10-m Time Research Articles

WITHDRAWN: The decrement in swimming performance following an increase in training volume is associated with muscle fibre typology

<h2>Abstract</h2><h3>Objectives</h3> We examined if muscle fibre typology (MFT) was associated with the magnitude of change in performance following alterations in swimming training volume in highly-trained swimmers. <h3>Design</h3> Single group intervention. <h3>Methods</h3> Ten swimmers (<i>n</i> = 2 female) completed four consecutive training phases: i) 2-wk normal training (NT); ii) 1-wk decrease (DEC1; 30 % decrease in volume) iii) 3-wk higher-volume training (HVT; i.e., 25 % increase from NT), and iv) 1-wk decrease (DEC2; 30 % decrease in volume). Swimmers performed a 200-m freestyle time trial (200-m TT), assessments of lower and upper-body power and a 10- and 30-s maximal tethered swimming test in the 2 days directly following each training phase. MFT of the gastrocnemius and soleus was estimated by quantification of muscle carnosine concentration using proton magnetic resonance spectroscopy in the week post-DEC2 and expressed as a carnosine aggregated z-score (CAZ-score). <h3>Results</h3> Some, but not all, performance-related and physical tests were affected by alterations to training volume. The relative increase in the 200-m TT time (i.e., slower time) from DEC1 (2:13.3 ± 00:07.3 m:ss.0) to HVT (2:16.0 ± 00:08.4) was associated with CAZ-score (<i>r</i> = 0.697, <i>p</i> = 0.025). 200-m TT performance was restored following DEC2 but there was no performance supercompensation. <h3>Conclusion</h3> The results of this study suggest that swimmers with a greater estimated proportion of type I fibres were better able to tolerate a short-term period of increased training volume. Nonetheless, a progressive decrease in training volume over 7 d was not sufficient to promote performance supercompensation in highly-trained swimmers.

Inter-stroke steadiness: a new kinematic variable related to 200m performance in young canoeists

ABSTRACT Traditionally, canoeing analyses have always been carried out by calculating mean values over a certain distance. However, a simple analysis of mean values in cyclic actions, such as canoe paddling, can lead to the loss of decisive data. Therefore, the objective of this study was to investigate whether the relationship between the periods of consecutive strokes can be an important aspect in all-out 200-m canoeing performance. A total of 22 young male canoeists aged 13.51 ± 0.43 years old voluntarily participated in the present study. Lateral recordings were taken from all participants when performing an all-out 200 m to subsequently analyse the kinematic variables of time, speed and cycle frequency, length and index. The time of each stroke was calculated by the frame differencesbetween two successive paddles. Likewise, short-term and long-term steadiness of consecutive strokes were analysed. Positive correlations were observed between all-out 200-m time and inter-stroke steadiness, identifying significant associations with long-term (r ≈ 0.8; p < 0.05) and short-term steadiness (r ≈ 0.7; p < 0.05). In conclusion, the present investigation defines and identifies inter-stroke steadiness as a new original kinematic variable that might be considered for performance analysis since it seems to be a key factor in all-out 200-m canoeing.

Effect of Wearing the Elevation Training Mask on Physiological Performance in Elite Kayaking Girls

Background: The elevation training mask 2.0 (ETM) has been introduced as a novel tool to allow for respiratory muscle training and altitude exposure during exercise that can improve performance and hematological markers in elite and well-trained athletes. Objectives: The purpose of the present study was to examine the effect of wearing ETM while performing exercise training on erythropoietin (EPO), vascular endothelial growth factor (VEGF), peak oxygen consumption (VO2max), lactate, and 1000-m kayaking performance in elite Kayaking girls. Methods: Thirty elite Kayaking girls (14 to 18-year-old) were equally and randomly assigned into mask, no mask, and control groups. The mask and no-mask groups completed 8 weeks of repeated sprint training, while the control group performed their routine kayaking training programs. Pre- and post-training tests included EPO, VEGF, VO2max, lactate, and 1000-m kayaking performance. Results: We showed that 1000-m time trial significantly decreased for mask (P &lt; 0.001) and control (P = 0.035) groups, and was significantly lower in mask group than control (P = 0.014) and no mask (P = 0.009) groups. EPO did not show any significant changes for all groups. VEGF was increased significantly for mask (P = 0.04) and no mask (P = 0.014) groups. Lactate was decreased significantly for mask group (P = 0.025). VO2max increased significantly for no mask group (P = 0.021). Conclusions: Performing repeated sprint training while wearing ETM has the potential to enhance performance in Kayak racing.

