Prolonged Running Research Articles

The Validity and Contributing Physiological Factors to 30-15 Intermittent Fitness Test Performance in Rugby League

Scott, TJ, Duthie, GM, Delaney, JA, Sanctuary, CE, Ballard, DA, Hickmans, JA, and Dascombe, BJ. The validity and contributing physiological factors to 30-15 intermittent fitness test performance in rugby league. J Strength Cond Res 31(9): 2409-2416, 2017-This study examined the validity of the 30-15 Intermittent Fitness Test (30-15IFT) within rugby league. Sixty-three Australian elite and junior-elite rugby league players (22.5 ± 4.5 years, 96.1 ± 9.5 kg, Σ7 skinfolds: 71.0 ± 18.7 mm) from a professional club participated in this study. Players were assessed for anthropometry (body mass, Σ7 skinfolds, lean mass index), prolonged high-intensity intermittent running (PHIR; measured by 30-15IFT), predicted aerobic capacity (MSFT) and power (AAS), speed (40 m sprint), repeated sprint, and change of direction (COD-505 agility test) ability before and after an 11-week preseason training period. Validity of the 30-15IFT was established using Pearson's coefficient correlations. Forward stepwise regression model identified the fewest variables that could predict individual final velocity (VIFT) and change within 30-15IFT performance. Significant correlations between VIFT and Σ7 skinfolds, repeated sprint decrement, V[Combining Dot Above]O2maxMSFT, and average aerobic speed were observed. A total of 71.8% of the adjusted variance in 30-15IFT performance was explained using a 4-step best fit model (V[Combining Dot Above]O2maxMSFT, 61.4%; average aerobic speed, 4.7%; maximal velocity, 4.1%; lean mass index, 1.6%). Across the training period, 25% of the variance was accounted by ΔV[Combining Dot Above]O2maxMSFT (R = 0.25). These relationships suggest that the 30-15IFT is a valid test of PHIR within rugby league. Poor correlations were observed with measures of acceleration, speed, and COD. These findings demonstrate that although the 30-15IFT is a valid measure of PHIR, it also simultaneously examines various physiological capacities that differ between sporting cohorts.

Effects of prolonged running in the heat and cool environments on selected physiological parameters and salivary lysozyme responses

IntroductionLysozyme is one of the salivary antimicrobial proteins which act as the “first line of defence” at the mucosal surface. The effects of prolonged exercise in the hot and cool environments among recreational athletes on salivary lysozyme responses are very limited in the literature, especially in the Asian countries. ObjectiveTo determine the effects of prolonged running in the hot and cool environments on selected physiological parameters and salivary lysozyme responses among recreational athletes. MethodsRandomised and cross-over study design. Thirteen male recreational athletes (age: 20.9 ± 1.3 years old) from Universiti Sains Malaysia participated in this study. They performed two separate running trials; 90 min running at 60% of their respective maximum oxygen uptake (V˙O2max) One running trial was performed in the hot (31ºC) while the other was in the cool (18ºC) environment and this sequence was randomised. Each running trial was started with a 5 min warm-up at 50% of participant's respective V˙O2max Recovery period between these two trials was one week. In the both trials, saliva samples, blood samples, heart rate, ratings of perceived exertion, skin and tympanic temperatures, oxygen consumption, nude body weight, room temperature, and relative humidity were collected. ResultsParticipants' skin temperature, tympanic temperature, body weight changes, heart rate, ratings of perceived exertion, and plasma volume changes were significantly higher (p < 0.05) in the hot trial compared to the cool trial. Saliva flow rate was not significantly (p = 0.949) different between the hot (0.32 ± 0.08 ml/min) and cool (0.27 ± 0.05 ml/min) trials. However, in each trial, it significantly decreased (p < 0.05) at post-exercise as compared to pre-exercise but it returned to baseline value at 1 h post-exercise. In addition, there were no significant differences between and within hot and cool trials in salivary lysozyme concentration (p = 0.925; 4.79 ± 1.37 and 4.44 ± 1.11 μg/ml respectively) and secretion rate (p = 0.843; 1.67 ± 1.1 and 1.17 ± 1.0 μg/min respectively). ConclusionThis study found similar lysozyme responses between both hot and cool trials. Thus, room/ambient temperature did not affect lysozyme responses among recreational athletes. Nevertheless, the selected physiological parameters were significantly affected by room temperature.

