The effects of wearing face masks on the perception and mood of male healthy male adults during treadmill running: A pilot study.

In the past few years, the face mask has been recommended for the prevention of exposing others to COVID-19. Wearing a face mask may have the potential to increase dyspnea and discomfort during exercise; however, controversy exists on whether wearing face masks during exercise affects exercise performance, perception, and mood in runners. We investigated the physiological and perceptual responses of healthy male adults who had experienced long-distance running while exercising at different intensities. Nine healthy young adults who were long-distance runners wearing surgical face mask conducted an incremental treadmill protocol. The protocol was three 6-min stages (20%, 40%, and 60% of maximal heart rate, respectively). The rating of perceived exertion (RPE) and the feeling scale (FS) were measured. RPE was higher in mask condition than in unmask condition (No mask vs. Face mask, light; 8.22 vs. 8.78, p = 0.615, middle; 10.00 vs. 10.78, p = 0.345, high; 12.33 vs. 13.67, p = 0.044.), while FS was not different between conditions. The present study shows that wearing a mask may increase rating of perceived exertion and discomfort when the exercise intensity exceeds a certain threshold in healthy male adults who have experienced long-distance running.

Risk factors associated with a history of iliotibial band syndrome (hITBS) in distance runners: a cross-sectional study in 76 654 race entrants - a SAFER XXXIII study.

BACKGROUND: Despite the numerous health benefits of distance running, it is also associated with the development of 'gradual onset running-related injuries' (GORRIs) one of which is Iliotibial Band Syndrome (ITBS). Novel risk factors associated with a history of ITBS (hITBS) have not been described in a large cohort of distance runners. OBJECTIVE: To identify risk factors associated with hITBS in distance runners. DESIGN: Descriptive cross-sectional study. SETTING: 21.1 km and 56 km Two Oceans Marathon races (2012-2015). PARTICIPANTS: 106 743 race entrants completed the online pre-race medical screening questionnaire. A total of 1 314 runners confirmed an accurate hITBS diagnosis. METHODS: Selected risk factors associated with hITBS explored included: demographics (race distance, sex, age groups), training/running variables, history of existing chronic diseases (including a composite chronic disease score) and history of any allergy. Prevalence (%) and prevalence ratios (PR; 95% CI) are reported (uni- & multiple regression analyzes). RESULTS: 1.63% entrants reported hITBS in a 12-month period. There was a higher (p < 0.0001) prevalence of hITBS in the longer race distance entrants (56 km), females, younger entrants, fewer years of recreational running (PR = 1.07; p = 0.0009) and faster average running speed (PR = 1.02; p = 0.0066). When adjusted for race distance, sex, age groups, a higher chronic disease composite score (PR = 2.38 times increased risk for every two additional chronic diseases; p < 0.0001) and a history of allergies (PR = 1.9; p < 0.0001) were independent risk factors associated with hITBS. CONCLUSION: Apart from female sex, younger age, fewer years of running and slower running speed, two novel independent risk factors associated with hITBS in distance runners are an increased number of chronic diseases and a history of allergies. Identifying athletes at higher risk for ITBS can guide healthcare professionals in their prevention and rehabilitation efforts.

Stride-to-stride variability and fluctuations at intensities around lactate threshold in distance runners.

Stride-to-stride variability and fluctuations in running have been widely investigated in relation to fatigue, injury, and other factors. However, no studies have examined the relationship of stride-to-stride variability and fluctuations with lactate threshold (LT), a well-known performance indicator for distance runners that represents the threshold at which fast-twitch muscle fibers are activated and the glycolytic system is hyperactivated. In this study, we examined a relationship between LT and stride-to-stride variability and fluctuations in trained middle- and long-distance runners (n = 33). All runners were asked to perform multistage graded exercise tests while wearing accelerometers on the upper surface of their shoes. The LT was determined by measuring blood lactate concentrations after each stage. Three gait parameters for each step were calculated based on the acceleration data: stride time (ST), ground contact time (CT), and peak acceleration (PA). The coefficient of variation (CV) and the long-range correlations (α) for each parameter were also calculated. The effects of the runner's group and the relative intensity for CV and α on gait parameters were evaluated using a two-way repeated measures analysis of variance. Although no significant effect was observed in the CV and α of ST, significant intensity main effects were observed for the CV and α of CT and PA. The lack of significant changes in ST might be the result of runners' adequate control of ST to minimize energy cost. All the parameters showing significant changes with increasing intensity decreased dramatically when they were close to LT. This might have been caused by an increase in physiological load near LT and be interpreted as a variation in motor control because of alternations in the mobilized muscle fibers and physiological changes around the LT. The α should be useful for non-invasive LT detection.

