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Five times sit-to-stand (STS) test is commonly used as a clinical assessment of lower-extremity functional ability, but its association with free-living performance has not been studied. Therefore, we investigated the association between laboratory-based STS capacity and free-living STS performance using accelerometry. The results were stratified according to age and functional ability groups. Methods: This cross-sectional study included 497 participants (63% women) 60-90 yr old from three independent studies. A thigh-worn triaxial accelerometer was used to estimate angular velocity in maximal laboratory-based STS capacity and in free-living STS transitions over 3-7 d of continuous monitoring. Functional ability was assessed with short physical performance battery. Results: Laboratory-based STS capacity was moderately associated with the free-living mean and maximal STS performance (r = 0.52-0.65, P < 0.01). Angular velocity was lower in older compared with younger and in low- versus high-functioning groups, in both capacity and free-living STS variables (all P < 0.05). Overall, angular velocity was higher in capacity compared with free-living STS performance. The STS reserve (test capacity - free-living maximal performance) was larger in younger and in high-functioning groups compared with older and low-functioning groups (all P < 0.05). Conclusions: Laboratory-based STS capacity and free-living performance were found to be associated. However, capacity and performance are not interchangeable but rather provide complementary information. Older and low-functioning individuals seemed to perform free-living STS movements at a higher percentage of their maximal capacity compared with younger and high-functioning individuals. Therefore, we postulate that low capacity may limit free-living performance. [ABSTRACT FROM AUTHOR]

The objectives of this study were (1) to evaluate the long-term effects of a lifestyle physical activity intervention (n = 60) and a structured exercise intervention (n = 60) on physical self-perceptions and self-esteem in older adults compared with a control group (n = 66), and (2) to test the longitudinal fit of the exercise and self-esteem model (EXSEM). Immediately after the 11-month interventions, the lifestyle group showed significant improvements in self-perceived physical condition, sport competence, body attractiveness, and physical self-worth. In the structured group, significant effects were found on physical condition and sport competence. One year later, the lifestyle program had significant effects on body attractiveness and global self-esteem, while the structured group showed significant improvements in physical condition, sport competence, and body attractiveness. Path analyses revealed a good fit for the EXSEM across the 2-year period. [ABSTRACT FROM AUTHOR]

Peak power (pP) declines during aging, resulting in reduced functional performance. However, the rate of power development (RPD) takes into account the short response times available during many functional tasks and may therefore add valuable information to functional declines. This study examined the age-related effects on pP and RPD of the knee-extensors across different loads and how these are related to functional performance. 36 young (♂21, ♀15, age = 22 ± 2 years) and 56 older adults (♂26, ♀30, age = 68 ± 5 years) performed four maximal isotonic contractions against three loads (40, 20 and 60% of maximal isometric strength) on a Biodex System 3 dynamometer. pP was calculated as the highest value and RPD as the linear slope of the power-time curve. Functional performance in the older group was tested by 7.5-meter fast walk, timed up-and-go and stair climbing. pP and RPD were higher in young compared to old and this was more pronounced with lower loads. Age-related differences in RPD (range from 37 to 44% across loads) were higher than in pP (24–37%). Both pP and RPD showed a positive correlation with functional performance (r: 0.59–0.64). To conclude, percent differences in RPD exceed differences in pP between young and old. This emphasizes the inability to generate power rapidly at older age and underlines the importance of time-dependent measures to detect age-related changes in muscle function. [ABSTRACT FROM AUTHOR]

The aim of this study was to relate the contribution of lower limb joint moments and individual muscle forces to the body centre of mass (COM) vertical and horizontal acceleration during the initial two steps of sprint running. Start performance of seven well-trained sprinters was recorded using an optoelectronic motion analysis system and two force plates. Participant-specific torque-driven and muscle-driven simulations were conducted in OpenSim to quantify, respectively, the contributions of the individual joints and muscles to body propulsion and lift. The ankle is the major contributor to both actions during the first two stances, with an even larger contribution in the second compared to the first stance. Biarticular gastrocnemius is the main muscle contributor to propulsion in the second stance. The contribution of the hip and knee depends highly on the position of the athlete: During the first stance, where the athlete runs in a forward bending position, the knee contributes primarily to body lift and the hip contributes to propulsion and body lift. In conclusion, a small increase in ankle power generation seems to affect the body COM acceleration, whereas increases in hip and knee power generation tend to affect acceleration less. [ABSTRACT FROM PUBLISHER]

Background The first purpose was to examine whether knee extension strength is a better predictor of functional performance than handgrip strength among older adults (≥60 years). The second purpose was to identify functionally relevant cut-off values for muscle strength. Methods 770 community-dwelling older adults, 104 older adults living in assisted living facilities and 73 nursing home residents were included. Static strength, expressed in kg/kg body weight (BW), was measured using two field tests: handgrip (GRIP/BW) and knee extension (KNEE/BW) test. Functional performance was assessed with 6-Minute Walk Distance (6MWD, N = 947) and modified Physical Performance Test (mPPT, N = 152). Results Both GRIP/BW and KNEE/BW were positively correlated with functional performance in all settings ( p < 0.05). In the community and nursing homes, both strength variables equally contributed to functional performance. In assisted living facilities, KNEE/BW ( R 2 6MWD = 0.39 and R 2 mPPT = 0.35) was clearly a better predictor of functional performance than GRIP/BW ( R 2 6MWD = 0.15 and R 2 mPPT = 0.12). GRIP/BW had no added value to KNEE/BW in order to explain the variance in functional performance. Functionally relevant cut-off values for static strength, for men and women respectively, were set at 0.40 and 0.31 for KNEE/BW and at 0.43 and 0.31 for GRIP/BW. Conclusions Handgrip and knee extension strength are both important predictors of functional performance in older adults. In assisted living facilities only, knee extension strength was clearly more predictive than handgrip strength. Both cut-off values appear to be highly sensitive to screen for functionally relevant muscle weakness in older adults. [ABSTRACT FROM AUTHOR]

Muscle adaptations can be induced by high-resistance exercise. Despite being potentially more suitable for older adults, low-resistance exercise protocols have been less investigated. We compared the effects of high- and low-resistance training on muscle volume, muscle strength, and force–velocity characteristics. Fifty-six older adults were randomly assigned to 12weeks of leg press and leg extension training at either HIGH (2×10–15 repetitions at 80% of one repetition maximum (1RM)), LOW (1×80–100 repetitions at 20% of 1RM), or LOW+ (1×60 repetitions at 20% of 1RM, followed by 1×10–20 repetitions at 40% of 1RM). All protocols ended with muscle failure. Leg press and leg extension of 1RM were measured at baseline and post intervention and before the first training session in weeks 5 and 9. At baseline and post intervention, muscle volume (MV) was measured by CT-scan. A Biodex dynamometer evaluated knee extensor static peak torque in different knee angles (PTstat90°, PTstat120°, PTstat150°), dynamic peak torque at different speeds (PTdyn60°s −1, PTdyn180°s −1, PTdyn240°s −1), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat90°. HIGH and LOW+ resulted in greater improvements in 1RM strength than LOW (p<0.05). These differences were already apparent after week 5. Similar gains were found between groups in MV, PTstat, PTdyn60°s −1, and PTdyn180°s −1. No changes were reported in speed of movement. HIGH tended to improve PTdyn240°s −1 more than LOW or LOW+ (p=0.064). In conclusion, high- and low-resistance exercises ending with muscle failure may be similarly effective for hypertrophy. High-resistance training led to a higher increase in 1RM strength than low-resistance training (20% of 1RM), but this difference disappeared when using a mixed low-resistance protocol in which the resistance was intensified within a single exercise set (40% of 1RM). Our findings support the need for more research on low-resistance programs in older age, in particular long-term training studies and studies focusing on residual effects after training cessation. [ABSTRACT FROM AUTHOR]