Arsenic loss during metallurgical processing of arsenical bronze

The chemical composition of ancient copper-based metal changes over time due to repetitive recycling and mixing of old metal. Prehistoric copper usually contains impurities from the copper ores themselves, and some have been used as evidence of anthropomorphically induced chemical change. Research into these changes has historically relied upon the assumption of element loss linearity, which is highly misleading and in fact varies with a multitude of factors. To illustrate the complexity of such losses for prehistoric alloys, we have selected arsenical bronze (Cu-As alloys) for study. The mass loss of several Cu-As-alloys under reducing atmosphere was measured by DTA/TGA. From our comparison of the experimental results to thermodynamic calculations and literature data, it was unclear whether weight losses were solely caused by the elemental loss of arsenic. However, a prolonged time temperature-cycling run demonstrated that mainly arsenic volatilizes; hence, the non-linear mass loss from the alloy can be directly attributed to arsenic.

Depletion of Pax7+ satellite cells does not affect diaphragm adaptations to running in young or aged mice.

Satellite cell depletion does not affect diaphragm adaptations to voluntary wheel running in young or aged mice. Satellite cell depletion early in life (4months of age) has minimal effect on diaphragm phenotype by old age (24months). Prolonged satellite cell depletion in the diaphragm does not result in excessive extracellular matrix accumulation, in contrast to what has been reported in hind limb muscles. Up-regulation of Pax3 mRNA+ cells after satellite cell depletion in young and aged mice suggests that Pax3+ cells may compensate for a loss of Pax7+ satellite cells in the diaphragm. Future investigations should focus on the role of Pax3+ cells in the diaphragm during adaptation to exercise and ageing. Satellite cell contribution to unstressed diaphragm is higher compared to hind limb muscles, which is probably attributable to constant activation of this muscle to drive ventilation. Whether satellite cell depletion negatively impacts diaphragm quantitative and qualitative characteristics under stressed conditions in young and aged mice is unknown. We therefore challenged the diaphragm with prolonged running activity in the presence and absence of Pax7+ satellite cells in young and aged mice using an inducible Pax7CreER -R26RDTA model. Mice were vehicle (Veh, satellite cell-replete) or tamoxifen (Tam, satellite cell-depleted) treated at 4months of age and were then allowed to run voluntarily at 6months (young) and 22months (aged). Age-matched, cage-dwelling, Veh- and Tam-treated mice without wheel access served as activity controls. Diaphragm muscles were analysed from young (8months) and aged (24months) mice. Satellite cell depletion did not alter diaphragm mean fibre cross-sectional area, fibre type distribution or extracellular matrix content in young or aged mice, regardless of running activity. Resting in vivo diaphragm function was also unaffected by satellite cell depletion. Myonuclear density was maintained in young satellite cell-depleted mice regardless of running, although it was modestly reduced in aged sedentary (-7%) and running (-19%) mice without satellite cells (P<0.05). Using fluorescence in situ hybridization, we detected higher Pax3 mRNA+ cell density in both young and aged satellite cell-depleted diaphragm muscle (P<0.05), which may compensate for the loss of Pax7+ satellite cells.

Effect of sodium bicarbonate on prolonged running performance: A randomized, double-blind, cross-over study.

