceral adiposity.

Resting energy expenditure and body mass changes in women during adjuvant chemotherapy for breast cancer

Weight gain is a commonly reported side effect of adjuvant chemotherapy. A change in resting energy expenditure during treatment has been a suggested mechanism for weight gain. We prospectively measured resting energy expenditure, weight change, and body composition (dual-energy x-ray absorptiometry) in 10 women undergoing adjuvant chemotherapy for breast cancer. There was no change in resting energy expenditure across cycles of chemotherapy (P =.78) or from baseline to the end of treatment (1,189.68 +/- 80.27 vs 1,205.76 +/- 56.71 kcal/d; P =.74). Overall, participants did not gain weight across treatment. However, there was an overall trend toward weight gain (66.3 +/- 5.1 vs 68.2 +/- 5.0 kg; P =.09), and participants did show an increase in total fat mass (24.2 +/- 3.8 vs 26.5 +/- 3.2 kg; P =.04), whereas muscle mass remained the same. Although no change in resting energy expenditure was seen, the observed increase in total fat mass is consistent with a decrease in physical activity level commonly reported with adjuvant chemotherapy treatment of breast cancer, and these body composition changes may have important health implications for survivors.

Bright matter-wave soliton collisions in a harmonic trap: regular and chaotic dynamics

Collisions between bright solitary waves in the 1D Gross-Pitaevskii equation with a harmonic potential, which models a trapped atomic Bose-Einstein condensate, are investigated theoretically. A particle analogy for the solitary waves is formulated and shown to be integrable for a two-particle system. The extension to three particles is shown to support chaotic regimes. Good agreement is found between the particle model and simulations of the full wave dynamics, suggesting that the dynamics can be described in terms of solitons both in regular and chaotic regimes, presenting a paradigm for chaos in wave mechanics.

Respiratory-related evoked potential elicited in tracheostomised lung transplant patients

The present study investigated the role of removal of upper airway and lung vagal afferents in the respiratory-related evoked potential (RREP) response to inspiratory occlusions in two patients with a tracheostomy, who had undergone double lung transplantation (DLT). The patients were 1.5 and 3 months post-DLT and surgical placement of the tracheostomy. RREP recordings in response to inspiratory occlusions were obtained under four conditions: mouth breathing ignore trial; mouth breathing attend trial; tracheostomy breathing attend trial; and tracheostomy breathing ignore trial. The RREP peak components, Nf, P1 and N1, were present in both mouth and tracheostomy ignore breathing trials. The P300 was present in both mouth and tracheostomy attend trials. RREP peak latencies were similar between conditions. The peak amplitudes were greater with mouth breathing due to greater occlusion-related inspiratory pressure. These results demonstrate that the respiratory-related evoked potential can be elicited with inspiratory occlusion in the absence of mouth, upper airway and lung vagal afferent input. This suggests that inspiratory occlusion can elicit cortical activity with activation of inspiratory pump mechanoreceptors.

