Male Distance Runners Research Articles

The relationship between core stability and some performance parameters between fourteen and sixteen year old group male long distance runners and football players

The relationship between core stability and some performance parameters between fourteen and sixteen year old group male long distance runners and football players

Effect of low energy availability during three consecutive days of endurance training on iron metabolism in male long distance runners.

We investigated the effect of low energy availability (LEA) during three consecutive days of endurance training on muscle glycogen content and iron metabolism. Six male long distance runners completed three consecutive days of endurance training under LEA or neutral energy availability (NEA) conditions. Energy availability was set at 20 kcal/kg fat‐free mass (FFM)/day for LEA and 45 kcal/kg FFM/day for NEA. The subjects ran for 75 min at 70% of maximal oxygen uptake ( V˙O2max) on days 1–3. Venous blood samples were collected following an overnight fast on days 1–4, immediately and 3 hr after exercise on day 3. The muscle glycogen content on days 1–4 was evaluated by carbon‐magnetic resonance spectroscopy. In LEA condition, the body weight and muscle glycogen content on days 2–4, and the FFM on days 2 and 4 were significantly lower than those on day1 (p < .05 vs. day1), whereas no significant change was observed throughout the training period in NEA condition. On day 3, muscle glycogen content before exercise was negatively correlated with serum iron level (immediately after exercise, 3 hr after exercise), serum hepcidin level immediately after exercise, and plasma IL‐6 level immediately after exercise (p < .05). Moreover, serum hepcidin level on day 4 was significantly higher in LEA condition than that in NEA condition (p < .05). In conclusion, three consecutive days of endurance training under LEA reduced the muscle glycogen content with concomitant increased serum hepcidin levels in male long distance runners.

Plasma Hepcidin Increases with Prolonged Running in Male, but Not Female, Collegiate Distance Runners with Low Iron Stores

Abstract Objectives Hepcidin is a negative regulator of extracellular iron availability and dietary iron absorption. Previous studies have shown that hepcidin increases with prolonged endurance exercise, but not in those with low iron stores (serum ferritin &amp;lt;30 ng/mL). The objective of this study was to determine the plasma hepcidin response to exercise, compared to rest, in highly trained male and female collegiate distance runners. Methods In a cross-over design, healthy male (n = 14; age 20.2 ± 1.4 y; BMI 20.4 ± 1.6 kg/m2; VO2 max 69.8 ± 5.6 mL/kg/min) and female (n = 14; age 20.1 ± 1.4 y, P = 0.79; BMI 18.1 ± 1.6 kg/m2, P &amp;lt; 0.001; VO2 max 62.5 ± 4.2 mL/kg/min, P &amp;lt; 0.001) collegiate distance runners performed a bout of running (males: 109.8 ± 8.7 min, 15.0 ± 1.3 miles; females: 87.7 ± 10.4 min, P &amp;lt; 0.0001, 11.3 ± 1.5 miles, P &amp;lt; 0.0001) or no activity (rest) separated by 2 weeks. Indicators of iron status and plasma hepcidin were determined at baseline and three hours after exercise or rest. Dietary iron and total iron intake (dietary iron + iron from supplements) were determined by Food Frequency Questionnaires. Results Serum ferritin (males: 24.0 ± 15.9 ng/mL, females: 19.4 ± 9.5 ng/mL, P = 0.39) and plasma hepcidin (males: 22.3 ± 20.6 ng/mL, females: 24.6 ± 19.6 ng/mL, P = 0.77) did not differ between males and females at baseline. Baseline hemoglobin (males: 14.5 ± 0.8 g/dL, females: 13.4 ± 1.0 g/dL, P &amp;lt; 0.01) and hematocrit (males: 45.3 ± 2.2%, females: 42.1 ± 2.6%, P &amp;lt; 0.01) were greater in males compared to females. Dietary iron intake (males: 18.6 ± 6.3 mg/d, females: 17.1 ± 6.4 mg/d, P = 0.55) and total iron intake (males: 48.7 ± 32.9 mg/d, females: 64.6 ± 32.3 mg/d, P = 0.22) did not differ between males and females. Plasma hepcidin increased with exercise compared to rest in males (change from rest: 30.3 ± 42.0 ng/mL, P = 0.02) but not in females (change from rest: 0.8 ± 32.0 ng/mL, P = 0.93). Change in plasma hepcidin with exercise was correlated with sex (R = 0.380, P = 0.05) and BMI (R = 0.383, P = 0.04), but not baseline ferritin, run time, run distance, hemoglobin, hematocrit, dietary iron, or total iron intake (P &amp;gt; 0.05 for all). Conclusions The post-exercise hepcidin response occurs in male, but not female, collegiate distance runners with low iron stores. These findings indicate that declines in iron status in female distance runners are independent of exercise-induced hepcidin. Funding Sources Intramural funds to S.R.H.

