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1.
Short-Term Creatine Loading Improves Total Work and Repetitions to Failure but Not Load-Velocity Characteristics in Strength-Trained Men.
Feuerbacher, JF, von Schöning, V, Melcher, J, Notbohm, HL, Freitag, N, Schumann, M
Nutrients. 2021;(3)
Abstract
This study assessed the effects of a 7-day creatine (CRE) supplementation on the load-velocity profile and repeated sub-maximal bouts in the deep squat using mean propulsive velocity (MPV) and mean propulsive power (MPP). Eleven strength-trained men (31.4 ± 5.4 years) supplemented 0.3 g·kg-1·d-1 CRE or a placebo (PLA, maltodextrin) for seven days in a randomized order, separated by a 30-day washout period. Prior to and after the supplementation, the subjects performed an incremental maximal strength (1RM) test, as well as 3 × 10 repetitions and a repetitions-to-failure test (RFT), all at 70% 1RM. Maximal strength remained statistically unaltered in CRE (p = 0.107) and PLA (p = 0.568). No statistical main effect for time (p = 0.780) or interaction (p = 0.737) was observed for the load-velocity profile. The number of repetitions during RFT remained statistically unaltered in both conditions (CRE: +16.8 ± 32.8%, p = 0.112; PLA: +8.2 ± 47.2%, p = 0.370), but the effect size was larger in creatine compared to placebo (g = 0.51 vs. g = 0.01). The total work during RFT increased following creatine supplementation (+23.1 ± 35.9%, p = 0.043, g = 0.70) but remained statistically unaltered in the placebo condition (+15.0 ± 60.8%, p = 0.801, g = 0.08; between conditions: p = 0.410, g = 0.25). We showed that CRE loading over seven days did not affect load-velocity characteristics but may have increased total work and power output during submaximal deep squat protocols, as was indicated by moderate effect sizes.
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Load characteristics following transfemoral amputation in individuals fitted with bone-anchored prostheses: a scoping review protocol.
Pather, S, Vertriest, S, Sondergeld, P, Ramis, MA, Frossard, L
JBI database of systematic reviews and implementation reports. 2018;(6):1286-1310
Abstract
The main purpose of this scoping review is to characterize loading information applied on the residuum of individuals with transfemoral amputation fitted with an osseointegrated fixation for bone-anchored prostheses.The objectives of this scoping review are: i) to map the scope of loading variables, and ii) to report the range of magnitude of loads that has been directly measured using a portable kinetic recording apparatus fitted at the distal end of the residuum during rehabilitation exercises, standardized and unscripted activities of daily living, and adverse events.The specific review questions are.
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Subjects with medial and lateral tibiofemoral articular cartilage defects do not alter compartmental loading during walking.
Van Rossom, S, Khatib, N, Holt, C, Van Assche, D, Jonkers, I
Clinical biomechanics (Bristol, Avon). 2018;:149-156
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Abstract
BACKGROUND Healthy cartilage is essential for optimal joint function. Although, articular cartilage defects are highly prevalent in the active population and hamper joint function, the effect of articular cartilage defects on knee loading is not yet documented. Therefore, the present study compared knee contact forces and pressures between patients with tibiofemoral cartilage defects and healthy controls. Potentially this provides additional insights in movement adaptations and the role of altered loading in the progression from defect towards OA. METHODS Experimental gait data collected in 15 patients with isolated cartilage defects (8 medial involvement, 7 lateral-involvement) and 19 healthy asymptomatic controls was processed using a musculoskeletal model to calculate contact forces and pressures. Differences between two patient groups and controls were evaluated using Kruskal-Wallis tests and individually compared using Mann-Whitney-U tests (alpha <0.05). FINDINGS The patients with lateral involvement walked significantly slower compared to the healthy controls. No movement adaptations to decrease the loading on the injured condyle were observed. Additionally, the location of loading was not significantly affected. INTERPRETATION The current results suggest that isolated cartilage defects do not induce significant changes in the knee joint loading distribution. Consequently, the involved condyle will capture a physiological loading magnitude that should however be distributed over the cartilage surrounding the defect. This may cause local degenerative changes in the cartilage and in combination with inflammatory responses, might play a key role in the progression from articular cartilage defect to a more severe OA phenotype.
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The Effect of Exercise-Induced Muscle Damage After a Bout of Accentuated Eccentric Load Drop Jumps and the Repeated Bout Effect.
