Prolonged Running Research Articles

Achilles Tendon Mechanical Properties After Both Prolonged Continuous Running and Prolonged Intermittent Shuttle Running in Cricket Batting

Effects of prolonged running on Achilles tendon properties were assessed after a 60 min treadmill run and 140 min intermittent shuttle running (simulated cricket batting innings). Before and after exercise, 11 participants performed ramp-up plantar flexions to maximum-voluntary-contraction before gradual relaxation. Muscle-tendon-junction displacement was measured with ultrasonography. Tendon force was estimated using dynamometry and a musculoskeletal model. Gradients of the ramp-up force-displacement curves fitted between 0-40% and 50-90% of the preexercise maximal force determined stiffness in the low- and high-force-range, respectively. Hysteresis was determined using the ramp-up and relaxation force-displacement curves and elastic energy storage from the area under the ramp-up curve. In simulated batting, correlations between tendon properties and shuttle times were also assessed. After both protocols, Achilles tendon force decreased (4% to 5%, P < .050), but there were no changes in stiffness, hysteresis, or elastic energy. In simulated batting, Achilles tendon force and stiffness were both correlated to mean turn and mean sprint times (r = -0.719 to -0.830, P < .050). Neither protocol resulted in fatigue-related changes in tendon properties, but higher tendon stiffness and plantar flexion force were related to faster turn and sprint times, possibly by improving force transmission and control of movement when decelerating and accelerating.

Pre-Exercise Hyperhydration-Induced Bodyweight Gain Does Not Alter Prolonged Treadmill Running Time-Trial Performance in Warm Ambient Conditions

This study compared the effect of pre-exercise hyperhydration (PEH) and pre-exercise euhydration (PEE) upon treadmill running time-trial (TT) performance in the heat. Six highly trained runners or triathletes underwent two 18 km TT runs (~28 °C, 25%–30% RH) on a motorized treadmill, in a randomized, crossover fashion, while being euhydrated or after hyperhydration with 26 mL/kg bodyweight (BW) of a 130 mmol/L sodium solution. Subjects then ran four successive 4.5 km blocks alternating between 2.5 km at 1% and 2 km at 6% gradient, while drinking a total of 7 mL/kg BW of a 6% sports drink solution (Gatorade, USA). PEH increased BW by 1.00 ± 0.34 kg (P < 0.01) and, compared with PEE, reduced BW loss from 3.1% ± 0.3% (EUH) to 1.4% ± 0.4% (HYP) (P < 0.01) during exercise. Running TT time did not differ between groups (PEH: 85.6 ± 11.6 min; PEE: 85.3 ± 9.6 min, P = 0.82). Heart rate (5 ± 1 beats/min) and rectal (0.3 ± 0.1 °C) and body (0.2 ± 0.1 °C) temperatures of PEE were higher than those of PEH (P < 0.05). There was no significant difference in abdominal discomfort and perceived exertion or heat stress between groups. Our results suggest that pre-exercise sodium-induced hyperhydration of a magnitude of 1 L does not alter 80–90 min running TT performance under warm conditions in highly-trained runners drinking ~500 mL sports drink during exercise.

Impact reduction during running: efficiency of simple acute interventions in recreational runners

