Physiological responses to shuttle repeated-sprint running

Metabolic, cognitive and neuromuscular responses to different multidirectional agility-like sprint protocols in elite female soccer players - a randomised crossover study

PURPOSE

Resistance to fatigue is a key factor in injury prevention that needs to be considered in return-to-sport (RTS) scenarios, especially after severe knee ligament injuries. Fatigue should be induced under game-like conditions. The SpeedCourt (SC) is a movement platform for assessing multidirectional sprint performance, typical of game-sports, due to change-of-direction movements in response to a visual stimulus. Designing adequate fatigue protocols requires the suitable arrangement of several loading variables such as number of intervals, sprint distance or work/relief ratio (W:R). Therefore, this study analysed the acute fatigue effects of different SC protocols on metabolic load, cognitive function and neuromuscular performance.

METHODS

Eighteen female soccer players (mean ± SD; age: 23.1 ± 4.6 years) of the 1st German Division participated in this randomised, crossover study. Using a random allocation sequence, players completed four volume-equated protocols differing in W:R and sprint distance per interval (P1:12 × 30 m, W:R = 1:2 s; P2:12 × 30 m, W:R = 1:3 s; P3:18 × 20 m, W:R = 1:2 s; P4:18 × 20 m, W:R = 1:3 s). Pre- and post-exercise, metabolic load was measured per blood lactate concentration (BLaC), cognitive function per reaction time (RT), and neuromuscular performance including multiple rebound jumps (MRJ height, primary outcome variable; Reactive Strength Index, RSI) and 5 m sprint times (SP5).

RESULTS

Repeated-measures ANOVA revealed significant main time effects (p < .05) with improved performance post-exercise in RT (504 vs. 482 ms, d = 1.95), MRJ height (24.0 vs. 24.8 cm, d = 0.77), RSI (1.39 vs. 1.43, d = 0.52), and SP5 (1.19 vs. 1.17 s, d = 0.56). There was significant main time (p < .001) and time x protocol interaction effects in BLaC (p < .001). P1 induced higher BLaC values (4.52 ± 1.83 mmol/L) compared to P2 (3.79 ± 1.83 mmol/L; d = 0.74) and P4 (3.12 ± 1.83 mmol/L; d = 1.06), whereas P3 (4.23 ± 1.69 mmol/L) elicited higher BLaC values compared to P4 (d = 0.74).

CONCLUSION

All protocols caused an improved cognitive function and neuromuscular performance. The former may be related to enhanced noradrenergic activation or exercise specificity which induced an improved stimulus processing. The latter may be explained by a possible post-activation performance enhancement effect on jump and sprint performance. A shorter relief duration in W:R as opposed to sprint distance per interval produced higher BLaC values. The protocols may serve as reference data for improved RTS decision-making in elite female soccer players.

TRIAL REGISTRATION

Deutsches Register Klinischer Studien (DRKS), No.: DRKS00033496 , Registered 19. Februar 2024, Retrospectively Registered.

Predicting repeat power ability through common field assessments: is repeat power ability a unique physical quality?

Background

The repeat power ability (RPA) assessment is used to test the ability to repeatedly produce maximal ballistic efforts with an external load. The underpinning physical qualities influencing RPA are undetermined. This study aimed to gain further insight into the physical qualities that determine RPA by analysing the association between physical qualities and an assessment of RPA.

Materials and methods

Ten well-trained male field hockey players performed an RPA assessment consisting of 20 repetitions of loaded countermovement jumps (LCMJ20), with a percent decrement score of peak power output calculated. Over a two-week period, each participant performed the YoYo Intermittent Recovery Test 2 (IRT2), a repeated speed ability assessment incorporating a 180° change of direction (RSA180), a 40-meter linear speed test (40 mST), an isometric mid-thigh pull (IMTP), a countermovement jump (CMJ), and a 3-repetition maximum half squat (HS) assessment. Pearson's correlation analysis was used to determine the strength of relationships between each assessment variable and the LCMJ20. The assessment variables with the strongest relationships within each assessment were used in a stepwise multiple linear regression analysis to determine the best predictor model of LCMJ20.

Results

RSA180percent decrement score (RSA180% had a very strong, significant relationship with LCMJ20 (r = 0.736: p < 0.05). HS relative strength (HSrel) was found to have a significant and very strong, negative relationship with LCMJ20 (r =  - 0.728: p < 0.05). Stepwise multiple linear regression analysis showed RSA180 to explain 48.4% of LCMJ20 variance (Adjusted R2 = 0.484) as the only covariate included in the model.

Conclusion

The findings indicate that RSA180 as a repeated high intensity effort (RHIE) task is strongly related to LCMJ20 and is also the best predictor of LCMJ20. This may suggest that RPA can provide practitioners with information on RHIE performance. The variance between assessment methods indicates that RPA may be a distinct physical quality, future research should assess other physical capacities to better understand the factors contributing to RPA.

Can Player Tracking Devices Monitor Changes in Internal Response During Multidirectional Running?

Purpose: We examined the movement, physiological and muscle function responses to running with and without (i.e. linear) multiple directional changes to understand which measures of external demands better reflected changes in the internal response. Methods: Twelve team sport athletes completed a linear and multidirectional running trial during which movement characteristics, oxygen consumption (V ˙ O 2 ), blood lactate (B[La]) and heart rate (HR) were measured. Isometric peak torque of knee extensors and flexors was also assessed before and after each trial. Results: High speed running distance was higher during the linear trial (p < 0.001), whereas time at high metabolic power (p = 0.046), number of accelerations (p < 0.001), summated HR (p = 0.003) and B[La] (p = 0.002) were higher during the multidirectional trial. Integrated external to internal ratios of high-speed running: summated HR and high-speed running: total V ˙ O 2 were different between multidirectional and linear trials (p ≤ 0.001). Conversely, high metabolic power: summated HR and high metabolic power: total V ˙ O 2 were similar (p ≥ 0.246). Small decrements in knee flexor (p = 0.003) and extensor torque (p = 0.004) were observed after both trials. Conclusion: Time at high metabolic power better reflects the increased internal response during running with more directional changes than high speed running.

Linear and Change of Direction Repeated Sprint Ability Tests: A Systematic Review

ABSTRACT

Kyles, A, Oliver, JL, Cahill, MJ, Lloyd, RS, and Pedley, J. Linear and change of direction repeated sprint ability tests: a systematic review. J Strength Cond Res 37(8): 1703-1717, 2023-The ability to repeatedly sprint is important in many sports, but there is no established protocol for measuring repeated sprint ability (RSA). The purpose of this review was to identify overground RSA protocols previously reported in the literature and to recommend standardized protocols. A systematic review of the literature was used to identify studies that have used an RSA test, with data describing protocol design extracted. One hundred eight studies were included in the review, across which 47 unique protocols were identified. Eighteen protocols included at least one change of direction (COD), and this increased mean sprint time compared with linear RSA tests (7.26 ± 1.84 vs. 4.48 ± 1.02 seconds). There was considerable variability across protocols regarding sprint distance (20-40 m), sprint repetitions (3-15), recovery duration (10-60 seconds), recovery type (active vs. passive), and work-to-rest ratio (≤1:1.4-19.2). Separate protocols are needed for linear and COD tests, and these should reflect the brief nature of intense periods of competition and stress the ability to recover. Based on data across studies for protocol design and to ensure a demanding work-to-rest ratio, it is suggested that a linear RSA should comprise 6 × 30 m sprints separated by 15 seconds of active recovery. To provide some parity to linear tests, to keep work duration brief and to maintain a demanding work-to-rest ratio, a COD RSA should comprise 6 × 30 m shuttle sprints (15 + 15 m), providing one change of direction (180° COD), and maintaining a 15-second active recovery.

The Acute Demands of Repeated-Sprint Training on Physiological, Neuromuscular, Perceptual and Performance Outcomes in Team Sport Athletes: A Systematic Review and Meta-analysis

BACKGROUND

Repeated-sprint training (RST) involves maximal-effort, short-duration sprints (≤ 10 s) interspersed with brief recovery periods (≤ 60 s). Knowledge about the acute demands of RST and the influence of programming variables has implications for training prescription.

