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Abstract Background/Aim Determine critical speed (CS) and running distance above CS (D'), as estimated from the 3-min all-out running test (3MT) is reliable and predictive of CS and D' determined from time trials. Methods Seven males (26 ± 5 years, VO2max: 56.6 ± 4.1 ml·kg-1·min-1) completed an incremental treadmill test, three separate time trials (Tlim) of 800, 1600, and 2400m to determine CS and D', and two 3MTs to estimate CS and D'. Results Estimates of trial 1 (CS =3.90±0.41 m·s-1, D'=176±42 m) and trial 2 (CS=3.89 ± 0.48 m·s-1, D' = 183±35 m) of the 3MT did not differ. Estimates of CS (ICC=0.95, CV=2.97%) and D' (ICC=0.93, CV=5.12%) from the 3MT were reliable. The 3MT trials provided valid estimates of CS as determined using regression of the three time trials (ICCs ranged 0.88-0.93, TE ranged 0.13-0.15 m·s-1, CV ranged 3.32-4.76%). The 3 MT underestimated D' by∼16%, a difference exceeding the test-retest variability. Conclusions Estimates of CS were valid and reliable; however, assessment of D' from the 3MT may not estimate anaerobic capacity accurately.

Resumo Antecedentes/Objetivo Determinar se a velocidade crítica (CS) e a distância acima da CS (D'), estimadaso pelo teste de três minutos máximo (3MT) é confiável e preditiva de CS e D' determinada a partir dos modelos lineares. Métodos Sete homens (26 ± 5 anos, VO2max:56,6 ± 4,1 ml·kg-1·min-1) completaram um teste incremental em esteira, três tomadas de tempo separadamente para 800, 1.600 e 2.400 m, para determinar CS e D' e 2 3MTs para estimar CS e D'. Resultados O primeiro 3 MT (CS = 3,90 ± 0,41 m·s-1, D' = 176 ± 42m) e o segundo 3 MT (CS = 3,89 ± 0,48 m·s-1, D' = 183 ± 35m) não foram diferentes. Estimativas do CS (ICC = 0,95, CV = 2,97%) e D' (ICC = 0,93, CV = 5,12%) a partir de 3 MT eram confiáveis. Os 3 MTs forneceram estimativas válidas de CS (ICC variou de 0,88-0,93, variaram de 0,13 a 0,15 ms TE, CV variou de 3,32 a 4,76%); 3 MT subestimou D' em ∼16%, uma diferença maior de variabilidade teste-reteste. Conclusões Estimativas CS são válidas e confiáveis. No entanto, a avaliação de D' a partir do 3MT não pode estimar com precisão a capacidade anaeróbica.

Antecedentes/Objetivos Determinar si la velocidad crítica (VC) y la distancia por encima de la VC (D'), según la estimación de la prueba de 3 minutos máximos (3MT) es fiable y predictiva de la VC y la D' determinada a partir de los mejores tiempos de carrera personales. Métodos Siete varones (26 ± 5 años, VO2máx: 56,6 ± 4,1 ml·kg-1·min-1) completaron una prueba progresiva en la cinta de correr, con tres períodos de tiempo separados de 800, 1.600 y 2.400 m para determinar la VC y la D' y dos 3MT para estimar la VC y la D'. Resultados Las estimaciones del ensayo 1 (VC = 3,90 ± 0,41 m·s-1, D' = 176 ± 42 m) y del ensayo 2 (VC = 3,89 ± 0,48 m·s-1, D' = 183 ± 35 m) de la prueba 3MT no fueron diferentes. Las estimaciones de la VC (ICC = 0,95; CV = 2,97%) y D' (ICC = 0,93; CV = 5,12%) a partir de la prueba 3MT fueron fiables. Las pruebas 3MT proporcionaron estimaciones válidas de la VC, como se determinó mediante regresión de las tres pruebas de tiempo (ICC se clasificaron desde 0,88 hasta 0,93 y la TE osciló entre 0,13 y 0,15 m.s-1, la CV varió del 3,32 al 4,76%). La D' 3MT subestimó el ∼16%, una diferencia superior a la variabilidad test-retest. Conclusiones Las estimaciones de VC fueron válidas y fiables; Sin embargo, la evaluación de D' desde la prueba de 3MT no puede estimar con precisión la capacidad anaeróbica.