BackgroundThe ability to sustain intense exercise seems to be partially limited by the body’s capability to counteract decreases in both intra- and extracellular pH. While the influence of an enhanced buffering capacity via sodium bicarbonate (BICA) on short-term, high-intensity exercise performance has been repeatedly investigated, studies on prolonged endurance performances are comparatively rare, especially for running. The aim of the following study was to assess the ergogenic effects of an oral BICA substitution upon exhaustive intensive endurance running performance.MethodIn a double-blind randomized cross-over study, 18 trained runners (VO2peak: 61.2 ± 6.4 ml•min-1•kg-1) performed two exhaustive graded exercise tests and two constant load tests (30 main at 95% individual anaerobic threshold (IAT) followed by 110% IAT until exhaustion) after ingestion of either sodium bicarbonate (BICA) (0.3 g/kg) or placebo (4 g NaCl) diluted in 700 ml of water. Time to exhaustion (TTE) in the constant load test was defined as the main outcome measure. Throughout each test respiratory gas exchange measurements were conducted as well as determinations of heart rate, blood gases and blood lactate concentration.ResultsTTE in the constant load test did not differ significantly between BICA and placebo conditions (BICA: 39.6 ± 5.6 min, placebo: 39.3 ± 5.6 min; p = 0.78). While pH in the placebo test dropped to a slightly acidotic value two minutes after cessation of exercise (7.34 ± 0.05) the value in the BICA trial remained within the normal range (7.41 ± 0.06) (p < 0.001). In contrast, maximum running speed (Vmax) in the exhaustive graded exercise test was significantly higher with BICA (17.4 ± 1.0 km/h) compared to placebo (17.1 ± 1.0 km/h) (p = 0.009). The numerical difference in maximum oxygen consumption (VO2peak) failed to reach statistical significance (BICA: 61.2 ± 6.4 ml•min-1•kg-1, placebo: 59.8 ± 6.4 ml•min-1•kg-1; p = 0.31). Maximum blood lactate was significantly higher with BICA compared to the corresponding placebo test (BICA: 11.1 ± 2.3 mmol/l, placebo: 8.9 ± 3.0 mmol/l; p < 0.001). At the end of exercise, an acidotic pH value was found in both exhaustive graded exercise tests (p = 0.002). BICA caused gastrointestinal side effects in 15 patients.ConclusionMaximal performance was enhanced significantly after BICA administration. The ergogenic effect of BICA in the exhaustive graded exercise test can most likely be attributed to an increased anaerobic glycolysis that is reflected by an accumulation of lactate. However, TTE in prolonged high-intensity running was not improved. Even at the end of exercise no severe metabolic acidosis was found. Metabolic acidification as one of the dominant factors causing muscular fatigue should therefore be reconsidered.Trial registrationGerman Clinical Trials Register (DRKS) DRKS00011284.

Effects of bee propolis supplementation on Lysozyme and lactoferrin responses following prolonged running in recreational Athletes

Effects of bee propolis supplementation on Lysozyme and lactoferrin responses following prolonged running in recreational Athletes

Prolonged running increases knee moments in sidestepping and cutting manoeuvres in sport

ObjectivesTo investigate how knee kinematics, kinetics and loading changes during sidestepping tasks following a prolonged running protocol performed in a laboratory setting. DesignAll participants performed sidestepping, and crossover cutting tasks in a randomised order before and after a 60min running protocol on a non-motorised treadmill that simulated an AF game. MethodsEight healthy male participants who partook in semi-professional and amateur Australian Football undertook a series of straight line runs, sidestepping (SS), and crossover cutting (XO) tasks before and after a simulated game of Australian football. Kinematic data were analysed at initial foot contact of the SS and XO manoeuvres and kinetic data were analysed during the weight acceptance phase of the stance. ResultsThe knee was significantly more flexed at foot contact following fatigue compared to pre-fatigue states. Fatigue was also a factor contributing to significant increases in internal knee extension moments. Significant differences were also observed between SS and XO trials with flexion/extension moments, with notable differences in varus/valgus and internal/external rotation moments. ConclusionsAcute angles of knee flexion at foot strike in a fatigued state may place the joint at an increased risk of injury. Increases in knee extension moments in the fatigued state suggests the knee joint must withstand significantly high stresses once fatigued.