Running-related stress fractures have been associated with the overall impact intensity, which has recently been described through the loading rate (LR). Our purpose was to evaluate the effects of four acute interventions with specific focus on LR: wearing racing shoes (RACE), increasing step frequency by 10 % (FREQ), adopting a midfoot strike pattern (MIDFOOT) and combining these three interventions (COMBI). Nine rearfoot-strike subjects performed five 5-min trials during which running kinetics, kinematics and spring-mass behavior were measured for ten consecutive steps on an instrumented treadmill. Electromyographic activity of gastrocnemius lateralis, tibialis anterior, biceps femoris and vastus lateralis muscles was quantified over different phases of the stride cycle. LR was significantly and similarly reduced in MIDFOOT (37.4 ± 7.20 BW s(-1), -56.9 ± 50.0 %) and COMBI (36.8 ± 7.15 BW s(-1), -55.6 ± 29.2 %) conditions compared to NORM (56.3 ± 11.5 BW s(-1), both P < 0.001). RACE (51.1 ± 9.81 BW s(-1)) and FREQ (52.7 ± 11.0 BW s(-1)) conditions had no significant effects on LR. Running with a midfoot strike pattern resulted in a significant increase in gastrocnemius lateralis pre-activation (208 ± 97.4 %, P < 0.05) and in a significant decrease in tibialis anterior EMG activity (56.2 ± 15.5 %, P < 0.05) averaged over the entire stride cycle. The acute attenuation of foot-ground impact seems to be mostly related to the use of a midfoot strike pattern and to a higher pre-activation of the gastrocnemius lateralis. Further studies are needed to test these results in prolonged running exercises and in the long term.

Identifying risk factors for contact injury in professional rugby league players – Application of a frailty model for recurrent injury

ObjectivesWell-developed physical qualities may protect against contact injuries. However, the potential contribution of physical qualities as risk or protective factors to contact injury risk is yet to be determined for rugby league. This study applied a frailty survival model that accounts for recurrent injury to identify risk factors for all physiotherapist-reported contact injury in professional rugby league players. DesignProspective cohort study. MethodsSixty-six professional rugby league players participated in this three successive year prospective study. At the start of each season, all players underwent measurements of standard anthropometry (height, body mass, and sum of seven skinfolds), speed (10m and 40m sprint), muscular strength (1 repetition maximum [RM] bench press, 1RM squat, 1RM weighted chin-ups), power (vertical jump, bench throw, 1RM power clean, jump squat), and endurance (maximum repetition bench press with 60kg resistance), repeated-sprint ability (12×20m sprints performed on a 20s cycle), prolonged high-intensity intermittent running ability (8×12s maximal effort shuttles performed on a 48s cycle), and maximal aerobic power (multi-stage fitness test). Data was used to demonstrate the application of the frailty model extension of the Cox proportional regression model for recurrent events to identify factors associated with a high hazard ratio (HR) of injury. ResultsHeavier (body mass, HR=2.6, 95% CI=1.2–5.7), and faster (40m sprint, HR=2.1, 95% CI=1.0–4.2) players, and those with poorly developed prolonged high-intensity intermittent running ability (HR=2.9, 95% CI=1.7–5.0) and upper-body strength (chin-up, HR=2.2, 95% CI=1.3–3.7) had a higher incidence of contact injuries. ConclusionsThis study demonstrates application of a novel statistical approach for the analysis of injury data that is recurrent in nature. This approach identified that the greater impact forces generated from heavier players with faster speed may result in an increase in recurrent contact injury rates. However, the development of prolonged high-intensity intermittent running ability and upper-body strength and power may assist to reduce the risk of contact injury in professional rugby league players.

Hemolysis induced by an extreme mountain ultra‐marathon is not associated with a decrease in total red blood cell volume

Prolonged running is known to induce hemolysis. It has been suggested that hemolysis may lead to a significant loss of red blood cells; however, its actual impact on the erythrocyte pool is unknown. Here, we test the hypothesis that prolonged running with high hemolytic potential decreases total red blood cell volume (RCV). Hemolysis (n = 22) and RCV (n = 19) were quantified in ultra-marathon runners before and after a 166-km long mountain ultra-endurance marathon (RUN) with 9500 m of altitude gain/loss. Assessment of total hemoglobin mass (Hbmass) and RCV was performed using a carbon monoxide rebreathing technique. RUN induced a marked acute-phase response and promoted hemolysis, as shown by a decrease in serum haptoglobin (P < 0.05). Elevated serum erythropoietin concentration and reticulocyte count after RUN were indicative of erythropoietic stimulation. Following RUN, runners experienced hemodilution, mediated by a large plasma volume expansion and associated with a large increase in plasma aldosterone. However, neither Hbmass nor RCV were found to be altered after RUN. Our findings indicate that mechanical/physiological stress associated with RUN promotes hemolysis but this has no impact on total erythrocyte volume. We therefore suggest that exercise 'anemia' is entirely due to plasma volume expansion and not to a concomitant decrease in RCV.