Eight Days of L-Citrulline or L-Arginine Supplementation Did Not Improve 200-m and 100-m Swimming Time Trials.

The effects of L-citrulline or L-arginine supplementation on exercise performance are equivocal, and the effects on swimming performance are unclear. We aimed to assess whether 8-day supplementation with L-arginine or L-citrulline supplementation would improve 200 m and 100 m freestyle swimming time-trial performances. After the baseline trial (first visit), in a double-blind, randomised design, 15 trained/developmental (5 females) swimmers and triathletes were assigned to three groups and underwent an 8-day supplementation period, with a daily dose of either 8 gr L-arginine (Arg, n = 5) or L-citrulline (Cit, n = 5) or placebo (Pla, n = 5). On day 9, participants completed experimental trial (second visit). In each trial, after blood sampling, participants performed both 200 m and 100 m freestyle swimming time-trials, with 30 min recovery between trials. Plasma nitric oxide (NOx) and blood lactate concentrations (BLa) were collected immediately before and after 200 m and 100 m TTs, respectively. No significant difference was observed in NOx between groups (p = 0.201). There was no significant difference in 200 m (p = 0.226) and 100 m swimming time-trials (p = 0.993) between groups. There was a main effect of time on BLa concentration (p < 0.001), but no trial × group (p = 0.243) and trial × lactate × group interaction effect (p = 0.276) was present. Furthermore, 8-day either L-citrulline or L-arginine supplementation did not enhance middle (200 m) and short-distance (100 m) swimming performance in trained/developmental swimmers and triathletes. These findings do not support the use of L-citrulline or L-arginine supplementation as ergogenic aids for swimming performance.

Muscle mitochondrial energetics predicts mobility decline in well-functioning older adults: The baltimore longitudinal study of aging.

BackgroundMuscle mitochondrial dysfunction is associated with poor mobility in aging. Whether mitochondrial dysfunction predicts subsequent mobility decline is unknown.MethodsWe examined 380 cognitively normal participants aged 60 and older (53%women, 22%Black) who were well‐functioning (gait speed ≥ 1.0 m/s) and free of Parkinson's disease and stroke at baseline and had data on baseline skeletal muscle oxidative capacity and one or more mobility assessments during an average 2.5 years. Muscle oxidative capacity was measured by phosphorus magnetic resonance spectroscopy as the post‐exercise recovery rate of phosphocreatine (kPCr). Mobility was measured by four walking tests. Associations of baseline kPCr with mobility changes were examined using linear mixed‐effects models, adjusted for covariates. In a subset, we examined whether changes in muscle strength and mass affected these associations by adjusting for longitudinal muscle strength, lean mass, and fat mass.ResultsLower baseline kPCr was associated with greater decline in all four mobility measures (β, p‐value: (0.036, 0.020) 6‐m usual gait speed; (0.029, 0.038) 2.5‐min usual gait speed; (0.034, 0.011) 6‐m rapid gait speed; (−0.042, <0.001) 400‐m time). In the subset, further adjustment for longitudinal muscle strength, lean mass, and fat mass attenuated longitudinal associations with changes in mobility (Δβ reduced 26–63%).ConclusionAmong initially well‐functioning older adults, worse muscle mitochondrial function predicts mobility decline, and part of this longitudinal association is explained by decline in muscle strength and mass. Our findings suggest that worse mitochondrial function contributes to mobility decline with aging. These findings need to be verified in studies correlating longitudinal changes in mitochondrial function, muscle, and mobility performance.