Fatigue-induced dissociation between rate of force development and maximal force across repeated rapid contractions

We examined whether the presence of fatigue induced by prolonged running influenced the time courses of force generating capacities throughout a series of intermittent rapid contractions. Thirteen male amateur runners performed a set of 15 intermittent isometric rapid contractions of the knee extensor muscles, (3s/5s on/off) the day before (PRE) and immediately after (POST) a half marathon. The maximal voluntary contraction force, rate of force development (RFDpeak), and their ratio (relative RFDpeak) were calculated. At POST, considering the first (out of 15) repetition, the maximal force and RFDpeak decreased (p<0.0001) at the same extent (by 22±6% and 24±22%, respectively), resulting in unchanged relative RFDpeak (p=0.6). Conversely, the decline of RFDpeak throughout the repetitions was more pronounced at POST (p=0.02), thus the decline of relative RFDpeak was more pronounced (p=0.007) at POST (−25±13%) than at PRE (−3±13%). The main finding of this study was that the fatigue induced by a half-marathon caused a more pronounced impairment of rapid compared to maximal force in the subsequent intermittent protocol. Thus, the fatigue-induced impairment in rapid muscle contractions may have a greater effect on repeated, rather than on single, attempts of maximal force production.

Running momentum: a new method to quantify prolonged high-intensity intermittent running performance in collision sports

ABSTRACTPurpose: This study determined differences in prolonged high-intensity running (PHIR) performance and running momentum (pIFT) between competition levels and positional groups in rugby league.Methods: Elite Australian National Rugby League (NRL), sub-elite [state-based competition (SRL); National Youth Competition (NYC); local league (LL)] and junior-elite (U18; U16) rugby league players completed the 30–15 Intermittent Fitness Test (30–15IFT) to quantify PHIR performance. Final running momentum (pIFT; kg·m∙s−1) was calculated as the product of body mass and final running velocity (VIFT; m∙s−1). Effect sizes (ESs) were used to examine between-group differences.Results: 30–15IFT performance was possibly to likely higher in NRL players (19.5 ± 1.0 km·h−1; mean ± SD) when compared with SRL (ES = 0.6 ± 0.5; ES ± CI), NYC (ES = 0.6 ± 0.5) and U18 (ES = 0.8 ± 0.5) players. NRL players (537 ± 41 kg·m·s−1) possessed possibly to very likely greater pIFT than SRL (ES = 0.7 ± 0.5), NYC (ES = 1.2 ± 0.5), U18 (ES = 2.3 ± 0.6), U16 (ES = 3.0 ± 0.7) and LL players (ES = 2.0 ± 0.7). Middle forwards attained a likely superior pIFT (ES = 0.5 − 1.8) to all other positional groups.Conclusions: This study demonstrated that elite rugby league players possess superior PHIR capacities, whilst highlighting that pIFT can account for the disparities in body mass between groups.

Wearing lower-body compression garment with medium pressure impaired exercise-induced performance decrement during prolonged running.

ObjectiveTo investigate the effect of wearing a lower body compression garment (CG) exerting different pressure levels during prolonged running on exercise-induced muscle damage and the inflammatory response.MethodsEight male participants completed three exercise trials in a random order. The exercise consisted of 120 min of uphill running at 60% of VO2max. The exercise trials included 1) wearing a lower-body CG with 30 mmHg pressure [HIGH]; 2) wearing a lower-body CG with 15 mmHg pressure [MED]; and 3) wearing a lower-body garment with < 5 mmHg pressure [CON]. Heart rate (HR), and rate of perceived exertion for respiration and legs were monitored continuously during exercise. Time-course change in jump height was evaluated before and immediately after exercise. Blood samples were collected to determine blood glucose, lactate, serum creatine kinase, myoglobin, free fatty acids, glycerol, cortisol, and plasma interleukin-6 (IL-6) concentrations before exercise, 60 min of the 120 min exercise period, immediately after exercise, and 60 min after exercise.ResultsJump height was significantly higher immediately after the exercise in the MED trial compared with that in the HIGH trial (P = 0.04). Mean HR during the 120 min exercise was significantly lower in the MED trial (162 ± 4 bpm) than that in the CON trial (170 ± 4 bpm, P = 0.01). Plasma IL-6 concentrations increased significantly with exercise in all trials, but the area under the curve during exercise was significantly lower in the MED trial (397 ± 58 pg/ml·120 min) compared with that in the CON trial (670 ± 86 pg/ml·120 min, P = 0.04).ConclusionWearing a lower body CG exerting medium pressure (approximately 15 mmHg) significantly attenuated decrease in jump performance than that with wearing a lower body CG exerting high pressure (approximately 30 mmHg). Furthermore, exercise-induced increases in HR and the inflammatory response were significantly smaller with CG exerted 15mmHg than that with garment exerted < 5 mmHg.