Sacrificing economy to improve running performance—a reality in the ultramarathon?

ultramarathons have become increasingly popular in recent years. Although complex tactical and psychological-motivational factors play important roles in performance ([Fig. 1][1]), running velocity sustained over a prolonged time is directly proportional to maximal sustainable Vo2 and inversely

HBOC Attenuates Intense Exercise-Induced Cardiac Dysfunction

The purpose of this study was to investigate whether hemoglobin-based oxygen carrier (HBOC) could protect the heart from intense exercise-induced myocardial dysfunction. Adult male Sprague-Dawley rats were subjected to 5-h intense prolonged running on treadmill with or without HBOC pre-treatment. Immediately after exercise, the heart rate (HR) and oxygen delivery capacity of the blood were measured. After 1 h of rest, echocardiography was performed to assess the post-exercise cardiac function. Then all the hearts were isolated and perfused using the Langendorff model for 1 h. Our results proved that pronged exercise caused significant LV dysfunction, while HBOC pre-treatment attenuated such a damage, as evidenced by the increased oxygen delivery, cardiac fractional shortening (FS), rate-pressure product (RPP), ± dp/dt and coronary flow rate (CF) and decreased myocardial necrosis. The releases of cardiac enzymes, including creatine kinase-MB (CK-MB) and cardiac troponin-I (cTnI) were markedly reduced. No significant difference of cardiac infarct size was observed among groups. In addition, HBOC significantly elevated superoxide dismutase (SOD) activity and decreased hydrogen peroxide (H2O2) formation, which indicated the exercise-induced cardiac oxidative damage was inhibited. In conclusion, HBOC pre-treatment showed a promising cardioprotective effect on prolonged exercise-induced cardiac dysfunction, which was probably associated with its ability to decrease myocardium oxidative stress.

Consequences Of Rising Humidity Level On Circulatory Responses During Prolonged Intense Exercise

The combined metabolic and thermoregulatory demands experienced during exercise in the heat impose an exceptional stress on the circulatory system. To date, much of what is known about circulatory stress during exercise in the heat has focused on primarily dry environment (~ 40% rh) with limited studies carried in higher humidity (> 60% rh) conditions. This study was designed to investigate the influence of humid condition on circulatory responses during prolonged intense running exercise among elite runners. On separate days, 11 male elite runners ran for 60 minutes at an intensity of 70% VO2 max across three different humidity levels of HH (71% rh), NH (43% rh) and LH (26.2% rh) with the ambient temperature set at 300C. Thermal stress was found to increase during exercise in the HH condition as both Tre and Tsk steadily rise across time. Circulatory stress markedly increased during exercise in higher humidity levels. Heart rate was significantly higher in the HH condition with its level increasing to 92% of HRmax. The upwards drift in HR was significantly higher in HH within the last ten minutes of exercise. Contrary, stroke volume recorded a steady decline during exercise with a significantly lower SV in the HH as compared with the NH and LH. Results implicate rising humidity level will impose greater circulatory stress during prolonged intense exercise. The consequence from this circulatory stress will result in limited ability for an athlete to sustain his exercise capacity when HR reaches maximal level.

WLCG Operations and the First Prolonged LHC Run

By the time of CHEP 2010 we had accumulated just over 6 months' experience with proton-proton data taking, production and analysis at the LHC. This paper addresses the issues seen from the point of view of the WLCG Service. In particular, it answers the following questions: Did the WLCG service delivered quantitatively and qualitatively? Were the "key performance indicators" a reliable and accurate measure of the service quality? Were the inevitable service issues been resolved in a sufficiently rapid fashion? What are the key areas of improvement required not only for long-term sustainable operations, but also to embrace new technologies. It concludes with a summary of our readiness for data taking in the light of real experience.

