Influence of Air Resistance on Ground Reaction Forces During Treadmill Running

INTRODUCTION: Running is fundamentally driven by forces applied to the ground, eliciting ground reaction forces (GRFs) which accelerate the runner. These GRFs are divided into vertical, anteroposterior, and mediolateral components. As running speed alters, so do the patterns of these forces. By juxtaposing these GRF patterns with metabolic data, we can discern how movement patterns adapt across different running conditions. One of the key distinctions between treadmill and overground running is the influence of air resistance. METHODS: The study involved twenty-four active male runners experienced in achieving a sub-17-minute-5km or equivalent performance. The main objective was to examine the influence of air resistance on running biomechanics. Participants underwent two data collection sessions. During the sessions, various parameters such as height, weight were recorded, and the influence of different air resistance conditions on their running mechanics was studied. RESULTS: Braking Impulse, Propulsive Impulse, Horizontal Impulse, and Mean Force all demonstrated significant effects with respect to the wind conditions. Specifically, the effect of condition was significant for propulsive impulse and braking impulse, horizontal impulse, and mean force. These variables showed differences across the various wind conditions tested. CONCLUSION: We investigated the biomechanical effects of horizontal impeding forces on runners. Our results highlight how these forces alter running mechanics. With increased resistance, runners showed marked changes in propulsive and braking impulses, indicating adjustments in their gait. Aspects like ground time and stride length remained consistent, while horizontal forces primarily affected anterior-posterior running mechanics

Mechanisms of mechanosensation in Drosophila melanogaster proprioceptors

Proprioception is the ability to detect position in space. It is necessary for normal motor control and could share molecular mechanisms with other senses, such as hearing. These mechanisms are poorly understood and clarifying them may reveal novel targets for treatment of muscle spasticity, seizure and hardness of hearing. This research uses Drosophila models to clarify the behavioural role and molecular properties of proprioceptors; the dbd neuron and the chordotonal neurons. I hypothesise that the dbd neuron is both a pain and stretch receptor that requires DmPiezo to respond to both physiological and nociceptive stimuli. In contrast, evidence suggests that chordotonal neurons sense could sound and stretch stimuli through different mechanisms, which depend on nan/ iav/ NompC and DmPiezo respectively. We employed optogenetics, crawling, nociceptive reflex (‘pinch’ response), GCaMP imaging and whole-cell patch-clamp electrophysiology to investigate the role and mechanisms of mechanosensation in the dbd neuron. Similarly, I used crawling, hearing and GCaMP experiments to assess the role and mechanisms of mechanosensation in the chordotonal neurons. I found the dbd neuron difficult to investigate; a ‘nociceptive’ phenotype originally attributed to dbd neuron stimulation disappeared when the related driver, Bd-Gal4, was expressed in the background of a mutant (amos1) that lacks the dbd neuron. Moreover, while electrophysiology gave results like those published previously, my data were limited by issues including low seal values (~40MΩ, significantly lower than the desired 1GΩ) that were exacerbated by stretch. Chordotonal (ch) neurons were easier to study. GCaMP imaging of the larval ventral nerve cord showed that ch neurons respond to both tonal (1024Hz) and muscle contraction stimulation (mean ΔF/ F0 (%) 11.47 ± 2.93 and 7.56 ± 4.38, respectively). I imaged the ch neurons (lch1-5, vch1 and vchAB) directly, and doing so revealed some interesting spatial and temporal differences in response to sound, which implies specific tuning of neurons within the chordotonal neuron population(s)(s). GCaMP imaging also showed that CG17669, a gene with a human orthologue (DNAAF3) associated with primary ciliary dyskinesia, is necessary for ch neuron response to 1024Hz and muscle contraction. In conclusion, the behavioural role and mechanisms of the dbd neuron remain unclear and require further investigation. However, it appears that while the ch neurons can detect stretch (and so act as proprioceptors), this function is not required for normal movement in larvae. The ch neurons appear to be a sense organ with a single mechanism of mechanosensation, that is optimised for detection of tonal stimuli in the hearing range. Finally, this research is the first to: (1) image the response of vch1 and vchAB ch neurons response to sound; (2) provide evidence that subsets of Drosophila ch neurons may be tuned to respond to specific amplitudes and/ or frequencies; (3) use real-time calcium imaging to demonstrate the effect of CG17669 mutation on the function of ch neurons