Knee Flexor Eccentric Strength, Hamstring Muscle Volume and Sprinting in Elite Professional Soccer Players with a Prior Strained Hamstring.

Simple SummaryGiven the link between a prior hamstring injury and the increased risk of suffering a subsequent injury in professional soccer, an understanding of the features displayed by previously injured players is important. The aim of the present study was to investigate if players with a history of hamstring injury exhibit bilateral deficits in knee flexor eccentric strength, hamstring muscle volume, and sprinting performance. The eccentric knee flexor strength was greater in the previously injured limbs compared to both the contralateral uninjured limbs in the previously injured group and the uninjured limbs in the previously uninjured players. Previously injured limbs showed possibly larger short heads of the biceps femoris and likely semitendinosus muscle volumes. Sprinting performances in the 5-m were possibly worse in players with a history of hamstring muscle strain injury compared to the previously uninjured players.The aim was to determine if players with a prior hamstring strain injury (HSI) exhibit bilateral deficits in knee flexor eccentric strength and hamstring muscle volume and differences in sprinting performance compared with players without a history of HSIs. Forty-six male professional soccer players participated in this study. Eccentric knee flexor strength, hamstring muscle volume (MRI), and a 20-m running sprint test (5- and 10-m split time) were assessed at the start of the preseason. Eccentric knee strength of the previously injured limbs of injured players was greater (ES: 1.18–1.36) than the uninjured limbs in uninjured players. Previously injured limbs showed possibly larger biceps femoris short heads (BFSh) and likely semitendinosus (ST) muscle volumes than the contralateral uninjured limbs among the injured players (ES: 0.36) and the limbs of the uninjured players (ES: 0.56), respectively. Players who had experienced a previous HSI were possibly slower in the 5-m (small ES: 0.46), while unclear differences were found in both the 10-m and 20-m times. Players with a prior HSI displayed greater eccentric knee flexor strength, possibly relatively hypertrophied ST and BFSh muscles, and possibly reduced 5-m sprinting performances than previously uninjured players. This can have implication for the design of secondary hamstring muscle injury prevention strategies.

Three weeks of combined resisted and assisted in-water training for adolescent sprint backstroke swimming: a case study

PurposeResisted and assisted in-water training methods are often employed in swimming training but their effectiveness remains unsubstantiated for different strokes and age groups. The study aim was to quantify the effects of a 3-week combined assisted and resisted in-water training program on 50- and 100-m adolescent backstroke performance.MethodsIn addition to regular swimming training, 9 (5 male, 4 female; age: 15.4 ± 1.7 years; 50-m backstroke FINA points: 346 ± 142) competitive backstroke swimmers performed a combined in-water machine-resisted and bungee-assisted training program 3 days/week with 3 resisted and 3 assisted 25-m sprints per session. Before and after the 3-week training, 50- and 100-m backstroke time trials were undertaken, with stroke rate, heart rate, and rating of perceived exertion collected.ResultsThere was a significant small improvement in 100-m backstroke times (3.4 ± 3.4% faster; ES = 0.27, p &lt; 0.01), but only a trivial improvement in 50-m backstroke times (1.0 ± 3.1% faster; ES = 0.07, p = 0.19). Females had substantially greater improvements than males in both 50-m (2.4 ± 2.7% faster vs. –0.2 ± 3.2% slower) and 100-m (5.1 ± 2.6% faster vs. 2.0 ± 3.5% faster) backstroke time trials, but with the small sample size, this warrants further investigation.ConclusionsWe demonstrated that adding a 3-week combined in-water resisted and assisted training was likely more beneficial for the longer 100-m distance; females seemed to benefit more than males.

