Reliability of Repeated Sprint Exercise in Non-Motorised Treadmill Ergometry

Intra-Session Reliability of Sprint Performance on a Non-Motorised Treadmill for Healthy Active Males and Females

This study examined the intra-session reliability of sprint performance on a non-motorized treadmill amongst healthy, active male and female adults. One hundred and twenty participants (males n = 77; females n = 45) completed two familiarization sessions, followed by a third session that consisted of three trials (T1, T2, T3) of maximal sprints (4-s), interspersed by three minutes of recovery. Combining males and females exhibited moderate-to-excellent test-retest reliability (intra-class correlation coefficient, ICC), minimal measurement error (coefficient of variation, CV) and trivial differences between trials (effect size, ES) for speed, power, total work and acceleration (ICC = 0.82-0.98, CV = 1.31-8.45%, ES = 0.01-0.22). The measurement error was improved between comparisons of T1 vs. T2 (CV = 1.62-8.45%, ES = 0.12-0.22) to T2 vs. T3 (CV = 1.31-6.56%, ES = 0.01-0.07) and better for females (CV = 1.26-7.94%, ES = 0.001-0.26) than males (CV = 1.33-8.53%, ES = 0.06-0.31). The current study demonstrated moderate-to-excellent reliability and good-moderate measurement error during a 4-s sprint on a non-motorized treadmill. However, sex had a substantial impact with females exhibiting better values. Practitioners should employ at least two separate trials within a session, in addition to multiple familiarization sessions, to achieve reliable non-motorized treadmill sprint performances.

Transcranial Direct Current Stimulation Decreases the Decline of Speed during Repeated Sprinting in Basketball Athletes

The purpose of this study was to determine whether transcranial direct current stimulation (tDCS) can improve countermovement jump performance, fatigue index and alleviate the speed decline during repeated shuttle sprints in trained basketball players. Thirteen trained basketball players were divided into the tDCS trial and sham trial by the random crossover design. The tDCS trial was stimulated with 2-mA current in the M1 area in the middle of the top of the head for 20 min. For the sham trial, the current was turned off after 5 s, stopping the electrical stimulation. After warming up, the players underwent countermovement jump test, weighted countermovement jump test and then performed 40 × 15-m sprints with with a 1:4 exercise: rest ratio. The jump height, sprinting time, fatigue index, heart rate and rating of perceived exertion (RPE) were analyzed by paired-sample t-test, when significance was discovered by two-way repeated measures analysis of variance. The study results revealed that the tDCS trial significantly increase the countermovement jump performance (p = 0.04), decrease the sprinting time (p = 0.016), and had improved fatigue index during the sprinting process (p = 0.009). However, the heart rate and RPE during sprinting were nonsignificantly different between the trials. This study has identified that tDCS can decrease the speed decline, fatigue index during sprinting and increase countermovement jump performance without affecting heart rate or the rating of perceived exertion.

Fatigue Indices and Perceived Exertion Highlight Ergometer Specificity for Repeated Sprint Ability Testing

This study aimed to compare the time course of measures of performance, fatigue, and perceived exertion during repeated-sprint ability (RSA) testing performed on a non-motorized treadmill (NMT) and cycling ergometer (CE). Fourteen physically active participants performed two 10 ×6 s⁻¹ RSA tests with a 1:4 work-to-rest ratio (24 s recovery) on NMT and CE. Measures of performance [peak and mean power output (PPO and MPO), cadence, and the time to reach PPO (TTP)] and of fatigue (fatigue index and decrement score) and ratings of perceived exertion (RPE) were collected during each session. The level of significance was set at p < 0.05. Participants completed the RSA test at a MPO of 1,041 ± 141 W on CE and 431 ± 48 W on NMT, achieving PPO of 2,310 ± 339 W on CE and 1,763 ± 289 W on NMT. Participants' weight was significantly correlated with PPO and MPO on CE (p < 0.001) and with MPO on NMT (p < 0.001). PPO on CE and NMT was significantly correlated only for absolute measures of power (p < 0.01). Cadence was higher and decreased throughout the RSA on NMT compared to CE, where it decreased only at the seventh bout. TTP was significantly shorter and more affected by fatigue on NMT than on CE. Fatigue indices were significantly greater on NMT compared to CE, with significant correlations between the decrement score and absolute and relative PPO on CE and NMT, between the fatigue index and absolute and relative PPO only on NMT, and no significant correlations with MPO. During RSA, RPE increased more on NMT compared to CE from bouts 3 to 7. During recovery, RPE was consistently higher on NMT at 1, 3, and 5 min post exercise compared to CE. These findings indicate that RSA performed on NMT induces greater fatigue and physiological load than CE, which originated in the lower resistive torque typically used on NMT compared to CE, resulting in a front loaded power output profile from the greater acceleration and cadence. From these results, we discuss that despite providing highly correlated measures of power output, NMT and CE should not be used interchangeably to assess RSA as they elicit markedly different responses. We also discuss these results from the fundamental differences in active muscle mass and power application patterns between running and cycling, which could form the basis of future studies.

