Driving safety improves after individualized training: An RCT involving older drivers in an urban area.

Objective: This study aimed to reproduce the results of a previous investigation on the safety benefits of individualized training for older drivers. We modified our method to address validity and generalizability issues. Methods: Older drivers were randomly assigned to one of the 3 arms: (1) education alone, (2) education + on road training, and (3) education + on road + simulator training. Older drivers were recruited from a larger urban community. At the pre- and posttests (separated by 4 to 8 weeks) participants followed driving directions using a Global Positioning System (GPS) navigation system. Results: Our findings support the positive influence of individualized on-road training for urban-dwelling older drivers. Overall, driving safety improved among drivers who received on-road training over those who were only exposed to an education session, F(1, 40) = 11.66, P = .001 (26% reduction in total unsafe driving actions [UDAs]). Statistically significant improvements were observed on observation UDAs (e.g., scanning at intersections, etc.), compliance UDAs (e.g., incomplete stop), and procedural UDAs (e.g., position in lane). Conclusion: This study adds to the growing evidence base in support of individualized older driver training to optimize older drivers' safety and promote continued safe driving.

Are older drivers' driving patterns during an on-road driving task representative of their real-world driving patterns?

OBJECTIVE: The current study investigated whether older drivers' driving patterns during a customized on-road driving task were representative of their real-world driving patterns. METHODS: Two hundred and eight participants (male: 68.80%; mean age = 81.52 years, SD = 3.37 years, range = 76.00-96.00 years) completed a customized on-road driving task that commenced from their home and was conducted in their own vehicle. Participants' real-world driving patterns for the preceding 4-month period were also collected via an in-car recording device (ICRD) that was installed in each participant's vehicle. RESULTS: During the 4-month period prior to completing the on-road driving task, participants' median real-world driving trip distance was 2.66 km (interquartile range [IQR] = 1.14-5.79 km) and their median on-road driving task trip distance was 4.41 km (IQR = 2.83-6.35 km). Most participants' on-road driving task trip distances were classified as representative of their real-world driving trip distances (95.2%, n = 198). CONCLUSIONS: These findings suggest that most older drivers were able to devise a driving route that was representative of their real-world driving trip distance. Future research will examine whether additional aspects of the on-road driving task (e.g., average speed, proportion of trips in different speed zones) are representative of participants' real-world driving patterns.

Reinforcements in avian wing bones: Experiments, analysis, and modeling.

Almost all species of modern birds are capable of flight; the mechanical competency of their wings and the rigidity of their skeletal system evolved to enable this outstanding feat. One of the most interesting examples of structural adaptation in birds is the internal structure of their wing bones. In flying birds, bones need to be sufficiently strong and stiff to withstand forces during takeoff, flight, and landing, with a minimum of weight. The cross-sectional morphology and presence of reinforcing structures (struts and ridges) found within bird wing bones vary from species to species, depending on how the wings are utilized. It is shown that both morphology and internal features increases the resistance to flexure and torsion with a minimum weight penalty. Prototypes of reinforcing struts fabricated by 3D printing were tested in diametral compression and torsion to validate the concept. In compression, the ovalization decreased through the insertion of struts, while they had no effect on torsional resistance. An elastic model of a circular ring reinforced by horizontal and vertical struts is developed to explain the compressive stiffening response of the ring caused by differently oriented struts.

Development and evaluation of a driving observation schedule (DOS) to study everyday driving performance of older drivers.