The effect of codeine on the Urge-to-Cough response to inhaled capsaicin

We have shown previously in normal subjects that a sensory measure, the Urge-to-Cough rating, increases at concentrations of inhaled capsaicin that are lower than those necessary to elicit reflex cough. This finding suggests that the Urge-to-Cough may represent an index of the cough response. Research on cough in the human has most often employed challenge with inhaled capsaicin to induce reflex cough. Current measures of cough sensitivity in the human provide no information regarding the intensity of cough. The influence of codeine on cough perceptual sensitivity and the relationship to cough intensity with capsaicin-induced cough in normal subjects has not been evaluated. This study determined the effect of codeine on capsaicin-induced cough perceptual sensitivity and motor response in normal subjects in a double-blind, placebo-controlled, crossover study. This approach investigated the relevance of cough sensitivity, intensity, and sensory modalities in the assessment of cough suppression in humans. This study consisted of three experimental trials: administration of placebo, 30 mg codeine and 60 mg codeine. The study was double-blinded. The order of the three trials was randomized. Respiratory motor pattern was recorded with EMGs from the rectus abdominis, lateral abdominal muscles and eighth intercostal space. The subjects leaned into a fume hood to inspire deeply for 2 s once through a mouthpiece connected to the nebulizer. A modified Borg scale was used to estimate their Urge-to-Cough. The experimental trial consisted of eight test solutions of 0-200 microM capsaicin. Each solution was presented three times in a randomized block order for a total of 24 presentations. The lowest capsaicin concentration to elicit a cough was determined. The lowest capsaicin concentration to elicit an Urge-to-Cough greater than zero was identified. The Urge-to-Cough sensitivity was determined from the log-log slope. For placebo, the Urge-to-Cough was zero with inhalation of the vehicle and no coughs were observed. The threshold capsaicin concentration for subjects to report an Urge-to-Cough was 15.6 microM (+/-2.6 SEM). The capsaicin concentration threshold for eliciting a cough was significantly greater, 39.3 microM (+/-5.6 SEM). As the capsaicin concentration increased, the magnitude estimation of the Urge to-Cough increased. The slope of the log-log relationship for the Urge-to-Cough was 0.94 (+/-0.07 SEM). As the capsaicin concentration increased, the number and intensity of the coughs increased. The administration of 30 and 60 mg codeine had no significant effect on the threshold capsaicin concentration for the Urge-to-Cough. There was also no significant codeine effect on the slope of the log-log Urge-to-Cough relationship. Thirty and sixty milligram codeine had no significant effect on the relationship between the capsaicin concentration and the number and intensity of the coughs. The results of this study demonstrate that the threshold for a subject to perceive an Urge-to-Cough was less than the capsaicin concentration that elicits the cough motor response. There was a direct relationship between the sensory intensity (magnitude estimation of the Urge-to-Cough) and the cough number and intensity. Thus, as the sense of an Urge-to-Cough increased the cough motor response increased. Neither the 30 nor 60 mg codeine affected the perceptual or motor sensitivity to capsaicin-induced cough. These results showed that the initial threshold for responding to capsaicin-induced cough is the perception of an Urge-to-Cough, followed by a motor cough response if the capsaicin is increased above the perceptual threshold. As the capsaicin concentration increases, both the perceptual need to cough and the cough motor response increase. The response of subjects to inhalation of capsaicin consisted of both a sensory component leading to perception of an Urge-to-Cough and motor cough behavior.

Cadaver-assessed validity of anthropometric indicators of adipose tissue distribution

Although the waist-to-hip ratio (WHR) has emerged as the best anthropometric indicator of the body's adipose tissue distribution, it has never been directly validated. Waist and hip girths, and triceps and subscapular skinfold thickness were measured in 12 male and 13 female cadavers aged 55-94 y. Adipose tissue from the upper limbs, lower limbs, subcutaneous trunk and intra-abdominal regions was then separated by dissection and weighed. Adipose volumes were also determined by hydrostatic weighing. The following adipose tissue mass ratios (and corresponding volume ratios) were derived: trunk to sum of lower limbs, trunk to sum of upper and lower limbs, intra-abdominal to sum of lower limbs and intra-abdominal to sum of upper and lower limbs. Centrality index (CI-subscapular-to-triceps skinfold ratio) and WHR were regressed on the tissue mass and volume ratios of the 25 cadavers. WHR was significantly related to mass and volume ratios for the 12 men (R2=36.0-57.5%, P<0.05), except for intra-abdominal to sum of upper and lower limbs (R(2)=26.3%, P=0.09), but none of these relations was significant in the women. CI was significantly related to all mass and volume ratios only for men and women combined (R(2)=16.2-21.8%, P<0.05). The WHR was better related to all mass and volume ratios than the CI. These results, especially the strong association between WHR and the ratio of intra-abdominal to lower limb adipose masses (R(2)=35.4%, P=0.002), demonstrate a clear relation between the selected anthropometric variables (hip and waist girths, and subscapular and triceps skinfolds) and adipose tissue distribution, thus validating the use of WHR as an important predictor of health risk.

Expiratory muscle training increases pressure support in high school band students

An experiment to increase expiratory muscle strength for instrumentalists, using a high-intensity, low-repetition expiratory training method, was conducted with 40 healthy high school band players. Subjects trained five days per week for 2 weeks using four sets of six training breaths for a total of 24 training breaths with a spring-loaded pressure relief valve that provided an adjustable threshold. The training valve pressure was set at 75% of the subject's measured maximum expiratory pressure (up to 80 cm H2O). Results demonstrated that high-intensity, low-repetition expiratory exercises significantly increased expiratory pressure generating capacity in these subjects and the degree of the training effect was similar regardless of the instrument the band member played. The training effect occurred within 2 weeks of initiating expiratory muscle training. Thus, this simple method of expiratory-specific strength training is effective and efficient for increasing expiratory pressure support in high school band students and has possibilities of a respiratory support device for many high pressure generating purposes. The potential mechanisms of the training effect are discussed.