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PURPOSE: Although ischaemic preconditioning (IPC), induced by cycles of transient limb ischaemia and reperfusion, seems to improve exercise performance, the optimal duration of ischaemia-reperfusion cycles is not established. The present study investigated the effect of ischaemia-reperfusion duration within each IPC cycle on performance in a 2000-m rowing ergometer test. METHODS: After incremental and familiarization tests, 16 trained rowers (mean ± SD: age, 24 ± 11 years; weight, 74.1 ± 5.9 kg; [Formula: see text] peak, 67.2 ± 7.4 mL·kg-1·min-1) were randomly submitted to a 2000-m rowing test preceded by intermittent bilateral cuff inflation of the lower limbs with three cycles of ischaemia-reperfusion, lasting 5 min (IPC-5) or 10 min (IPC-10) at 220 or 20 mmHg (control). Power output, [Formula: see text], heart rate, blood lactate concentration, pH, ratings of perceived exertion (RPE), and near-infrared spectroscopy-derived measurements of the vastus lateralis muscle were continuously recorded. RESULTS: No differences among treatments were found in the 2000-m test (control: 424 ± 17; IPC-5: 425 ± 16; IPC-10: 424 ± 17 s; P = 0.772). IPC-10 reduced the tissue saturation index and oxy-haemoglobin concentration during exercise compared with control. The power output during the last 100-m segment was significantly lower with IPC-10. The IPC treatments increased the heart rate over the first 500 m and decreased the pH after exercise. No alterations were observed in [Formula: see text], blood lactate, or RPE among the trials. CONCLUSION: In conclusion, IPC does not improve the 2000-m rowing ergometer performance of trained athletes regardless of the length of ischaemia-reperfusion cycles.

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Resumo O objetivo deste estudo foi determinar o modo e o grau com que variáveis aeróbias e anaeróbias influenciam o desempenho e a fadiga em "sprints" repetidos (RS) na corrida. Para este fim, participaram do estudo 24 homens, sendo oito corredores velocistas, oito corredores fundistas e oito sujeitos ativos. Em uma pista sintética de atletismo estes sujeitos foram submetidos aos seguintes testes: 1) teste incremental para determinação do VO2max e da velocidade aeróbia máxima (VAM); 2) teste de velocidade constante realizado a 110%VAM para determinar a cinética do VO2 durante exercício e o máximo déficit acumulado de oxigênio (MAOD); 3) teste de "sprints" repetidos (10 "sprints" de 35 m, intercalados com 20 s de recuperação) para determinar o tempo total dos "sprints" (TT), tempo do melhor sprint (TM) e a queda do desempenho em percentual (Sdec). Para analisar a diferença entre os grupos e as relações entre as variáveis foram utilizadas a análise de variância ANOVA "one-way", complementada pelo teste de Tukey, e a correlação de Pearson, respectivamente. O TT em RS foi diferente significativamente entre todos os grupos (velocistas, 49,5 ± 0,8 s; fundistas, 52,6 ± 3,1 s; ativos, 55,5 ± 2,6 s) e Sdec foi significativamente inferior em fundistas comparado aos outros grupos (velocistas, 8,9 ± 2,1%; fundistas, 4,0 ± 2,0%; ativos, 8,4 ± 4,4%). O TT foi correlacionado significativamente com o TM (r = 0,85, p < 0,01) e com o MAOD (r = - 0,54, p < 0,01). Além disso, Sdec foi correlacionado significativamente com variáveis aeróbias (VO2max, r = - 0,58, < 0,01; VAM, r = - 0,59, p < 0,01; constante de tempo "tau", r = 0,45, p = 0,03). Portanto, conclui-se que apesar de índices aeróbios influenciarem na redução da fadiga em RS, o desempenho em RS é principalmente influenciado por características anaeróbias.(AU)