OBJECTIVES

To investigate the physiological, neuromuscular, perceptual and performance demands of RST, while also examining the moderating effects of programming variables (sprint modality, number of repetitions per set, sprint repetition distance, inter-repetition rest modality and inter-repetition rest duration) on these outcomes.

METHODS

The databases Pubmed, SPORTDiscus, MEDLINE and Scopus were searched for original research articles investigating overground running RST in team sport athletes ≥ 16 years. Eligible data were analysed using multi-level mixed effects meta-analysis, with meta-regression performed on outcomes with ~ 50 samples (10 per moderator) to examine the influence of programming factors. Effects were evaluated based on coverage of their confidence (compatibility) limits (CL) against elected thresholds of practical importance.

RESULTS

From 908 data samples nested within 176 studies eligible for meta-analysis, the pooled effects (± 90% CL) of RST were as follows: average heart rate (HRavg) of 163 ± 9 bpm, peak heart rate (HRpeak) of 182 ± 3 bpm, average oxygen consumption of 42.4 ± 10.1 mL·kg-1·min-1, end-set blood lactate concentration (B[La]) of 10.7 ± 0.6 mmol·L-1, deciMax session ratings of perceived exertion (sRPE) of 6.5 ± 0.5 au, average sprint time (Savg) of 5.57 ± 0.26 s, best sprint time (Sbest) of 5.52 ± 0.27 s and percentage sprint decrement (Sdec) of 5.0 ± 0.3%. When compared with a reference protocol of 6 × 30 m straight-line sprints with 20 s passive inter-repetition rest, shuttle-based sprints were associated with a substantial increase in repetition time (Savg: 1.42 ± 0.11 s, Sbest: 1.55 ± 0.13 s), whereas the effect on sRPE was trivial (0.6 ± 0.9 au). Performing two more repetitions per set had a trivial effect on HRpeak (0.8 ± 1.0 bpm), B[La] (0.3 ± 0.2 mmol·L-1), sRPE (0.2 ± 0.2 au), Savg (0.01 ± 0.03) and Sdec (0.4; ± 0.2%). Sprinting 10 m further per repetition was associated with a substantial increase in B[La] (2.7; ± 0.7 mmol·L-1) and Sdec (1.7 ± 0.4%), whereas the effect on sRPE was trivial (0.7 ± 0.6). Resting for 10 s longer between repetitions was associated with a substantial reduction in B[La] (-1.1 ± 0.5 mmol·L-1), Savg (-0.09 ± 0.06 s) and Sdec (-1.4 ± 0.4%), while the effects on HRpeak (-0.7 ± 1.8 bpm) and sRPE (-0.5 ± 0.5 au) were trivial. All other moderating effects were compatible with both trivial and substantial effects [i.e. equal coverage of the confidence interval (CI) across a trivial and a substantial region in only one direction], or inconclusive (i.e. the CI spanned across substantial and trivial regions in both positive and negative directions).

CONCLUSIONS

The physiological, neuromuscular, perceptual and performance demands of RST are substantial, with some of these outcomes moderated by the manipulation of programming variables. To amplify physiological demands and performance decrement, longer sprint distances (> 30 m) and shorter, inter-repetition rest (≤ 20 s) are recommended. Alternatively, to mitigate fatigue and enhance acute sprint performance, shorter sprint distances (e.g. 15-25 m) with longer, passive inter-repetition rest (≥ 30 s) are recommended.

Physiological Responses and Fatigue during a Repeated Shuttle-Sprint Running Test in Adolescent Schoolchildren: A Comparison between Sexes and Fatigue Calculation Methods

We examined physiological responses and fatigue in adolescent boys and girls during a repeated shuttle-sprint running test in a school setting. We also compared three calculation methods to assess fatigue during repeated sprints: the fatigue index (FI), the percent sprint decrement (Sdec), and the slope of performance decrement (SlopeD). Twenty-six adolescent students (10 girls and 16 boys, age: 15.3 ± 0.5 y) performed six 30 m sprints with a 180° change of direction at 15 m, interspersed with 10 s of recovery. Blood lactate (BL), heart rate (HR) and countermovement jump performance (CMJ) were measured before and after the sprint test. Boys achieved significantly faster sprint times (11.7% to 14.8% faster than girls in all sprints, p < 0.01), and had higher post-test BL compared with girls (14.0 ± 2.9 vs. 11.3 ± 3.2 mmol/L; p = 0.02; d = 0.93). However, all fatigue indices (FI, Sdec and SlopeD) were similar in boys and girls (FI = 11.5 ± 5.0 vs. 11.5 ± 5.0; SlopeD = 10.6 ± 4.8 vs. 14.5 ± 5.1; Sdec = 5.6 ± 2.2 vs. 7.3 ± 2.2, in boys and girls, respectively, p > 0.05 for all) and were highly correlated with each other (r = 0.86 to 0.97, p < 0.01). CMJ was higher in boys (p < 0.05), but CMJ performance dropped similarly from pre- to post-test in boys and girls (13.7 ± 7.0%, p < 0.01). In conclusion, neuromuscular fatigue during and after repeated shuttle-sprint running is similar in boys and girls, despite the faster sprint times, higher CMJ and higher BL in boys. SlopeD may be used as an alternative index to quantify fatigue during repeated shuttle-sprinting, as it takes into account performance in all sprints and may provide an average sprint-by-sprint performance drop.

The soccer season: performance variations and evolutionary trends

The physiological demands of soccer challenge the entire spectrum of the response capacity of the biological systems and fitness requirements of the players. In this review we examined variations and evolutionary trends in body composition, neuromuscular and endurance-related parameters, as well as in game-related physical parameters of professional players. Further, we explore aspects relevant for training monitoring and we reference how different training stimulus and situational variables (e.g., competition exposure) affect the physiological and performance parameters of players. Generally, improvements of small magnitude in non- (non-CMJ) and countermovement-based jumps (CMJBased) and in the sprint acceleration (ACCPhase) and maximal velocity phase (MVPhase) are observed from start of preparation phase (PPS) to beginning of competition phase (BCP). A greater magnitude of increases is observed in physiological and endurance performance measures within this period; moderate magnitude in sub-maximal intensity exercise (velocity at fixed blood lactate concentrations; V2-4mmol/l) and large magnitude in VO2max, maximal aerobic speed (MAS) and intense intermittent exercise performance (IE). In the middle of competition phase (MCP), small (CMJBased and ACCPhase), moderate (non-CMJ; MVPhase; VO2max; sub-maximal exercise) and large (MAS and IE) improvements were observed compared to PPS. In the end of competition period (ECP), CMJBased and MVPhase improve to a small extent with non-CMJ, and ACCPhase, VO2max, MAS, sub-maximal intensity exercise and IE revealing moderate increments compared to PPS. Although less investigated, there are generally observed alterations of trivial magnitude in neuromuscular and endurance-related parameters between in-season assessments; only substantial alterations are examined for IE and sub-maximal exercise performance (decrease and increase of small magnitude, respectively) from BCP to MCP and in VO2max and IE (decrements of small magnitude) from MCP to ECP. Match performance may vary during the season. Although, the variability between studies is clear for TD, VHSR and sprint, all the studies observed substantial increments in HSR between MCP and ECP. Finally, studies examining evolutionary trends by means of exercise and competition performance measures suggests of a heightened importance of neuromuscular factors. In conclusion, during the preseason players "recover" body composition profile and neuromuscular and endurance competitive capacity. Within in-season, and more robustly towards ECP, alterations in neuromuscular performance seem to be force-velocity dependent, and in some cases, physiological determinants and endurance performance may be compromised when considering other in-season moments. Importantly, there is a substantial variability in team responses that can be observed during in-season. Consequently, this informs on the need to both provide a regular training stimulus and adequate monitorization throughout the season.