Does an Asian-based Diet Sufficient to Meet the Nutritional Demands of Endurance Athletes?: A Cross-sectional Study

@#Introduction: Limited studies have examined the dietary intake pattern of Malaysian endurance athletes. Differences in the types of foods consumed between Malaysian and Western population leads to varying nutritional intake values. This study aimed to characterise the dietary intake of Malaysian endurance athletes as compared to sports nutrition recommendations, and to determine the associations between participants’ backgrounds and macronutrients intake status. Methods: A total of 85 endurance-trained Malaysian athletes participated in a cross-sectional study. Dietary intake for three days throughout the training season was evaluated using 24-hour dietary recall. The macronutrients and micronutrients intakes were compared to the nutritional recommendation for athletes and the Recommended Nutrient Intakes (RNI), respectively. The food serving size was compared to the Malaysian Food Pyramid 2020. Results: Of all participants, 51% met the minimum recommendations for carbohydrate (CHO) intake (6g/ kg/day). For protein intake, 88% of participants had surpassed the lower limit of 1.2g/kg/day. The lower limit of fat intake (20% of total daily energy intake) was met by 99% of the participants. Most of the participants had a suboptimal intake of calcium, vitamin A, and vitamin E, while all had inadequate vitamin D intake. The athletes’ institution was significantly associated with the CHO intake status. Also, the athletes’ institution and the highest education level were significantly associated with the protein intake status. Conclusion: Athletes who practised Asian-based diets were able to achieve the energy, protein, and fat intake recommendations. However, there was a suboptimal intake of the CHO and micronutrients as compared to the recommendations.

Heavy Resistance Training Versus Plyometric Training for Improving Running Economy and Running Time Trial Performance: A Systematic Review and Meta-analysis.

BACKGROUND: As an adjunct to running training, heavy resistance and plyometric training have recently drawn attention as potential training modalities that improve running economy and running time trial performance. However, the comparative effectiveness is unknown. The present systematic review and meta-analysis aimed to determine if there are different effects of heavy resistance training versus plyometric training as an adjunct to running training on running economy and running time trial performance in long-distance runners. METHODS: Electronic databases of PubMed, Web of Science, and SPORTDiscus were searched. Twenty-two studies completely satisfied the selection criteria. Data on running economy and running time trial performance were extracted for the meta-analysis. Subgroup analyses were performed with selected potential moderators. RESULTS: The pooled effect size for running economy in heavy resistance training was greater (g = - 0.32 [95% confidence intervals [CIs] - 0.55 to - 0.10]: effect size = small) than that in plyometric training (g = -0.13 [95% CIs - 0.47 to 0.21]: trivial). The effect on running time trial performance was also larger in heavy resistance training (g = - 0.24 [95% CIs - 1.04 to - 0.55]: small) than that in plyometric training (g = - 0.17 [95% CIs - 0.27 to - 0.06]: trivial). Heavy resistance training with nearly maximal loads (≥ 90% of 1 repetition maximum [1RM], g = - 0.31 [95% CIs - 0.61 to - 0.02]: small) provided greater effects than those with lower loads (< 90% 1RM, g = - 0.17 [95% CIs - 1.05 to 0.70]: trivial). Greater effects were evident when training was performed for a longer period in both heavy resistance (10-14 weeks, g = - 0.45 [95% CIs - 0.83 to - 0.08]: small vs. 6-8 weeks, g = - 0.21 [95% CIs - 0.56 to 0.15]: small) and plyometric training (8-10 weeks, g = 0.26 [95% CIs - 0.67 to 0.15]: small vs. 4-6 weeks, g = - 0.06 [95% CIs 0.67 to 0.55]: trivial). CONCLUSIONS: Heavy resistance training, especially with nearly maximal loads, may be superior to plyometric training in improving running economy and running time trial performance. In addition, running economy appears to be improved better when training is performed for a longer period in both heavy resistance and plyometric training.

