Trained Distance Runners Research Articles

Inspiratory Muscle Warm-up Improves 3,200-m Running Performance in Distance Runners.

Barnes, KR and Ludge, AR. Inspiratory muscle warm-up improves 3,200-m running performance in distance runners. J Strength Cond Res 35(6): 1739-1747, 2021-This study examined the effects of an inspiratory muscle exercise as part of a warm-up (IMW) using a resisted breathing trainer on running performance. In a randomized crossover design, 17 trained distance runners completed two 3,200-m performance trials on separate days, preceded by 2 different warm-up procedures: IMW or sham IMW (CON). In each condition, subjects performed 30 breaths against either 50% of each athlete's peak strength (IMW) or 30 slow protracted breaths against negligible resistance (CON). Perceived race readiness and inspiratory muscle strength, flow, power, and volume were measured before and after each warm-up. Heart rate (HR), rating of perceived exertion (RPE) and dyspnea (RPD), and expired gases were collected during each trial. A 3,200-m run performance was 2.8% ± 1.5% (20.4-second) faster after IMW (effect size [ES] = 0.37, p = 0.02). After each warm-up condition, there was as small effect on peak inspiratory strength (6.6 ± 4.8%, ES = 0.22, p = 0.02), flow (5.2 ± 4.4%, ES = 0.20, p = 0.03), power (17.6 ± 16.7%, ES = 0.22, p = 0.04), and volume (6.7 ± 6.3%, ES = 0.24, p = 0.01) after IMW compared with CON. There were no differences in HR, minute volume, peak V̇o2, or V̇o2 at each 800-m interval between conditions (ES ≤ 0.13, p > 0.17). There were small differences in RPE at 800 m and 1,600 m (ES = 0.32, p = 0.17; ES = 0.21, p = 0.38, respectively), but no difference at the last 1,600 m (p = 1.0). There was a moderate positive effect on RPD (ES = 0.81, p < 0.001) and race readiness (ES = 0.76, p < 0.01) after IMW. Overall, the data suggest that IMW improves 3,200-m performance because of enhancements in inspiratory muscle function characteristics and reduction in dyspnea.

Focus of attention in trained distance runners

The superiority of using an external focus of attention for learning and performance benefits has been documented in distance running. However, there is limited research examining the actual attentional focus strategies adopted by distance runners. The purpose of this study was to describe the focus of attention used by distance runners in practice and competition and to better understand where these athletes seek information about improving performance. Sixteen distance runners (32.1 ± 10.0 yr) who run at least 20 mile/week (37.7 ± 10.8 mile/week) completed a questionnaire examining information related to attentional focus during training and competition and where athletes go for educational resources. Results indicate that distance runners do not solely adhere to external focus of attention, rather utilize multiple forms of attentional focus strategies that are not examined in laboratory research. Further, it seems that most training advice is received from coaches or training partners and not scientific literature.

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.

Effects Of High-fat Diet And Exercise On Total Plasma Macronutrient Contents By Fourier-transform Infrared Spectroscopy