A repeated shuttle sprint test with female and male international field hockey players is reliable and associated with single sprint but not intermittent endurance performance

Field hockey is a high-intensity intermittent team sport that has recently undergone a series of rule changes that have resulted in a greater demand for repeated high-intensity movements. Coaches and practitioners now require a reliable assessment of repeated accelerations, decelerations and changes of direction to assess these important match qualities. This investigation assessed the test-retest reliability of a novel 6x40m repeated shuttle sprint test (20m + 20m with a 180° turn) and its association with 40m straight line sprint and YoYo Intermittent Recovery Test performance in 28 International field hockey players (n = 14 females and n = 14 males). The sum of 6 sprint times (SUM) demonstrated ‘excellent’ (ICC = 0.94 and CV = 0.59%) and ‘good’ (ICC = 0.84 and CV = 0.75%) reliability in females and males, respectively. Best sprint time during the repeated shuttle sprint test also demonstrated suitable reliability to evaluate field hockey physical performance (ICC = 0.92 & 0.76, CV = 0.76% & 1.00% in females and males, respectively). SUM was significantly associated with 40 m straight line sprint performance in females (r = 0.90; p<0.001) and males (r = 0.92; p<0.001), but only a weak association was found with YoYo Intermittent Recovery Test performance for either group (r = 0.20; p = 0.495 & r = -0.19; p = 0.525 in females and males, respectively). In summary, field hockey testing batteries that include a repeated shuttle sprint test should consider including a test of intermittent endurance. Further, changes in SUM greater than 1.0% can be confidently interpreted by coaches and practitioners as a real change for both female and male elite field hockey players.

Comparison of VO2peak from the Progressive Aerobic Cardiovascular Endurance Run (PACER) and treadmill in children

Background/Objectives

Methods

Results

Conclusions

Effects of congested match periods on acceleration and deceleration profiles in professional soccer

The aim of the present study was to analyse the influence of congested periods of matches on the acceleration (Acc) and deceleration (Dec) profiles of elite soccer players. Twenty-three elite male professional soccer players participated in the study across 31 official matches. Assessed periods included: (i) congested periods (three to four days between games), and (ii) non-congested periods (more than four days between games). Physical activity during matches was recorded during games using a 10Hz global positioning system device, coupled with a 100 Hz accelerometer, and was analysed according to the periods. Maximal Acc- (73.2 ± 20.3 vs. 84.918.5 m), high Acc- (244.0 ± 49.5 vs. 267.0 ± 37.8 m), maximal Dec- (139.0 ± 44.8 vs. 152.039.3 m) and the total decelerating- distance (5132 ± 690 vs. 5245 ± 552 m) were lower in congested than in non-congested periods (p < 0.05, effect size 0.31–0.70). Neither a main effect of playing position nor a period*playing position interaction on Acc and Dec were observed (p > 0.05). It was concluded that Acc and Dec match activities were significantly affected during congested periods compared to non-congested highlighting a possible fatigue accumulation being responsible for the observed decrement in physical activity. Monitoring Acc and Dec metrics throughout particular periods of congested fixtures amongst professional soccer teams is advised and may be a way to assess physical and fatigue status.

Effect of repeated sprint training on isokinetic strength parameters in youth soccer players

BACKGROUND: Sprint drills are part of the soccer training routine for their resemblance to match activities. There is a lack of information in the literature about the changes in isokinetic skeletal muscle strength in response to sprint training. OBJECTIVE: This study evaluates the effects of eight weeks, on-season repeated sprint training with a change of direction on isokinetic strength parameters in well-trained youth soccer players. METHODS: Nineteen well-trained youth soccer players volunteered to participate in the study. The training program included three sets of six, 40 m (20 + 20 m) shuttle sprints twice a week for eight weeks. Isokinetic peak moment, work, and power of knee extensors and flexors were measured at angular velocities of 60, 180 and 240∘/s. Pre- and post-training valid isokinetic sector data were compared. RESULTS: Following the training period, dominant and non-dominant legs’ peak moment, work, and power values for both extensor and flexor muscle groups improved significantly at various angular velocities. CONCLUSIONS: Isokinetic strength enhancement may be explained with the induction of muscle hypertrophy following a prolonged period of sprint training.

Exploring the Determinants of Repeated-Sprint Ability in Adult Women Soccer Players

This study aimed to explore the main determinants of repeated-sprint ability (RSA) in women soccer players considering aerobic capacity, sprinting performance, change-of-direction, vertical height jump, and hip adductor/abductor isometric strength. Twenty-two women soccer players from the same team participating in the first Portuguese league were observed. Fitness assessments were performed three times during a 22-week cohort period. The following assessments were made: (i) hip abductor and adductor strength, (ii) squat and countermovement jump (height), (iii) change-of-direction test, (iv) linear sprinting at 10- and 30-m, (v) RSA test, and (vi) Yo-Yo intermittent recovery test level 1. Positive moderate correlations were found between peak minimum RSA and adductor and abductor strength (r = 0.51, p < 0.02 and r = 0.54, p < 0.01, respectively). Positive moderate correlations were also found between peak maximum RSA and adductor and abductor strength (r = 0.55, p < 0.02 and r = 0.46, p < 0.01, respectively). Lastly, a moderate negative correlation was found between fatigue index in RSA and YYIR1 test performance (r = -0.62, p < 0.004). In conclusion, abductor and adductor isometric strength-based coadjutant training programs, together with a high degree of aerobic endurance, may be suitable for inducing RSA in female soccer players.

Metabolic and Cardiorespiratory Responses of Semiprofessional Football Players in Repeated Ajax Shuttle Tests and Curved Sprint Tests, and Their Relationship with Football Match Play

In this study, the Ajax Shuttle Test (AST) and the Curved Sprint Test (CST) were conducted on semiprofessional football players to evaluate (1) their test performance, (2) the extent of anaerobic glycolysis by measuring blood lactate, (3) performance decrement and onset of fatigue, and (4) the correlation between selected physiological variables and test performance. Thirty-two semiprofessional Polish football players participated in this study. Both AST and CST were conducted on an outdoor football ground and were conducted in two sets; each set had six repetitions. In the case of AST, the total duration for 6 repetitions of the exercise in Sets 1 and 2 were 90.63 ± 3.71 and 91.65 ± 4.24 s, respectively, whereas, in the case of CST, the respective values were 46.8 ± 0.56 and 47.2 ± 0.66 s. Peak blood lactate concentration [La] after Sets 1 and 2 of AST were 14.47 ± 3.77 and 15.00 ± 1.85 mmol/L, and in the case of CST, the values were 8.17 ± 1.32 and 9.78 ± 1.35 mmol/L, respectively. Performance decrement in AST was more than in CST, both after Set 1 (4.32 ± 1.43 and 3.31 ± 0.96 in AST and CST, respectively) and Set 2 (7.95 ± 3.24 and 3.71 ± 1.02 in AST and CST, respectively). Only in a few of the repetitions, pulmonary ventilation (V_E) and oxygen uptake (VO₂) were found to be significantly correlated with the performance of the volunteers in both AST and CST. Respiratory exchange ratio (RER) was significantly correlated with most of the repetitions of AST, but not with CST. The study concludes that (1) AST shows more dependence on the anaerobic glycolytic system than shorter repetitive sprints (as in CST), (2) there is more performance decrement and fatigue in AST than in CST, and (3) early decrease in performance and fatigue in the semiprofessional football players in AST and CST may be due to the insufficiency of their aerobic energy system.

The Use of Acute Exercise Interventions as Game Day Priming Strategies to Improve Physical Performance and Athlete Readiness in Team-Sport Athletes: A Systematic Review

BACKGROUND

The use of exercise as a priming strategy to enhance sport performance is becoming increasingly popular in professional sports and as an area of research interest. Early research suggests that the acute physiological responses to exercise can positively influence performance for up to 48 h. There is yet to be a comprehensive review of exercise strategies which could be implemented specifically on the day of competition.

OBJECTIVES

The aim of this systematic review was to provide a synthesis of research investigating acute exercise interventions as game day priming strategies for team-sport athletes to improve physical performance and athlete readiness when implemented in the 1-12 h prior to competition.

METHODS

A literature search of SPORTDiscus, PubMed and Cochrane Central Register for Controlled Trials was conducted. A total of 6428 studies were retrieved and assessed against the following inclusion criteria: (1) randomised controlled trials and non-randomised comparative studies with reported pre-post intervention outcomes; (2) exercise interventions were applied 1-12 h prior to the assessment of outcome measures. Studies were excluded if they used nutrition, supplementation, pre-heating, pre-cooling, stretching, massage or vibration training as the priming strategies, or if interventions were performed at altitude or in hypoxic environments. Studies were assessed for methodological quality at the study level using the Physiotherapy Evidence Database (PEDro) scale.