Effect of a Multi-Strain Probiotic Supplement on Gastrointestinal Symptoms and Serum Biochemical Parameters of Long-Distance Runners: A Randomized Controlled Trial.

As many as 70% of athletes who practice endurance sports report experiencing gastrointestinal (GI) symptoms, such as abdominal pain, intestinal gurgling or splashing (borborygmus), diarrhea or the presence of blood in the stool, that occur during or after intense physical exercise. The aim of the study was to evaluate the effect of a multi-strain probiotic on the incidence of gastrointestinal symptoms and selected biochemical parameters in the serum of long-distance runners. After a 3-month intervention with a multi-strain probiotic, a high percentage of runners reported subjective improvement in their general health. Moreover, a lower incidence of constipation was observed. In the group of women using the probiotic, a statistically significant (p = 0.035) increase in serum HDL cholesterol concentration and a favorable lower concentration of LDL cholesterol and triglycerides were observed. These changes were not observed in the group of men using the probiotic. Probiotic therapy may reduce the incidence and severity of selected gastrointestinal symptoms in long-distance runners and improve subjectively assessed health condition.

Training intensity distribution on running time in amateur endurance runners: a scoping review / Distribución de intensidades de entrenamiento sobre el tiempo de carrera en corredores recreativos de resistencia: revisión de alcance

Problem: Intensity in endurance training is important for improving race time; its optimal handling in amateur runners has not been extensively studied. The polarized training intensity distribution (TID) model emerges as a possibility to reduce race time; however, effect of this model remains to be demonstrated compared to other TID models. Objective: The objective of this study is to explore the current state of the evidence and its the gaps, according to the effect of the polarized TID model on race time in amateur runners compared to other TID models. Method: A scoping review without date restrictions was carried out in PubMed, EBSCO, SciELO, LILACS, and Google Scholar. Randomized controlled studies, quasi-experimental studies, and case studies, which comprise polarized TID model in amateur runners on race time, were include. Results: Five studies evaluated the effect on running time using the polarized TID model compared to other models in amateur runners; four of them did not show differences between groups in the race times in two, five, and ten km. Only one study showed significant diferences in the race time at 21 km. Conclusions: The model with polarized TID did not show significant differences in race time compared to other models, except for a case report in which the polarized TID was higher by 21 km compared to the threshold TID: 1 hour. 20 min. 22 seconds and 1 hour. 26 min. 34s, respectively. The scarce evidence found, the heterogeneity in the distances in the evaluated race time, the distribution of zones in the same TID, the duration of the interventions, and the monitoring of the loads, are the main limitations found in the studies. The polarized TID could contribute to adherence, lower perception of effort, and injury prevention. However, this must be tested in future studies.

Problema: La intensidad en el entrenamiento de la resistencia es importante para mejorar el tiempo de carrera; su manipulación óptima en corredores recreativos no ha sido estudiada ampliamente. El modelo de distribución de intensidad del entrenamiento (DIE) polarizado emerge como posibilidad para reducir el tiempo de carrera. Sin embargo, falta demostrar su efecto comparado con otros modelos de DIE. Objetivo: Explorar el estado actual de la evidencia científica y sus vacíos respecto al efecto del modelo de DIE polarizado sobre el tiempo de carrera en corredores recreativos, en comparación con otros modelos de DIE. Método: Se realizó una revisión de alcance sin restricción de fechas en PubMed, EBSCO, SciELO, LILACS y Google Scholar. Se incluyeron estudios controlados aleatorios, estudios cuasiexperimentales y estudios de caso, que tuvieran como DIE el modelo polarizado en corredores recreativos sobre el tiempo de carrera. Resultados: Cinco estudios evaluaron el efecto en el tiempo de carrera usando el modelo de DIE polarizado comparado con otros modelos en corredores recreativos; cuatro de ellos no mostraron diferencias entre grupos en los tiempos de carrera en dos, cinco y diez km. Solo un estudio mostró diferencias significativas en el tiempo de carrera en 21 km. Conclusiones: El modelo con DIE polarizado no mostró diferencias significativas en el tiempo de carrera comparado con otros modelos, a excepción de un reporte de caso en el cual la DIE polarizado fue superior en 21 km comparado la DIE umbral: 1 hora. 20 min. 22 s y 1 hora. 26 min. 34 s, respectivamente. La escasa evidencia encontrada, la heterogeneidad en las distancias en el tiempo de carrera evaluado, la distribución de zonas en una misma DIE, la duración de las intervenciones y la monitorización de las cargas son las principales limitaciones encontradas en los estudios. La DIE polarizado podría contribuir a la adherencia, a una menor percepción del esfuerzo y a la prevención de lesiones. No obstante, esto debe ser probado en estudios futuros.