Sprint running kinematics and kinetics in pre-peak-height-velocity male children on a non-motorised treadmill: reliability and normative data

The purpose of this study was to quantify the reliability of kinematic and kinetic variables using a sample of pre-peak-height-velocity (PHV) male athletes sprinting on a non-motorised treadmill. Following variables were measured and their normative data presented, average and peak velocity, average and peak power, average and peak horizontal force, average and peak vertical force, average step frequency, average step length, average work. Twenty-five participants performed three 5-s all-out sprints from a standing split start on a non-motorised treadmill on three separate occasions. Per cent change in the means (-3.66 to 3.35%) and coefficients of variation (0.56-7.81%) were thought reliable for all variables. However, average step rate, average horizontal force and average vertical force did not meet the standards (≥0.70) set for acceptable intraclass correlation coefficients (ICC). Due to the homogeneous group, it was expected to receive low ICC values. Therefore, youth sprinting performance can be tested reliably on a non-motorised treadmill, especially if the per cent change in the mean and CV are deemed the important reliability measures. Normative data are given for the participant's age as well as their maturity level for kinematic and kinetic variables.

Power, fatigue, and recovery changes in national collegiate athletic association division I hockey players across a competitive season

This study aimed to evaluate changes in pre- to postseason power output, fatigue, and recovery during a repeated sprint test. Twenty National Collegiate Athletic Association Division I men's hockey athletes performed identical sessions of repeated sprint work pre- and postseason. The repeated sprint test consisted of 5 sets of 45 seconds of repeated sprint work with 90 seconds of rest in between each series of sprints. Power output (W), decrement, and recovery scores (RECs) were determined using raw data from a nonmotorized treadmill. Ratings of perceived exertion were recorded after, and perceived readiness (PR) recorded before, each series of sprints. Mean power was significantly higher in preseason vs. postseason performance during sprint 1 (760.6 vs. 691.3 W; p = 0.03), sprint 2 (719.9 vs 657.0 W; p = 0.05), sprint 4 (648.4 vs 588.9 W; p = 0.04), and sprint 5 (656.6 vs. 586.8 W, p = 0.04). Ratings of perceived exertion were significantly higher during sprints 3, 4, and 5 postseason with PR significantly higher (indicating less readiness) before sprints 3 and 4. There were no significant differences in REC or decrement score. Overall, athletes were unable to maintain power during subsequent repeated sprint work during postseason. The degree to which the athletes fatigued and recovered between sprints did not change between pre- and postseason testing, however, athletes exhibit increased perceptual strain during the repeated sprint work. These data indicate meaningful performance and perceptual differences throughout the competitive season in collegiate-level hockey players.

Markers for Routine Assessment of Fatigue and Recovery in Male and Female Team Sport Athletes during High-Intensity Interval Training

Aim

Our study aimed to investigate changes of different markers for routine assessment of fatigue and recovery in response to high-intensity interval training (HIIT).

Methods

22 well-trained male and female team sport athletes (age, 23.0 ± 2.7 years; V̇O_2max, 57.6 ± 8.6 mL·min·kg⁻¹) participated in a six-day running-based HIIT-microcycle with a total of eleven HIIT sessions. Repeated sprint ability (RSA; criterion measure of fatigue and recovery), countermovement jump (CMJ) height, jump efficiency in a multiple rebound jump test (MRJ), 20-m sprint performance, muscle contractile properties, serum concentrations of creatinkinase (CK), c-reactive protein (CRP) and urea as well as perceived muscle soreness (DOMS) were measured pre and post the training program as well as after 72 h of recovery.

Results

Following the microcycle significant changes (p < 0.05) in RSA as well as in CMJ and MRJ performance could be observed, showing a decline (%Δ ± 90% confidence limits, ES = effect size; RSA: -3.8 ± 1.0, ES = -1.51; CMJ: 8.4 ± 2.9, ES = -1.35; MRJ: 17.4 ± 4.5, ES = -1.60) and a return to baseline level (RSA: 2.8 ± 2.6, ES = 0.53; CMJ: 4.1 ± 2.9, ES = 0.68; MRJ: 6.5 ± 4.5, ES = 0.63) after 72 h of recovery. Athletes also demonstrated significant changes (p < 0.05) in muscle contractile properties, CK, and DOMS following the training program and after the recovery period. In contrast, CRP and urea remained unchanged throughout the study. Further analysis revealed that the accuracy of markers for assessment of fatigue and recovery in comparison to RSA derived from a contingency table was insufficient. Multiple regression analysis also showed no correlations between changes in RSA and any of the markers.