Short-term ubiquinol-10 supplementation alleviates tissue damage in muscle and fatigue caused by strenuous exercise in male distance runners.

Background: Coenzyme Q10 (CoQ10) is the electron transporter in oxidative phosphorylation and an endogenous antioxidant. Recent researches have indicated that doses of 200-300mg/day are needed to recognize effects to prevent oxidative damage in athletes, and the reduced form of CoQ10, ubiquinol-10, is more bioavailable than its oxidized form. Therefore, we hypothesized that higher doses of ubiquinol-10 could elevate plasma CoQ10 levels rapidly and exert physiological benefits in athletes. Therefore, a placebo controlled, double blinded test was carried out to determine the effects of ubiquinol-10 on the extravasate enzymes and fatigue levels of distance runners. Methods: Sixteen male collegiate distance runners were allocated to two groups receiving 300mg/day of ubiquinol-10 (19.8±1.7 years) or a placebo (20.1±1.6years) for 12 days during summer training that comprised 25- and 40-km runs on days 7 and 9, respectively. Results: Ubiquinol-10 elevated plasma CoQ10 concentration to 5.62μg/mL and significantly decreased activities of the serum extravasate enzymes, CK, ALT, LDH (P<0.01), and AST (P<0.05) on day 6. Subjective fatigue status was significantly elevated on day 10 (the day after the 45-km run) in the placebo group (P<0.001), but did not significantly change in the group given ubiquinol-10. Therefore, ubiquinol-10 could mitigate tissue damage and alleviate fatigue status in distance runners during summer training. Conclusions: Ubiquinol-10 (300mg/day) supplementation elevated plasma CoQ10 concentrations almost to plateau levels, decreased extravasate enzymes within six days, and suppressed the subjective fatigue in male distance runners.

Correlation of Eccentric Strength, Reactive Strength, and Leg Stiffness With Running Economy in Well-Trained Distance Runners.

Li, F, Newton, RU, Shi, Y, Sutton, D, and Ding, H. Correlation of eccentric strength, reactive strength, and leg stiffness with running economy in well-trained distance runners. J Strength Cond Res 35(6): 1491-1499, 2021-Neuromuscular characteristics play a critical role in distance running performance; however, their relationship with running economy (RE) remains unclear. The purpose of this study was to evaluate the correlations between 1 repetition maximum (1RM) strength, eccentric strength, reactive strength, leg stiffness, and RE at 12-16 km·h-1 among well-trained male runners. Twenty-eight male collegiate distance runners participated in test sessions on 3 separate days. In the first session, their 1RM squat strength, countermovement jump (CMJ), and drop jump performances were measured. In the second session, the leg press (LP) eccentric and concentric peak force, and leg stiffness (Kleg) were evaluated. In the final session, 12, 14, and 16 km·h-1 RE, blood lactate concentration, and maximum oxygen uptake were measured. There were significant relationships between the LP eccentric peak force, eccentric:concentric peak force ratios (Efl:Cex), RE at speeds of 12, 14, and 16 km·h-1 (r = -0.527 to -0.630; p < 0.01), reactive strength index (r = -0.419 to -0.572; p < 0.05), and Kleg (r = -0.686 to -0.761; p < 0.001) were significantly correlated with RE at 12, 14, and 16 km·h-1. No significant association was found between LP concentric peak force, 1RM squat strength, CMJ, and RE at any speed (p > 0.05). Superior RE among distance runners may be related to greater eccentric strength, elastic energy utilization, and stiffer lower limbs during running but not to maximal muscle strength per se. Coaches should focus on these neuromuscular characteristics to improve running performance.

