13 research outputs found
Effect van vibratie training op spierkracht, prestatie en snelheidsgerelateerde mechanische spierkarakteristieken
No full textDe resultaten van de studies van dit doctoraatsproject tonen aan dat de vibratiestimulus tijdens whole body vibration (WBV) een duidelijke meerwaarde heeft bovenop de oefeningen uitgevoerd op het WBV platform om spierkracht te verbeteren (geen placebo effect). WBV training is een efficiënte trainingsmethode om de kracht van de knie-extensoren en de sprongkracht te verbeteren in specifieke groepen. Voornamelijk mensen met een lage initiële spierkracht ten gevolgen van onvoldoende training of het verouderingsproces kunnen voordeel halen uit WBV training. Vooral zwakke mensen, zoals ongetrainden en ouderen, die zich niet aangetrokken voelen tot klassieke krachttraining kunnen baat hebben bij WBV training. Een optimale trainingsintensiteit en trainingsvolume van het WBV trainingsprogramma, voornamelijk een voldoende totale duur van de vibratie in één trainingssessie, zijn cruciaal om een voldoende overload te creëren voor het induceren van neuromusculaire adaptaties. De resultaten van de studies tonen aan dat 12 weken trilplaat training (3x/week, 35-40 Hz, 1.72.5 mm, max. 30 minuten) een efficiënt en haalbaar alternatief is om de kracht van de beenspieren en de sprongkracht te verbeteren bij ongetrainde jonge mensen en 60-plussers. De grootte orde van de krachtwinst is vergelijkbaar met de effecten na het volgen van een klassiek krachttrainingsprogramma aan matige intensiteit in de fitness zaal. Toch kan men niet stellen dat trilplaat training efficiënter is om de explosiviteit te verbeteren in vergelijking met klassieke krachttraining. In tegenstelling tot bij oudere dames is bovendien aangetoond dat 24 weken trilplaat training bij ongetrainde jonge dames niet leidt tot een daling in percentage lichaamsvet en onderhuids vet. Wel gaat de krachtwinst gepaard met een kleine toename in spiermassa. In een studie bij spurters met een specifiek trilplaat trainingsprogramma toegevoegd aan het klassieke trainingsprogramma konden we geen meerwaarde op krachtsnelheid en spurtprestatie vinden. Tot slot konden we in een fundamentele studie gebruik makend van lokale spiervibratie niet aantonen dat vibratie in staat is om specifieke snelheidsgerelateerde trainingseffecten te induceren.Als conclusie kan gesteld worden dat tot nog toe geen evidentie kon gevonden worden dat vibratietraining werkt bij atleten en leidt tot specifieke snelheidsgerelateerde aanpassingen in de spier. Wel is duidelijk aangetoond dat trilplaat training een efficiënte alternatieve trainingsmethode is voor mensen met een zwakke spierkracht ten gevolge van te weinig lichaamsbeweging of leeftijdsgerelateerde daling in spierkracht. De grootte orde van de trainingseffecten na vibratietraining zijn vergelijkbaar met die van klassieke krachttraining.status: Publishe
Multivariate genetic analysis of maximal isometric muscle force at different elbow angles
No full text Thomis, Martine A., Marc Van Leemputte, Hermine H. Maes, Cameron J. R. Blimkie, Albrecht L. Claessens, Guy Marchal, Eustachius Willems, Robert F. Vlietinck, and Gaston P. Beunen. Multivariate genetic analysis of maximal isometric muscle force at different elbow angles. J. Appl. Physiol. 82(3): 959–967, 1997.—The maximal isometric moment at five different elbow joint angles was measured in 25 monozygotic and 16 dizygotic male adult twin pairs (22.4 ± 3.7 yr). Genetic model fitting was used to quantify the genetic and environmental contributions to individual differences in isometric strength. Additive genetic factors explained 66–78% of the variance in maximal torque at 170–140–110 and 80° flexion (extension = 180°). At 50° flexion, common and subject-specific environmental factors contributed equally to the variation. The contribution of unique environmental factors concurs with the level of variability in muscle activation and (dis)-comfort of torque production in the specific angle. The relative contribution of lever arm and force-length relationship in torque varies according to the angle. Because these factors might be genetic, this variability is reflected in the genetic contribution at the extreme angles of 170 and 50°. Multivariate analyses suggested a general set of genes that control muscle area and isometric strength, together with a more specific strength factor. Genetic correlations were high (0.82–0.99). Genes responsible for arm-segment lengths did not contribute to muscle area nor to isometric strength. </jats:p
Protective role of alpha-actinin-3 in the response to an acute eccentric exercise bout
No full textVincent B, Windelinckx A, Nielens H, Ramaekers M, Van Leemputte M, Hespel P, Thomis MA. Protective role of alpha-actinin-3 in the response to an acute eccentric exercise bout. J Appl Physiol 109: 564-573, 2010. First published May 27, 2010; doi: 10.1152/japplphysiol.01007.2009.-The ACTN3 gene encodes for the alpha-actinin-3 protein, which has an important structural function in the Z line of the sarcomere in fast muscle fibers. A premature stop codon (R577X) polymorphism in the ACTN3 gene causes a complete loss of the protein in XX homozygotes. This study investigates a possible role for the alpha-actinin-3 protein in protecting the fast fiber from eccentric damage and studies repair mechanisms after a single eccentric exercise bout. Nineteen healthy young men (10 XX, 9 RR) performed 4 series of 20 maximal eccentric knee extensions with both legs. Blood (creatine kinase; CK) and muscle biopsy samples were taken to study differential expression of several anabolic (MyoD1, myogenin, MRF4, Myf5, IGF-1), catabolic (myostatin, MAFbx, and MURF-1), and contraction-induced muscle damage marker genes [cysteine-and glycine-rich protein 3 (CSRP3), CARP, HSP70, and IL-6] as well as a calcineurin signaling pathway marker (RCAN1). Baseline mRNA content of CSRP3 and MyoD1 was 49 +/- 12 and 67 +/- 25% higher in the XX compared with the RR group (P = 0.01-0.045). However, satellite cell number was not different between XX and RR individuals. After eccentric exercise, XX individuals tended to have higher serum CK activity (P = 0.10) and had higher pain scores than RR individuals. However, CSRP3 (P = 0.058) and MyoD1 (P = 0.08) mRNA expression tended to be higher after training in RR individuals compared with XX alpha-actinin-3-deficient subjects. This study suggests a protective role of alpha-actinin-3 protein in muscle damage after eccentric training and an improved stress-sensor signaling, although effects are small