RESULTS

Twenty-nine studies satisfied the eligibility criteria and were included in this review. Studies were categorised as resistance training; cycling; running; and other strategies. Resistance training using heavy loads at low volumes increased strength and power measures following a 4-6 h recovery, with limited improvements observed following shorter (1-3 h) and longer (6-12 h) recovery periods. Running-based sprint priming led to improvements in subsequent sprint and repeat sprint performance following a 5-6 h recovery, whereas cycling improved counter-movement jump height in a single study only. No significant differences were reported in any performance measures following endurance-based running or cycling strategies. Physiological markers, such a hormone and blood lactate responses, showed mixed results between studies.

CONCLUSIONS

High-intensity low-volume resistance training leads to a greater physiological and performance response than high-volume resistance training. Maximal running sprints may be more effective than maximal cycling sprints due to an increased physiological demand; however, loading protocols must also be considered in conjunction with exercise volume and movement specificity to achieve a beneficial response for subsequent performance. There is limited evidence to suggest endurance cycling or running exercise is beneficial as a priming strategy.

Cardiac Parasympathetic Reactivation Following Small-Sided Games, Repeated Sprints and Circuit Training in Elite Handball Players

To compare acute parasympathetic reactivation following usual training exercises, the acute post-exercise heart rate (HR) and heart rate variability (HRV) were analysed. Fourteen elite male handball players completed three separate sessions of 16-min small-sided games (SSGs), repeated sprints (RSs) consisting of two sets of six repetitions of a 25-m sprint with a 180° change of direction (12.5 m + 12.5 m) every 25 s and 40 min of handball-specific circuit training (CT, one brief action every 40 s). The HR was recorded during the exercises; HRV was assessed 10 min before and after exercise. The exercise HR was higher for SSGs than RSs and it was higher for RSs than CT. Comparison of the baseline and acute post-exercise HRV values showed that parasympathetic indices decreased following SSG (p < 0.01 – p < 0.0001; large effect size) and RS (p < 0.05 –p < 0.01; large effect size) interventions. For CT, recovery values remained similar to the baseline (small effect size). The comparison of the acute recovery period between exercise modalities showed that the root mean square of the successive differences (RMSSD) was lower for SSGs than RSs and CT. No difference in any HRV indices was observed between RSs and CT. Time-varying of RMSSD for successive 30 s segments during the 10 min recovery period showed lower values for SSGs than CT for all tested points; the progressive increase in the beat-to-beat interval was similar for all interventions. In conclusion, SSGs caused the greatest post-exercise vagal disruption and it is likely that CT is the exercise modality that least delays over-all recovery. These results might help coaches design better training sessions by understanding athletes’ recovery status after completing their conditioning exercises.

New Insights into Mechanical, Metabolic and Muscle Oxygenation Signals During and After High-Intensity Tethered Running

High-intensity exercises including tethered efforts are commonly used in training programs for athletes, active and even sedentary individuals. Despite this, the knowledge about the external and internal load during and after this effort is scarce. Our study aimed to characterize the kinetics of mechanical and physiological responses in all-out 30 seconds (AO30) tethered running and up to 18 minutes of passive recovery. Additionally, in an innovative way, we investigated the muscle oxygenation in more or less active muscles (vastus lateralis and biceps brachii, respectively) during and after high-intensity tethered running by near-infrared spectroscopy – NIRS. Twelve physically active young men were submitted to AO30 on a non-motorized treadmill to determine the running force, velocity and power. We used wearable technologies to monitor the muscle oxygenation and heart rate responses during rest, exercise and passive recovery. Blood lactate concentration and arterial oxygen saturation were also measured. In a synchronized analysis by high capture frequency of mechanical and physiological signals, we advance the understanding of AO30 tethered running. Muscle oxygenation responses showed rapid adjustments (both, during and after AO30) in a tissue-dependence manner, with very low tissue saturation index observed in biceps brachii during exercise when compared to vastus lateralis. Significant correlations between peak and mean blood lactate with biceps brachii oxygenation indicate an important participation of less active muscle during and after high-intensity AO30 tethered running.

The 30-15 Intermittent Fitness Test: A Reliable, Valid, and Useful Tool to Assess Aerobic Capacity in Female Basketball Players

Purpose: The purpose of this study was to determine the reliability, validity, and usefulness of 30-15 Intermittent Fitness Test (30-15_IFT) in female basketball players. Methods: Nineteen female basketball players (17.82 ± 1.94 yr, 175.4 ± 7.3 cm, 67.9 ± 7.7 kg) competing in the National Croatian League performed one trial of a continuous treadmill running test and two trials of the 30-15_IFT. The 30-15_IFT involves 30-s runs across a 40-m course interspersed with 15 s of walking, with running speed increasing every 45 s. The continuous treadmill running test was used as the criterion for validation. Results: High to very high reliability across test-retest trials were observed for maximal oxygen uptake (VO₂max) (CV = 4.9%, ICC = 0.85), the 30-15_IFT end-running velocity (V_IFT) (CV = 6.0%, ICC = 0.85), and maximal heart rate (HRmax) (CV = 4.8%, ICC = 0.96). Criterion validity was supported for the 30-15_IFT with strong to very strong relationships with VO₂max (r =0.69), V_IFT (r =0.74), and HRmax (r =0.73) attained during the continuous treadmill running test. The typical error (TE) of the 30-15_IFT was greater than the smallest worthwhile change for VO₂max (1.16 > 0.42 ml/kg/min), V_IFT (0.56 > 0.20 km/h), and HRmax (2.15 > 1.89 bpm) adjudging usefulness of the test as marginal. The TE of 0.56 km/h (90% CI = 0.44-0.77 km/h) demonstrates changes in the performance of one to two stages (0.5-1.0 km/h) are meaningful. Conclusions: The 30-15_IFT possesses acceptable reliability and validity to assess maximal aerobic fitness capacity in female basketball players. While the usefulness of the 30-15_IFT was marginal, meaningful changes in performance consisted of only one to two stages. The present findings support the 30-15_IFT as a practical testing option for basketball practitioners to assess fitness capacities in female players.

Effects of Linear Versus Changes of Direction Repeated Sprints on Intermittent High Intensity Running Performance in High-level Junior Football Players over an Entire Season: A Randomized Trial

Background: Changes of direction (COD) repeated sprints (RSs) might have greater relevance to football than linear RSs. We aimed to compare the effects of linear and COD RSs on intermittent high intensity running (HIR) over an entire season. Methods: In total, 19 high-level male football players (16–19 years) randomly performed linear RSs or COD RSs twice a week during their competitive season over 22 weeks. Yo-Yo intermittent recovery test level 2 (Yo-Yo IR2), and 10- and 20-m sprint was assessed pre-, mid- (11 weeks), and post-intervention (22 weeks). Maximal oxygen uptake (VO_2max) was assessed pre- and post-intervention. Results: There was no interaction effect (time x group) in Yo-Yo IR2 (p = 0.36, _pη² = 0.06) or sprint tests (10 m: p = 0.55, _pη² = 0.04, 20 m: p = 0.28 _pη² = 0.08), and no change differences between groups. There was a main effect of time for Yo-Yo IR2 (p = 0.002, _pη² = 0.31) but not in sprints or VO_2max. Conclusion: Linear and COD RS exercise twice a week over 22 weeks equally improves intermittent HIR performance but does not improve sprint time or aerobic power in high-level junior football players. However, due to our two-armed intervention, we cannot exclude possible effects from other exercise components in the players’ exercise program.

