Weightlifting

This chapter briefly outlines the biomechanical and physiological principles behind training for the sport of weightlifting

Training of a weightlifter: a scientific approach

This breakout presentation was delivered at the 2019 United Kingdom Strength and Conditioning Conference (UKSCA). It outlines the monitoring and training of a national weightlifter

P2X7 Receptor Modulation of Visual Responses in the Retina

Adenosine 5’ triphosphate (ATP)-gated P2X7 receptors (P2X7Rs) are known to act as conduits for photoreceptor and retinal ganglion cell (RGC) damage, consequences of various neurodegenerative conditions within the visual pathway. Growing evidence supports the notion that P2X7Rs and associated inflammatory mediators may coordinate microglia, the resident immune cells of the central nervous system (CNS), to play a genuine role in modulating neurotransmission. This study aimed to characterise the role of P2X7Rs in modulating outer and inner retinal function within the rod-mediated pathway, and in the putative microglial-mediated modulation of signal transmission in the retina. Excitatory components of outer and inner retinal function were assessed by recording light-evoked, extracellular transretinal electroretinogram (ERG), and ON and OFF retinal ganglion cell (RGC) field excitatory postsynaptic potential (fEPSP) responses from the acutely isolated, dark-adapted, mouse retina. Alterations to microglial morphology, under similar conditions, were also explored. Initial experiments confirmed the excitatory responses as predominantly mediated via the ‘classic’ rod photoreceptor – rod-ON bipolar cell – AII amacrine cell pathway. With the use of selective P2X7R antagonists, it was shown that P2X7R activation directly modulated photoreceptor, ON bipolar cell and ON RGC function, but not OFF RGC function, through partially independent mechanisms. A novel finding of this study demonstrated that acute application of the microglia-activating bacterial component, lipopolysaccharide (LPS) modulated inner retinal function, possibly through a P2X7R- and Pannexin-1-associated mechanism of microglial ATP release. These results were supported by observations of early morphometric changes to microglia caused by P2X7R activation and LPS, as revealed by immunofluorescence labelling and confocal laser scanning microscopy. Since changes in neurotransmission and microglial function are early indicators of neuropathology, these results contribute to the understanding of early neural-immune interactions in retinal disease, and in the central nervous system as a whole

Dark matter and stable bound states of primordial black holes

We present three reasons for the formation of gravitational bound states of primordial black holes,called holeums,in the early universe.Using Newtonian gravity and nonrelativistic quantum mechanics we find a purely quantum mechanical mass-dependant exclusion property for the nonoverlap of the constituent black holes in a holeum.This ensures that the holeum occupies space just like ordinary matter.A holeum emits only gravitational radiation whose spectrum is an exact analogue of that of a hydrogen atom. A part of this spectrum lies in the region accessible to the detectors being built.The holeums would form haloes around the galaxies and would be an important component of the dark matter in the universe today.They may also be the constituents of the invisible domain walls in the universe.Comment: 13 pages,2tables,for wider circulation,PD

Intra- and inter-day reliability of typical and alternative weightlifting variables during heavy cleans

The pull in weightlifting has previously been categorized into 3 phases: weighting 1 (W1), unweighting (UW), and weighting 2 (W2) (Enoka 1979). Research into the examination of weightlifting has typically utilized pulling derivatives initiated at or above the knee (Suchomel et al 2015; Haff et al 2012), which excludes a detailed examination of W1 and UW phases. Weightlifting is a sport initiated from floor level, which would imply that performance of W1 and UW may impact overall performance outcomes and therefore this study aimed to examine which variables can be collected throughout the entire duration of the pull, which of those are reliable within and between days, and which can be monitored for performance

Exercise technique: the push press

The push press exercise has been used for years by coaches as one of many tools to enhance an athletes’ physical development. Recent research has further validated this exercise to augment power development. Thus, the aim of this paper is to outline the benefits this exercise has for strength and conditioning coaches

Retroperitoneal fibrolipoma: A tumor bigger than its bite

Only five cases have been reported in literature We present a rare case of retroperitoneal fibrolipoma that presented as a large intraabdominal mass, review essential investigations and treatment given

The acute effects of heavy sled towing on subsequent sprint acceleration performance