This study examined the long-term and mediation effects of a need-supportive coaching programme on physical activity. Sedentary employees (n = 92) of the university of Leuven received 4 months of physical activity coaching, based on the self-determination theory, by coaches with a bachelor's degree in kinesiology who are specializing in health-related physical activity (n = 30). The programme consisted of a limited number of individual contact moments (i.e. an intake session, three follow-up contacts and an out-take session), either face-to-face, by phone or by e-mail. Self-reported physical activity, social support, self-efficacy and autonomous motivation were assessed in the coaching group (n = 92) and a control group (n = 34) at three moments: before the intervention (i.e. pre-test), after the intervention (i.e. post-test) and 1 year after pre-test measurements (i.e. follow-up test). Results revealed significant 3 (time) × 2 (groups) interaction effects on strenuous and total physical activity. Moreover, whereas the control group remained stable from pre- to post-test, the coaching group increased significantly in moderate, strenuous and total physical activity. Additionally, the coaching group increased significantly in mild, moderate, strenuous and total physical activity from pre- to follow-up tests, whereas the control group did not change. Bootstrapping analyses indicated that self-efficacy and autonomous motivation significantly mediated the intervention effect on physical activity from pre- to post-test, while social support significantly mediated the long-term effect. This study provides evidence for the long-term effectiveness of a need-supportive physical activity programme that might be efficient at the community level. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the physical characteristics and somatotype of junior and senior athletes in relation to sprint start and acceleration performance. Nineteen female junior, 23 male junior, 9 female senior, and 16 male senior sprint athletes performed three maximal 20-m sprints. The starting blocks were instrumented to measure forward propulsion forces. Running velocity was measured by a laser positioned behind the athlete at 1 m height. Anthropometric measures were used to calculate somatotype and skeletal muscle mass. Body composition was estimated by underwater weighing densitometry. Junior and senior athletes were of similar height in both sexes. Male seniors were heavier, had larger limb circumferences, and a higher skeletal muscle mass than male juniors. Only the limb circumferences of the female seniors were larger than those of the female juniors. Female juniors were balanced ectomorphs, while female seniors were situated centrally on the somatochart (2.7–2.2–3.9 vs. 2.6–3.1–3.1; P=0.772, 0.047, and 0.066 respectively). Male juniors were mesomorphic ectomorphs, while male seniors were ectomorphic mesomorphs (1.8–3.3–3.6 vs. 1.6–4.2–2.8; P=0.148, 0.002, and 0.002 respectively). All sprint starts were similar for the junior and senior athletes of both sexes. Senior athletes accelerated more than the junior athletes, which resulted in higher running velocities after 5 m (senior vs. junior: females, 5.51±0.32 vs. 6.01±0.27 m · s–1, P=0.001; males, 5.85±0.38 vs. 6.13±0.44 m · s–1, P=0.043). The greater muscularity of senior compared with junior athletes did not result in better sprint start dynamics, but they did accelerate more and ran faster. These results show that late-adolescent boys in particular are still developing their muscularity. The technical complexity of the sprint start and the negative influence of a higher body mass may partly explain the comparable sprint start dynamics of the junior and senior athletes. We suggest that strength training should be combined with sufficient attention to technical skills to allow a positive transfer. [ABSTRACT FROM AUTHOR]

OBJECTIVES: To evaluate the long-term effects of a lifestyle intervention and a structured exercise intervention on physical fitness and cardiovascular risk factors in older adults. DESIGN: Controlled trial with randomization between the intervention groups. SETTING: Belgium, Vlaams-Brabant. PARTICIPANTS: One hundred eighty-six sedentary but healthy men and women aged 60 to 83. INTERVENTIONS: Participants in the lifestyle intervention were stimulated to integrate physical activity into their daily routines and received an individualized home-based program supported by telephone calls. The structured intervention consisted of three weekly supervised sessions in a fitness center. Both interventions lasted 11 months and focused on endurance, strength, flexibility, and postural and balance exercises. MEASUREMENTS: Cardiorespiratory fitness, muscular strength, functional performance, blood pressure, and body composition were measured before (pretest), at the end (11 months, posttest), and 1 year after the end (23 months, follow-up) of the interventions. RESULTS: The results from pretest to posttest have already been published. The current study analyzed the results from posttest to follow-up. There was a decrease in cardiorespiratory fitness, muscular fitness, and functional performance from posttest to follow-up in the structured intervention group but not in the control group or the lifestyle intervention group. At 23 months, participants in both groups still showed improvements in cardiorespiratory fitness. In addition, the structured group showed long-term improvements in muscular fitness, whereas the lifestyle group showed long-term improvements in functional performance. No long-term effects were found for blood pressure or body composition. CONCLUSION: These results highlight the potential of a structured fitness center-based intervention and a home-based lifestyle intervention in the battle against inactivity in older adults. Lifestyle programs are especially valuable because they require fewer resources and less time from health institutions and health practitioners. [ABSTRACT FROM AUTHOR]

Abstract: Falls in the elderly consitute a growing public health problem. This randomized controlled trial investigated the potential benefit of 6 months of whole body vibration (WBV) training and/or vitamin D supplementation on balance, functionality and estimated fall risk in institutionalized elderly women. A total of 113 women (mean age: 79.6) were randomly assigned to either a WBV or a no-training group, receiving either a conventional dose (880IU/d) or a high dose (1600IU/d) of vitamin D3. The WBV group performed exercises on a vibration platform 3×/week. Balance was evaluated by computerized posturography. Functionality was assessed by 10m walk test, Timed up and Go (TUG) performance and endurance capacity (Shuttle Walk). Fall risk was determined with the Physiological Profile Assessment. Performance on the 10m walk test and on TUG improved over time in all groups. For none of the parameters, high-dose vitamin D resulted in a better performance than conventional dosing. The improvements in the WBV group in endurance capacity, walking at preferred speed, and TUG were significantly larger than the changes with supplementation alone. No additional benefit of WBV training could be detected on fall risk and postural control, although sway velocity and maximal isometric knee extension strength improved only in the WBV group. This trial showed that a high-dose vitamin D supplementation is not more efficient than conventional dosing in improving functionality in institutionalized elderly. WBV training on top of vitamin D supplementation provided an added benefit with regard to walking, TUG performance, and endurance capacity. [Copyright &y& Elsevier]

Background: whole body vibration (WBV) training appears to be an efficient alternative for conventional resistance training in older individuals. So far, no data exist about the vibratory effect on cardiorespiratory fitness. Objectives: this randomised controlled trial assessed the effects of 1-year WBV training on cardiorespiratory fitness and muscle strength in community-dwelling adults over the age of 60. Methods: a total of 220 adults (mean age 67.1 years) were randomly assigned to a WBV group, fitness group or control group. The WBV group exercised on a vibration platform, and the fitness group performed cardiovascular, resistance, balance and stretching exercises. The control group did not participate in any training. Heart rate was measured during a single WBV session. Peak oxygen uptake (VO2peak) and time-to-peak exercise (TPE) were measured during progressive bicycle ergometry. Muscle strength was assessed by a dynamometer. Results: heart rate increased significantly during WBV training. After 1 year, VO2peak, TPE and muscle strength increased significantly in the WBV and fitness groups. Both training groups improved similarly in VO2peak and muscle strength. The fitness group improved significantly more in TPE than the WBV group. Conclusion: WBV training in community-dwelling elderly appears to be efficient to improve cardiorespiratory fitness and muscle strength. [ABSTRACT FROM AUTHOR]

Background. This randomized controlled study investigated the effects of 1-year whole-body vibration (WBV) training on isometric and explosive muscle strength and muscle mass in community-dwelling men older than 60 years. Methods. Muscle characteristics of the WBV group (n = 31, 67.3 ± (1.7 years) were compared with those of a fitness (FIT) group (n = 30, 67.4 ± 0.8 years) and a control (CON) group (n = 36, 68.6 ± (1.9 years). Isometric strength of the knee extensors was measured using an isokinetic dynamometer, explosive muscle strength was assessed using a counter movement jump, and muscle mass of the upper leg was determined by computed tomography. Results. Isometric muscle strength, explosive muscle strength, and muscle mass increased significantly in the WBV group (9.8%. 1(1.9%, and 3.4%, respectively) and in the FIT group (13.1%, 9.8%, and 3.8%, respectively) with the training effects not significantly different between the groups. No significant changes in any parameter were found in the CON group. Conclusion. WBV training is as efficient as a fitness program to increase isometric and explosive knee extension strength and muscle mass of the upper leg in community-dwelling older men. These findings suggest that WBV training has potential to prevent or reverse the age-related loss in skeletal muscle mass, referred to as sarcopenia. [ABSTRACT FROM AUTHOR]

