Reliability and Validity of Predicted Performance in the Severe-Intensity Domain From the 3-Minute All-Out Running Test.

PURPOSE: The aim of this study was to analyze the reliability and validity of the predicted distance-time relationship in the severe-intensity domain from a 3-minute all-out running test (3MT). METHODS: Twelve runners performed two 3MTs (test #1 and test #2) on an outdoor 400-m track after familiarization. Eighteen-hertz Global Positioning System data were used to estimate critical speed (CS) and distance covered above CS (D'). Time to cover 1200 and 3600 m (T1200 and T3600, respectively) was predicted using CS and D' estimates from each 3MT. Eight runners performed 2 time trials in a single visit to assess real T1200 and T3600. Intraclass correlation coefficients (ICCs) and standard errors of measurement were calculated for reliability analysis. RESULTS: Good to excellent reliability was found for CS, T1200, and T3600 estimates from 3MT (ICC > .95, standard error of measurement between 1.3% and 2.2%), and poor reliability was found for D' (ICC = .55, standard error of measurement = 27%). Predictions from 3MT were significantly correlated to actual T1200 (r = .87 and .85 for test #1 and test #2, respectively) and T3600 (r = .91 and .82 for test #1 and test #2, respectively). The calculation of error prediction showed a systematic error between predicted and real T3600 (6.4% and 7.8% for test #1 and test #2, respectively, P < .01) contrary to T1200 (P > .1). Random error was between 4.4% and 6.1% for both distances. CONCLUSIONS: Despite low reliability of D', 3MT yielded a reliable predicted distance-time relationship allowing repeated measures to evidence change with training adaptation. However, caution should be taken with prediction of performance potential of a single individual because of substantial random error and significant underestimation of T3600.

Impact of systemic hypoxia and blood flow restriction on mechanical, cardiorespiratory, and neuromuscular responses to a multiple-set repeated sprint exercise.

Introduction: Repeated sprint cycling exercises (RSE) performed under systemic normobaric hypoxia (HYP) or with blood flow restriction (BFR) are of growing interest. To the best of our knowledge, there is no stringent consensus on the cardiorespiratory and neuromuscular responses between systemic HYP and BFR during RSE. Thus, this study assessed cardiorespiratory and neuromuscular responses to multiple sets of RSE under HYP or with BFR. Methods: According to a crossover design, fifteen men completed RSE (three sets of five 10-s sprints with 20 s of recovery) in normoxia (NOR), HYP, and with bilaterally-cuffed BFR at 45% of resting arterial occlusive pressure during sets in NOR. Power output, cardiorespiratory and neuromuscular responses were assessed. Results: Average peak and mean powers were lower in BFR (dz = 0.87 and dz = 1.23, respectively) and HYP (dz = 0.65 and dz = 1.21, respectively) compared to NOR (p < 0.001). The percentage decrement of power output was greater in BFR (dz = 0.94) and HYP (dz = 0.64) compared to NOR (p < 0.001), as well as in BFR compared to NOR (p = 0.037, dz = 0.30). The percentage decrease of maximal voluntary contraction of the knee extensors after the session was greater in BFR compared to NOR and HYP (p = 0.011, dz = 0.78 and p = 0.027, dz = 0.75, respectively). Accumulated ventilation during exercise was higher in HYP and lower in BFR (p = 0.002, dz = 0.51, and p < 0.001, dz = 0.71, respectively). Peak oxygen consumption was reduced in HYP (p < 0.001, dz = 1.47). Heart rate was lower in BFR during exercise and recovery (p < 0.001, dz = 0.82 and p = 0.012, dz = 0.43, respectively). Finally, aerobic contribution was reduced in HYP compared to NOR (p = 0.002, dz = 0.46) and BFR (p = 0.005, dz = 0.33). Discussion: Thus, this study indicates that power output during RSE is impaired in HYP and BFR and that BFR amplifies neuromuscular fatigue. In contrast, HYP did not impair neuromuscular function but enhanced the ventilatory response along with reduced oxygen consumption.

Cardiorespiratory and Neuromuscular Improvements Plateau after 2 wk of Sprint Interval Training in Sedentary Individuals.

INTRODUCTION: Previous studies ranging from 2 to 12 wk of sprint interval training (SIT) have reported improvements in maximal oxygen uptake (V̇O 2max ) and neuromuscular function in sedentary populations. However, whether the time course of the changes in these variables correlates with greater training volumes is unclear. METHODS: Thirteen sedentary participants performed three all-out training weekly sessions involving 15-s sprints interspersed with 2 min of recovery on a cycle ergometer. The 6-wk training program was composed of three identical blocks of 2 wk in which training volume was increased from 10 to 14 repetitions over the first four sessions and reduced to 8 in the last session. The power output and the heart rate (HR) were monitored during the sessions. The V̇O 2max , the power-force-velocity profile, and the isometric force were assessed every 2 wk from baseline. RESULTS: A significant increase in V̇O 2max was observed from the second week plateauing thereafter despite four additional weeks of training. The dynamic force production increased from the second week, and the speed production decreased by the end of the protocol. The isometric force and the maximal power output from the power-force-velocity profile did not change. Importantly, the time spent at high percentages of the maximal HR during the training sessions was lower in the second and third training block compared with the first. CONCLUSIONS: SIT resulted in an effective approach for rapidly increasing V̇O 2max , and no change in the isometric force was found; cycling-specific neuromuscular adaptations were observed from the second week of training. SIT may be useful in the short term, but further improvement of overall physical fitness might need other training modalities like endurance and/or resistance training.