High fat-low carbohydrate (HFLC) diets are increasingly considered by endurance athletes to enhance their performances and overall health. Total macronutrient contents in plasma may be affected by diets and exercise. PURPOSE: To examine the effects of HFLC diet and an acute bout of exercise on total plasma macronutrient contents in trained males. METHODS: Eight trained distance runners (age = 39.5±9.9 years and VO2max = 47.9±7.6 mL/kg/min) that were on high-carbohydrate (HC) diets adopted the HFLC diet for 3 weeks, which consisted of 70% of overall caloric intake from fats and no more than 50g of carbohydrates. At the end of each diet trial, participants performed an indoor treadmill exercise for 50 minutes at varying race paces followed by an outdoor 5-km time trial. Overnight fasting blood samples were collected at pre- (baseline) and post-exercise (24-hours) to analyze changes in total plasma lipids, proteins, and carbohydrates using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR FT-IR). The O-H stretch vibrational band of water was used to normalize the IR spectra and the protein content was quantified by measuring the amide I peak intensity at 1600 - 1700 cm-1. To quantify the lipids and carbohydrates, the samples were lyophilized and measured by the intensities at 2800 - 3000 cm-1 and 800 - 1200 cm-1, respectively. RESULTS: The ATR FT-IR analysis showed that total plasma proteins remained unchanged (HC baseline = 135.20±4.20 and HFLC baseline = 135.24±3.91AU). However, the HC diet at baseline showed a significant accumulation of lipids (30.06±7.75 AU, 95% CI = 6.93) and carbohydrates (42.92±11.62 AU, 95% CI = 10.39). Additionally, total lipids in the HC diet significantly decreased at 24-hours post-exercise (from 30.06±7.75 to 28.51±7.91 AU, p=0.016). CONCLUSION: A short-term high-fat diet does not significantly alter any macronutrient contents in plasma, whereas a high-carbohydrate diet increases an accumulation of lipids and carbohydrates. Elevated plasma lipids and carbohydrates with a high-carbohydrate diet may be due to decreased insulin sensitivity, which consequently led to increased plasma lipid contents. Notably, decreased total plasma lipid content following an acute bout of exercise suggests that lipids were the primary energy substrate.

Aging, Maximal Aerobic Capacity, and Running Economy in Trained Distance Runners

Aging, Maximal Aerobic Capacity, and Running Economy in Trained Distance Runners

Long Ground Contact Time Enhances Running Economy at High-Intensity Running

Running economy (RE) determines the difference in distance running performance in highly-trained runners. Studies have highlighted RE importance during high-intensity running. Although RE is related to ground contact time (Tc), the relationship between RE at high-intensity running and Tc is not elucidated. It is also unclear whether the hamstrings muscle, which contribute to high-intensity running, affect RE and Tc. PURPOSE: We aimed to clarify the relationships among RE, Tc at intensity below and above the lactate threshold (LT) run, and hamstring muscle’s cross-sectional area in highly-trained long-distance runners. METHODS: We enrolled 11 highly trained male distance runners (IAAF score: 1038 ± 48). They underwent treadmill running test to assess the LT, and RE. RE was evaluated at 270 (RE270) and 360 m/min (RE360) as the intensity below and above the LT, respectively. Tc was also valuated at the same velocity (Tc270; Tc360). Both medial and lateral hamstring muscles’ cross-sectional areas (MHA and LHA, respectively) were calculated using MRI at 50% position of the right thigh. RESULTS: The subjects’ LT, RE270 and RE360 were 337 ± 17 m/min, 0.90 ± 0.08 kcal/ kg/km, and 1.00 ± 0.07 kcal/kg/km, respectively. The Tc270, Tc360, MHA and LHA values were 195 ± 17 ms, 164 ± 9 ms, 1.24 ± 0.18 cm2/kg0.67, and 0.99 ± 0.11 cm2/kg0.67, respectively. RE270 showed a significant relationship with Tc270, MHA, and LHA (r = -0.81, 0.75, and 0.60, respectively; P < 0.05), but no relationship was noted with IAAF score (r = -0.55; P = 0.08). Tc270 was related to MHA and LHA (r = -0.63 and -0.67; P < 0.05). Although RE360 showed a significant relationship with IAAF score, Tc360, and MHA (r = -0.73, -0.65, and 0.69, respectively; P < 0.05), no relationship was noted with LHA (r = 0.35; P = 0.30). Tc360 did not exhibit any significant relationship with MHA (r = -0.55; P = 0.08) and LHA (r = -0.52; P = 0.10). CONCLUSION: The findings of this study are as follows: (a) RE at high rather than low intensity is related to running performance; (b) longer Tc enhances RE; (c) superior RE and long Tc at low intensity are related to small hamstring muscles, but these associations disappear, except between RE and MHA, at high intensity. These results suggest that long Tc at high-intensity contributes to superior RE, but not to hamstring muscles, and leads to higher running performance.