This paper describes the development and evaluation of an on-road procedure, the Driving Observation Schedule (DOS), for monitoring individual driving behavior. DOS was developed for use in the Candrive/Ozcandrive five-year prospective study of older drivers. Key features included observations in drivers' own vehicles, in familiar environments chosen by the driver, with start/end points at their own homes. Participants were 33 drivers aged 75+ years, who drove their selected route with observations recorded during intersection negotiation, lane-changing, merging, low speed maneuvers and maneuver-free driving. Driving behaviors were scored by a specialist occupational therapy driving assessor and another trained observer. Drivers also completed a post-drive survey about the acceptability of DOS. Vehicle position, speed, distance and specific roadways traveled were recorded by an in-vehicle device installed in the participant's vehicle; this device was also used to monitor participants' driving over several months, allowing comparison of DOS trips with their everyday driving. Inter-rater reliability and DOS feasibility, acceptability and ecological validity are reported here. On average, drivers completed the DOS trip in 30.48min (SD=7.99). Inter-rater reliability measures indicated strong agreement between the trained and the expert observers: intra-class correlations (ICC)=0.905, CI 95% 0.747-0.965, p<0.0001; Pearson product correlation, r (18)=.83, p<0.05. Standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV) measures were consistently small (3.0, 2.9 & 3.3%, respectively). Most participants reported being 'completely at ease' (82%) with the driving task and 'highly familiar with the route' (97%). Vehicle data showed that DOS trips were similar to participants' everyday driving trips in roads used, roadway speed limits, drivers' average speed and speed limit compliance. In summary, preliminary findings suggest that DOS can be scored reliably, is of feasible duration, is acceptable to drivers and representative of everyday driving. Pending further research with a larger sample and other observers, DOS holds promise as a means of quantifying and monitoring changes in older drivers' performance in environments typical of their everyday driving.

Structural parameters of the vastus medialis muscle.

This research was designed to evaluate musculoskeletal anatomy of the quadriceps region relative to the patellofemoral joint. The hypothesis for the study was that the oblique portion (VMO) of the vastus medialis muscle (VM) is anatomically positioned to function primarily as an active medial stabilizer of the patella. Because many clinicians believe that the VMO functions independently as an active medial stabilizer of the patellofemoral joint (PFJ), PFJ rehabilitation protocols commonly target the VMO in an attempt to restore normal joint mechanics. It is unclear whether this purported selective function is supported by the underlying anatomical structure. Through dissection of 32 limbs from 24 intact cadavers with normal patellar alignment, data were collected on VM fiber alignment and innervation, the presence of fascial plane, and the length of VM about the patella. Statistical analyses demonstrated that the oblique and long heads of the VM muscle had significantly different (P < 0.05) angles of fiber orientation, as expected. When measurements were taken relative to a vertical axis (standardizing limb alignment between cadavers), the difference in fiber angles between oblique and long heads of the VM was reduced significantly. Additionally, < 10% of the length of the VM muscle inserted directly on the medial aspect of the patella, and there was no anatomical evidence of a fascial plane or separate innervation for the oblique and long heads of the VM. The results of the study did not support the hypothesis that the VMO is anatomically positioned to function primarily as an active medial stabilizer of the patella.

Enzyme activities in the tibialis anterior muscle of young moderately active men and women: relationship with body composition, muscle cross-sectional area and fibre type composition.

