This study determined the decline in oxidative capacity per volume of human vastus lateralis muscle between nine adult (mean age 38.8 years) and 40 elderly (mean age 68.8 years) human subjects (age range 25‐80 years). We based our oxidative capacity estimates on the kinetics of changes in creatine phosphate content ([PCr]) during recovery from exercise as measured by 31P magnetic resonance (MR) spectroscopy. A matched muscle biopsy sample permitted determination of mitochondrial volume density and the contribution of the loss of mitochondrial content to the decline in oxidative capacity with age. The maximal oxidative phosphorylation rate or oxidative capacity was estimated from the PCr recovery rate constant (kPCr) and the [PCr] in accordance with a simple electrical circuit model of mitochondrial respiratory control. Oxidative capacity was 50 % lower in the elderly vs. the adult group (0.61 ± 0.04 vs. 1.16 ± 0.147 mM ATP s−1). Mitochondrial volume density was significantly lower in elderly compared with adult muscle (2.9 ± 0.15 vs. 3.6 ± 0.11 %). In addition, the oxidative capacity per mitochondrial volume (0.22 ± 0.042 vs. 0.32 ± 0.015 mM ATP (s %)−1) was reduced in elderly vs. adult subjects. This study showed that elderly subjects had nearly 50 % lower oxidative capacity per volume of muscle than adult subjects. The cellular basis of this drop was a reduction in mitochondrial content, as well as a lower oxidative capacity of the mitochondria with age.

Context Uncertainties exist about the rates, predictors and outcomes of major depressive disorder (MDD) among people with traumatic brain injury (TBI). Objectives To describe MDD related rates, predictors, outcomes and treatment during the first year after TBI Design Cohort from 6/2001–3/2005 followed by structured telephone interviews at months 1–6, 8, 10, and 12 (data collection ending 2/2006). Setting Harborview Medical Center, a Level I trauma center in Seattle, WA Participants 559 consecutively hospitalized adults with complicated mild to severe TBI Main Outcome Measures The Patient Health Questionnaire (PHQ) depression and anxiety modules were administered at each assessment and the European Quality of Life measure (EQ-5D) was given at 12 months. Results 53% met criteria for MDD at least once in the follow-up period. Point prevalences ranged between 31% at one month and 21% at six months. In a multivariate model, increased risk of MDD after TBI was associated with MDD at the time of injury (risk ratio [RR], 1.62; 95% confidence interval [CI], 1.37–1.91), history of MDD prior to injury (but not at the time of injury) (RR, 1.54; 95% CI, 1.31–1.82), age (RR, 0.61; 95% CI, 0.44–0.83 for 60+ years vs. 18–29 years) and lifetime alcohol dependence (RR, 1.34; 95% CI, 1.14–1.57). Those with MDD were more likely to report co-morbid anxiety disorders after TBI than those without MDD (60% versus 7%; RR, 8.77; 95% CI, 5.56–13.83). Only 44% of those with MDD received antidepressants or counseling. After adjusting for predictors of MDD, persons with MDD reported lower quality of life at one year, compared to the nondepressed group. Conclusions Among a cohort of patients hospitalized for TBI, 53% met criteria for MDD during the first year after TBI. MDD was associated with prior history of MDD and was an independent predictor of poorer health-related quality of life.

Exercise may have beneficial effects on fall rates and health care use in some subgroups of older adults. In community-living adults with mainly mild impairments in gait, balance, and physical health status, short-term exercise may not have a restorative effect on these impairments.

The PHQ-9 is a valid and reliable screening tool for detecting MDD in persons with TBI.

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SUMMARY The activation times for trunk and leg muscles were examined in normal and left hemiplegic subjects who raised their right arms at different velocities in self-paced or reaction time conditions. Activity in these postural muscles preceded arm displacement, and they were activated in a similar sequence during all types of rapid movements. The presence and sequencing of associated postural adjustments were more variable during slow movements.Movement of an extremity, such as the arm, causes dynamic forces to be applied to the trunk, and these will act on the multisegmented kinematic chain between the shoulder and the base of support. The forces acting between a moving arm and the trunk are complex, but they must include linear centrifugal forces, inertial reactive forces, and torsional movements. In addition to the inertial reactions, the movement may cause a static displacement of body mass with respect to the support base, such that a postural adjustment will be necessary to maintain stability by keeping the center of mass over the vertical projection of the supporting base. If stability is to be maintained during voluntary movement, it is likely that neurally controlled postural adjustment or stabilisation must be produced by muscular activity, as a supplement to reactive forces provided by structures such as the ligaments. The required muscular activity could be controlled in two ways: (1) it could be centrally programmed, as part of the total motor act, or (2) it could be initiated reflexly by the consequences of the muscular contractions and/or the movement.Belen'kii et al' recorded the electromyographic (EMG) activity of the anterior deltoid and several muscles in the trunk and lower extremities in standing normal individuals who rapidly raised their arm

Humans produce less muscle force (F) as they age. However, the relationship between decreased force and muscle cross-sectional area (CSA) in older humans is not well documented. We examined changes in F and CSA to determine the relative contributions of muscle atrophy and specific force (F/CSA) to declining force production in aging humans. The proportions of myosin heavy chain (MHC) isoforms were characterized to assess whether this was related to changes in specific force with age. We measured the peak force of isokinetic knee extension in 57 males and females aged 23-80 years, and used magnetic resonance imaging to determine the contractile area of the quadriceps muscle. Analysis of MHC isoforms taken from biopsies of the vastus lateralis muscle showed no relation to specific force. F, CSA, and F/CSA decreased with age. Smaller CSA accounted for only about half of the 39% drop in force that occurred between ages 65-80 years. Specific force dropped about 1.5% per year in this age range, for a total decrease of 21%. Thus, quantitative changes in muscle (atrophy) are not sufficient to explain the strength loss associated with aging.

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