Bone geometry and lower extremity bone stress injuries in male runners

Bone stress injuries (BSI) are common among distance runners and research investigations examining risk factors for BSI among men are limited. Therefore, investigations are needed to determine if men with a history of BSI have skeletal properties that may heighten BSI incidence. ObjectivesTo analyze differences in bone density, bone geometry, and estimates of bone strength in male runners with and without a BSI history. DesignCross-sectional. MethodsWe recruited 36 male distance runners ages 18–41 for this study. We used peripheral quantitative computed tomography (pQCT) to assess volumetric bone mineral density (vBMD, mg/mm3), bone geometry (total and cortical bone area, mm2), tibia robustness (total area/tibia length, mm) and estimates of bone strength (section modulus and polar strength-strain index, mm3) at 5 tibial sites. ResultsAfter adjusting for age, the BSI group had more slender tibias (9%), lower stress strain indices (−16%), lower section moduli (−17%) and smaller total cross-sectional (−11%) and cortical areas (−12%) at the 66% site of the tibia compared with controls (P < 0.05 for all). Similar differences were found at all other measurement sites. After adjusting for body size, differences in bone outcomes remained significant at the 66% site. ConclusionsThese results indicate that men with a history of BSI have lower estimated bending strength compared to controls because of narrower tibias. However, differences are largely attenuated in the distal ½ of the tibia after adjusting for body size. Thus, smaller tibia size, particularly at the mid-diaphysis, may be an important indicator for BSI incidence.

Body Composition and Bone Mineral Density of Division 1 Collegiate Track and Field Athletes, a Consortium of College Athlete Research (C-CAR) Study

The purpose of the present study was to generate normative values for total and regional body composition in male and female Division 1 collegiate track and field athletes using dual X-ray absorptiometry. We also sought to examine body composition by event and sex. Data were used from the Consortium of College Athlete Research group. A total of 590 (male [M]/female [F] = 274/316) athletes had their height, weight, total and regional fat mass (FM), lean mass, and bone mineral density (BMD) measured. Athletes were classified into 1 of 7 categories: Jumps (M/F = 28/30); Long Distance (M/F = 104/110), Middle Distance (M/F = 27/24), Multievent (M/F = 11/9), Pole Vault (M/F = 21/27), Sprints (M/F = 54/96), and Throws (M/F = 29/20). Total and regional differences between events and sex were assessed by analysis of variance. Except for male and female throwers, all other track and field athletes’ mean percent body fat (M: 10.3%–12.6%, F: 17.5%–21.6%) and visceral FM (<500 g) was low, but in a healthy range. As expected, throwers had significantly (p < 0.05) higher total and regional FM and lean mass than other events. In addition, male (1.55 ± 0.11 g/cm2) and female (1.40 ± 0.12 g/cm2) throwers had significantly greater BMD than all other events while male (1.25 ± 0.10 g/cm2) and female (1.16 ± 0.09 g/cm2) distance runners had significantly lower BMD than all other events. In conclusion, track athletes’ body composition differed across events for both males and females. These measurements provide normative data on NCAA Division 1 male and female track and field athletes.

