Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

The world’s population is aging rapidly, as both life expectancy and the proportion of older people are increasing. This aging of the population is an indicator of improved health conditions and should be considered as a success story. However, it is also one of the main challenges that the world is facing because there is a growing need to prevent age-associated declines and diseases such as cardiovascular disease, diabetes, dementia, and osteoporosis. Physicalnbsp;(PA) has been identified as a major public health priority because it can help to prevent, or even reverse age-associated declines and losses of many physical and psychological variables.The present doctoral thesis, entitled ‘Objective assessment and promotion of PA in older adults living in residential care facilities’ focuses on three interrelated aims: assessment (CHAPTER 1), screening (CHAPTER 2), and intervention (CHAPTER 3). The first aim was to investigate the validity of two motion sensors in institutionalized older adults (Paper 1 and Paper 2). Accurate quantification of both PA and sedentary behavior isnbsp;for screening, goal setting, and program evaluation. The second aim was to examine the link between muscle strength and functional performance, and to identify functionally relevant cut-off values for knee extension strength in older adults (Paper 3). It is important to determine physical characteristics related to functional deterioration, as this will eventually lead to a loss of independence and institutionalization, and an increase in healthcare costs. Finally, thenbsp;aim was to examine the short- andnbsp;effects on PA, functional performance and muscle strength of a 10-week cycle ergometer intervention in assisted living facilities (Paper 4). PA promotion in older adults is important because a large proportion of the older population is not regularly involved in PA.Paper 1 examined the accuracy of a hip-worn and ankle-worn piezoelectric pedometer and the multisensornbsp;Mini (SWMini) in measuring steps during daily life activities in nursing home residents (N=68; mean age=86 years). The results revealed that the multisensor and hip- and ankle-worn pedometer significantly underestimated step counts, although measurement accuracy was higher when the pedometer was worn at the ankle. Moreover, pedometer accuracy improved as walking speed increased. The ankle-worn piezoelectric pedometer proved to be acceptably accurate for quantifying steps at walking speeds of ≥2.35 km/h. Next to step counts, energy expenditure (EE) is a common outcome when assessing PA in daily life. Therefore, the purpose of Paper 2 was to examine the validity of the SWMini to measure EE during rest and during the performance of daily life activities in a sample of nursing home residents (N=60; mean age=86 years). The results showed that the SWMini can be applied for describing and quantifying sitting time in institutionalized older adults because significant increases between sitting periods and daily life activity tasks were found. In addition, analyses revealed that the SWMini demonstrated good agreement with indirect calorimetry, although the device underestimated EE. Age was determined as a key factor of accuracy, suggesting that accurate age- and activity-specific algorithms should be developed.nbsp;second chapter of this doctoral thesis examined whether knee extension and handgrip strength, measured using two field tests, are good predictors ofnbsp;performance among older adults (nbsp;years). In total, 770 community-dwelling older adults, 104 older adults living in assisted living facilities and 73 nursing home residents were included in Paper 3 to cover a broad range of strength performance and functionality levels. Results revealed that both handgrip and knee extension are important predictors of functional performance in older adults. In assisted living facilities only, knee extension strength proved to be a better predictor of functional performance than handgrip strength. Early identification of persons with muscle weakness might create opportunities for developing and implementing strategies to counteract disability. Specific cut-off values for functionally relevant muscle strength for men and women respectively were set at 0.40 and 0.31 kg per kg body weight (BW) for lower body strength and at 0.43 and 0.31 kg per kg BW for upper body strength. These cut-off values should be used in clinical practice to detect and double check older adults at risk for muscle weakness, using simple field tests.The results obtained in Paper 3 contributed to the development of a PA intervention in Paper 4. In this paper, ergometer cycling was used for the promotion of PA among residents living in an assisted living facility (N=95, mean age=82 years). Ergometer cycling trains the cardio-respiratory system as well as lower body muscles. The purpose of this last paper was to evaluate the short- and long-term effectiveness of an ergometer cycling intervention, comparing 2 coaching procedures: (1) structured fitness coaching (STRUC) with permanent assistance, consisting of three weekly sessions on a cycle ergometer, and (2) autonomy-supportive coaching (AUT) based on the Self-Determination Theory, consisting of an individualized cycle ergometer program with minimal coaching contact. Especially the autonomy-component considerably differed between both intervention groups as participants in AUT had to complete the program on their own, without supervision ofnbsp;coach. The effects on adherence rate, PA, functionality and muscle strength were assessed at baseline, post-intervention (10 weeks after pre) and at follow-up (24 weeks after post). Results showed that minimal contact with a coach is sufficient to promote ergometer cycling in older adults, but training volumes are higher in bothnbsp;short- and long-term when training is strictly supervised. Contrary to our hypotheses, stimulating autonomy in this age group did not result in higher long-term adherence rates. Self-reported moderate intensity PA increased from pre tonbsp;in both intervention groups in comparison with the control group. However, only AUT showed short-term gains in daily EE. At last, older adults who exercised more frequently on the cycle ergometer showed better short-term results on functionality and muscle strength, even though improvements were small.The present doctoral thesis offers important information regarding screening of older adults at risk for functional impairment, and regarding objective assessment and promotion of PA in older adults living in residential care facilities. Researchers and practitioners can use this information for future PA recommendations and PA interventions in the old and old-old.