Objectives: The purpose of this study was to assess the practical use of heavy sled towing and its acute implications on subsequent sprint acceleration performance. Design and Methods: Eight healthy male varsity team sport athletes (age: 21.8±1.8years, height: 185.5±5.0cm, weight: 88.8±15.7kg, 15m sprint time: 2.66±0.13s) performed sprints under three separate weighted sled towing conditions in a randomized order. Each condition consisted of one baseline unweighted sprint (4-min pre), the sled towing sprint protocol: (1) 1x50% body mass, (2) 2x50% body mass, (3) 3x50% body mass (multiple sprints interspersed with 90s recovery), and 3 post-testing unweighted sprints thereafter (4, 8, 12-min post). All sprints were conducted over a 15m distance. Results: Significantly faster sprint times for the 3x sled towing protocol were identified following 8-min of rest (p=0.025, d=0.46, 2.64±0.15s to 2.57±0.17s). When individual best sprint times were analyzed against baseline data, significantly faster sprint times were identified following both 1x (p=0.007, d=0.69, 2.69±0.07s to 2.64±0.07s) and 3x (p=0.001, d=0.62, 2.64±0.15s to 2.55±0.14s) sled towing protocols. Within the 3x condition, all athletes achieved fastest sprint times following 8–12 min of rest. Conclusions: The findings from the present study indicate that a repeated bout of sled towing (3x50% body mass) leads to the enhancement in subsequent sprint acceleration performance, following adequate, and individualized recovery periods

P2X7R modulation of visually evoked synaptic responses in the retina.

P2X7Rs are distributed throughout all layers of the retina, and thus, their localisation on various cell types puts into question their specific site(s) of action. Using a dark-adapted, ex vivo mouse retinal whole mount preparation, the present study aimed to characterise the effect of P2X7R activation on light-evoked, excitatory RGC ON-field excitatory post-synaptic potentials (fEPSPs) and on outer retinal electroretinogram (ERG) responses under comparable conditions. The pharmacologically isolated NMDA receptor-mediated RGC ON-fEPSP was reduced in the presence of BzATP, an effect which was significantly attenuated by A438079 and other selective P2X7R antagonists A804598 or AF27139. In physiological Krebs medium, BzATP induced a significant potentiation of the ERG a-wave, with a concomitant reduction in the b-wave and the power of the oscillatory potentials. Conversely, in the pharmacologically modified Mg(2+)-free perfusate, BzATP reduced both the a-wave and b-wave. The effects of BzATP on the ERG components were suppressed by A438079. A role for P2X7R function in visual processing in both the inner and outer retina under physiological conditions remains controversial. The ON-fEPSP was significantly reduced in the presence of A804598 but not by A438079 or AF27139. Furthermore, A438079 did not have any effect on the ERG components in physiological Krebs but potentiated and reduced the a-wave and b-wave, respectively, when applied to the pharmacologically modified medium. Therefore, activation of P2X7Rs affects the function in the retinal ON pathway. The presence of a high concentration of extracellular ATP would most likely contribute to the modulation of visual transmission in the retina in the pathophysiological microenvironment

Effects of concurrent activation potentiation on countermovement jump performance

The purpose of this study was to assess the effects of concurrent activation potentiation (CAP) on countermovement jump (CMJ) performance. Twenty-four resistance trained males (mean ± SD, age 25 ± 4 years; body mass: 78.7 ± 10.3 kg) performed a CMJ on a force plate under four different conditions: a) a control condition where the CMJ was performed with hands on hips and lips pursed, thus preventing jaw or fist contraction from occurring, b) a jaw condition where the CMJ was performed with maximal contraction of the jaw, c) a fist condition where the CMJ was performed with maximal contraction of the fists, and d) a combined condition where the CMJ was performed with maximal contraction of both jaw and fists. Jump height (JH), peak force (PF), rate of force development (RFD) and time to peak force (TTPF) were calculated from the vertical force trace. There was no significant difference in PF (P = 0.88), TTPF (P = 0.96), JH (P = 0.45), or RFD (P = 0.06) between the four conditions. Effect size (ES) comparisons suggests a potential for the BOTH condition to augment both PF (2.4%; ES: 0.62) and RFD (9.9%; ES: 0.94) over NORM. It is concluded that CAP via singular and combined contractions has no significant impact on CMJ performance, however, substantial inter-individual variation in the response to CAP was observed and such techniques may therefore warrant consideration on an individual basis