TECHNIQUE COMPARISON OF MALE AND FEMALE HAMMER THROWERS

Distinct anthropometric differences occur between the sexes throwing the hammer that affect technique. No literature statistically compares the differences between male and female hammer throwers. The aim of this study was to determine the hammer throwing technique differences occurring between genders. The performances of 16 male and female throwers at the 2003 World Athletic Final and 13 male and female throwers from the 2003 USA Track and Field Nationals were examined. The best throw of each athlete was digitized and analyzed using the Peak Motus 8.2 motion analysis system. Results revealed that athlete mass, athlete height, velocity at release, timing components, and centripetal force were different between sexes

An Sp1 Modulated Regulatory Region Unique to Higher Primates Regulates Human Androgen Receptor Promoter Activity in Prostate Cancer Cells

Funding: This work was supported by the Chief Scientist’s Office (CSO) of the Scottish Government (http://www.cso.scot.nhs.uk/): CWH (CZB-4-477) and IH (ETM/382).Peer reviewedPublisher PD

The effect of a near-maximal effort one-hour run on preferred and optimal stride rate and vertical stiffness

Experienced runners naturally optimize stride rate in a manner that minimizes oxygen uptake at given running speeds. However, as runners become fatigued, preferred stride rate often decreases. Whether such changes with fatigue occur in parallel with changes in optimal stride rate is unknown. This study's focus was on determining whether experienced runners self-optimize stride rate throughout a near-maximal one-hour run. A secondary focus was to determine if vertical stiffness is associated with decreases in stride rate. Seventeen subjects completed a one-hour near-maximal effort run on a treadmill. After the first five minutes, preferred and optimal stride rates were measured. Ground reaction force data were used to determine preferred stride rate averaged over ten strides. Runners completed five two-minute segments of running at preferred stride rate, 4% and 8% above and below their preferred rate. Oxygen uptake was measured during the second minute of each two-minute segment. Fitting a second-degree polynomial through oxygen uptake versus stride rate data provided a minimum value for oxygen uptake from which optimal stride rate was determined. Fifty minutes into the run, optimal stride rate was measured again. Repeated measures ANOVA showed no difference between preferred and optimal stride rates at the beginning or at the end of the run, but a decrease in optimal stride rate was observed from beginning to end. About half of the subjects decreased preferred and optimal stride rate over the course of the hour run while the other half showed little or no change. Vertical stiffness was measured based upon center of mass vertical displacement and active peak force. Decreases in preferred stride rate over the course of the hour run were expected to be associated with decreases of vertical stiffness. However, the changes in stride rate and vertical stiffness were small; no strong relationship was observed (R²=0.12). Experienced runners have demonstrated the capability to self-optimize stride rate at the beginning and near the end of a one hour run. This ability was observed for runners with substantial shifts of stride rate with fatigue as well as for runners with no change of stride rate with fatigue

Biomechanical Indicators of Steeplechase Hurdle Success

The steeplechase is a long-distance running event that requires competitors to jump over 28 hurdles and 7 water jumps over the course of the race. This frequent jumping means that hurdling technique is important and the ability to maintain speed over the barriers can help a runner succeed. PURPOSE: To determine which variables predict maintenance of speed while hurdling in the steeplechase. METHODS: Data were collected at the USATF outdoor championships and Olympic Trials from 2011 to 2023 for both men and women. A Sony video camera running at 120 Hz was used to evaluate several aspects of the runner’s mechanics as well as their horizontal velocity before jumping and after landing. The ratio of exit to approach velocity was taken and used as our measure of how successful the jump was, a ratio closer to one means they lost less velocity when jumping over the hurdle. A stepwise linear regression was done for both men and women and was used to determine which variables best predicted hurdle success. RESULTS: Men and women had slightly different variables that predicted successful hurdling. The model for women had an R2 of 0.179 (p \u3c 0.001). For men the R2 was 0.060 (p\u3c0.001). Both models included increased takeoff distance and greater knee flexion angle at takeoff as beneficial. Both models also included the lead knee extension when going over the hurdle, but it was a negative relationship in women and a positive relationship in men. The model for the men also included a less extended hip at takeoff. The model for the women added the clearance of the hip over the hurdle. CONCLUSION: Coaches should focus on having athletes take off a little farther from the barrier and working to have a more flexed knee at takeoff. Men and women have differing hurdling techniques in the steeplechase. While some of the same variables are important, there are also distinct differences. When coaching athletes these differences in technique should be accounted for