Effects of different repeated sprint-training frequencies in youth soccer players

The aim of this study was to determine the effects of 2 different repeated-sprint ability (RSA) training frequencies (2 RSA sessions per week [RSA2D] or 1 RSA session [RSA1D]) under volume-equated conditions on sprint and RSA performance in under-15 (U15) soccer players. Twenty-seven youth male soccer players (age: 12.29±0.47 years; height: 158.35±10.86 cm; weight: 45.08±8.05 kg) were randomly assigned to RSA2D (n=14) or RSA1D (n=13) groups. The players performed the same RSA training for 6 weeks, and only the training frequency differed between the groups. Before and after the training period, 5 m sprint, 10 m sprint, 20 m sprint and the RSA test were assessed. No significant time × group interactions were observed (p>0.05). Within-group analysis showed significant improvements in 20 m sprint (p=0.046, partial eta squared [η _p ² ] = 0.150, large) and RSA average time (p=0.001, η _p ² =0.438, large), fastest time (p=0.012, η _p ² =0.229, large), and total time (p=0.001, η _p ² =0.438, large) from pre-test to post-test in RSA1D and RSA2D groups. However, no significant pre-post changes (p>0.05) were found in 5 m and 10 m sprint tests. In the between-group analysis, there were no significant differences between RSA1D and RSA2D groups in any variable. In conclusion, the current findings suggest that 6 weeks of RSA training 1 or 2 times per week in addition to typical soccer training produced significant and similar improvements in sprint and RSA performances. This information could be useful for coaches when planning training sessions during congested fixtures of soccer competitions or in periods when the emphasis should be placed on other physical qualities.

Comparative Effects of Two Interval Shuttle-Run Training Modes on Physiological and Performance Adaptations in Female Professional Futsal Players

Teixeira, AS, Arins, FB, De Lucas, RD, Carminatti, LJ, Dittrich, N, Nakamura, FY, and Guglielmo, LGA. Comparative effects of two interval shuttle-run training modes on physiological and performance adaptations in female professional futsal players. J Strength Cond Res 33(5): 1416-1428, 2019-The purpose of this study was to analyze the effects of 2 shuttle-run interval training (SRIT) models with 1 and 3 directional changes per running bout on the aerobic and anaerobic performances of elite female futsal players. Sixteen players competing in the Brazilian National Division League took part in the study. The training protocols consisted of shuttle-run intervals organized in 4 sets of 4-minute bouts with 3 minutes of rest intervals between the sets. The SRIT models were composed of 1 (7.5 seconds running and 7.5 seconds pause [SRIT7.5×7.5]; n = 7) or 3 (15 seconds running and 15 seconds pause [SRIT15×15]; n = 9) directional changes. The athletes performed the following tests before and after a 5-week training period: incremental treadmill test (ITT), futsal intermittent endurance test (FIET) (with respective peak speeds [PSs]), and a repeated sprint ability (RSA) test. After the training period, PSFIET and speed at the second lactate turnpoint were very likely and almost certainly increased in both training regimens, respectively. SRIT15×15 induced possibly greater improvements in PSITT (+3.28%, 90% CL -0.16 to 6.82) and RSAmean (+1.17%, 90% CL -0.68 to 3.05) than SRIT7.5×7.5. In addition, SRIT15×15 resulted in a likely greater improvement in running economy (+4.33%, 90% CL -0.35 to 9.23) compared with SRIT7.5×7.5. In elite female futsal players, SRIT15×15 is a promising strategy to enhance performance-related physical fitness attributes in a short-term period (5 weeks) during the preseason, Because of its superior effects on these important aerobic and anaerobic qualities than a protocol with fewer directional changes.

Critical Speed as a Measure of Aerobic Fitness for Male Rugby Union Players

PURPOSE

To compare critical speed (CS) derived from all-out testing (AOT) for linear and shuttle running with metrics from a graded exercise test, the Yo-Yo Intermittent Recovery Test  Level 1 (YYIR1), and estimation of an 800-m-shuttle time trial.

METHODS

Twelve male rugby players completed a graded exercise test, the YYIR1, a linear AOT, shuttle AOTs of 25 and 50 m, and an 800-m-shuttle time trial consisting of 32 × 25-m shuttles.

RESULTS

Strong linear correlations were observed between maximum oxygen uptake ( V˙O2max ) and CS (m·s^-1) derived from the linear AOT (3.68 [0.62], r = .90, P < .01) and 50-m-shuttle AOT (3.19 [0.26], r = .83, P < .01). Conversely, V˙O2max showed lower correlations with speeds evoking CS from 25-m AOT (2.86 [0.18], r = .42, P = .18) and YYIR1 (4.36 [0.11], r = .55, P = .07). The 800-m time trial (213.58 [15.84] s) was best predicted using parameters from the 25-m AOT (r = .93, SEE = 6.60 s, P < .001).

CONCLUSIONS

The AOT is a valuable method of assessing performance-specific fitness, with CS from linear and 50-m-shuttle AOTs being strong predictors of V˙O2max , rivaling metrics from the graded exercise test. The YYIR1 offered limited utility compared with the AOT method.

Bi-exponential modeling derives novel parameters for the critical speed concept

All-out exercise testing (AOT) has emerged as a method for quantifying critical speed (CS) and the curvature constant (D'). The AOT method was recently validated for shuttle running yet how that method compares with linear running is unknown. In the present study, we utilized a novel bi-exponential model that derives CS and D' with additional new parameters from the AOT method. Fourteen male athletes (age = 21.6 ± 2.2 years; height = 177 ± 70 cm; weight = 83.0 ± 11.8 kg) completed a graded exercise test (GXT) to derive maximum oxygen uptake ( V ˙ O 2 max ) and the average speed between gas exchange threshold and V ˙ O 2 max (sΔ50%), a linear AOT, and two shuttle AOTs. Measurement agreement was determined using intraclass correlation coefficient (ICC α ), typical error (TE), and coefficient of variation (CV). The y-asymptote ( S 0 ) of the speed-time curve (3.52 ± 0.66 m·sec-1 ) did not differ from sΔ50% (3.49 ± 0.41 m·sec-1 ) or CS (3.77 ± 0.56 m·sec-1 ) (P = 0.34). Strong agreement was observed for estimates of CS (ICC α  = 0.92, TE = 0.18 m·sec-1 , and CV = 5.7%) and D' (ICC α  = 0.94, TE = 16.0 m, CV = 7.6%) with significant (P < 0.01) correlations observed between V ˙ O 2 max and CS and between S 0 and V ˙ O 2 max (r values of 0.74 and 0.84, respectively). The time constant of the decay in speed ( τ d ) and the amplitude between maximal speed and S 0 ( A d ) emerged as unique metrics. The A d and τ d metrics may glean new insights for prescribing and interpreting high-intensity exercise using the AOT method.

Eight-Week Battle Rope Training Improves Multiple Physical Fitness Dimensions and Shooting Accuracy in Collegiate Basketball Players

Chen, WH, Wu, HJ, Lo, SL, Chen, H, Yang, WW, Huang, CF, and Liu, C. Eight-week battle rope training improves multiple physical fitness dimensions and shooting accuracy in collegiate basketball players. J Strength Cond Res 32(10): 2715-2724, 2018-Basketball players must possess optimally developed physical fitness in multiple dimensions and shooting accuracy. This study investigated whether battle rope (BR) training enhances multiple physical fitness dimensions, including aerobic capacity (AC), upper-body anaerobic power (AnP), upper-body and lower-body power, agility, and core muscle endurance, and shooting accuracy in basketball players and compared its effects with those of regular training (shuttle run [SR]). Thirty male collegiate basketball players were randomly assigned to the BR or SR groups (n = 15 per group). Both groups received 8-week interval training for 3 sessions per week; the protocol consisted of the same number of sets, exercise time, and rest interval time. The BR group exhibited significant improvements in AC (Progressive Aerobic Cardiovascular Endurance Run laps: 17.6%), upper-body AnP (mean power: 7.3%), upper-body power (basketball chest pass speed: 4.8%), lower-body power (jump height: 2.6%), core muscle endurance (flexion: 37.0%, extension: 22.8%, and right side bridge: 23.0%), and shooting accuracy (free throw: 14.0% and dynamic shooting: 36.2%). However, the SR group exhibited improvements in only AC (12.0%) and upper-body power (3.8%) (p < 0.05). The BR group demonstrated larger pre-post improvements in upper-body AnP (fatigue index) and dynamic shooting accuracy than the SR group did (p < 0.05). The BR group showed higher post-training performance in upper-body AnP (mean power and fatigue index) than the SR group did (p < 0.05). Thus, BR training effectively improves multiple physical fitness dimensions and shooting accuracy in collegiate basketball players.