Background. Although health-related benefits of fitness training in older men are well established, it is not clear yet which mode and intensity of a exercise program is most effective. This study addresses whether the combination of endurance (ED) and resistance training in older men have supplementary health-related benefits in addition to profits attained through endurance training alone. Additionally, effects of moderate- and low-intensity resistance training are compared.Methods. Men, 55–75 years of age, were randomly assigned to a control group (N = 13) or one of three exercise groups (20 weeks, two to three times per week): endurance plus moderate resistance (MR) training (N = 22), endurance plus low resistance (LR) training (N = 22) and endurance training only (N = 22). Cardiovascular (CV) risk factors, muscular fitness and postural control were assessed before and after training.Results. All exercise groups revealed significant (P < 0.05) improvements in resting heart rate, work capacity and recovery, waist girth, insulin response and knee-extensor strength with no differences among groups. Body composition, resting metabolic rate (RMR), VO2peak and postural control did not change in exercise groups.Conclusion. In older men, a fitness program consisting of 20 weeks endurance training combined with resistance training is equally effective as endurance training alone. Moderate vs. low resistance training added to endurance training yields similar health-related benefits. [Copyright &y& Elsevier]

To investigate the effects of 24 weeks of whole-body-vibration (WBV) training on knee-extension strength and speed of movement and on counter-movement jump performance in older women. A randomized, controlled trial. Exercise Physiology and Biomechanics Laboratory, Leuven, Belgium Eighty-nine postmenopausal women, off hormone replacement therapy, aged 58 to 74, were randomly assigned to a WBV group (n=30), a resistance-training group (RES, n=30), or a control group (n=29). The WBV group and the RES group trained three times a week for 24 weeks. The WBV group performed unloaded static and dynamic knee-extensor exercises on a vibration platform, which provokes reflexive muscle activity. The RES group trained knee-extensors by performing dynamic leg-press and leg-extension exercises increasing from low (20 repetitions maximum (RM)) to high (8RM) resistance. The control group did not participate in any training. Pre-, mid- (12 weeks), and post- (24 weeks) isometric strength and dynamic strength of knee extensors were measured using a motor-driven dynamometer. Speed of movement of knee extension was assessed using an external resistance equivalent to 1%, 20%, 40%, and 60% of isometric maximum. Counter-movement jump performance was determined using a contact mat. Isometric and dynamic knee extensor strength increased significantly ( P<.001) in the WBV group (mean±standard error 15.0±2.1% and 16.1±3.1%, respectively) and the RES group (18.4±2.8% and 13.9±2.7%, respectively) after 24 weeks of training, with the training effects not significantly different between the groups ( P=.558). Speed of movement of knee extension significantly increased at low resistance (1% or 20% of isometric maximum) in the WBV group only (7.4±1.8% and 6.3±2.0%, respectively) after 24 weeks of training, with no significant differences in training effect between the WBV and the RES groups ( P=.391; P=.142). Counter-movement jump height enhanced significantly ( P<.001) in the WBV group (19.4±2.8%) and the RES group (12.9±2.9%) after 24 weeks of training. Most of the gain in knee-extension strength and speed of movement and in counter-movement jump performance had been realized after 12 weeks of training. WBV is a suitable training method and is as efficient as conventional RES training to improve knee-extension strength and speed of movement and counter-movement jump performance in older women. As previously shown in young women, it is suggested that the strength gain in older women is mainly due to the vibration stimulus and not only to the unloaded exercises performed on the WBV platform. [ABSTRACT FROM AUTHOR]

Purpose: Habitual strength and power-demanding activities of daily life may support the maintenance of adequate lower extremity functioning with aging, but this has been sparingly explored. Hence, we examined whether the characteristics of free-living sit-to-stand (STS) transitions predict a decline in lower extremity functioning over a 4-yr follow-up. Methods: A total of 340 community-dwelling older adults (60% women; age 75, 80, or 85 yr) participated in this prospective cohort study. At baseline, a thigh-worn accelerometer was used continuously (3-7 d) to monitor the number and intensity of free-living STS transitions. A decline in lower extremity functioning was defined as a drop of ≥2 points in the Short Physical Performance Battery (SPPB) from baseline to follow-up. Maximal isometric knee extension strength was measured in the laboratory. Results: Eighty-five participants (75%women) declined in SPPB over 4 yr. After adjusting for age, sex, and baseline SPPB points, higher free-living peak STS angular velocity (odds ratio (OR), 0.70; 95% confidence interval (CI), 0.52-0.92, per 20°⋅s-1 increase) protected against a future decline. When adjusting the model for maximal isometric knee extension strength, the statistical significance was attenuated (OR = 0.72; 95% CI = 0.54-0.96, per 20°⋅s-1 increase). Conclusions: Performing STS transitions at higher velocities in the free-living environment can prevent a future decline in lower extremity function. This indicates that changes in daily STS behavior may be useful in the early identification of functional loss. Free-living peak STS angular velocity may be a factor underlying the longitudinal association of lower extremity strength and performance. [ABSTRACT FROM AUTHOR]

A good stair‐climbing (SC) ability is crucial for independent living in older adults. A simple formula that estimates the mean power needed to ascend a flight of stairs in a predetermined time (i.e., total ascent duration) is easy to implement in practice, but lacks information on actual power values generated per step. The latter is possible with body‐fixed sensors. This study aimed at comparing both methodologies and investigating their sensitivity to detect age‐related differences. 318 participants (162 ♀; age 19–85 years) were tested on a 6‐step staircase and two methodologies were used to estimate mean SC power: (1) a body‐fixed sensor with automated detection of power production per step, and (2) a mathematic equation based on timed ascent duration, body mass and stair height. SC power was 210.4 W lower with formula compared to sensor, lower in women versus men and in older versus young adults (p < 0.001). The difference in SC power between sensor and formula was greater in individuals with better performance (i.e., men and young adults) (p < 0.001), indicating a ceiling effect of the formula in well‐functioning and younger individuals. Likewise, ICC's between both methodologies showed poor reliability in people aged <65 years (0.087–0.363) and moderate to good reliability in people aged ≥65 years (0.453–0.780). To conclude, participants with better SC performance are able to largely overshoot the minimal power required to ascend the stairs in a certain duration. This makes the sensor more sensitive to identify early age‐related differences compared to the formula. [ABSTRACT FROM AUTHOR]

Lower-limb muscle power should be closely monitored to prevent age-related functional ability declines. Stair-climbing (SC) power is a functionally relevant measurement of lower-limb muscle power. Body-fixed sensors can measure power production throughout the different steps of a flight of stairs to assess different aspects of performance. This study investigated: 1) power production throughout a full flight of stairs; 2) if staircases with less or more steps can provide similar information; and 3) test-retest reliability of SC power. 116 community-dwelling older adults (57 women) ascended three staircases as fast as possible: 12, 6 and 3 steps. Mean vertical power production per step was collected and analyzed using a commercial body-fixed sensor and software. Three phases were found in SC power production: 1) an acceleration phase, i.e., the power produced in step 1 (P1); 2) a phase where the highest performance (Pmax) is reached and; 3) a fatiguing phase with power loss (Ploss; only measurable on 12-step staircase). Mean power (Pmean) over the different steps was also evaluated. P1 did not differ between staircases (all p>0.05), whereas Pmax and Pmean were higher with increasing number of steps (p = 0.073 –p<0.001). P1, Pmax and Pmean were strongly correlated between staircases (r = 0.71–0.95, p<0.05). and showed good to excellent reliability (ICC = 0.66–0.95, p<0.05). Ploss showed poor reliability. To conclude, measurements of SC power production (P1, Pmax and Pmean) with a single sensor on the lower back are reliable across different staircases. A small, transportable, 3-step staircase can be used for measuring power production in clinical practices with no access to regular staircases. However, absolute values are dependent on the number of steps, indicating that measurements to track performance changes over time should always be done using an identical stair model. [ABSTRACT FROM AUTHOR]

