Search results for "isometric"
showing 10 items of 535 documents
Twitch interpolation during equal-intensity voluntary and electrically-evoked isometric contractions of the quadriceps muscle
2005
It has been suggested that, during contractions triggered by electrical stimulation, motor units are recruited in a reversed sequence compared to voluntary contraction. The classic view is that lar...
Microvascular blood flow changes of the abductor pollicis brevi muscle during sustained static exercise
2020
ABSTRACTA practical assessment of the health of the palm muscle, abductor pollicis brevis (APB), is important for diagnosis of different conditions. Here we have developed a protocol and a probe to utilize diffuse correlation spectroscopy (DCS) to characterize microvascular blood flow changes in the APB during and after sustained isometric exercise, during and after thumb abduction at at 55% of maximum voluntary contraction (MVC). Blood flow in the APB decreased during exercise in the subjects (n=13) with high MVC (n=7) and stayed constant in the ones with low MVC (n=6) suggesting that the mechanical occlusion due to increased intramuscular pressure exceeded the vasodilation elicited by the…
Muscle strength before and mortality after a bone fracture in older people
2002
We studied whether muscle strength measured before a bone fracture predicts mortality following the fracture. The participants were a sub-cohort of 82 people of a total of 493 Evergreen project participants initially aged 75- and 80 years, who had participated in knee extension strength tests as part of the baseline examinations, and who subsequently suffered at least one bone fracture. Maximal isometric knee extension strength was measured at baseline using an adjustable dynamometer chair. Fracture surveillance was carried out from patient records for 5 years, and mortality surveillance from population register for 10 years after baseline examinations. Average time till a fracture occurred…
The Stretch-Shortening Cycle
2006
Neuromuscular fatigue has traditionally been examined using isolated forms of either isometric, concentric or eccentric actions. However, none of these actions are naturally occurring in human (or animal) ground locomotion. The basic muscle function is defined as the stretch-shortening cycle (SSC), where the preactivated muscle is first stretched (eccentric action) and then followed by the shortening (concentric) action. As the SSC taxes the skeletal muscles very strongly mechanically, its influence on the reflex activation becomes apparent and very different from the isolated forms of muscle actions mentioned above. The ground contact phases of running, jumping and hopping etc. are example…
Resistance exercise-induced hormonal response under the influence of delayed onset muscle soreness in men and boys
2010
It was hypothesized that exercise-induced muscle damage (EIMD)-related alterations in hormonal responses could be observed if a second exercise bout is performed soon after an identical unaccustomed bout leading to delayed onset muscle soreness (DOMS). Eight men (31 ± 7 years) and eight boys (14 ± 0 years) performed two exercise bouts (E1 and E2, with 48 h rest in between) consisting of three sets of bilateral knee extensions until exhaustion with 40% load. No differences between the groups or bouts were observed in the number of repetitions performed and maximal isometric force decline, or between groups in serum creatine kinase activity and DOMS. Decreased peak epinephrine (EPI) (-38%), g…
Physical activity compensates for increased mortality risk among older people with poor muscle strength
2006
The aim of the study was to determine whether habitual physical activity can compensate for the increased mortality risk among older people with poor muscle strength. Mortality was followed up for 10 years after laboratory examination in 558 community dwelling 75- and 80-year-old men and women. Maximal isometric strength of five muscle groups was measured and tertile cut-off points were used to categorize participants. Participants, who reported moderate physical activity for at least 4 h a week, were categorized as physically active and the others as sedentary. High muscle strength and physical activity both protected from mortality, but their effect was not additive. Within each muscle st…
Effects of prolonged and maintenance strength training on force production, walking, and balance in aging women and men
2012
To examine effects of 21-week twice/week strength training (ST) period followed by an additional 21-week twice or once/week ST period on force production, walking and balance in aging people. Seventy-two women (58 ± 7 years; W) and 63 (58 ± 6 years) men (M) were randomized for the first 21-week ST period: STW and STM, control (C) CW and CM. Training participants were randomized for the second 21-week ST period: once/week STWx1 and STMx1, twice/week STWx2 and STMx2. LegPress, isometric leg extension rate of force development (RFD), walking time, and balance. First 21-week ST period: leg press, RFD, balance, and walking improved significantly in STW and STM. Second 21-week ST period: leg pres…
Maximal isometric muscle strength and anthropometry in 75-year-old men and women in three Nordic localities
2007
Isometric maximal strength of hand grip, elbow flexion, knee extension, trunk extension and trunk flexion was studied in representative samples of 75-year-old residents of 3 Nordic localities: Glostrup in Denmark, Gothenburg in Sweden and Jyvaskyla in Finland. The study forms a part of a wider comparative research project analyzing the functional capacity and health of 75-year-olds in these towns. The strength measurements were carried out using standardized techniques and identical dynamometers. The results showed that the strength values of the limb muscles were significantly lower among the 75-year-olds in Jyvaskyla, both in absolute values and in relative units (N/kg body mass). For the…
Acute neuromuscular and hormonal responses during contrast loading: Effect of 11 weeks of contrast training
2009
The purpose of this study was to assess (1) acute neuromuscular and endocrine responses during a contrast loading protocol and (2) how these acute responses are possibly influenced by 11 weeks of contrast training. Contrast loading tests consisting of 4 sets of 80% 1 RM back squat and 4 sets of squat jump (SJ) were performed before and after training. Bilateral isometric leg extension (LE) assessed the impact of loading on isometric variables pre-, mid-, and post-loading. Potentiated SJ performance was observed in set 2 (4.6%, P<0.05), before training only. Greater indications of fatigue were observed in SJ, isometric force, and vastus lateralis (VL) activation after training (P<0.05). Trai…
Strength and power changes of the human plantar flexors and knee extensors in response to resistance training in old age
2002
Aim: The aim of the present study was to assess and compare the improvements of muscle strength and power induced by a 16-week resistive programme in a population of 16 older men aged 65-81 years. Methods: Training was performed three times per week at an intensity of 80% of one repetition maximum (1RM) and consisted of both calf raise and leg press exercises. Before-, during- and after-training, maximum isometric and isokinetic torques, maximum power, 1RM, muscle cross-sectional area (CSA) and electromyographic activity (EMG) of the plantar flexors (PF) and knee extensors (KE) were examined. Results: For the KE and PF, respectively, training resulted in a 29.9 ± 4.4% (mean ± SE) and 21.6 ±…