Training at moderate altitude improves submaximal but not maximal performance-related parameters in elite rowers.

Maximal oxygen consumption (V̇O2max), physiological thresholds, and hemoglobin mass are strong predictors of endurance performance. High values of V̇O2max, maximal aerobic power (MAP), and power output at anaerobic thresholds are key variables in elite rowers. Endurance athletes often use altitude training as a strategy to improve performance. However, no clear evidence exists that training at natural altitude enhances sea-level performance in elite rowers. This study aimed to evaluate the effect of altitude training on rowing-performance parameters at sea level. The study was conducted on eleven rowers (Six females, five males) from the Chilean National Team during a 3-week moderate altitude training (∼2,900 m. a.s.l.) under the live high-train high (LHTH) model. It included a rowing ergometer maximal incremental test and blood analysis (pre and post-altitude). Gas exchange analysis was performed to measure V̇O2max, ventilatory thresholds (VTs) and rowing economy/efficiency (ECR/GE%). LHTL training improves performance-related variables at sea level (V̇Emax: 3.3% (95% CI, 1.2-5.5); hemoglobin concentration ([Hb]): 4.3% (95% CI, 1.7-6.9); hematocrit (%): 4.5% (95% CI, 0.9-8.2); RBC (red blood cells) count: 5.3% (95% CI, 2.3-8.2); power at VT2: 6.9% (95% CI, 1.7-12.1), V̇EVT2: 6.4% (95% CI, 0.4-12.4); power at VT1: 7.3% (95% CI, 1.3-13.3), V̇EVT1: 8.7% (95% CI, 1.6-15.8)) and economy/efficiency-related variables (ECRVT2: 5.3% (95% CI, -0.6 to -10.0); GE(%): 5.8% (95% CI, 0.8-10.7)). The LHTH training decreased breathing economy at MAP (-2.8% (95% CI, 0.1-5.6)), pVT2 (-9.3% (95% CI, -5.9 to -12.7)), and pVT1 (-9.3% (95% CI, -4.1 to -14.4)). Non-significant changes were found for V̇O2max and MAP. This study describes the effects of a 3-week moderate altitude (LHTH training) on performance and economy/efficiency-related variables in elite rowers, suggesting that it is an excellent option to induce positive adaptations related to endurance performance.

Validation of a novel equation to predict lower-limb muscle mass in young soccer players: a brief communication / Validación de una nueva ecuación para predecir la masa muscular de los miembros inferiores en jugadores jóvenes de fútbol: una comunicación breve

Lower-limbs appendicular muscle mass is a key body composition trait related to health and performance. Considering the relevance of lower-limbs appendicular muscle mass in soccer players, the assessment and monitoring of this variable with a low-cost tool would be of great value in order to improve performance through training and nutritional interventions. This study aimed to develop a multiple regression model in order to validate, through dual-energy X-ray absorptiometry, a novel equation to predict lower-limbs appendicular muscle mass in young soccer players using anthropometric variables. Forty-two soccer players of the Chilean National Team (age, 17.1±1.3 years; body mass, 70.0±6.8 kg; height, 175.0±6.6 cm) underwent anthropometrically and body composition assessments. Forward stepwise linear regression was used to develop the equation to estimate the lower-limb appendicular muscle mass. The estimated results were compared with measurements by dual-energy X-ray absorptiometry. The best predictor model to estimate lower-limbs appendicular muscle mass was (kg): (-21.268 + (0.087*height) - (0.853*middle thigh circumference) - (0.329*middle thigh skinfold) + (1.136*corrected middle thigh circumference) + (0.306*calf circumference)) (R2= 0.83). The lower-limbs appendicular muscle mass estimated by the equation and measured by DXA were similar (14.71±1.72 kg vs 14.76±1.89 kg, respectively), and have a good concordance according to Bland-Altman method (mean difference: 0.049 kg; 95 % IC: -1.481 to 1.578 kg) and Lin's concordance correlation coefficient (0.91; 95 % CI: 0.85 - 0.96) methods. In conclusion, the predictive equation is a valid, easy to calculate, and a low-cost tool to predict lower-limbs appendicular muscle mass in young soccer players.

