Publications by authors named "Christophe Delecluse"

71 Publications

Relative sit-to-stand power: aging trajectories, functionally relevant cut-off points, and normative data in a large European cohort.

J Cachexia Sarcopenia Muscle 2021 Aug 3;12(4):921-932. Epub 2021 Jul 3.

GENUD Toledo Research Group, Universidad de Castilla-La Mancha, Toledo, Spain.

Background: A validated, standardized, and feasible test to assess muscle power in older adults has recently been reported: the sit-to-stand (STS) muscle power test. This investigation aimed to assess the relationship between relative STS power and age and to provide normative data, cut-off points, and minimal clinically important differences (MCID) for STS power measures in older women and men.

Methods: A total of 9320 older adults (6161 women and 3159 men) aged 60-103 years and 586 young and middle-aged adults (318 women and 268 men) aged 20-60 years were included in this cross-sectional study. Relative (normalized to body mass), allometric (normalized to height squared), and specific (normalized to legs muscle mass) muscle power values were assessed by the 30 s STS power test. Body composition was evaluated by dual energy X-ray absorptiometry and bioelectrical impedance analysis, and legs skeletal muscle index (SMI; normalized to height squared) was calculated. Habitual and maximal gait speed, timed up-and-go test, and 6 min walking distance were collected as physical performance measures, and participants were classified into two groups: well-functioning and mobility-limited older adults.

Results: Relative STS power was found to decrease between 30-50 years (-0.05 W·kg ·year ; P > 0.05), 50-80 years (-0.10 to -0.13 W·kg ·year ; P < 0.001), and above 80 years (-0.07 to -0.08 W·kg ·year ; P < 0.001). A total of 1129 older women (18%) and 510 older men (16%) presented mobility limitations. Mobility-limited older adults were older and exhibited lower relative, allometric, and specific power; higher body mass index (BMI) and legs SMI (both only in women); and lower legs SMI (only in men) than their well-functioning counterparts (all P < 0.05). Normative data and cut-off points for relative, allometric, and specific STS power and for BMI and legs SMI were reported. Low relative STS power occurred below 2.1 W·kg in women (area under the curve, AUC, [95% confidence interval, CI] = 0.85 [0.84-0.87]) and below 2.6 W·kg in men (AUC [95% CI] = 0.89 [0.87-0.91]). The age-adjusted odds ratios [95% CI] for mobility limitations in older women and men with low relative STS power were 10.6 [9.0-12.6] and 14.1 [10.9-18.2], respectively. MCID values for relative STS power were 0.33 W·kg in women and 0.42 W·kg in men.

Conclusions: Relative STS power decreased significantly after the age of 50 years and was negatively and strongly associated with mobility limitations. Our study provides normative data, functionally relevant cut-off points, and MCID values for STS power for their use in daily clinical practice.
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http://dx.doi.org/10.1002/jcsm.12737DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8350203PMC
August 2021

Threshold of Relative Muscle Power Required to Rise from a Chair and Mobility Limitations and Disability in Older Adults.

Med Sci Sports Exerc 2021 Jun 7. Epub 2021 Jun 7.

GENUD Toledo Research Group, Universidad de Castilla-La Mancha. Toledo, Spain CIBER of Frailty and Healthy Aging (CIBERFES). Madrid, Spain Geriatric Research Unit, Department for Geriatric and Palliative Medicine, Bispebjerg and Frederiksberg University Hospital. Copenhagen, Denmark Geriatric Research Unit, Department of Internal Medicine, Herlev and Gentofte University Hospital, Denmark CopenAge - Copenhagen Center for Clinical Age Research, University of Copenhagen. Denmark Exercise and Health Laboratory, CIPER, Faculty of Human Motricity, University of Lisbon. Lisbon, Portugal. CIDEFES, Research Center in Sports, Physical Education and Exercise and Health, Lusofona University. Lisbon, Portugal Physical Activity, Sports and Health Research Group, Department of Movement Sciences, KU Leuven. Leuven, Belgium ImFine Research Group, Department of Health and Human Performance, Faculty of Science and Physical Activity and Sports Sciences, Polytechnic University of Madrid. Madrid, Spain CIBER of Pathophysiology of Obesity and Nutrition (CIBEROBN). Madrid, Spain Geriatric Department, Hospital Universitario de Getafe, Getafe, Spain Growth, Exercise, Nutrition, and Development Research Group, University of Zaragoza. Zaragoza, Spain Department of Internal Medicine, Geriatric Division, Amager and Hvidovre Hospital, Glostrup. Copenhagen, Denmark Geriatric Research Unit, Hospital Virgen del Valle, Complejo Hospitalario de Toledo. Toledo, Spain.