Energetics of male field-sport athletes during the 3-min all-out test for linear and shuttle-based running

PURPOSE

All-out, non-steady state running makes for difficult comparisons regarding linear and shuttle running; yet such differences remain an important distinction for field-based sports. The purpose of the study was to determine whether an energetic approach could be used to differentiate all-out linear from shuttle running.

METHODS

Fifteen male field-sport athletes volunteered for the study (means ± SD): age, 21.53 ± 2.23 years; height, 1.78 ± 0.68 m; weight, 83.85 ± 11.73 kg. Athletes completed a graded exercise test, a 3-min linear all-out test and two all-out shuttle tests of varied distances (25 m and 50 m shuttles).

RESULTS

Significant differences between the all-out tests were found for critical speed (CS) [F(8.97), p < 0.001), D' (finite capacity for running speeds exceeding critical speed) [F(7.83), p = 0.001], total distance covered [F(85.31), p < 0.001], peak energetic cost ([Formula: see text]) [F(45.60), p < 0.001], peak metabolic power ([Formula: see text]) [F(23.36), p < 0.001], average [Formula: see text] [F(548.74), p < 0.001], maximal speed [F(22.87), p < 0.001] and fatigue index [F(3.93), p = 0.027]. Non-significant differences were evident for average [Formula: see text] [F(2.47), p = 0.097], total [Formula: see text] [F(0.86), p = 0.416] and total [Formula: see text] [F(2.11), p = 0.134].

CONCLUSIONS

The energetic approach provides insights into performance characteristics that differentiate linear from shuttle running, yet surprising similarities between tests were evident. Key parameters from all-out linear and shuttle running appear to be partly interchangeable between tests, indicating that the final choice between linear and shuttle testing should be based on the requirements of the sport.

Muscle Oximetry in Sports Science: A Systematic Review

BACKGROUND

Since the introduction (in 2006) of commercially available portable wireless muscle oximeters, the use of muscle near-infrared spectroscopy (NIRS) technology is gaining in popularity as an application to observe changes in muscle metabolism and muscle oxygenation during and after exercise or training interventions in both laboratory and applied sports settings.

OBJECTIVES

The objectives of this systematic review were to highlight the application of muscle oximetry in evaluating oxidative skeletal muscle performance to sport activities and emphasize how this technology has been applied to exercise and training.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in a systematic fashion to search, assess and synthesize existing literature on this topic. The Scopus and MEDLINE/PubMed electronic databases were searched to 1 March 2017. Potential inclusions were screened against eligibility criteria relating to recreationally trained to elite athletes, with or without training programs, who must have assessed physiological variables monitored by commercial oximeters or NIRS instrumentation.

RESULTS

Of the 14,609 identified records, only 57 studies met the eligibility criteria. This systematic review highlighted a number of key findings in 16 sporting activities. Overall, NIRS information can be used as a marker of skeletal muscle oxidative capacity and for analyzing muscle performance factors.

CONCLUSIONS

Although NIRS instrumentation is promising in evaluating oxidative skeletal muscle performance when used in sport settings, there is still the need for further instrumental development and randomized/longitudinal trials to support the detailed advantages of muscle oximetry utilization in sports science.

A systematic review examining the physiological, perceptual, and performance effects of active and passive recovery modes applied between repeated-sprints

INTRODUCTION

Repeated-sprinting involves performing frequent short sprints (≤10 s) interspersed with brief recovery periods (≤60 s). Studies involving repeated-sprint protocols have typically employed active or passive recovery modes applied between running and cycling sprints. This review synthesized the literature to determine the acute physiological, perceptual, and performance effects of recovery mode applied between repeated-sprints during running and cycling protocols.

EVIDENCE ACQUISITION

A systematic search was conducted according to PRISMA guidelines. Articles were retrieved from PubMed, Scopus, SPORTDiscus, and MEDLINE databases. Studies were eligible if they: 1) compared active and passive recovery applied between repeated-sprints; 2) examined sprints lasting ≤10 s, and; 3) included ≤60 s recovery between sprints. Nine studies were included in this review. Five of the included studies examined running and four studies examined cycling.

EVIDENCE SYNTHESIS

Passive recovery induced less physiological stress (heart rate, oxygen consumption, and changes in oxyhemoglobin), lower perceptual stress (rating of perceived exertion), and reduced performance decrement (sprint time, speed, and sprint decrement) compared to active recovery in all running studies. Findings were equivocal in cycling.

CONCLUSIONS

Application of passive recovery between running repeated-sprints is recommended to reduce performance decrement than passive recovery. Alternatively, active recovery applied between running repeated-sprints provides greater physiological stress than passive recovery and may be a useful training overload strategy to promote physiological adaptation. The mixed findings for physiological and performance measures in cycling studies suggest further research is required to reach definitive conclusions regarding application of recovery modes between cycling repeated-sprints.

PlayerLoad Variables: Sensitive to Changes in Direction and Not Related to Collision Workloads in Rugby League Match Play

PURPOSE

To determine (1) how change-of-direction (COD) workloads influence PlayerLoad (PL) variables when controlling total distance covered and (2) relationships among collision workloads and PL variables during rugby league match play.

METHODS

Participants completed 3 protocols (crossover design) consisting of 10 repetitions of a 60-m effort in 15 s. The difference between protocols was the COD demands required to complete 1 repetition: no COD (straight line), 1° × 180° COD, or 3° × 180° COD. During rugby league matches, relationships among collision workloads, triaxial vector-magnitude PlayerLoad (PL_VM), anteroposterior + mediolateral PL (PL_2D), and PL_VM accumulated at locomotor velocities below 2 m·s^-1 (ie, PL_SLOW) were examined using Pearson correlations (r) with coefficients of determination (R²).

RESULTS

Comparing 3° × 180° COD to straight-line drills, PL_VM·min^-1 (d = 1.50 ± 0.49, large, likelihood = 100%, almost certainly), PL_2D·min^-1 (d = 1.38 ± 0.53, large, likelihood = 100%, almost certainly), and PL_SLOW·min^-1 (d = 1.69 ± 0.40, large, likelihood = 100%, almost certainly) were greater. Collisions per minute demonstrated a distinct (ie, R² < .50) relationship from PL_VM·min^-1 (R² = .30, r = .55) and PL_2D·min^-1 (R² = .37, r = .61). Total distance per minute demonstrated a very large relationship with PL_VM·min^-1 (R² = .62, r = .79) and PL_2D·min^-1 (R² = .57, r = .76).

CONCLUSIONS

PL variables demonstrate (1) large increases as COD demands intensify, (2) separate relationships from collision workloads, and (3) moderate to very large relationships with total distance during match play. PL variables should be used with caution to measure collision workloads in team sport.

Energy expenditure associated with walking speed and angle of turn in children

Purpose

Recent studies have suggested that turning is power intensive. Given the sporadic and irregular movement patterns of children, such findings have important implications for the assessment of true energy expenditure associated with habitual physical activity. The purpose of this study was to investigate the influence of walking speed and angle, and their interaction, on the energy expenditure of healthy children.

Methods

20 children (10.1 ± 0.5 years; 10 boys) participated in the study. On two separate days, participants completed a turning protocol involving 3-min bouts of walking at one of the 16 speed (2.5, 3.5, 4.5, and 5.5 km h^− 1) and angle (0°, 45°, 90°, and 180°) combinations, interspersed by 3 min seated rest. The movement involved 5 m straight walking interspaced with prescribed turns with speed dictated by a digital, auditory metronome. Breath-by-breath gas exchange was measured, in addition to tri-axial acceleration and magnetic field intensity recorded at 100 Hz.

Results

Mixed models revealed a significant main effect for speed (p < 0.006) and angle (p < 0.006), with no significant interaction between speed and angle (p > 0.006). Significant differences to straight-line walking energy expenditure within speed were established for 3.5 and 5.5 km h^− 1 for 180° turns (~ 13% and ~ 30% increase, respectively).

Conclusion

These findings highlight the importance of accounting for the magnitude and frequency of turns completed when estimating children’s habitual physical activity and have significant implications for the assessment of daily energy expenditure.

