Effects of a low-carbohydrate diet on performance and body composition in trained cyclists

Introduction: Previous evidence suggests that low-carbohydrate diets may improve body composition and performance relative to body weight in endurance athletes. This has been the first study that has attempted to evaluate the utility of low-carbohydrate diets in a sample of eleven trained and experienced road cyclists who consumed 10% of their caloric intake in the form of carbohydrates during four weeks while maintaining a neutral energy balance (50 kcal/kg/day). Body composition was evaluated through an electrical impedance assessment before and after the intervention while maximal power output (5 and 20 min) was measured on a bike trainer by following a standardized protocol and in the same room conditions for all the participants. The study was performed during the preseason, when the subjects could abstain from performing high-intensity workouts. The participants, eleven men aged 31 ± 5 years, performed four weekly 150 min training sessions at submaximal intensities and received nutritional support from a certified sport nutritionist. The intervention resulted in reduced total weight (-2.51 kg) and body fat percentage (2.42%), and improved relative power (+0.2 w/kg for 20 min and +0.25 w/kg for 5 min) values while absolute power remained unchanged. The results suggest that low-carbohydrate diets could be used in order to induce changes in body composition and improve relative power during the preseason. However, future research with larger sample sizes and a control group is needed in order to validate the results.Introducción: La evidencia científica previa sugiere que las dietas bajas en hidratos de carbono pueden mejorar la composición corporal y el rendimiento relativo al peso en deportistas de resistencia. Este ha sido el primer estudio que ha intentado evaluar la utilidad de este tipo de dieta en una muestra de once ciclistas de carretera entrenados y experimentados que consumieron un 10% de sus calorías diarias en forma de hidratos de carbono durante cuatro semanas mientras mantenían un balance energético neutro (50 kcal/kg/día). La composición corporal se evaluó con bioimpedancia eléctrica antes y después de la intervención mientras que la potencia máxima (5 y 20 min) se evaluó siguiendo un protocolo estandarizado sobre un rodillo de ciclismo en las mismas condiciones ambientales para todos los participantes. El estudio se realizó en la pretemporada, cuando todos los sujetos podían abstenerse de realizar entrenamientos de alta intensidad. Los participantes, once hombres con edades de 31 ± 5 años, realizaron cuatro sesiones de entrenamiento de 150 minutos de duración semanales y recibieron apoyo de un nutricionista deportivo titulado. La intervención resultó en una disminución del peso (-2, 51 kg) y el porcentaje de grasa corporal (-2, 42%), así como en un aumento de la potencia relativa (+0, 2 w/kg en potencia 20 min y +0, 25 w/kg en potencia 5 min) mientras que los valores de potencia absoluta no se modificaron. Los resultados sugieren que las dietas bajas en hidratos de carbono podrían utilizarse durante la pretemporada para inducir cambios en la composición corporal y mejorar la potencia relativa. Sin embargo, hacen falta estudios con una muestra más grande y un grupo de control para poder validar estos resultados

Efectos del alpinismo de altitud en la composición corporal: revisión sistemática

High altitude mountaineering is characterized by high energetic requirements due to the environment in which the activity is developed: negative energy balance, extreme cold, high altitude and the assumption of potential risks can be found during the practice of this sport. High altitude mountaineering, as a result of the previous factors, induces changes in body composition which have never been studied previously in a systematic review. A search within four different databases (PubMed, SportDiscus, Scopus and Medline) was performed using the thesaurus terms “Mountaineering” and “Body composition”. A second search was performed using the following terms “Altitude” and “Body composition”. The selection criteria included studies with healthy adults which evaluated the effects of at least 14 days of uninterrupted stays at altitudes above 4,000 m. The studies included in the review assessed body composition through different methods such as anthropometry, bioimpedance, dual energy x-ray absorptiometry, hydrostatic weighing and air displacement plethysmography. The search was performed up to and including December 1st 2018. Eleven observational studies met the inclusion criteria. All studies reported weight loss, of which five reported significant reductions in lean mass and six reported reductions in fat mass. Also, three studies reported reductions in both fat mass and lean mass. Current evidence is limited to observational studies with important confounding factors affecting the final conclusions. Longitudinal studies with a better methodological design and control groups are needed in order to verify these results.El alpinismo a grandes altitudes se caracteriza por elevados requerimientos energéticos debido al ambiente en el que se desarrolla la actividad: los balances energéticos negativos, el frío extremo, la exposición a la altitud o niveles de estrés elevados se pueden observar en la práctica de este deporte. Debido a estos factores, el alpinismo de altitud induce cambios en la composición corporal que no se han estudiado previamente en una revisión sistemática. Se realizó una búsqueda en cuatro bases de datos (PubMed, SportDiscus, Scopus and Medline) con los términos Mesh “Mountaineering” y “Body composition”. Una segunda búsqueda se realizó usando los términos “Altitude” y “Body composition”. Los criterios de selección incluyeron estudios con adultos sanos que evaluaron los efectos de estancias de al menos 14 días ininterrumpidos en altitudes superiores a los 4.000 m. La composición corporal se analizó con diferentes métodos como antropometría, bioimpedancia, absorciometría dual de rayos x, pesada hidrostática y pletismografía por desplazamiento de aire. La búsqueda se realizó incluyendo estudios fechados hasta el 1 de diciembre de 2018. Once estudios observacionales cumplieron con los criterios de inclusión. Todos los estudios reportaron pérdida de peso, de los cuales cinco reportaron reducciones en masa magra; seis, reducciones en masa grasa; y tres, reducciones en ambas. La evidencia actual se limita a estudios observacionales con factores de confusión importantes que afectan a los resultados finales. Se necesitan estudios longitudinales con mejor diseño metodológico y grupo control para verificar estos resultados