Prevalence and factors associated with asymptomatic Achilles tendon pathology in male distance runners

ObjectivesThis study investigated the prevalence of tendon pathology and associated factors in experienced, high mileage male endurance runners with no history of Achilles tendon pain. DesignCross-sectional study. SettingAchilles tendinopathy is a debilitating running injury affecting 50% of distance runners over their lifetime. It is diagnosed through a clinical examination and imaging, usually grey scale ultrasound (US) imaging. US imaging studies have shown that pathological changes can occur in asymptomatic individuals with no tendon pain. ParticipantsThirty seven male runners who had never had Achilles tendon pain. Main outcome measuresParticipants completed a running history survey, had their height, body mass, waist circumference, and ankle dorsiflexion range of movement (ROM) measured, and their tendons were assessed (normal, abnormal) using US imaging. ResultsAlmost half (46%) of these asymptomatic distance runners had at least one abnormal tendon. The runners with tendon pathology had significantly (p = 0.024) more years of running training (abnormal: median 20 years, interquartile range 6–25.5) than runners with no pathology (normal: median 7 years, interquartile range 5–15). No other significant differences between the groups were identified. ConclusionsAsymptomatic male distance runners had a high incidence of tendon pathology. Increased running years was associated with pathology in the Achilles tendon...

The Effects of Endurance Training Under Low Energy Availability on Muscle Glycogen Contents

PURPOSE:Some previous studies demonstrated that acute bout of exercise suppressed appetite and reduced energy intake among athletes. However, the accumulative effects of reduced energy intake during consecutive days of training period remains unclear. The purpose of the present study was to investigate the influences of 3 days of endurance training under low energy availability on muscle glycogen content, endocrine responses and endurance capacity. METHODS:Seven male long distance runners (19.9 ± 0.4 years, 175.6 ± 1.8 cm, 61.4 ± 2.0 kg, 67.5 ± 1.6 ml/kg/min) completed 3 consecutive days of endurance training under low energy availability trial (LEA, 18.9 ± 0.7 kcal/kg FFM/day) and normal energy availability trial (NEA, 52.9 ± 1.9 kcal/kg FFM/day). The order of two trials was randomized with two weeks interval between trials. The experiment consisted of 3 consecutive days of endurance training (days 1-3) and exercise performance test on the following morning (day 4). The endurance training consisted of 75 min of treadmill running at 70% of maximal oxygen uptake (VO2max) in both trials. Muscle glycogen contents, respiratory gas variables, subjective parameters, blood and urinal variables were evaluated in the morning during 3 days of training periods (day 1-day 3) and on the following morning after the training (day 4). As an indication of endurance capacity, time to exhaustion during submaximal running test was determined on day 4. RESULTS:LEA trial showed that body weight, free fat mass and skeletal muscle volume were significantly reduced during training period (P < 0.05). Also, muscle glycogen contents were significantly decreased in LEA (P < 0.001) with significant lower values than those in NEA trial (P < 0.001). Blood glucose, serum free testosterone and insulin like growth factor-1 concentrations were significant lowered with training under LEA (P < 0.05). On the other hand, serum leptin concentration did not change significantly in LEA trial during training period (P > 0.05). Time to exhaustion during submaximal running test evaluated on day 4 was not significantly different between LEA trial (1170 ± 127 s) and NEA trial (1361 ± 196 s, P > 0.05). CONCLUSION:Three consecutive days of endurance training under Low EA reduced muscle glycogen content. However, endurance capacity was not attenuated.

Effects of complex training versus heavy resistance training on neuromuscular adaptation, running economy and 5-km performance in well-trained distance runners.