A Comparison of Two VO2max Treadmill CPETs in Highly Trained Distance Runners

Measuring maximal oxygen consumption (VO2max) via treadmill testing is a popular procedure for testing aerobic power and subsequently developing exercise prescriptions. Previous studies have produced conflicting results when comparing horizontal and incline graded treadmill protocols designed to assess VO2max, and the variability may be due to the heterogeneity of subjects, having different fitness levels and backgrounds. PURPOSE: To prospectively compare the VO2max value attained during a horizontal (increment in speed only) (SOVO2max) and an inclined (constant speed with increment in grade only) (GOVO2max) cardiorespiratory exercise tests (CPETs) in highly trained distance runners. A secondary purpose examined if the ventilatory threshold (VT) determined from the SOVO2max and GOVO2max CPETs occurred at the same percent of VO2max (% VO2max @ VT). METHODS: After a familiarization session performing the Bruce Protocol, VO2max and % VO2max @ VT were evaluated in 16 male distance runners, some who preferred hilly terrain and some who preferred flat or track running, using the SOVOmax and GOVOmax CPETs. Dependent samples t-tests were used to compare the VO2max and % VO2max @ VT results between the SOVO2max and GOVO2max CPETs. RESULTS: VO2max values were significantly higher from the GOVO2max in comparison to the SOVO2max protocol (76.1 and 71.2 mLO2/kg/min, p=. 005); however, the % VO2max @ VT was not significantly different between the GOVO2max and SOVO2max protocols (77.5% and 77.2%, p=.825). CONCLUSION: Higher VO2max values were attained on the GOVO2max CPET, even on those who reported they were track athletes and favored running on the flat surfaces. These results agree with previous research that found athletes who train and compete on an exclusively flat surface or hilly terrain both tend to produce higher VO2max values on CPETs that include changes in treadmill grade. However, due to the non-significant difference in % VO2max @ VT observed between the SOVO2max or GOVO2max CPETs, for the determination of training thresholds, runner specialty (flat versus hill runners) should therefore be considered when selecting the most appropriate CPET in this athletic population.

Does Stance Time Predict Running Economy at Relative Speeds in Highly Trained Distance Runners?

Running economy (RE) is an important component of distance running performance. Recent evidence suggests shorter stance times (ST) are related to superior RE and practitioners often recommend shorter ST for this benefit. However, overall, reports are equivocal, perhaps because comparisons are usually made at absolute running speeds, which fails to account for differences in relative fitness. To date, this relationship has not been explored at relative intensities. PURPOSE: To determine the relationship of ST and RE at absolute and relative running speeds. METHODS: 20 highly trained distance runners (13 M, 7 F; VO2max = 67.6 vs 53.5 ml/kg/min) consented to procedures approved by EMU-HSRC. Session 1 included a critical speed (CS) field test to determine relative fitness and establish relative testing speeds. Session 2 included two treadmill tests for kinematic and metabolic measurements. For both tests, subjects ran at 10, 12, 14, and 16 km/h (absolute speeds) and at 75, 85, and 95% CS (relative speeds). Kinematic data were collected for 60 sec using lower-body optical motion capture (Plug-In-Gait; Vicon, Centennial, CO). Metabolic data were collected using open circuit spirometry (TrueOne 2400, ParvoMedics, Sandy, UT) during three-minute trials, where the last 60 sec of each stage was used to calculate RE. Linear regressions were used to determine the relationship between ST and RE expressed as mL/kg/km, %VO2max, and kcal/kg/km, done separately for absolute and relative speeds. α was set at .05. RESULTS: For absolute speeds, significant negative relationships were found between ST and RE expressed as mL/kg/km (β = -.374), %VO2max (β = -.461), and kcal/kg/km (β = -.459) (all p < .01). For relative speeds, a significant negative relationship was found for RE expressed as %VO2max (β = -.318) (p < .05) but not mL/kg/km or kcal/kg/km (p > .05). CONCLUSION: Contrary to some reports and recommendations, for comparisons using absolute speeds, shorter ST was related to inferior RE. Comparisons using relative speeds showed weaker or non-significant relationships. Therefore, changes in RE mediated by ST may depend more on individual exercise strain than absolute speed. Future investigations should consider using relative intensities for a more appropriate comparison between individuals.