Conclusions

Mean changes in measures of neuromuscular function, CK and DOMS are related to HIIT induced fatigue and subsequent recovery. However, low accuracy of a single or combined use of these markers requires the verification of their applicability on an individual basis.

Complex network models reveal correlations among network metrics, exercise intensity and role of body changes in the fatigue process

The aims of the present study were analyze the fatigue process at distinct intensity efforts and to investigate its occurrence as interactions at distinct body changes during exercise, using complex network models. For this, participants were submitted to four different running intensities until exhaustion, accomplished in a non-motorized treadmill using a tethered system. The intensities were selected according to critical power model. Mechanical (force, peak power, mean power, velocity and work) and physiological related parameters (heart rate, blood lactate, time until peak blood lactate concentration (lactate time), lean mass, anaerobic and aerobic capacities) and IPAQ score were obtained during exercises and it was used to construction of four complex network models. Such models have both, theoretical and mathematical value, and enables us to perceive new insights that go beyond conventional analysis. From these, we ranked the influences of each node at the fatigue process. Our results shows that nodes, links and network metrics are sensibility according to increase of efforts intensities, been the velocity a key factor to exercise maintenance at models/intensities 1 and 2 (higher time efforts) and force and power at models 3 and 4, highlighting mechanical variables in the exhaustion occurrence and even training prescription applications.

Is there a diurnal variation in repeated sprint ability on a non-motorised treadmill?

In active males, muscle force production and short-term (<6 s) anaerobic performance are significantly greater in the evening compared with the morning. This diurnal variation is attributed to motivational, peripheral and central factors, and possibly the higher core and muscle temperatures observed in the evening. However, little is known regarding whether diurnal variation on a treadmill also exists in team-sport specific tests of repeated sprint ability (RSA), as would be relevant to football, for example. A controlled laboratory protocol using a non-motorised treadmill has been used to investigate whether daily variation in RSA is present in highly motivated athletes. Twenty active males (mean ± SD: age, 21.0 ± 2.2 yrs; maximal oxygen uptake ([Formula: see text] max), 60.8 ± 4.8 ml kg min(-1); body mass, 77.02 ± 10.5 kg and height, 1.79 ± 0.07 m) volunteered and completed two sessions counterbalanced in order of administration (separated by >48 h): a morning (M, 07:30 h) and evening (E, 17:30 h) session. Both sessions included a 5-min active warm-up on a motorised treadmill at 10 km h(-1) followed by three task-specific warm-up sprints at 50%, 70% and 80%, respectively, on a non-motorised treadmill. During each trial, 10 × 3 s repeated sprints with 30 s recoveries were performed on the non-motorised treadmill. Rectal (Trec) and muscle temperature measurements (Tm) were taken after subjects had reclined for 30 min at the start of the protocol, and again after the active warm-up. Values of heart rate, thermal comfort (TC), rating of perceived exertion (RPE) and effort were measured throughout. Blood samples were taken at rest, after the sprints and 5-min post sprints. Data were analysed using a GLM with repeated measures. Trec and Tm values were higher at rest in the evening than the morning (0.46 °C and 0.57 °C, respectively, p < 0.05). Distance covered, peak power, average power, peak velocity and average velocity all showed significantly higher values in the evening compared with the morning (a range of 3.3-8.3%, p < 0.05), with peak power displaying a statistical trend (0.10 > p > 0.05). All subjects reported maximal values for "effort" for each sprint. There were significant positive correlations between Trec and Tm, Trec and RPE, TC and all measures of RSA performance. However, there was no correlation between fatigue index for peak power output or peak velocity and Trec. In summary, in this population of motivated subjects, time-of-day effects were seen in resting Trec and Tm values and all performance measures of RSA, in partial agreement with past research. The diurnal variation in Trec and Tm cannot fully explain time-of-day oscillations in RSA on a non-motorised treadmill. Although central temperature may provide some endogenous rhythm to human performance, the causal link seems to be due to a multiplicity of components and mechanisms.

Sodium bicarbonate supplementation and ingestion timing: does it matter?