Effects of Co-Ingestion of ß-Hydroxy-ß-Methylbutyrate and L-Arginine α-Ketoglutarate on Jump Performance in Young Track and Field Athletes.

The aim of the study was to determine the effect of simultaneous supplementation of ß-hydroxy-ß-methylbutyrate and L-Arginine α-ketoglutarate on lower limb power and muscle damage in medium distance runners aged 15.3 (±0.9) years old. METHODS: The study group consisted of 40 volunteers aged 14-17 years practicing medium distance running for at least two years. The study lasted 12 days and followed a randomized, double-blind, placebo-controlled, parallel design. All subjects attended a familiarization session on day 0 before the test. The subjects were randomly divided into two groups: supplements and placebo group. The same training cycle protocol was used in both groups during the 12-day training period. Morning warm-up involved 10 min jogging at 60-75% of maximal heart rate and countermovement jump height measurement. Main training units were carried out for both groups with the same volume. Training load assessment (the daily session Rating of Perceived Exertion (s-RPE) method) method takes into consideration the intensity and the duration of the training session to calculate the "training load" (TL). RESULTS: At the end of the training cycle, a significant (p = 0.002) decrease in the countermovement jump (CMJ) height was found in the placebo group when compared to the baseline. In the supplement group, there was no decrease in the countermovement jump height. Creatine kinase and lactate dehydrogenase concentration increased during the training days similarly in both groups and decreased on rest days. There were no differences between groups in enzymes concentration. The research results indicate that the supplement combination used in the supplements group prevented a reduction in the CMJ values. In contrast to the supplements group, in the placebo group, the CMJ changes were statistically significant: a noticeable (p = 0.002) decrease in CMJ was noted between the baseline measurement and the 6th measurement. The well-being of the subjects from both groups changed significantly during the training period, and the intergroup differences in the mood level were similar and not statistically significant. CONCLUSIONS: The results of this study indicate that the daily co-supplementation with calcium salt of ß-hydroxy-ß-methylbutyrate (7.5 g) and L-Arginine α-ketoglutarate (10 g) during training might help to prevent decline in jump performance. No influence on muscle damage markers or mood was shown.

Pacing strategies during male 1500 m running world record performances.

The aim was to determine the pacing strategies used to achieve male 1500 m running world record performances. Lap times (three first laps and the last 300 m) for the last 37 male 1500 m world record performances achieved since 1917 until 1998 were collected. An analysis of variance with repeated measures and a Bonferroni post hoc test were conducted to determine differences between the percentages of race average speed at each lap. Lap 1 and last 300 m differed from lap 2 and 3, being the latter slower (P < 0.001, 1.44 ≤ ES ≤ 1.95), and displaying a U-shaped pacing profile. Whereas the pacing strategies observed differed from those previously determined for major championship races, a fast endspurt was always present and therefore athletes aiming for a world standard performance should train for developing their anaerobic capacity in addition to a high aerobic power.

Effects of Isometric Exercises versus Static Stretching in Warm-up Regimens for Running Sport Athletes: A Systematic Review.