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 years old) 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 older man and woman, the thresholds to complete five STS repetitions were 1.1 and 1.0 W·kg-1, respectively, while the thresholds to complete one STS repetition were 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.
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http://dx.doi.org/10.1249/MSS.0000000000002717DOI Listing
June 2021

An age-adapted plyometric exercise program improves dynamic strength, jump performance and functional capacity in older men either similarly or more than traditional resistance training.

PLoS One 2020 25;15(8):e0237921. Epub 2020 Aug 25.

Physical Activity, Sports and Health Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium.

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.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237921PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447006PMC
October 2020

The Genetic Effect on Muscular Changes in an Older Population: A Follow-Up Study after One-Year Cessation of Structured Training.

Genes (Basel) 2020 08 21;11(9). Epub 2020 Aug 21.

Department of Movement Sciences, Physical Activity, Sports & Health Research Group, KU Leuven, 3001 Leuven, Belgium.

Older adults lose muscle mass and strength at different speeds after the cessation of physical exercise, which might be genotype related. This study aimed to explore the genetic association with changes in muscle mass and strength one year after the cessation of structured training in an older population. Participants ( = 113, aged between 61 and 81 years) who performed one-year of combined fitness ( = 44) or whole-body vibration ( = 69) training were assessed one year after the cessation of the training. Whole-body skeletal muscle mass and knee strength were measured. Data-driven genetic predisposition scores (GPSs) were calculated and analysed in a general linear model with sex, age, body mass index and post-training values of skeletal muscle mass or muscle strength as covariates. Forty-six single nucleotide polymorphisms (SNPs) from an initial 170 muscle-related SNPs were identified as being significantly linked to muscular changes after cessation. Data-driven GPSs and over time muscular changes were significantly related ( < 0.01). Participants with higher GPSs had less muscular declines during the cessation period while data-driven GPSs accounted for 26-37% of the phenotypic variances. Our findings indicate that the loss of training benefits in older adults is partially genotype related.
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http://dx.doi.org/10.3390/genes11090968DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564970PMC
August 2020

Age-related differences in vastus lateralis fascicle behavior during fast accelerative leg-extension movements.

Scand J Med Sci Sports 2020 Oct 7;30(10):1878-1887. Epub 2020 Jul 7.

Department of Movement Sciences, Human Movement Biomechanics Research Group, KU Leuven, Leuven, Belgium.

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 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.
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http://dx.doi.org/10.1111/sms.13752DOI Listing
October 2020

Corrigendum to "The effect of resistance training, detraining and retraining on muscle strength and power, myofibre size, satellite cells and myonuclei in older men" [Exp. Gerontol., 133, 2020, 110860].

Exp Gerontol 2020 Jun 6;134:110897. Epub 2020 Mar 6.

Physical Activity, Sports & Health Research Group, Department of Movement Sciences, KU Leuven - University of Leuven, Tervuursevest 101, Box 1500, 3001 Leuven, Belgium. Electronic address:

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http://dx.doi.org/10.1016/j.exger.2020.110897DOI Listing
June 2020

The effect of resistance training, detraining and retraining on muscle strength and power, myofibre size, satellite cells and myonuclei in older men.

Exp Gerontol 2020 05 1;133:110860. Epub 2020 Feb 1.