Leg‐extensor rate of power development (RPD) decreases during aging. This study aimed to identify the underlying mechanism of the age‐related decline in RPD during a fast acceleration in terms of in vivo vastus lateralis (VL) fascicle shortening behavior. Thirty‐nine men aged between 25 and 69 years performed three maximal isokinetic leg‐extensor tests with a fixed initial acceleration of 45° knee extension in 150 ms until 340°/s knee angular velocity. RPD, VL activity, and ultrasound images were recorded to assess (relative) fascicle shortening and mean shortening velocity for the phases of electromechanical delay, pretension, and acceleration. Our findings show that fascicle shortening and mean shortening velocity during a fast action increase with aging (0.002 per year, P =.035 and 0.005 s−1 per year, P =.097, respectively), mainly due to a higher amount of shortening in the phase of electromechanical delay. The ratio of VL fascicle length over upper leg length at rest showed a negative correlation (r = −.46, P =.004) with RPD/body mass, while pennation angle at rest showed a trend toward a positive correlation (r =.28, P =.089). To conclude, our findings indicate that the ability to reach high VL fascicle shortening velocities in vivo is not reduced in older men while performing preprogrammed fast accelerations. The greater amount of fascicle shortening in old age is probably the result of age‐related differences in the tendinous properties of the muscle‐tendon complex, forcing the fascicles to shorten more in order to transmit the muscle force to the segment. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate differences in joint power generation between well-trained adult athletes and young sprinters from block clearance to initial contact of second stance. Eleven under 16 (U16) and 18 under 18 (U18) promising sprinters executed an explosive start action. Fourteen well-trained adult sprinters completed the exact same protocol. All athletes were equipped with 74 spherical reflective markers, while an opto-electronic motion analysis system consisting of 12 infrared cameras (250 Hz, MX3, Vicon, Oxford Metrics, UK) and 2 Kistler force plates (1,000 Hz) was used to collect the three-dimensional marker trajectories and ground reaction forces (Nexus, Vicon). Three-dimensional kinematics, kinetics, and power were calculated (Opensim) and time normalised from the first action after gunshot until initial contact of second stance after block clearance. This study showed that adult athletes rely on higher knee power generation during the first stance to induce longer step length and therefore higher velocity. In younger athletes, power generation of hip was more dominant. [ABSTRACT FROM AUTHOR]

Background: Good sit-to-stand (STS) performance is an important factor in maintaining functional independence. This study investigated whether free-living STS transition volume and intensity, assessed by a thigh-worn accelerometer, is associated with characteristics related to functional independence.Methods: Free-living thigh-worn accelerometry was recorded continuously for 3-7 days in a population-based sample of 75-, 80-, and 85-year-old community-dwelling people (479 participants; women n = 287, men n = 192). The records were used to evaluate the number and intensity (angular velocity of the STS phase) of STS transitions. Associations with short physical performance battery (SPPB), 5-times-sit-to-stand test (5×STS), isometric knee extension force, self-reported fear of falls, and self-reported difficulty in negotiating stairs were also assessed.Results: The number of STS transitions, mean and maximal angular velocity were lower in older age groups (p < .05). All variables were higher in men than in women (p < .001) and were positively associated with SPPB total points, knee extension force (r ranged from 0.18 to 0.39, all p < .001) and negatively associated with 5×STS (r = -0.13 - -0.24, all p < .05), lower extremity functional limitations (p < .01), fear of falls (p < .01), and stair negotiation difficulties (p < .01).Conclusions: Free-living STS characteristics were related to lower-extremity performance, lower extremity functional limitations, self-reported fear of falls, and stair negotiation difficulties, which can be a sensitive indicator of impending functional decline. Moreover, STS transitions may provide an indicator of adequacy of lower-limb muscle strength among older individuals. [ABSTRACT FROM AUTHOR]

The article reports on research which investigated the vibration transmission from a vibration platform through Vectran cables to the upper body and its relationship to induced muscular activation. Researchers evaluated 15 subjects who performed the biceps curl, the triceps curl and the lateral raise. They found that a cable-pulley resistance system on a vibration platform channels the vibration safely from the platform to the arms and induces additional muscle activation in some arm muscles when biceps curl exercises are performed.

The article discusses research investigating how step characteristics contribute to sprint running performance in high-level male and female athletes. The authors examined the interaction between step length and step rate and its impact on performance in sprinters during initial acceleration (IA), transition phase (TP), and at maximal speed (MS). Data collection using a laser system (ULS) and the results of the authors' data analysis are discussed.

Abstract: This randomized controlled trial investigated the effects of a 12 month whole body vibration training program on postural control in healthy older adults. Two hundred and twenty people were randomly assigned to a whole body vibration group (n =94), a fitness group (n =60) or a control group (n =66). The whole body vibration and fitness groups trained three times a week for 1 year. The vibration group performed exercises on a vibration platform and the fitness group performed cardiovascular, strength, balance and stretching exercises. Balance was measured using dynamic computerized posturography at baseline and after 6 and 12 months. Whole body vibration training was associated with reduced falls frequency on a moving platform when vision was disturbed and improvements in the response to toes down rotations at the ankle induced by the moving platform. The fitness group showed reduced falls frequency on the moving surface when vision was disturbed. Thus, whole body vibration training may improve some aspects of postural control in community dwelling older individuals. [Copyright &y& Elsevier]

This study analyzed leg muscle activity during whole-body vibration (WBV) training. Subjects performed standard unloaded isometric exercises on a vibrating platform (Power Plate): high squat (HS), low squat (LS), and 1-legged squat (OL). Muscle activity of the rectus femoris, vastus lateralis, vastus medialis, and gastrocnemius was recorded in 15 men (age 21.2 ± 0.8 years) through use of surface electromyography (EMG). The exercises were performed in 2 conditions: with WBV and without (control [CO]) a vibratory stimulus of 35 Hz. Muscle activation during WBV was compared with CO and with muscle activation during isolated maximal voluntary contractions (MVCs). Whole-body vibration resulted in a significantly higher (p < 0.05) EMG root-mean-square compared with CO in all muscle groups and all exercises (between 139.9 ± 17.5% and 1360.6 ± 57.5%). The increase in muscle activity caused by WBV was significantly higher (p < 0.05) in OL compared with HS and LS. In conclusion, WBV resulted in an increased activation of the leg muscles. During WBV, leg muscle activity varied between 12.6 and 82.4% of MVC values. [ABSTRACT FROM AUTHOR]

Purpose: Being able to rise from a chair is paramount for independent living and is strongly influenced by the ability of the lower limbs to exert mechanical power. This study assessed minimal thresholds of lower-limb relative muscle power required to perform the sit-to-stand (STS) task in older adults and its association with mobility limitations and disability. Methods: A total of 11,583 older adults (age, 60--103 yr) participated in this investigation. The 5-rep and 30-s versions of the STS test were used to assess chair rising ability. Relative power was calculated by the STS muscle power test. The minimum thresholds of power required to perform the STS tests were derived from the minimum values (i.e., "floor" effect) reported in the power tests through regression analyses. Mobility limitations and disability in activities of daily living (ADL)were recorded. Results: For the average olderman and woman, the thresholds to complete five STS repetitions were 1.1 and 1.0 W⋅ kg-1, respectively, whereas the thresholds to complete one STS repetitionwere 0.3 W⋅ kg-1 in both sexes. These thresholds increased linearly with height (5-and 1-rep, respectively: +0.13 and +0.03 W⋅ kg-1 per 10-cm increase; both P < 0.001) and did not differ by sex or testing condition (both P ≥ 0.259). All participants with relative power below the 5-rep threshold presented mobility limitations, and 51%--56% of women and 36%--49% of men also showed disability in ADL (all χ² ≥ 290.4; P < 0.001). Conclusion: A minimum level of relative muscle power is required to rise from a chair independently, which depends on the individual height and is associated with increased mobility limitations and disability. This information will help interpret data yielded by the STS muscle power test and may contribute to the prevention and treatment of mobility limitations in older people. [ABSTRACT FROM AUTHOR]

Reduced muscle performance, related to the loss of muscle mass and strength, is a common and natural part of ageing. Nevertheless, it is generally believed that regular participation in activities of moderate intensity may slow down these age-related changes. This study investigated the relationship between the habitual level of physical activity (PA), assessed by the modified Baecke Questionnaire, and the mechanical and fatigue characteristics of the right elbow flexor muscles, m. biceps brachii and m. brachioradialis, in men over the age of 55 years. Muscle fatigue was quantified both by measuring the maximal voluntary contraction (MVC) torque before and after a sustained isometric contraction at 25% MVC until exhaustion, and also by the temporal changes observed in the surface electromyographic (EMG) signal recorded during the fatigue task. Results showed a decreased MVC torque at the end of the fatiguing contraction. After 20 min of recovery, the MVC force was still significantly lower than the pre-fatigue value, except for the most active subjects. Typical myoelectrical indications of fatigue were also observed: a shift in the frequency spectrum of the signal towards lower frequencies accompanied by an increase in the EMG amplitude. We concluded from this study that the level of PA was related to the absolute isometric MVC values and the measurement of neuromuscular efficiency after 20 min of recovery, but did not influence the indications of muscle fatigue during an isometric fatigue task. [ABSTRACT FROM AUTHOR]