The aims of this study were (i) to assess the differences between men and women in maximal activities of selected enzymes of aerobic and anaerobic pathways involved in skeletal muscle energy production, and (ii) to assess the relationships between maximal enzyme activities, body composition, muscle cross-sectional area (CSA) and fibre type composition. Muscle biopsies were obtained from the tibialis anterior (TA) muscle of 15 men and 15 women (age 20-31 years) with comparable physical activity levels. The muscle CSA was determined by magnetic resonance imaging (MRI). Maximal activities of lactate dehydrogenase (LDH), phosphofructokinase (PFK), beta-hydroxyacyl-coenzyme A dehydrogenase (HAD), succinate dehydrogenase (SDH) and citrate synthase (CS), were assayed spectrophotometrically. The proportion, mean area and relative area (proportion x area) of type 1 and type 2 fibres were determined from muscle biopsies prepared for enzyme histochemistry [myofibrillar adenosine triphosphatase (mATPase)]. The men were significantly taller (+6.6%; P < 0.001) and heavier (+19.1%; P < 0.001), had significantly larger muscle CSA (+19.0%; P < 0.001) and significantly larger areas and relative areas of both type 1 and type 2 fibres (+20.5-31.4%; P = 0.007 to P < 0.001). The men had significantly higher maximal enzyme activities than women for LDH (+27.6%; P = 0.007) and PFK (+25.5%; P = 0.003). There were no significant differences between the men and the women in the activities of HAD (+3.6%; ns), CS (+21.1%; P = 0.084) and SDH (+7.6%; ns). There were significant relationships between height and LDH (r = 0.41; P = 0.023), height and PFK (r = 0.41; P = 0.025), weight and LDH (r = 0.45; P = 0.013), and weight and PFK (r = 0.39; P = 0.032). The relationships were significant between the muscle CSA and the activities of LDH (r = 0.61; P < 0.001) and PFK (r = 0.56; P = 0.001), and between the relative area of type 2 fibres and the activities of LDH (r = 0.49; P = 0.006) and PFK (r = 0.42; P = 0.023). There were no significant relationships between HAD, CS and SDH, and height, weight, muscle CSA and fibre type composition, respectively. These data indicate that the higher maximal activities of LDH and PFK in men are related to the height, weight, muscle CSA and the relative area of type 2 fibres, which are all significantly larger in men than women.

Capillary supply of the tibialis anterior muscle in young, healthy, and moderately active men and women.

Tibialis anterior muscle biopsies from moderately active men and women (21-30 yr; n = 30) were examined to determine potential gender differences in capillarization. The fiber type proportions [type I (T1) approximately 73%] were unaffected by gender. The men (M) had significantly (P < 0.001) larger fibers than the women (W), with a greater gender effect for type II (T2) fibers (P < 0.001). The M and W had similar capillary densities (CD approximately 390 capillaries/mm2), but the capillaries-to-fiber ratio (C/F) was higher in the M (M = 2.20 +/- 0.35, W = 1.66 +/- 0.32; P < 0.01). Capillary contacts (CC) were higher in T2 than T1 for the M (P < 0.01), but not W, and M had greater CC (P < 0.001). Both fiber area per capillary (FA/C) and fiber perimeter per capillary (FP/C) indicated that T1 fibers had greater capillarization than T2 fibers (P < 0.001). There were no gender differences in T1 FA/C and T2 FA/C or T1 FP/C, but a gender difference existed for T2 FP/C (M = 60.5 +/- 10.9, W = 70.6 +/- 13.4; P < 0.01). The gender difference for C/F could be explained by fiber size; however, the physiological implications of the difference in T2 FP/C remains to be determined. In conclusion, despite gender differences for fiber size, overall, capillarization was similar between the men and women.

Ankle dorsiflexor muscle performance in healthy young men and women: reliability of eccentric peak torque and work measurements.

The aims of this study were: (i) to assess the test-retest intrarater reliability of eccentric ankle dorsiflexor muscle performance in young healthy men and women using the Biodex dynamometer; and (ii) to examine different statistical indices for the interpretation of reliability. Thirty men and women (age 22.5 +/- 2.5 years, mean +/- S.D.) performed three maximal eccentric contractions at 30 degrees/second and 90 degrees/second, with 7-10 days between test sessions. Reliability was evaluated with three intraclass correlation coefficients (ICC1,1, ICC2,1 and ICC3,1), and was excellent for peak torque (ICC 0.90-0.96) and good to excellent for work (ICC 0.69-0.83), with no discernible differences among the three ICCs. Method errors, assessed by the standard error of the measurement (S.E.M.) and S.E.M.%, were low. The Bland & Altman graphs and analyses indicated no significant systematic bias in the data. In conclusion, measurements of eccentric ankle dorsiflexor muscle performance in young healthy individuals using the Biodex are highly reliable.

The effects of strength training on sarcopenia.