Physical Activity, Sport & Health Research Group, Department of Movement Sciences, KU Leuven - University of Leuven, Tervuursevest 101, Box 1500, 3001 Leuven, Belgium. Electronic address:

Introduction: Ageing is associated with an attenuated hypertrophic response to resistance training and periods of training interruptions. Hence, elderly would benefit from the 'muscle memory' effects of resistance training on muscle strength and mass during detraining and retraining. As the underlying mechanisms are not yet clear, this study investigated the role of myonuclei during training, detraining and retraining by using PCM1 labelling in muscle cross-sections of six older men.

Methods: Knee extension strength and power were measured in 30 older men and 10 controls before and after 12 weeks resistance training and after detraining and retraining of similar length. In a subset, muscle biopsies from the vastus lateralis were taken for analysis of fibre size, fibre type distribution, Pax7+ satellite cell number and myonuclear domain size.

Results: Resistance training increased knee extension strength and power parameters (+10 to +36%, p < .001) and decreased the frequency of type IIax fibres by half (from 20 to 10%, p = .034). Detraining resulted in a modest loss of strength and power (-5 to -15%, p ≤ .004) and a trend towards a fibre-type specific decrease in type II fibre cross-sectional area (-17%, p = .087), type II satellite cell number (-30%, p = .054) and type II myonuclear number (-12%, p = .084). Less than eight weeks of retraining were needed to reach the post-training level of one-repetition maximum strength. Twelve weeks of retraining were associated with type II fibre hypertrophy (+29%, p = .050), which also promoted an increase in the number of satellite cells (+72%, p = .036) and myonuclei (+13%, p = .048) in type II fibres. Changes in the type II fibre cross-sectional area were positively correlated with changes in the myonuclear number (Pearson's r between 0.40 and 0.73), resulting in a stable myonuclear domain.

Conclusion: Gained strength and power and fibre type changes were partially preserved following 12 weeks of detraining, allowing for a fast recovery of the 1RM performance following retraining. Myonuclear number tended to follow individual changes in type II fibre size, which is in support of the myonuclear domain theory.
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http://dx.doi.org/10.1016/j.exger.2020.110860DOI Listing
May 2020

Differences in Maximum Voluntary Excitation Between Isometric and Dynamic Contractions are Age-Dependent.

J Appl Biomech 2019 Jun 5;35(3):196-201. Epub 2019 May 5.

1 KU Leuven.

Obtaining true maximum voluntary excitation appears to be more difficult in older populations than in young populations. The aims of this study were (1) to determine whether differences in maximum voluntary excitation obtained from maximum voluntary isometric contraction (MVIC) and (sub-)maximum voluntary dynamic contraction [(s-)MVDC] are age dependent, and (2) to determine how normalizing electromyographic signals to corresponding maximum voluntary excitations affects variance between participants and the likelihood of normalized signals exceeding 100%. MVIC, s-MVDC, and MVDC were recorded in 10 young women, and MVIC and s-MVDC were recorded in 19 older women. A significant age × contraction mode interaction effect was found for vastus lateralis ( = .04). In young women, MVDC elicited the highest maximum voluntary excitation for vastus lateralis and rectus femoris ( < .05). In older women, no differences in maximum voluntary excitation were found ( > .05). Normalization to dynamic contractions resulted in lower between-participant variance of electromyography amplitudes, though not for all muscles, and decreased the number of normalized signals exceeding 100% in young women. These findings indicate that differences in maximum voluntary excitation across contraction modes are age dependent. Therefore, one should be cautious when comparing normalized signals between age groups; however, overall dynamic contractions may be preferable over isometric contractions for normalization purposes.
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http://dx.doi.org/10.1123/jab.2018-0215DOI Listing
June 2019

Bench stepping with incremental heights improves muscle volume, strength and functional performance in older women.

Exp Gerontol 2019 06 22;120:6-14. Epub 2019 Feb 22.

Department of Movement Sciences, Physical Activity, Sports and Health Research Group, KU Leuven, Leuven, Belgium.

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.
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http://dx.doi.org/10.1016/j.exger.2019.02.013DOI Listing
June 2019

Effect of acceleration on the rate of power development and neural activity of the leg extensors across the adult life span.