Power declines at a greater rate during ageing and is more relevant for functional deterioration than either loss of maximum strength or muscle mass. Human movement typically consists of stretch-shortening cycle action. Therefore, plyometric exercises, using an eccentric phase quickly followed by a concentric phase to optimize power production, should resemble daily function more than traditional resistance training, which primarily builds force production capacity in general. However, it is unclear whether older adults can sustain such high-impact training. This study compared the effects of plyometric exercise (PLYO) on power, force production, jump and functional performance to traditional resistance training (RT) and walking (WALK) in older men. Importantly, feasibility was investigated. Forty men (69.5 ± 3.9 years) were randomized to 12-weeks of PLYO (N = 14), RT (N = 12) or WALK (N = 14). Leg press one-repetition maximum (1-RM), leg-extensor isometric maximum voluntary contraction (MVC) and rate of force development (RFD), jump and functional performance were evaluated pre- and post-intervention. One subject in RT (low back pain) and three in PLYO (2 muscle strains, 1 knee pain) dropped out. Adherence to (91.2 ± 4.4%) and acceptability of (≥ 7/10) PLYO was high. 1-RM improved more in RT (25.0 ± 10.0%) and PLYO (23.0 ± 13.6%) than in WALK (2.9 ± 13.7%) (p < 0.001). PLYO improved more on jump height, jump power, contraction time of jumps and stair climbing performance compared to WALK and/or RT (p < 0.05). MVC improved in RT only (p = 0.028) and RFD did not improve (p > 0.05). To conclude, PLYO is beneficial over RT for improving power, jump and stair climbing performance without compromising gains in strength. This form of training seems feasible, but contains an inherent higher risk for injuries, which should be taken into account when designing programs for older adults. [ABSTRACT FROM AUTHOR]

Abstract Aim Task-specific exercises such as bench stepping can improve functional ability and reduce falling incidents in older adults. However, such exercises are often not optimized to improve muscle volume and force-velocity characteristics. This study determined the effects of a 12-week stepping program using incremental step heights (STEEP), on muscle volume, strength, power, functional ability and balance performance in older women. Methods Forty-five community-dwelling women (69y ± 4) were randomly assigned to the STEEP group or a non-training CONTROL group. Training intensity was primarily determined by step height, while training volume remained equal. Thigh muscle volume (CT-scan), force-velocity characteristics of the knee extensors (Biodex dynamometer) and functional ability (Short Physical Performance Battery, timed stair ascent, 10-m walk test and countermovement jump height) were determined pre- and post-intervention. In addition, 3D trunk accelerations were recorded at the lower back to assess balance during the Short Physical Performance Battery balance tests. Results Two-way ANOVA showed that the STEEP program increased thigh muscle volume, knee extensor isometric peak torque, dynamic peak power, unloaded rate of velocity development and improved performance on all functional tests to a greater extent than CONTROL (p <.05), except the countermovement jump. No improvements were found for peak velocity and balance performance (p >.05). Conclusion Our results indicate that bench step training with incremental step heights simultaneously improves functional ability, thigh muscle volume and force-velocity characteristics of the knee extensors in older women. Highlights • Bench stepping with incremental height improves strength and functional performance. • Twelve weeks of bench stepping with incremental height increases muscle volume. • Improvements in power were mediated by increased strength rather than velocity. • Bench stepping did not improve bipedal standing balance in healthy older women. • Older women reported positive feelings towards bench stepping exercise. [ABSTRACT FROM AUTHOR]

Purpose: The rate of power development (RPD) represents the capacity to rapidly generate power during a dynamic muscle contraction. As RPD is highly susceptible to aging, its decline can have important functional consequences. However, the effect of age on RPD in response to rapid changes in movement velocity (cfr. fall incidence) is not yet clear. Therefore, the present study aimed to examine the effect of age on RPD and neural drive in response to different accelerations.Methods: Three maximal isokinetic leg extensor tests at 540°/s with different initial acceleration phases at 3200, 5700 and 7200°/s2 were performed. RPD, which is the slope of the power-time curve during the acceleration phase, was calculated for 83 subjects aged between 20 and 69 years. Mean electromyography signal amplitude was determined for rectus femoris (RF), vastus lateralis (VL) and biceps femoris muscles.Results: The average annual age-related decline rate of RPD at highest acceleration was - 2.93% and was - 1.52% and - 1.82% higher compared to lower acceleration rates (p < 0.001). This deficit can probably be explained by an age-related impairment in neural drive during the first 75 ms of the acceleration phase, as evidenced by a reduced RF and VL neuromuscular activity of - 0.30% and - 0.36% at highest versus lowest acceleration (p < 0.05).Conclusion: These findings highlight the inability of aged individuals to quickly respond to abrupt changes in movement velocity, which requires more focus in training and prevention programs. [ABSTRACT FROM AUTHOR]

Human ageing is accompanied by a progressive decline in leg-extensor power (LEP). LEP is typically measured with specialized and expensive equipment, which limits the large-scale applicability. Previously, sensor-based trunk kinematics have been used to estimate the vertical power required to elevate the body’s center of mass during functional tests, but the link with LEP and age remains to be investigated. Therefore, we investigated whether a body-fixed sensor-based analysis of power during stair ascent (SA) and sit-to-stand (STS) is positively related to LEP and whether its ability to detect age-related declines is similar. In addition, the effect of load during SA and STS was investigated. 98 adults (20–70 years) performed a leg press to assess LEP, SA and 5-repetition STS tests. In SA and STS, two conditions were tested: unloaded and loaded (+10% body mass). An inertial measurement unit was used to analyze (sub)-durations and vertical power. SA and STS power were more related to LEP than duration parameters (i.e. 0.80–0.81 for power and -0.41 –-0.66 for duration parameters, p < 0.05). The average annual age-related percent change was higher in SA power (-1.38%) than in LEP (-0.86%) and STS power (-0.38%) (p < 0.05). Age explained 29% in SA power (p < 0.001), as opposed to 14% in LEP (p < 0.001) and a non-significant 2% in STS power (p = 0.102). The addition of 10% load did not influence the age-related decline of SA and STS power nor the relationship with LEP. These results demonstrate the potential of SA tests to detect age-related deterioration in neuromuscular function. SA seems more sensitive to detect age-related changes than LEP, probably because of the additional balance component and plantar- and dorsiflexor activity. On the contrary, STS is less sensitive to age-related changes because of a ceiling effect in well-functioning adults. [ABSTRACT FROM AUTHOR]

Estimating lower-limb muscle power during sit-to-stand (STS) tests is feasible for large-scale implementation. This study investigated 1) whether age, functional limitations and sex have an influence on the movement strategy and power production during STS; and 2) potential differences between STS power estimated with either a simple equation or a sensor. Five-repetition STS data of 649 subjects (♂352 ♀297) aged 19 to 93 years were included. Subjects were divided in different age groups and levels of functioning. A body-fixed sensor measured (sub)durations, trunk movement (flexion/extension) and STS muscle power (P sensor). Additionally, mean STS muscle power was calculated by a mathematic equation (Alcazar et al., 2018b) P formula. Results revealed that 1) older subjects and women showed greater trunk flexion before standing up than younger subjects and men, respectively (both p < 0.001); 2) well-functioning adults seemed to have the tendency to not extend the trunk fully during the sit-to-stand transition (mean difference extension – flexion range = −15.3° to −13.1°, p < 0.001); 3) mobility-limited older adults spent more time in the static sitting and standing positions than their well-functioning counterparts (all p < 0.001); 4) STS power decreased with age and was lower in women and in limited-functioning subjects compared to men and well-functioning subjects, respectively (p < 0.05); 5) P formula was highly related to P sensor (ICC = 0.902, p < 0.001); and 6) P formula demonstrated higher values than P sensor in well-functioning adults [mean difference = −0.31 W/kg and −0.22 W/kg for men and women, respectively (p < 0.001)], but not among limited-functioning older adults. To conclude, this study showed that age and functional limitations have an influence on the movement strategy during a 5-repetition STS test. Differences in movement strategy can affect the comparison between P formula and P sensor. In well-functioning older adults, P formula was slightly higher than P sensor , which might be related to an incomplete extension in the sit-to-stand transition. • Sensor- and equation-based sit-to-stand power are highly related. • Older adults use more trunk flexion than young adults when standing up from a chair. • Limited-functioning adults spent more time in the static phases of sit-to-stand. [ABSTRACT FROM AUTHOR]