Although a considerable amount of literature exists on the ergogenic potential of ingesting sodium bicarbonate (NaHCO3) before short-term, high-intensity exercise, very little exists on optimal loading times before exercise. The purpose of this study was to determine the influence of NaHCO3 supplementation timing on repeated sprint ability (RSA). Eight men completed 3 (randomized and counterbalanced) trials of ten 10-second sprints separated by 50 seconds of active recovery (1:5 work-to-rest) on a nonmotorized treadmill. Before each trial, the subjects ingested 0.3 g·kg(-1) body weight of NaHCO3 at 60 (H1), 120 (H2), or 180 (H3) minutes before exercise. Additionally, the subjects were assessed for any side effects (gastrointestinal [GI] discomfort) from the NaHCO3 ingestion via a visual analog scale (VAS). Blood buffering was assessed using a 2-way analysis of variance (ANOVA) with repeated measures, whereas repeated sprint performance and GI discomfort were assessed via a 1-way ANOVA with repeated measures. Blood-buffering capacity was not different at preexercise times (HCO3(-) [millimoles per liter] H1: 30.2 ± 0.4, H2: 30.9 ± 0.6, H3: 31.2 ± 0.6; p > 0.74). Average speed, average power, and total distance covered progressively declined over the 10 sprints; however, there was no difference between conditions (p > 0.22). The incidence of GI discomfort was significantly higher (p < 0.05) from preingestion at all time points with the exception of 180 minutes, whereas severity was only different between 90 and 180 minutes. Ingestion times (between 60 and 180 minutes) did not influence the blood buffering or the ergogenic potential of NaHCO3 as assessed by RSA. However, VAS scores indicated that at 180 minutes postingestion, an individual is less prone to experiencing significant GI discomfort.

The effects of a constant sprint-to-rest ratio and recovery mode on repeated sprint performance

It is unclear if a constant sprint-to-rest ratio allows full performance recovery between repeated sprints over different distances. This is important for the development of sprint-training programs. Additionally, there is conflicting evidence on whether active recovery enhances sprint performance. Three repeated sprint protocols were used (22 × 15, 13 × 30, and 8 × 50 m), with each having an active and passive recovery. Each trial was conducted with an initial sprint-to-rest ratio of 1:10. Repeated sprints were analyzed by comparing the first sprint to the last sprint. For the 15-m trials, there were no significant main effects for recovery or time and no significant interaction. For the 30-m trials, there was no main effect for recovery, but a main effect for time (F[1,10] = 15.995, p = 0.003; mean difference = 0.20 seconds, 95% confidence interval [CI] = 0.09-0.31 seconds, d = 1.4 [large effect]). There was no interaction of recovery and time in the 30-m trials. For the 50-m trials, there was no main effect for recovery, but a main effect for time (F[1,10] = 34.225, p = 0.0002; mean difference = 0.39 seconds, 95% CI = 0.24-0.55 seconds, d = 1.3 [large effect]). There was no interaction of recovery and time in the 50-m trials. The results demonstrate that a 1:10 sprint-to-rest ratio allows full performance recovery between 15-m sprints, but not between sprints of 30 or 50 m, and that recovery mode did not influence repeated sprint performance.

Menstrual cycle and oral contraceptives' effects on growth hormone response to sprinting

The present study examined the impact of the menstrual cycle and oral contraceptive (OC) use on the growth hormone response to non-motorized treadmill sprinting. Nine monophasic OC users (21.5 ± 4.7 years old), and 8 normally menstruating women (NM; 21.4 ± 2.9 years old) participated in the study. Each participant completed 2 main trials, each consisting of an all-out 30-s treadmill sprint. The NM group performed one trial in the midfollicular phase (NM follicular) and one in the midluteal phase (NM luteal); the OC group's trials occurred one week into the start of the pill-taking cycle and once during the week in which pills were not taken.Venous blood samples were analyzed for growth hormone, pH, lactate, glucose, and progesterone concentrations. Peak and mean power output did not differ between the groups or with menstrual phase, or between the OC-free and OC trials. Integrated growth hormone was greater in the OC group than in the NM group (p = 0.04) with no phase difference (p = 0.80, mean (SD); NM follicular: 421 (335) and NM luteal: 345 (304) vs. OC free: 737 (471) and OC: 758 (389) µg·L(-1)·90 min(-1)). Blood lactate was higher in the OC group than in the NM group (p = 0.007) and, conversely, pH was lower in the OC group (p = 0.01). These results demonstrate that OC users who take high-androgenicity pills have a higher growth hormone response to sprint running than do normally menstruating women.