The effect of maximal exercise on temporal summation of second pain (windup) in patients with fibromyalgia syndrome

Exercise activates endogenous opioid and adrenergic systems, but attenuation of experimental pain by exercise has not been shown consistently. In this study, effects of exercise on temporal summation of late pain responses to stimulation of unmyelinated (C) nociceptors were assessed. When a preheated thermode was applied repetitively to glabrous skin of the hand in a series of brief contacts at rates of 0.2 to 0.5 Hz, the perceived intensity of late thermal sensations increased after successive contacts. This summation of pain sensations provides information regarding the status of central opioid and N-methyl-D-aspartate receptor systems. For normal subjects, temporal summation of late pain sensations was substantially attenuated when testing began 1.5 or 10 minutes after exercise. Individuals diagnosed with fibromyalgia syndrome (FMS) report generalized chronic pain that is increased after exercise. Therefore, we hypothesized that strenuous exercise would increase summation of late pain sensations in this cohort. Patients with FMS and control subjects exerted to similarly high metabolic rates, as shown by physiologic monitoring. Ratings of late pain sensations increased for patients with FMS after exercise, an effect opposite to a decrease in ratings for age/sex-matched control subjects. In contrast to this result for experimentally induced pain, clinical pain ratings were not substantially altered after strenuous exercise by patients with FMS.

Temporal relationships of self-efficacy and social support as predictors of adherence in a 6-month strength-training program for older women

The present study investigated how self-efficacy and social support predicted adherence to a strength training program for elderly women over two time periods in the initial 6 mo. of the program. Participants were 30 elderly women volunteers aged 75 to 80 who completed measures of barrier self-efficacy and general social support at baseline and 3 mo. later. Social support from the program was also measured at 3 mo. Adherence to the program was measured by attendance. Hierarchical regression equations were utilized to identify the contributions of self-efficacy and social support for adherence at 0 to 3 mo. and 4 to 6 mo. For prediction of the first 3 mo. of adherence, both self-efficacy and social support contributed significant unique variance towards the total explained variance of 36%. For the 4- to 6-mo. period, self-efficacy explained significant (12%) variance in adherence even when controlling for the previous 3-mo. adherence. Inclusion of general social support and social support from the program, however, did not account for significant variance. Researchers must continue to examine self-efficacy and social support in exercise adherence within various time periods among older adults to develop effective intervention strategies.

Can sedentary adults accurately recall the intensity of their physical activity?

BACKGROUND

Physical activity, in particular vigorous activity (i.e., > or =6 METs), lowers mortality from chronic diseases such as cardiovascular disease (CVD). The 7-Day Physical Activity Recall (PAR), a self-administered activity log (LOG), and heart rate monitoring (HR) were used to quantify activity patterns among sedentary adults. We hypothesized that individuals in this population could accurately estimate the duration, but not the intensity, of their activity.

METHODS

Sedentary adults (n = 94, 47.8 +/- 7.1 years) completed two PARs 1 week apart and underwent HR monitoring while completing a LOG for 1 day during the PAR assessment interval.

RESULTS

The relationship between PARs (kcal. kg(-1). day(-1) ) was significant (r = 0.80, 95% CI 0.68-0.87) among individuals (n = 63) reporting "typical" activity patterns and among all individuals (n = 94) reporting "typical" and "not typical" activity patterns combined (r = 0.44, 95% CI 0.26-0.59). Quantity of moderate activity was greater (P = 0.0001) on PAR and LOG compared to that measured by HR. Quantity of hard (vigorous) activity was also greater (P = 0.019) on LOG compared to that measured by HR.

CONCLUSIONS

Sedentary adults tend to overestimate the intensity of their activity, specifically for moderate activity. Furthermore, the aerobic capacity of our sedentary adult sample (about 7.3 METs) suggests that the definition of a threshold intensity level of activity necessary to reduce mortality from CVD should be reexamined, because a value of > or =6 METs appears to be too high in this population.

