INFLUENCIA DEL PROCEDIMIENTO EMPLEADO PARA DETERMINAR LA RECTA DE ECONOMÍA DE PEDALEO EN EL CÁLCULO DEL DÉFICIT MÁXIMO DE OXÍGENO ACUMULADO

<br /><div><p align="center"><strong>RESUMEN</strong></p></div> <p align="justify">Para determinar la influencia que tienen en los valores de DMO, el número, intensidad y duración de las cargas submáximas utilizadas para calcular la recta de economía, 6 varones acudieron al laboratorio en 8 ocasiones. Tras la familiarización, se determinó el VO<sub>2</sub> pico, y el el VO<sub>2</sub> a 80, 100, 110, 120, 130, 140, 150, 160, 180, 200 y nuevamente 100 w. Se calcularon 4 rectas diferentes por regresión lineal: R1, R2, R3, R4. Las rectas R1, R2 y R4 se obtuvieron a partir de la relación VO<sub>2</sub>/intensidad, entre 80 y 130 w (R1, n=5), entre 140 y 200 w (R2, n=5) y entre 80 y 200 w (R4, n=10), tomando como valor de VO<sub>2</sub> correspondiente a cada carga el valor medio alcanzado en los minutos 5 y 6. R3 se calculó a partir de la relación VO<sub>2</sub>/intensidad, entre 80 y 200 w en test incremental hasta el agotamiento (n=4), tomando como valor de VO<sub>2</sub> correspondiente a cada carga el valor medio alcanzado en el 3er min. Finalmente, se calculó el déficit máximo de O<sub>2</sub> (DMO) en un test de Wingate de 45 s.</p> <p align="justify">R4 y R3 presentaron parámetros similares, que no se correlacionaron entre sí. Las pendientes fueron un 15 % inferiores en R1 que en R2 (9.591 ± 1.236 y 11.261 ± 0.878 ml.min-1, respectivamente, p<0.05), mientras la ordenada en el origen fue mayor en R1 que en R2 (709.216 ± 154.808 y 510.583 ± 114.204 ml.min-1, respectivamente, p<0.05). Entre R1 y R2 tampoco se obtuvieron correlaciones significativas ni entre pendientes, ni entre puntos de intercepción. Los valores de DMO fueron un 18 % superiores, cuando la recta de economía se obtuvo mediante cargas altas (R2) que cuando se obtuvo mediante cargas bajas (R1; p=0.06). El índice de correlación del DMO calculado con R3 y R4 no fue significativo (r=0.76, p=0.08). Sin embargo, se obtuvo una correlación muy alta entre los valores de DMO con R2 y R4 (r=0.99, p<0.001). Este estudio demuestra que los valores de DMOA presentan un variabilidad importante en función del procedimiento seguido para determinar la recta de economía de pedaleo.<br />PALABRAS CLAVE: Ejercicio, economía de pedaleo, eficiencia, fiabilidad y deficit de oxígeno.</p> <p align="justify"> </p> <p class="titulo1" align="center"><strong>ABSTRACT</strong></p> <p align="justify">To assess the effect on the maximal oxygen deficit (MOD) of the intensity, the duration and the number of bouts utilized to calculate the submaximal VO<sub>2</sub>/intensity relationship, six males were tested on eight separate days. After familiarization, an incremental exercise test was used to assess the VO<sub>2</sub>peak an another three tests were performed to obtain the submaximal VO<sub>2</sub>/intensity relationship at the following intensities: 80, 100, 110, 120, 130, 140, 150, 160, 180, 200 and another time 100 w. Four different linear regressions were calculated: R1, R2, R3 and R4. R1, R2 and R4 were calculated from the VO<sub>2</sub>/intensity relationship between 80 and 130 w (R1, n=5), 140 y 200 w (R2, n=5) and 80 y 200 w (R4, n=10). The VO<sub>2</sub> for each submaximal bout was taken as the mean for the last two min (i.e., the 5th and 6th min). Subsequently, R3 was obtained from the VO<sub>2</sub>/intensity relationship between 80 and 200 w (R3, n=4) during an incremental exercise test to exhaustion with 40 w steps every 3 min, using the mean VO<sub>2</sub> reached at the third min. Lastly, the maximal oxygen deficit (MOD) was calculated for a 45-s Wingate test.</p> <p align="justify">There were no significant differences between R4 and R3. However, the pendents and the intercepts were not correlated. The pendents were 15% lower for R1 than for R2 (9.591 ± 1.236 y 11.261 ± 0.878 ml.min-1, respectively, p<0.05), while the intercepts were higher for R1 than for R2 (709.216 ± 154.808 y 510.583 ± 114.204 ml.min-1, respectively, p<0.05). Between R1 and R2, neither the pendents nor the intercepts were correlated. The MOD calculated from R2 was 18% higher than that obtained from R1 (p=0.06). The Pearson correlation coefficient between the MOD values derived from R3 and R4 was not significant (r=0.76, p=0.08). Conversely, a close correlation was found between MOD obtained from R2 and R4 (r=0.99, p<0.001). This study shows that the MOD shows a high variability dependent on the procedure utilized to calculate the VO<sub>2</sub>/intensity relationship.<br />KEY WORDS: Exercice, cycling economy, efficiency, reliability, oxygen deficit.</p&gt