A return-to-sport algorithm for acute hamstring injuries

Acute hamstring injuries are the most prevalent muscle injuries reported in sport. Despite a thorough and concentrated effort to prevent and rehabilitate hamstring injuries, injury occurrence and re-injury rates have not improved over the past 28 years. This failure is most likely due to the following: 1) an over-reliance on treating the symptoms of injury, such as subjective measures of "pain", with drugs and interventions; 2) the risk factors investigated for hamstring injuries have not been related to the actual movements that cause hamstring injuries i.e. not functional; and, 3) a multi-factorial approach to assessment and treatment has not been utilized. The purpose of this clinical commentary is to introduce a model for progression through a return-to-sport rehabilitation following an acute hamstring injury. This model is developed from objective and quantifiable tests (i.e. clinical and functional tests) that are structured into a step-by-step algorithm. In addition, each step in the algorithm includes a treatment protocol. These protocols are meant to help the athlete to improve through each phase safely so that they can achieve the desired goals and progress through the algorithm and back to their chosen sport. We hope that this algorithm can serve as a foundation for future evidence based research and aid in the development of new objective and quantifiable testing methods.

The reliability and validity of fatigue measures during multiple-sprint work: an issue revisited

The ability to repeatedly produce a high-power output or sprint speed is a key fitness component of most field and court sports. The aim of this study was to evaluate the validity and reliability of eight different approaches to quantify this parameter in tests of multiple-sprint performance. Ten physically active men completed two trials of each of two multiple-sprint running protocols with contrasting recovery periods. Protocol 1 consisted of 12 x 30-m sprints repeated every 35 seconds; protocol 2 consisted of 12 x 30-m sprints repeated every 65 seconds. All testing was performed in an indoor sports facility, and sprint times were recorded using twin-beam photocells. All but one of the formulae showed good construct validity, as evidenced by similar within-protocol fatigue scores. However, the assumptions on which many of the formulae were based, combined with poor or inconsistent test-retest reliability (coefficient of variation range: 0.8-145.7%; intraclass correlation coefficient range: 0.09-0.75), suggested many problems regarding logical validity. In line with previous research, the results support the percentage decrement calculation as the most valid and reliable method of quantifying fatigue in tests of multiple-sprint performance.

The reliability of physiological and performance measures during simulated team-sport running on a non-motorised treadmill

The aim of this study was to determine the reliability of a non-motorised treadmill team-sport simulation for measuring physiological responses and performance demands of team sports. Following familiarisation, 11 team-sport athletes completed a peak sprinting speed assessment followed by a 30-min team-sport simulation on the non-motorised treadmill, on three occasions, 5 days apart. Several performance (total distance, distance covered during each speed category, total work, high-intensity activity, mean maximal sprinting speed and power) and physiological variables (V(O)(2), heart rate and blood measures) were measured. A one-way analysis of variance and ratio limits of agreement were used to compare the results from each trial. Significant differences were established in total sprint distance and high-intensity activity between trials 1-2 and trials 1-3 and 3-s mean maximal sprinting speed for trials 1-3 (p<0.05). No other significant differences were identified. Moderate to high intraclass correlation coefficients (i.e., >0.8) were identified in 11 of the 18 physiological and performance variables measured. Ratio limits of agreement for total distance covered and total work performed during the team-sport simulation were 0.99 (*//1.05) and 0.97 (*//1.09), respectively. Largest measurement error was shown in post-exercise blood lactate concentration with a coefficient of variation of 17.6%. All other measures showed low coefficients of variation of < or = 10%. These results show that the non-motorised treadmill team-sport simulation provides a reliable tool for assessing and monitoring physiological and performance demands of team-sport activity. We recommend the inclusion of two familiarisation sessions prior to testing.

Multiple-Sprint Work: Methodological, Physiological, and Experimental Issues

Tests of repeated-sprint ability provide a simple way to evaluate the basic physical characteristics of speed and endurance necessary to excel in various multiple-sprint sports. Furthermore, such tests help overcome the complications associated with field-based evaluations of this type of exercise. Nevertheless, despite over 40 y of research, many issues regarding our understanding of multiple-sprint work remain unresolved. This commentary aims to raise awareness of issues relating to methodology, physiological responses, and the effectiveness of various ergogenic and training strategies; to promote a greater understanding; and to drive future research.

Is a fatigue index a worthwhile measure of repeated sprint ability?

The purpose of this opinion piece is to consider the usefulness of fatigue measures when describing performance in repeated sprint tests. The reliability of different methods of calculating fatigue is discussed and an explanation for the large variability explained. Essentially the mathematical procedures involved in calculating fatigue levels from a small drop-off in performance will always result in an unreliable measure. Consequently, the use of a fatigue index or percentage decrement score to describe repeated sprint ability may be questioned.