Isokinetic dynamometry is the gold standard for testing maximal strength in elite sport and rehabilitation settings. To be clinically useful, such tests should be valid and reliable. Despite some ...evidence regarding the relative test vs retest reliability of knee dynamometry, there is still a paucity of research regarding the absolute reliability parameters. The purpose of this study was to assess the absolute and relative intra-device reproducibility of isokinetic knee flexion and extension using the novel SMM iMoment dynamometer. A total of 19 participants (13 males and 6 females, aged 24 (2) years, height 178 (9) cm and weight 76 (11) kg) performed two identical knee isokinetic tests with at least a week of rest between measurements. Peak torque of knee extension and flexion were determined at 60°/s. Moderate (0.892) to excellent (0.988) relative reliability using the intraclass correlation coefficient (ICC) was obtained for peak knee torque. Absolute reliability assessed with a standard error of measurement (SEM %) was low, ranging from 2.54% to 6.93%, whereas the smallest real difference (SRD %) was moderate, ranging from 7.04% to 19.22%. Furthermore, there were no significant correlations between means and differences of two measurements, and Bland-Altman plots also showed no signs of heteroscedasticity. Our measurement protocol established the moderate to excellent reliability of the novel SMM iMoment isokinetic dynamometer. Therefore, this dynamometer can be applied in sport rehabilitation settings to measure maximal knee strength.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Resistance training may be associated with unfavorable cardiovascular responses (such as hemodynamic alterations, anginal symptoms or ventricular arrhythmias). In healthy adults, blood ...flow-restricted (BFR) resistance training improves muscle strength and hypertrophy improvements at lower loads with minimal systemic cardiovascular adverse responses. The aim of this study was to assess the safety and efficacy of BFR resistance training in patients with coronary artery disease (CAD) compared to usual care. Patients with stable CAD were randomized to either 8 weeks of supervised biweekly BFR resistance training (30-40% 1RM unilateral knee extension) or usual exercise routine. At baseline and after 8 weeks, patients underwent 1-RM knee extension tests, ultrasonographic appraisal of
(VL) muscle diameter and of systemic (brachial artery) flow-mediated dilation, and determination of markers of inflammation (CD40 ligand and tumor necrosis factor alfa), and fasting glucose and insulin levels for homeostatic model assessment (HOMA). A total of 24 patients 12 per group, mean age 60 ± 2 years, 6 (25%) women were included. No training-related adverse events were recorded. At baseline groups significantly differ in age (mean difference: 8.7 years,
< 0.001), systolic blood pressure (mean difference: 12.17 mmHg,
= 0.024) and in metabolic control insulin (
= 0.014) and HOMA IR (
= 0.014). BFR-resistance training significantly increased muscle strength (1-RM, +8.96 kg,
< 0.001), and decreased systolic blood pressure (-6.77 mmHg;
= 0.030), whereas VL diameter (+0.09 cm,
= 0.096), brachial artery flow-mediated vasodilation (+1.55%;
= 0.079) and insulin sensitivity (HOMA IR change of 1.15,
= 0.079) did not improve significantly. Blood flow restricted resistance training is safe and associated with significant improvements in muscle strength, and may be therefore provided as an additional exercise option to aerobic exercise to improve skeletal muscle functioning in patients with CAD. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03087292.
Review of Painful Foot and Ankle Conditions Kambic, Tim; Hadžic, Vedran; Khan, Karim M
JAMA : the journal of the American Medical Association,
03/2024, Letnik:
331, Številka:
12
Journal Article
Resistance training (RT) is recommended to counteract the deleterious effects of sarcopenia on muscle mass and function. 1–3 The evidence about optimal RT scheme (training intensity, volume, rest, ...and so on) for optimal muscle outcomes in older individuals with and without sarcopenia as assessed by novel and recently recommended measurement techniques (magnetic resonance imaging, computed tomography, bioimpedance, dual-energy X-ray absorptiometry) 1,2 remains limited. ...to recent RT guidelines in healthy older adults, 3 the authors compared only the effects of LL-RT 40% of one repetition maximum (1-RM) and ML-RT (60% of 1-RM) 4; both of them may present a suboptimal stimulus to induce muscle hypertrophy and strength gains. 3,5 Current recommendations are also supported by the previous two meta-analysis showing the safety and superiority of high-load (HL-RT) over ML-RT and LL-RT on muscle strength, and similar effects on muscle hypertrophy in healthy young and older adults. 6,7 Furthermore, the cumulative training load should have been balanced between LL-RT and ML-RT groups by a number of repetitions (both RT groups performed three sets of 14 repetitions). With ageing, the loss of muscle mass is closely related to muscle denervation and a decrease in circulating anabolic hormones (e.g. growth hormone, insulin-like growth factors I and II), 1,9,10 which may be counteracted by the use of HL-RT, especially given its superiority over LL-RT in improvement of maximal muscle strength and activation. 3,6,7 Additionally, the recent studies and guidelines in chronic disease patients (such as cancer, 11,12 coronary artery disease, 13 chronic kidney disease, 14–16 chronic pulmonary disease 17) with higher risk of sarcopenia 2 have replaced LL-RT with progressive ML-to-HL-RT or solely HL-RT.
Purpose:
This study compared the effects of heavy resisted sprint training (RST) versus unresisted sprint training (UST) on sprint performance among adolescent soccer players.
Methods:
Twenty-four ...male soccer players (age: 15.7 0.5 y; body height: 175.7 9.4 cm; body mass: 62.5 9.2 kg) were randomly assigned to the RST group (n = 8), the UST group (n = 10), or the control group (n = 6). The UST group performed 8 × 20 m unresisted sprints twice weekly for 4 weeks, whereas the RST group performed 5 × 20-m heavy resisted sprints with a resistance set to maximize the horizontal power output. The control group performed only ordinary soccer training and match play. Magnitude-based decision and linear regression were used to analyze the data.
Results:
The RST group improved sprint performances with moderate to large effect sizes (0.76–1.41) across all distances, both within and between groups (>92% beneficial effect likelihood). Conversely, there were no clear improvements in the UST and control groups. The RST evoked the largest improvements over short distances (6%–8%) and was strongly associated with increased maximum horizontal force capacities (
r
= .9). Players with a preintervention deficit in force capacity appeared to benefit the most from RST.
Conclusions:
Four weeks of heavy RST led to superior improvements in short-sprint performance compared with UST among adolescent soccer players. Heavy RST, using a load individually selected to maximize horizontal power, is therefore highly recommended as a method to improve sprint acceleration in youth athletes.
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