BackgroundRecently, much attention has been paid to the role of neuromuscular function in long-distance running performance. Complex Training (CT) is a combination training method that alternates between performing heavy resistance exercises and plyometric exercises within one single session, resulting in great improvement in neuromuscular adaptation. The purpose of this study was to compare the effect of CT vs. heavy resistance training (HRT) on strength and power indicators, running economy (RE), and 5-km performance in well-trained male distance runners.MethodsTwenty-eight well-trained male distance runners (19–23 years old, VO2max:65.78 ± 4.99 ml.kg−1.min−1) performed one pre-test consisting of: maximum strength (1RM), counter movement jump (CMJ) height, peak power, a drop jump (DJ), and RE assessments, and blood lactate concentration (BLa) measurement at the speeds from 12–16 km.h−1, a 50-m sprint, and a 5-km running performance test. They were then divided into 3 groups: complex training group (CT, n = 10), that performed complex training and endurance training; heavy resistance training group (HRT, n = 9) that performed heavy strength training and endurance training; and control group (CON, n = 9) that performed strength-endurance training and endurance training. After the 8 weeks training intervention, all participants completed a post-test to investigate the training effects on the parameters measured.ResultsAfter training intervention, both the CT and HRT groups had improvements in: 1RM strength (16.88%, p < 0.001; 18.80%, p < 0.001, respectively), CMJ height (11.28%, p < 0.001; 8.96%, p < 0.001, respectively), 14 km.h−1RE (−7.68%, p < 0.001; −4.89%, p = 0.009, respectively), 50-m sprints (−2.26%, p = 0.003; −2.14%, p = 0.007, respectively) and 5-km running performance (−2.80%, p < 0.001; −2.09%, p < 0.001, respectively). The CON group did not show these improvements. All three training groups showed improvement in the 12 km.h−1RE (p ≤ 0.01). Only the CT group exhibited increases in DJ height (12.94%, p < 0.001), reactive strength index (19.99%, p < 0.001), 16 km.h−1 RE (−7.38%, p < 0.001), and a reduction of BLa concentrations at the speed of 16 km.h−1 (−40.80%, p < 0.001) between pre- and post-tests.ConclusionThis study demonstrated that CT can enhance 1RM strength, CMJ height, 12 and 14 km.h−1REs, 50-m sprints and 5-km running performances in well-trained male distance runners and may be superior to HRT for the development of reactive strength and 16 km.h−1RE, and reduction of BLa concentrations at speed of 16 km.h−1. Young male distance runners could integrate CT into their programs to improve the running performance.

Bone stress injuries in male distance runners: higher modified Female Athlete Triad Cumulative Risk Assessment scores predict increased rates of injury

ObjectivesBone stress injuries (BSI) are common in runners of both sexes. The purpose of this study was to determine if a modified Female Athlete Triad Cumulative Risk Assessment tool would...

Post-Activation Potentiation Increases Recruitment of Fast Twitch Fibers: A Potential Practical Application in Runners.

To determine the relationship between fatigue and post-activation potentiation, we examined the effects of sub-maximal continuous running on neuromuscular function tests, as well as on the squat jump and counter movement jump in endurance athletes. The height of the squat jump and counter movement jump and the estimate of the fast twitch fiber recruiting capabilities were assessed in seven male middle distance runners before and after 40 min of continuous running at an intensity corresponding to the individual lactate threshold. The same test was then repeated after three weeks of specific aerobic training. Since the three variables were strongly correlated, only the estimate of the fast twitch fiber was considered for the results. The subjects showed a significant improvement in the fast twitch fiber recruitment percentage after the 40 min run. Our data show that submaximal physical exercise determined a change in fast twitch muscle fiber recruitment patterns observed when subjects performed vertical jumps; however, this recruitment capacity was proportional to the subjects’ individual fast twitch muscle fiber profiles measured before the 40 min run. The results of the jump tests did not change significantly after the three-week training period. These results suggest that pre-fatigue methods, through sub-maximal exercises, could be used to take advantage of explosive capacity in middle-distance runners.

Interrelation between Exercise Heart Rate, Post-Run Systolic Blood Pressure, and Myocardial Structure in Distance Runners