Reduced Fatigue in Passive Versus Active Recovery: An Examination of Repeated-Change-of-Direction Sprints in Basketball Players

PURPOSE

To investigate the physiological and performance effects of active and passive recovery between repeated-change-of-direction sprints.

METHODS

Eight semiprofessional basketball players (age: 19.9 [1.5] y; stature: 183.0 [9.6] cm; body mass: 77.7 [16.9] kg; body fat: 11.8% [6.3%]; and peak oxygen consumption: 46.1 [7.6] mL·kg^-1·min^-1) completed 12 × 20-m repeated-change-of-direction sprints (Agility 5-0-5 tests) interspersed with 20 seconds of active (50% maximal aerobic speed) or passive recovery in a randomized crossover design. Physiological and perceptual measures included heart rate, oxygen consumption, blood lactate concentration, and rating of perceived exertion. Change-of-direction speed was measured during each sprint using the change-of-direction deficit (CODD), with summed CODD time and CODD decrement calculated as performance measures.

RESULTS

Average heart rate (7.3 [6.4] beats·min^-1; P = .010; effect size (ES) = 1.09; very likely) and oxygen consumption (4.4 [5.0] mL·kg^-1·min^-1; P = .12; ES = 0.77; unclear) were moderately greater with active recovery compared with passive recovery across sprints. Summed CODD time (0.87 [1.01] s; P = .07; ES = 0.76, moderate; likely) and CODD decrement (8.1% [3.7%]; P < .01; ES = 1.94, large; almost certainly) were higher with active compared with passive recovery. Trivial-small differences were evident for rating of perceived exertion (P = .516; ES = 0.19; unclear) and posttest blood lactate concentration (P = .29; ES = 0.40; unclear) between recovery modes.

CONCLUSIONS

Passive recovery between repeated-change-of-direction sprints may reduce the physiological stress and fatigue encountered compared with active recovery in basketball players.

Oxygen uptake kinetics and speed-time correlates of modified 3-minute all-out shuttle running in soccer players

How parameters derived from oxygen uptake V˙O2 kinetics relate to critical speed is not fully understood, and how such parameters relate to more sport-specific performances, such as shuttle running, has not been investigated. Therefore, the primary aims of the present student were to examine the V˙O2 kinetics during all-out linear and shuttle running and compare physiological variables of all-out running to variables measured during a graded exercise test (GXT). Fifteen male soccer players performed a graded exercise test (GXT) and the V˙O2 kinetics from a series of three different 3-min all-out tests (3MT’s) were evaluated. V˙O2max achieved during the GXT did not differ from maximal V˙O2 achieved during the all-out tests (F = 1.85, p = 0.13) (overall ICC = 0.65; typical error = 2.48 ml∙kg^-1∙min^-1; coefficient of variation = 4.8%). A moderate, inverse correlation (r = -0.62, p = 0.02) was observed between τ (14.7 ± 1.92 s) and CS (3.96 ± 0.52 m∙s^-1) despite the narrow SD for τ. No differences (p > 0.05) were observed for any of the V˙O2 kinetics between continuous and shuttle running bouts. The linear running 3MT (r3MT) represents a viable surrogate to the GXT and data beyond CS and D’ may be gleaned by using the bi-exponential speed-time model.

Heart rate and pulmonary oxygen uptake response in professional badminton players: comparison between on-court game simulation and laboratory exercise testing

PURPOSE

Badminton is characterized by bouts of high intensity interspersed by short recovery periods. Aerobic assessment via indirect calorimetry is impractical on court because of the encumbrance of portable metabolic devices. When the relationship between heart rate (HR) and pulmonary oxygen uptake [Formula: see text] [Formula: see text] is linear, HR monitoring can provide an indirect estimation of metabolic demands on court. However, owing to the intermittent nature of badminton, the [Formula: see text] relationship will differ from that obtained in the laboratory, making its use on court questionable. The aims of this study were to (i) assess cardiorespiratory and metabolic responses during on-court badminton rally simulations at different intensities and (ii) compare [Formula: see text] relationships obtained from laboratory and on-court measurements.

METHODS

The study sample was seven professional badminton players (age 16.9 ± 2.1 years; body mass 62.8 ± 9.2 kg; stature 1.71 ± 0.09 m). [Formula: see text] HR, and other respiratory and metabolic parameters were assessed in the laboratory with an incremental intermittent Astrand-type test (IIAT) and on court during rally simulations at three different intensities.

RESULTS

Cardiorespiratory parameters measured during the rallies reached 95% of maximal IIAT values. The [Formula: see text] slope and intercept differed in the on-court and the IIAT conditions (P = 0.012 and P = 0.008, respectively).

CONCLUSIONS

The difference in [Formula: see text] regression lines between the IIAT and the on-court condition indicates that HR monitoring may not provide accurate data on the aerobic demands of specific on-court badminton tasks. HR monitoring should be preceded by an indirect calorimetry test on court to assess aerobic demands more precisely.

An examination of a modified Yo-Yo test to measure intermittent running performance in rugby players

This study examined how starting each shuttle in the prone position altered the internal, external and perceptual responses to the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1). Using a randomized crossover design, 17 male rugby players completed the Yo-Yo IR1 and prone Yo-Yo IR1 on two separate occasions. External loads (via microtechnology), [Formula: see text], heart rate (HR) and rating of perceived exertion (RPE) were measured at 160, 280 and 440 m (sub-maximal) and when the test was terminated (peak). The pre-to-post change in blood lactate concentration (Δ[La]_b) was determined for both tests. All data were analysed using effect sizes (ES) and magnitude-based inferences. Between-trial differences (ES ± 90% CL) indicated that total distance was most likely lower (-1.87 ± 0.19), whereas other measures of peak external load were likely to very likely higher during the prone Yo-Yo IR1 (0.62-1.80). Sub-maximal RPE was likely to most likely higher (0.40-0.96) and peak RPE very likely higher (0.63 ± 0.41) in the prone Yo-Yo IR1. The change in [La]_b was likely higher after the prone Yo-Yo IR1. Mean HR was possibly lower at 440 m (-0.25 ± 0.29) as was peak HR (-0.26 ± 0.25) in the prone Yo-Yo IR1. [Formula: see text], [Formula: see text] and [Formula: see text] were likely to very likely higher at 280 and 440 m (ES = 0.36-1.22), while peak values were possibly to likely higher (ES = 0.23-0.37) in the prone Yo-Yo IR1. Adopting a prone position during the Yo-Yo IR1 increases the internal, external and perceptual responses, placing greater emphasis on metabolically demanding actions typical of rugby.

Effects of local versus remote ischemic preconditioning on repeated sprint running performance

BACKGROUND

The aim of this study was to compare the effect of local and remote ischemic preconditioning (IPC) on repeated sprint exercise.

METHODS

Twelve males (age 22±2 years; stature 1.79±0.07 m; body mass 77.8±8.4 kg; mean±SD) completed four trials consisting of remote (arm) and local (leg) IPC and SHAM interventions prior to repeated sprint exercise (3x[6x15+15-m] shuttle sprints), in a double-blind, randomized, crossover designed study. These tests were immediately preceded by IPC (4x5-minute intervals at 220 mmHg bilateral occlusion) or SHAM treatment (4x5-minute intervals at 20 mmHg bilateral occlusion). Sprint performance and percentage decrement score alongside measurement of Tissue Saturation Index, blood lactate and RPE were measured throughout the intervention.

RESULTS

During the IPC/SHAM intervention there was a large decrease in TSI for IPC-arm in comparison to IPC-leg (P<0.05), however IPC-legs resulted in greater soreness compared with the other three conditions (P<0.05). There was no main effects or interaction effects for sprint performance. There was a significant effect of condition (P=0.047, r=0.56) on percentage decrement score across all 18 sprints with IPC demonstrating less fatigue than SHAM. There were no other effects of IPC during the sprint trials for any other physiological measure.

CONCLUSIONS

In conclusion local IPC resulted in more pain/soreness during the IPC/SHAM intervention but both remote and local IPC reduced the fatigue associated with repeated sprint exercise.