Assessment of the frequency of tarsal tunnel syndrome in rheumatoid arthritis.

Objectives In this study, we aimed to determine the frequency of tarsal tunnel syndrome (TTS) in rheumatoid arthritis (RA) patients. Patients and methods Thirty RA patients (1 male, 29 females; mean age: 41.9±10.1 years; range, 26 to 65 years) who met the American College Rheumatology (ACR) classification criteria and 20 healthy volunteers (1 male, 19 females; mean age: 39.3±10.8 years; range, 26 to 60 years) without any complaints between August 2006 and October 2007 were included in the study. Demographic characteristics of the study group were assessed and neurological examinations were performed. The Tinel’s sign was checked to provoke the TTS symptoms. Disease severity was measured using Visual Analog Scale (VAS), Disease Activity Score-28 (DAS28), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). The health-related quality of life and disability status were determined using the Health Assessment Questionnaire (HAQ), Short Form 36 (SF-36), Foot Function Index (FFI), and VAS (0-100 mm). The positional relationship of the foot pain was questioned with VAS. The 100-m walking distance of the patient and control groups were calculated. Results Bilateral TTS was detected in 10 of the patients (33.3%) with rheumatoid arthritis. No relationship with the TTS disease duration, seropositivity, rheumatoid nodule, joint deformities, corticosteroid use, and DAS28 score were found. In correlation with TTS, foot and ankle joint were the first involved joints at the beginning of RA disease (p<0.005). The Tinel’s sign was found to be 45% positive in patients with TTS. The 100-m walking time was significantly longer in RA patients compared to the control group (p<0.0001). Conclusion Tarsal tunnel syndrome is commonly seen in RA and its incidence increases in patients with primary foot involvement. Therefore, caution should be taken against the entrapment neuropathies in these patients, and they should be supported by electrophysiological practices, when the diagnosis is necessary.

Passive and active muscle elasticity of medial gastrocnemius is related to performance in sprinters.

Limited information is available on the association between muscle material properties and sprint performance. We aimed to identify whether and how the elasticity of passive and active muscle of the medial gastrocnemius (MG) is related to sprint performance. MG shear wave speed was measured under passive and active (20%, 50%, 80% of maximal voluntary contraction [MVC]) conditions, with ultrasound shear wave elastography, in 18 male sprinters. Passive and active ankle joint stiffness was assessed by applying a short-range fast stretch during 0%, 20%, 50%, and 80% MVC of plantar flexion. Additionally, rate of torque development (RTD) during explosive plantar flexion was measured. Passive and active MG shear wave speed was negatively correlated with 100-m race time. Passive MG shear wave speed was positively correlated with RTD, and RTD was negatively correlated with 100-m race time. MG shear wave speed at 50% and 80% MVC showed a positive correlation with ankle joint stiffness at the corresponding contraction level, and ankle joint stiffness at 50% and 80% MVC showed negative correlations with 100-m race time. These correlations were significant even after controlling for MVC torque. Our findings indicate that passive and active muscle elasticity of plantar flexor is important to achieve superior sprint performance. Specifically, high elasticity of passive MG could be related to superior sprint performance through high explosive torque production. In contrast, high elasticity of active MG at moderate-to-high intensity is likely related to high sprint performance through high ankle joint stiffness.

Transcranial Direct Current Stimulation Does Not Affect Sprint Performance or the Horizontal Force-Velocity Profile

