Martin Mooses

Dissociation between running economy and running performance in elite Kenyan distance runners

Abstract The purpose of this study was to investigate the relationship between running economy (RE) and performance in a homogenous group of competitive Kenyan distance runners. Maximal aerobic capacity (VO2max) (68.8 ± 3.8 ml∙kg−1∙min−1) was determined on a motorised treadmill in 32 Kenyan (25.3 ± 5.0 years; IAAF performance score: 993 ± 77 p) distance runners. Leg anthropometry was assessed and moment arm of the Achilles tendon determined. While Achilles moment arm was associated with better RE (r2 = 0.30, P = 0.003) and upper leg length, total leg length and total leg length to body height ratio were correlated with running performance (r = 0.42, P = 0.025; r = 0.40, P = 0.030 and r = 0.38, P = 0.043, respectively), RE and maximal time on treadmill (tmax) were not associated with running performance (r = −0.01, P = 0.965; r = 0.27; P = 0.189, respectively) in competitive Kenyan distance runners. The dissociation between RE and running performance in this homogenous group of runners would suggest that RE can be compensated by other factors to maintain high performance levels and is in line with the idea that RE is only one of many factors explaining elite running performance.

Better economy in field running than on the treadmill: evidence from high-level distance runners

Given the ongoing interest in ways to improve the specificity of testing elite athletes in their natural environment, portable metabolic systems provide an opportunity to assess metabolic demand of exercise in sport-specific settings. Running economy (RE) and maximal oxygen uptake (V.O2max) were compared between track and treadmill (1% inclination) conditions in competitive level European distance runners who were fully habituated to treadmill running (n = 13). All runners performed an exercise test on running track and on treadmill. While V.O2max was similar on the track and on the treadmill (68.5 ± 5.3 vs. 71.4 ± 6.4 ml·kg−1·min−1, p = 0.105, respectively), superior RE was found on the track compared to the treadmill (215.4 ± 12.4 vs. 236.8 ± 18.0 O2 ml·kg−1·km−1, p < 0.001). RE on the track was strongly correlated with RE on the treadmill (r = 0.719, p = 0.006). The present findings indicate that high-level distance runners have significantly better RE but not V.O2max on the track compared to treadmill. This difference may be due to biomechanical adjustments. As RE is strongly correlated between the two conditions, it would be reasonable to assume that interventions affecting RE on the treadmill will also affect RE on the track.

Different Methods Yielded Two-Fold Difference in Compliance with Physical Activity Guidelines on School Days.

Introduction The aim was to compare the average and the days method in exploring the compliance of children with physical activity guidelines and describe their physical activity patterns in different school day segments. Methods Physical activity was objectively measured in 472 children aged 6–13 for one school week. Children were compliant when fulfilling PA recommendations 1) on average over all measured days (average method) or 2) on at least four measured days (days method). To explore the difference in moderate to vigorous physical activity (MVPA) minutes between compliant and non-complaint children (using both the average and days method) in various day segments, linear mixed models was used. Results Compliance with physical activity guidelines was significantly higher with the average compared to the days method (51.7% and 23.7%, respectively). In segmented-day analysis, compliant children accrued more MVPA minutes in all day segments, especially during after-school. Gender differences appeared only during the in-school segments, where girls spent less time in MVPA (average method: -4.39 min, 95% CI = -5.36,-3.42, days method: -4.45 min, 95%CI = -5.46,-3.44). Older children accrued more MVPA minutes during physical education classes, but less during breaks, compared to younger children. Conclusions The used methods yielded remarkably different prevalence estimates for compliance to physical activity recommendations. To ensure comparability between studies, interventions and reports, there is a need for internationally agreed operationalization and assessment methods of physical activity guidelines. As non-compliant children had lower MVPA during all day segments, greater efforts should be made to provide physical activity opportunities both during and after school.

Letter to the Editor (Comment on dissociation between running economy and running performance in elite Kenyan distance runners)

Abstract Santos-Concejero and Tucker argued in their letter to the editor that in our study the running economy in achieving superior performance was overlooked due to some methodological aspects. Having given the remarks of Santos-Concejero and Tucker appropriate consideration, in this letter to the editor, we argue that our paper does not downplay the influence of running economy on the determinants of the East African running phenomenon, but rather adds novel insights into the interaction between running economy, maximal oxygen uptake and performance.

Spinal posture in different DanceSport dance styles compared with track and field athletes.