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

To obtain more in-depth insights in biomechanical factors determining performance during sprint running, spatio-temporal parameters were investigated. Special designed field tests, laboratory-like conditions and advanced biomechanical analysis techniques were used. This dissertation documents the development of technical skills as well as the performance determining factors throughout the different phases of sprint running; across sexes and across different age categories. The specific aims of this dissertation are five-fold:1. To identify the contribution of step length and step rate to performance during the different phases of sprint running in high level male and female sprinters.2. To identify the technical skills underlying an efficient transition from start action into sprint running.3. To differentiate the technical skills of adult and adolescent sprinters during the transition from start action into sprint running.4. To document the change in technical skills underlying the transition from start action into sprint running in young sprinters in a longitudinal follow-up.5. To identify the contribution of individual lower limb joints and muscles to forward and upward acceleration during the first two stances after block clearance.The first study aims to document the role of step length and step rate in sprint running performance in high-level athletes throughout the three phases of the sprint run, i.e. initial acceleration, secondary acceleration and sprinting at maximal speed. Previous studies remained inconclusive on how step rate and step length interact to determine sprint performance during the different phases of the sprint run. It is furthermore not known which strategy is most optimal for developing and maintaining running speed: should one emphasize step length by maximizing the forward impulse, or is it better to emphasize step rate by diminishing contact time and inertia. Changes in both step length and step frequency therefore need to be considered simultaneously to describe how running speed and therefore performance is achieved. Ten high-level male and female sprinters ran two all-out 60 meter sprints. During the three phases of sprinting, step rate remained constant and did not differ significantly between males and females. The data analysis indicates that step characteristics interact differently in males and females across phases. Men do not take full advantage of their higher explosive strength to develop step length and speed during initial acceleration. However males outscored females clearly during secondary acceleration as they were capable to develop higher step lengths. At maximal speed, males and females optimize the balance between step rate and step length and a high negative correlation is found in both sexes. From this study and from the findings published in literature, we conclude that athletes need specific technical skills to deal with the specific biomechanical demands and to successfully conclude the transition from block clearance into sprint running. The second study characterizes the technical specificities during the transition from block clearance into sprint running. Twenty-one well-trained sprinters executed an explosive start action. By means of an opto-electronic motion analysis and two Kistler force plates, the 3D marker trajectories and ground reaction forces were collected. Subsequently, 3D kinematics, joint kinetics and power were calculated using Opensim and afterwards time normalized to 100% from the first action after gunshot until the end of second stance after block clearance. This study shows that during the first stance, power generation at the knee plays a significant role in obtaining an effective transition, representing 31% of power generation in the lower limb, in the absence of preceding power absorption. Furthermore, the sprinter actively searches a more forward leaning position to maximize horizontal velocity generation. From the second stance onwards sprinting success involves high hip and ankle action, the above-mentioned three characteristics are specific skills to successfully conclude the transition from start block into sprint running.The third study relates sprinting performance to the specific technical skills during the first two stances of sprint running in three age groups of high-level well-trained sprinters. Since literature shows that explosive strength of the lower limbs is a performance determining factor in predicting ten meter sprint time and since younger athletes have not yet developed their full potential, it is to be expected that younger sprinters apply different strategies during stance to run transition, in order to compensate their lack of strength. Eleven under sixteen (U16), eighteen under eighteen (U18) promising sprinters and fourteen well-trained adult sprinters executed an explosive start action, similarly as the athletes of study two This study shows that younger athletes lack the specific technical skills observed in adult athletes to successfully initiate the transfer from start action to sprint running. In younger athletes, power generation of hip and ankle joint are dominant. Adult athletes rely on higher knee power generation and more hip abduction during the first stance to induce larger impulses, longer step length and therefore higher velocity and acceleration.To better understand the development of technical skills in a single athlete, the fourth study included seven sprinters, who were followed over a 2-year period. The conclusion of such a longitudinal study may well differ from the generalized differences observed in a cross-sectional design. We conclude that the improvement of sprint start performance in young athletes can be related to specific positional changes rather than increased power generation of the lower limb joints. An increased hip extension resulting in a more erected position and therefore affecting the lengthening of the leg provides an increase in rotational energy at the beginning of stance. The increase of leg extension velocity due to a larger ROM of the lower limb and a more anterior positioning of the COM results in an increase of translational energy at the end of stance. As a result, sprinters were able to attain higher velocities at the end of first stance. These descriptive studies are unable to relate the contribution of hip, knee or ankle to forward and/or upward acceleration of the body center of mass. The fifth study therefore aims to relate the contribution of lower limb joint moments and individual muscle forces to the specific biomechanical demands and more specific the body center of mass (COM) vertical and horizontal acceleration during the initial two steps of sprint running. Sprint start performance of seven well-trained sprinters was measured and subject-specific torque and muscle driven simulations were conducted to quantify the contributions of the individual joints to forward and upward acceleration of the body COM. The ankle joint is the major contributor to propulsion and body rise during the first two stances. This contribution even increased from the first to the second stance. The contribution of the hip and knee joint depends highly on the position of the athlete: During the first stance the knee contributes primarily to body rise, to lift the athlete from the bended starting position. The hip on the other hand contributes to both propulsion and body rise.Apart from providing fundamental scientific insights in the biomechanics of sprint running, the findings of these studies also have important implications for sprint coaches. Coaches first of all need to be aware of the multidimensional structure of sprint performance and the corresponding performance determining factors when designing a training program. Optimization of performance requires investing in specific technical skill training to attain an efficient running technique, relevant for the specific phase of sprint running. Furthermore, strength training additionally remains an essential part of the athletes’ preparation