Effect of unaware clock manipulation on pacing strategy and performance in recreational athletes

It is unclear how athletes regulate their performance prior and during exercise when deceptive methods are applied. Therefore, the aim of this study was to test if time manipulation can influence pacing strategy and running performance. Ten recreationally active subjects were informed they would complete four 60-min time trials only with time feedback. The first session was a familiarization trial (60-min), and in the following three sessions, the time feedback was modified: normal chronometer (NC—60 min.), 10% faster (Faster chronometer—FC—54 min.), and 10% slower (slower chronometer—SC—66 min.). Total distance was different between conditions, while average of total speed, Heart Rate, oxygen consumption, and Rate of Perceived Exertion were similar (p > 0.05). A slow start pacing strategy was adopted in all conditions and did not differ between conditions when averaged across the session; however, when analyzing the first and final 10 min of the session, differences were found between conditions. Finally, the observed time was an important determinant of the regulation of exercise intensity, because, although the pacing strategy adopted in all conditions was regulated according to previous exercise information, adjustments were made in the initial (NC) and final (FC) phases of the trials

Effects of Sprint versus High-Intensity Aerobic Interval Training on Cross-Country Mountain Biking Performance: A Randomized Controlled Trial.

OBJECTIVES: The current study compared the effects of high-intensity aerobic training (HIT) and sprint interval training (SIT) on mountain biking (MTB) race simulation performance and physiological variables, including peak power output (PPO), lactate threshold (LT) and onset of blood lactate accumulation (OBLA). METHODS: Sixteen mountain bikers (mean ± SD: age 32.1 ± 6.4 yr, body mass 69.2 ± 5.3 kg and VO2max 63.4 ± 4.5 mL∙kg(-1)∙min(-1)) completed graded exercise and MTB performance tests before and after six weeks of training. The HIT (7-10 x [4-6 min--highest sustainable intensity / 4-6 min-CR100 10-15]) and SIT (8-12 x [30 s--all-out intensity / 4 min--CR100 10-15]) protocols were included in the participants' regular training programs three times per week. RESULTS: Post-training analysis showed no significant differences between training modalities (HIT vs. SIT) in body mass, PPO, LT or OBLA (p = 0.30 to 0.94). The Cohen's d effect size (ES) showed trivial to small effects on group factor (p = 0.00 to 0.56). The interaction between MTB race time and training modality was almost significant (p = 0.08), with a smaller ES in HIT vs. SIT training (ES = -0.43). A time main effect (pre- vs. post-phases) was observed in MTB race performance and in several physiological variables (p = 0.001 to 0.046). Co-variance analysis revealed that the HIT (p = 0.043) group had significantly better MTB race performance measures than the SIT group. Furthermore, magnitude-based inferences showed HIT to be of likely greater benefit (83.5%) with a lower probability of harmful effects (0.8%) compared to SIT. CONCLUSION: The results of the current study suggest that six weeks of either HIT or SIT may be effective at increasing MTB race performance; however, HIT may be a preferable strategy. TRIAL REGISTRATION: ClinicalTrials.gov NCT01944865

Modelo de predição de uma repetição máxima (1RM) baseado nas características antropométricas de homens e mulheres Modelo de predicción de una repetición máxima (1RM) basado en las características antropométricas de hombres y mujeres Prediction model of a maximal repetition (1RM) based on male and female anthropometrical characteristics