Calcium accretion in girls and boys during puberty: a longitudinal analysis

The primary purpose of this study was to estimate the magnitude and variability of peak calcium accretion rates in the skeletons of healthy white adolescents. Total-body bone mineral content (BMC) was measured annually on six occasions by dual-energy X-ray absorptiometry (DXA; Hologic 2000, array mode), a BMC velocity curve was generated for each child by a cubic spline fit, and peak accretion rates were determined. Anthropometric measures were collected every 6 months and a 24-h dietary recall was recorded two to three times per year. Of the 113 boys and 115 girls initially enrolled in the study, 60 boys and 53 girls who had peak height velocity (PHV) and peak BMC velocity values were used in this longitudinal analysis. When the individual BMC velocity curves were aligned on the age of peak bone mineral velocity, the resulting mean peak bone mineral accrual rate was 407 g/year for boys (SD, 92 g/year; range, 226-651 g/year) and 322 g/year for girls (SD, 66 g/year; range, 194-520 g/year). Using 32.2% as the fraction of calcium in bone mineral, as determined by neutron activation analysis (Ellis et al., J Bone Miner Res 1996;11:843-848), these corresponded to peak calcium accretion rates of 359 mg/day for boys (81 mg/day; 199-574 mg/day) and 284 mg/day for girls (58 mg/day; 171-459 mg/day). These longitudinal results are 27-34% higher than our previous cross-sectional analysis in which we reported mean values of 282 mg/day for boys and 212 mg/day for girls (Martin et al., Am J Clin Nutr 1997;66:611-615). Mean age of peak calcium accretion was 14.0 years for the boys (1.0 years; 12.0-15.9 years), and 12.5 years for the girls (0.9 years; 10.5-14.6 years). Dietary calcium intake, determined as the mean of all assessments up to the age of peak accretion was 1140 mg/day (SD, 392 mg/day) for boys and 1113 mg/day (SD, 378 mg/day) for girls. We estimate that 26% of adult calcium is laid down during the 2 adolescent years of peak skeletal growth. This period of rapid growth requires high accretion rates of calcium, achieved in part by increased retention efficiency of dietary calcium.

Inspiratory strengthening effect on resistive load detection and magnitude estimation

PURPOSE

This study investigated effects of inspiratory muscle training (IMT) on maximal inspiratory pressure (MIP), magnitude estimation (ME), and load detection (LD) of external resistive loads (deltaR) in healthy subjects.

METHODS

Ten adult volunteers IMT trained 5 d x wk(-1) for 4 wk. A training set consisted of six inspiratory efforts at 75% of MIP; daily training trials consisted of four sets. ME was calculated by linear regression, with actual and estimated deltaR loads plotted on log-log scale. LD was calculated by determining deltaR50/Ro fraction. Dependent measures were taken pre- and post-IMT.

RESULTS

MIP significantly increased from 87 to 139 cmH2O pre- to post-IMT, respectively. ME for individual loads significantly decreased post-IMT for all but the highest deltaR. There was no significant difference in LD deltaR50/Ro, post-IMT.

CONCLUSIONS

The results demonstrate that inspiratory muscle strength gains were associated with decreased ME of deltaRs without changing LD deltaR50/Ro. This suggests that the mechanisms mediating the detection of deltaRs may be different than the mechanisms for estimating deltaR size.

Detrimental effects of short-term glucocorticoid use on the rat diaphragm

BACKGROUND AND PURPOSE

The purpose of this study was to determine the effect of short-term, high doses of glucocorticoids on both body and diaphragm weights as well as contractile characteristics of the rat diaphragm.

SUBJECTS

Adult, female Sprague-Dawley rats were divided into 2 groups: a control group (n=16) and a prednisolone group (n=16).

METHODS

The prednisolone group received prednisolone at a dosage of 5 mg/kg, and the control group received sham saline injections for 5 days. Animals were weighed prior to and after completion of the drug injection period. At the completion of the drug injection period, the animals were sacrificed, and the diaphragm, soleus, and extensor digitorum longus muscles were removed and weighed. A small strip of the costal diaphragm was connected to a force transducer, and the following contractile characteristics were measured: maximal specific isometric tetanic tension, peak isometric twitch specific tension, one-half relaxation time, and time to peak tension.