Abstract This study aims to identify a genetic predisposition score from a set of candidate gene variants that predicts the response to a one-year exercise intervention. 200 participants (aged 60–83 years) were randomly assigned to a fitness (FIT), whole-body vibration (WBV) and control group. Participants in the exercise (FIT and WBV) groups performed a one-year intervention program. Whole-body skeletal muscle mass (SMM) and isometric knee extension strength (PT IM60 ) were measured before and after the intervention. A set of 170 muscle-related single nucleotide polymorphisms (SNPs) were genotyped. Stepwise regression analysis was applied to select significantly contributing SNPs for baseline and relative change parameters. A data-driven genetic predisposition score (GPS) was calculated by adding up predisposing alleles for each of the phenotypes. GPS was calculated based on 4 to 8 SNPs which were significantly related to the corresponding phenotypes. These SNPs belong to genes that are involved in myoblast differentiation, muscle and bone growth, myofiber contraction, cytokines and DNA methylation. GPS was related to baseline PT IM60 and relative changes of SMM and PT IM60 in the exercise groups, explaining the variance of the corresponding parameter by 3.2%, 14% and 27%, respectively. Adding one increasing allele in the GPS increased baseline PTIM 60 by 4.73 Nm, and exercise-induced relative changes of SMM and PT IM60 by 1.78% and 3.86% respectively. The identified genetic predisposition scores were positively related to baseline knee extension strength and muscle adaptations to exercise in healthy elderly. These findings provide supportive genetic explanations for high and low responders in exercise-induced muscle adaptations. Highlights • Genetic predisposition score is related to knee muscle strength. • Genetic predisposition score can explain exercise-induced adaptation variability. • DNA methylation is suggested to be involved in exercise adaptations. [ABSTRACT FROM AUTHOR]

A growing body of research in elderly populations suggests that the early phase of an explosive muscle contraction (i.e., ≤200 ms) may be more functionally relevant than peak values. However, age-related variation in early phase explosive strength has never been investigated across the full-adult life span. This cross-sectional study investigated the age-related changes in the rate of power development (RPD) and compared it to the changes in peak power (P peak ), both in terms of magnitude and onset, across the adult life span. Age-related declines in power and determinants of muscle power were compared between sexes. 1387 adults (♂813, ♀574), aged 18–78 years, performed three maximal isoinertial knee extensor tests at 20% of their isometric maximum on a Biodex dynamometer. P peak was calculated as the highest value and RPD as the linear slope of the power-time curve. Velocity (v) and torque (T) at P peak were registered. In both men and women, the decline in P peak and RPD was already apparent from 40 years onwards. Annual percent decline rates were greater for RPD (−1.1% for men and −1.3% for women) than P peak (−0.9% for men and −1.0% for women). Velocity at P peak showed the lowest annual percent decline rates (−0.3% for men and −0.4% for women). Men performed better than women on all parameters (all p < 0.001). Velocity at P peak tended to decline more in women than in men (p = 0.065). To conclude, both knee extensor P peak and RPD can be used to screen for age-related neuromuscular weaknesses at an early age. Both sexes seem equally susceptible to age-related declines in knee extensor power. In addition to traditional slow-speed resistance exercise, prevention strategies should include explosive exercises. Explosive exercises may be especially relevant in women, considering that they tend to decline more in the velocity component of muscle power. [ABSTRACT FROM AUTHOR]

Rapid muscle characteristics, such as the rate of power development (RPD), are shown to decline more than maximal muscle characteristics during ageing in single-joint actions. However, functional disability is mainly the result of multi-joint lower limb failure. The complex activation patterns inherent to multi-joint actions and the deteriorating effect of age on that neural drive suggest a larger effect of age on RPD multi-joint. Yet, this is the first study that compared multi- with single-joint leg extension tests in terms of RPD across the adult life span and assessed its transferability to functional performance. 96 healthy adults (♂ 49, ♀ 47, age = 20–69 years) performed dynamic single-joint knee-extension tests on a Biodex System 3 dynamometer and multi-joint leg-extension tests on a custom-made device at low, moderate and high speed. Peak power (Ppeak) was calculated as the highest value of the power-time curve and RPD as the linear slope till isokinetic speed was reached. Functional performance was tested using squat jump height. RPD showed greater age-related declines in multi-joint (−1.92%/year) versus single-joint (−1.42%/year) actions, which is in contrast with the finding of Ppeak (−0.77% vs. –1.04%/year). Squat jump height was more strongly associated with RPD multi-joint than single-joint ( r  = 0.77–0.82 vs. 0.44–0.61). These results show greater age-related declines of RPD multi-joint versus single-joint and demonstrate its functional relevance. We believe that this finding may be of high importance for the detection and prevention of functional disability during ageing. [ABSTRACT FROM AUTHOR]

Isotonic testing and measures of rapid power production are emerging as functionally relevant test methods for detection of muscle aging. Our objective was to assess reliability of rapid velocity and power measures in older adults using the isotonic mode of an isokinetic dynamometer. Sixty-three participants (aged 65 to 82 years) underwent a test-retest protocol with one week time interval. Isotonic knee extension tests were performed at four different loads: 0%, 25%, 50% and 75% of maximal isometric strength. Peak velocity (pV) and power (pP) were determined as the highest values of the velocity and power curve. Rate of velocity (RVD) and power development (RPD) were calculated as the linear slopes of the velocity- and power-time curve. Relative and absolute measures of test-retest reliability were analyzed using intraclass correlation coefficients (ICC), standard error of measurement (SEM) and Bland-Altman analyses. Overall, reliability was high for pV, pP, RVD and RPD at 0%, 25% and 50% load (ICC: .85 - .98, SEM: 3% - 10%). A trend for increased reliability at lower loads seemed apparent. The tests at 75% load led to range of motion failure and should be avoided. In addition, results demonstrated that caution is advised when interpreting early phase results (first 50ms). To conclude, our results support the use of the isotonic mode of an isokinetic dynamometer for testing rapid power and velocity characteristics in older adults, which is of high clinical relevance given that these muscle characteristics are emerging as the primary outcomes for preventive and rehabilitative interventions in aging research. [ABSTRACT FROM AUTHOR]

Purpose: To assess whether stepping-based weight bearing exercise (WBE) can elicit peak activation of upper leg muscles similar to resistance exercise (RE) at an intensity required to induce strength gains in elderly women.Methods: Muscular activation of several upper leg muscles was measured during RE and WBE in a cohort of 19 healthy elderly women (69.3 ± 3.4 years). WBE consisted of forward and lateral stepping with step heights of 10, 20 and 30 cm. Muscular activation was compared to 60% of one-repetition maximum (1-RM) of congruent RE.Results: Peak activation during WBE was higher than RE at 60% 1-RM during forward and lateral stepping in vastus lateralis starting at 20 cm (p = 0.049 and p = 0.001), and biceps femoris at 30 cm step height (p = 0.024 and p = 0.030). Gluteus maximus peak activation matched RE at 60% 1-RM at 20 and 30 cm step height regardless of step direction (p ≥ 0.077). Peak activation of the rectus femoris and gluteus medius matched RE activation at 60% 1-RM during lateral stepping at 30 cm (p = 0.355 and p = 0.243, respectively) but not during forward stepping. WBE did not induce similar activation as RE in the semitendinosus.Conclusion: In WBE, most upper leg muscles were recruited at an equal or higher intensity than in RE at 60% 1-RM. Lateral stepping at 30 cm step height showed the highest training potential of all WBE's applied. [ABSTRACT FROM AUTHOR]

Research underlines the potential of low-load resistance exercise in older adults. However, while the effects of detraining from high-load protocols have been established, it is not known whether gains from low-load training would be better/worse maintained. The current study evaluated the effects of 24 weeks of detraining that followed 12 weeks of high- and low-load resistance exercise in older adults. Fifty-six older adults (68.0 ± 5.0 years) were randomly assigned to leg press and leg extension training at either HIGH load (2 × 10–15 repetitions at 80% of one-repetition maximum (1-RM)), LOW load (1 × 80–100 repetitions at 20% of 1-RM), or LOW + load (1 × 60 repetitions at 20% of 1-RM, immediately followed by 1 × 10–20 repetitions at 40% 1-RM). All protocols ended with volitional fatigue. The main outcome measures included mid-thigh muscle volume, leg press 1-RM, leg extension isometric and isokinetic strength, and functional performance. Tests were performed at baseline, post-intervention and after 24 weeks of detraining. Results show no effect of load on preservation of muscle volume, which returned to baseline after detraining. Training-induced gains in functional capacity and isometric strength were maintained, independent of load. HIGH and LOW + were more beneficial than LOW for long-lasting gains in training-specific 1-RM. To conclude, gains in muscle volume are reversed after 24 weeks of detraining, independent of load. This emphasises the need for long-term resistance exercise adherence. The magnitude of detraining in neuromuscular and functional adaptations was similar between groups. These findings underline the value of low-load resistance exercise in older age. Clinical Trial Registration NCT01707017 . [ABSTRACT FROM AUTHOR]

