Variability of competitive performance of distance runners

Acute effect of scapular mobilization with associated myofascial release on butterfly performance: Randomized clinical trial

INTRODUCTION

To evaluate the acute effect of scapular mobilization with associated myofascial release compared to scapular mobilization without myofascial release on butterfly stroke sports performance.

DESIGN

Randomized clinical trial.

METHOD

Pilot study that non-probabilistically convenience sampling that selected butterfly swimmers who were simply randomized into three groups to receive the standard protocol (scapular mobilization with release of the subscapularis muscle by the lateral edge of the scapula and rib cage detachment) in intervention group (IG), sham group (SG) (scapular mobilization without subscapularis muscle release and without rib cage detachment) or no intervention in control group (CG). We evaluated the stroke frequency, length, and average speed of 30 swimmers using the 8.15 Kinovea® motion analysis system.

RESULTS

The findings showed that, compared to the CG and IG, the SG showed a significant reduction in mean velocity (p = 0.002; p = 0.02, respectively), stroke frequency (p = 0.002; p = 0.003, respectively), and stroke length (p = 0.01; p = 0.05, respectively).

DISCUSSION

The results showed that manual therapy through scapular mobilization without associated myofascial release with detachment of the scapula from the rib cage worsened the swimming efficiency indicators even after 30 min of application of the technique. The limitations of the studies are related to the sample size, the risk of non-probabilistic contraction bias and the lack of blinding of the evaluators. Thus, the results of this study should be evaluated with caution.

An analysis of the São Silvestre race between 2007-2021: An increase in participation but a decrease in performance

This study aimed to investigate the trends of finishers in the São Silvestre race in Brazil, taking into account sex, age, and performance levels. A total of 31 ​775 runners (women, n ​= ​13 ​847; men, n ​= ​17 ​928), aged (45.2 ​± ​16.8) years, finishers in the São Silvestre race between 2007 and 2021, were considered in the present analysis. Data (event year, date of birth, sex, and race times) were downloaded from the official race website. The man-Whitney U test, Spearman correlation, and robust regression model were computed. Participation increased over time for both sexes. Regarding age groups, "31-40 years" (women) and "> 60 years" (men) were those with the highest number of finishers. We found a decrease in performance across the years (β ​= ​2.45; p ​< ​0.005), as well as significant differences in race times for both sexes (U ​= ​42.844; p ​< ​0.001), with men presenting better performances than women. Over time, it was observed an increase in the performance gap between the sexes, but in general, the performance decreased (β ​= ​1.76; p ​< ​0.001). Stakeholders should consider improving the strategies to improve women and young people's participation in running events.

Strength Assessment of Trunk Rotator Muscles: A Multicenter Reliability Study

BACKGROUND

Trunk rotator strength plays an important role in sports performance and health. A reliable method to assess these muscles with functional electromechanical dynamometer has not been described. Therefore, the objectives of this paper were (I) to explore the reliability of different strength variables collected in isokinetic and isometric conditions during two trunk rotator exercises, and (II) to determine the relationship of isometric and dynamic strength variables collected in the same exercise.

METHODS

A repeated measures design was performed to evaluate the reliability of the horizontal cable woodchop (HCW) and low cable woodchop (LCW) exercises. Reliability was assessed using t-tests of paired samples for the effect size, the standard error of measurement, the coefficient of variation (CV) and the intraclass correlation coefficient (ICC). The Pearson's (r) correlation coefficient was used to explore the association between isometric and isokinetic tests.

RESULTS

HCW exercise is more reliable than LCW exercise in assessing trunk rotator muscles. The strength manifestation that should be used is the average strength, and the most reliable evaluation was the HCW at 0.40 m·s-1 concentric (ICC = 0.89; CV = 10.21%) and eccentric (ICC = 0.85; CV = 9.33%) contraction and the dynamic condition that most correlated with the isometric was LWC at 0.50 m·s-1 (r = 0.83; p < 0.01).

CONCLUSION

HCW is a reliable exercise to measure trunk rotator muscles.

Olympic cycle periodicity in women's long and triple jumping performance between 1996 and 2019

Performance variability is present in a series of competition results in athletics. Some of the variability is random and some can be attributed to factors such as the environment and changes in the level of physical, mental, and technical states of the athlete. Changes in the state of the athlete may be due to the competition schedule. It has been shown that there is periodicity in performance aligned with the seasonal competition schedule in athletics and with the Olympic cycle in pooled athletics data dating from 1896 to 2008. We investigated whether Olympic cycle periodicity was present in modern era long and triple jumping in elite men and women. Top 50 performances per year in the horizontal jumps in men and women from 1996 to 2019 were used. Each performance was normalized to the best result from the previous Olympic year. Two-way ANOVAs revealed significantly lower mean normalized performances in top ten women compared to top ten men (p < 0.001) in both jumps. In both jumps, ten top-performing women also showed decreases between the Olympic year mean normalized performances and the 1st year following (Long Jump: p = 0.022, Triple Jump: p = 0.008). In triple jump, the decrease in performance was also found in the second year following the Olympics. Performances deciles ranked from 11th to 50th place showed a similar pattern in women's triple jump but only for ranks 11 to 20 in the women's long jump. The findings suggest that periodicity driven by the Olympic cycle exists in women's long and triple jump at the elite level.

Participation and performance characteristics in half-marathon run: a brief narrative review

Half-marathon (HM) is a running sport of increasing popularity in both sexes and in all age groups worldwide during the last years. Many studies have examined several aspects of HM, such as performance and participation trends, sex and age differences, physiological correlates, and training; however, no comprehensive review has ever been contacted to summarize the recently accumulated knowledge. Therefore, the aim of the present study was to review all previous research in this sport, focusing on participation and performance aspects. It was shown that HM runners had similar anthropometric and physiological characteristics as full-marathon runners which should be attributed to the affinity of these two races in terms of metabolic demands. Performance in HM was related with superior scores in aerobic capacity (maximal oxygen uptake, anaerobic threshold and running economy) and training characteristics (sport experience, weekly distance, training speed, frequency of sessions and long single endurance run distance), and lower scores in adiposity-related scores (e.g. body mass, body mass index, body fat percentage and skinfold thickness). Considering the popularity of HM race and the lack of many original studies (compared to FM race), this is an exciting field for scientific research with a large potential for practical applications, since the majority of HM runners are amateur runners in need of sex-, age- and performance-tailored exercise prescription.

Impact of advanced footwear technology on elite men's in the evolution of road race performance

Advanced footwear technology (AFT) changed footwear design concepts by using a curved carbon fibre plate in combination with new, more compliant and resilient foams. The aim of this study was (1) to examine the individual effects of AFT on the evolution of the main road events and (2) to re-assess the impact of AFT on the world's top-100 performance in men's 10k, half-marathon and marathon events. Data from the top-100 men's 10k, half-marathon and marathon performances were collected between 2015 and 2019. The shoes used by the athletes were identified in 93.1% of the cases by publicly available photographs. Runners wearing AFT had an average performance of 1671 ± 22.28 s compared to 1685 ± 18.97 s of runners not using AFT in 10k (0.83%) (p < 0.001), 3589 ± 29.79 s compared to 3607 ± 30.49 s in half-marathon (0.50%) (p < 0.001) and 7563 ± 86.10 s compared to 7637 ± 72.51 s in the marathon (0.97%) (p < 0.001). Runners wearing AFTs were faster by ~1% in the main road events compared to non-users. Individual analysis showed that ~25% of the runners did not benefit from the use of this type of footwear. The results of this study suggest that AFT has a clear positive impact on running performance in main road events.