Relationships between physiological, anthropometric, and skill qualities and playing performance in professional rugby league players

In this study, we investigated the relationship between physiological, anthropometric, and skill qualities and playing performance in professional rugby league players. Fifty-eight high-performance rugby league players underwent measurements for anthropometry (height, body mass, sum of seven skinfolds), physiological (speed, change of direction speed, lower body muscular power, repeated-sprint ability, prolonged high-intensity intermittent running ability, and estimated maximal aerobic power), technical skill (tackling proficiency, draw and pass proficiency), and perceptual skill (reactive agility, pattern recall, pattern prediction) qualities. National Rugby League matches were coded for attacking (e.g. line breaks, try assists, etc.) and defensive (e.g. missed tackles, tackling efficiency, etc.) statistics commonly used to assess rugby league playing performance. The number of line break assists was significantly associated (P < 0.05) with greater playing experience (r = 0.36), dual-task draw and pass proficiency (r = 0.54), reactive agility (r = 0.29), and pattern recall (r = 0.32) and prediction (r = 0.28) ability, while faster speed over 40 m (r = −0.42) was associated (P < 0.05) with a higher number of tries scored. Greater age and playing experience, better lower body muscular power, and faster 10 m and 40 m speed were significantly associated (P < 0.05) with the number of tackle attempts (positive), tackles completed (positive), and proportion of missed tackles (negative). These findings demonstrate that well-developed physical and skill qualities are associated with effective playing performance in National Rugby League players.

Ice Slurry Ingestion Increases Running Time in the Heat

To examine the effect of drinking an ice slurry (slushy) compared with cold water on prolonged submaximal exercise performed in the heat and on thermoregulatory responses. Crossover trial, with the 2 conditions counterbalanced and in random order. Results were adjusted for multiple comparisons by the method of Bonferroni. Exercise laboratory study; Edith Cowan University, Western Australia. Moderately active male volunteers (n = 10; mean age, 28 years) who participated in recreational sport and who had no injuries or history of heat illness were included. Five to 14 days before the trials, the participants were familiarized with the procedure by a progressive treadmill run to volitional exhaustion at their previously determined first ventilatory threshold running speed, in the same hot environment as the trials (34°C, 55% relative humidity). The 2 experimental trials were completed at the same time of day, 5 to 20 days apart. During the first 15 minutes, the participants rested while baseline measurements were taken. Over the next 30 minutes, they drank either a 7.5 g/kg flavored ice slurry (-1°C) or the same volume of flavored cold water (4°C) and then commenced the treadmill run. Participants were instructed to keep their normal lifestyle habits stable. In the 24 hours preceding the trials, they were asked to avoid strenuous exercise and to consume a specified amount of carbohydrate and fluid but no alcohol, caffeine, nonsteroidal anti-inflammatory drugs, or nutritional supplements. Urine and blood samples were taken, and respiratory variables, heart rate, and rectal and skin temperatures were continuously monitored. Heat storage was calculated from temperature and anthropomorphic measurements. The primary outcome measures were comparisons of run time to exhaustion, perceived exhaustion, heat storage capacity, and changes in rectal and skin body temperatures during the 2 trials. All 10 participants took longer to fatigue (range, 2.4-14.2 minutes) after ice slurry (mean, 50.2 minutes; SD, 8.5 minutes) than after cold water (mean, 40.7 minutes; SD, 7.2 minutes) ingestion (relative mean increase, 19%; SD, 6%; P = 0.001). Mean rectal temperature during the rest period did not differ between conditions but was 0.32°C lower after drinking the ice slurry than after cold water ingestion before the start of exercise (P = 0.001). During the treadmill runs, rectal temperature rose for both conditions but remained lower for the ice slurry condition for the first 30 minutes of exercise (P = 0.001). After exercise to exhaustion, mean rectal temperature was higher for the ice slurry condition than for the cold water condition (39.36°; SD, 0.41° vs 39.05°; SD, 0.37°; P = 0.001). Mean skin temperature showed a similar pattern to rectal temperature except that the conditions did not differ during or after exercise. During the prerun period, heat storage was lower after ice slurry than after cold water ingestion (-18.28 W/m vs -7.84 W/m; P = 0.001), but during exercise, heat storage was greater after ice slurry than after cold water ingestion (100.10 W/m vs 78.93 W/m; P = 0.005), although the mean rates of heat storage were similar between conditions. During exercise, participant ratings of thermal sensation and perceived exertion were lower after ice slurry than after cold water ingestion, except at exhaustion, when the ratings were similar. Ice slurry (slushy) compared with cold water ingestion prolonged running time to exhaustion in hot and humid conditions, reduced rectal temperature during exercise, and allowed rectal temperature to rise higher before the runner reached exhaustion.

