Virtual cycling effort is dependent on power update rate.

Cycling ergometer protocols are commonly integrated with a virtual reality environment (VRE), especially because of its static position that also allows multiple exercise experiments. Concerning VRE scenarios, visually delayed situations like the ones produced at excessive low update rates can also affect the sense of presence and physiological responses. However, the main interface between the subject and a cycling VRE is the power applied over the crank, and there are only a few experiments to evaluate the effect of delayed situations on this particular interface. Thus, this work aims to investigate the effects of the power update rate (PUR) over the subject`s performance on an avatar-based simulator during a drafting task. A custom cycling VRE was built, and 21 male recreational cyclists (175.9 ± 7.5 cm; 76.5 ± 13.9 kg) were tested at six different PUR levels from 100 to 3000 ms. As a result, PUR affects performance scores (virtual distance, efficiency, and heart rate, p < 0.01) at the given VRE conditions. The case-by-case analysis of the groups reveals that higher update rates always lead to a statistical equivalent or superior performance. Nevertheless, no parameter shows any group difference between 500 ms and lower PUR. These results suggest that virtual cycling protocols should consider PUR and other delay-related mechanisms as possible intervening factors over physiological responses and performance scores.

Influence of strength training intensity on subsequent recovery in elderly.

Understanding the influence of strength training intensity on subsequent recovery in elderly is important to avoid reductions in physical function during the days following training. Twenty-two elderly were randomized in two groups: G70 (65.9 ±â€¯4.8 years, n = 11) and G95 (66.9 ±â€¯5.1, n = 11). Baseline tests included maximum voluntary isometric contraction (peak torque and rate of torque development - RTD), countermovement jump, and functional capacity (timed up and go, stairs ascent and descent). Then, both groups performed a single strength training session with intensities of 70% (G70) or 95% (G95) of five repetition maximum. The same tests were repeated immediately, 24 h, 48 h, and 72 h after the session. Peak torque was lower than baseline immediately after for both groups and at 24 h for G95. Compared with G70, G95 had lower peak torque at 24 h and 48 h. Countermovement jump, timed up and go, stairs ascent, and RTD at 0-50 ms only differed from baseline immediately after for both groups. RTD at 0-200 ms was lower than baseline immediately after and 24 h after the session for both groups. In conclusion, reduced physical function immediately after strength training can last for 1-2 days in elderly depending on the type of physical function and intensity of training. Higher intensity resulted in greater impairment. Exercise prescription in elderly should take this into account, e.g., by gradually increasing intensity during the first months of strength training. These results have relevance for elderly who have to be fit for work or other activities in the days following strength training.

Desempenho e pacing na prova de 200m nado borboleta: variabilidade e relações dos tempos parciais de 50m com o tempo final / Rendimiento y ritmo en la carrera de 200m mariposa: variabilidad y relación del tiempo parcial de 50 metros con el tiempo final / Performance and pacing in 200m butterfly: variability and relations with the time 50 m parpartial and the final time

Objetivo. Analisar o desempenho e o pacing de prova dos semifinalistas da prova de 200m nado borboleta do 15.° Campeonato Mundial de Natação da Federação Internacional de Natação (FINA). Método. Os dados foram obtidos da página eletrônica da FINA. Os 32 tempos da etapa semifinal, masculina e feminina, foram divididos em 4 grupos: 8 homens classificados para a final (G1M), 8 homens não classificados (G2M), 8 mulheres classificadas para a final (G1F) e as 8 mulheres não classificadas (G2F). A velocidade de nado, para cada parcial de 50m, foi estimada pelo quociente entre 50m e o respectivo tempo. Foram calculados os coeficientes de variação de tempo das 4 parciais de 50m e comparados entre os grupos (ANOVA). Tamanho de efeito foi verificado com d de Cohen. Correlacionou‐se o desempenho (tempo total) com o tempo de cada parcial de 50m (r de Pearson). Resultados. O coeficiente de variação para as parciais de 50m foi menor nos grupos dos finalistas de ambos os sexos (G1M e G1F) e menor para as mulheres. A terceira parcial de 50m apresentou maior correlação com o desempenho final em ambos os sexos. A velocidade média caiu ao longo da prova em ambos os grupos. Conclusão. O pacing para o melhor desempenho na prova é evitar variações de tempo ao longo dos 200m nado borboleta e os treinamentos devem ser direcionados ao aprimoramento condicionante dessa parcial (150‐200m) (AU)