Bridgeman, LA, Gill, ND, Dulson, DK, McGuigan, MR
Journal of strength and conditioning research. 2017;(2):386-394
Abstract
Bridgeman, LA, Gill, ND, Dulson, DK, and McGuigan, MR. The effect of exercise induced muscle damage after a bout of accentuated eccentric load drop jumps and the repeated bout effect. J Strength Cond Res 31(2): 386-394, 2017-Although previous studies have investigated exercise-induced muscle damage (EIMD) after a bout of unloaded drop jumps (DJs), none have investigated the effects of accentuated eccentric load (AEL) DJs on EIMD. The purpose of this study was to investigate the effects of 30 and 50 AEL DJs on strength, jump performance, muscle soreness, and blood markers. Eight resistance trained athletes participated in this study. In week 1, baseline countermovement jump (CMJ), squat jump (SJ), concentric and eccentric peak force (PF), creatine kinase, and muscle soreness were assessed. Subjects then completed 30 AEL DJs and baseline measures were retested immediately postintervention, 1, 24, and 48 hours later. Two weeks later, the subjects completed the same protocol with an increase in AEL DJ volume (50). Subjects' SJ height was reduced in week 1 compared with week 3, postintervention, 1, 24, and 48 hours later (ES = -0.34, -0.44, -0.38, and -0.40). Subjects' CMJ height was reduced in week 1 compared with week 3, postintervention, 1, and 24 hours later (ES = -0.37, -0.29, and -0.39). Concentric PF was reduced in week 1 compared with week 3, postintervention and 24 and 48 hours later (ES = -0.02, -0.23, and -0.32). Eccentric PF was reduced in week 1 compared with week 3, postintervention, 24, and 48 hours later (ES = -0.24, -0.16, and -0.50). In this sample, 30 AEL DJs attenuated the effects of EIMD following which 50 AEL DJs completed 2 weeks later.
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Osteocyte Mechanobiology.
Uda, Y, Azab, E, Sun, N, Shi, C, Pajevic, PD
Current osteoporosis reports. 2017;(4):318-325
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Abstract
PURPOSE OF REVIEW Over the past decades, osteocytes have emerged as mechano-sensors of bone and master regulators of bone homeostasis. This article summarizes latest research and progress made in understanding osteocyte mechanobiology and critically reviews tools currently available to study these cells. RECENT FINDINGS Whereas increased mechanical forces promote bone formation, decrease loading is always associated with bone loss and skeletal fragility. Recent studies identified cilia, integrins, calcium channels, and G-protein coupled receptors as important sensors of mechanical forces and Ca2+ and cAMP signaling as key effectors. Among transcripts regulated by mechanical forces, sclerostin and RANKL have emerged as potential therapeutic targets for disuse-induced bone loss. In this paper, we review the mechanisms by which osteocytes perceive and transduce mechanical cues and the models available to study mechano-transduction. Future directions of the field are also discussed.
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MR-based in vivo follow-up study of Achilles tendon volume and hydration state after ankle-loading activity.
Grosse, U, Syha, R, Gatidis, S, Grözinger, G, Martirosian, P, Partovi, S, Nikolaou, K, Robbin, MR, Schick, F, Springer, F
Scandinavian journal of medicine & science in sports. 2016;(10):1200-8
Abstract
The purpose of this study was to evaluate temporal alterations of the Achilles tendon volume and hydration state after cross-country-running. Achilles tendons of six untrained participants were examined on a 3T MR-scanner before running, immediately afterwards, and in the following 24, 48, and 72 h. Using a 3D-UTE sequence, caudal (CA) and cranial (CR) mid-portion tendon areas were examined with off-resonance saturation ratios (OSR) and T2* relaxation times. Tendon volume was measured with a self-written Matlab-based automated contour detection algorithm (AVAT) in submillimeter T2-weighted MR images. A significant influence of running in caudal (P = 0.017) and cranial OSR values (P = 0.001), tendon volume (P = 0.024), and cranial T2* measurements (P = 0.046), but not in caudal T2* values (P = 0.298) were found. In detail, mean individual OSR and tendon volume measurements demonstrated a similar but inverted course in their values after exercise: initially, OSR values increased after running (and tendon volume decreased), while subsequently a decrease of OSR values (with an increase of tendon volume) could be observed. OSR and tendon volume measurements are able to detect a physiological response of tendons to a mechanical stimulus. After a transient decrease of free water in the Achilles tendon, an increase with a maximum free water content 48 h after ankle loading and a tendency toward normalization after 72 h was found.
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Bone Response of Loaded Periodontal Ligament.
Dutra, EH, Nanda, R, Yadav, S
Current osteoporosis reports. 2016;(6):280-283
Abstract
The tooth-periodontal ligament-alveolar bone complex acts symbiotically to dissipate the mechanical loads incurred during mastication and/or orthodontic tooth movement. The periodontal ligament functions both in the tension and compression. At the molecular and celleular levels, the loads in the periodontal ligament trigger mechanobiological events in the alveolar bone, which leads to bone modeling and remodeling. The current review focuses on the bone response to mechanical loading of the periodontal ligament on the tension and pressure sides. Understanding the bone response has major implications for dentistry, including a better understanding of the different types of orthodontic tooth movement.