Red Ginseng Supplementation More Effectively Alleviates Psychological than Physical Fatigue

Red ginseng (RG, the extract of Panax ginseng Meyer) has various biological and psychological activities and may also alleviate fatigue-related disorders. The present study was undertaken to evaluate what kind of fatigue red ginseng alleviate. Animals were orally administered with 50, 100, 200, 400 mg/kg of RG for 7 days. Before experiments were performed. Physiological stress (swimming, rotarod, and wire test) are behavioral parameters used to represent physical fatigue. Restraint stress and electric field test to a certain degree, induce psychological fatigue in animals. Plasma concentration of lactate and corticosterone (CORT) were also measured after these behavioral assays. RG supplementation (100 mg/kg) increased movement duration and rearing frequency of restrainted mice in comparison with control. 100 and 200 mg/kg of RG increased swimming time in cold water (8±4℃) while at 100 mg/kg, RG increased electric field crossing over frequencies. 50, 100 and 200 mg/kg RG prolonged running time on the rotarod and at 100 mg/kg, it increased balancing time on the wire. RG at those doses also reduced falling frequencies. RG supplementation decreased plasma CORT levels, which was increased by stress. Lactate levels were not significantly altered. These results suggest that RG supplementation can alleviate more the damages induced by psychological than physical fatigue.

The effects of carbohydrate ingestion during endurance running on post-exercise inflammation and hepcidin levels

The effect of carbohydrate (CHO) consumption during prolonged endurance running on post-exercise inflammation and hepcidin levels was investigated. Eleven well-trained male endurance athletes completed a graded exercise test, followed by two experimental running trials in a randomized order. The two experimental trials consisted of a 90 min run at 75% of the peak oxygen uptake velocity (vVO(2peak)), while consuming a solution with either 6% CHO or a placebo (PLA) equivalent at 3 ml kg(-1) every 20 min. Serum interleukin-6 (IL-6), free hemoglobin (Hb), haptoglobin (Hp), hepcidin and iron parameters were assessed throughout the post-run recovery period. Serum iron and IL-6 were significantly elevated immediately post-run in both CHO and PLA (p ≤ 0.05), with no differences between trials. Serum-free Hb increased and Hp decreased significantly immediately post-run in both conditions (p ≤ 0.05). Serum soluble transferrin receptor levels were significantly below the baseline at 3 and 24 h post-run in both conditions (p ≤ 0.05). Serum hepcidin concentration recorded 3 h post-run in both conditions was significantly elevated (p ≤ 0.05), and had returned to the baseline by 24 h post-run (p ≤ 0.05). The use of a 6% CHO solution at 3 ml kg(-1) 20 min(-1) during endurance running did not attenuate the inflammatory response and subsequent increase in serum hepcidin levels during the post-run recovery period.

