Predicting Lactate Threshold With Rate of Perceived Exertion in Young Competitive Male Swimmers.

The purpose of this study was to verify the effectiveness of the rate of perceived exertion threshold (RPET) for predicting young competitive swimmers' lactate threshold (LT) during incremental testing. We enrolled 13 male athletes (M age = 16, SD = 0.6 years) in an incremental test protocol consisting of eight repetitions of a 100-meter crawl with 2-minute intervals between each repetition. We collected data for blood lactate concentration ([La]) and Borg scale rate of perceived exertion (RPE) at the end of each repetition. The results obtained were: M RPET = 4.98, SD = 1.12 arbitrary units (A.U.) and M lactate threshold = 4.24, SD = 1.12 mmol.L-1, with [La] and RPE identified by the maximal deviation (Dmax) method without a significant difference (p > 0.05) and large correlations between DmaxLa and DmaxRPE at variables for time (r = 0.64), velocity (r = 0.67) and percentage of personal best time (PB) (r = 0.60). These results suggest that RPET is a good predictor of LT in young competitive swimmers.

Determinação da relação potência-duração em exercício com membros superiores / Determination of the power-duration relationship in upper-limb exercises

OBJETIVOS: Determinar a relação potência-duração em exercícios de membros superiores (MMSS) e verificar a relação dos parâmetros derivados dessa função com indicadores fisiológicos de aptidão aeróbia. Métodos: Dez homens saudáveis (26,2±2,3 anos, 75,0±11,8 kg, 178,2±11,5 cm e 15,0±5,7 por cento de gordura) realizaram um teste de rampa em cicloergômetro de braço com incrementos de 20 W/min. Posteriormente, cinco testes de carga constante até a exaustão a 70, 80, 90, 95 e 100 por cento da diferença entre LV1 e o VO2pico foram realizados. A potência crítica (PC) foi obtida por meio da linearização da função potência-duração. RESULTADOS: A relação potência-duração foi descrita pela função ajustada (r=0,98±0,02). O VO2 na PC (2,66±0,62 l/min) foi maior do que no LV1 (1,62±0,38 l/min) e LV2 (2,36±0,59 l/min, respectivamente), mas menor do que o VO2pico (3,06±0,62 l/min). A carga da PC (103,0±26,0 W) foi diferente da encontrada em LV1 (69,5±21 W) e VO2pico (151,0±26,3 W), mas não da em LV2 (103,5±30,8 W). A associação entre a PC e esses indicadores de aptidão aeróbia foram todas significantes quando expressas em VO2 (0,73 a 0,78; p<0,05) e em W (0,83 a 0,91; p<0,05). A determinação da PC em exercícios dinâmicos de MMSS é simples e de baixo custo, podendo ser utilizada pelo fisioterapeuta na prescrição e avaliação do treinamento de MMSS. CONCLUSÃO: A relação potência-duração em exercícios com os MMSS pode ser descrita por uma função hiperbólica e está associada a indicadores fisiológicos da aptidão aeróbia.

OBJECTIVES: To determine the power-duration relationship in upper limb exercises and to investigate the relationships between parameters derived from this function with physiological indicators of aerobic fitness. METHODS: Ten healthy men (26.2±2.3 years, 75.0±11.8 kg, 178.2±11.5 cm and 15.0±5.7 percent body fat) performed a ramped test on an arm cycle ergometer with increments of 20 W/min. Subsequently, five tests with constant load were performed until exhaustion, with 70, 80, 90, 95 and 100 percent difference between VT1 and VO2peak. The critical power (CP) was obtained by means of linearization of the power-duration function. RESULTS: The power-duration relationship was described using an adjusted function (r=0.98±0.02). The VO2 at CP (2.66±0.62 l/min) was higher than VT1 (1.62±0.38 l/min) and VT2 (2.36±0.59 l/min), but lower than VO2peak (3.06±0.62 l/min). The CP workload (103.0±26 W) was significantly different from VT1 (69.5±21 W) and VO2peak workloads (151.0±26.3), but was no different of VT2 (103.5±30.8 W). The association between critical power and aerobic condition indexes were always significant when expressed as VO2 (0.73 to 0.78, p<0.05) and in W (0.83 to 0.91, p<0.05). Determination of CP in upper-limb dynamic exercises is simple and inexpensive, and can be used by physical therapists for prescribing and evaluating upper-limb training programs. CONCLUSIONS: The power-duration relationship in upper-limb exercises can be described by a hyperbolic function and it is associated with physiological indicators of aerobic fitness.