EFFECT OF AN EXPERIMENTAL PEDAL ON MAXIMAL POWER OUTPUT AND PEDALLING TECHNIQUE IN TRAINED CYCLISTS
No full textThe aim of the present study is to evaluate the effect of an experimental pedal system (EP) on maximal isokinetic power generation and pedalling technique during cycling of well trained cyclists. Compared to habitual pedals (HP), in EP the foot contact area with respect to the pedal axis was located more inferior and anterior, which affects the distance between the crank axis and the point of force application (Functional crankarm length, Fcal) during the pedalling cycle. Since Martin (2001) showed enhanced propulsive torque in the downstroke of the pedalling cycle with longer crankarm length, we hypothesized EP to improve maximal isokinetic power output (P) and that the improvement is related to Fcal
The effect of muscle length on force depression after active shortening in soleus muscle of mice
No full textAge-related decline in leg-extensor power development in single- versus multi-joint movements
No full text© 2018 Elsevier Inc. 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.status: Publishe
Physiological Adaptations to Hypoxic vs. Normoxic Training during Intermittent Living High
No full textIn the setting of “living high,” it is unclear whether high-intensity interval training (HIIT) should be performed “low” or “high” to stimulate muscular and performance adaptations. Therefore, 10 physically active males participated in a 5-week “live high-train low or high” program (TR), whilst eight subjects were not engaged in any altitude or training intervention (CON). Five days per week (~15.5 h per day), TR was exposed to normobaric hypoxia simulating progressively increasing altitude of ~2,000–3,250 m. Three times per week, TR performed HIIT, administered as unilateral knee-extension training, with one leg in normobaric hypoxia (~4,300 m; TRHYP) and with the other leg in normoxia (TRNOR). “Living high” elicited a consistent elevation in serum erythropoietin concentrations which adequately predicted the increase in hemoglobin mass (r = 0.78, P < 0.05; TR: +2.6%, P < 0.05; CON: −0.7%, P > 0.05). Muscle oxygenation during training was lower in TRHYP vs. TRNOR (P < 0.05). Muscle homogenate buffering capacity and pH-regulating protein abundance were similar between pretest and posttest. Oscillations in muscle blood volume during repeated sprints, as estimated by oscillations in NIRS-derived tHb, increased from pretest to posttest in TRHYP (~80%, P < 0.01) but not in TRNOR (~50%, P = 0.08). Muscle capillarity (~15%) as well as repeated-sprint ability (~8%) and 3-min maximal performance (~10–15%) increased similarly in both legs (P < 0.05). Maximal isometric strength increased in TRHYP (~8%, P < 0.05) but not in TRNOR (~4%, P > 0.05). In conclusion, muscular and performance adaptations were largely similar following normoxic vs. hypoxic HIIT. However, hypoxic HIIT stimulated adaptations in isometric strength and muscle perfusion during intermittent sprinting
Impact of Oral Creatine Supplementation on Muscle Performance During Training and Rehabilitation
No full textHistory-dependent force, angular velocity and muscular endurance in ACTN3 genotypes
No full textThis study aimed at determining the influence of the ACTN3 R577X polymorphism on muscle strength and muscle endurance in non-athletic young men
Hand strength and fatigue in patients with hereditary motor and sensory neuropathy (types I and II)
No full textObjectives: To compare maximal isometric hand strength and fatigue between subjects with hereditary motor and sensory neuropathy (HMSN) and healthy controls and to test the reproducibility of handgrip strength (peak force of handgrip [PFgrip]) and fatigue. Design: PFgrip and the decline in PFgrip during 3 sets of 15 contractions were compared. Setting: University hospital in The Netherlands. Participants: Twenty subjects with HMSN and 20 age- and sex-matched healthy controls; 15 healthy subjects for the reproducibility part of the study. Interventions: Not applicable. Main Outcome Measures: PFgrip and the decline in PFgrip were compared by using a digital handgrip dynamometer. Two-point and lateral pinch measurements of subjects with HMSN were standardized against reference values. Reproducibility measurements were performed on 15 healthy subjects on 2 separate occasions within a 1-week interval. Results: PFgrip was significantly lower in the HMSN subjects compared with controls (P <.05). Pinch measurements also showed a large variance from average normal performance. No significant difference was found in the decline in percentage of PFgrip. Reproducibility was excellent for PFgrip (intraclass correlation coefficient [ICC]=.98; 95% confidence interval [CI],.95-99) but poor for fatigue (ICC=.62; 95% CI,.20-85). Conclusion: PFgrip and 2-point and lateral pinch in HMSN subjects were significantly reduced compared with healthy controls. Our findings indicated that the rate of decline of PFgrip during effort does not vary between group