Small changes in thermal conditions hinder marathon running performance in the tropics

We examined marathon performance of the same group of runners in relation to small changes in dry bulb temperature (T_db) and wet bulb temperature (T_wb) across 3 consecutive y, and investigated whether performance was poorer during an evening marathon compared with morning marathons. Marathon results were obtained from the 2017, 2018, and 2019 Standard Chartered Singapore Marathons. T_db, T_wb, T_d, relative humidity, and absolute humidity were gathered for each marathon. K-means clustering and linear regressions were performed on 610 runners who participated in all three marathons. Analysis of the 610 runners’ marathon performance was contrasted with T_db and T_wb. Linear regressions were also performed on 190 runners filtered by percentile, yielding similar results. For clusters with similar T_db from all runners K-means clustering, an increase in mean T_wb by 1.5°C coincided with an increase in finishing time by 559 s (9.3 min) (p < 0.033). T_wb hinders marathon performance more than T_db, with each percentage rise in T_db and T_wb resulting in an increase in net time by 7.6% and 39.1%, respectively (p < 0.025). Male and female runners’ response to T_db and T_wb changes were similar (overlap in 95% confidence intervals for the respective regression coefficients). In conclusion, small variations in environmental parameters affected marathon performance, with T_wb impairing marathon performance more than T_db. Marathon performance was likely better in the morning than evening, possibly due to time of day differences, along with unfavorable T_db that superseded training effects and the effects of lower T_wb.

The reproducibility of 20-min time-trial performance on a virtual cycling platform

This study aimed to analyse the reproducibility of mean power output during 20-min cycling time-trials, in a remote home-based setting, using the virtual-reality cycling software, Zwift. Forty-four cyclists (11 women, 33 men; 37 ± 8 years old, 180 ± 8 cm, 80.1 ± 13.2 kg) performed 3 x 20-min time-trials on Zwift, using their own setup. Intra-class correlation coefficient (ICC), coefficient of variation (CV) and typical error (TE) were calculated for the overall sample, split into 4 performance groups based on mean relative power output (25% quartiles) and sex. Mean ICC, TE and CV of mean power output between time-trials were 0.97 [0.95-0.98], 9.36 W [8.02-11.28 W], and 3.7% [3.2-4.5], respectively. Women and men had similar outcomes (ICC: 0.96 [0.89-0.99] vs 0.96 [0.92-0.98]; TE: 8.30 W [6.25-13.10] vs. 9.72 W [8.20-12.23]; CV: 3.8% [2.9-6.1] vs. 3.7% [3.1-4.7], respectively), although cyclists from the first quartile showed a lower CV in comparison to the overall sample (Q1: 2.6% [1.9-4.1] vs. overall: 3.7% [3.2-4.5]). Our results indicate that power output during 20-minute cycling time-trials on Zwift are reproducible and provide sports scientists, coaches and athletes, benchmark values for future interventions in a virtual-reality environment.

Highly Cushioned Shoes Improve Running Performance in Both the Absence and Presence of Muscle Damage

PURPOSE

We tested the hypotheses that a highly cushioned running shoe (HCS) would: 1) improve incremental exercise performance and reduce the oxygen cost (Oc) of submaximal running; and 2) attenuate the deterioration in Oc elicited by muscle damage consequent to a downhill run.

METHODS

Thirty-two recreationally-active participants completed an incremental treadmill test in a HCS and a control running shoe (CON) for the determination of Oc and maximal performance. Subsequently, participants were pair-matched and randomly assigned to one of the two footwear conditions to perform a moderate-intensity running bout pre- and 48 h post a 30-min downhill run designed to elicit muscle damage.

RESULTS

Incremental treadmill test performance was improved (+5.7%; +1:16 min:ss; P < 0.01) in the HCS when assessed in the non-damaged state, relative to CON. This coincided with a significantly lower Oc (-3.2%; -6 ml·kg-1·km-1; P < 0.001) at a range of running speeds and an increase in the speed corresponding to 3 mM blood lactate (+3.2%; +0.4 km·h-1; P < 0.05). As anticipated, the downhill run resulted in significant changes in biochemical, histological, and perceptual markers of muscle damage, and a significant increase in Oc (+5.2%; 10.1 ml·kg-1·km-1) was observed 48 h post. In the presence of muscle damage, Oc was significantly lower in HCS (-4.6%; -10 ml·kg-1·km-1) compared to CON.

CONCLUSIONS

These results indicate that HCS improved incremental exercise performance and Oc in the absence of muscle damage and show, for the first time, that despite worsening of Oc consequent to muscle damage, improved Oc in HCS is maintained.

Effect of concurrent strength and endurance training on run performance and biomechanics: A randomized controlled trial

This parallel-group randomized controlled trial investigated the effect of concurrent strength and endurance (CSE) training on running performance, biomechanics, and muscle activity during overground running. Thirty moderately trained distance runners were randomly assigned to 10-week CSE training (n = 15; 33.1 ± 7.5 years) or a control group (n = 15; 34.2 ± 8.2 years). Participants ran ≥30 km per week and had no experience with strength training. The primary outcome measure was 2-km run time. Secondary outcome measures included lower limb sagittal plane biomechanics and muscle activity during running (3.89 m s^-1 and maximal sprinting); maximal aerobic capacity (V̇O₂ max); running economy; and body composition. CSE training improved 2-km run time (mean difference (MD): -11.3 s [95% CI -3.7, -19.0]; p = 0.006) and time to exhaustion during the V̇O₂ max running test (MD 59.1 s [95% CI 8.58, 109.62]; p = 0.024). The CSE training group also reduced total body fat (MD: -1.05 kg [95% CI -0.21, -1.88]; p = 0.016) while total body mass and lean body mass were unchanged. Hip joint angular velocity during the early swing phase of running at 3.89 m s^-1 was the only biomechanical or muscle activity variable that significantly changed following CSE training. CSE training is beneficial for running performance, but changes in running biomechanics and muscle activity may not be contributing factors to the performance improvement. Future research should consider other possible mechanisms and the effect of CSE training on biomechanics and muscle activity during prolonged running under fatigued conditions.

Development and Validation of Prediction Equation of "Athens Authentic Marathon" Men's Race Speed

Aim

Despite the increasing popularity of outdoor endurance running races of different distances, little information exists about the role of training and physiological characteristics of recreational runners. The aim of the present study was (a) to examine the role of training and physiological characteristics on the performance of recreational marathon runners and (b) to develop a prediction equation of men’s race time in the “Athens Authentic Marathon.”

Methods

Recreational male marathon runners (n = 130, age 44.1 ± 8.6 years)—who finished the “Athens Authentic Marathon” 2017—performed a series of anthropometry and physical fitness tests including body mass index (BMI), body fat percentage (BF), maximal oxygen uptake (VO₂max), anaerobic power, squat, and countermovement jump. The variation of these characteristics was examined by quintiles (i.e., five groups consisting of 26 participants in each) of the race speed. An experimental group (EXP, n = 65) was used to develop a prediction equation of the race time, which was verified in a control group (CON, n = 65).