Objetivo. Analizar el desempeño y pacing durante la prueba de semifinalistas de 200m mariposa del 15.° Campeonato Mundial de Natación de la Federación Internacional de Natación (FINA). Método. Los datos fueron retirados de la página electrónica de la FINA. Los 32 tiempos de la semifinal masculina y femenina fueron divididos en cuatro grupos: ocho varones clasificados para el final de la prueba analizada (G1M), ocho varones no clasificados (G2M), ocho mujeres clasificadas (G1F) y ocho mujeres no clasificadas (G2F). La velocidad de nado para cada parcial de 50m fue estimada por el cociente entre 50m y su respectivo tiempo. Fueron calculados los coeficientes de variación del tiempo de los cuatro parciales de 50m y comparadas entre los grupos (ANOVA). Se observó el tamaño de efecto con d de Cohen. Se analizó la correlación entre el rendimiento (tiempo total) y el tiempo de cada parcial de 50m. Resultados. El coeficiente de variación para los parciales de 50m fue menor en los grupos finalistas de ambos sexos (G1M e G1F) y menor para las mujeres. El tercer parcial de 50m presentó mayor correlación con el rendimiento final en ambos sexos. La velocidad media disminuyó a lo largo de la prueba en ambos grupos. Conclusión. El ritmo para el mejor rendimiento en la prueba es evitar la variación del tiempo a lo largo de los 200m mariposa y el entrenamiento debe estar dirigido a la mejora de la condición física es ese parcial (150‐200m) (AU)

Objective. To analyze performance and pacing in 200m butterfly among the semifinalists in 15th FINA World Championship. Methods. Data were obtained from FINA website. Thirty two semifinals performances were divided in four groups: eight male classified (G1M), eight male unclassified (G2M), eight female classified (G1F), and eight female unclassified (G2F). Swimming velocity for each 50m partial was estimated by the quotient between distance and time. Coefficients of variation of the four 50m partials were compared among groups (ANOVA). Effects sizes were identified by the Cohen's d. Total time (performance) was correlated with each 50m partial time (Pearson's r). Results. Coefficients of variation were lower for the groups with best performance in both sexes (G1F and G1M) and in females. The third partial presented the larger correlation with overall performance. Average swimming velocity decreased along the event. Conclusion. The best pacing is to maintain swimming velocity constant within each 50m over the 200m and the training should be directed to the conditional improvement of this split (150‐200m) (AU)

Comparison of body adiposity index (BAI) and air displacement plethysmograph with estimations of % body fat in adults with Down's syndrome.

BACKGROUND/OBJECTIVES: The aim of this study was to verify the agreement between body fat percentage (%BF) values evaluated by air displacement plethysmograph (ADP) and body adiposity index (BAI) in adults with Down's syndrome (DS). SUBJECTS/METHODS: Forty-five adults with DS volunteered to participate in this study (19 women; age 28.7±8.5 years and 26 men; age 29.1±8.8 years). The %BF was measured by ADP (%BFADP) and estimated by anthropometric measures [%BF=(hip circumference/height)1.5-18] (%BFBAI). Agreement between methods was evaluated by paired t-test, Pearson's correlation coefficient and Bland-Altman analysis. RESULTS: Although high correlation coefficients were found between %BFADP and %BFBAI for women (r=0.78, P<0.05) and men (r=0.87, P<0.05), significant differences were observed between methods for both sexes (38.9±8.9 vs 42.5±8.5% for women, and 25.8±11.3 vs 32.6±5.4% for men in %BFADP and %BFBAI, respectively). Moreover, Bland-Altman analysis showed that the mean error estimate was +3.6 (95%CI, -7.59 to 14.79) in women and +6.74 (95%CI, -7.25 to 20.72) in men. CONCLUSIONS: The results indicate that BAI seems to be a limited method to evaluate %BF in women and in men with DS.

Effects of altering pedal frequency on the slow component of pulmonary VO2 kinetics and EMG activity.

This study investigated the effects of pedal frequency on the slow component of pulmonary oxygen uptake ( V O(2)) kinetics during heavy exercise at the same relative intensity. We hypothesized that higher pedal frequency (expected to enhance fast-twitch muscle fiber recruitment) would be associated with greater slow component amplitude (A' (s)), surface electromyography (normalized root mean square; RMS) and blood lactate concentration ([lactate]). Eight subjects performed square-wave transitions to heavy exercise at 35 and 115 rpm. Furthermore, alternated cadences square-wave transitions (35-115 rpm) were performed to examine the potential effects of additional fast-twitch muscle fiber recruitment on the slow component. Significance was accepted when P<0.05. The A' (s) was greater at higher cadences (0.58+/-0.08 and 0.70+/-0.09 L.min (-1) at 115 and 35-115 rpm, respectively) than at 35 rpm (0.35+/-0.04 L.min (-1)). Greater EMG increase over time (DeltaRMS ((10-3 min))) and [lactate] were observed at 115 and 35-115 rpm compared with 35 rpm. There was a significant correlation between A' (s) and overall DeltaRMS ((10-3 min)) for all pedal frequencies combined (r=0.63; P=0.001). Pedal frequency had no effect on time constants or time delays. These findings are consistent with the concept that progressive recruitment of muscle fibers is associated with the V O(2) slow component.