Eur J Appl Physiol 2019 Mar 7;119(3):781-789. Epub 2019 Feb 7.

Physical Activity, Sports and Health Research Group, Department of Movement Sciences, Faculty of Movement and Rehabilitation Sciences, KU Leuven, Tervuursevest 101, 3001, Leuven, Belgium.

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°/s 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.
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http://dx.doi.org/10.1007/s00421-018-04069-3DOI Listing
March 2019

A body-fixed-sensor-based analysis of stair ascent and sit-to-stand to detect age-related differences in leg-extensor power.

PLoS One 2019 17;14(1):e0210653. Epub 2019 Jan 17.

Department of Movement Sciences, Physical Activity, Sports and Health Research Group, KU Leuven, Leuven, Belgium.

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.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210653PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336282PMC
October 2019

Muscle-tendon unit length changes differ between young and adult sprinters in the first stance phase of sprint running.

R Soc Open Sci 2018 Jun 13;5(6):180332. Epub 2018 Jun 13.

KU Leuven - University of Leuven Department of Kinesiology, Human Movement Biomechanics Research Group, 3000 Leuven, Belgium.

The aim of this study was to compare young and adult sprinters on several biomechanical parameters that were previously highlighted as performance-related and to determine the behaviour of several muscle-tendon units (MTU) in the first stance phase following a block start in sprint running. The ground reaction force (GRF) and kinematic data were collected from 16 adult and 21 young well-trained sprinters. No difference between the groups was found in some of the previously highlighted performance-related parameters (ankle joint stiffness, the range of dorsiflexion and plantar flexor moment). Interestingly, the young sprinters showed a greater maximal and mean ratio of horizontal to total GRF, which was mainly attributed to a greater horizontal GRF relative to body mass and resulted in a greater change in horizontal centre of mass (COM) velocity during the stance phase in the young compared with the adult sprinters. Results from the MTU length analyses showed that adult sprinters had more MTU shortening and higher maximal MTU shortening velocities in all plantar flexors and the rectus femoris. Although previously highlighted performance-related parameters could not explain the greater 100 m sprinting times in the adult sprinters, differences were found in the behaviour of the MTU of the plantar flexors and rectus femoris during the first stance phase. The pattern of length changes in these MTUs provides ideal conditions for the use of elastic energy storage and release for power enhancement.
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http://dx.doi.org/10.1098/rsos.180332DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6030344PMC
June 2018

Genetic predisposition score predicts the increases of knee strength and muscle mass after one-year exercise in healthy elderly.

Exp Gerontol 2018 10 4;111:17-26. Epub 2018 Jul 4.

Department of Movement Sciences, Physical Activity, Sports & Health Research Group, KU Leuven, Leuven, Belgium. Electronic address:

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) 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 and relative changes of SMM and PT 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 by 4.73 Nm, and exercise-induced relative changes of SMM and PT 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.
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http://dx.doi.org/10.1016/j.exger.2018.06.030DOI Listing
October 2018

Rate of power development of the knee extensors across the adult life span: A cross-sectional study in 1387 Flemish Caucasians.

Exp Gerontol 2018 09 25;110:260-266. Epub 2018 Jun 25.

KU Leuven, Department of Movement Sciences, Physical Activity, Sports and Health Research Group, Belgium.

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), 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 was calculated as the highest value and RPD as the linear slope of the power-time curve. Velocity (v) and torque (T) at P were registered. In both men and women, the decline in P 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 (-0.9% for men and -1.0% for women). Velocity at P 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 tended to decline more in women than in men (p = 0.065). To conclude, both knee extensor P 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.
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http://dx.doi.org/10.1016/j.exger.2018.06.021DOI Listing
September 2018

Age-related decline in leg-extensor power development in single- versus multi-joint movements.

Exp Gerontol 2018 09 30;110:98-104. Epub 2018 May 30.

KU Leuven, Department of Movement Sciences, Physical Activity, Sports and Health Research Group, Belgium.

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http://dx.doi.org/10.1016/j.exger.2018.05.019DOI Listing
September 2018

Test-retest reliability of knee extensor rate of velocity and power development in older adults using the isotonic mode on a Biodex System 3 dynamometer.