Results

In the overall sample, a one-way ANOVA showed a main effect of quintiles on race speed on weekly training days and distance, age, body weight, BMI, BF, and VO₂max (p ≤ 0.003, η² ≥ 0.121), where the faster groups outscored the slower groups. Running speed during the race correlated moderately with age (r = −0.36, p < 0.001) and largely with the number of weekly training days (r = 0.52, p < 0.001) and weekly running distance (r = 0.58, p < 0.001), but not with the number of previously finished marathons (r = 0.08, p = 0.369). With regard to physiological characteristics, running speed correlated largely with body mass (r = −0.52, p < 0.001), BMI (r = −0.60, p < 0.001), BF (r = −0.65, p < 0.001), VO₂max (r = 0.67, p < 0.001), moderately with isometric muscle strength (r = 0.42, p < 0.001), and small with anaerobic muscle power (r = 0.20, p = 0.021). In EXP, race speed could be predicted (R² = 0.61, standard error of the estimate = 1.19) using the formula “8.804 + 0.111 × VO₂max + 0.029 × weekly training distance in km −0.218 × BMI.” Applying this equation in CON, no bias was observed (difference between observed and predicted value 0.12 ± 1.09 km/h, 95% confidence intervals −0.15, 0.40, p = 0.122).

Conclusion

These findings highlighted the role of aerobic capacity, training, and body mass status for the performance of recreational male runners in a marathon race. The findings would be of great practical importance for coaches and trainers to predict the average marathon race time in a specific group of runners.

Face Cooling During Swimming Training in Tropical Condition

The aim of this study was to test the effect of face cooling with cold water (1.2 ± 0.7^°C) vs. face cooling with neutral water (28.0 ± 3.0^°C) during high-intensity swimming training on both the core temperature (T_co) and thermal perceptions in internationally ranked long-distance swimmers (5 men’s and 3 women’s) during 2 randomized swimming sessions. After a standardized warm-up of 1,200 m, the athletes performed a standardized training session that consisted of 2,000 m (5 × 400 m; start every 5’15”) at a best velocity then 600 m of aerobic work. Heart rate (HR) was continuously monitored during 5 × 400 m, whereas T_co, thermal comfort (TC), and thermal sensation (TS) were measured before and after each 400 m. Before and after each 400 m, the swimmers were asked to flow 200 mL of cold water (1.2^°C) or neutral (22^°C) water packaged in standardized bottles on their face. The swimmers were asked don’t drink during exercise. The velocity was significantly different between cold water and neutral water (p < 0.004 – 71.58 m.min^–1 ± 2.32 and 70.52 m.min^–1 ± 1.73, respectively). The T_co was increased by ±0.5^°C at race pace, under both face cooling conditions with no significant difference. No significant changes were noted in mean HR (i.e., 115 ± 9 and 114 ± 15 bpm for NW and CW, respectively). TC was higher with Cold Cooling than Neutral Cooling and TS was lower with Cold cooling compared with Neutral cooling. The changes in perceptual parameters caused by face cooling with cold water reflect the psychological impact on the physical parameters. The mean velocity was less important with face cooling whereas the heat rate and T_co were the same in the both conditions. The mechanism leading to these results seems to involve brain integration of signals from physiological and psychological sources.

Test-Retest Reliability of Plantar Flexion Torque Generation During a Functional Knee Extended Position in Older and Younger Men

Measuring ankle torque is of paramount importance. This study compared the test-retest reliability of the plantar flexion torque-generating capacity between older and younger men. Twenty-one older (68 ± 6 years) and 22 younger (25 ± 5 years) men were tested twice for maximal isometric plantar flexion. Peak torque (PT), rate of torque development, and contractile impulses (CI) were obtained from 0 to 50 ms (rate of torque development0-50; CI0-50) and from 100 to 200 ms (rate of torque development100-200; CI100-200). Typical error as the coefficient of variation (CVTE) and intraclass correlation coefficient were used to assess test-retest reliability. Student's t test was applied to investigate systematic errors. The CVTE ratio was used for between-group comparisons. Only PT demonstrated acceptable reliability (intraclass correlation coefficient ≥ .75 and CV ≤ 10%). Older men demonstrated greater CVTE than younger men for PT (ratio = 2.24), but lesser for rapid torque (ratio ≤ 0.84). Younger men demonstrated systematic error for PT (6.5%) and CI100-200 (-8.9%). In conclusion, older men demonstrated greater variability for maximal torque output, but lesser for rapid torque.

No Benefit of Ingestion of a Ketone Monoester Supplement on 10-km Running Performance

PURPOSE

Preexercise ingestion of exogenous ketones alters the metabolic response to exercise, but effects on exercise performance have been equivocal.

METHODS

On two occasions in a double-blind, randomized crossover design, eight endurance-trained runners performed 1 h of submaximal exercise at approximately 65% V˙O2max immediately followed by a 10-km self-paced time trial (TT) on a motorized treadmill. An 8% carbohydrate-electrolyte solution was consumed before and during exercise, either alone (CHO + PLA), or with 573 mg·kg of a ketone monoester supplement (CHO + KME). Expired air, HR, and RPE were monitored during submaximal exercise. Serial venous blood samples were assayed for plasma glucose, lactate, and β-hydroxybutyrate concentrations.

RESULTS

CHO + KME produced plasma β-hydroxybutyrate concentrations of approximately 1.0 to 1.3 mM during exercise (P < 0.001), but plasma glucose and lactate concentrations were similar during exercise in both trials. V˙O2, running economy, respiratory exchange ratio, HR, and RPE were also similar between trials. Performance in the 10-km TT was not different (P = 0.483) between CHO + KME (mean, 2402 s; 95% confidence interval, 2204-2600 s) and CHO + PLA (mean, 2422 s; 95% confidence interval, 2217-2628 s). Cognitive performance, measured by reaction time and a multitasking test, did not differ between trials.

CONCLUSIONS

Compared with carbohydrate alone, coingestion of KME by endurance-trained athletes elevated plasma β-hydroxybutyrate concentrations, but did not improve 10-km running TT or cognitive performance.

Are experienced and high-level race walking athletes able to match pre-programmed with executed pacing?

The objective of this study was to verify the agreement between pre-programmed and executed pacing during race walking and whether level of the athletes experience and performance influenced this relationship. Twenty-nine national and international race walkers participated in this study (14 males, 24.0±7.1 years old, and 15 females, 23.3±7.3 years old). Pre-programmed pacing for 10- and 20-km official walking races was self-selected via demonstrative pacing charts prior to races, while executed pacing was analyzed by a specialist investigator via an individual plot of current velocity versus distance. There was no agreement between pre-programmed and executed pacing (P=0.674). There was no association between the ability to match the pre-programmed pace with the executed pace and race walking experience or level of performance. Low- and high-performance athletes pre-programmed a similar pacing profile (P=0.635); however, high-performance athletes generally executed an even pacing strategy, while low-performance athletes generally adopted a positive pacing strategy (P=0.013). Race walkers did not faithfully match their pre-programmed with their executed pacing, and this seemed to be independent of previous experience and level of performance. High-performance athletes, however, tended to execute an even pacing strategy, even though this had not been pre-programmed.

Adipose Lipolysis Unchanged by Preexercise Carbohydrate Regardless of Glycemic Index

PURPOSE

This study aimed to determine the effect of preexercise carbohydrate of different glycemic indices on subcutaneous abdominal adipose tissue (SCAAT) metabolism and running performance.

METHODS

Ten trained male runners completed three experimental trials consisting of 30 min at 60% maximal oxygen consumption, 30 min at 75% maximal oxygen consumption, and a 5-km time trial. Thirty minutes before exercise, participants consumed one of three beverages: 1) 75 g low glycemic index modified starch supplement (UCAN), 2) 75 g high glycemic index glucose-based supplement (G), or 3) a flavor-matched noncaloric placebo (PL). SCAAT lipolysis was assessed via microdialysis.