The objective of this review was to identify studies that report the pre-exercise effects of isometric exercise versus static stretching on performance and injury rates of running athletes in comparison to their outcomes. Seven electronic databases were searched: Cochrane, PEDro, CINAHL, PubMed, MEDLINE, SportDiscus, and GoogleScholar. Data was collected using an established PICO question, and assembled logic grid. The included articles were required to (1) assess running performance or injury prevention and (2) include isometric exercises/muscle activation and/or static stretching. Articles published prior to the year 2000, non-English, and non-human studies were excluded. Quality was assessed using the PEDro quality appraisal tool for RCTs, and NIH-NHLBI appraisal tool for others. The Cochrane collaboration tool for risk of bias as well as the PRISMA 2020 statement were also used in this review. In the nine articles appraised in the study, variables assessed included running economy, injury rate, soreness levels, sprint times, and countermovement and drop jump height. Static stretching demonstrated a significant negative effect on sprint performance and countermovement/drop jump height. It also demonstrated a decrease in variables associated with injury over extended periods and no impact on running economy. Isometric holds demonstrated no significant effect on sprint performance or countermovement/drop jump height. It also demonstrated decreases in soreness levels and no impact on running economy. Isometric holds have positive effects/fewer negative results on running athletes when compared to static stretching for pre-exercise performance. Research with decreased risk of bias is needed to determine maximal benefits from timing/dosage of isometric hold in warm-up.

Triceps Surae Muscle-Tendon Properties as Determinants of the Metabolic Cost in Trained Long-Distance Runners.

Purpose: This study aimed to determine whether triceps surae's muscle architecture and Achilles tendon parameters are related to running metabolic cost (C) in trained long-distance runners. Methods: Seventeen trained male recreational long-distance runners (mean age = 34 years) participated in this study. C was measured during submaximal steady-state running (5 min) at 12 and 16 km h-1 on a treadmill. Ultrasound was used to determine the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and soleus (SO) muscle architecture, including fascicle length (FL) and pennation angle (PA), and the Achilles tendon cross-sectional area (CSA), resting length and elongation as a function of plantar flexion torque during maximal voluntary plantar flexion. Achilles tendon mechanical (force, elongation, and stiffness) and material (stress, strain, and Young's modulus) properties were determined. Stepwise multiple linear regressions were used to determine the relationship between independent variables (tendon resting length, CSA, force, elongation, stiffness, stress, strain, Young's modulus, and FL and PA of triceps surae muscles) and C (J kg-1m-1) at 12 and 16 km h-1. Results: SO PA and Achilles tendon CSA were negatively associated with C (r 2 = 0.69; p < 0.001) at 12 km h-1, whereas SO PA was negatively and Achilles tendon stress was positively associated with C (r 2 = 0.63; p = 0.001) at 16 km h-1, respectively. Our results presented a small power, and the multiple linear regression's cause-effect relation was limited due to the low sample size. Conclusion: For a given muscle length, greater SO PA, probably related to short muscle fibers and to a large physiological cross-sectional area, may be beneficial to C. Larger Achilles tendon CSA may determine a better force distribution per tendon area, thereby reducing tendon stress and C at submaximal speeds (12 and 16 km h-1). Furthermore, Achilles tendon morphological and mechanical properties (CSA, stress, and Young's modulus) and triceps surae muscle architecture (GM PA, GM FL, SO PA, and SO FL) presented large correlations with C.

Predictive Performance Models in Long-Distance Runners: A Narrative Review.