Effect of pedaling cadence on muscle oxygenation during high-intensity cycling until exhaustion: a comparison between untrained subjects and triathletes

Purpose: The aim of this study was to compare the muscle oxygenation between trained and untrained subjects during heavy exercise until exhaustion at two extreme pedaling cadences using a NIRS system. Methods: Nine untrained male subjects and nine male competitive triathletes cycled until exhaustion at an intensity corresponding to 90 % of the power output achieved at peak oxygen uptake at 40 and 100 rpm. Gas exchanges were measured breath-by-breath during each exercise. Muscle (de) oxygenation was monitored continuously by near-infrared spectroscopy on the Vastus Lateralis. Results: Muscle deoxygenation (Delta deoxy[Hb + Mb], i.e., O-2 extraction) and Delta total[Hb + Mb] were significantly higher at 40 rpm compared to 100 rpm during the exercise in untrained subjects but not in triathletes (p < 0.05). The time performed until exhaustion was significantly higher at 40 than at 100 rpm in untrained subjects (373 +/- 55 vs. 234 +/- 37 s, respectively) but not in triathletes (339 +/- 69 vs. 325 +/- 66 s). Conclusions: These results indicate that high aerobic fitness (1) allows for better regulation between (V) over dotO(2M) and (Q) over dot O-2M following the change in pedaling cadence, and (2) is the most important factor in the relationship between pedaling cadence and performance

The influence of crank length and cadence on mechanical efficiency in hand cycling

The purpose of this study was to determine the effect of crank length and cadence on mechanical efficiency in hand cycling. Eight wheelchair dependent, high performance athletes completed four 4-min submaximal exercise bouts at a constant power output of 90 W over the different experimental conditions (crank length, pedal rate) using a sports hand bike (Draft, Godmanchester, UK). Two different crank lengths (180 and 220 mm) were tested at two different cadences (70 and 85 rev min−1) using the synchronous mode of cranking. Physiological measures of oxygen uptake VO2, minute ventilation, blood lactate (B[La]), heart rate (HR), rate of perceived exertion (RPE) were recorded, gross (GE) and net (NE) efficiency were calculated. A two-way ANOVA with repeated measures was applied to determine the effects of crank length, cadence and their interaction on these physiological measures. Both GE and NE were significantly higher and VO2 significantly lower for the 180 mm crank (P 0.05). Likewise, no interactions between crank length and pedal rate were found. There was however, a trend observed with HR and B[La] often lower with the 180 mm crank, indicating lower physiological stress. The RPE data supported this finding, with a tendency for lower ratings with the 180 mm crank (9 ± 2 vs. 10 ± 3). The short crank length when used at 85 rev min−1 was found to be the most efficient (GE 21.4 ± 3.1%). In conclusion, crank length has a significant effect on ME in hand cycling. A shorter crank length of 180 mm was found to be more efficient than the 220 mm, regardless of pedal rate during hand cycling