ABSTRACT Purpose: The aim of this study was to explore the effects of transcranial direct current stimulation (tDCS) on sprint performance and the horizontal force-velocity (F-v) profile. Method: Thirty-two healthy subjects (25 men and 7 women; age = 21.8 ± 2.4 years) completed three sessions separated by 1 week following a double-blinded crossover design. Each session consisted of two maximal sprints of 30 meters that were performed after applying ANODAL, CATHODAL or SHAM tDCS over the left dorsolateral prefrontal cortex (DLPFC) for 15 minutes at 2 mA. The 30-m time and the horizontal F-v profile variables (theoretical maximal force [F 0], theoretical maximal velocity, Fv slope, maximal power [Pmax], decrease in the ratio of horizontal-to-resultant force, and maximal ratio of horizontal-to-resultant force) were compared between the tDCS conditions. Results: No significant differences between the tDCS conditions were observed for any variable (p range = 0.061 to 0.842). The magnitude of the differences was negligible for most of the comparisons (effect size [ES] < 0.20) with the only exception of Pmax and F 0 which were greater for the ANODAL compared to the SHAM condition (both ES = 0.20). Conclusions: The application of tDCS over the DLPFC is not effective to increase non-fatigued sprint performance.

The relationship between vertical jump performance during different training periods and results of 200m-sprint

Background: The purpose of the current study was to investigate: (1) differences between three types of countermovement jumps (CMJ), (2) development of lower-body strength during training periods, and (3) relationship between 200m personal best results and jumping ability in sprinters. Material and methods: A total of 14 male sprinters from local university academic sport club participated in the study. Athletes performed three variants of CMJ: with arm swing (AS), without AS, and from a maximal squat position. We took measures two times: during the active rest period and the final phase of the preparatory period. For measurements the Optojump photoelectric cell system was used. Statistical significance was set at p ≤ 0.05. Results: Effect of the training period and jump variant was shown on all jump parameters (height, total energy, and specific energy; p&lt;0.001). Personal best 200m time was significantly correlated only with total energy in both training periods in all jump variants. Conclusions: According to the results obtained in this study, we conclude that: (1) jumping parameters depends on CMJ variants, (2) jumping abilities improved during sprinter training, (3) 200m-sprint PB are related to total energy, but not with specific energy and jump height.

Effect of three different set-up conditions on the propulsive force measures, reliability, and ecological validity during front crawl tethered-swimming

ABSTRACT This study analysed the effect of three set-up conditions on the propulsive force (PF) measures, test–retest reliability, and ecological validity during front crawl tethered-swimming (TS). Twenty-five (20.3 ± 3.7 years) swimmers performed TS in three conditions: Slp0 (0º of cable slope), Slp10 (10º of slope) and Slp20 (20º of slope), in two sessions. The second session included a 50-m performance and a questionnaire on the similarity of TS and free-swimming and overall comfort. Peak, mean force, impulse and force development rate, 50-m time and mean velocity, similarity scores and comfort were analysed. Effect of TS condition (p < 0.001) was observed for peak, mean force and force development rate. Regardless of the condition, reliability ranged from good to excellent (ICC = 0.79–0.95) and correlations with performance time (r≥-0.7) and mean velocity (r ≥ 0.63) were significant for all PF variables. The similarity between TS and free-swimming, and overall comfort as perceived by the swimmers, did not differ between conditions. Set-up condition influences the measures of PF in front-crawl TS. All conditions are reliable and present similar associations between PF and performance. Ecological validity indicators were near to the halfway point of the measurement scales independently of the condition.

Lumbar discectomies in elite rowers: presentation, operative treatment, and return to play

