Años de experiencia como factor limitante en corredores veteranos de largas distancias / Training experience as a limiting factor in master long distance runners

En las últimas décadas ha aumentado el número de atletas veteranos en carreras populares de resistencia. El estudio, que incluyó 103 atletas, tuvo el objetivo de analizar cómo influye la edad y los años de experiencia en el rendimiento de corredores veteranos en largas distancias. Para ello se elaboró un cuestionario ad hoc. El análisis de los años de experiencia muestra correlaciones significativas (p<0,05) en todas las distancias de la categoría de 35-39 años, así como en la distancia de 21,1 km en categoría 40-44 años. Por otro lado, en la comparación entre categorías relacionados con el tiempo total, se encontraron diferencias significativas en la distancia de 21,1 km para los grupos de edad de 35-39/45-49 (p=0,014) y 35-39/50-54 (p=0,014) así como en la distancia de 42,2 km para los grupos de edad de 35-39/45-49 (p=0,022) y 45-49/50-54 (p=0,050). Los años de experiencia parecen ser un factor limitante del rendimiento (AU)

In the last decades, the number of recreational master runners in long-distance running events has increased. This study, which included 103 runners, aimed to analyze the influence of age and training experience on master runners' performance over long distances. An ad hoc questionnaire was used. Training experience analysis showed significant correlations (p<0.05) in all distances in the 35-39 years category, as well as in the distance of 21.1 km in the 40-44 years category. Furthermore, in the comparison between categories related to the total time, significant differences were found in 21.1 km distance for age groups of 35-39 / 45-49 (p=0.014) and 35-39 / 50-54 (p= 0.014) as well as in 42.2 km distance for the age groups of 35-39 / 45-49 (p=0.022) and 45-49 / 50-54 (p=0.050). Training experience appears to be a limiting factor for performance in recreational master runners (AU)

Are gait characteristics and ground reaction forces related to energy cost of running in elite Kenyan runners?

The aim of this study was to determine whether gait cycle characteristics are associated with running economy in elite Kenyan runners. Fifteen elite Kenyan male runners completed two constant-speed running sets on a treadmill (12 km ·h-1 and 20 km ·h-1). VO2 and respiratory exchange ratio values were measured to calculate steady-state oxygen and energy cost of running. Gait cycle characteristics and ground contact forces were measured at each speed. Oxygen cost of running at different velocities was 192.2 ± 14.7 ml· kg-1· km-1 at 12 km· h-1 and 184.8 ± 9.9 ml· kg-1· km-1 at 20 km· h-1, which corresponded to a caloric cost of running of 0.94 ± 0.07 kcal ·kg-1·km-1 and 0.93 ± 0.07 kcal· kg-1· km-1. We found no significant correlations between oxygen and energy cost of running and biomechanical variables and ground reaction forces at either 12 or 20 km· h-1. However, ground contact times were ~10.0% shorter (very large effect) than in previously published literature in elite runners at similar speeds, alongside an 8.9% lower oxygen cost (very large effect). These results provide evidence to hypothesise that the short ground contact times may contribute to the exceptional running economy of Kenyan runners.

Effect on Oxygen Cost of Transport from 8-Weeks of Progressive Training with Barefoot Running.

Popular interest in barefoot running has emerged as a result of its alleged performance and injury prevention benefits. Oxygen cost of transport (COT) improvements from barefoot running, however, remains equivocal. The aim of this study was to determine the influence of an 8-week progressive barefoot training program on COT and associated spatiotemporal variables. 15 male runners participated in this study. Variables such as oxygen uptake, biomechanical and spatiotemporal characteristics of gait, including ground contact (GC) and swing time; stride length and frequency and ankle plantar-dorsiflexion were measured pre- and post-intervention. The COT did not differ between barefoot and shod running either pre- or post-training. Improved barefoot COT (p<0.05) but not shod was found between pre- and post-training. Biomechanical differences between barefoot and shod conditions persisted over the training period. A decrease in barefoot COT was associated with a decrease in GC time (p=0.003, r=0.688) and a small increase in stride frequency (p=0.030; r=0.569). Ground contact time and stride frequency, previously associated with COT, only partly contribute (32% - Stride frequency and 47% - GC time) to a decrease in COT after barefoot training. Thus other physiological and biomechanical variables must influence the improvement in COT after a barefoot training intervention.