Correction: Pilates training improves 5-km run performance by changing metabolic cost and muscle activity in trained runners.

[This corrects the article DOI: 10.1371/journal.pone.0194057.].

The efficacy of downhill running as a method to enhance running economy in trained distance runners

Running downhill, in comparison to running on the flat, appears to involve an exaggerated stretch-shortening cycle (SSC) due to greater impact loads and higher vertical velocity on landing, whilst also incurring a lower metabolic cost. Therefore, downhill running could facilitate higher volumes of training at higher speeds whilst performing an exaggerated SSC, potentially inducing favourable adaptations in running mechanics and running economy (RE). This investigation assessed the efficacy of a supplementary 8-week programme of downhill running as a means of enhancing RE in well-trained distance runners. Nineteen athletes completed supplementary downhill (−5% gradient; n = 10) or flat (n = 9) run training twice a week for 8 weeks within their habitual training. Participants trained at a standardised intensity based on the velocity of lactate turnpoint (vLTP), with training volume increased incrementally between weeks. Changes in energy cost of running (EC) and vLTP were assessed on both flat and downhill gradients, in addition to maximal oxygen uptake (⩒O2max). No changes in EC were observed during flat running following downhill (1.22 ± 0.09 vs 1.20 ± 0.07 Kcal kg−1 km−1, P = .41) or flat run training (1.21 ± 0.13 vs 1.19 ± 0.12 Kcal kg−1 km−1). Moreover, no changes in EC during downhill running were observed in either condition (P > .23). vLTP increased following both downhill (16.5 ± 0.7 vs 16.9 ± 0.6 km h−1,P = .05) and flat run training (16.9 ± 0.7 vs 17.2 ± 1.0 km h−1, P = .05), though no differences in responses were observed between groups (P = .53). Therefore, a short programme of supplementary downhill run training does not appear to enhance RE in already well-trained individuals.

Pilates training improves 5-km run performance by changing metabolic cost and muscle activity in trained runners.

PurposeStrength training improves distance running economy and performance. This finding is based predominantly on maximal and explosive strength programmes applied to locomotor muscles, particularly on the lower limbs. It is not certain whether a minimization of metabolic cost (Cmet) and an improvement in running performance is feasible with strength training of the postural and trunk muscles.MethodsUsing kinematic, neuromuscular and metabolic measurements of running at two different speeds before and after a 12-week Pilates training programme, we tested the hypothesis that core training might improve the running Cmet and performance of trained runners. Thirty-two individuals were randomly assigned to the control group (CG, n = 16) or the Pilates group (PG, n = 16).ResultsConfirming our hypothesis, a significant improvement (p<0.05) was observed for running performance in the PG (pre: 25.65±0.4 min; post: 23.23±0.4 min) compared to the CG (pre: 25.33±0.58 min; post: 24.61±0.52 min). Similarly, the PG (4.33±0.07 J.kg-1.m-1) had better responses than the CG (4.71±0.11 J.kg-1.m-1) during post-training for Cmet. These findings were accompanied by decreased electromyographic activity of the postural muscles at submaximal running intensities in the PG.ConclusionsOverall, these results provide a rationale for selecting strength training strategies that target adaptations on specific postural and locomotor muscles for trained distance runners.

Locomotor-respiratory coupling is maintained in simulated moderate altitude in trained distance runners.