ABSTRACT Objective In a cohort of elite rowers requiring lumbar spine surgery, we report information regarding: (1) presentation, (2) operative treatment, and (3) return to play (RTP). Methods All competitive rowers undergoing spine surgery at a single academic institution from 2015 to 2020 were analyzed. Three rowers underwent spine surgery during the allotted time period. Demographic, clinical, operative, and RTP data was recorded. Each athlete’s self-reported level of effort/performance was assessed before and after surgery. First RTP was defined as the time of initial return to rowing activities, and full RTP was defined as the time of unrestricted return to rowing activities. Descriptive statistics were performed. Results The three collegiate rowers ranged from 20- to 21-year-old, each with L5/S1 disc herniations. Preoperative pain levels ranged from 8 to 10, and inciting injury events included back squats, front squats, and rowing during the ‘finish’ stage. Each athlete underwent a minimally invasive, unilateral L5/S1 decompression, partial medial facetectomy, and partial discectomy with microscopic-assistance. First RTP ranged from 4-6 months, with full RTP at 6–8 months. Pain dissipated to the 0–1 range at full RTP. Final effort/performance improved from 10–60% mid-injury to 90–100% at full RTP. Each athlete’s 2000m row time showed a decline mid-injury and an improvement to at or within 10 s of their pre-injury time. Conclusions Drawing from three collegiate rowers who underwent lumbar decompression surgery, each athlete successfully returned to rowing, with initial RTP in the 4–6 months range and full RTP in the 6–8 months range. Performance levels rebounded to near or better than pre-injury performance. The results of this small case series warrant replication in larger, multi-institutional samples.

Determinants of Performance in Paced and Maximal 800-m Running Time Trials.

We aimed to identify the underpinning physiological and speed/mechanical determinants of different types of 800-m running time trials (i.e., with a positive or negative pacing strategy) and key components within each 800-m time trial (i.e., first and final 200 m). Twenty trained male 800-m runners (800-m personal best time (min:s): 1:55.10 ± 0:04.44) completed a maximal 800-m time trial (800MAX) and one pacing trial, whereby runners were paced for the first lap, and speed was reduced by 7.5% (800PACE) relative to 800MAX, whereas the last lap was completed in the fastest time possible. Anaerobic speed reserve, running economy, the velocity corresponding with V˙O2peak (VV˙O2peak), maximal sprint speed (MAXSS), maximal accumulated oxygen deficit, and sprint force-velocity-power profiles were derived from laboratory and field testing. Carnosine content was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus and expressed as a carnosine aggregate Z (CAZ) score to estimate muscle typology. Data were analyzed using multiple stepwise regression analysis. MAXSS and vV˙O2peak largely explained the variation in 800MAX time (r2 = 0.570; P = 0.020), whereas MAXSS was the best explanatory variable for the first 200-m time in 800MAX (adjusted r2 = 0.661, P < 0.001). Runners with a higher CAZ score (i.e., higher estimated percentage of type II fibers) reduced their last lap time to a greater extent in 800PACE relative to 800MAX (adjusted r2 = 0.413, P < 0.001), whereas better maintenance of mechanical effectiveness during sprinting, a higher CAZ score and vV˙O2peak was associated with a faster final 200-m time during 800PACE (adjusted r2 = 0.761, P = 0.001). These findings highlight that diversity in the physiological and speed/mechanical characteristics of male middle-distance runners may be associated with their suitability for different 800-m racing strategies to have the best chance of winning.

Predicting performance in 4 x 200-m freestyle swimming relay events.

The aim was to predict and understand variations in swimmer performance between individual and relay events, and develop a predictive model for the 4x200-m swimming freestyle relay event to help inform team selection and strategy. Race data for 716 relay finals (4 x 200-m freestyle) from 14 international competitions between 2010-2018 were analysed. Individual 200-m freestyle season best time for the same year was located for each swimmer. Linear regression and machine learning was applied to 4 x 200-m swimming freestyle relay events. Compared to the individual event, the lowest ranked swimmer in the team (-0.62 s, CI = [-0.94, -0.30]) and American swimmers (-0.48 s [-0.89, -0.08]) typically swam faster 200-m times in relay events. Random forest models predicted gold, silver, bronze and non-medal with 100%, up to 41%, up to 63%, and 93% sensitivity, respectively. Team finishing position was strongly associated with the differential time to the fastest team (mean decrease in Gini (MDG) when this variable was omitted = 31.3), world rankings of team members (average ranking MDG of 18.9), and the order of swimmers (MDG = 6.9). Differential times are based on the sum of individual swimmer's season's best times, and along with world rankings, reflect team strength. In contrast, the order of swimmers reflects strategy. This type of analysis could assist coaches and support staff in selecting swimmers and team orders for relay events to enhance the likelihood of success.