Maintained cerebral oxygenation during maximal self-paced exercise in elite Kenyan runners.

The purpose of this study was to analyze the cerebral oxygenation response to maximal self-paced and incremental exercise in elite Kenyan runners from the Kalenjin tribe. On two separate occasions, 15 elite Kenyan distance runners completed a 5-km time trial (TT) and a peak treadmill speed test (PTS). Changes in cerebral oxygenation were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxyhemoglobin (Δ[O2Hb] and Δ[HHb]), tissue oxygenation index (TOI), and total hemoglobin index (nTHI). During the 5-km TT (15.2 ± 0.2 min), cerebral oxygenation increased over the first half (increased Δ[O2Hb] and Δ[HHb]) and, thereafter, Δ[O2Hb] remained constant (effect size, ES = 0.33, small effect), whereas Δ[HHb] increased until the end of the trial (P < 0.05, ES = 3.13, large effect). In contrast, during the PTS, from the speed corresponding to the second ventilatory threshold, Δ[O2Hb] decreased (P < 0.05, ES = 1.51, large effect), whereas Δ[HHb] continued to increase progressively until exhaustion (P < 0.05, ES = 1.22, large effect). Last, the TOI was higher during the PTS than during the 5-km TT (P < 0.001, ES = 3.08; very large effect), whereas nTHI values were lower (P < 0.001, ES = 2.36, large effect). This study shows that Kenyan runners from the Kalenjin tribe are able to maintain their cerebral oxygenation within a stable range during a self-paced maximal 5-km time trial, but not during an incremental maximal test. This may contribute to their long-distance running success.

Longitudinal field test assessment in a Basque soccer youth academy: a multilevel modeling framework to partition effects of maturation.

The purpose of the study was to examine the effect of age on short-term performance indicators applying multilevel regression modeling, and whether changes induced by age were affected by maturation. The study applied a mixed longitudinal approach with 8 measurement points over a period of 4 years. Anthropometry, predicted adult stature, countermovement jump, 15-m sprint and agility test from 38 under-11 young soccer players were considered. Early maturing players were 3% taller compared to late maturers. A substantial effect of age was present in all performance indicators (P<0.05). Parameters showed improvements in performance, even when accounting for interindividual variation in somatic maturity. Vertical jump tended to be stable in early maturers during the first year, presenting an exponential increase thereafter (16%, P<0.05). Additionally, early maturing boys had lower vertical jump scores but a substantial higher rate of development with age (3% per year). Performance tends to plateau during the first 3 years following the improvements in agility (9.1%, P<0.05). In the running tests, early maturers had better performances (19%, P<0.05), while a higher rate of improvement of 1% was observed for the late maturers. Young soccer players should be expected to have substantial improvements in short-term performance, influenced by independent variation between players in maturity status.

OBLA is a better predictor of performance than Dmax in long and middle-distance well-trained runners.

AIM: The main purpose of this study was to investigate if the lactate threshold estimated by the maximal deviation method (LTDmax) and the onset of blood lactate accumulation speed (LTOBLA) are good correlates of middle- and long-distance running performance in well-trained endurance runners. METHODS: Eleven long- and eleven middle-distance runners participated in this study. All participants completed a maximal incremental running test on a treadmill to determine maximal physiological variables and velocities corresponding to LTDmax and LTOBLA (4 mmol·L-1 of lactate concentration). The relationships between LTDmax, LTOBLA and the best 10-km (S10km) and 3-km (S3km) race pace were analyzed in the long- and middle distance runners, respectively. RESULTS: The velocities for LTDmax and LTOBLA were 17.0±0.7 km·h-1 and 17.5±1.3 km·h-1 for the long-distance runners and 16.9±1.1 km·h-1 and 17.4±1.3 km·h-1 for the middle-distance runners. A positive linear relationship was found between LTDmax and S10km (r=0.873, P<0.001), as well as between LTOBLA and S10km (r=0.919, P<0.001) in the long-distance runners. Similarly, LTDmax and LTOBLA were significantly correlated with S3km in the middle-distance runners (r=0.825, P<0.01 and r=0.849, P<0.001, respectively). CONCLUSION: These results indicate that both LTOBLA and LTDmax are highly associated to running performance according to S10km and S3km in well-trained long- and middle-distance runners. Thus, we conclude that competitive middle- and long-distance athletes may find these measures useful to monitor running performance within 3 weeks of laboratory testing.