PLoS One 2018 3;13(5):e0196838. Epub 2018 May 3.

Department of Kinesiology, Physical Activity, Sports and Health Research Group, KU Leuven, Leuven, Belgium.

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.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0196838PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5933798PMC
August 2018

Weight bearing exercise can elicit similar peak muscle activation as medium-high intensity resistance exercise in elderly women.

Eur J Appl Physiol 2018 Mar 30;118(3):531-541. Epub 2017 Dec 30.

Department of Movement Sciences, Physical Activity, Sports and Health Research Group, KU Leuven, Tervuursevest 101, 3001, Leuven, Belgium.

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.
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http://dx.doi.org/10.1007/s00421-017-3793-8DOI Listing
March 2018

Age-related differences in rate of power development exceed differences in peak power.

Exp Gerontol 2018 01 16;101:95-100. Epub 2017 Nov 16.

KU Leuven, Department of Movement Sciences, Physical Activity, Sports and Health Research Group, Belgium.

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http://dx.doi.org/10.1016/j.exger.2017.11.009DOI Listing
January 2018

Enhancing Physical Activity as Lifestyle Behavior in Older Persons: The Rome Statement.

J Aging Phys Act 2018 04 12;26(2):345-351. Epub 2018 Apr 12.

Within the context of a globally aging population and associated age-related changes to social relationships and individual psycho-physiology, a coalition of mostly European Union (EU) organizations concerned with physical activity in older persons was formed in 2013. The coalition examined worldwide decreases in physical activity among older adults, and the resulting negative effects on health and function for those individuals. After holding expert panel meetings, the coalition developed recommendations about how to address macro- and microlevel changes to increase and sustain physical activity among older populations across Europe. The recommendations were then compiled into a consensus document called "the Rome Statement", aimed at older adults, policy makers, researchers, and private and public professionals. This article presents the Rome Statement and its recommendations, and discusses how the statement can be broadly disseminated, considered, and implemented.
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http://dx.doi.org/10.1123/japa.2017-0001DOI Listing
April 2018

Training load does not affect detraining's effect on muscle volume, muscle strength and functional capacity among older adults.

Exp Gerontol 2017 11 1;98:30-37. Epub 2017 Aug 1.

KU Leuven, Department of Kinesiology, Physical Activity, Sports and Health Research Group, Belgium.

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 24weeks of detraining that followed 12weeks of high- and low-load resistance exercise in older adults. Fifty-six older adults (68.0±5.0years) 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 24weeks 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 24weeks 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.
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http://dx.doi.org/10.1016/j.exger.2017.07.017DOI Listing
November 2017

Effect of a prehop on the muscle-tendon interaction during vertical jumps.

J Appl Physiol (1985) 2018 05 3;124(5):1203-1211. Epub 2017 Aug 3.

Human Movement Biomechanics Research Group, Department of Kinesiology, KU Leuven-University of Leuven, Leuven , Belgium.

Many movements use stretch-shortening cycles of a muscle-tendon unit (MTU) for storing and releasing elastic energy. The required stretching of medial gastrocnemius (MG) tendinous tissue during jumps, however, requires large length changes of the muscle fascicles because of the lack of MTU length changes. This has a negative impact on the force-generating capacity of the muscle fascicles. The purpose of this study was to induce a MG MTU stretch before shortening by adding a prehop to the squat jump. Eleven well-trained athletes specialized in jumping performed a prehop squat jump (PHSJ) and a standard squat jump (SSJ). Kinematic data were collected using a 3D motion capture system and were used in a musculoskeletal model to calculate MTU lengths. B-mode ultrasonography of the MG was used to measure fascicle length and pennation angle during the jumps. By combining the muscle-tendon unit lengths, fascicle lengths, and pennation angles, the stretch and recoil of the series elastic element of MG were calculated using a simple geometric muscle-tendon model. Our results show less length changes of the muscle fascicles during the upward motion and lower maximal shortening velocities, increasing the moment-generating capacity of the plantar flexors, reflected in the higher ankle joint moment in the PHSJ compared with the SSJ. Although muscle-tendon interaction during the PHSJ was more optimal, athletes were not able to increase their jump height compared with the SSJ. NEW & NOTEWORTHY This is the first study that aimed to improve the muscle-tendon interaction in squat jumping. We effectively introduced a stretch to the medial gastrocnemius muscle-tendon unit resulting in lower maximal shortening velocities and thus an increase in the plantar flexor force-generating capacity, reflected in the higher ankle joint moment in the prehop squat jump compared with the standard squat jump. Here, we demonstrate an effective method for mechanical optimization of the muscle-tendon interaction in the medial gastrocnemius during squat jumping.
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http://dx.doi.org/10.1152/japplphysiol.00462.2017DOI Listing
May 2018