Effects of forearm wearable resistance during accelerated sprints: From a standing start position

ABSTRACT Fusiform weighted garments enable specific loading strategies during sport-specific movements. Loading the arms over during accelerated sprinting from a 2-point start position is pertinent to a variety of sporting performances. Fourteen sprint-trained individuals (age = 20.61 ± 1.16 years; height = 1.73 m ± 3.85 cm; body mass 65.33 ± 4.86 kg; personal best 100-m race time 11.40 ± 0.39 s) performed unloaded/loaded wearable resistance (WR) sprints. Between-condition step kinematics and kinetics were compared over four acceleration phases: steps 1–4, 5–8, 9–12 and 13–16. Sprint performance did not differ between unloaded and loaded WR at 10-m (−1.41%; ES = −0.32), or 30-m (−0.76%; ES = −0.24). Sprinting with forearm WR significantly decreased step frequency during phase two (p < 0.05, −3.42%; ES = −0.81) and three (−3.60%; ES = −0.86) and step velocity during phase four of the 30 m sprinting task (p < 0.05, −3.61%; ES: 0.91) only. There were no significant differences (p ≤ 0.05) between step kinetics amongst the two conditions. Findings indicate that arm-loaded WR may provide specific sprinting overload for 2-point starting positions. This may be relevant to a wider sporting context such as field and team sport performances.

GIS based Vs30, Vsz &amp; Dbed rock Mapping for the Shallow Sites of Islamabad, Pakistan

The location of Pakistan is in a collision zone among the Eurasian and Indian plate boundaries. The geological framework of the Northwest Himalaya makes Northern Pakistan susceptible to frequent moderate to major earthquakes. The devastating earthquake of October 8, 2005 caused 87,000 deaths, 2.8 million displacements and financial loss of 200 Billion USD equivalent to 6% GDP of Pakistan. Islamabad is in seismically active region, the studies conducted for this region addresses the poor soil conditions, non-engineering construction practices and high level of seismic shaking. However, none of these studies provided readily available ground maps (top 30m time average shear wave velocity V s30 , average soil shear wave velocity V sz &amp; depth to bed rock D bed rock ) based on site specific geotechnical database. V s30 , V sz &amp; D bed rock are important parameters for the evaluation of dynamic site characteristics of shallow bed rock sites. In Pakistan, Uniform Building Code (UBC-1997) is currently practiced, and the site classification are defined using site specific V s30 . In this study, geotechnical borehole database of 57 sites of Islamabad was collected to develop GIS based V s30 , V sz &amp; D bed rock maps using Standard Penetration Test value (SPT-N). The borehole database includes, SPT-N, soil description and unit weight of soil for the Islamabad sites. In order to develop shear wave velocity (V s ) profiles, the available V s -SPT empirical correlations were evaluated where both SPT-N &amp; V s measured data is available. The selected available correlations were applied to SPT-N database to develop representative Vs profiles. Using these V s profiles, V s30 , V sz &amp; D bed rock GIS based maps were developed by applying Kriging interpolation in open source QGIS software. The proposed GIS maps can be used in preliminary earthquake design for seismic resilient earthquake design in Islamabad, Pakistan.

