Modeling the expenditure and reconstitution of distance above critical speed during two swimming interval training sessions.

In swimming, the speed-time relationship provides the critical speed (CS) and the maximum distance that can be performed above CS (D'). During intermittent severe intensity exercise, a complete D' depletion coincides with task failure, while a sub-CS intensity is required for D' reconstitution. Therefore, determining the balance D' remaining at any time during intermittent exercise (D'BAL) could improve training prescription. This study aimed to 1) test the D'BAL model for swimming; 2) determine an equation to estimate the time constant of the reconstitution of D' (τD'); and 3) verify if τD' is constant during two interval training sessions with the same work intensity and duration and recovery intensity, but different recovery duration. Thirteen swimmers determined CS and D' and performed two high-intensity interval sessions at a constant speed, with repetitions fixed at 50 m. The duration of passive recovery was based on the work/relief ratio of 2:1 (T2:1) and 4:1 (T4:1). There was a high variability between sessions for τD' (coefficient of variation of 306%). When τD' determined for T2:1 was applied in T4:1 and vice versa, the D'BAL model was inconsistent to predict the time to exhaustion (coefficient of variation of 29 and 28%). No linear or nonlinear relationships were found between τD' and CS, possibly due to the high within-subject variability of τD'. These findings suggest that τD' is not constant during two high-intensity interval sessions with the same recovery intensity. Therefore, the current D'BAL model was inconsistent to track D' responses for swimming sessions tested herein.

Consumo de oxigênio no domínio de intensidade severo durante teste incremental e retangular / Oxygen consumption in the severe exercise intensity domain during incremental and square-wave test modes

Testes incrementais são comumente utilizados para predizer respostas metabólicas durante exercício retangular, porém, em alguns casos, os resultados preditos e observados podem não ser semelhantes. Objetivo principal: Verificar a hipótese de que o VO2 determinado em algumas intensidades do domínio severo, durante teste incremental, é menor do que os valores observados em testes retangulares. Procedimentos metodológicos: Oito homens fisicamente ativos (21,5 ± 4 anos, 73,7 ± 5,3 kg e 180,8 ± 4,1 cm) realizaram: 1) teste incremental em cicloergômetro para determinação do VO2 das intensidades (VO2INC); 2) testes retangulares em três intensidades severas (Leve (L), Média (M) e Pesada (P)) para comparar o VO2 (VO2RET) observado com o VO2INC correspondente, adicionalmente, determinar a potência crítica (PCrit); 3) teste retangular na intensidade da PCrit para comparar a resposta temporal do VO2 com P, M e L em quatro momentos. Resultados: O VO2INC, na intensidade L, subestimou o VO2RET (3,2 ± 0,5 vs. 3,8 ± 0,6 l.min-1), não houve diferença nas outras intensidades (M: 3,5 ± 0,5 vs. 3,6 ± 0,5 l.min-1; P: 3,7 ± 0,5 vs. 3,4 ± 0,6 l.min-1; PCrit: 2,7 ± 0,5 vs. 3,0 ± 0,6 l.min-1). O VO2 na PCrit foi menor em todos os momentos, apresentou estabilização e não atingiu o VO2max. Inicialmente, na intensidade L, o VO2 foi menor do que seus pares. Contudo, no momento fi nal, atingiu o VO2max e se igualou às outras intensidades severas. Conclusão: O teste incremental subestima o VO2 observado em testes retangulares para intensidades mais leves do domínio severo.

Incremental tests are commonly used to predict metabolic responses during square-wave mode exercises. However, in some cases the predicted and observed results may be not similar. Main objective: To verify the hypothesis that, at certain intensities in the severe domain, VO2 determined during the incremental test is lower than that observed at these workloads using the square-wave test. Methodological proceedings: Eight physically active males (21.5 ± 4 years, 73.7 ± 5.3 kg and 180.8 ± 4.1 cm) performed: 1) an incremental test on cycle ergometer to determine the VO2 of the intensities (VO2INC); 2) a square-wave test at three severe intensities (Light (L), Medium (M) and Heavy (H)) to determine the critical power (CP) and to compare the VO2 (VO2RET) observed with the VO2INC; 3) a square-wave test at CP intensity to compare the time response of VO2 with P, M and L, at four different sample times. Results: The VO2INC at L intensity underestimated the VO2RET (3.2 ± 0.5 vs. 3.8 ± 0.6 l.min-1). No differences were observed at the other intensities (M: 3.5 ± 0.5 vs. 3.6 ± 0.5l.min-1; H: 3.7 ± 0.5 vs. 3.4 ± 0.6 l.min-1; CP: 2.7 ± 0.5 vs. 3.0 ± 0.6 l.min-1). The VO2 at CP was lower at all times, exhibited a steady state and did not achieve VO2max. Initially, at L intensity, the VO2 was smaller than its pairs. However, at the last sample time, it achieved VO2max and became equal to the other severe intensities. Conclusion: The incremental test underestimates the VO2 observed at lighter intensities within the severe domain.