completely occlude arterial blood flow (arterial occlusion pressure [AOP]). The most frequently applied method to determine blood flow and thus AOP is the Doppler ultrasound (DU) technique. However, despite its high accuracy, the practicability of this gold-standard method 16 , 17 is limited, mainly owing
Zhen Zeng, Christoph Centner, Albert Gollhofer and Daniel König
Scott Cocking, Mathew G. Wilson, David Nichols, N. Timothy Cable, Daniel J. Green, Dick H. J. Thijssen and Helen Jones
“traditional” IPC protocol consists of 3 × 5- or 4 × 5-minute bouts of occlusion. More recently, studies have separately employed alternative IPC protocols (altering the number of IPC cycles, tissue occlusion area, and cuff location) with the aim of observing greater performance and clinical outcomes. There
Sarah J. Willis, Grégoire P. Millet and Fabio Borrani
During conditions of systemic hypoxia and/or ischemia via vascular occlusion (blood flow restriction, BFR), there is reduced oxygen availability. The different intrinsic vascular mechanisms of hypoxia-induced compensatory vasodilation 1 or BFR-induced increased vascular resistance 2 may influence
Brian Killinger, Jakob D. Lauver, Luke Donovan and John Goetschius
exercises for both conditions, but not inflated for the control condition. During the BFR condition, the cuff was inflated to 80% 17 of the participant’s limb occlusion pressure. Participant’s limb occlusion pressure, the pressure necessary to achieve full blood flow occlusion, was determined prior to the
Mickaël Begon and Patrick Lacouture
A marker has to be seen by at least two cameras for its three-dimensional (3-D) reconstruction, and the accuracy can be improved with more cameras. However, a change in the set of cameras used in the reconstruction can alter the kinematics. The purpose of this study was to quantify the harmful effect of occlusions on two-dimensional (2-D) images and to make recommendations about the signal processing. A reference kinematics data set was collected for a three degree-of-freedom linkage with three cameras of a commercial motion analysis system without any occlusion on the 2-D images. In the 2-D images, some occlusions were artificially created based on trials of real cyclic motions. An interpolation of 2-D trajectories before the 3-D reconstruction and two filters (Savitsky–Golay and Butterworth filters) after reconstruction were successively applied to minimize the effect of the 2-D occlusions. The filter parameters were optimized by minimizing the root mean square error between the reference and the filtered data. The optimal parameters of the filters were marker dependent, whereas no filter was necessary after a 2-D interpolation. As the occlusions cause systematic error in the 3-D reconstruction, the interpolation of the 2-D trajectories is more appropriate than filtering the 3-D trajectories.
Sonia Julià-Sánchez, Jesús Álvarez-Herms, Hannes Gatterer, Martin Burtscher, Teresa Pagès and Ginés Viscor
Contradictory results are still reported on the influence of dental occlusion on the balance control. We attempted to determine whether there are differences in balance between opposed dental occlusion (Intercuspal position (ICP)/“Cotton rolls” mandibular position [CR]) for two extreme levels of stability (stable/unstable). Twenty-five subjects were monitored under both dental occlusion and level of stability conditions using an unstable platform Balance System SD. The resulting stability index suggests that body balance is significantly better when dental occlusion is set in CR (p < .001) in unstable but not in stable conditions. Occlusal traits significantly influencing postural control were Angle Class (p < .001), crowding (p = .006), midline deviation (p < .001), crossbite (p < .001), anterior open bite (p = .05), and overjet (p = .01). It could be concluded that the sensory information linked to the dental occlusion for the balance control comes strongly into effect in unstable conditions.
Eiji Yamada, Takashi Kusaka, Satoshi Tanaka, Satoshi Mori, Hiromichi Norimatsu and Susumu Itoh
To investigate changes in motor-unit activity and muscle oxygenation (MO) during isometric contraction with and without vascular occlusion using surface electromyography (EMG) and near-infrared spectroscopy.
Design and Setting:
MO and EMG of the right vastus medialis muscle were measured during isometric contraction at 30%, 50%, and 70% maximal voluntary contraction (MVC), with and without vascular occlusion.
6 healthy men.
Integrated EMG (IEMG) and mean power frequency were significantly higher with vascular occlusion at 30% and 50% MVC. MO reduction at each load was significantly lower with vascular occlusion. A significant positive correlation was found between IEMG and changes in MO level under both conditions.
These results suggest that oxygen supply to active muscles was impaired by occlusion and that type II fibers were then preferentially recruited, which suggests that hypertrophy occurs in low-intensity exercise in patients with limitations resulting from advanced age, pain, or postsurgery limitation.
Mathias T. Vangsoe, Jonas K. Nielsen and Carl D. Paton
design overview of 4 trials: IPC, PAP, CON, and SELF (N = 12). Gray boxes represent 5-minute occlusion at 200 mm Hg, followed by 5 minutes of reperfusion (white boxes). CON indicates control; IPC, ischemic preconditioning; PAP, postactivation potentiation; SELF, self-selected; TT, time trial. Performance
Christian J. Cook, Liam P. Kilduff and C. Martyn Beaven
To examine the effects of moderate-load exercise with and without blood-flow restriction (BFR) on strength, power, and repeated-sprint ability, along with acute and chronic salivary hormonal parameters.
Twenty male semiprofessional rugby union athletes were randomized to a lower-body BFR intervention (an occlusion cuff inflated to 180 mmHg worn intermittently on the proximal thighs) or a control intervention that trained without occlusion in a crossover design. Experimental sessions were performed 3 times a week for 3 wk with 5 sets of 5 repetitions of bench press, leg squat, and pull-ups performed at 70% of 1-repetition maximum.
Greater improvements were observed (occlusion training vs control) in bench press (5.4 ± 2.6 vs 3.3 ± 1.4 kg), squat (7.8 ± 2.1 vs 4.3 ± 1.4 kg), maximum sprint time (−0.03 ± 0.03 vs –0.01 ± 0.02 s), and leg power (168 ± 105 vs 68 ± 50 W). Greater exercise-induced salivary testosterone (ES 0.84–0.61) and cortisol responses (ES 0.65–0.20) were observed after the occlusion intervention sessions compared with the nonoccluded controls; however, the acute cortisol increases were attenuated across the training block.
Occlusion training can potentially improve the rate of strength-training gains and fatigue resistance in trained athletes, possibly allowing greater gains from lower loading that could be of benefit during high training loads, in competitive seasons, or in a rehabilitative setting. The clear improvement in bench-press strength resulting from lower-body occlusion suggests a systemic effect of BFR training.
Damian Farrow, Bruce Abernethy and Robin C. Jackson
Two experiments were conducted to examine whether the conclusions drawn regarding the timing of anticipatory information pick-up from temporal occlusion studies are influenced by whether (a) the viewing period is of variable or fixed duration and (b) the task is a laboratory-based one with simple responses or a natural one requiring a coupled, interceptive movement response. Skilled and novice tennis players either made pencil-and-paper predictions of service direction (Experiment 1) or attempted to hit return strokes (Experiment 2) to tennis serves while their vision was temporally occluded in either a traditional progressive mode (where more information was revealed in each subsequent occlusion condition) or a moving window mode (where the visual display was only available for a fixed duration with this window shifted to different phases of the service action). Conclusions regarding the timing of information pick-up were generally consistent across display mode and across task setting lending support to the veracity and generalisability of findings regarding perceptual expertise in existing laboratory-based progressive temporal occlusion studies.