Relative importance of physiological, anthropometric, and skill qualities to team selection in professional rugby league

This study investigated the relative importance of physiological, anthropometric, and skill qualities to team selection in professional rugby league. Eighty-six high performance rugby league players underwent measurements of anthropometric (height, body mass, sum of seven skinfolds), physiological (speed, change of direction speed, lower body muscular power, repeated-sprint ability, prolonged high-intensity intermittent running ability, and maximal aerobic power), technical skill (tackling proficiency, draw and pass proficiency), and perceptual skill (reactive agility, pattern recall, pattern prediction) qualities. A linear discriminant analysis was also conducted comparing those players successful in gaining selection into the professional National Rugby League team with those not selected to determine which, if any, of these qualities could predict selection. Players selected to play in the first National Rugby League game of the season were older, more experienced, leaner, had faster 10m and 40m sprint times, and superior vertical jump performances, maximal aerobic power, tackling proficiency and dual-task draw and pass ability than non-selected players. Skinfold thickness and dual-task draw and pass proficiency were the only variables that contributed significantly (P < 0.05) to the discriminant analysis of selected and non-selected players. These findings suggest that selected physiological, anthropometric, and skill qualities may influence team selection in professional rugby league.

Intravascular haemolysis during prolonged running on asphalt and natural grass in long and middle distance runners

Surface features such as uneven playing surfaces, low impact absorption capacity and inappropriate friction/traction characteristics are connected with injury prevalence whereas force impact during foot strike has been suggested to be an important mechanism of intravascular haemolysis during running. We aimed to evaluate intravascular haemolysis during running and compare the effect of running on two different types of surfaces on haemolysis. We selected two surfaces (asphalt and grass) on which these athletes usually run. Participants were randomly assigned to group A (asphalt) or group B (grass) with 10 athletes in each group. Each athlete completed one hour of running at the calculated target heart rate (60–70%). Venous blood samples were collected before and immediately after running. We measured unconjugated bilirubin (UBR) (mg · dl−1), lactate dehydrogenase (LDH) (μ · ml−1), haemoglobin (g · l−1) and serum ferritin (ng · ml−1) as indicators of haemolysis. Athletes who ran on grass demonstrated an increase in the haematological parameters (UBR: P < 0.01, LDH: P < 0.05) when compared to athletes who ran on asphalt (UBR: P < 0.05, LDH: P = 0.241). Our findings indicate that intravascular haemolysis occurs significantly after prolonged running. Furthermore, we conclude that uneven grass surface results in greater haemolysis compared to asphalt road.

Beverage carbohydrate concentration influences the intermittent endurance capacity of adolescent team games players during prolonged intermittent running

This study investigated the influence of consuming a 2, 6, and 10% carbohydrate-electrolyte (CHO-E) solution on the intermittent endurance capacity and sprint performance of adolescent team games players. Seven participants (five males and two females; mean age 13.3 ± 0.5 years, height 1.71 ± 0.05 m, body mass (BM) 62.0 ± 6.3 kg) performed three trials separated by 3-7 days. In each trial, they completed four 15-min periods of part A of the Loughborough Intermittent Shuttle Test (LIST) followed by an intermittent run to exhaustion (part B). Participants consumed 5 ml kg(-1) BM of the solution during the 5-min pre-exercise period, and a further 2 ml kg(-1) BM every 15 min during part A of the LIST. Intermittent endurance capacity increased by 34% with ingestion of the 6% CHO-E solution compared with the 10% solution (5.5 ± 0.8 vs. 4.1 ± 1.5 min, P < 0.05), equating to a distance of 931 ± 172 versus 706 ± 272 m (P < 0.05). There was no significant difference between the 2% (4.8 ± 1.2 min) and 6% (P = 0.10) or the 2 and 10% solutions (P = 0.09). Carbohydrate concentration did not significantly influence mean 15-m sprint time (P = 0.38). These results suggest that the carbohydrate concentration of an ingested solution influences the intermittent endurance capacity of adolescent team games players with a 6% solution significantly more effective than a 10% solution.