O objetivo do presente estudo foi desenvolver uma equação para predição da carga de uma repetição máxima (1RM) em homens e mulheres, usando exclusivamente as características antropométricas. Participaram deste estudo 44 jovens de baixo risco, com experiência em treinamento de força, sendo 22 do sexo masculino (23 &plusmn; 4 anos, 76,6 &plusmn; 12,7kg, 173,9 &plusmn; 5,5cm, 11 &plusmn; 4,5% de gordura) e 22 do feminino (22 &plusmn; 4 anos, 54 &plusmn; 6,0kg, 161 &plusmn; 5,8cm, 18 &plusmn; 2,2% de gordura). Inicialmente, eles passaram por uma avaliação antropométrica seguida de um teste de 1RM de familiarização no exercício de desenvolvimento, que foi repetido após 48h. A repetibilidade do teste de 1RM foi testada pelo Wilcoxon matched paired test. Finalmente, a carga de 1RM foi modelada em função das variáveis antropométricas por regressão linear múltipla (forward stepwise) usando como critério de corte das variáveis independentes deltar² < 0,01. A confiabilidade dos modelos foi expressa pela análise de Bland e Altman. Adotou-se em todos os testes alfa = 0,05. Não se registraram diferenças entre teste e reteste, resultando em 44,6 &plusmn; 13,2kg e 12,2 &plusmn; 3,2kg nos indivíduos do sexo masculino (SM) e feminino (SF), respectivamente. Além das variáveis antropométricas, incluiu-se aos modelos o tempo de experiência em treinamento de força. No SM, o modelo resultou em 84% da variância explicada, com erro padrão equivalente a 12%. Por outro lado, no SF, a capacidade preditiva do modelo obtido foi mais fraca, resultando em 56% da variância explicada e erro padrão equivalente a 20%. Em conclusão, os modelos obtidos mostraram adequada confiabilidade, de forma que podem ser utilizados como ferramentas para predição da carga de 1RM.<br>El objetivo del presente estudio ha sido desarrollar una ecuación para predecir la carga de una repetición máxima (1RM) en hombres y mujeres, usando exclusivamente las características antropométricas. Participaron de este estudio 44 jóvenes de bajo riesgo, con experiencia en entrenamiento de fuerza, 22 del sexo masculino (23 &plusmn; 4 años, 76,6 &plusmn; 12,7 kg, 173,9 &plusmn; 5,5 cm, 11 &plusmn; 4,5% de grasa) y 22 del sexo femenino (22 &plusmn; 4 años, 54 &plusmn; 6,0 kg, 161 &plusmn; 5,8 cm, 18 &plusmn; 2,2% de grasa). Al inicio, estos pasaron por una evaluación antropométrica seguida de un test de 1RM de familiarización en el ejercicio en desarrollo, que fue repetido después de 48 h. La repetibilidad del test de 1RM fue probada por Wilcoxon matched paired test. Finalmente la carga de 1RM fue modelada en función de las variables antropométricas por regresión lineal múltiple (forward stepwise) usando como criterio de aglomeración de las variables independientes deltar² < 0,01. La confiabilidad de los modelos se expresó por el análisis de Bland y Altman. En todos los tests se adoptó alfa = 0,05. No se registraron diferencias entre el test y el retest, resultando en 44,6 &plusmn; 13,2 kg y 12,2 &plusmn; 3,2kg en los individuos del sexo masculino (SM) y femenino (SF), respectivamente. Fuera de las variables antropométricas, se incluyó a los modelos el tiempo de experiencia en la actividad de fuerza. En el SM, el modelo resultó en 84% de la varianza explicada, con un error padrón equivalente a 12%. Por otro lado, en el SF, la capacidad predictiva del modelo obtenido no fue tan eficaz, resultando en 56% de la varianza explicada y un error padrón equivalente a 20%. En conclusión, los modelos obtenidos mostraron adecuada confiabilidad, de forma que pueden ser utilizados como herramientas para predecir la carga de 1RM.<br>The goal of the present study was to develop an equation for predicting the workload of one maximal repetition (1RM) in women and men, based exclusively on anthropometrical characteristics. Forty-four low-risk and experienced in strength training young subjects, being 22 male (23 &plusmn; 4 years, 76.6 &plusmn; 12.7 kg, 173.9 &plusmn; 5.5 cm, 11 &plusmn; 4.5 % of body fat) and 22 female (22 &plusmn; 4 years, 54 &plusmn; 6.0 kg, 161 &plusmn; 5.8 cm, 18 &plusmn; 2.2 % of body fat) volunteered for this study. All subjects were submitted to an anthropometrical evaluation followed by a 1RM familiarization test (shoulder press), which was repeated after 48h. The repeatability was tested using Wilcoxon Matched paired test. Finally, the 1RM workload was modeled in relation to the anthropometrical variables through multiple linear regression (forward stepwise) using as cutoff criteria for the independent variables deltar² < 0.01. The models reliability was expressed by the Bland and Altman analysis. All tests assumed alpha = 0.05. No significant differences were recorded between the two tests, resulting 44.6 &plusmn; 13.2 kg and 12.2 &plusmn; 3.2kg, for male (MS) and female (FS) subjects respectively. The time of practice in strength training was also included in the models. The model resulted in 84% of explained variance and a standard error of 12% for the MS. On the other hand, for the FS the predictive capacity was weaker than for = the MS, resulting in 56% of the explained variance and a standard error of 20%. In conclusion, the obtained models showed acceptable reliability so that they can be currently used as a tool for predicting the 1RM workload