Abstract This study aimed to determine the manner and degree to which aerobic and anaerobic variables influence repeated running sprint performance and ability. Twenty four males (sprinters = 8, endurance runners = 8 and physical active subjects = 8) performed in a synthetic track the following tests: 1) incremental test to determine the VO2max and the maximum aerobic velocity (MAV); 2) constant velocity test performed at 110% of MAV to determine the VO2 kinetics and the maximum accumulated oxygen deficit (MAOD); 3) repeated sprint test (10 sprints of 35-m interspersed by 20s) to determine sprint total time (TT), best sprint time (BT) and score decrement (Sdec). Between-groups comparisons and the correlations between variables were analyzed by one-way ANOVA with a Tukey post-hoc tests and Pearson correlation, respectively. TT was significantly different among all groups (sprinters = 49.5 ± 0.8 s; endurance = 52.6 ± 3.1 s; active = 55.5 ± 2.6 s) and Sdec was significantly lower in endurance runners as compared with sprinters and physical active subjects (sprinters = 8.9 ± 2.1%; endurance = 4.0 ± 2.0%; active = 8.4 ± 4.4%). TT correlated significantly with BT (r = 0.85, p < 0.01) and MAOD (r = - 0.54, p < 0.01). Moreover, Sdec was significantly correlated with aerobic parameters (VO2max, r = - 0.58, p < 0.01; MAV, r = - 0.59, p < 0.01; time constant tau, r = 0.45, p = 0.03). In conclusion, although the aerobic parameters have an important contribution to RS ability, RS performance is mainly influenced by anaerobic parameters.(AU)

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It has been demonstrated that ischemic preconditioning (IPC) improves endurance performance. However, the potential benefits during anaerobic events and the mechanism(s) underlying these benefits remain unclear. Fifteen recreational cyclists were assessed to evaluate the effects of IPC of the upper thighs on anaerobic performance, skeletal muscle activation, and metabolic responses during a 60-s sprint performance. After an incremental test and a familiarization visit, subjects were randomly submitted in visits 3 and 4 to a performance protocol preceded by intermittent bilateral cuff inflation (4 × (5 min of blood flow restriction + 5 min reperfusion)) at either 220 mm Hg (IPC) or 20 mm Hg (control). To increase data reliability, each intervention was replicated, which was also in a random manner. In addition to the mean power output, the pulmonary oxygen uptake, blood lactate kinetics, and quadriceps electromyograms (EMGs) were analyzed during performance and throughout 45 min of passive recovery. After IPC, performance was improved by 2.1% compared with control (95% confidence intervals of 0.8% to 3.3%, P = 0.001), followed by increases in (i) the accumulated oxygen deficit, (ii) the amplitude of blood lactate kinetics, (iii) the total amount of oxygen consumed during recovery, and (iv) the overall EMG amplitude (P < 0.05). In addition, the ratio between EMG and power output was higher during the final third of performance after IPC (P < 0.05). These results suggest an increased skeletal muscle activation and a higher anaerobic contribution as the ultimate responses of IPC on short-term exercise performance.