RESULTS

Before exercise, blood glucose and insulin were elevated with G versus PL (+53.0 ± 21.3 mg·dL (mean ± SD), P < 0.0001; +33.9 ± 11.0 μU·mL, P < 0.0001) and G versus UCAN (+36.6 ± 24.9 mg·dL, P < 0.0001; +25.2 ± 11.0 μU·mL, P < 0.0001), respectively. Fat oxidation was attenuated, and carbohydrate oxidation increased before exercise with G versus PL (-0.06 ± 0.06 g·min, P = 0.005; +0.18 ± 0.07 g·min, P < 0.0001) and G versus UCAN (-0.06 ± 0.05 g·min, P = 0.004; +0.18 ± 0.14 g·min, P < 0.0001). However, there were no differences in SCAAT lipolysis at rest or during running at either exercise intensity. Also, there was no effect of treatment on running performance.

CONCLUSIONS

Preexercise carbohydrate lowers fat oxidation and increases carbohydrate oxidation, and these effects are attenuated with low glycemic index carbohydrate. However, these changes are not the result of alterations in SCAAT lipolysis, nor do they affect running performance.

Anticipated Task Difficulty Provokes Pace Conservation and Slower Running Performance

PURPOSE

Models of self-paced endurance performance suggest that accurate knowledge of the exercise end-point influences pace-related decision making. No studies have examined the effects of anticipated task difficulty during equidistant endurance activities. Accordingly, the purpose of this study was to investigate the effects of anticipated task difficulty on pacing, psychological, and physiological responses during running time trials.

METHODS

Twenty-eight trained runners completed three self-paced 3000-m time trials. The first was a baseline time trial completed on a 0% treadmill gradient. Time trials 2 and 3 were counterbalanced. Before a known incline time trial, anticipated to be more difficult, subjects were accurately informed that the gradient would increase to 7% for the final 800 m. Before an equivalent, unknown incline (UI) time trial subjects were deceptively informed that the gradient would remain at 0% throughout.

RESULTS

Expressed relative to baseline, running speed was 2.44% slower (d = -0.47) over the first 2200 m during known incline (KI) time trial than UI time trial. Effort perception, affective valence, heart rate, and blood lactate did not differ between time trials. Initial running speed during KI was related to pretrial motivation, pretrial vigor, perceived effort, and affective valence (all r ≥ 0.382). No such relationships existed during UI. More subjects also reported a conscious focus on pacing during KI.

CONCLUSIONS

An anticipated increase in task difficulty provoked pace conservation during 3000 m running time trials. The reduced pace may have resulted from greater task uncertainty and consciously aware, effort- and affect-based decisions to conserve energy and maintain hedonic state during KI. The findings add to theoretical understandings of factors that influence pacing during endurance activity. Consequently, recommendations to minimize the potentially deleterious effects of anticipated increases in task difficulty are provided.

Modelling of Running Performances: Comparisons of Power-Law, Hyperbolic, Logarithmic, and Exponential Models in Elite Endurance Runners

Many empirical and descriptive models have been proposed since the beginning of the 20th century. In the present study, the power-law (Kennelly) and logarithmic (Péronnet-Thibault) models were compared with asymptotic models such as 2-parameter hyperbolic models (Hill and Scherrer), 3-parameter hyperbolic model (Morton), and exponential model (Hopkins). These empirical models were compared from the performance of 6 elite endurance runners (P. Nurmi, E. Zatopek, J. Väätäinen, L. Virén, S. Aouita, and H. Gebrselassie) who were world-record holders and/or Olympic winners and/or world or European champions. These elite runners were chosen because they participated several times in international competitions over a large range of distances (1500, 3000, 5000, and 10000 m) and three also participated in a marathon. The parameters of these models were compared and correlated. The less accurate models were the asymptotic 2-parameter hyperbolic models but the most accurate model was the asymptotic 3-parameter hyperbolic model proposed by Morton. The predictions of long-distance performances (maximal running speeds for 30 and 60 min and marathon) by extrapolation of the logarithmic and power-law models were more accurate than the predictions by extrapolation in all the asymptotic models. The overestimations of these long-distance performances by Morton's model were less important than the overestimations by the other asymptotic models.

Application of the Athlete's Performance Passport for Doping Control: A Case Report

The efficient use of testing resources is a key issue in the fight against doping. The longitudinal tracking of sporting performances to identify unusual improvements possibly caused by doping, so-called “athlete's performance passport” (APP) is a new concept to improve targeted anti-doping testing. In fact, unusual performances by an athlete would trigger a more thorough testing program. In the present case report, performance data is modeled using the critical power concept for a group of athletes based on their past performances. By these means, an athlete with unusual deviations from his predicted performances was identified. Subsequent target testing using blood testing and the athlete biological passport resulted in an anti-doping rule violation procedure and suspension of the athlete. This case demonstrates the feasibility of the APP approach where athlete's performance is monitored and might serve as an example for the practical implementation of the method.

Topical and Ingested Cooling Methodologies for Endurance Exercise Performance in the Heat

This systematic review and meta-analysis aimed to assess studies which have investigated cooling methodologies, their timing and effects, on endurance exercise performance in trained athletes (Category 3; VO_2max ≥ 55 mL·kg·min⁻¹) in hot environmental conditions (≥28 °C). Meta-analyses were performed to quantify the effects of timings and methods of application, with a narrative review of the evidence also provided. A computer-assisted database search was performed for articles investigating the effects of cooling on endurance performance and accompanying physiological and perceptual responses. A total of 4129 results were screened by title, abstract, and full text, resulting in 10 articles being included for subsequent analyses. A total of 101 participants and 310 observations from 10 studies measuring the effects of differing cooling strategies on endurance exercise performance and accompanying physiological and perceptual responses were included. With respect to time trial performance, cooling was shown to result in small beneficial effects when applied before and throughout the exercise bout (Effect Size: −0.44; −0.69 to −0.18), especially when ingested (−0.39; −0.60 to −0.18). Current evidence suggests that whilst other strategies ameliorate physiological or perceptual responses throughout endurance exercise in hot conditions, ingesting cooling aids before and during exercise provides a small benefit, which is of practical significance to athletes’ time trial performance.

Different durations within the method of best practice affect the parameters of the speed-duration relationship

The aim of the study was to determine whether estimates of the speed-duration relationship are affected using different time-trial (TT) field-based testing protocols, where exhaustive times were located within the generally recommended durations of 2-15 min. Ten triathletes (mean ± SD age: 31.0 ± 5.7 years; height: 1.81 ± 0.05 m; body mass: 76.5 ± 6.8 kg) performed two randomly assigned field tests to determine critical speed (CS) and the total distance covered above CS (D́). CS and D́ were obtained using two different protocols comprising three TT that were interspersed by 60 min passive rest. The TTs were 12, 7, and 3 min in Protocol I and 10, 5, and 2 min in Protocol II. A linear relationship of speed vs. the inverse of time (s = D́ × 1/t + CS) was used to determine parameter estimates. Significant differences were found for CS (p = 0.026), but not for D́ (p = 0.123). The effect size for CS (d = 0.305) was considered small, while that for D́ was considered moderate (d = 0.742). CS was significantly correlated between protocols (r = 0.934; p < 0.001), however, no correlation was found for D́ (r = 0.053; p = 0.884). The 95% limits of agreement were ±0.28m s^-1 and ±73.9 m for CS and D́, respectively. These findings demonstrate that the choice of exhaustive times within commonly accepted durations results in different estimates of CS and D́, and thus protocols cannot be used interchangeably. The use of a consistent protocol is therefore recommended, when investigating or monitoring the speed-duration relationship estimates in well-trained athletes.