BACKGROUND AND OBJECTIVE In DanceSport, athletes train for many years to develop a very specific posture. Presently there are few data as to whether these adaptations are habitual or cause permanent anatomical changes to the spine. The aim of the current study was to evaluate lumbar lordosis and thoracic kyphosis of the international level DanceSport dancers using track and field athletes as controls. MATERIALS AND METHODS Thirty competitive DanceSport couples (15 men aged 23.4±6.6 years; 15 women aged 22.5±6.4 years) and 29 track and field athletes (16 mean aged 27±4.4 years and 13 women aged 22±4.1 years) volunteered. Twelve couples were Standard, 7 Latin American and 11 were Ten Dance couples. Thoracic kyphosis and lumbar lordosis angle were assessed in lateral view using a Vertebral Fracture Assessment scan. RESULTS DanceSport athletes had smaller S-shaped vertebral curvatures compared to track and field athletes. Male (5.7±4.7°) and female dancers (8.7±5.9°) had significantly smaller lumbar lordosis angle compared to their track and field counterparts (22.3±9.9° for men; 20.3±5.9° for women). Female dancers (25.3±8.0°) also demonstrated significantly smaller thoracic kyphosis angle than female track and field (32.1±8.9°) participants. It was further revealed that female Latin American dancers had significantly smaller lumbar lordosis values (3.7±3.1°) compared with female Standard (10.7±6.1°) and Ten Dance dancers (9.7±5.5°). CONCLUSIONS The results of the present study suggest that smaller S-shaped vertebral curvatures of DanceSport athletes compared with track and field athletes are permanent changes rather than habitual.

Impact of sodium citrate ingestion during recovery after dehydrating exercise on rehydration and subsequent 40-km cycling time-trial performance in the heat

The purpose of this study was to assess the impact of sodium citrate (CIT) ingestion (600 mg·kg-1) during recovery from dehydrating cycling exercise (DE) on subsequent 40-km cycling performance in a warm environment (32 °C). Twenty male nonheat-acclimated endurance athletes exercised in the heat until 4% body mass (BM) loss occurred. After 16 h recovery with consumption of water ad libitum and prescribed diet (evening meal 20 kcal·kg-1, breakfast 12 kcal·kg-1) supplemented in a double-blind, randomized, crossover manner with CIT or placebo (PLC), they performed 40-km time-trial (TT) on a cycle ergometer in a warm environment. During recovery greater increases in BM and plasma volume (PV) concomitant with greater water intake and retention occurred in the CIT trial compared with the PLC trial (p < 0.0001). During TT there was greater water intake and smaller BM loss in the CIT trial than in the PLC trial (p < 0.05) with no between-trial differences (p > 0.05) in sweat loss, PV decrement, ratings of perceived exertion, or TT time (CIT 68.10 ± 3.28 min, PLC 68.11 ± 2.87 min). At the end of TT blood lactate concentration was higher (7.58 ± 2.44 mmol·L-1 vs 5.58 ± 1.32 mmol·L-1; p = 0.0002) and rectal temperature lower (39.54 ± 0.50 °C vs 39.65 ± 0.52 °C; p = 0.033) in the CIT trial than in the PLC trial. Compared with pre-DE time point, PV had decreased to a lower level in the PLC trial than in the CIT trial (p = 0.0001). In conclusion, CIT enhances rehydration after exercise-induced dehydration but has no impact on subsequent 40-km cycling TT performance in a warm uncompensable environment.

Lower Leg Length is Associated with Running Economy in High Level Caucasian Distance Runners

Abstract The aim of the present study was to investigate lower limb anthropometric and composition variables related to running economy (RE) and running performance in a homogeneous group of high level European distance runners. RE at the speeds of 14, 16 and 18 km·h−1 (189 ± 12; 188 ± 11; 187 ± 11 O2 ml·kg−1·km−1) and maximal oxygen uptake (VO2max) (67.3 ± 2.9 ml·kg−1·min−1) of 13 high level distance runners were determined on a motorised treadmill. Anthropometric variables and body composition were measured. The BMI was related to RE at the speed of 14 (r2 = 0.434; p = 0.014), 16 (r2 = 0.436; p = 0.014) and 18 km·h−1 (r2 = 0.389; p = 0.023). Lower leg length was negatively related to RE at the speed of 16 and showed such a tendency at the speed of 14 and 18 km·h−1. VO2max indicated a moderate relationship with RE at the speeds of 14, 16 and 18 km·h−1 (r2 = 0.372, p = 0.030; r2 = 0.350, p = 0.033; r2 = 0.376, p = 0.026, respectively) which was confirmed by subsequent partial correlation analysis. While lower leg length and the BMI presented a relationship with RE, none of the calculated body composition and anthropometric proportions were related to RE or performance. The relationship between RE and VO2max would confirm the notion that RE could be at least partly compensated by VO2max to achieve high performance results.