Neuromuscular and autonomic function is fully recovered within 24 h following a sprint interval training session.

BACKGROUND: Recovery is a key factor to promote adaptations and enhance performance. Sprint Interval Training (SIT) is known to be an effective approach to improve overall physical function and health. Although a 2-day rest period is given between SIT sessions, the time-course of recovery after SIT is unknown. PURPOSE: The aim of this study was to determine whether the neuromuscular and autonomic nervous systems would be impaired 24 and 48 h after an SIT session. METHODS: Twenty-five healthy subjects performed an 8 × 15 s all-out session on a braked cycle ergometer with 2 min of rest between repetitions. Isometric maximal voluntary contraction (iMVC) and evoked forces to electrical nerve stimulation during iMVC and at rest were used to assess muscle contractile properties and voluntary activation before (Pre), 1 (Post24h), and 2 (Post48h) days after the session. Two maximal 7 s sprints with two different loads were performed at those same time-points to evaluate the maximal theoretical force (F0), velocity (V0) and maximal power (Pmax) production during a dynamic exercise. Additionally, nocturnal heart rate variability (HRV) was assessed the previous and the three subsequent nights to the exercise bout. RESULTS: No significant impairments were observed for the iMVC or for the force evoked by electrical stimulation 1 day after the session. Similarly, F0, V0, and Pmax were unchanged at Post24h and Post48h. Furthermore, HRV did not reveal any temporal or frequential significant difference the nights following SIT compared to Pre. CONCLUSION: The results of this study show a full recovery of neuromuscular and autonomic functions a day after an all-out SIT session.

Changes in power-force-velocity profile induced by 2 weeks of sprint interval training.

BACKGROUND: This study aimed to determine the effects of a running sprint interval training protocol (R-SIT) on the sprint acceleration mechanical properties and jump performance. Eleven young male basketball players performed 6 R-SIT sessions for 2 weeks. METHODS: Each session consisted of 30-second running bouts repeated 4 to 7 times interspersed by 4 minutes of recovery. Performance was assessed from the individual power-force-velocity profiles (PVFP) over a 20-m sprint and from a countermovement jump at baseline (PRE) and after two weeks of training (POST). RESULTS: Sprint time decreased by 2% over the first 5 and 10 meters (P<0.01) while no significant changes in the time at 20 meters (-0.8%, P=0.09) nor in maximal velocity (-1%, P=0.31) were detected. The average PFVP showed an increase in theoretical maximal force and power output of 5 and 4%, respectively (P<0.05), with no change in theoretical maximal speed (P=0.26). Jump height and power also increased after training (5 and 3% respectively, P<0.01). Players improved their maximal sprint distance covered during the 30-second bouts and became more fatigue-resistant to long sprint events. CONCLUSIONS: Six sessions of R-SIT helped to enhance short sprint times, acceleration and power output.

Effects of Three Preseason Training Programs on Speed, Change-of-Direction, and Endurance in Recreationally Trained Soccer Players.

Background: Modern coaches experience a drastic reduction of the available training time with an increasingly large number of competitions during the competitive season. Thus, they must choose wisely the most efficient methods to improve the physical fitness of their players during the preseason. Among all the methods, this study compared the effects of plyometric training (PT), sprint interval training (SIT), and small-sided games (SSGs) on the performance of recreationally trained soccer players. Methods: Seventy-three participants were randomly assigned in one of the three experimental groups (i.e., PT [n = 23], SIT [n = 26] or SSGs [n = 24]) and completed two sessions per week for a total of 3 weeks. Meanwhile, the whole group maintained their habitual soccer-specific training program who do not interfere in the preparation of the season. Repeated sprint ability (RSA), maximal aerobic speed (MAS), and a 30-m sprint were assessed at baseline (PRE) and post-training (POST). Results: Performance in SSGs decreased for the average speed from 0 to 10 m (V 0-10m; -0.84 km h-1, -4 ± 5%, p < 0.001), the maximal distance (D max) covered in the 30-s RSA test (-3.65 m, -3 ± 6%, p < 0.01) and MAS (-0.52 km h-1, -3 ± 6%, p < 0.01). PT increased the mean distance (D mean) covered in the 30-s RSA test (+5.98 m, 5 ± 4%, p < 0.001) and MAS (+0.58 km h-1, 7 ± 5%, p < 0.01) while an improvement of all parameters but the maximal sprint speed reached during the 30-m trip (V max) was found in the SIT group (V 0-10m: +1.462 km h-1, 8 ± 5%, p < 0.001; D max: +7.89 m, 6 ± 5%, p < 0.001; D mean: +8.69 m, 7 ± 5%, p < 0.001 and MAS: +1.74 km h-1, 12 ± 8%, p < 0.001). All SSG POST values were significantly lower than PT and SIT (p < 0.01). D mean and MAS in POST were also significantly higher in SIT than in the PT group (p < 0.001). Conclusion: This study suggests that both PT and SIT could be a better alternative to SSGs to boost performances during preseason. Moreover, SIT seems to produce higher improvements in physical performances than PT.