In the past decade strength training has been investigated extensively as a means of reversing the muscle mass loss that occurs with aging (sarcopenia). High intensity resistance training (HIRT) has led to increased protein synthesis, along with muscle hypertrophy measured at the whole body, whole muscle, and muscle fibre levels, in older adults. Typically, the strength increments associated with HIRT have been much larger than the hypertrophic response. However, most HIRT periods have been quite short. Less is known about the long-term hypertrophic response to HIRT in older adults. In order to lessen the effects of sarcopenia, HIRT should continue over the long term in older adults, to improve functional performance and health.

Potential mechanisms of human natural killer cell expansion in vivo during low-dose IL-2 therapy.

The continuous, in vivo infusion of low-dose IL-2 selectively expands the absolute number of human natural killer (NK) cells after 4-6 weeks of therapy. The mechanism responsible for this expansion is unknown and was examined in this study. NK cells cultured at low concentrations of IL-2, comparable to those found during in vivo therapy, proliferate for 6 days and then exit the cell cycle. However, NK cells in vivo did not traverse the S/G(2)/M phase of the cell cycle during low-dose IL-2 therapy. Low concentrations of IL-2 delay programmed cell death of NK cells but have the same effect on resting T cells that do not expand in vivo. When CD34(+) bone marrow hematopoietic progenitor cells are cultured for 21 days with low concentrations of IL-2, they differentiate into CD56(+)CD3(-) NK cells, not T cells. Thus, the selective expansion of human NK cells during continuous in vivo infusion of low-dose IL-2 likely results from enhanced NK-cell differentiation from bone marrow progenitors, combined with an IL-2-dependent delay in NK-cell death, rather than proliferation of mature NK cells in the periphery.

Reliability of isokinetic ankle dorsiflexor strength measurements in healthy young men and women.

The purposes of this study were: (i) to determine the test-retest reliability of isokinetic ankle dorsiflexor strength measurements in young healthy adults using the Biodex dynamometer, and (ii) to examine several statistical measures for the interpretation of reliability. Thirty men and women (mean age 23 +/- 3 years) performed three maximal concentric contractions at 30 degrees/s, 60 degrees/s, 90 degrees/s, 120 degrees/s and 150 degrees/s. Reliability of peak torque, work and torque at a specific time were assessed by calculating the intraclass correlation coefficient (ICC 2,1), Pearson product moment correlation coefficient (r), standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV), and by plotting the differences between observations against their means. Isokinetic tests of ankle dorsiflexor strength in healthy young adults using the Biodex dynamometer were highly reliable (ICC 0.61-0.93). It is recommended that test-retest reliability analyses include the ICC and assessments of measurement errors (SEM, ME or CV), as well as graphs to indicate any systematic variations in the data.

Longitudinal study of the contractile and electrical properties of single human thenar motor units.

Serial motor unit number estimates have shed important light on the extent and rates of motoneuron losses in aging and amyotrophic lateral sclerosis. However, the estimates alone provide few clues to the health and functional status of surviving motor units. A reliable means for assessing the functional status of the surviving motor units would therefore by a welcome addition to our present tools for studying motor units. Examining the physiological properties of samples of motor units drawn at intervals during the course of a motoneuronal disease suffers from the important limitation that the samples may not be representative of one another. The latter problem could be circumvented by serially studying the same motor units. This study describes a noninvasive technique capable of longitudinally tracking the contractile and electrical properties of specific single thenar motor units in healthy subjects, in some instances over several years. The technique proved to be reasonably reliable and provided information on a wide range of contractile and electrical properties of motor units. Such an approach could serve as a potentially powerful and sensitive means of studying the life histories of single motor units in aging, diseases of the motoneuron, and in the latter instances, the responses of the motoneurons to treatment.

Eccentric peak torque of the plantar and dorsiflexors is maintained in older women.