Performance Profiling-Perspectives for Anti-doping and beyond

Performance profiling is a new area of research that could potentially open new frontiers in the fight against doping. Even beyond exposing unnatural and pharmacology aided performances, there are other potential applications and benefits of performance modeling for the protection of the integrity of sports. The backbone of performance modeling in anti-doping is the individual tracking of performance through competition results or other metrics of sporting achievements. Since performance improvement is the primary goal of doping, it is expected that doping will affect competition results. Thus, individual tracking of performance could potentially expose suspicious cases that deserve more scrutiny from anti-doping officials and help to adjust targeted testing. On the other hand changes in performance levels could also be used to assess the efficiency of new anti-doping strategies. Another application of performance analysis is to develop unified classifications of athletes according to their level of performance. This classification has numerous practical meanings, but from anti-doping perspective it provides an opportunity to set exact criteria for athletes belonging to national and international testing pools and thus estimate the number of tests needed in different countries based on the number of athletes at ascertain performance level. At the moment, in the absence of unified and comprehensive criteria for national and international testing pools, there are no definitive regulations regarding exact doping test numbers needed. Thus, it creates inequality between nations and affects the credibility of the anti-doping system worldwide. Such classification would allow a more efficient use of anti-doping resources. Since doping is not the only threat to the integrity of sports, performance modeling can also help to reveal cases of other misbehavior in sports, like match fixing or result manipulation. In summary, performance modeling and its application to various fields is a new method to improve the efficiency of systems to safeguard the integrity of sports at different levels.

Temperate Performance Benefits after Heat, but Not Combined Heat and Hypoxic Training

PURPOSE

Independent heat and hypoxic exposure can enhance temperate endurance performance in trained athletes, although their combined effects remain unknown. This study examined whether the addition of heat interval training during "live high, train low" (LHTL) hypoxic exposure would result in enhanced performance and physiological adaptations as compared with heat or temperate training.

METHODS

Twenty-six well-trained runners completed 3 wk of interval training assigned to one of three conditions: 1) LHTL hypoxic exposure plus heat training (H + H; 3000 m for 13 h·d, train at 33°C, 60% relative humidity [RH]), 2) heat training with no hypoxic exposure (HOT, live at <600 m and train at 33°C, 60% RH), or 3) temperate training with no hypoxic exposure (CONT; live at <600 m and train at 14°C, 55% RH). Performance 3-km time-trials (3-km TT), running economy, hemoglobin mass, and plasma volume were assessed using magnitude-based inferences statistical approach before (Baseline), after (Post), and 3 wk (3wkP) after exposure.

RESULTS

Compared with Baseline, 3-km TT performance was likely increased in HOT at 3wkP (-3.3% ± 1.3%; mean ± 90% confidence interval), with no performance improvement in either H + H or CONT. Hemoglobin mass increased by 3.8% ± 1.8% at Post in H + H only. Plasma volume in HOT was possibly elevated above H + H and CONT at Post but not at 3wkP. Correlations between changes in 3-km TT performance and physiological adaptations were unclear.

CONCLUSION

Incorporating heat-based training into a 3-wk training block can improve temperate performance at 3 wk after exposure, with athlete psychology, physiology, and environmental dose all important considerations. Despite hematological adaptations, the addition of LHTL to heat interval training has no greater 3-km TT performance benefit than temperate training alone.

Intra-Subject Variability of 5 km Time Trial Performance Completed by Competitive Trained Runners

Time-trials represent an ecologically valid approach to assessment of endurance performance. Such information is useful in the application of testing protocols and estimation of sample sizes required for research/magnitude based inference methods. The present study aimed to investigate the intra-subject variability of 5 km time-trial running performance in trained runners. Six competitive trained male runners (age = 33.8 ± 10.1 years; stature = 1.78 ± 0.01 m; body mass = 69.0 ± 10.4 kg, V.O_2max = 62.6 ± 11.0 ml·kg·min^-1) completed an incremental exercise test to volitional exhaustion followed by 5 x 5 km time-trials (including a familiarisation trial), individually spaced by 48 hours. The time taken to complete each trial, heart rate, rating of perceived exertion and speed were all assessed. Intra-subject absolute standard error of measurement and the coefficient of variance were calculated for time-trial variables in addition to the intra-class correlation coefficient for time taken to complete the time-trial. For the primary measure time, results showed a coefficient of variation score across all participants of 1.5 ± 0.59% with an intra-class correlation coefficient score of 0.990. Heart rate, rating of perceived exertion and speed data showed a variance range between 0.8 and 3.05%. It was concluded that when compared with related research, there was observed low intra-subject variability in trained runners over a 5 km distance. This supports the use of this protocol for 5 km time-trial performance for assessment of nutritional strategies, ergogenic aids or training interventions on endurance running performance.

Lower Limb and Trunk Biomechanics After Fatigue in Competitive Female Irish Dancers

CONTEXT

  Because of the increasing popularity of participation in Irish dance, the incidence of lower limb injuries is high among this competitive population.

OBJECTIVE

  To investigate the effects of fatigue on the peak lower limb and trunk angles as well as the peak lower limb joint forces and moments of competitive female Irish dancers during the performance of a dance-specific single-limb landing.

DESIGN

  Cross-sectional study.

SETTING

  Laboratory.

PATIENTS OR OTHER PARTICIPANTS

  Fourteen healthy, female, competitive Irish dancers (age = 19.4 ± 3.7 years, height = 165.3 ± 5.9 cm, mass = 57.9 ± 8.2 kg).

INTERVENTION(S)

  Participants performed an Irish dance-specific leap before and after a dance-specific fatigue protocol. During each landing movement, 3-dimensional lower limb kinematics (250 Hz) and ground reaction forces (1000 Hz) were collected. Paired t tests were performed to determine the differences (P ≤ .05) in lower limb and trunk biomechanics prefatigue and postfatigue.

MAIN OUTCOME MEASURE(S)

  Peak lower limb and trunk angles as well as peak lower limb joint reaction forces and external moments.

RESULTS

  Compared with the prefatigue trials, dancers landed with reduced ankle plantar flexion (P = .003) and hip external rotation (P = .007) and increased hip-adduction alignment (P = .034) postfatigue. Dancers displayed greater anterior shear (P = .003) and compressive (P = .024) forces at the ankle and greater external knee-flexion moments (P = .024) during the postfatigue compared with the prefatigue landing trials.

CONCLUSIONS

  When fatigued, dancers displayed a decline in landing performance in terms of aesthetics as well as increased ankle- and knee-joint loading, potentially exposing them to a greater risk of injuries.

Assessment of evertor weakness in patients with chronic ankle instability: Functional versus isokinetic testing

BACKGROUND

Ankle sprain is the most common sport-related injury and eccentric weakness of ankle evertors is regarded as a significant muscular deficit related to chronic ankle instability. However, the eccentric performance of the evertors is rarely assessed by clinicians because procedures used for research purposes (i.e. isokinetic tests) are not easily applicable in daily practice.