Time to exhaustion at estimated functional threshold power in road cyclists of different performance levels

This study assessed the functional threshold power and the time to exhaustion estimated from the Allen & Coggan test and verify whether performance level has an influence on this parameter

768-km Multi-Stage Ultra-Trail Case Study-Muscle Damage, Biochemical Alterations and Strength Loss on Lower Limbs

A series of case studies aimed to evaluate muscular fatigue in running a 768-km ultra-trail race in 11 days. Four non-professional athletes (four males) were enrolled. Muscle damage blood biomarkers (creatine kinase (CK), lactodeshydrogenase (LDH), aspartate transaminase (AST) and alanine aminotransferase (ALT) and lower limb strength were evaluated by using Bosco jumps test; squat jump (SJ), countermovement jump (CMJ) and Abalakov jump (ABA) were assessed before (pre), after the race (post) and for two and nine days during the recovery period (rec2 and rec9), respectively. Results showed: pre-post SJ = −28%, CMJ = −36% and ABA = −21%. Values returned to basal during rec9: SJ = −1%, CMJ = −2% or even exceeded pre-values ABA = +3%. On the contrary, muscle damage blood biomarkers values increased at post; CK = +888%, LDH = +172%, AST = +167% and ALT = +159% and the values returned gradually to baseline at rec9 except for AST = +226% and ALT = +103% which remained higher. Nonparametric bivariate Spearman’s test showed strong correlations (Rs ≥ 0.8) between some jumps and muscle damage biomarkers at post (SJ-LDH Rs = 0.80, SJ-AST Rs = 0.8, ABA-LD H Rs = 0.80 and ABA-AST Rs = 0.80), at rec2 (SJ-CK Rs = 0.80 and SJ-ALT Rs = 0.80) and even during rec9 (ABA-CK). Similarly, some parameters such as accumulated elevation and training volume showed a strong correlation with LDH values after finishing the ultra-trail race. The alteration induced by completing an ultra-trail event in the muscle affects lower limb strength and may in some circumstances result in serious medical conditions including post- exertional rhabdomyolysis

Characteristics of pedaling muscle stiffness among cyclists of different performance levels

Background and Objectives: The aim of the present study was to compare the impact of an incremental exercise test on muscle stiffness in the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), and gastrocnemius (GL) among road cyclists of three performance levels. Materials and Methods: The study group consisted of 35 cyclists grouped according to their performance level; elite (n = 10; professional license), sub-elite (n = 12; amateur license), and recreational (n = 13; cyclosportive license). Passive muscle stiffness was assessed using myometry before and after an incremental exercise test. Results: There was a significant correlation between time and category in the vastus lateralis with stiffness increases in the sub-elite (p = 0.001, Cohen’s d = 0.88) and elite groups (p = 0.003, Cohen’s d = 0.72), but not in the recreational group (p = 0.085). Stiffness increased over time in the knee extensors (RF, p < 0.001; VL, p < 0.001), but no changes were observed in the knee flexors (GL, p = 0.63, BF, p = 0.052). There were no baseline differences among the categories in any muscle. Conclusions: Although the performance level affected VL stiffness after an incremental exercise test, no differences in passive stiffness were observed among the main muscles implicated in pedaling in a resting state. Future research should assess whether this marker could be used to differentiate cyclists of varying fitness levels and its potential applicability for the monitoring of training load. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Anthropometric Characteristics of Road Cyclists of Different Performance Levels

Road cycling is an endurance sport characterized by several anthropometric performance factors, such as reduced body mass and body fat percentage. As the power to weight ratio is considered one of the most important markers of performance in this sport discipline, it is speculated that anthropometric factors could relate to the physiological parameters found in road cyclists of different performance levels. The current study aimed to describe the anthropometric differences across road cyclists of different performance levels and to assess whether anthropometric values could relate to physiological markers that are commonly used to classify road cyclists, according to their performance level. We classified 46 cyclists as recreationally trained, trained, well trained and professional, according to their VO2max, and performed graded exercise tests and complete anthropometric assessments. The results showed that there were no significant anthropometric differences between trained, well trained and professional cyclists, with only recreationally trained cyclists exhibiting larger perimeters and skinfolds than professional cyclists. Further, although physiological performance, such as VO2max and respiratory compensation point, correlated negatively with several skinfolds and perimeters, these correlations remained restrained and did not distinguish between cyclists of different specialties

Niveles de ansiedad precompetitiva en ciclistas profesionales

El ciclismo de carretera es un deporte con un gran seguimiento y un impacto económico importante. Los ciclistas profesionales se ven sometidos a una gran presión por conseguir resultados para prolongar sus contratos y aumentar sus ganancias. Por otra parte, las pruebas cicloturistas como la Quebrantahuesos pueden llegar a ser extremadamente competitivas y conllevar unos niveles importantes de ansiedad en los participantes. En este estudio se ha comprobado, mediante el uso de un cuestionario validado, que los ciclistas profesionales sufren unos niveles de ansiedad precompetitiva superiores a los vistos en los participantes en las pruebas cicloturistas comúnmente disputadas como la Quebrantahueso

Los escaladores de alto nivel sufren mayor ansiedad precompetitiva que los escaladores aficionados

La escalada deportiva es un deporte con escaso arraigo competitivo: los premios otorgados son de escaso valor, la popularidad del deporte es relativamente baja y apenas una franja de todos los practicantes compite en esta disciplina deportiva. En el presente estudio comprobamos, mediante un cuestionario validado, que a pesar de todo lo anterior, los escaladores de alto nivel presentan niveles de ansiedad más elevados que los escaladores aficionados durante las competiciones. Los resultados de este estudio pueden permitir elaborar estrategias para la prevención del exceso de ansiedad en escaladores de alto nivel