Although a relative preservation of eccentric (ECC) strength with age has been reported previously, this phenomenon has not been studied in lower leg muscles. Concentric (CONC) and ECC plantar (PF) and dorsiflexion (DF) in healthy active older women (OW; n = 16, age = 67 +/- 4 years) and younger women (YW; n = 16, age = 27 +/- 4 years) were studied. Passive resistive torque of the plantar flexors and average rate of torque development (RTD) for both DF and PF were also measured. The OW had CONC peak torques that were 74% and 89% of the YW for PF and DF, whereas ECC peak torques were 97% and 100% of the YW. ECC torque patterns were almost identical for both groups, but there were significant differences for passive resistive torque (OW > YW; p < .01) and CONC RTD (OW < YW; p < .05). While increased passive resistive torque did not prove to be influential in maintaining ECC strength with age, it had a negative effect on CONC DF function.

Standing strength training of the ankle plantar and dorsiflexors in older women, using concentric and eccentric contractions.

Many studies have reported strength gains in older adults following high-intensity resistance training. However, the muscle contraction types examined have been primarily isometric (static) or concentric (CONC; shortening). Less is known about how eccentric (ECC) strength in older adults responds to training or about the efficacy of ECC contractions as training stimuli in these subjects, even though muscle contractions of this type are performed in most training regimens and daily physical activities. In this study, 15 physically active, healthy older women [68 (5) years; mean (SD)] completed an 8-week resistance training program of two sessions per week. Training consisted of three sets of eight repetitions of CONC ankle plantar flexion (PF) and ECC dorsiflexion (DF), at greater than 80% of the initial peak torque, in a standing position only. Subjects were tested in standing and supine positions for: (1) strength over a range of 10 degrees DF to 20 degrees PF for both CONC and ECC; DF and PF (2) passive resistive torque of the plantar flexors at 6 degrees/s; and (3) DF and PF rate of torque development. All strength testing and training was done at 30 degrees/s. Significant increases (P < 0.01) were found for both CONC DF (increases 30%) and ECC DF (increases 17%) peak torque in the standing position. No significant changes occurred for DF strength as measured with the subjects in the supine position, PF strength in either position, passive resistive torque, or rate of torque development. In summary, strength gains occurred only in the dorsiflexors, which were trained using ECC contractions. Improvements in DF strength were specific to the position of training, which has implications for the transferability of strength gains to functional tasks such as maintaining gait.

Development of a home ankle exerciser.

A portable, lightweight home ankle exerciser was designed and built by the Biomedical Engineering Department of University Hospital in London, Ontario, Canada. The ankle exerciser incorporates several unique features that overcomes the drawbacks of exercise equipment presently available. For optimal muscle strengthening, the resistance offered by the device matches the strength curve of the ankle muscles. The magnitude of the resistance can be widely varied to accommodate any subject. Resistance is generated by a slip clutch rather than by springs or weights which can be cumbersome and potentially dangerous. One of the considerations in the design of the ankle exerciser was to monitor subject compliance with the exercise regimen. This is accomplished with a battery-operated monitoring unit mounted on the device. The exerciser is instrumented with a battery-powered torque transducer and digital display unit that enables the subject and assessor to monitor the exercise resistance level at a glance.

A method of measuring standing isokinetic plantar and dorsiflexion peak torques.

Different methods have been used for concentric (CONC) isokinetic testing of ankle dorsiflexion (DF) and plantar flexion (PF). However, little information is available on either the reliability of these protocols or eccentric (ECC) torque production. As well, previous studies utilized non-weight-bearing test positions. The purpose of this study was to develop a reliable method of testing CONC and ECC DF and PF in a weight-bearing position. One group of adults, including older men and women were tested on two occasions with a standing protocol. Another group of older and younger men and women were compared between the standing method and a supine protocol. For both positions the velocity was 30 degrees.s-1 for the CONC and ECC actions, and the range of motion was 10 degrees DF to 20 degrees PF. Reliability coefficients for peak torque (PT) were acceptable and ranged from 0.65 to 0.90. The two testing positions were significantly related (r = 0.84-0.91), but CONC PT in standing were greater than supine. Therefore, this method of testing isokinetic DF and PF in a standing position has acceptable reliability and produces results consistent with those acquired with the supine protocol. It provides a means of comparing groups and examining intervention strategies while weight-bearing.