To determine whether acute exposure to simulated moderate altitude alters locomotor-respiratory coupling (LRC) patterns in runners, 13 trained male distance runners performed a running economy and maximal oxygen uptake (V̇o2max) test in normoxia (NORM) and hypoxia (HYP) ([Formula: see text]= 15.8%; ~2,400 m/8,000 ft) on separate days. Running economy (RE), the degree of LRC, stride frequency-to-breathing frequency quotients (SF/fb), ratings of perceived exertion (RPE), and dyspnea were assessed at three common submaximal speeds and V̇o2max. SF/fb were significantly lower at each submaximal speed in HYP (12.9 km/h: 2.91 ± 0.20 vs. 2.45 ± 0.17, 14.3 km/h: 2.53 ± 0.17 vs. 2.21 ± 0.14, 16.1 km/h: 2.22 ± 0.14 vs. 1.95 ± 0.09; P < 0.05). The degree of LRC (range: 36-99%) in HYP was not significantly different than NORM at any of the three common submaximal speeds. However, the degree of LRC was significantly higher at V̇o2max in HYP than NORM (43.8 ± 3.4% vs. 57.1 ± 3.8%; P < 0.05). RE and RPE were similar at all running speeds. Dyspnea was significantly greater in HYP compared with NORM at 16.1 km/h ( P < 0.05). Trained distance runners are able to maintain LRC in HYP, despite increases in breathing frequency. Within this unique population, years of training may enhance and optimize the ability to maintain LRC to minimize metabolic costs and dyspnea. NEW & NOTEWORTHY Exposure to acute altitude causes increases in ventilation at rest and any submaximal exercising workload, which may alter locomotor-respiratory coupling (LRC). Our data suggest that trained distance runners can maintain LRC during acute exposure to simulated moderate altitude, even when breathing frequency is increased at any submaximal pace.

Physiological and Biomechanical Responses of Highly Trained Distance Runners to Lower-Body Positive Pressure Treadmill Running

BackgroundAs a way to train at faster running speeds, add training volume, prevent injury, or rehabilitate after an injury, lower-body positive pressure treadmills (LBPPT) have become increasingly commonplace among athletes. However, there are conflicting evidence and a paucity of data describing the physiological and biomechanical responses to LBPPT running in highly trained or elite caliber runners at the running speeds they habitually train at, which are considerably faster than those of recreational runners. Furthermore, data is lacking regarding female runners’ responses to LBPPT running. Therefore, this study was designed to evaluate the physiological and biomechanical responses to LBPPT running in highly trained male and female distance runners.MethodsFifteen highly trained distance runners (seven male; eight female) completed a single running test composed of 4 × 9-min interval series at fixed percentages of body weight ranging from 0 to 30% body weight support (BWS) in 10% increments on LBPPT. The first interval was always conducted at 0% BWS; thereafter, intervals at 10, 20, and 30% BWS were conducted in random order. Each interval consisted of three stages of 3 min each, at velocities of 14.5, 16.1, and 17.7 km·h−1 for men and 12.9, 14.5, and 16.1 km·h−1 for women. Expired gases, ventilation, breathing frequency, heart rate (HR), rating of perceived exertion (RPE), and stride characteristics were measured during each running speed and BWS.ResultsMale and female runners had similar physiological and biomechanical responses to running on LBPPT. Increasing BWS increased stride length (p < 0.02) and flight duration (p < 0.01) and decreased stride rate (p < 0.01) and contact time (p < 0.01) in small-large magnitudes. There was a large attenuation of oxygen consumption (VO2) relative to BWS (p < 0.001), while there were trivial-moderate reductions in respiratory exchange ratio, minute ventilation, and respiratory frequency (p > 0.05), and small-large effects on HR and RPE (p < 0.01). There were trivial-small differences in VE, respiratory frequency, HR, and RPE for a given VO2 across various BWS (p > 0.05).ConclusionsThe results indicate the male and female distance runners have similar physiological and biomechanical responses to LBPPT running. Overall, the biomechanical changes during LBPPT running all contributed to less metabolic cost and corresponding physiological changes.