Biomechanical Indicators of Water Jump Performance

During the course of the steeplechase track event athletes pass through one water jump obstacle per each of seven laps. There are many different elements of technique that can be used to improve maintenance of horizontal velocity through each obstacle. PURPOSE: This study investigated which biomechanical factors were correlated with higher ratios of exit velocity to approach velocity while negotiating the water jump obstacle. METHODS: Biomechanical data were gathered from the steeplechase event for both men and women at the USATF Outdoor Championships and Olympic Trials. Data were included from 2011 through 2023. Biomechanical data were measured from recorded video using Dartfish video analysis software. Knee and hip angles, time of stepping on the barrier, and take off and landing distances were measured at key points of the movement along with approach and exit velocities. These velocities were measured through 2m sections prior to the barrier and after leaving the water pit. A stepwise linear regression tested for correlations between the exit to approach velocities to a variety of biomechanical measurements. RESULTS: The predictor variables for both men and women were the same, including: landing distance, pushoff angle, and barrier time normalized to average velocity (Women R2=0.290, p2=0.236, pCONCLUSION: According to our data, steeplechase athletes can improve horizontal velocity maintenance through the water jump obstacle by landing further from the barrier into the water, extending more at the knee while pushing off the barrier, and spending less time on the barrier. While previous research showed women lose more velocity during the water jump, the correlated factors were the same and were even entered into the model in the same order showing coaches and athletes the importance of where to focus their technique improvements

Active transport and energy conservation in Escherichia coli

1. The main aim of this work was to compare the efficiencies of growth of various phenotypes of Escherichia coli. Several strains were grown in arithmetic (Wallace, 1975), chemostat and batch cultures. Values for maintenance energies were derived in order to calculate maximum growth yields in terms of carbon and oxygen. Efficiencies of ATP synthesis (expressed as P/O ratios) were calculated from yields using the assumption that the energy required for cellular biosynthesis under anaerobic conditions applied to the aerobic cultures. P/O ratios were then compared with H+/O ratios of the harvested bacteria, 2. The maintenance requirement was lower for arithmetic cultures than for chemostat cultures, suggesting that dropwise addition of nutrient in chemostat culture might uncouple cellular growth from energy supply. 3. E.coli ML30 (which is lac-inducible) had the same maintenance requirement as its lac-constitutive derivative, ML3O8, . when it was grown on a non-inducing carbon source. The gratuitous synthesis and turnover of the lac enzymes therefore make negligible contributions to maintenance. 4. There were at least two classes of reaction responsible for maintenance one of which was independent of temperature while the other was strongly temperature-dependent. The latter had an activation energy similar to that of protein denaturation, suggesting that part of the maintenance requirement may be for macromolecular organisation. 5. Bacteria grown on glucose, glycerol, maltose, galactose or mannitol had P/O ratios of 2, while those grown on lactose, gluconate or glucose 6-phosphate had P/O ratios of 3. The phenotypes with the higher efficiency of energy conservation all transported their carbon sources- by a proton-symport mechanism. 6. In pulse-oxidant determinations of H+/O ratios, cells with a P/O ratio of 3 extruded more protons than those with P/O ratio of 2, This is an independent confirmation of the conclusion derived from growth yields. 7. Growth on lactose in batch culture or in the chemostat also gave a P/O ratio of 3. High P/O ratios are therefore not peculiar to arithmetic culture. 8. Bacteria which had high P/O ratios had high maintenance coefficients. It is speculated that the additional maintenance requirement may be spent for organisation of a more efficient electron transport chain. 9. A period of logarithmic growth on the proton-symported substrate was required for the extra coupling site to be expressed, since cells which had previously been grown on glycerol with P/O ratio of 2, grew on lactose with a P/O ratio of 2 under carbon limitation in arithmetic culture. 10. E.coli ML30 grew on gluconate with a P/O ratio of 3. Therefore, the lac enzymes themselves were not required for the higher growth efficiency. 11. When bacteria which had been grown on lactose were starved for 2 h, they lost the additional energy-coupling site as judged by H+/O ratios. The lac permease also decayed, indicating a possible relationship between the two processes. 12. Cultures of E.coli ML3O8 grown on either lactose or glycerol had active lac permease, but only the lactose phenotype had its H+/O ratio enhanced by adding non-metabolisable galactosides. Transport in cells growing on lactose can therefore affect energy conservation. 13. Addition of salt (NaCl, Na2SO4) to growth media reduced the P/O ratios of cultures but did not significantly change their H+/O ratios. Salt must therefore either decrease the efficiency of the ATPase machinery or have an un-coupling effect on the membrane. 14. Cultures grew on lactose/glucose mixtures with a P/O ratio of 3. Therefore when the additional coupling site was present, all carbon sources were metabolised through the same system with high efficiency. 15. The additional coupling site found in lactose/grown bacteria was not due to energy-conserving transhydrogenase activity nor to an alternative energy-conserving terminal oxidase. In the absence of other experimental data on the composition of the electron transport chain of this phenotype, models are presented to explain the results in terms of novel electron carriers or rearrangement within the membrane of preexisting electron carriers. 16. It is concluded that an additional site of energy conservation is synthesised by E.coli in response to transport of carbon sources which enter the cell via proton symport, This conclusion implies a relationship between active transport and electron transport which have hitherto been assumed to work independently of each other