Physiological variables such as maximal oxygen uptake (VO2max), velocity at maximal oxygen uptake (vVO2max), running economy (RE) and changes in lactate levels are considered the main factors determining performance in long-distance races. The aim of this review was to present the mathematical models available in the literature to estimate performance in the 5000 m, 10,000 m, half-marathon and marathon events. Eighty-eight articles were identified, selections were made based on the inclusion criteria and the full text of the articles were obtained. The articles were reviewed and categorized according to demographic, anthropometric, exercise physiology and field test variables were also included by athletic specialty. A total of 58 studies were included, from 1983 to the present, distributed in the following categories: 12 in the 5000 m, 13 in the 10,000 m, 12 in the half-marathon and 21 in the marathon. A total of 136 independent variables associated with performance in long-distance races were considered, 43.4% of which pertained to variables derived from the evaluation of aerobic metabolism, 26.5% to variables associated with training load and 20.6% to anthropometric variables, body composition and somatotype components. The most closely associated variables in the prediction models for the half and full marathon specialties were the variables obtained from the laboratory tests (VO2max, vVO2max), training variables (training pace, training load) and anthropometric variables (fat mass, skinfolds). A large gap exists in predicting time in long-distance races, based on field tests. Physiological effort assessments are almost exclusive to shorter specialties (5000 m and 10,000 m). The predictor variables of the half-marathon are mainly anthropometric, but with moderate coefficients of determination. The variables of note in the marathon category are fundamentally those associated with training and those derived from physiological evaluation and anthropometric parameters.

The Free Achilles Tendon Is Shorter, Stiffer, Has Larger Cross-Sectional Area and Longer T2* Relaxation Time in Trained Middle-Distance Runners Compared to Healthy Controls.

Tendon geometry and tissue properties are important determinants of tendon function and injury risk and are altered in response to ageing, disease, and physical activity levels. The purpose of this study was to compare free Achilles tendon geometry and mechanical properties between trained elite/sub-elite middle-distance runners and a healthy control group. Magnetic resonance imaging (MRI) was used to measure free Achilles tendon volume, length, average cross-sectional area (CSA), regional CSA, moment arm, and T2* relaxation time at rest, while freehand three-dimensional ultrasound (3DUS) was used to quantify free Achilles tendon mechanical stiffness, Young's modulus, and length normalised mechanical stiffness. The free Achilles tendon in trained runners was significantly shorter and the average and regional CSA (distal end) were significantly larger compared to the control group. Mechanical stiffness of the free Achilles tendon was also significantly higher in trained runners compared to controls, which was explained by the group differences in tendon CSA and length. T2* relaxation time was significantly longer in trained middle-distance runners when compared to healthy controls. There was no relationship between T2* relaxation time and Young's modulus. The longer T2* relaxation time in trained runners may be indicative of accumulated damage, disorganised collagen, and increased water content in the free Achilles tendon. A short free Achilles tendon with large CSA and higher mechanical stiffness may enable trained runners to rapidly transfer high muscle forces and possibly reduce the risk of tendon damage from mechanical fatigue.

Interval Hypoxic Training Enhances Athletic Performance and Does Not Adversely Affect Immune Function in Middle- and Long-Distance Runners.

This study evaluated the effects of intermittent interval training in hypoxic conditions for six weeks compared with normoxic conditions, on hemodynamic function, autonomic nervous system (ANS) function, immune function, and athletic performance in middle- and long-distance runners. Twenty athletes were divided into normoxic training (normoxic training group (NTG); n = 10; residing and training at sea level) and hypoxic training (hypoxic training group (HTG); n = 10; residing at sea level but training in 526-mmHg hypobaric hypoxia) groups. All dependent variables were measured before, and after, training. The training frequency was 90 min, 3 d per week for six weeks. Body composition showed no significant difference between the two groups. However, the HTG showed more significantly improved athletic performance (e.g., maximal oxygen uptake). The hemodynamic function (e.g., oxygen uptake, oxygen pulse, and cardiac output) during submaximal exercise and ANS function (e.g., standard deviation and root mean square of successive differences, high frequency, and low/high frequency) improved more in the HTG. Immune function parameters were stable within the normal range before and after training in both groups. Therefore, hypoxic training was more effective in enhancing athletic performance, and improving hemodynamic and ANS function; further, it did not adversely affect immune function in competitive runners.

Compulsive exercise and weight suppression: Associations with eating pathology in distance runners.

