Effect Of Caffeine Intake On Critical Power Model Parameters Determined On A Cycle Ergometer [efeito Da Ingestão De Cafeína Sobre Os Parâmetros Da Potência Crítica]
The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p<0.01). A high association (r2) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration.1214954Davis, J.M., Zhao, Z., Stock, H.S., Mehl, K.A., Buggy, J., Hand, G.A., Central nervous system effects of caffeine and adenosine on fatigue (2003) Am J Physiol, 284 (SUPPL.), pp. R399-R404Graham, T.E., Caffeine and exercise: Metabolism, endur-endurance and performance (2001) Sports Med, 31 (11), pp. 785-807Lindinger, M.I., Graham, T.E., Spriet, L.L., Caffeine attenuates the exercise-induced increases in plasma [K+] in humans (1993) J Appl Physiol, 74 (3), pp. 1149-1155Tarnopolsky, M.A., Cupido, C., Caffeine potentiates low frequency skeletal muscle force in habitual and nonhabitual caffeine users (2000) J Appl Physiol, 89 (5), pp. 1719-1724Graham, T.E., Rush, J.W., van Soeren, M.H., Caffeine and exercise: Metabolism and performance (1994) Can J Appl Physiol, 19 (2), pp. 111-138Greer, F., Friars, D., Graham, T.E., Comparison of caffeine and theophylline ingestion: Exercise metabolism and endurance (2000) J Appl Physiol, 89 (5), pp. 1837-1844Bruce, C.R., Anderson, M.E., Fraser, S.F., Stepto, N.K., Klein, R., Hopkins, W.G., Enhancement of 2000-m rowing performance after caffeine ingestion (2000) Med Sci Sports Exerc, 32 (11), pp. 1958-1963Doherty, M., Smith, P.M., Hughes, M.G., Davison, R.C., Caffeine lowers percentual response and increases power output during high-intensity cycling (2004) J Sports Sci, 22 (7), pp. 637-643Jackman, M., Wendling, P., Friars, D., Graham, T.E., Metabolic, catecholamine and endurance responses to caffeine during intense exercise (1996) J Appl Physiol, 81 (4), pp. 1658-1663Spriet, L.L., Caffeine and performance (1995) Int J Sports Nutr, 5 (SUPPL.), pp. S84-S99Kalmar, J.M., Caffarelli, E., Caffeine: A valuable tool to study central fatigue in humans (2004) Exerc Sport Sci Rev, 32 (4), pp. 143-147Monod, H., Sherrer, J., The work capacity of a synergic muscular group (1965) Ergonomics, 8 (3), pp. 329-338Wakayoshi, K., Ilkuta, K., Yoshida, T., Determination and validity of critical velocity speed as an index of swimming performance in the competitive swimmer (1992) Eur J Appl Physiol Occup Physiol, 64 (2), pp. 153-157Wakayoshi, K., Yoshida, T., Udo, M., Harada, T., Moritani, T., Mutoh, Y., Does critical swimming velocity represent exercise intensity at maximal lactate steady state (1993) Eur J Appl Physiol Occup Physiol, 66 (1), pp. 90-95Moritani, T., Nagata, A., Devries, H., Muro, M., Critical power as a measure of physical work capacity and anaerobic threshold (1981) Ergonomics, 24 (5), pp. 339-350le Chevalier, J.M., Vandewalle, H., Thépaut-Mathieu, C., Stein, J.F., Caplan, L., Local critical power is an index of local endurance (2000) Eur J Appl Physiol, 81 (1-2), pp. 120-127Hill, D.W., Smith, J.C., A method to ensure the accuracy of estimates of anaerobic capacity derived using the critical power concept (1994) J Sports Med Phys Fitness, 34 (1), pp. 23-37Calis, J.F., Denadai, B.S., Influência das cargas selecionadas na determinação da potência crítica determinada no ergômetro de braço em dois modelos lineares (2000) Rev Bras Med Esporte, 6 (1), pp. 1-4Housh, D.J., Housh, T.J., Bauge, S.M., A methodological consideration for the determination of critical power and anaerobic work capacity (1990) Res Quarterly Exerc Sport, 61 (4), pp. 406-409Miura, A., Sato, H., Whipp, B.J., Fukuba, Y., The effect of glycogen depletion on the curvature constant parameter of the power-duration curve for cycle ergometry (2000) Ergonomics, 46 (1), pp. 133-141Smith, J.C., Stephens, D.P., Hall, E.L., Jackson, A.W., Earnest, C.P., Effect of oral creatine ingestion on parameters of work-time relationship and time to exhaustion in high-intensity cycling (1998) Eur J Appl Physiol, 77 (4), pp. 360-365Eckerson, J.M., Stout, J.R., Moore, G.A., Stone, N.J., Nishimura, K., Tamura, K., Effect of two and five days of creatine loading on anaerobic working capacity in women (2004) J Strength Condit Res, 18 (1), pp. 168-173Jenkins, D.G., Quigley, B.M., Endurance training enhances critical power (1992) Med Sci Sports Exerc, 24 (11), pp. 1283-1289Jenkins, D.G., Quigley, B.M., The influence of high-intensity exercise training on the Wlin-Tlim relationship (1993) Med Sci Sports Exerc, 25 (2), pp. 275-282Anselme, F., Collomp, K., Mercier, B., Ahmaidi, S., Prefaut, C., Caffeine increases maximal anaerobic power and blood lactate concentration (1992) Eur J Appl Physiol, 65 (2), pp. 188-191Paton, C.D., Hopkins, W.G., Volebregt, L., Little effect of caffeine ingestion on repeated sprints in team-sport athletes (2001) Med Sci Sports Exerc, 33 (5), pp. 822-825Jackman, M., Wendling, A., Friars, D., Graham, T.E., Metabolic, catecholamine, and endurance responses to caffeine during intense exercise (1996) J Appl Physiol, 81 (4), pp. 1658-1663Doherty, M., The effects of caffeine on the maximal accumulated oxygen deficit and short-term running performance (1998) Int J Sports Nutr, 8 (2), pp. 95-104Bell, D.G., Jacobs, I., Ellerington, K., Effect of caffeine and ephedrine ingestion on anaerobic exercise performance (2001) Med Sci Sports Exerc, 33 (11), pp. 1399-1403Alves, M.N., Ferrari-Auarek, W.M., Pinto, K.M.C., Sá, K.R., Viveiros, J.P., Pereira, H.A.A., Effects of caffeine on tryptophan on rectal temperature, metabolism, total exercise time, rate of perceived exertion and heart rate (1995) Braz J Med Biol Res, 28 (6), pp. 705-709Butts, N.K., Crowell, D., Effect of caffeine ingestion on cardiorespiratory endurance in men and women (1985) Res Q Exerc Sport, 56 (4), pp. 301-30