Sovereignty and contemporary Scottish constitutional debate

This thesis critically analyses the juristic concept of sovereignty in contemporary Scottish constitutional debate. ‘Parliamentary Sovereignty’ – the shibboleth of the British public lawyer – has by now weathered many attacks but remains stubbornly in place as the foundation of the United Kingdom’s constitution. The problems this has thrown up for the accommodation of Scotland in the famously vague yet remarkably resilient structures of the British constitution are well-documented, and they have provided useful ammunition for a resurgent political nationalism. A Scottish tradition of popular sovereignty has increasingly been invoked in recent decades as a counter to the dominance of Westminster’s absolute legislative authority. This ostensibly one-sided fight takes place in a field of inquiry most often avoided by British public lawyers: the interface between law and politics. The distinction between legal and political sovereignty is observed dogmatically in orthodox jurisprudence, and it has even coloured more radical attempts to re-imagine what sovereignty might mean in an era when many contend that sub-state and supra-state influences are reshaping the modern polity. It will be argued that a failure to properly theorise the juncture of law and politics in traditional Anglocentric scholarship has led to a situation in which the concept of sovereignty has become so misunderstood that its significance is routinely overlooked. Both extant pluralist treatments of sovereignty specifically addressed to the Scottish context and its recent invocations in contemporary constitutional debate have depended on erroneous or impoverished constructions of its meaning and function. It is submitted that the model of sovereignty developed by Martin Loughlin provides a superior analytical framework for investigations into the current constitutional position of Scotland, and offers a more illuminating account of the forces which are at work in a nascent Scottish public sphere

Self-optimization of Stride Length Among Experienced and Inexperienced Runners

International Journal of Exercise Science 10(3): 446-453, 2017. Experienced runners appear to naturally select a stride length which is optimal for minimizing oxygen uptake. However, whether this ability is naturally built into the human body or whether it is learned through experience has not been previously tested. This study investigated whether inexperienced runners are as capable as experienced runners of self-optimizing stride length to minimize oxygen uptake. Thirty-three subjects (nineteen experienced and fourteen inexperienced) ran for twenty-minutes while preferred and economical stride lengths were measured. A t-test checked for differences between the experienced and inexperienced groups in the percent increase of oxygen uptake due to not running at the most economical stride length. No difference was found between groups with the increase in oxygen uptake due to not being optimized (p=0.47). The average percent increase in oxygen uptake above the most economical for inexperienced and experienced runners was 1.8% and 1.2% respectively. We concluded that inexperienced and experienced runners are equally capable of matching preferred stride length to economical stride length, thus athletes and coaches do not need to alter runner’s stride length when economy is the main concern