Some athletes, particularly those who participate in activities that emphasize leanness such as competitive running, are at greater risk for eating disorder (ED) pathology. Compulsive exercise (CE) is linked with ED pathology among female athletes, with evidence that CE for weight control is most strongly correlated with ED thoughts and behaviors. Weight suppression (WS), the discrepancy between highest adult weight and current weight, is also linked with ED symptoms. Taken together, runners with greater WS may be more likely to engage in CE to influence their weight or shape and may subsequently report other associated ED symptoms. As such, the current study investigated associations between CE and ED pathology in a mixed-gender sample of adult distance runners (N = 277, 51% female), and tested the impact of WS on this association. Results indicated that females reported greater CE and ED pathology, whereas males reported greater WS. A significant interaction effect for CE x WS, (p < .05) indicated that the relation between CE and ED scores was stronger among male runners who reported higher WS. In contrast, WS did not impact the association between CE and ED pathology for female runners. Results from the current study have important implications for the assessment and treatment of ED in athletes, specifically runners, and suggest that WS is an important factor to consider when working with male athletes.

Cooper Test Provides Better Half-Marathon Performance Prediction in Recreational Runners Than Laboratory Tests.

This study compared the ability to predict performance in half-marathon races through physiological variables obtained in a laboratory test and performance variables obtained in the Cooper field test. Twenty-three participants (age: 41.6 ± 7.6 years, weight: 70.4 ± 8.1 kg, and height: 172.5 ± 6.3 cm) underwent body composition assessment and performed a maximum incremental graded exercise laboratory test to evaluate maximum aerobic power and associated cardiorespiratory and metabolic variables. Cooper's original protocol was performed on an athletic track and the variables recorded were covered distance, rating of perceived exertion, and maximum heart rate. The week following the Cooper test, all participants completed a half-marathon race at the maximum possible speed. The associations between the laboratory and field tests and the final time of the test were used to select the predictive variables included in a stepwise multiple regression analysis, which used the race time in the half marathon as the dependent variable and the laboratory variables or field tests as independent variables. Subsequently, a concordance analysis was carried out between the estimated and actual times through the Bland-Altman procedure. Significant correlations were found between the time in the half marathon and the distance in the Cooper test (r = -0.93; p < 0.001), body weight (r = 0.40; p < 0.04), velocity at ventilatory threshold 1, (r = -0.72; p < 0.0001), speed reached at maximum oxygen consumption (vVO2max), (r = -0.84; p < 0.0001), oxygen consumption at ventilatory threshold 2 (VO2VT2) (r = -0.79; p < 0.0001), and VO2max (r = -0.64; p < 0.05). The distance covered in the Cooper test was the best predictor of time in the half-marathon, and might predicted by the equation: Race time (min) = 201.26 - 0.03433 (Cooper test in m) (R 2 = 0.873, SEE: 3.78 min). In the laboratory model, vVO2max, and body weight presented an R 2 = 0.77, SEE 5.28 min. predicted by equation: Race time (min) = 156.7177 - 4.7194 (vVO2max) - 0.3435 (Weight). Concordance analysis showed no differences between the times predicted in the models the and actual times. The data indicated a high predictive power of half marathon race time both from the distance in the Cooper test and vVO2max in the laboratory. However, the variable associated with the Cooper test had better predictive ability than the treadmill test variables. Finally, it is important to note that these data may only be extrapolated to recreational male runners.

Magnetic Resonance Imaging and Freehand 3-D Ultrasound Provide Similar Estimates of Free Achilles Tendon Shape and 3-D Geometry.