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Hormonal Responses to Active and Passive Recovery After Load Carriage.
Taipale, RS, Heinaru, S, Nindl, BC, Vaara, JP, Santtila, M, Häkkinen, K, Kyröläinen, H
Journal of strength and conditioning research. 2015;:S149-53
Abstract
Military operations often induce fatigue resulting from load carriage. Recovery promotes military readiness. This study investigated the acute effects of AR vs. PR after load carriage on maximal isometric leg extension force (MVC) and serum hormonal concentrations. Male reservists (27 ± 3 years, 180 ± 7 cm, 74 ± 11 kg, V[Combining Dot Above]O2max 64 ± 9 ml·kg⁻¹·min⁻¹) completed PR (n = 8) or AR (n = 8) after 50 minutes of loaded (16 kg) uphill (gradient 4.0%) treadmill marching at individual anaerobic threshold. No differences were observed between groups in relative changes in MVC during the marching loading, after AR or PR or the next morning. Significant differences in relative responses to AR and PR postmarching loading were observed in serum testosterone (T), cortisol, and sex-hormone binding globulin immediately post AR and PR; however the next morning, all serum hormone concentrations had returned to normal. This study did not reveal any significant differences between the effects of AR and PR after an hour-long marching protocol at approximately anaerobic threshold on MVC or serum hormones the morning after the experimental marching protocol. Thus, based on the variable measured in this study, marching performed by physically fit army reservists at an intensity at or below anaerobic threshold may not necessitate specialized recovery protocols.
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Weight-Bearing in the Nonoperative Treatment of Acute Achilles Tendon Ruptures: A Randomized Controlled Trial.
Young, SW, Patel, A, Zhu, M, van Dijck, S, McNair, P, Bevan, WP, Tomlinson, M
The Journal of bone and joint surgery. American volume. 2014;(13):1073-1079
Abstract
BACKGROUND The rate of Achilles tendon ruptures is increasing, but there is a lack of consensus on treatment of acute injuries. The purpose of this trial was to compare outcomes of weight-bearing casts with those of traditional casts in the treatment of acute Achilles tendon ruptures. METHODS Eighty-four patients with an acute Achilles tendon rupture were recruited over a two-year period. Patients were randomized to be treated with either a weight-bearing cast with a Böhler iron or a non-weight-bearing cast for eight weeks. Patients underwent muscle dynamometry testing at six months, with additional follow-up at one and two years. The primary outcomes that were assessed were the rerupture rate and the time taken to return to work. Secondary outcomes included return to sports, ankle pain and stiffness, footwear restrictions, and patient satisfaction. RESULTS There were no significant differences between groups with regard to patient demographics or activity levels prior to treatment. At the time of follow-up at two years, one (3%) of the thirty-seven patients in the weight-bearing group and two (5%) of the thirty-seven in the non-weight-bearing group had sustained a rerupture (p = 0.62). The patients in the weight-bearing group experienced less subjective stiffness at one year. There were no significant differences in time taken to return to work, Leppilahti scores, patient satisfaction, pain, or return to sports between the groups. CONCLUSIONS Use of weight-bearing casts for the nonoperative treatment of Achilles tendon ruptures appears to offer outcomes that are at least equivalent to those of non-weight-bearing casts. The overall rerupture rate in this study was low, supporting the continued use of initial nonoperative management for the treatment of acute Achilles tendon ruptures. LEVELS OF EVIDENCE Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
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Grip force and heart rate responses to manual carrying tasks: effects of material, weight, and base area of the container.
Lee, TH, Tseng, CY
International journal of occupational safety and ergonomics : JOSE. 2014;(3):377-83
Abstract
This study recruited 16 industrial workers to examine the effects of material, weight, and base area of container on reduction of grip force (ΔGF) and heart rate for a 100-m manual carrying task. This study examined 2 carrying materials (iron and water), 4 carrying weights (4.4, 8.9, 13.3, 17.8 kg), and 2 base areas of container (24 × 24 cm, 35 × 24 cm). This study showed that carrying water significantly increased ΔGF and heart rate as compared with carrying iron. Also, ΔGF and heart rate significantly increased with carrying weight and base area of container. The effects of base area of container on ΔGF and heart rate were greater in carrying water condition than in carrying iron condition. The maximum dynamic effect of water on ΔGF and heart rate occurred when water occupied ~60%-80% of full volume of the container.