Locomotor-Respiratory Coupling is Maintained in Hypoxia in Trained Distance Runners

PURPOSE: To determine if acute exposure to normobaric hypoxia alters locomotor-respiratory coupling (LRC) patterns typically observed in trained runners, and to determine if any changes in LRC influence running economy (RE) and/or perceptions of ventilatory effort. METHODS: Trained male distance runners (n=13) with VO2max = 66.8 ± 1.1 ml kg-1 min-1 completed two laboratory visits, each in a different inspired gas condition, either normoxia (NORM) or hypoxia (HYP) (FIO2 = 15.8%; ~ 2500 m/8000ft). During each visit, subjects ran for 5 min at each of three constant submaximal speeds of 12.9, 14.3, and 16.1 km hr-1 with 4 min standing rest between speeds. Following the third stage, an incremental incline ramp protocol was used to determine VO2max. RE and LRC measures were taken during the 4th min of each speed (3:00–4:00), while ratings of perceived exertion (RPE) and dyspnea (DYS) were taken during the first 30 seconds of the final minute at each speed (4:00–4:30), and again at the conclusion of the test. The degree of LRC was calculated as the highest number of inspirations or expirations beginning in the same decile of the step divided by the total number of breaths. RESULTS: Compared with NORM, the degree of LRC was not significantly different at any of the three common submaximal speeds with exposure to HYP, however it was increased at VO2max (43.8 ± 3.4% vs. 57.1 ± 3.8%; p < 0.05). Breathing frequency (breaths min-1) was significantly increased at each submaximal speed in HYP compared to NORM (30.3 ± 1.9 vs. 35.9 ± 2.2, 34.8 ± 2.0 vs. 39.8 ± 2.2, 40.4 ± 2.4 45.2 ± 1.9; p < 0.05), but was not significantly different at VO2max. Stride frequency-to-breathing frequency quotients were significantly lower at each submaximal speed in HYP (2.91 ± 0.20 vs. 2.45 ± 0.17, 2.53 ± 0.17 vs. 2.21 ± 0.14, 2.22 ± 0.14 vs. 1.95 ± 0.09; p < 0.05) due to increases in breathing frequency while maintaining stride frequency. RE and RPE were not significantly different at any speed. DYS was only significantly different between NORM and HYP at 16.1 km hr-1 (p < 0.05). CONCLUSIONS: Trained distance runners are able to maintain LRC in hypoxia, even when breathing frequency is increased at any submaximal pace. It is possible that within this unique population, years of training enhance and optimize the ability to make adjustments to LRC in order to minimize metabolic costs.

Prevalence of Exercise-Induced Arterial Hypoxemia in Distance Runners at Sea Level.

It has been reported that ~50% of endurance-trained men demonstrate exercise-induced arterial hypoxemia (EIAH) during heavy exercise. However, this often-cited prevalence rate comes from a single study using a cohort of 25 highly trained men who completed maximal cycle ergometry. As arterial oxyhemoglobin saturation (SpO2) during maximal exercise is reported to be significantly lower during treadmill versus cycle ergometry in the same subjects, we hypothesized that the prevalence of EIAH would be greater than previously reported (and commonly referenced) in a larger cohort of highly endurance-trained men during maximal treadmill running. Data from 124 highly trained male distance runners (V˙O2max range = 60.3-84.7 mL·kg·min) were retrospectively examined from previously published studies completed in the Indiana University Human Performance Laboratory. Subjects completed a constant speed, progressive-grade treadmill exercise test to volitional exhaustion, and arterial oxyhemoglobin saturation (SaO2ear) in all subjects was estimated using the same oximeter (Hewlett Packard 47201A). Using similar inclusion criteria as previously published for highly trained (V˙O2max > 68 mL·kg·min) and for EIAH (SaO2ear ≤ 91%), 55 of 79 subjects (70%) exhibited exercise-induced arterial desaturation. Across all 124 subjects, 104 (84%) demonstrated at least moderate EIAH (SaO2ear ≤ 93%) during maximal treadmill exercise. SaO2ear was significantly yet weakly correlated with V˙E/V˙O2 (P < 0.01, r = 0.28) and V˙E/V˙CO2 (P < 0.001, r = 0.33) but not with V˙O2max. These results indicate that the prevalence of EIAH in highly trained men during maximal treadmill exercise at sea level is greater compared with previously suggested data, with exercise mode perhaps playing a factor in the number of athletes who experience EIAH.