METHODS

The present study assessed the ability of two different testing procedures to distinguish between groups of 12 healthy subjects or 12 patients suffering from chronic ankle instability. On the one hand, the strength of evertors was assessed with a goldstandard isokinetic procedure. On the other hand, we assessed the ability of the subjects to control ankle inversion during weight bearing (functional standing test).

FINDINGS

Data showed no significant difference between groups for isokinetic peak torque values normalized to body weight. Conversely, the functional test revealed a significantly impaired ability to control ankle inversion during weight bearing in subjects with chronic ankle instability.

INTERPRETATION

This suggests that this easy-to-apply functional test is better suited compared to isokinetic testing procedures to assess weakness of evertors in patients suffering from chronic ankle instability. Moreover, this test may also be used to objectively monitor improvements during rehabilitation or progression in prevention protocols.

Does Carbohydrate Intake During Endurance Running Improve Performance? A Critical Review

Wilson, PB. Does carbohydrate intake during endurance running improve performance? A critical review. J Strength Cond Res 30(12): 3539-3559, 2016-Previous review articles assessing the effects of carbohydrate ingestion during prolonged exercise have not focused on running. Given the popularity of distance running and the widespread use of carbohydrate supplements, this article reviewed the evidence for carbohydrate ingestion during endurance running. The criteria for inclusion were (a) experimental studies reported in English language including a performance task, (b) moderate-to-high intensity exercise >60 minutes (intermittent excluded), and (c) carbohydrate ingestion (mouth rinsing excluded). Thirty studies were identified with 76 women and 505 men. Thirteen of the 17 studies comparing a carbohydrate beverage(s) with water or a placebo found a between-condition performance benefit with carbohydrate, although heterogeneity in protocols precludes clear generalizations about the expected effect sizes. Additional evidence suggests that (a) performance benefits are most likely to occur during events >2 hours, although several studies showed benefits for tasks lasting 90-120 minutes; (b) consuming carbohydrate beverages above ad libitum levels increases gastrointestinal discomfort without improving performance; (c) carbohydrate gels do not influence performance for events lasting 16-21 km; and (d) multiple saccharides may benefit events >2 hours if intake is ≥1.3 g·min Given that most participants were fasted young men, inferences regarding women, adolescents, older runners, and those competing in fed conditions are hampered. Future studies should address these limitations to further elucidate the role of carbohydrate ingestion during endurance running.

Echinacea Supplementation: Does it Really Improve Aerobic Fitness?

PURPOSE

Echinacea is an herbal supplement used by endurance athletes for its performance boosting properties. It is thought that Echinacea improves the blood's oxygen carrying capacity by increasing production of erythropoietin (EPO), a glycoprotein that regulates red blood cell formation. Subsequently, these changes would lead to an overall improvement in maximal oxygen uptake (VO2max) and running economy (RE), two markers of aerobic fitness. The purpose of this review is to briefly discuss the physiological variables associated with distance running performance and how these variables are influenced by Echinacea supplementation.

METHODS

To determine Echinacea's ergogenic potential, human studies that used Echinacea in conjunction to analyzing the blood's oxygen carrying capacity and/or aerobic fitness were assessed.

RESULTS

Taken together, the majority of the published literature does not support the claim that Echinacea is a beneficial ergogenic aid. With the exception of one study, several independent groups have reported Echinacea supplementation does not increase EPO production, blood markers of oxygen transport, VO2max or RE in healthy untrained or trained subjects.

CONCLUSION

To date, the published literature does not support the use of Echinacea as an ergogenic aid to improve aerobic fitness in healthy untrained or trained subjects.

VO2max Measured with a Self-selected Work Rate Protocol on an Automated Treadmill

PURPOSE

The use of graded maximal exercise tests for measuring maximal oxygen consumption (VO2max) is common practice in both cardiopulmonary rehabilitation settings and in sports medicine research. Recent alterations of common testing protocols to allow for self-selected work rates (SPV) have elicited V˙O2max values similar to or higher than more traditional style protocols (TP). Research is lacking in the delivery of the SPV protocol using a treadmill modality. The purpose of the study was to examine the validity of an SPV using an automated treadmill for measuring cardiorespiratory fitness.

METHODS

Thirteen experienced endurance runners completed three maximal exercise tests on a treadmill. Oxygen consumption was measured using a computerized system and averaged more than 30-s time periods. SPV was completed using an automated treadmill that consisted of a sonar range finder, microcontroller, and customized computer software. Subject deviations from the middle of the treadmill belt resulted in rapid, graded increases or decreases in speed. TP was completed on the same treadmill without the use of the automated software. A verification phase protocol (VP) was used to verify if VO2 was maximal.

RESULTS

Peak work rate achieved during SPV was significantly greater than that achieved during TP by 1.2 METs; P < 0.05, d = 0.564. Oxygen consumption was significantly greater in TP (64.9 ± 8.2 mL·kg·min) than SPV (63.4 ± 7.8 mL·kg·min); P < 0.005, d = 0.195.

CONCLUSION

An automated treadmill allowed for the completion of SPV similar to what has been reported for cycling. SPV with an automated treadmill did not provide a higher VO2max than TP despite higher work rates.

Altitude training for elite endurance athletes: A review for the travel medicine practitioner

High altitude training is regarded as an integral component of modern athletic preparation, especially for endurance sports such as middle and long distance running. It has rapidly achieved popularity among elite endurance athletes and their coaches. Increased hypoxic stress at altitude facilitates key physiological adaptations within the athlete, which in turn may lead to improvements in sea-level athletic performance. Despite much research in this area to date, the exact mechanisms which underlie such improvements remain to be fully elucidated. This review describes the current understanding of physiological adaptation to high altitude training and its implications for athletic performance. It also discusses the rationale and main effects of different training models currently employed to maximise performance. Athletes who travel to altitude for training purposes are at risk of suffering the detrimental effects of altitude. Altitude illness, weight loss, immune suppression and sleep disturbance may serve to limit athletic performance. This review provides an overview of potential problems which an athlete may experience at altitude, and offers specific training recommendations so that these detrimental effects are minimised.

Nighttime feeding likely alters morning metabolism but not exercise performance in female athletes

The timing of morning endurance competition may limit proper pre-race fueling and resulting performance. A nighttime, pre-sleep nutritional strategy could be an alternative method to target the metabolic and hydrating needs of the early morning athlete without compromising sleep or gastrointestinal comfort during exercise. Therefore, the purpose of this investigation was to examine the acute effects of pre-sleep chocolate milk (CM) ingestion on next-morning running performance, metabolism, and hydration status. Twelve competitive female runners and triathletes (age, 30 ± 7 years; peak oxygen consumption, 53 ± 4 mL·kg(-1)·min(-1)) randomly ingested either pre-sleep CM or non-nutritive placebo (PL) ∼30 min before sleep and 7-9 h before a morning exercise trial. Resting metabolic rate (RMR) was assessed prior to exercise. The exercise trial included a warm-up, three 5-min incremental workloads at 55%, 65%, and 75% peak oxygen consumption, and a 10-km treadmill time trial (TT). Physiological responses were assessed prior, during (incremental and TT), and postexercise. Paired t tests and magnitude-based inferences were used to determine treatment differences. TT performances were not different ("most likely trivial" improvement with CM) between conditions (PL: 52.8 ± 8.4 min vs CM: 52.8 ± 8.0 min). RMR was "likely" increased (4.8%) and total carbohydrate oxidation (g·min(-1)) during exercise was "possibly" or likely increased (18.8%, 10.1%, 9.1% for stage 1-3, respectively) with CM versus PL. There were no consistent changes to hydration indices. In conclusion, pre-sleep CM may alter next-morning resting and exercise metabolism to favor carbohydrate oxidation, but effects did not translate to 10-km running performance improvements.