Endurance running is an exercise practiced by athletes in many sports. Being benefi cial to health, it is also under-taken by a great number of non-athletic individuals. Rigorous endurance training frequently induces symmetric (i. e. both ventricular chamber dilation and wall thickening) myocardial hypertrophy, which is a physiological adapta-tion. Although distance running is a sport associated with haemodynamic volume rather than pressure overload, in addition to enlarged cardiac output, systolic arterial blood pressure also considerably increases during running. The extent of the cardiac hypertrophy was shown to be correlated with peak blood pressure measured during laboratory exercise. However, the predominant type of myocardial hypertrophy (the ratio between the myocardial wall thickness and chamber size) in endurance runners remains contradictory, and the majority of the responsible factors are still to be determined. The aim of this study was to determine possible correlations between post-run systolic blood pressure and myocardial hypertrophy in endurance runners.Standard transthoracic two-dimensional M-mode echocardiography was performed in white adult male distance runners (n = 49) of national level within four weeks of treadmill testing, which was a non-continuous incremental exercise test employed for the determination of the heart rate as well as post-exertional systolic blood pressure re-sponse. Runners’ training volume (evaluated as the average number of hours per week spent training averaged over the past four weeks) correlated (p &lt; 0.05) positively with the left ventricular (LV) wall thickness but not with the cavity size or LV mass (p &gt; 0.05). Training volume also positively correlated with systolic blood pressure response to exercise (p &lt; 0.05), but negatively with submaximal exercise heart rate (p &lt; 0.01). Post-run systolic blood pressure correlated positively with LV wall thickness and LV concentricity (namely, the ratio between the myocardial wall thick-ness and chamber size) (p &lt; 0.05), but no signifi cant correlation of any of the LV size parameters with resting heart rate, blood pressure, or systolic blood pressure in 2 to 4 min during the recovery period was revealed. Submaximal and maximal heart rate correlated signifi cantly and negatively with LV wall thickness, LV mass, and systolic blood pressure measured immediately after running (p &lt; 0.05).Training volume and post-run systolic blood pressure have been found to correlate positively with LV wall thickness and concentricity in white adult male distance runners. Negative correlation of exercise heart rate has been found with the post-exercise systolic blood pressure, LV wall thickness, and LV mass.Keywords: myocardial hypertrophy, pressure overload, echocardiography, athlete’s heart.

A Randomized Crossover Study Investigating the Running Economy of Highly-Trained Male and Female Distance Runners in Marathon Racing Shoes versus Track Spikes.

Running economy represents a complex interplay of physiological and biomechanical factors that are able to adapt chronically through training, or acutely through other interventions such as changes in footwear. The Nike Vaporfly (NVF) shoe was designed for marathon running on the roads and has been shown to improve running economy by ~ 4% compared with other marathon shoes, however, during track racing, distance runners traditionally wear a much lighter shoe with an embedded spike plate around the forefoot. The aim of this study was to determine if, and to what extent, the NVF shoes improve running economy compared with established track spikes (Nike Zoom Matumbo 3 [NZM]) and marathon racing shoes (Adidas Adizero Adios 3 [ADI]). Twenty-four highly-trained runners (12 male, 12 female) ran 4 × 5min trials on a treadmill while wearing each of the four shoe conditions: NVF, NZM, ADI, and the NVF matched in weight to the ADI shoe (NVF +), during three separate visits-visit 1: familiarization; visit 2: 14 and 18km·h-1 for men, 14 and 16km·h-1 for women; visit 3: 16km·h-1 for men, 15km·h-1 for women, plus a maximal rate of oxygen uptake (VO2max) test for both sexes. We measured the rates of oxygen uptake (VO2), carbon dioxide production and biomechanical measures while running at each velocity and shoe condition. The NVF shoe improved running economy by 2.6 ± 1.3% compared with the NZM, 4.2 ± 1.2% compared with ADI, and 2.9 ± 1.3% when matched in weight of the ADI shoe. Among the 24 subjects, the difference in running economy over the four velocities between the NVF and NZM shoes ranged from +0.50 to -5.34%, and -1.72 to -7.15% for NVF versus ADI. Correlations between changes in running economy and changes in biomechanical variables were either trivial or small, but unclear. The NVF enhanced running economy compared with track spikes and marathon shoes, and should be considered a viable shoe option for track and road racing.

Changes in Achilles tendon stiffness and energy cost following a prolonged run in trained distance runners.