Association of Body Composition with the Performance Level and Running Mileage among Long Distance Runners

PURPOSE: To assess the association between leanness and running performance and training volume among highly trained Japanese long distance runners. METHODS: Body composition was measured by dual energy X-ray absorptiometry in 54 Japanese male long distance runners who belonged to a university track and field team (19.8±1.3 yrs). The training volume was assessed by the average running mileage (km/month) during 5 months prior to the measurement. The runners were routinely divided into 4 categories by the coach of the team according to their performance level and the category of the period was used as the performance level of the runners; team A (n=15), B (n=17), C (n=11), and D (n=11) in the order of the level. Team D included runners who had injuries and restricted their training. Questionnaire survey was performed regarding weight control practices and complaints of fatigue. Written informed consent was obtained from each runner. RESULTS: The mean running mileage of the 54 runners was 606 km/month. Height, body mass, BMI, percent body fat, bone mineral density (BMD), z-score of BMD, and lean soft tissue mass were 172.0±5.2 cm, 57.3±4.4 kg, 19.4±1.0 kg/m2, 6.1±1.3%, 1.175±0.057 g/cm2, -0.524±0.677, and 51.1±4.0 kg, respectively. The mean running mileage was not significantly correlated with any of those variables (p>0.05). The mean running mileage of each category (A, B, C, & D) were 709, 600, 606, and 475 km/month, respectively (p<0.01). Percent body fat were lowest in A (5.7%) and highest in D (6.4%) whereas z-score of BMD were -0.447 and -0.664, respectively. However, ANOVA showed no significant differences in those variables among the categories. Fisher’s exact tests of questionnaire survey revealed significant between-categories differences in percentages of runners attempting weight reduction practices (8.3, 13.3, 53.8, and 38.5%, respectively, p<0.05) and those complained of frequent fatigue (25.0, 53.3, 53.8, and 69.2%, respectively, p<0.05). CONCLUSIONS: The runners had exclusively lean bodies regardless of their performance level and running mileage. The runners with the lowest performance level and the least training volume likely attempted weight reduction practice and complained of fatigue. It was concerned that they might pursue the lower level of percent body fat by restricting energy intake.

Continuous three dimensional analysis of running mechanics during a marathon by means of inertial magnetic measurement units to objectify changes in running mechanics

Recent developments in wearable and wireless sensor technology allow for a continuous three dimensional analysis of running mechanics in the sport specific setting. The present study is the first to demonstrate the possibility of analyzing three dimensional (3D) running mechanics continuously, by means of inertial magnetic measurement units, to objectify changes in mechanics over the course of a marathon.Three well trained male distance runners ran a marathon while equipped with inertial magnetic measurement units on trunk, pelvis, upper legs, lower legs and feet to obtain a 3D view of running mechanics and to asses changes in running mechanics over the course of a marathon. Data were continuously recorded during the entire 42.2km (26.2Miles) of the Marathon. Data from the individual sensors were transmitted wirelessly to a receiver, mounted on the handlebar of an accompanying cyclist. Anatomical calibration was performed using both static and dynamic procedures and sensor orientations were thus converted to body segment orientations by means of transformation matrices obtained from the segment calibration. Joint angle (hip, knee and ankle) trajectories as well as center of mass (COM) trajectory and acceleration were derived from the sensor data after segment calibration.Data were collected and repeated measures one way ANOVA׳s, with Tukey post-hoc test, were used to statistically analyze differences between the defined kinematic parameters (max hip angle, peak knee flexion at mid-stance and at mid-swing, ankle angle at initial contact and COM vertical displacement and acceleration), averaged over 100 strides, between the first and the last stages (8 and 40km) of the marathon. Significant changes in running mechanics were witnessed between the first and the last stage of the marathon.This study showed the possibility of performing a 3D kinematic analysis of the running technique, in the sport specific setting, by using inertial magnetic measurement units. For the three runners analyzed, significant changes were observed in running mechanics over the course of a marathon. The present measurement technique therefore allows for more in-depth study of running mechanics outside the laboratory setting.