GIS based Vs30, Vsz &amp; Dbed rock Mapping for the Shallow Sites of Islamabad, Pakistan

The location of Pakistan is in a collision zone among the Eurasian and Indian plate boundaries. The geological framework of the Northwest Himalaya makes Northern Pakistan susceptible to frequent moderate to major earthquakes. The devastating earthquake of October 8, 2005 caused 87,000 deaths, 2.8 million displacements and financial loss of 200 Billion USD equivalent to 6% GDP of Pakistan. Islamabad is in seismically active region, the studies conducted for this region addresses the poor soil conditions, non-engineering construction practices and high level of seismic shaking. However, none of these studies provided readily available ground maps (top 30m time average shear wave velocity V s30 , average soil shear wave velocity V sz &amp; depth to bed rock D bed rock ) based on site specific geotechnical database. V s30 , V sz &amp; D bed rock are important parameters for the evaluation of dynamic site characteristics of shallow bed rock sites. In Pakistan, Uniform Building Code (UBC-1997) is currently practiced, and the site classification are defined using site specific V s30 . In this study, geotechnical borehole database of 57 sites of Islamabad was collected to develop GIS based V s30 , V sz &amp; D bed rock maps using Standard Penetration Test value (SPT-N). The borehole database includes, SPT-N, soil description and unit weight of soil for the Islamabad sites. In order to develop shear wave velocity (V s ) profiles, the available V s -SPT empirical correlations were evaluated where both SPT-N &amp; V s measured data is available. The selected available correlations were applied to SPT-N database to develop representative Vs profiles. Using these V s profiles, V s30 , V sz &amp; D bed rock GIS based maps were developed by applying Kriging interpolation in open source QGIS software. The proposed GIS maps can be used in preliminary earthquake design for seismic resilient earthquake design in Islamabad, Pakistan.

Kinematic factors associated with start performance in World-class male sprinters

The aim was to investigate the kinematic factors associated with successful performance in the initial acceleration phase of a sprint in the best male athletes in the World at the 2018 World Indoor Athletics Championships. High speed video (150 Hz) was captured for eight sprinters in the men’s 60 m final. Spatio-temporal and joint kinematic variables were calculated from the set position to the end of the first ground contact post-block exit (GC1). Normalised average horizontal external power (NAHEP) defined performance and was the dependent variable for a series of regression analyses. Clear relationships were found between GC1 NAHEP and 10-m time, 60-m time, change in velocity, acceleration and contact time in the first ground contact (r = –0.74, –0.64, 0.96, 0.91 and –0.56, respectively). Stepwise multiple linear regression of joint kinematic variables in the first ground contact revealed that trunk angle at take-off and thigh separation angle at take-off explained nearly 90% of variation in GC1 NAHEP (R2 = 0.89). The athletes’ projection at take-off with a forward leaning trunk and large thigh separation is characteristic therefore of excellent initial acceleration performance and this will be a good visual guide for technical coaching instruction. This was the first study of its kind to adopt such a research design in a World-class sample in a representative environment. Future studies that combine detailed kinematic and kinetic data capture and analysis in such a setting will add further insight to the findings of this investigation.

Lower volume throughout the taper and higher intensity in the last interval session prior to a 1500m time trial improves performance.

Eight highly trained middle-distance runners (1500m personal best 4:01.4± 0:09.2min) completed two 7-day tapers, separated by at least 3 weeks of regular training: (i) prescribed using prediction models from elite middle-distance runners, where continuous running volume was reduced by 30% and interval intensity was equal to 1500m race pace (RP); and (ii) continuous running volume was reduced by 60% and intensity of the final interval session was completed at 110% of 1500m race pace (HI). Performance was assessed using 1500m time trials on an indoor 200m track 1 day before, and 1 day after each taper. Performance time was improved after HI by 5.2± 3.7s (mean± 90% confidence limits, p= 0.03) and by 3.2± 3.8s after RP (p= 0.15). The first and second 300m segments of the 1500m time trial were faster post-taper in RP (p= 0.012 and p= 0.017, respectively) and HI (both p= 0.012). Running faster than race pace late in a low-volume taper is recommended to improve 1500m track performance. A positive pacing strategy is adopted after tapering, although care should be taken to avoid an over-fast start. Novelty: A large reduction in volume during tapering and an increase in final interval session intensity improves running performance. Athletes adopt a negative pacing strategy before tapering and a positive-pacing strategy after tapering.