Sources of Variability in Performance Times at the World Orienteering Championships

PURPOSE

An improvement equal to 0.3 of the typical variation in an elite athlete's race-to-race performance estimates the smallest worthwhile enhancement, which has not yet been determined for orienteers. Moreover, much of the research in high-performance orienteering has focused on physical and cognitive aspects, although course characteristics might influence race performance. Analysis of race data provides insights into environmental effects and other aspects of competitive performance. Our aim was to examine such factors in relation to World Orienteering Championships performances.

METHODS

We used mixed linear modelling to analyze finishing times from the three qualification rounds and final round of the sprint, middle-distance, and long-distance disciplines of World Orienteering Championships from 2006 to 2013. Models accounted for race length, distance climbed, number of controls, home advantage, venue identity, round (qualification final), athlete identity, and athlete age.

RESULTS

Within-athlete variability (coefficient of variation, mean ± SD) was lower in the final (4.9% ± 1.4%) than in the qualification (7.3% ± 2.4%) rounds and provided estimates of smallest worthwhile enhancements of 1.0%-3.5%. The home advantage was clear in most disciplines, with distance climbed particularly impacting sprint performances. Small to very large between-venue differences were apparent. Performance predictability expressed as intraclass correlation coefficients was extremely high within years and was high to very high between years. Age of peak performance ranged from 27 to 31 yr.

CONCLUSIONS

Our results suggest that elite orienteers should focus on training and strategies that enhance performance by at least 1.0%-3.5% for smallest worthwhile enhancement. Moreover, as greater familiarity with the terrain likely mediated the home advantage, foreign athletes would benefit from training in nations hosting the World Orienteering Championships for familiarization.

A comparison of methods for determining the rate of force development during isometric midthigh clean pulls

Twelve female division I collegiate volleyball players were recruited to examine the reliability of several methods for calculating the rate of force development (RFD) during the isometric midthigh clean pull. All subjects were familiarized with the isometric midthigh clean pull and participated in regular strength training. Two isometric midthigh clean pulls were performed with 2 minutes rest between each trail. All measures were performed in a custom isometric testing device that included a step-wise adjustable bar and a force plate for measuring ground reaction forces. The RFD during predetermined time zone bands (0-30, 0-50, 0-90, 0-100, 0-150, 0-200, and 0-250 milliseconds) was then calculated by dividing the force at the end of the band by the band's time interval. The peak RFD was then calculated with the use of 2, 5, 10, 20, 30, and 50 milliseconds sampling windows. The average RFD (avgRFD) was calculated by dividing the peak force (PF) by the time to achieve PF. All data were analyzed with the use of intraclass correlation alpha (ICCα) and the coefficient of variation (CV) and 90% confidence intervals. All predetermined RFD time bands were deemed reliable based on an ICCα >0.95 and a CV <4%. Conversely, the avgRFD failed to meet the reliability standards set for this study. Overall, the method used to assess the RFD during an isometric midthigh clean pull impacts the reliability of the measure and predetermined RFD time bands should be used to quantify the RFD.

Cluster Stability as a New Method to Assess Changes in Performance and its Determinant Factors Over a Season in Young Swimmers

Purpose:

To apply a new method to identify, classify, and follow up young swimmers based on their performance and its determinant factors over a season and analyze the swimmers’ stability over a competitive season with that method.

Methods:

Fifteen boys and 18 girls (11.8 ± 0.7 y) part of a national talent-identification scheme were evaluated at 3 different moments of a competitive season. Performance (ie, official 100-m freestyle race time), arm span, chest perimeter, stroke length, swimming velocity, speed fluctuation, coefficient of active drag, propelling efficiency, and stroke index were selected as variables. Hierarchical and k-means cluster analysis were computed.

Results:

Data suggested a 3-cluster solution, splitting the swimmers according to their performance in all 3 moments. Cluster 1 was related to better performances (talented swimmers), cluster 2 to poor performances (nonproficient swimmers), and cluster 3 to average performance (proficient swimmers) in all moments. Stepwise discriminant analysis revealed that 100%, 94%, and 85% of original groups were correctly classified for the 1st, 2nd, and 3rd evaluation moments, respectively (0.11 ≤ Λ ≤ 0.80; 5.64 ≤ χ2 ≤ 63.40; 0.001 < P ≤ .68). Membership of clusters was moderately stable over the season (stability range 46.1–75% for the 2 clusters with most subjects).

Conclusion:

Cluster stability is a feasible, comprehensive, and informative method to gain insight into changes in performance and its determinant factors in young swimmers. Talented swimmers were characterized by anthropometrics and kinematic features.

The reliability of isoinertial force-velocity-power profiling and maximal strength assessment in youth

The purpose of this study was to quantify the inter-session reliability of force-velocity-power profiling and estimated maximal strength in youth. Thirty-six males (11-15 years old) performed a ballistic supine leg press test at five randomized loads (80%, 100%, 120%, 140%, and 160% body mass) on three separate occasions. Peak and mean force, power, velocity, and peak displacement were collected with a linear position transducer attached to the weight stack. Mean values at each load were used to calculate different regression lines and estimate maximal strength, force, velocity, and power. All variables were found reliable (change in the mean [CIM] = - 1 to 14%; coefficient of variation [CV] = 3-18%; intraclass correlation coefficient [ICC] = 0.74-0.99), but were likely to benefit from a familiarization, apart from the unreliable maximal force/velocity ratio (CIM = 0-3%; CV = 23-25%; ICC = 0.35-0.54) and load at maximal power (CIM = - 1 to 2%; CV = 10-13%; ICC = 0.26-0.61). Isoinertial force-velocity-power profiling and maximal strength in youth can be assessed after a familiarization session. Such profiling may provide valuable insight into neuromuscular capabilities during growth and maturation and may be used to monitor specific training adaptations.

Performance in the heat-physiological factors of importance for hyperthermia-induced fatigue

This article presents a historical overview and an up-to-date review of hyperthermia-induced fatigue during exercise in the heat. Exercise in the heat is associated with a thermoregulatory burden which mediates cardiovascular challenges and influence the cerebral function, increase the pulmonary ventilation, and alter muscle metabolism; which all potentially may contribute to fatigue and impair the ability to sustain power output during aerobic exercise. For maximal intensity exercise, the performance impairment is clearly influenced by cardiovascular limitations to simultaneously support thermoregulation and oxygen delivery to the active skeletal muscle. In contrast, during submaximal intensity exercise at a fixed intensity, muscle blood flow and oxygen consumption remain unchanged and the potential influence from cardiovascular stressing and/or high skin temperature is not related to decreased oxygen delivery to the skeletal muscles. Regardless, performance is markedly deteriorated and exercise-induced hyperthermia is associated with central fatigue as indicated by impaired ability to sustain maximal muscle activation during sustained contractions. The central fatigue appears to be influenced by neurotransmitter activity of the dopaminergic system, but inhibitory signals from thermoreceptors arising secondary to the elevated core, muscle and skin temperatures and augmented afferent feedback from the increased ventilation and the cardiovascular stressing (perhaps baroreceptor sensing of blood pressure stability) and metabolic alterations within the skeletal muscles are likely all factors of importance for afferent feedback to mediate hyperthermia-induced fatigue during submaximal intensity exercise. Taking all the potential factors into account, we propose an integrative model that may help understanding the interplay among factors, but also acknowledging that the influence from a given factor depends on the exercise hyperthermia situation.