The effects of a systematic increase in relative humidity on thermoregulatory and circulatory responses during prolonged running exercise in the heat

ABSTRACTThis study examined the thermoregulatory and circulatory responses, and exercise performance of trained distance runners during exercise in the heat (31°C) at varying relative humidity (RH). In a randomized order, 11 trained male distance runners performed 5 60 min steady-state runs at a speed eliciting 70% of VO2max in RH of 23, 43, 52, 61 and 71%. This was followed immediately with an incremental exercise test to volitional exhaustion. Core (Tre) and mean skin temperature (T¯sk), cardiac output (Q), heart rate (HR), and stroke volume (SV) were recorded at regular intervals. A significant (P = 0.003) main effect was detected for RH on mean body temperature (Tb), with a significantly higher Tb detected during steady-state exercise in the 61 and 71% RH compared to that in the 23% RH. During the steady-state exercise, no differences were detected in whole body sweat loss (P = 0.183). However, a significant main effect of RH was observed for HR and SV (P = 0.001 and 0.006, respectively) but not Q (P = 0.156). The time to exhaustion of the incremental exercise test was significantly reduced at 61 and 71% RH compared with 23% RH (P = 0.045 and 0.005, respectively). Despite an increase in dry heat loss, a greater thermoregulatory and circulatory stress was evident during steady-state exercise at 61 and 71% RH. This ultimately limits the capacity to perform the subsequent incremental exercise to exhaustion. This study highlighted that in a warm environment, the range of the prescriptive zone progressively narrows as RH increases.

Are the knee and ankle angles at contact related to the tendon properties of lower limbs in long distance runners?

The purpose of this study was to investigate whether the knee and ankle angles at contact during running were related to the elastic properties of tendon structures in knee extensors and plantar flexors and performance in trained long distance runners. Thirty-two highly trained male long distance runners participated in this study. Elongation of tendon structures in knee extensors and plantar flexors were measured using ultrasonography while subjects performed ramp isometric contractions up to the voluntary maximum. The relationship between estimated muscle force and tendon elongation was fit to a linear regression, the slope of which was defined as the stiffness of tendon structures. Knee and ankle angles at contact during running were determined at a speed of 18 km/h on a treadmill. Knee and ankle angles at contact were not correlated to the stiffness of tendon structures in knee extensors and plantar flexors. In addition, the best official record in a 5000-m race was not significantly correlated to knee and ankle joint angles at contact. In conclusion, knee and ankle angles at contact were not related to the elastic properties of tendon structures in knee extensors and plantar flexor and the performance of long distance running.

Effects of a minimalist shoe on running economy and 5-km running performance

ABSTRACTThe purpose of this study was to determine if minimalist shoes improve time trial performance of trained distance runners and if changes in running economy, shoe mass, stride length, stride rate and footfall pattern were related to any difference in performance. Twenty-six trained runners performed three 6-min sub-maximal treadmill runs at 11, 13 and 15 km·h−1 in minimalist and conventional shoes while running economy, stride length, stride rate and footfall pattern were assessed. They then performed a 5-km time trial. In the minimalist shoe, runners completed the trial in less time (effect size 0.20 ± 0.12), were more economical during sub-maximal running (effect size 0.33 ± 0.14) and decreased stride length (effect size 0.22 ± 0.10) and increased stride rate (effect size 0.22 ± 0.11). All but one runner ran with a rearfoot footfall in the minimalist shoe. Improvements in time trial performance were associated with improvements in running economy at 15 km·h−1 (r = 0.58), with 79% of the improved economy accounted for by reduced shoe mass (P < 0.05). The results suggest that running in minimalist shoes improves running economy and 5-km running performance.