Cadence and workload effects on pedaling technique of well-trained cyclists.

This study investigated the effects of changing cadence and workload on pedaling technique. Eight cyclists were evaluated during an incremental maximal cycling and two 30-minute submaximal trials at 60% and 80% of maximal power output (W(60%) and W(80%), respectively). During submaximal 30-minute trials, they cycled for 10 minutes at a freely chosen cadence (FCC), 10 minutes at a cadence 20% above FCC (FCC+20%), and 10 minutes at a cadence 20% below FCC (FCC-20%). Pedal forces and kinematics were evaluated. The resultant force (RF), effective force (EF), index of effectiveness (IE) and IE during propulsive and recovery phase (IEprop and IErec, respectively) were computed. For W(60%), FCC-20% and FCC presented higher EFmean (69+/-9 N and 66+/-14 N, respectively) than FCC+20% (52+/-14 N). FCC presented the highest IEprop (81+/-4%) among the cadences (74+/-4 and 78+/-5% for FCC-20% and FCC+20%, respectively). For W(80%), FCC presented higher EFmean (81+/-5 N) than FCC+20% (72 +/- 10 N). The FCC-20% presented the lower IEprop (71+/-7%) among the cadences. The EFmin was higher for W(80%) than W(60%) for all cadences. The IE was higher at W (80%) (61+/-5%) than W (60%) (54+/-9%) for FCC+20% (all p<0.05). Lower cadences were more effective during the recovery phase for both intensities and FCC was the best technique during the propulsive phase.

Temporomandibular joint dysfunction and trapezius muscle fatigability

INTRODUCTION: It has been suggested that pain increases trapezius muscle activation in patients with temporomandibular joint dysfunction (TMD). Changes in muscle activation might change muscle resistance to fatigue. The purpose of this study was to evaluate the fatigability of the trapezius muscle in patients with TMD. METHOD: Fourteen patients with TMD (clinically diagnosed and referred by a dentist) and eleven healthy subjects performed a fatigue test consisting of shoulder elevation performed at 70 percent of the maximal voluntary isometric contraction, which was maintained for 30 seconds. Electromyographic signals were obtained from the upper portion of the trapezius muscle (sampling frequency: 2000 Hz/channel). Consecutive segments of three seconds in duration each were extracted from the electromyographic signal and analyzed in the frequency domain using a Fast Fourier Transform algorithm. Linear regression analysis was applied to the consecutive median frequencies for each subject. The slope of the regression line was used to describe muscle fatigability. RESULTS: No changes were observed in fatigability between the right and left trapezius of either group or between the left trapezius of the healthy and TMD groups. The linear regression for median frequencies in the right trapezius of the TMD group showed a slope of -0.15 ± 0.33 (mean ± SD), which was smaller than the slope for the healthy group (-0.44 ± 0.46; p= 0.049). These results suggested that the fatigability of the right trapezius was lower in the TMD group than in the healthy group.

INTRODUÇÃO: Tem sido sugerido que a dor aumenta a ativação do músculo trapézio em pacientes com disfunção temporomandibular (TMD). Mudanças na ativação do músculo podem alterar a resistência à fadiga. O objetivo do estudo foi investigar a fatigabilidade do músculo trapézio em pacientes com TMJ. MÉTODOS: Quatorze indivíduos com TMD (diagnosticados clinicamente e encaminhados pelo especialista odontólogo) e onze indivíduos saudáveis realizaram um protocolo de fadiga que consistiu em uma contração isométrica submáxima de elevação do ombro, em um nível de 70 por cento da contração voluntária máxima, mantida por um período de 30 segundos. O sinal eletromiográfico (EMG) foi obtido da porção superior do músculo trapézio, (taxa de amostragem de 2000Hz/canal). Três segundos consecutivos do sinal EMG foram analisados no domínio da freqüência usando a Transformada Rápida de Fourier (FFT). Uma análise de regressão linear foi aplicada para valores consecutivos da freqüência mediana (MF) de cada sujeito, e a inclinação da regressão linear foi utilizada para descrever a fatigabilidade muscular. RESULTADOS: Nenhuma diferença foi observada na fatigabilidade do músculo trapézio direito e esquerdo para ambos os grupos e entre o trapézio esquerdo do grupo saudável e com TMD. A MF do músculo trapézio direito do grupo com disfunção apresentou valores de inclinação da reta de regressão linear de -0,15 ± 0,33 (média ± SD), os quais foram menores que os valores do grupo saudável (-0,44 ± 0,46; média ± SD; p= 0,049). Esses resultados sugerem que a fatigabilidade do trapézio direito é menor no grupo com TMD do que no grupo saudável.