Physical and perceptual cooling with beverages to increase cycle performance in a tropical climate

Purpose

This study compares the effects of neutral temperature, cold and ice-slush beverages, with and without 0.5% menthol on cycling performance, core temperature (T_co) and stress responses in a tropical climate (hot and humid conditions).

Methods

Twelve trained male cyclists/triathletes completed six 20-km exercise trials against the clock in 30.7°C±0.8°C and 78%±0.03% relative humidity. Before and after warm-up, and before exercise and every 5 km during exercise, athletes drank 190 mL of either aromatized (i.e., with 0.5 mL of menthol (5 gr/L)) or a non-aromatized beverage (neutral temperature: 23°C±0.1°C, cold: 3°C±0.1°C, or ice-slush: −1°C±0.7°C). During the trials, heart rate (HR) was continuously monitored, whereas core temperature (T_co), thermal comfort (TC), thermal sensation (TS) and rate of perceived exertion (RPE) were measured before and after warm-up, every 5 km of exercise, and at the end of exercise and after recovery.

Results

Both the beverage aroma (P<0.02) and beverage temperature (P<0.02) had significant and positive effects on performance, which was considerably better with ice-slush than with a neutral temperature beverage, whatever the aroma (P<0.002), and with menthol vs non-menthol (P<0.02). The best performances were obtained with ice-slush/menthol and cold/menthol, as opposed to neutral/menthol. No differences were noted in HR and T_co between trials.

Conclusion

Cold water or ice-slush with menthol aroma seems to be the most effective beverage for endurance exercise in a tropical climate. Further studies are needed to explore its effects in field competition.

Effects of resistance training on running economy and cross-country performance

PURPOSE

Heavy-resistance training and plyometric training offer distinct physiological and neuromuscular adaptations that could enhance running economy and, consequently, distance-running performance. To date, no studies have examined the effect of combining the two modes of training on running economy or performance.

METHODS

Fifty collegiate male and female cross-country runners performed a 5-km time trial and a series of laboratory-based tests to determine aerobic, anthropometric, biomechanical, and neuromuscular characteristics. Thereafter, each athlete participated in a season of six to eight collegiate cross-country races for 13 wk. After the first 4 wk, athletes were randomly assigned to either heavy-resistance or plyometric plus heavy-resistance training. Five days after completing their final competition, runners repeated the same set of laboratory tests. We also estimated the effects of the intervention on competition performance throughout the season using athletes of other teams as controls.

RESULTS

Heavy-resistance training produced small-moderate improvements in peak speed, running economy, and neuromuscular characteristics relative to plyometric resistance training, whereas changes in biomechanical measures favored plyometric resistance training. Men made less gains than women in most tests. Both treatments had possibly harmful effects on competition times in men (mean = 0.5%; 90% confidence interval = ±1.2%), but there may have been benefit for some individuals. Both treatments were likely beneficial for all women (-1.2%; ±1.3%), but heavy-resistance training was possibly better than plyometric resistance training.

CONCLUSIONS

The changes in laboratory-based parameters related to distance-running performance were consistent with the changes in competition times for women but only partly for men. Our data indicate that women should include heavy-resistance training in their programs, but men should be cautious about using it in season until more research establishes whether certain men are positive or negative responders.

Physiological and psychological effects of deception on pacing strategy and performance: a review

The aim of an optimal pacing strategy during exercise is to enhance performance whilst ensuring physiological limits are not surpassed, which has been shown to result in a metabolic reserve at the end of the exercise. There has been debate surrounding the theoretical models that have been proposed to explain how pace is regulated, with more recent research investigating a central control of exercise regulation. Deception has recently emerged as a common, practical approach to manipulate key variables during exercise. There are a number of ways in which deception interventions have been designed, each intending to gain particular insights into pacing behaviour and performance. Deception methodologies can be conceptualised according to a number of dimensions such as deception timing (prior to or during exercise), presentation frequency (blind, discontinuous or continuous) and type of deception (performance, biofeedback or environmental feedback). However, research evidence on the effects of deception has been perplexing and the use of complex designs and varied methodologies makes it difficult to draw any definitive conclusions about how pacing strategy and performance are affected by deception. This review examines existing research in the area of deception and pacing strategies, and provides a critical appraisal of the different methodological approaches used to date. It is hoped that this analysis will inform the direction and methodology of future investigations in this area by addressing the mechanisms through which deception impacts upon performance and by elucidating the potential application of deception techniques in training and competitive settings.

A systematic review of the efficacy of ergogenic aids for improving running performance

Running is a common form of activity worldwide, and participants range from "weekend warriors" to Olympians. Unfortunately, few studies have examined efficacy of various ergogenic aids in runners because the majority of the literature consists of cycling-based protocols, which do not relate to running performance. The majority of running studies conducted markedly vary in regards to specific distance completed, subject fitness level, and effectiveness of the ergogenic aid examined. The aim of this article was to systematically examine the literature concerning utility of several ergogenic aids on middle-distance running (400-5,000 m) and long-distance running (10,000 meters marathon = 42.2 km) performance. In addition, this article highlights the dearth of running-specific studies in the literature and addresses recommendations for future research to optimize running performance through nutritional intervention. Results revealed 23 studies examining effects of various ergogenic aids on running performance, with a mean Physiotherapy Evidence Database score equal to 7.85 ± 0.70. Of these studies, 71% (n = 15) demonstrated improved running performance with ergogenic aid ingestion when compared with a placebo trial. The most effective ergogenic aids for distances from 400 m to 40 km included sodium bicarbonate (4 studies; 1.5 ± 1.1% improvement), sodium citrate (6 studies; 0.3 ± 1.7% improvement), caffeine (CAFF) (7 studies; 1.1 ± 0.4% improvement), and carbohydrate (CHO) (6 studies; 4.1 ± 4.4% improvement). Therefore, runners may benefit from ingestion of sodium bicarbonate to enhance middle distance performance and caffeine and carbohydrate to enhance performance at multiple distances.

Pacing by winners of a 161-km mountain ultramarathon

PURPOSE

To examine pacing among the most successful runners in the 161-km Western States Endurance Run (WSER) to determine if variations in segmental speed relate to performance, ambient temperature, and calendar year.

METHODS

Segmental speed and coefficient of variation (CV) in speed were analyzed for 10 race segments of 24 races from 1985 through 2013.

RESULTS

Segmental speeds did not differ between the eventual winners and lead runners and only differed between the 1st and 2nd finishers in the 2nd half of the race. Mean CV in speed was lower (P < .01) for the winners (12%) than for the other top-5 finishers (14-15%). CV in speed was related (r = .80, P = .006) to finish time for the fastest 10 finish times at the WSER. Multiple linear-regression analysis revealed mean CV in speed for the top-5 runners to be related to maximum ambient temperature (coefficient =.14, P < .05) and calendar year (coefficient = -.086, P = .034).

CONCLUSIONS

Mountain trail running is characterized by wide variations in speed, but the fastest times are achieved when speed fluctuations are limited. This is generally accomplished by the winners remaining relatively close behind the lead runners before taking the lead in the middle half of the race, and then avoiding slowing as much as the other top runners in the latter race stages. Variations in speed increase with high ambient temperatures, and the small decrease in segmental speed variability among top runners across the nearly 30 y of this study suggests that the best runners have improved at pacing this race.