During prolonged running, the magnitude of Achilles tendon (AT) length change may increase, resulting in increased tendon strain energy return with each step. AT elongation might also affect the magnitude of triceps surae (TS) muscle shortening and shortening velocity, requiring greater activation and increased muscle energy cost. Therefore, we aimed to quantify the tendon strain energy return and muscle energy cost necessary to allow energy storage to occur prior to and following prolonged running. 14 trained male (n = 10) and female (n = 4) distance runners (24±4 years, 1.72±0.09 m, 61±10 kg, 64.6±5.8 ml•kg-1•min-1) ran 90 minutes (RUN) at approximately 85% of lactate threshold speed (sLT). Prior to and following RUN, AT stiffness and running energy cost (Erun) at 85% sLT were determined. AT energy return was calculated from AT stiffness, measured with dynamometry and ultrasound and estimated TS force during stance. TS energy cost was estimated on the basis of AT force and assumed crossbridge mechanics and energetics. Following RUN, AT stiffness was reduced from 328±172 N•mm-1 to 299±148 N•mm-1 (p = 0.022). Erun increased from 4.56±0.32 J•kg-1•m-1 to 4.62±0.32 J•kg-1•m-1 (p = 0.049). Estimated AT energy return was not different following RUN (p = 0.99). Estimated TS muscle energy cost increased significantly by 11.8±12.3 J•stride-1, (p = 0.0034), accounting for much of the post-RUN increase in Erun (8.6±14.5 J•stride-1,r2 = 0.31). These results demonstrate that a prolonged, submaximal run can reduce AT stiffness and increase Erun in trained runners, and that the elevated TS energy cost contributes substantially to the elevated Erun.

Efficacy of depth jumps to elicit a post-activation performance enhancement in junior endurance runners

ObjectivesTo determine the effect of performing depth jumps (DJ) pre-exercise on running economy (RE) and time to exhaustion (TTE) at the speed associated with maximal oxygen uptake (sV˙O2max) in a group of high-performing junior middle-distance runners. DesignRandomized crossover study. MethodsSeventeen national- and international-standard male distance runners (17.6±1.2years, 63.4±6.3kg, 1.76±0.06m, 70.7±5.2mLkg−1min−1) completed two trials. Following a 5min warm-up at 60% V˙O2max, participants performed a 5min run at 20%Δ below oxygen uptake corresponding with lactate turn-point to determine pre-intervention RE. Participants then completed either six DJ from a box equivalent to their best counter-movement jump (CMJ) or a control condition (C) involving body weight quarter squats. After a 10min passive recovery, another 5min sub-maximal run was performed followed by a run to exhaustion at sV˙O2max. ResultsCompared to the C trial, DJ produced moderate improvements (−3.7%, 95% confidence interval for effect size: 0.25–1.09) in RE, which within the context of minimal detectable change is considered possibly beneficial. Differences in TTE and other physiological variables were most likely trivial (ES: <0.2). Individual responses were small, however a partial correlation revealed a moderate relationship (r=−0.55, p=0.028) between change in RE and CMJ height. ConclusionsThe inclusion of a set of six DJ in the warm-up routine of a well-trained young male middle-distance runner is likely to provide a moderate improvement in RE.

P118-The clinical use of an Asymmetry Index (AI) calculated from Centre of Mass data to distinguish between normal and pathological gait

We have recently demonstrated that the triceps surae muscles energy cost (ECTS) represents a substantial portion of the total metabolic cost of running (Erun). Therefore, it seems relevant to evaluate the factors which dictate ECTS, namely the amount and velocity of shortening, since it is likely these factors will dictate Erun. Erun and triceps surae morphological and AT mechanical properties were obtained in 46 trained and elite male and female distance runners using ultrasonography and dynamometry. ECTS (J·stride−1) at the speed of lactate threshold (sLT) was estimated from AT force and crossbridge mechanics and energetics. To estimate the relative impact of these factors on ECTS, mean values for running speed, body mass, resting fascicle length (Lf), Achilles tendon stiffness and moment arm and maximum isometric plantarflexion torque were obtained. ECTS was calculated across a range (mean ± 1 sd) of values for each independent factor. Average sLT was 233 m·min−1. At this speed, ECTS was 255 J·stride−1. Estimated fascicle shortening velocity was 0.08 Vmax and the level of muscle activation was 84.7% of maximum isometric torque. Compared to the ECTS calculated from the lowest range of values obtained for each independent factor, higher AT stiffness was associated with a 39% reduction in ECTS, 81% reduction in fascicle shortening velocity and a 31% reduction in muscle activation. Longer AT moment arms and elevated body masses were associated with an increase in ECTS of 18% and 23%, respectively. These results demonstrate that a low ECTS is achieved primarily from a high AT stiffness and low body mass, which is exemplified in elite distance runners.

