Reliability of a laboratory-based long sprint cycling test: applications of the smallest worthwhile changes in performance for repeated measures designs

The aims of the present study were to assess the reliability of long sprint cycling performance in a group of recreationally trained cyclists and to provide thresholds for changes in performance for this particular group of subjects in repeated measures designs through a scale of magnitudes. Repeatability of mean power output during a 1-min cycling time trial was assessed in a group of 15 recreationally trained cyclists (26 ± 5, years, 176 ± 5 cm, 78 ± 8 kg). They were tested on separate days, approximately one week apart. The test and retest values for the whole group of cyclists were 7.0 ± 0.5 W/kg and 6.9 ± 0.6 W/kg (systematic change and 90% confidence limits of -1.0% ± 1.1%). Our results indicated good test-retest reproducibility (typical error of 1.8%, 90% confidence limits of 1.4% to 2.6%; intraclass correlation coefficient of 0.96, confidence limits of 0.91 to 0.99), but suggested a reduction of mean power for the “slower” subjects on retest (-2.0%, 90% confidence limits of ±1.8%). If not monitored, this systematic decrease could interfere in results of studies utilizing groups with similar performance levels, particularly investigating strategies to improve performance in sprint cycling exercises around 1 min. The thresholds for moderate, large, very large and extremely large effects for mean power output on long sprint cycling performance are about 0.4%, 1.3%, 2.3%, 3.6%, and 5.8%, respectively

Influence of occlusal thickness of custom-made mouthgourds on ventilatory parameters, rate of perceived exertion, and peak velocity attained during an incremental test

Custom-made mouthguards are used to prevent orofacial injuries arising from falls and knocks. It has been observed that thicker custom-made mouthguards transmit less force to the mouth owing to their higher energy absorption capacity. However, it is believed that thicker custom-made mouthguards can alter ventilation during exercise because of the higher resistance or restriction of oral airflow. The purpose of this study was to investigate if a thicker custom-made mouthguard (occlusal thickness of 5-mm; 5MG) alters ventilatory parameters, rate of perceived exertion (RPE), and peak velocity during an incremental test relative to a thinner custom-made mouthguard (occlusal thickness of 3-mm; 3MG) and no mouthguard (NoMG). Eleven male amateur contact team sports players completed three running incremental tests on different days. Each test performed with 3MG, 5MG, and without a mouthguard. There were no significant differences in peak velocity during the incremental tests among conditions (14.9 ± 0.6, 14.9 ± 0.7, and 14.7 ± 0.9 km·h-1 for NoMG, 3MG, and 5MG, respectively). Furthermore, no differences were found in the peaks of pulmonary oxygen uptake, minute ventilation, and respiratory frequency, as well as second ventilatory threshold. RPE was higher when wearing 5MG than when running without a mouthguard only at the 12.5 km·h-1 stage (P = .03). These data indicate that wearing custom-made mouthguards with occlusal thicknesses between 3- and 5-mm does not alter ventilatory parameters at the end of an incremental test. Thus, custom-made mouthguards with an occlusal thickness of 5-mm should be preferred owing to their greater protection capacity

Influence of aerobic and anaerobic variables on repeated sprint tests

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, p < 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.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

Effects of remote ischemic preconditioning in subsequent 50 meters performance in swimming