Sex difference in the heat shock response to high external load resistance training in older humans.

Exp Gerontol 2017 07 19;93:46-53. Epub 2017 Apr 19.

Gerontology Department, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, B-1090 Brussels, Belgium.; Frailty in Aging Research (FRIA) Group, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, B-1090 Brussels, Belgium.; Department of Geriatrics, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, B-1090 Brussels, Belgium.. Electronic address:

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±5years) volunteers were randomized to 12weeks 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 12weeks for determination of eHsp70. Mid-thigh muscle volume (computed tomography), muscle strength (1RM & Biodex dynamometer) and physical functioning (including 6min 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.
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http://dx.doi.org/10.1016/j.exger.2017.04.005DOI Listing
July 2017

Joint power generation differentiates young and adult sprinters during the transition from block start into acceleration: a cross-sectional study.

Sports Biomech 2017 Nov 29;16(4):452-462. Epub 2017 Mar 29.

b Department of Kinesiology, Research unit of Human Movement Biomechanics , KU Leuven , Heverlee , Belgium.

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.
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http://dx.doi.org/10.1080/14763141.2016.1234639DOI Listing
November 2017

Effects of resistance training at different loads on inflammatory markers in young adults.

Eur J Appl Physiol 2017 Mar 6;117(3):511-519. Epub 2017 Feb 6.

Gerontology Department, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090, Brussels, Belgium.

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 HI (n = 12, 1 × 10-12 repetitions at 80% 1RM), LO (n = 12, 1 × 10-12 repetitions at 40% 1RM), or LO (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 HI (p = 0.022) and LO (p = 0.024); and IL-6 decreased significantly in LO (p = 0.009) and LO (p = 0.013). No significant overall time effect was observed for sTNFR1 and IL-1RA; however, in HI sTNFR1 (p = 0.031) and IL-1RA (p = 0.014) increased significantly, but remained unchanged in LO 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.
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http://dx.doi.org/10.1007/s00421-017-3548-6DOI Listing
March 2017

Ergometer-cycling with strict versus minimal contact supervision among the oldest adults: A cluster-randomised controlled trial.

Arch Gerontol Geriatr 2017 May - Jun;70:112-122. Epub 2017 Jan 19.

KU Leuven, Department of Kinesiology, Physical Activity, Sports and Health Research Group, Tervuursevest 101, 3001 Leuven, Belgium.

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±5.9years) 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.
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http://dx.doi.org/10.1016/j.archger.2017.01.010DOI Listing
July 2017

Load-Specific Inflammation Mediating Effects of Resistance Training in Older Persons.

J Am Med Dir Assoc 2016 06 24;17(6):547-52. Epub 2016 Mar 24.

Department of Gerontology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium; Frailty in Aging Research (FRIA) Group, Vrije Universiteit Brussel, Brussels, Belgium; Department of Geriatrics, Universitair Ziekenhuis Brussel, Brussels, Belgium. Electronic address:

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.
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http://dx.doi.org/10.1016/j.jamda.2016.02.010DOI Listing
June 2016

Age-related decline in muscle mass and muscle function in Flemish Caucasians: a 10-year follow-up.

Age (Dordr) 2016 Apr 9;38(2):36. Epub 2016 Mar 9.