Concentric and eccentric knee extension strength in older and younger men and women.

Decrements in isometric and concentric (Conc) muscular strength with increased age are well documented. However, little information is available on the effects of aging on eccentric (Ecc) strength, even though Ecc or lengthening muscle actions are used in most physical activities. This study examined Conc and Ecc peak torques (PT) during knee extension at 90 degrees/sec in healthy older (62 to 89 yrs) and younger (20 to 29 yrs) men and women. Conc PT decreased more with age than did Ecc (p < 0.01), for both men and women. PT values for the older men and women as a percentage of those of the younger ones were 58.3 and 46.6% for Conc, and 75.1 and 61.7% for Ecc, respectively. These age differences need to be considered during isokinetic evaluations of Conc versus Ecc strength. Other muscle groups should be investigated, and mechanisms remain to be determined.

Prolonged administration of low-dose interleukin-2 in human immunodeficiency virus-associated malignancy results in selective expansion of innate immune effectors without significant clinical toxicity.

Ten adult patients with human immunodeficiency virus (HIV)-associated malignancies (five with lymphoma and five with Kaposi's Sarcoma) were treated with a daily subcutaneous injection of interleukin-2 (IL-2) for 90 consecutive days in a phase I dose-escalation study. Seven patients had absolute CD4 counts below 200/mm3 at the time malignancy was diagnosed. Each lymphoma patient had obtained a complete or partial remission with standard chemotherapy before initiating IL-2. The daily dose of IL-2 did not change during the 90-day course of therapy. Seventeen courses of IL-2 therapy were completed at doses ranging from 0.4 x 10(6) U/m2/d to 1.2 x 10(6) U/m2/d without significant (grade III) toxicity. Two of two patients experienced grade III toxicity within 21 days of initiating IL-2 at a dose of 1.4 x 10(6) U/m2/d, but both patients subsequently completed 90 days of therapy at the maximum tolerated dose (MTD) of 1.2 x 10(6) U/m2/d. Although there were no significant increases or decreases in T-cell subsets at any dose level, there was an increase in absolute natural killer (NK) cell number at the three highest doses of IL-2 (mean percent increase 247; 95% confidence interval, 124 to 369) that was statistically significant (Wilcoxon one-sample signed rank test, P = .015). One patient developed an anti-IL-2 antibody titer that correlated with minimal NK cell expansion in vitro and in vivo. An increase in eosinophils was noted during 9 of 17 courses of IL-2 therapy without correlation to IL-2 dose, prior course of IL-2, or NK cell expansion. At the MTD, there was no consistent increase in the plasma HIV RNA level over time. Three of 10 patients had progressive disease while on study. During 50 months of IL-2 therapy, no patient was treated for an opportunistic infection. We conclude that daily low dose subcutaneous IL-2 can be self-administered safely with good compliance for prolonged periods of time to patients with HIV-associated malignancies, including those with profound immune deficiency. The majority of patients show selective expansion of innate immune effectors, ie, NK cells and/or eosinophils, in the absence of significant clinical toxicity or increased viral burden. These results suggest that low-dose IL-2 therapy should be studied further in phase II clinical trials for evidence of activity against malignancy and opportunistic infection in this patient population.

Aging of human muscle: structure, function and adaptability.

With increasing age, human skeletal muscles gradually decrease in volume, mainly due to a reduced number of motor units and muscle fibers, and a reduced size of type 2 fibers. As a result, progressive weakening and impaired mobility occur. High-resistance strength training is beneficial, even in the very old, and could possibly reverse some of the detrimental effects of age-related weakness. The importance of exercise for older people affords an excellent opportunity for the medicine community as a major source of information and promotion of physical activity for this rapidly growing segment of the population. In this review, we summarize the current knowledge of the effects of aging on the human neuromuscular system, describe some of the major underlying mechanisms of the aging atrophy and focus on the importance of strength training to improve muscle function in older people.