Locomotion Mode Affects the Physiological Strain during Exercise at Walk-Run Transition Speed inElderly Men

This study investigated cardiorespiratory responses and rating of perceived exertion (RPE) during prolonged walking and running exercise performed at the walk-run transition speed (WRTS) in untrained healthy elderly men. 20 volunteers (mean±SE, age: 68.4±1.2 yrs; height: 170.0±0.02 cm; body mass: 74.7±2.3 kg) performed the following bouts of exercise: a) maximal cardiopulmonary exercise test (CPET); b) specific protocol to detect WRTS; and c) two 30-min walking and running bouts at WRTS. Expired gases were collected during exercise bouts via the Ultima CardiO2 metabolic analyzer. Compared to walking, running at the WRTS resulted in higher oxygen uptake (>0.27 L·min-1), pulmonary ventilation (>7.7 L·min-1), carbon dioxide output (>0.23 L·min-1), heart rate (>15 beats·min-1), oxygen pulse (>0.88 15 mL·beats-1), energy expenditure (>27 kcal) and cost of oxygen transport (>43 mL·kg-1·km-1·bout-1). The increase of overall and local RPEs with exercise duration was similar across locomotion modes (P<0.001). In all participants, %HRR and %VO2R throughout walking and running bouts were around or above the gas exchange threshold. In conclusion, elderly men exhibited higher cardiorespiratory responses during 30-min bouts of running than walking at WRTS. Nevertheless, walking corresponded to relative metabolic intensities compatible with preservation or improvement of cardiorespiratory fitness and should be preferable over running at WRTS in the untrained elderly characterized by poor fitness and reduced exercise tolerance.

Effects of a Submaximal 30-Minute Run on Peak Tibial Acceleration in Novice Runners

Peak positive tibial acceleration (PTA) immediately following foot strike during running is greater in runners with a history of tibial stress fracture. PTA does not increase over the course of a 20min run at lactate threshold pace (i.e., moderate effort) in highly trained runners. However, injury incidence in novice runners is higher, which may suggest that novice runners do not have the control strategy to prevent PTA from increasing over a prolonged run. PURPOSE: To assess the effects of a prolonged submaximal run on PTA in novice runners. METHODS: Male (n = 2) and female (n = 8) novice runners (24±5yrs; 1.69±0.12m; 70.7±15.6kg; 24.5±3.8kg/m2) who had been training for less than two years and ran on average at least 16km per week completed a 30min treadmill run at a self-selected speed equivalent to a rate of perceived exertion using the Borg scale between 10-13. A 3D accelerometer (480Hz, PCB Piezotronics, USA) used to measure PTA immediately following foot strike was attached to the distal anteromedial aspect of the right tibia along its longitudinal axis. Sagittal plane foot contact angle and ankle angle were also computed using 3D motion capture data (240Hz, Qualisys, Sweden). Data from five consecutive steps were collected after four (start), 15 (middle) and 30 min (end) of the prolonged run. A one-way repeated measures ANOVA was used assess a main effect of time on PTA (p ≤ 0.05). Post-hoc paired t-tests were used to compare mean differences among time points. Cohen’s d effect sizes were used to assess effect magnitudes. RESULTS: PTA was not different among time points (p = 0.87). PTA was unchanged between time points during the prolonged run (start: 3.58±1.43g; middle: 3.67±1.09g; end: 3.60±1.47g). Both foot contact angle and ankle angle at foot strike were unaffected by the run (p > 0.05). CONCLUSION: Our data suggest that PTA does not change over the course of submaximal prolonged run in novice runners. This finding is similar to unchanged PTA during a 20min moderately intense run in trained runners. These findings appear to indicate that, independent of running experience, PTA is unaffected by prolonged running. Changes in lower extremity motion and stiffness over prolonged runs of different lengths and intensities may alter active shock attenuation mechanisms and have different impacts on PTA on novice runners.