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Abstract The severe-intensity domain has important applications for the prescription of running training and the elaboration of experimental designs. The objectives of this study were: 1) to investigate the validity of a previously proposed model to estimate the shortest exercise duration (TLOW) and the highest velocity (VHIGH) at which VO2 max is reached during running, and 2) to evaluate the effects of aerobic training status on these variables. Eight runners and eight physically active subjects performed several treadmill running exercise tests to exhaustion in order to mathematically estimate and to experimentally determine TLOW and VHIGH. The relationship between the time to achieve VO2 max and time to exhaustion (Tlim) was used to estimate TLOW. VHIGH was estimated using the critical velocity model. VHIGH was assumed to be the highest velocity at which VO2 was equal to or higher than the average VO2 max minus one standard deviation. TLOW was defined as Tlim associated with VHIGH. Runners presented better aerobic fitness and higher VHIGH (22.2 ± 1.9 km.h-1) than active subjects (20.0 ± 2.1 km.h-1). However, TLOW did not differ between groups (runners: 101 ± 39 s; active subjects: 100 ± 35 s). TLOW and VHIGH were not well estimated by the model proposed, with high coefficients of variation (> 6%) and a low correlation coefficient (r<0.70), a fact reducing the validity of the model. It was concluded that aerobic training status positively affected only VHIGH. Furthermore, the model proposed presented low validity to estimate the upper boundary of the severe-intensity domain (i.e., VHIGH), irrespective of the subjects' training status.

Resumo O domínio severo tem importantes aplicações para a prescrição do treinamento de corrida e elaboração de delineamentos experimentais. O estudo teve como objetivos: 1) investigar a validade de um modelo proposto previamente para estimativa do menor tempo de exercício (TINF) e maior velocidade (VSUP) em que o VO2max é alcançado na corrida; e 2) comparar os efeitos do estado de treinamento nestes parâmetros. Oito corredores e oito indivíduos fisicamente ativos realizaram uma série de testes até a exaustão em esteira rolante para estimar matematicamente e determinar experimentalmente o TINF e VSUP. A relação entre tempo para atingir o VO2 max e tempo de exaustão (Tlim) foi usado para estimar o TINF. A VSUP foi estimada pelo modelo de Velocidade Crítica. VSUP foi assumida como a maior velocidade em que o VO2 ± 2,1 km.h-1. Entretanto, TINF não foi diferente entre grupos (Corredores 101 ± 39; Ativos: 100 ± 35 s). VSUP e TINF não foram bem estimados pelo modelo proposto e apresentaram altos coeficientes de variação (> 6%) e baixa correlação (r < 0,70), o que diminuiu a sua validade. Pode-se concluir que o estado de treinamento aeróbio afetou positivamente apenas a VSUP. Além disso, o modelo proposto apresentou baixa validade para predição do limite superior do domínio severo (VSUP) independentemente do estado de treinamento dos indivíduos.

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The focus of the present study was to investigate the effects of a fast-start pacing strategy on running performance and pulmonary oxygen uptake (VO2) kinetics at the upper boundary of the severe-intensity domain. Eleven active male participants (28±10 years, 70±5 kg, 176±6 cm, 57±4 mL/kg/min) visited the laboratory for a series of tests that were performed until exhaustion: 1) an incremental test; 2) three laboratory test sessions performed at 95, 100 and 110% of the maximal aerobic speed; 3) two to four constant speed tests for the determination of the highest constant speed (HS) that still allowed achieving maximal oxygen uptake; and 4) an exercise based on the HS using a higher initial speed followed by a subsequent decrease. To predict equalized performance values for the constant pace, the relationship between time and distance/speed through log-log modelling was used. When a fast-start was utilized, subjects were able to cover a greater distance in a performance of similar duration in comparison with a constant-pace performance (constant pace: 670 m±22%; fast-start: 683 m±22%; P = 0.029); subjects also demonstrated a higher exercise tolerance at a similar average speed when compared with constant-pace performance (constant pace: 114 s±30%; fast-start: 125 s±26%; P = 0.037). Moreover, the mean VO2 response time was reduced after a fast start (constant pace: 22.2 s±28%; fast-start: 19.3 s±29%; P = 0.025). In conclusion, middle-distance running performances with a duration of 2-3 min are improved and VO2 response time is faster when a fast-start is adopted.

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