The present study aimed to determine the effects of Ischemic preconditioning (IPC) on 50 meters swim performance, in the technical variables and in blood lactate. Ten federated swimmers (20 ± 3 years, 1.82 ± 0.05 m, 77 ± 5 kg and 24.79 ± 1.04 seconds in the 50 meters freestyle) participated in a repeated measures design. The protocol consisted of three visits, anthropometric assessment were performed in the first visit, the second and third (random order) to three subsequent 50 meters performances in an Olympic pool. The first was performed at one hour (D1), the second at two hours (D2) and third at eight hours (D8) after application of IPC or control condition (CTRL). In addition to performance measurement, was measured the blood lactate accumulation (&#916; [Lac]), furthermore, the technical parameters relating to the stroke length (SL), stroke frequency (SR) and stroke index (SI) were measured over three passages during the race. IPC had a 0.85% mean effect in performance improvement. Although the effect was not significant in D1 (0.37 %, p = 0.25), there was a clear effect of treatment in D2 and D8 (1.02 % and 1.18 %; p < 0.01, respectively). Moreover, the improvement in performance was accompanied by an increasing in &#916;[Lac] in D2 (IPC: 9.04 vs CTRL: 7.77 mmol/L; p < 0.01) and in D8 (IPC: 9.55 vs CTRL: 8.52 mmol/L; p = 0.05), as well as the analysis of technical index during each passage identified a greater SR in D2 and D8. Based on our results, we suggest that a minimum of two hours should be given for there a positive effect of IPC on performance, and this effect remains at least eight hours. In addition, it is likely that increased glycolytic contribution, reflected by higher &#916;[Lac], may have led a greater SR and a consequent improvement in performance in D2 and D8 after IPC application.O presente estudo teve como objetivo verificar os efeitos do pré-condicionamento isquêmico (PCI) sobre o desempenho de 50 metros, nas variáveis técnicas e no lactato sanguíneo. Dez nadadores federados (20 ± 3 anos, 1,82 ± 0,05 m, 77 ± 5 kg e 24,79 ± 1,04 segundos nos 50 metros livres) participaram de um delineamento de medidas repetidas. O protocolo foi composto por três visitas, sendo a primeira uma avaliação antropométrica, a segunda e a terceira (em ordem randômica) a três subsequentes desempenhos de 50 metros em piscina olímpica, sendo o primeiro à uma hora (D1), o segundo a duas (D2) horas e o terceiro a oito horas (D8) após aplicação do PCI ou condição controle (CTRL). Além da medida de desempenho, foi mensurada a diferença (&#916;[Lac]) do lactato pico pós exercício do pré exercício de cada desempenho. Além disso, os índices técnicos referentes ao comprimento de braçada (CB), frequência de braçada (FB) e índice de braçada (IB) foram mensurados durante três trechos na fase de nado. PCI apresentou um efeito médio de 0,85 % de melhora no desempenho. Embora o efeito não tenha sido significativo em D1 (0,37 %; p = 0,25), em D2 e D8 houve um claro efeito do tratamento (1,02 % e 1,18 %; p < 0,01, respectivamente). Ainda, os dados de melhora no desempenho foram acompanhados por um maior &#916;[Lac] em D2 (PCI: 9,04 vs CTRL: 7,77 mmol/L; p < 0,01) e em D8 (PCI: 9,55 vs CTRL: 8,52 mmol/L; p = 0,05), como também, a análise por trechos dos índices técnicos permitiu identificar um maior comportamento da FB em D2 e em D8. Com base nestes resultados, pode-se sugerir que um intervalo mínimo de duas horas seja dado para que haja um efeito do PCI no desempenho, sendo que esse efeito perdura por pelo menos 8 horas. Além disso, é provável que uma maior contribuição glicolítica, refletida pelo maior &#916;[Lac], possa ter levado a uma maior FB e consequente melhora no desempenho em D2 e D8 após aplicação do PCI.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

A fast-start pacing strategy speeds pulmonary oxygen uptake kinetics and improves supramaximal running performance.

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

The V̇O₂ responses and blood parameters during the 1-min all-out test for sprinters (SPRs) and endurance runners (ENDs).

<p>V̇O₂peak was determined as the 15-s rolling average; tV̇O₂peak is the time to achieve V̇O₂peak; V̇O₂ decrease is the difference between the V̇O₂ value at 30 s and the end-exercise V̇O₂; O₂ consumed was determined as the time integral above the V̇O₂rest for the 5-s V̇O₂ values; ∆BLC and ∆pH is the difference between pre test and peak exercise values of blood lactate concentration and pH, respectively.</p><p>*Significant difference between groups (<i>p</i> < 0.05)</p><p>The V̇O₂ responses and blood parameters during the 1-min all-out test for sprinters (SPRs) and endurance runners (ENDs).</p

Pulmonary V̇O₂ response during the 110%MAV test for group mean data (a,b) and for a representative subject in each group (c).

<p>VO₂ was expressed in absolute and relative terms (%VO₂max) in Fig 1A and 1B, respectively. In Fig 1A and 1B, data were matched at the shortest time to exhaustion recorded in each group. Moreover, the mean ± SD of the asymptote (i.e. amplitude + V̇O₂ rest) and time to exhaustion are also shown. In Fig 1C, the exponential fits of the data and the residuals were also illustrated.</p

Time course of the V̇O₂ during the 1 min all-out running test in sprinters and endurance runners.

<p>VO₂ was expressed in relative (%VO₂max) and absolute terms in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133785#pone.0133785.g001" target="_blank">Fig 1A and 1B</a>, respectively. Statistical analysis was only performed on relative terms. ^asignificant difference between groups (<i>p</i> < 0.05); ^a*statistical trend for a higher V̇O₂ in sprinters (<i>p</i> = 0.09); ^bV̇O₂ significantly higher than end-exercise V̇O₂ in sprinters (<i>p</i> < 0.05).</p

The mean ± SD of the incremental test data and performance parameters during 1 MT for sprinters (SPRs) and endurance runners (ENDs).

<p>MAV, maximal aerobic velocity; V̇O₂max, maximum oxygen uptake; V_max and V_mean, maximum and mean velocity during 1-min all-out.</p><p>* significant difference between groups (<i>p</i> < 0.001).</p><p>The mean ± SD of the incremental test data and performance parameters during 1 MT for sprinters (SPRs) and endurance runners (ENDs).</p