Regeneration of CuZnO&lt;sub&gt;x&lt;/sub&gt;/γ-Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; as a Heterogeneous Catalyst in CWPO Process

This paper evaluates the catalytic effectiveness of CuZnOx/γ-Al2O3 catalyst for the degradation of an azo dye, acid red GR, using H2O2 as an oxidant, under very mild conditions (atmospheric pressure and t = 40 ). In the catalytic wet peroxide oxidation (CWPO) process, the results show that it is possible to remove 80% of COD during the initial 30 h. But a considerable drop of catalytic activity is found after prolonged run. As characterization datas shown, the deactivation of the catalyst is caused by the depositon of intermediates on the surface and serious coverage of the active sites. However, calcination method which is possible to burn the organic species that trapped in the catalyst reaches complete restoration of the spent catalyst.

Arterial Compliance Decreases Following Ultra-Endurance Competition

It is well established that habitual aerobic exercise training is associated with an increase in arterial compliance. A small number of studies have examined the effects of an acute bout of aerobic exercise on measures of arterial compliance, with the conclusion that short duration exercise leads to an increased compliance. However, the response to prolonged ultra-endurance exercise is currently unclear. PURPOSE: To assess the change in arterial compliance following prolonged endurance exercise in healthy athletes with normal baseline measures. METHODS: Arterial compliance was measured non-invasively using applanation tonometery (CR-3000, HDI) at least 1 day prior to competition and approximately 30 min after completion of an ultra-endurance (120 km or 195 km) mountain trail running race. Radial arterial waveforms were collected from the right arm in conjunction with automated blood pressure on the left arm, allowing estimation of both large (capacitive arterial compliance) and small (oscillatory or reflective) artery compliance. Measures of pre- and post-race weight, seated blood pressure (BP) and heart rate were also recorded. Comparisons were made using paired t-tests and ANOVA to examine whether race distance or gender affected outcomes. Associations between race time (pace) and pre-post changes were examined using Pearson correlation. RESULTS: Race completion took approximately 25.8 ± 3.5 hr and 37.4 ±4.3 hr to complete the 120 and 195 km courses respectively with no significant difference in average pace between distances. Mean systolic and diastolic BP were maintained pre- to post-race, despite a significant decrease (4.6 ± 15.9 kg) in weight, likely reflecting fluid loss. A moderate relationship (r = 0.49, p = 0.027) existed between decreases in systolic BP and increasing age. There was no significant change in small artery compliance; however, large artery compliance decreased from 16.1 ± 4.4 to 13.6 ± 3.8 mL/mmHg × 10. CONCLUSION: Participation in prolonged ultra-endurance running led to acute decreases in arterial compliance. Further research is required to determine the effects of these changes on cardiovascular function and health.

Antimicrobial Protein Response to Prolonged Running

Antimicrobial Protein Response to Prolonged Running

Classification of muscle activity based on effort level during constant pace running

During running, psychologic and physiologic changes are manifested in the perception of effort, muscle properties and movement strategies. The latter two aspects are expressed as changes in electromyographic (EMG) activity. This paper tests the hypothesis that the EMG signals change in a systematic way during a run and that these changes are related to the effort level of the runner. Fifteen female recreational runners performed 1-h treadmill runs at a constant speed (95% of speed at ventilatory threshold). EMG signals were recorded from four muscles (tibialis anterior, gastrocnemius medialis, vastus lateralis, and semitendinosus). The wavelet transformed EMG data were used to discriminate between different effort phases of running using a support vector machine (SVM) approach. The effect of the penalty parameter, C, and cross validation folds, n, used were evaluated and found to have little influence on the outcome. Recognition rates of >80% were achieved for all C and n values across all muscles. Average recognition rates were: TA – 89.2, GM – 88.3%, VL – 84.6% and ST – 94.0%. These results suggest that selected lower extremity EMG signals using wavelet-based methods contained highly systematic differences that could be used by the SVM to discriminate between the low- and high-effort stages of prolonged running.