Background Literature reports on the effects of resistance training on heat shock protein70 (Hsp70) adaptation in older subjects are scarce. Moreover, the optimum training load required to obtain a beneficial adaptation profile is lacking. Therefore, the aim of this study was to determine the effects of resistance training at various external loads on extracellular Hsp70 (eHsp70) resting levels in older humans. Methods Fifty-six community-dwelling older (68 ± 5 years) volunteers were randomized to 12 weeks of resistance training (3 ×/week) at either high-resistance (HIGH, 8 males, 10 females, 2 × 10–15 repetitions at 80% 1RM), low resistance (LOW, 9 Males, 10 Females, 1 × 80–100 repetitions at 20% 1RM), or mixed low resistance (LOW +, 9 Males, 10 Females, 1 × 60 repetitions at 20% 1RM followed by 1 × 10–20 repetitions at 40% 1RM). Serum was available from 48 out of the 56 participants at baseline and after 12 weeks for determination of eHsp70. Mid-thigh muscle volume (computed tomography), muscle strength (1RM & Biodex dynamometer) and physical functioning (including 6 min walk distance [6MWD]) were assessed. Results There was a sex-related dichotomy in the heat shock response to high external load training. We observed a significant decrease in eHsp70 concentration in the HIGH group for female, but not male, subjects. At baseline, men had a larger muscle volume, leg press and leg extension 1RM compared to women (all p < 0.001). Also, the 6MWD was significantly higher in men compared to women at baseline. However, this difference disappeared when correcting for height. Moreover, the overall functional performance and physical activity scores were similar in men and women. None of the participants' characteristics nor any of the outcome variables differed between groups at baseline. There was a significant increase in the strength and physical performance parameters in both men and women post-exercise (all p < 0.05). Females in the HIGH group clearly demonstrated a larger gain in leg press 1RM and the isometric knee extensor strength compared to females in the LOW group (p = 0.036 and p = 0.044, respectively). More so, we found an inverse association between the change in eHsp70 levels and improvement in isometric knee extensor strength and 6MWD (r = − 0.443, p = 0.002 and r = − 0.428, p = 0.002; respectively) post exercise. Conclusions Our results show that resistance training at high external load decreases the resting levels of eHsp70 in older females. Whether this reflects a better health status requires further investigation. [ABSTRACT FROM AUTHOR]

Objective To evaluate the feasibility and short- and long-term effects of two 10-wk structured ergometer-cycling programs among elderly in assisted-living residences. Design, setting, and participants Eight assisted-living residences (N = 95; age = 81.2 ± 5.9 years) were randomly assigned to one of three conditions: 1) ergometer-cycling with strict coach-supervision (STRICT, N = 3; n = 35); 2) ergometer-cycling with autonomy-supportive minimal contact coach-supervision (AUT; N = 3; n = 36); or 3) control condition (CON; N = 2, n = 24). Intervention Three-weekly progressive ergometer-cycling sessions for 10 weeks. Main outcome measures Feasibility, physical activity (PA), muscular strength, functional performance and quality of life (baseline, post-intervention (10weeks) and 6-month follow-up). Results 83 participants were analyzed post-intervention, 75 at follow-up. Adherence was higher in STRICT than AUT during the intervention ( p = 0.001), but not during follow-up. Compared with CON, both programs showed positive short- and long-term effects on moderate-intensity PA ( p = 0.034). With regard to strength, functional performance and well-being, no time-by-group interaction effects were found. When comparing high-adherers (adherence ≥ 80%) to low-adherers, a greater increase in functional performance and in well-being and a trend towards a lower decrease in strength were found in the short-term ( p = 0.047, p < 0.001 and p = 0.054, respectively). Conclusion Both interventions were feasible and equally effective to increase long-term engagement in PA, irrespective of the type of supervision. When adherence is high, positive effects on strength, performance and well-being can be expected. [ABSTRACT FROM AUTHOR]

Purpose: Suppressing inflammaging at an early stage in life via exercise might prevent chronic diseases later in life. The aim was to investigate the influence of resistance training at different external loads on inflammatory markers in healthy young adults.Methods: Serum was collected for basal levels of cytokines (IL-1beta, IL-6, IL-8, sTNFR1, IL-1RA, IL-10 and GM-CSF) before and after 9 weeks exercise from 36 young (22 ± 2 years) healthy subjects who were randomized to three times weekly supervised resistance training at either HImax (n = 12, 1 × 10-12 repetitions at 80% 1RM), LO (n = 12, 1 × 10-12 repetitions at 40% 1RM), or LOmax (n = 12, 1 × 10-12 repetitions at 40% 1RM preceded by 60 repetitions at 20-25% 1RM) respectively.Results: Overall, IL-8 increased (p < 0.001) and IL-6 decreased (p = 0.001) after training, but no significant time*group interaction was found (respectively, p = 0.283 and p = 0.058 for IL-8 and IL-6). When analyzed separately, IL-8 increased significantly in HImax (p = 0.022) and LOmax (p = 0.024); and IL-6 decreased significantly in LOmax (p = 0.009) and LO (p = 0.013). No significant overall time effect was observed for sTNFR1 and IL-1RA; however, in HImax sTNFR1 (p = 0.031) and IL-1RA (p = 0.014) increased significantly, but remained unchanged in LOmax and LO. IL-1beta, IL-10 and GM-CSF levels remained undetectable in most participants.Conclusions: Nine weeks of resistance training-irrespective of the external load-have beneficial effects on circulating IL-8 and IL-6. In addition, training at high external load increases the anti-inflammatory cytokines sTNFR1 and IL-1RA. The results of this study show that resistance training has anti-inflammatory effects in healthy young persons and that the response of the different inflammatory mediators depends on the magnitude of the external load. [ABSTRACT FROM AUTHOR]

Background Little is known about the effects of resistance training (RT) on circulating cytokines in older adults. Also, dose-response relationships remain unclear. This study investigated the impact of RT at different external loads on circulating inflammatory mediators in older community-dwelling individuals. Methods Fifty-six community-dwelling older (68 ± 5 years) volunteers were randomized to 12 weeks of supervised RT (×3/week) at either high-resistance training [8 males, 10 females, 2 × 10–15 repetitions at 80% 1 repetition maximum (RM)], low-resistance training (9 males, 10 females, 1 × 80–100 repetitions at 20% 1 RM), or mixed low-resistance training (9 males, 10 females, 1 × 60 repetitions at 20% 1 RM followed by 1 × 10–20 repetitions at 40% 1 RM). Serum was available from 51 out of 56 participants at baseline and after 12 weeks for determination of interleukin (IL)-6, IL-8, IL-10, IL-1β, soluble tumor necrosis factor receptor (sTNFR)1, granulocyte macrophage colony-stimulating factor, and IL-1 receptor antagonist (ra). Results Twelve weeks of RT significantly increased sTNFR1 from 2.48 ± 0.57 ng/mL to 2.58 ± 0.59 ng/mL (overall time-effect P = .033) and Log IL-8 from 0.38 ± 0.18 pg/mL to 0.53 ± 0.32 pg/mL (overall time-effect P = .007). No time X group interaction ( P = .916) was observed. In males of the high-resistance training group, there was an increase in Log IL-8 (from 0.45 ± 0.16 pg/mL to 0.68 ± 0.19 pg/mL; P = .005) and IL-1ra (from 68.60 ± 24.12 pg/mL to 79.56 ± 29.07 pg/mL; P = .007). No significant changes were found for the other markers. Conclusions Our results show that 12 weeks of supervised RT induced an overall significant increase of circulating IL-8 and sTNFR1, independently from the external load applied. We suggest that exercising until volitional fatigue is the main trigger for exercise-induced responses. However, training at high external load also increased anti-inflammatory IL-1ra in male participants, which might be beneficial in combating low-grade inflammation. [ABSTRACT FROM AUTHOR]