Il-6 Linkage To Exercise-induced Shifts In Lipid-related Metabolites

IL-6 and lipolysis have been linked in cell culture and IL-6 infusion studies, but this has not yet been tested using metabolomics-based procedures that allow the simultaneous evaluation of a high number of metabolites from the lipid super pathway following intensive exercise. PURPOSE: Metabolomic profiling and bioinformatic technologies were used to determine the relationship between exercise-induced increases in IL-6 and lipid-related metabolites. METHODS: Male runners (N=24, age 36.5±1.8 y) ran on treadmills to exhaustion (2.26±0.01 h, 24.9±1.3 km, 69.7±1.9% VO2max), with vastus lateralis muscle biopsy and blood samples collected before and after the running bout. RESULTS: The runners experienced a 33.7±4.2% decrease in muscle glycogen, 39.0±8.8-, 2.4±0.3-, and 1.4±0.1-fold increases in plasma IL-6, IL-8, and MCP-1, respectively, and 95.0±18.9% and 158±20.6% increases in cortisol and epinephrine, respectively (all, P < 0.001). The metabolomics analysis revealed changes in 209 plasma metabolites, especially long- and medium-chain fatty acids, fatty acid oxidation products (dicarboxylate and monohydroxy fatty acids, acylcarnitines), and ketone bodies. OPLS-DA modeling supported a strong separation in pre- and post-exercise samples (R2Y=0.964, Q2Y=0.902). OPLSR analysis failed to produce a viable model for the relationship between IL-6 and all lipid-related metabolites (R2Y = 0.76, Q2Y = - 0.0748), but did reveal a relationship between changes in serum cortisol and lipid-related metabolites (R2Y=1, Q2Y=0.434). Multiple structure equation models were evaluated based on IL-6, with the best fit pathway model showing a linkage of exercise time to IL-6, then carnitine, and 13-methylmyristic acid (a marker for adipose tissue lipolysis) and sebacate. CONCLUSION: This metabolomics-based analysis showed that the substantial increase in lipid metabolites after prolonged and intensive running was related more to changes in cortisol than increases in IL-6 and epinephrine, or muscle glycogen depletion. Taken together, the metabolomics-based data from this study do not support a strong relationship between the modest increase in IL-6 and the large increase in numerous lipid-related metabolites following prolonged and intensive running. Funding: Reoxcyn Discoveries Group, Salt Lake City, UT

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G-14 Thematic Poster - Biomechanics of Prolonged Running Saturday, June 3, 2017, 9: 00 AM - 11: 00 AM Room: 403: PDF Only

Differences in Pes Planus and Pes Cavus subtalar eversion/inversion before and after prolonged running, using a two-dimensional digital analysis.

In sports, there is a constant discussion about the hyper-pronation and supination of the foot during loading and its relation to injuries or discomfort. The purpose of the present study was to investigate the possible differences in the subtalar joint in the midstance phase of running, between individuals with Pes Planus and Pes Cavus, after 5 min and 45 min of running. Thirty-four subjects, meeting the requirements for Pes Planus (30 feet) and Pes Cavus (35 feet), according to the criteria for Medial Longitudinal Arch-angle, were included in the study. The calcaneal vertical angle, representing the eversion/inversion of the subtalar joint, was measured using with two-dimensional digital analysis and Dartfish Software with the subjects running barefoot on a treadmill, before and after 45 min of outside running wearing shoes. Both individuals with Pes Cavus and Pes Planus showed a significant increase in the calcaneal eversion (P<0.05) after 45 min of running. Between the groups, there was a significantly greater eversion of the Pes Planus, on the right foot, after 45 min of running (P<0.05) compared to the Pes Cavus. The effect of fatigue evident in the present study suggests that further biomechanical research should be considered when exposing the foot to the repetitive nature of running, conditions most likely responsible for the overrepresented overuse injuries among runners.