La masa muscular de los miembros inferiores es un factor antropométrico clave relacionado a la salud y el rendimiento deportivo. Considerando la relevancia de este factor en jugadores de fútbol, la medición y monitoreo de esta variable a través de herramientas prácticas de bajo costo puede ser de gran utilidad para lograr objetivos relacionados a mejorar el rendimiento a través del entrenamiento e intervenciones nutricionales. El objetivo de este estudio fue desarrollar un modelo de regresión lineal con el objetivo de validar una nueva ecuación predictiva de la masa muscular de miembros inferiores en jugadores jóvenes de fútbol. Cuarenta y dos jugadores jóvenes de fútbol pertenecientes a la Selección Nacional Chilena (17,1±1,3 años; 70,0±6,8 kg; 175,0±6,6 cm) fueron sometidos a evaluaciones antropométricas y de composición corporal. La regresión lineal de pasos hacia adelante fue utilizada para desarrollar la ecuación para estimar la masa muscular de miembros inferiores. Los resultados estimados fueron comparados con medición de absorciometría de rayos X de doble energía (DEXA). El mejor modelo predictor de masa muscular de miembros inferiores (kg) fue: (-21,268 + (0,087*talla) - (0,853*circunferencia de muslo medio) - (0,329*pliegue de muslo medio) + (1,136*circunferencia de muslo medio corregida) + (0,306*circunferencia de pantorrilla)) (R2= 0,83). La masa muscular estimada por la ecuación y la medida por DEXA fue similar (14,71±1,72 kg vs 14,76±1,89 kg, respectivamente), y tuvo una buena concordancia acorde al método Bland-Altman (diferencia promedio: 0,049 kg; 95 % IC: -1,481 to 1,578 kg) y el coeficiente de correlación de concordancia de Lin (0,91; 95 % CI: 0,85 - 0,96). En conclusión, la ecuación predictiva desarrollada en este estudio es una herramienta válida, fácil de calcular y de bajo costo que permite estimar la masa muscular de miembros inferiores en futbolistas jóvenes.

Analysis of Agreement Between 4 Lactate Threshold Measurements Methods in Professional Soccer Players.

Cerda-Kohler, H, Burgos-Jara, C, Ramírez-Campillo, R, Valdés-Cerda, B, Báez, E, Zapata-Gómez, D, Cristóbal Andrade, D, and Izquierdo, M. Analysis of agreement between 4 lactate threshold measurements methods in professional soccer players. J Strength Cond Res 30(10): 2864-2870, 2016-Lactate threshold (LT) represents the inflection point of blood lactate values from rest to high-intensity exercise during an incremental test, is commonly used to determine exercise intensity, and is related to different positional roles of elite soccer players. Different methodologies have been adopted to determine the LT; however, the agreement between these methodologies in professional soccer players is unclear. Seventeen professional soccer players were recruited (age 24.7 ± 3.7 years, body mass 70.1 ± 5.3 kg, height 172.8 ± 7.3 cm) and performed an incremental treadmill test until volitional fatigue. Speed at LT (LTspeed), heart rate at LT (LTHR), and lactate values from capillary blood samples obtained at 3-minute intervals were analyzed using 4 LT measurement methods: visual inspection (VI), maximum distance (Dmax), modified Dmax (DmaxM), and logarithmic (log-log). Only Bland-Altman analysis for LTHR showed agreement between VI and Dmax, between VI and DmaxM, and between Dmax and DmaxM methods. No agreement between methods was observed after intraclass correlation coefficient and 95% one-sided lower-limit analysis. Comparative results showed that LTspeed was lower (p < 0.01) with the log-log method compared with the Dmax method and lower (p < 0.01) with the latter compared with the VI and DmaxM methods. Regarding LTHR, higher (p < 0.01) values were observed using the VI, DmaxM, and Dmax methods compared with the log-log method. Therefore, VI, Dmax, DmaxM, and log-log methods should not be used interchangeably for LT measurement. More studies are needed to determine a gold standard for LT detection in professional soccer players.