Directional Change Mediates the Physiological Response to High-Intensity Shuttle Running in Professional Soccer Players

The purpose of this study was to investigate the influence that different frequencies of deceleration and acceleration actions had on the physiological demands in professional soccer players. Thirteen players were monitored via microelectromechanical devices during shuttle running protocols which involved one, three, or seven 180 degree directional changes. Heart rate exertion (HRE) (1.1 ± 0.7) and rating of perceived exertion (RPE) (5 ± 1) were significantly higher for the protocol which included seven directional changes when compared to the protocols which included one (HRE 0.5 ± 0.3, ES = 1.1, RPE 3 ± 0, ES = 2.7) or three (HRE 0.5 ± 0.2, ES = 1.1, RPE 3 ± 1, ES = 1.9) directional changes (p < 0.05). The gravitational force (g-force) as measured through accelerometry (ACC) also showed a similar trend when comparing the seven (8628.2 ± 1630.4 g) to the one (5888.6 ± 1159.1 g, ES = 1.9) or three (6526.9 ± 1257.6 g, ES = 1.4) directional change protocols (p < 0.05). The results of this study suggest that increasing the frequency of decelerations and accelerations at a high intensity running (HIR) speed alters the movement demands and elevates the physiological responses in professional players. This data has implications for the monitoring of physical performance and implementation of training drills.

Accelerated point of muscle deoxygenation during the 20-m shuttle run test

This study examined whether the point of accelerated deoxygenation of active muscle occurs during the 20-m shuttle run test (20mSRT) and, if so, whether it is associated with exercise performance in the test. Twenty-nine male subjects performed the 20mSRT, and concentration changes in oxyhaemoglobin (ΔOxy-Hb) and deoxyhaemoglobin (ΔDeoxy-Hb) in the m. vastus lateralis were measured using a portable near-infrared spectroscopy device. The difference between the relative concentration changes in ΔOxy-Hb and ΔDeoxy-Hb (Δ[Oxy-Hb - Deoxy-Hb]) was regarded as the muscle oxygenation index. Group-averaged Δ[Oxy-Hb - Deoxy-Hb] showed progressive decrease during the test. However, among the individuals, we found an accelerated point of decrease in Δ[Oxy-Hb - Deoxy-Hb] in 20 subjects, which revealed that the laps at the accelerated point correlated with the total laps (r = 0·78). These results demonstrate that the accelerated deoxygenation of active muscle occurs during the 20mSRT, but not in all cases. Our findings also indicate that if the accelerated point of muscle deoxygenation occurs, the timing of its appearance is related to 20mSRT performance.

Wearable Lactate Threshold Predicting Device is Valid and Reliable in Runners

Borges, NR and Driller, MW. Wearable lactate threshold predicting device is valid and reliable in runners. J Strength Cond Res 30(8): 2212-2218, 2016-A commercially available device claiming to be the world's first wearable lactate threshold predicting device (WLT), using near-infrared LED technology, has entered the market. The aim of this study was to determine the levels of agreement between the WLT-derived lactate threshold workload and traditional methods of lactate threshold (LT) calculation and the interdevice and intradevice reliability of the WLT. Fourteen (7 male, 7 female; mean ± SD; age: 18-45 years, height: 169 ± 9 cm, mass: 67 ± 13 kg, V[Combining Dot Above]O2max: 53 ± 9 ml·kg·min) subjects ranging from recreationally active to highly trained athletes completed an incremental exercise test to exhaustion on a treadmill. Blood lactate samples were taken at the end of each 3-minute stage during the test to determine lactate threshold using 5 traditional methods from blood lactate analysis which were then compared against the WLT predicted value. In a subset of the population (n = 12), repeat trials were performed to determine both inter-reliability and intrareliability of the WLT device. Intraclass correlation coefficient (ICC) found high to very high agreement between the WLT and traditional methods (ICC > 0.80), with TEMs and mean differences ranging between 3.9-10.2% and 1.3-9.4%. Both interdevice and intradevice reliability resulted in highly reproducible and comparable results (CV < 1.2%, TEM <0.2 km·h, ICC > 0.97). This study suggests that the WLT is a practical, reliable, and noninvasive tool for use in predicting LT in runners.

The effects of skin and core tissue cooling on oxygenation of the vastus lateralis muscle during walking and running

Skin and core tissue cooling modulates skeletal muscle oxygenation at rest. Whether tissue cooling also influences the skeletal muscle deoxygenation response during exercise is unclear. We evaluated the effects of skin and core tissue cooling on skeletal muscle blood volume and deoxygenation during sustained walking and running. Eleven male participants walked or ran six times on a treadmill for 60 min in ambient temperatures of 22°C (Neutral), 0°C for skin cooling (Cold 1), and at 0°C following a core and skin cooling protocol (Cold 2). Difference between oxy/deoxygenated haemoglobin ([diffHb]: deoxygenation index) and total haemoglobin content ([tHb]: total blood volume) in the vastus lateralis (VL) muscle was measured continuously. During walking, lower [tHb] was observed at 1 min in Cold 1 and Cold 2 vs. Neutral (P˂0.05). Lower [diffHb] was seen at 1 and 10 min in Cold 2 vs. Neutral by 13.5 ± 1.2 µM and 15.3 ± 1.4 µM and Cold 1 by 10.4 ± 3.1 µM and 11.1 ± 4.1 µM, respectively (P˂0.05). During running, [tHb] was lower in Cold 2 vs. Neutral at 10 min only (P = 0.004). [diffHb] was lower at 1 min in Cold 2 by 11.3 ± 3.1 µM compared to Neutral and by 13.5 ± 2.8 µM compared to Cold 1 (P˂0.001). Core tissue cooling, prior to exercise, induced greater deoxygenation of the VL muscle during the early stages of exercise, irrespective of changes in blood volume. Skin cooling alone, however, did not influence deoxygenation of the VL during exercise.

Multi-Directional Sprinting and Acceleration Phase in Basketball and Handball Players Aged 14 and 15 Years

An important role in handball and basketball is played by ability to accelerate and ability to repeat multiple sprints. The aim of the study was to assess level of ability in multi-directional sprinting and running time over the first 5 m of the 30 m sprint in 93 basketball and handball players (46 boys and 47 girls) aged 14 to 15 years. The attempts were also made to find the relationships between the time of a 5-m run to evaluate initial acceleration phase and multi-directional sprinting evaluated using Five-Time Shuttle Run To Gates Test Statistical analysis revealed no important differences in times of 5-m runs and times of multi-directional sprinting between groups with different ages, genders, and sports specialties. Furthermore, no significant correlations were found based on Spearman's rank correlation coefficient between times of 5-m run and multi-directional sprinting in the most of subgroups studied.

Number of Directional Changes Alters the Physiological, Perceptual, and Neuromuscular Responses of Netball Players During Intermittent Shuttle Running

This study investigated whether an increased number of changes in direction altered the metabolic, cardiovascular, perceptual, and neuromuscular responses to intermittent shuttle running (ISR). Using a randomized crossover design, 10 female netball players completed 30 minutes of ISR over a 10-m (ISR10) and 20-m (ISR20) linear course. Measures of expired air, heart rate (HR), rating of perceived exertion, blood lactate concentration ([BLa]), and peak torque of knee extensors and flexors were measured. Differences (%change ± 90% CL) in VO2 (1.5 ± 5.6%) was unclear between conditions, whereas HR was possibly higher (1.5 ± 2.5%) and [BLa] very likely lower in ISR20 compared with ISR10 (-32.7 ± 9.9%). Rating of perceived exertion was likely lower in the ISR20 compared with the ISR10 condition at 15 (-5.0 ± 5.0%) and most likely lower at 30 minutes (-9.4 ± 2.0%). Sprint times over 20 m were likely slower during ISR20 at mid (3.9 ± 3.2%) but unclear after (2.1 ± 5.4%). Changes in muscle function were not different between ISR10 and ISR20 conditions for knee extension (-0.2 ± 0.9%) but were likely different for knee flexion (-5.7 ± 4.9%). More directional changes during shuttle running increase the physiological and perceptual load on female athletes, which also cause a greater reduction in knee extensor torque. These findings have implications for the effective conditioning and injury prevention of female team sport athletes.