Michael Kalicinski

Metabolic effects of estrogen substitution in combination with targeted exercise training on the therapy of obesity in ovariectomized Wistar rats.

Postmenopausal women tend to have a higher risk in developing obesity and thus metabolic syndrome. Recently we could demonstrate that physical activity and estrogen replacement are effective strategies to prevent the development of nutritional induced obesity in an animal model. The aim of this study was to determine the combined effects of estrogen treatment and exercise training on already established obesity. Therefore ovariectomized (OVX) and sham-operated (SHAM) female Wistar rats were exposed to a high fat diet for ten months. After this induction period obese SHAM and OVX rats either remained sedentary or performed treadmill training for six weeks. In addition OVX rats were treated with 17β-Estradiol (E(2)) alone, or in combination with training. Before and after intervention effects on lipid and glucose metabolism were investigated. Training resulted in SHAM and OVX rats in a significant decrease of body weight, subcutaneous and visceral body fat, size of adipocytes and the serum levels of leptin, cholesterol, low-density lipoprotein and triglycerides. In OVX animals E(2) treatment resulted in similar effects. Often the combination of E(2) treatment and training was most effective. Analysis of the respiratory quotient indicates that SHAM animals had a better fat burning capacity than OVX rats. There was a tendency that training in SHAM animals and E(2) treatment in OVX animals could improve this capacity. Analysis of glucose metabolism revealed that obese SHAM animals had higher glucose tolerance than OVX animals. Training improved glucose tolerance in SHAM and OVX rats, E(2) treatment in OVX rats. The combination of both was most effective. Our results indicate that even after a short intervention period of six weeks E(2) treatment and exercise training improve parameters related to lipid as well as glucose metabolism and energy expenditure in a model of already established obesity. In conclusion a combination of hormone replacement therapy and exercise training could be a very effective strategy to encourage the therapy of diet-induced obesity and its metabolic consequences in postmenopausal women.

Motor Imagery: Effects of Age, Task Complexity, and Task Setting

Background/Study Context: Mental training may potentially enhance motor performance and self-efficacy in older adults. However, several studies revealed an age-related decay of motor imagery (MI), which suggests that mental training might be too challenging for older adults. Recognizing that laboratory results are often not transferable to real-life situations, the purpose of the present study was to evaluate imagery performance in the elderly with a more real-life-like approach. Methods: MI performance of 21 older (70.28 ± 4.65 years) and 19 younger adults (24.89 ± 3.16 years) was estimated by mental chronometry from the first-person perspective. Subjects were asked to walk in a supermarket scenario straight ahead (A), or with two changes of direction (B), or with two changes of direction while retrieving products (C). The three tasks were completed first in the subjects’ imagination and then in reality, with time required as the dependent measure. MI ability was also assessed by the Controllability of Motor Imagery (CMI) test, in which subjects are required to mentally assume a sequence of body postures. Results: Age-related alterations of MI were observed for walking only in Tasks B and C, and only in terms of intersubject variability, not in terms of across-subject means. This is in contrast to earlier studies that used a less realistic walking scenario and found an age-related decay even for MI means. Age-related alterations of CMI were observed as well, but they correlated little with those of walking. Conclusion: These findings suggest that MI is not a global phenomenon, as it decays in old age independently in the temporal and in the spatial domain, decays less with simple than with complex tasks, and less in an everyday-like than in a typical laboratory setting. These characteristics of MI should be taken into account when assessing its decay in old age, and when designing mental training for the elderly.

Benefits of Motor and Exercise Imagery for Older Adults

Abstract: The benefits of imagery use have been shown for athletes and neurological patients, but little is known about the benefits of motor and exercise imagery for older adults. Current research on movement-related imagery is reviewed in this narrative article, with a focus on methods for estimating the ability to use motor and exercise imagery and the extent of their use. Recent investigations of motor imagery and exercise imagery in healthy older adults are reviewed. Recommendations for integrating the two approaches in future research are made and the potential of imagery use to encourage physical activity in older adults is discussed.

The Effects of Slackline Balance Training on Postural Control in Older Adults

The present study investigated whether slackline training enhances postural control in older adults. Twenty-four participants were randomized into an intervention and a control group. The intervention group received 6 weeks of slackline training, two times per week. Pre-post measurement included the time of different standing positions on a balance platform with and without an external disturbance and the acceleration of the balance platform. Results showed significantly improved standing times during one-leg stance without external disturbance and a significantly reduced acceleration of the balance platform for the intervention group after the training period during tandem stance with and without an external disturbance. We conclude that slackline training in older adults has a positive impact on postural control and thus on the reduction of fall risk.

Human performance in a realistic instrument-control task during short-term microgravity

Previous studies have documented the detrimental effects of microgravity on human sensorimotor skills. While that work dealt with simple, laboratory-type skills, we now evaluate the effects of microgravity on a complex, realistic instrument-control skill. Twelve participants controlled a simulated power plant during the short-term microgravity intervals of parabolic flight as well as during level flight. To this end they watched multiple displays, made strategic decisions and used multiple actuators to maximize their virtual earnings from the power plant. We quantified control efficiency as the participants’ net earnings (revenue minus expenses), motor performance as hand kinematics and dynamics, and stress as cortisol level, self-assessed mood and self-assessed workload. We found that compared to normal gravity, control efficiency substantially decreased in microgravity, hand velocity slowed down, and cortisol level and perceived physical strain increased, but other stress and motor scores didn’t change. Furthermore, control efficiency was not correlated with motor and stress scores. From this we conclude that realistic instrument control was degraded in short-term microgravity. This degradation can’t be explained by the motor and/or stress indicators under study, and microgravity affected motor performance differently in our complex, realistic skill than in the simple, laboratory-type skills of earlier studies.

Naturalistic Assessment of Everyday Memory Performance Among Older Adults.

Background/Study Context: Memory performance in everyday life (EDL) and its change through aging is still unclear because laboratory results are often not transferable to real-life situations. Therefore, a naturalistic memory task was designed to investigate memory performance in older adults in a representative task design. Methods: The memory performance of 23 older (70.28 ± 4.65 years) and 20 younger adults (24.89 ± 3.16 years) was assessed by using four established tasks of short-term and working memory (Digit Simple Span, Digit Complex Span, Grid Simple Span, and Grid Complex Span) that differed in difficulty and domain (verbal vs. visual-spatial). To simulate an EDL context, a “Supermarket” was constructed within the laboratory. Results: The results showed that memory performance presents alterations in older adults. This was especially true for the “Supermarket” task, in which the younger adults showed benefits in the common environment as opposed to older adults. A factor analysis showed that the four memory laboratory tasks measured different memory processes as compared with the EDL task. Conclusion: These findings suggest that memory performance in EDL is a different construct than when it is measured in the laboratory and that memory alterations in older adults are especially pronounced in EDL tasks. Following these findings, the authors recommend an EDL approach to measure memory performance further to the well-established laboratory approaches.

Motor Imagery and Mental Training in Older Adults

Research has shown that mental training in terms of motor imagery (MI) can enhance movement skills and physical performance in younger adults. It has been used effectively in various settings for different objectives, and its application and benefits are well established for athletes. Yet, little is known about the benefits of mental training and MI for healthy older adults. In this chapter, we introduce the mechanisms underlying MI and provide a brief overview of MI research and mental training, focusing on healthy older adults. Finally, we describe the procedures and results of a recently conducted mental training intervention study that aimed at improving postural control in older adults.