Aging is a complex process that is accompanied with changes in both muscle mass and muscle function (strength and performance). Therefore, the current longitudinal study aimed to provide a better insight in 10-year aging-related changes in whole-body muscle mass and strength performance of the leg extensors during the adult life span. Data were gathered within the framework of the first- (2002–2004: baseline) and third-generation Flemish Policy Research Center Sport (2012–2014: follow-up). Results are based on muscle characteristics data of 591 Flemish Caucasian adults (19–73 years, 381 men). Skeletal muscle mass (SMM) was determined with bioelectrical impedance analysis. Biodex Medical System 3® dynamometer was used to measure isometric (PTstatic120°) and isokinetic (PTdynamic60° and PTdynamic240°) strength, ballistic movement speed (S20 %), and muscular endurance (work) of the knee extensors. Overall strength performance was higher at both evaluation moments in men compared to women (p < 0.01). But only S20 % declined significantly faster in men compared to women (p < 0.01). Age and baseline strength performance were negatively related with the change in strength performance, even when corrected for SMM, protein intake, and energy expenditure during sports (Esport). In conclusion, strength performance was not associated with Esport in this study, but protein intake was associated with isometric strength in men, and with ballistic and isokinetic strength in women. Changes in S20 % were significantly greater in men compared to women. Baseline values of strength performance and age were associated with changes in strength performance parameters, even after correction for SMM, protein intake, and Esport. [ABSTRACT FROM AUTHOR]

Background BDNF is known to induce neuroplasticity and low circulating levels have been related to neuronal loss in older persons. Physical exercise is thought to trigger BDNF-induced neuroplasticity, but conflicting observations have been reported regarding the effects of resistance training on circulating BDNF in the elderly. These conflicting observations might reflect dose-and gender-specific differences. Method Fifty-six apparently healthy elderly (68 ± 5 years) participants were randomized to 12 weeks of resistance training (3 ×/week) at either high-resistance (HIGH, 8 Males, 10 Females, 2 × 10–15 repetitions at 80% 1RM), low-resistance (LOW, 9 Males, 10 Females, 1 × 80–100 repetitions at 20% 1RM), or mixed low-resistance (LOW +, 9 Males, 10 Females, 1 × 60 repetitions at 20% 1RM followed by 1 × 10–20 repetitions at 40% 1RM). Serum was collected for BDNF assay at baseline and after 12 weeks (24 h–48 h after the last training). Results 12 weeks of LOW + exercise significantly increased BDNF levels in male (from 34.9 ± 10.7 ng/mL to 42.9 ± 11.9 ng/mL, time × group interaction p = 0.013), but not in female participants. No significant change was observed in HIGH or LOW, neither in male nor female subjects. Conclusion Our results show that only the mixed-low-resistance training program with a very high number of repetitions at a sufficiently high external resistance was able to increase circulating BDNF in older male participants. Training to volitional fatigue might be necessary to obtain optimal results. Additional studies are needed to unravel the underlying mechanisms, as well as to confirm the observed gender difference. [ABSTRACT FROM AUTHOR]

Background: In terms of motivation and long-term adherence, low-resistance exercise might be more suitable for older adults than high-resistance exercise. However, more data are needed to support this claim.Objective: The objective was to investigate the effect of low- and high-resistance exercise protocols on long-term adherence and motivation.Methods: This study was designed as an exploratory 24-week follow-up of a randomized 12-week resistance training intervention in older adults. Participants were free to decide whether or not they continued resistance training at their own expense following the intervention. Fifty-six older adults were randomly assigned to HIGH [2 × 10-15 repetitions at 80% of one repetition maximum (1RM)], LOW (1 × 80-100 repetitions at 20% of 1RM), or LOW+ (1 × 60 repetitions at 20% of 1RM + 1 × 10-20 repetitions at 40% 1RM). Motivation, self-efficacy and the perceived barriers for continuing resistance exercise were measured after cessation of each supervised intervention and at follow-up, while long-term adherence was probed retrospectively at follow-up.Results: Participants reported high levels of self-determined motivation before, during, and after the supervised intervention, with no differences between groups (p > 0.05). Nevertheless, only few participants continued strength training after the intervention: 17% in HIGH, 21% in LOW+, and 11% in LOW (p > 0.05). The most commonly reported barriers for continuing resistance exercise were perceived lack of time (46%), being more interested in other physical activities (40%), seasonal reasons (40%), and financial cost (28%).Conclusion: The results suggest no difference in long-term adherence after the end of a supervised exercise intervention at high or low external resistances. Long-term adherence was limited despite high levels of self-determined motivation during the interventions. These findings highlight the importance of further research on developing strategies to overcome barriers of older adults to adhere to resistance exercise without supervision. [ABSTRACT FROM AUTHOR]

The article presents a study conducted on postmenopausal women to determine the effects of local vibration training performed for 6 months on the bone mineral density (BMD), muscle strength, and physical performance. Several factors that were assessed includes muscle mass after performing quadriceps, side effects of local vibration training and feasibility of the training.

Purpose: Objective methods to quantify physical activity (PA) and predict energy expenditure (EE) are needed in the old and old-old. The aim of the present study was to evaluate the validity of EE estimates by the SenseWear Mini (SWMini) compared with indirect calorimetry during daily life activities in institutionalized older adults. Methods: Sixty nursing home residents (mean age = 85.5 ± 5.5 yr) wore the SWMini during rest (sitting quietly) and three activity tasks (walking, sitting/rising/walking, and moving objects). SWMini data were processed using software version 7.0. The criterion EE (kcal⋅min-1) was estimated by a portable gas analyzer, Oxycon Mobile (OM). Results: The analyses revealed high correlations (rsitting = 0.68, ractivity tasks = 0.88) between EE estimated by OM and SWMini. EE increased between sitting periods and activity tasks for EE estimated by OM (mean difference = 61.5% ± 8.9%), as well as for EE estimated by SWMini (mean difference = 58.2% ± 7.4%) (P < 0.001). However, SWMini significantly underestimated EE, with an overall absolute percent error of 14.1% ± 7.9%. The largest absolute percent differences were observed during sitting periods compared with activity tasks (P < 0.05). Older age significantly reduced accuracy, explaining 12% of the variance in total percent error (β = 0.42, t = 2.84, P < 0.05). Conclusions: The high percent error scores indicate that the SWMini is of limited value for quantifying EE in the old and old-old. The accuracy could be improved by developing accurate age- and activity-specific algorithms. On the other hand, the SWMini can be used as a suitable device for researchers interested in specific levels and patterns of PA and sedentary behavior. [ABSTRACT FROM AUTHOR]

The present follow-up study aims at assessing the longitudinal changes in muscle quality after an interval of 9.45 years in middle-aged men. In addition, the relative contribution of muscle mass, muscle strength, and muscle power at middle age to these changes was investigated. The results showed a small, though unexpected, increase in total body and leg muscle mass (respectively 0.22 ± 0.04 and 0.29 ± 0.06 % yearly, p < 0.0001), whereas basic strength (−0.71 to −0.87 % yearly, p < 0.0001) and velocity-dependent strength and power (−1.19 to −1.86 % yearly, p < 0.0001) declined. Consequently, muscle quality, defined as the ratio of basic strength or velocity-dependent strength and power to muscle mass decreased (−1.46 to −2.43 % yearly, p < 0.0001) from baseline to follow-up. We found that baseline basic strength is a strong determinant of the decline in muscle quality basic strength with advancing age, whereas only a small part of the age-associated decline in muscle quality based on velocity-dependent strength and power could be explained. To conclude, our results indicate that muscle becomes less efficient at middle age and that baseline muscle strength is a strong predictor of this change. These findings imply that unmeasured neural factors, influencing both contraction speed and the capacity of muscle to produce strength, are possibly other involved determinants. Therefore, timely interventions including strength training and higher-velocity strength training at middle age are recommended. [ABSTRACT FROM AUTHOR]

The article focuses on a study conducted to examine the transmission of whole body vibration over a wide range of frequencies and accelerations with relation to muscle activation and body posture. It was found that whole body vibration in squat position caused contraction in all muscles even at the minimum accelerations.

The article compares the effects of training protocols of maximal effort at high and low external resistance on knee extensor force-velocity measurements in subjects performing knee extension strengthening exercises. Participants were evaluated for variables such as knee extensor torque, maximal work, and movement speed before and after the training sessions. Statistical analysis of the data found significant differences in force-velocity variables between the high and low resistance groups.