Shorter Ground Contact Time and Better Running Economy: Evidence From Female Kenyan Runners.

Mooses, M, Haile, DW, Ojiambo, R, Sang, M, Mooses, K, Lane, AR, and Hackney, AC. Shorter ground contact time and better running economy: evidence from female Kenyan runners. J Strength Cond Res 35(2): 481-486, 2021-Previously, it has been concluded that the improvement in running economy (RE) might be considered as a key to the continued improvement in performance when no further increase in V̇o2max is observed. To date, RE has been extensively studied among male East African distance runners. By contrast, there is a paucity of data on the RE of female East African runners. A total of 10 female Kenyan runners performed 3 × 1,600-m steady-state run trials on a flat outdoor clay track (400-m lap) at the intensities that corresponded to their everyday training intensities for easy, moderate, and fast running. Running economy together with gait characteristics was determined. Subjects showed moderate to very good RE at the first (202 ± 26 ml·kg-1·km-1) and second (188 ± 12 ml·kg-1·km-1) run trials, respectively. Correlation analysis revealed significant relationship between ground contact time (GCT) and RE at the second run (r = 0.782; p = 0.022), which represented the intensity of anaerobic threshold. This study is the first to report the RE and gait characteristics of East African female athletes measured under everyday training settings. We provided the evidence that GCT is associated with the superior RE of the female Kenyan runners.

Resistance Training Is Associated With Higher Bone Mineral Density Among Young Adult Male Distance Runners Independent of Physiological Factors.

Duplanty, AA, Levitt, DE, Hill, DW, McFarlin, BK, DiMarco, NM, and Vingren, JL. Resistance training is associated with higher bone mineral density among young adult male distance runners independent of physiological factors. J Strength Cond Res 32(6): 1594-1600, 2018-Low bone mineral density (BMD) in male distance runners is common and could be modulated by a host of biomarkers involved in the dynamic balance of bone tissue. In contrast, resistance training can increase BMD; however, the efficacy of resistance training in protecting BMD in distance runners has not been elucidated. The aim of this study was to investigate the relationship between resistance training, testosterone and bone metabolism biomarker concentrations, and BMD in young adult male distance runners. Twenty-five apparently healthy men (23-32 years; mean ± SD: 25.9 ± 2.9 years; 1.77 ± 0.04 m; 75.4 ± 8.5 kg) were categorized into 1 of 3 groups: untrained control participants (CON; n = 8); nonresistance-trained runners (NRT; n = 8); or resistance-trained runners (RT; n = 9). Blood was collected and analyzed for concentrations of free and total testosterone and 14 bone metabolism biomarkers. Bone mineral density was assessed using dual-energy X-ray absorptiometry. At all measured sites, BMD was greater (p ≤ 0.05) for RT compared with NRT and CON. Vitamin D concentration was greater (p ≤ 0.05) in RT and NRT compared with CON. Concentrations of testosterone and remaining bone biomarkers did not differ between groups (p > 0.05). Resistance-trained runners had greater BMD than nonresistance-trained runners and untrained peers. This difference did not seem to be modulated by biomarkers that contribute to bone formation or resorption, indicating that differences in BMD are associated with habitual load-bearing exercise using external resistance. Runners should perform resistance exercise at least once per week because this is associated with greater BMD.

Effect Of Low Energy Availability During Three Consecutive Days Of Endurance Training On Muscle Glycogen Contents And Serum Hepcidin Levels In Male Long Distance Runners.

Effect Of Low Energy Availability During Three Consecutive Days Of Endurance Training On Muscle Glycogen Contents And Serum Hepcidin Levels In Male Long Distance Runners.