Interaction effects of stride angle and strike pattern on running economy.

This study aimed to investigate the relationship between stride angle and running economy (RE) in athletes with different foot strike patterns. 30 male runners completed 4 min running stages on a treadmill at different velocities. During the test, biomechanical variables such as stride angle, swing time, contact time, stride length and frequency were recorded using an optical measurement system. Their foot strike pattern was determined, and VO2 at velocities below the lactate threshold were measured to calculate RE. Midfoot/forefoot strikers had better RE than rearfoot strikers (201.5±5.6 ml · kg(-1) · km(-1) vs. 213.5±4.2 ml · kg(-1) · km(-1)respectively; p=0.019). Additionally, midfoot/fore-foot strikers presented higher stride angles than rearfoot strikers (p=0.043). Linear modelling analysis showed that stride angle is closely related to RE (r=0.62, p<0.001) and that the effect of stride angle on RE was different in the 2 groups. From an arbitrary value of 4°, a rearfoot strike pattern is likely to be more economical, whereas at any lower degree, the midfoot/forefoot strike pattern appears to be more desirable. A biomechanical running technique characterised by high stride angles and a midfoot/forefoot strike pattern is advantageous for a better RE. Athletes may find stride angle useful for improving RE.

Greater performance impairment of black runners than white runners when running in hypoxia.

This study aimed to compare the response of performance-matched black and white runners during maximal and sub-maximal running in normoxic and hypoxic conditions. 14 well-trained runners (8 black, 6 white) performed 2 incremental maximal exercise tests and 2 fatigue resistance tests at 21% O2 (normoxia) or 14% O2 (hypoxia). Respiratory parameters, heart rate (HR), lactate concentration ([La(-)]) as well as arterial saturation (SpO2) were measured. Enzyme activities and myosin heavy chain content (MHC) were also measured. White runners reached a significantly greater peak treadmill speed and a higher HRmax than black runners in hypoxia (p<0.05). Additionally, White runners achieved a greater time to fatigue than black runners (p<0.05), with black runners displaying a greater decline in performance in hypoxia compared to normoxia (20.3% vs. 13.4%, black vs. white, respectively). However, black runners presented lower [La(-)] and higher SpO2 than white runners in hypoxia (p<0.05). Black runners had a higher proportion of MHC IIa and higher lactate dehydrogenase activity (p<0.05). The greater performance impairment observed in black runners in hypoxia suggests a greater performance sensitivity to this condition, despite the maintenance of physiological variables such as SpO2 and [La (-) ] within a smaller range than white runners.

Differences in ground contact time explain the less efficient running economy in north african runners.

The purpose of this study was to investigate the relationship between biomechanical variables and running economy in North African and European runners. Eight North African and 13 European male runners of the same athletic level ran 4-minute stages on a treadmill at varying set velocities. During the test, biomechanical variables such as ground contact time, swing time, stride length, stride frequency, stride angle and the different sub-phases of ground contact were recorded using an optical measurement system. Additionally, oxygen uptake was measured to calculate running economy. The European runners were more economical than the North African runners at 19.5 km · h(-1), presented lower ground contact time at 18 km · h(-1) and 19.5 km · h(-1) and experienced later propulsion sub-phase at 10.5 km · h(-1),12 km · h(-1), 15 km · h(-1), 16.5 km · h(-1) and 19.5 km · h(-1) than the European runners (P < 0.05). Running economy at 19.5 km · h(-1) was negatively correlated with swing time (r = -0.53) and stride angle (r = -0.52), whereas it was positively correlated with ground contact time (r = 0.53). Within the constraints of extrapolating these findings, the less efficient running economy in North African runners may imply that their outstanding performance at international athletic events appears not to be linked to running efficiency. Further, the differences in metabolic demand seem to be associated with differing biomechanical characteristics during ground contact, including longer contact times.