Faculty of Kinesiology and Rehabilitation Sciences, Department of Kinesiology, Physical Activity, Sports and Health Research Group, KU Leuven, Tervuursevest 101, 3001, Leuven, Belgium.

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 (S 20 %), 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 S 20 % 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 (E sport). In conclusion, strength performance was not associated with E sport in this study, but protein intake was associated with isometric strength in men, and with ballistic and isokinetic strength in women. Changes in S 20 % 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 E sport.
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http://dx.doi.org/10.1007/s11357-016-9900-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5005902PMC
April 2016

Dose-and gender-specific effects of resistance training on circulating levels of brain derived neurotrophic factor (BDNF) in community-dwelling older adults.

Exp Gerontol 2015 Oct 18;70:144-9. Epub 2015 Aug 18.

Gerontology (GERO) Department, VrijeUniversiteitBrussel, Laarbeeklaan 103, B-1090 Brussels, Belgium; Frailty in Aging Research (FRIA) Department, VrijeUniversiteitBrussel, Laarbeeklaan 103, B-1090 Brussels, Belgium; Department of Geriatrics, UniversitairZiekenhuis Brussel, Laarbeeklaan 101, B-1090 Brussels, Belgium. Electronic address:

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% 1 RM), low-resistance (LOW, 9 Males, 10 Females, 1 × 80-100 repetitions at 20% 1 RM), or mixed low-resistance (LOW+, 9 Males, 10 Females, 1 × 60 repetitions at 20% 1 RM followed by 1 × 10-20 repetitions at 40% 1 RM). 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.
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http://dx.doi.org/10.1016/j.exger.2015.08.004DOI Listing
October 2015

Low- and High-Resistance Exercise: Long-Term Adherence and Motivation among Older Adults.

Gerontology 2015 12;61(6):551-60. Epub 2015 May 12.

Physical Activity, Sports and Health Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium.

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.
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http://dx.doi.org/10.1159/000381473DOI Listing
August 2016

Effects of a Six-Month Local Vibration Training on Bone Density, Muscle Strength, Muscle Mass, and Physical Performance in Postmenopausal Women.

J Strength Cond Res 2015 Sep;29(9):2613-22

1Department of Rehabilitation Science, KU Leuven-University of Leuven, Musculoskeletal Rehabilitation Research Centre, Leuven, Belgium; 2Department of Biomedical Kinesiology, KU Leuven-University of Leuven, Research Centre for Exercise and Health, Leuven, Belgium; 3Department of Experimental Medicine, KU Leuven-University of Leuven, UZ Leuven, Leuven, Belgium; and 4Thomas More, Campus Geel, Life Sciences, Mobilab, Geel, Belgium.

The aim of the study was to investigate the effect of 6 months' local vibration training on bone mineral density (BMD), muscle strength, muscle mass, and physical performance in postmenopausal women (66-88 years). The study was organized as a randomized controlled trial for postmenopausal women who lived in daily care service flats and rest homes. Thirty-five postmenopausal women were randomly assigned to either a vibration (n = 17) or a control group (n = 18). The vibration group received 6-month local vibration treatment with frequency between 30 and 45 Hz and acceleration between 1.71 and 3.58g. The vibration was applied on the midthigh and around the hip in supine-lying position once per day, 5 d·wk. The participants of the control group continued their usual activities and were not involved in any additional training program. The primary outcome variables were the isometric and dynamic quadriceps muscle strength and the BMD of the hip. We assessed the muscle mass of the quadriceps and physical performance. Additionally, the feasibility, side effects, and compliance were evaluated after 6 months of local vibration training. Overall, the results showed a net benefit of 13.84% in isometric muscle strength at 60° knee angle in favor of the vibration group compared with controls (p < 0.01). No changes in BMD, muscle mass, or physical performance were found in both groups (p > 0.05). Six months of local vibration training improved some aspects of muscle strength but had no effect on BMD, muscle mass, and physical performance in postmenopausal women. The specific vibration protocol used in this study can be considered as safe and suitable for a local vibration training program.
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http://dx.doi.org/10.1519/JSC.0000000000000895DOI Listing
September 2015
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