The purpose of this study was to assess the similarity of free Achilles tendon shape and 3-D geometry between magnetic resonance imaging (MRI) and freehand 3-D ultrasound (3-DUS) imaging methods. Fourteen elite/sub-elite middle-distance runners participated in the study. MRI and 3-DUS scans of the Achilles tendon were acquired on two separate imaging sessions, and all 3-D reconstructions were performed using identical methods. Shape similarity of free Achilles tendon reconstructed from MRI and 3-DUS data was assessed using Jaccard index, Hausdorff distance and root mean square error (RMSE). The Jaccard index, Hausdorff distance and RMSE values were 0.76 ± 0.05, 2.70 ± 0.70 and 0.61 ± 0.10 mm, respectively. The level of agreement between MRI and 3-DUS for free Achilles tendon volume, length and average cross-sectional area (CSA) was assessed using Bland-Altman analysis. Compared to MRI, freehand 3-DUS overestimated volume, length and average CSA by 30.6 ± 15.8 mm3 (1.1% ± 0.6%), 0.3 ± 0.7 mm (0.6% ± 1.9%) and 0.3 ± 1.42 mm2 (0.4% ± 2.0%), respectively. The upper and lower limits of agreement between MRI and 3-DUS for volume, length and average CSA were -0.4 to 61.7 mm3 (-0.2% to 2.3%), -1.0 to 1.5 mm (-3.2% to 4.5%) and -2.5 to 3.1 mm2 (-3.5% to 4.3%), respectively. There were no significant differences between imaging methods in CSA along the length of the tendon. In conclusion, MRI and freehand 3-DUS may be considered equivalent methods for estimating shape and 3-D geometry of the free Achilles tendon. These findings, together with the practical benefits of being able to assess 3-D Achilles tendon shape and geometry in a laboratory environment and under isometric loading, make 3-DUS an attractive alternative to MRI for assessing 3-D free Achilles tendon macro-structure in future studies.

Thyroid Function Decline and Diet in Female High School Long-distance Runners.

We aimed to clarify the state of thyroid function in female high school long-distance runners. We evaluated the associations between thyroid function and menstrual condition, bone mineral density (BMD), nutritious status, and body composition. The subjects' height and weight were measured, along with fat percentage, fat mass, muscle mass, and BMD with dual-energy X-ray absorptiometry. A nutrition and dietary survey measured the subjects' intake of energy and nutrients based on meals provided at the subjects' dorm for 3 days in July of 2016 and 2017. Blood parameters including thyroid hormone and estradiol were measured. Most of the subjects (81.3%) were underweight (body mass index <18.5). The thyroid hormone free T3 value was decreased, but TSH was not increased and was similar to that observed in individuals with anorexia nervosa. In our subjects, thyroid hormone was associated with BMD and nutritional intake. To improve the menstruation abnormality of female athletes and to increase their bone density, the athletes' weight should be managed by proper nutrient intake and the maintenance of their thyroid function.

The effect of long-distance running on bone strength and bone biochemical markers.

It still remains controversial whether exercise will help or adversely affect the bone formation. The aim of this study was to evaluate the effect of common long-distance running on the magnitude of change in bone properties as measured by quantitative ultrasound (QUS) and bone biochemical markers. Subjects included 68 long-distance runners and 40 controls. Long-distance runners had been training in the marathon club for at least 6 months, the average period of exercise was 2 years, and running at 48.6±24.9 km per week. Otherwise, controls were people who had not experienced any specific sports before. Bone speed of sound (SOS) was measured by QUS at the distal one third radius and the mid-shaft of the tibia. Serum osteocalcin and urine deoxypyridinolin were measured in all groups. No significant differences were found in tibial and radial SOS between the two groups. Serum osteocalcin was higher in long-distance runners than control (P<0.05) in both the 30s and 40s of the participants, but urine deoxypyridinolin showed no significant difference between the two groups. It is concluded that long-distance running at the club level increases bone formation marker, but seems to do no harmful effect on bone properties as measured by QUS.

Foot strike pattern, step rate, and trunk posture combined gait modifications to reduce impact loading during running.

Elevated impact loading can be detrimental to runners as it has been linked to the increased risk of tibial stress fracture and plantar fasciitis. The objective of this study was to investigate the combined effects of foot strike pattern, step rate, and anterior trunk lean gait modifications on impact loading in runners. Nineteen healthy runners performed 12 separate gait modification trials involving: three foot strike patterns (rearfoot, midfoot, and forefoot strike), two step rates (natural and 10% increased), and two anterior trunk lean postures (natural and 10-degree increased flexion). Overall, forefoot strike combined with increased step rate led to the lowest impact loading rates, and rearfoot strike combined with anterior trunk lean led to the highest impact loading rates. In addition, there were interaction effects between foot strike pattern and step rate on awkwardness and effort, such that it was both more natural and easier to transition to a combined gait modification involving forefoot strike and increased step rate than to an isolated gait modification involving either forefoot strike or increased step rate. These findings could help to inform gait modifications for runners to reduce impact loading and associated injury risks.