Acute effect of running exercise on physiological Achilles tendon blood flow.

Sonographically detectable intratendinous blood flow (IBF) is found in 50%-88% of Achilles tendinopathy patients as well as in up to 35% of asymptomatic Achilles tendons (AT). Although IBF is frequently associated with tendon pathology, it may also represent a physiological regulation, for example, due to increased blood flow in response to exercise. Therefore, this study aimed to investigate the acute effects of a standardized running exercise protocol on IBF assessed with Doppler ultrasound (DU) "Advanced dynamic flow" in healthy ATs. 10 recreationally active adults (5 f, 5m; 29±3years, 1.72±0.12m, 68±16kg, physical activity 206±145minute/wk) with no history of AT pain and inconspicious tendon structure performed 3 treadmill running tasks on separate days (M1-3) with DU examinations directly before and 5, 30, 60, and 120minutes after exercise. At M1, an incremental exercise test was used to determine the individual anaerobic threshold (IAT). At M2 and M3, participants performed 30-minute submaximal constant load tests (CL1 /CL2 ) with an intensity 5% below IAT. IBF in each tendon was quantified by counting the number of vessels. IBF increased in five ATs from no vessels at baseline to one to four vessels solely detectable 5minutes after CL1 or CL2 . One AT had persisting IBF (three vessels) throughout all examinations. Fourteen ATs revealed no IBF at all. Prolonged running led to a physiological, temporary appearance of IBF in 25% of asymptomatic ATs. To avoid exercise-induced IBF in clinical practice, DU examinations should be performed after 30minutes of rest.

LPS‐Induced TLR4 Activation During Prolonged Running and Cycling Events in Hot and Humid Environments

Lipopolysaccharide (LPS) is a gram‐negative bacterial marker that might be released into circulation during exercise‐heat stress. LPS induces an innate immune response by binding LPS‐binding protein (LBP) and its cognate receptor, TLR4 (toll‐like receptor 4), expressed on CD16+CD14+ circulating immune cells. LPS‐induced TLR4 activation results in robust immune responses which drive endotoxemia, sepsis, and putatively, exertional heatstroke pathophysiology.PURPOSEWe aimed to test the hypothesis that competing in prolonged cycling (50–100 mile event) or high‐intensity running (7 mile race) events in hot and humid environments (heat index&gt;80°F) result in LPS‐induced TLR4 activation and changes in cellular gene expression.METHODSWe recruited 64 subjects participating in the Hotter n' Hell Hundred (HHH) ultraendurance cycling event (Wichita Falls, TX) and 36 subjects racing in the Falmouth (FAL) Road Race (Falmouth, MA). We sampled venous blood pre (PRE) and immediately post (IP) each event, and also 30 minutes after IP (30IP) in FAL. We isolated circulating PBMCs (peripheral blood mononuclear cells) which were stained for surface markers CD14, CD16, and TLR4 using fluor‐conjugated antibodies. We used multi‐color digital flow cytometry on‐site to analyze cell populations. We also isolated anticoagulant‐treated plasma samples from whole blood for analysis of circulating LPS (Hycult Biotech, ELISA) and LBP (R&amp;D ELISA) concentrations. At both events, we measured environmental and physiological variables. We statistically analyzed data using repeated measures ANOVA (LSD post hoc, α‐level:p≤0.05) for differences (PRE vs. IP, PRE vs. 30IP).RESULTSCirculating LPS increased in both HHH riders and FAL racers by 25% (p&lt;0.05) and 39% (p&lt;0.04), respectively. By 30IP, FAL racers' circulating LPS levels had returned to PRE values (p&gt;0.19). In both races, circulating LBP remained unchanged (p&gt;0.33). CD14+CD16+ cells expressing TLR4 in circulation were significantly increased at IP (p&lt;0.05).CONCLUSIONWe conclude that circulating LPS is increased post‐exercise heat stress and analysis of downstream activation is required to determine role of LPS in exercise‐heat stress.Support or Funding InformationWe would like to thank Connecticut Institute for Clinical and Translational Science and McNair Scholars Program for funding the research and thank Hotter'N Hell Hundred and Falmouth Road Race for their support.

