TY - JOUR AU - Váczi, Márk AU - Nagy, Szilvia Anett AU - Kőszegi, Tamás AU - Ambrus, Mira AU - Bogner, Péter AU - Perlaki, Gábor AU - Orsi, Gergely AU - Toth, K AU - Hortobágyi, Tibor TI - Mechanical, hormonal, and hypertrophic adaptations to 10weeks of eccentric and stretch-shortening cycle exercise training in old males. JF - EXPERIMENTAL GERONTOLOGY J2 - EXP GERONTOL VL - 58 PY - 2014 SP - 69 EP - 77 PG - 9 SN - 0531-5565 DO - 10.1016/j.exger.2014.07.013 UR - https://m2.mtmt.hu/api/publication/2713730 ID - 2713730 AB - The growth promoting effects of eccentric (ECC) contractions are well documented but they are unknown if the rate of stretch per se plays a role in such muscular responses in healthy aging human skeletal muscle. We tested the hypothesis that exercise training of the quadriceps muscle with low rate ECC and high rate ECC contractions in the form of stretch-shortening cycles (SSCs) but at equal total mechanical work would produce rate-specific adaptations in healthy old males age 60-70. Both training programs produced similar improvements in maximal voluntary isometric (6%) and ECC torque (23%) and stretch-shortening cycle function (reduced contraction duration [24%] and enhanced elastic energy storage [12%]) (p<0.05). The rate of torque development increased 30% only after SSC exercise (p<0.05). Resting testosterone and cortisol levels were unchanged but after each program the acute exercise-induced cortisol levels were 12-15% lower (p<0.05). Both programs increased quadriceps size at 2.5% (p<0.05). It is concluded that both ECC and SSC exercise training produces favorable adaptations in healthy old males' quadriceps muscle. Although the rate of muscle tension during the SSC vs. ECC contractions was about 4-fold greater, the total mechanical work seems to regulate the hypetrophic, hormonal, and most of the mechanical adaptations. However, SSC exercise was uniquely effective in improving a key deficiency of aging muscle, i.e., its ability to produce force rapidly. LA - English DB - MTMT ER - TY - JOUR AU - Váczi, Márk AU - Rácz, Levente AU - Hortobágyi, Tibor AU - Tihanyi, József TI - Dynamic contractility and efficiency impairments in stretch-shortening cycle are stretch-load dependent after training-induced muscle damage. JF - JOURNAL OF STRENGTH AND CONDITIONING RESEARCH J2 - J STRENGTH CONDIT RES VL - 27 PY - 2013 IS - 8 SP - 2171 EP - 2179 PG - 9 SN - 1064-8011 DO - 10.1519/JSC.0b013e31827da32c UR - https://m2.mtmt.hu/api/publication/2192369 ID - 2192369 AB - ABSTRACT: To determine the acute task- and stretch load-dependency of neuromuscular impairments after muscle-damaging exercise, we examined the magnitude of strength deficits in isometric and stretch-shortening cycle (SSC) contractions following a single bout of exercise. Ten trained males performed 90 unilateral isokinetic eccentric-concentric knee extensions on a dynamometer. Plasma creatine kinase activity, muscle soreness, maximal isometric torque, short-range stiffness and peak torque in the eccentric phase of the SSC contraction at three stretch loads (120, 150 and 180 Joule) were determined in the quadriceps before, and 24 hours after exercise. During SSC, positive mechanical work and efficiency were also calculated. Creatine kinase and soreness increased at 24h (p < 0.05). In each of the three stretch-load conditions, muscle damage affected short-range stiffness less than isometric and peak SSC torque (p < 0.05), providing evidence for a selective impairment in contractile function after muscle damage. With greater SSC stretch-load peak SSC torque deficit increased linearly, while short-range stiffness deficit was unaffected. Efficiency declined only at the 180 Joule condition (p < 0.05) as a result of decreased positive work (p < 0.05). It was concluded that intense exercise produced microtrauma in the muscle, as well as a selective loss of force generating capacity, which suggests greater damage to the contractile machinery. Practitioners may expect greater acute impairment of force generation in movements that use large loads in their daily training drills. However, altered knee flexion strategy during SSC may compensate for the force deficit, preserving mechanical efficiency at smaller stretch-loads. LA - English DB - MTMT ER - TY - JOUR AU - Váczi, Márk AU - Tihanyi, József AU - Hortobágyi, Tibor AU - Rácz, Levente AU - Csende, Zsolt AU - Costa, Andreas AU - Pucsok, József TI - Mechanical, Biochemical, and Electromyographic Responses to Short-term Eccentric-Concentric Knee Extensor Training in Humans JF - JOURNAL OF STRENGTH AND CONDITIONING RESEARCH J2 - J STRENGTH CONDIT RES VL - 25 PY - 2011 IS - 4 SP - 922 EP - 932 PG - 11 SN - 1064-8011 DO - 10.1519/JSC.0b013e3181c1fa47 UR - https://m2.mtmt.hu/api/publication/1881645 ID - 1881645 N1 - Accession Number: 60170223; Author: VÁCZI, MÁRK: 1 email: mvaczi@freemail.hu. Author: TIHANYI, JÓZSEF: 1 Author: HORTOBÁGYI, TIBOR: 2 Author: RÁCZ, LEVENTE: 1 Author: CSENDÉ, ZSOLT: 1 Author: COSTA, ANDREAS: 1 Author: PUCSOK, JÓZSEF: 3 ; Author Affiliation: 1 Biomechanics Laboratory, Department of Biomechanics, Semmelweis University, Faculty of Physical Education and Sport Science, Budapest, Hungary.: 2 Biomechanics Laboratory, East Carolina University, Greenville, North Carolina.: 3 Research Institute, National Institute for Sport Mediane, Budapest, Hungary.; No. of Pages: 11; Language: English; Publication Type: Journal Article; Update Code: 20110504 DP: EBSCOhost DB: s3h AB - The article describes a study that examined the effects that short-term eccentric-concentric knee extensor training in humans had on their biomechanical and biochemical variables, muscle soreness, and electromyographic activity. It was found that the training caused immediate reductions in maximal voluntary force. LA - English DB - MTMT ER -