RESULTS

Both body and diaphragm weights decreased by 15% in the prednisolone group as compared with the control group. Maximal specific isometric tetanic tension was reduced 13% in the prednisolone group as compared with the control group. There was no difference in any twitch contractile characteristics between the 2 groups.

CONCLUSION AND DISCUSSION

These data support the hypothesis that glucocorticoid treatment over a 5-day period results in a decrease in specific tension as well as diaphragm and body weight. These results may have implications for the treatment of patients receiving high doses of glucocorticoids for acute medical conditions.

Effects of one year of resistance training on the relation between muscular strength and bone density in elderly women

OBJECTIVES

There is a paucity of long term studies on exercise training in elderly women. The purpose of this study was to investigate the effects of one year of progressive resistance exercise (PRE) on dynamic muscular strength and the relations to bone mineral density (BMD) in elderly women.

METHODS

Forty four healthy sedentary women (mean age 68.8 years) volunteered for this study and were randomly assigned to either an exercise group or a control group. The exercise group were involved in three one hour sessions a week for 52 weeks of supervised PRE to strengthen the large muscle groups of the body, while the control group were instructed to continue their normal lifestyle. The exercise circuit included three sets of eight repetitions at 75% of one repetition maximum focused on the large muscle groups. BMD was measured by dual energy x ray absoptiometry (Lunar DPX) at the lumbar spine and at three sites in the proximal femur. Other selected parameters of physical fitness were also measured.

RESULTS

Statistical analyses (analysis of covariance) showed significant strength gains (p < 0.01) in bilateral bench press (> 29%), bilateral leg press (> 19%), and unilateral biceps curl (> 20%). No significant difference between groups was evident in body weight, grip strength, flexibility, waist to hip ratio, or the sum of eight skinfolds. Significant relations (p < 0.05) were recorded between dynamic leg strength and the BMD of the femoral neck, Ward's triangle, and the lumbar spine.

CONCLUSIONS

Significant strength changes, after one year of PRE, were evident in elderly women, and the muscle increases may parallel changes in BMD; however, correlation coefficients were moderate.

Factors associated with exercise adherence among older adults. An individual perspective

This paper reviews the literature concerning factors at the individual level associated with regular exercise among older adults. Twenty-seven cross-sectional and 14 prospective/longitudinal studies met the inclusion criteria of a mean participant age of 65 years or older. The findings are summarised by demographics, exercise experience, exercise knowledge, physiological factors, psychological factors, activity preferences and perceived social influences. In general, education and exercise history correlate positively with regular exercise, while perceived physical frailty and poor health may provide the greatest barrier to exercise adoption and adherence in the elderly. Social-cognitive theories identify several constructs that correlate with the regular exercise behaviour of older adults, such as exercise attitude, perceived behavioural control/self-efficacy, perceived social support and perceived benefits/barriers to continued activity. As well, stage modelling may provide additional information about the readiness for regular exercise behaviour among older adults. However, relatively few studies among older adults exist compared with middle-aged and younger adults. Further, the majority of current research consists of cross-sectional designs or short prospective exercise trials among motivated volunteers that may lack external validity. Future research utilising longitudinal and prospective designs with representative samples of older adults will provide a better understanding of significant causal associations between individual factors and regular exercise behaviour.

A new formula for population-based estimation of whole body muscle mass in males

A new equation to estimate muscle mass in males was developed using parameters common to the 1981 Canada Fitness Survey and the male cadaver data of Martin et al. (1990b). The cadavers (N = 12) were randomly divided into two groups. The equation was developed on cadaver Group A and then validated on Group B. Once the equation with the most suitable variables was validated on Group B, it was redeveloped on combined data from Groups A and B. The final equation is as follows: muscle mass (gm) = Ht (0.031MUThG2 + 0.064CCG2 + 0.089CAG2) - 3,006; adjusted R2 = .96, SEE = 1,488 gm, F = 87.5, p = .0001. Variables (in cm) were Ht, height; MUThG, modified upper thigh girth; CCG, corrected calf girth; and CAG, corrected arm girth. The predictive ability of this equation was comparable to the original equation of Martin et al. (1990b) and can be a valuable tool for muscle mass estimation of male subjects in the 1981 Canada Fitness Survey.