A Placebo-Controlled Trial of Riboflavin for Enhancement of Ultramarathon Recovery

BackgroundRiboflavin is known to protect tissue from oxidative damage but, to our knowledge, has not been explored as a means to control exercise-related muscle soreness. This study investigated whether acute ingestion of riboflavin reduces muscle pain and soreness during and after completion of a 161-km ultramarathon and improves functional recovery after the event.MethodsIn this double-blind, placebo-controlled trial, participants of the 2016 161-km Western States Endurance Run were assigned to receive a riboflavin or placebo capsule shortly before the race start and when reaching 90 km. Capsules contained either 100 mg of riboflavin or 95 mg of maltodextrin and 5 mg of 10% ß-carotene. Subjects provided muscle pain and soreness ratings before, during, and immediately after the race and for the 10 subsequent days. Subjects also completed 400-m runs at maximum speed on days 3, 5, and 10 after the race.ResultsFor the 32 (18 in the riboflavin group, 14 in the placebo group) race finishers completing the study, muscle pain and soreness ratings during and immediately after the race were found to be significantly lower (p = .043) for the riboflavin group. Analysis of the 400-m run times also showed significantly faster (p < .05) times for the riboflavin group than the placebo group at post-race days 3 and 5. Both groups showed that muscle pain and soreness had returned to pre-race levels by 5 days after the race and that 400-m run times had returned to pre-race performance levels by 10 days after the race.ConclusionsThis preliminary work suggests that riboflavin supplementation before and during prolonged running might reduce muscle pain and soreness during and at the completion of the exercise and may enhance early functional recovery after the exercise.

Extended Duration Running and Impulse Loading Characteristics of an Acoustic Bearing with Enhanced Geometry

This paper presents performance during prolonged running of the acoustic bearing when PZTs are switched off and when they are switched on. The effect of active PZT on shaft’s displacements in X and Y directions is clearly demonstrated. Performance of the acoustic bearing was also assessed when an impulse force was applied to the running shaft at speed. Once again the benefits of having PZTs active are beyond doubt. The instability caused by the impulse force was rapidly mitigated as the bearing returned to its usual dynamics within around two second. In contrast, dynamics of the acoustic bearing operating with PZTs switched off was significantly disturbed and in the time of the test never returned to its status before application of the impulse force.

Heavy strength training improves running and cycling performance following prolonged submaximal work in well-trained female athletes.

The purpose of this study was to investigate the effects of adding heavy strength training to female duathletes' normal endurance training on both cycling and running performance. Nineteen well‐trained female duathletes (VO2max cycling: 54 ± 3 ml∙kg−1∙min−1, VO2max running: 53 ± 3 ml∙kg−1∙min−1) were randomly assigned to either normal endurance training (E, n = 8) or normal endurance training combined with strength training (E+S, n = 11). The strength training consisted of four lower body exercises [3 × 4‐10 repetition maximum (RM)] twice a week for 11 weeks. Running and cycling performance were assessed using 5‐min all‐out tests, performed immediately after prolonged periods of submaximal work (3 h cycling or 1.5 h running). E+S increased 1RM in half squat (45 ± 22%) and lean mass in the legs (3.1 ± 4.0%) more than E. Performance during the 5‐min all‐out test increased in both cycling (7.0 ± 4.5%) and running (4.7 ± 6.0%) in E+S, whereas no changes occurred in E. The changes in running performance were different between groups. E+S reduced oxygen consumption and heart rate during the final 2 h of prolonged cycling, whereas no changes occurred in E. No changes occurred during the prolonged running in any group. Adding strength training to normal endurance training in well‐trained female duathletes improved both running and cycling performance when tested immediately after prolonged submaximal work.