High-intensity Running Performance Research Articles

Physical Fitness Tests as Predictors of High-Intensity Running Performance in Rugby.

Understanding the physical fitness elements that influence high-intensity running ability during rugby matches is crucial for optimizing player performance and developing effective training strategies. In this study, we aimed to investigate the relationships between various physical fitness components and high-intensity running ability in rugby. For this purpose, 60 Japanese university rugby players were randomized into four groups and two matches were played. The participants were monitored in two matches, and their running abilities were assessed using GPS sensors. The running time was divided into three running velocity categories: distance run at ≤5.4 km/h (low-intensity running); distance run at 5.5~17.9 km/h (medium-intensity running), and distance run at ≥18.0 km/h ≤(high-intensity running) and backs and forwards were evaluated separately. To determine which physical fitness test is more predictive of performance, we decided to correlate several physical test performances with the running time intensities during the matches. Independently of the position, the high-intensity running time correlated with the repeated sprint ability (RSA) and the 40 m sprint speed. The results suggest that RSA measured in the field is the most important high-intensity running ability predictor during a match for both positions.

The effect of acute manipulation of carbohydrate availability on high intensity running performance, running economy, critical speed, and substrate metabolism in trained Male runners

ABSTRACT Completing selected training sessions with reduced glycogen availability is associated with greater signalling and improved muscle oxidative capacity, although it may impact the overall quality of the session. We examined the effects of low carbohydrate availability on high intensity exercise performance, running economy, critical speed, and substrate metabolism. On two occasions, nine male runners (V̇O2peak 60.3 ± 3.3 mL.kg−1.min−1) completed a glycogen depletion protocol involving 90-min at 75%vV̇O2peak followed by 10 × 1-min at 110% vV̇O2peak. This was followed either by high (HIGH) or low (LOW) carbohydrate intake (>6 g.kg−1.day−1 and <50 g.day−1, respectively) until completion of a performance protocol on day 2 consisting of a series of time-trials (TT) (50m to 3000m) and physiological assessments. There were no differences between LOW and HIGH for any TT distance (mean TT performance times for LOW and HIGH were: 3000m TT 651.7 ± 52.8s and 646.4 ± 52.5s, 1500 m TT 304.0 ± 20.2s and 304.2 ± 22.1s, 400 m TT 67.64 ± 4.2s and 67.3 ± 3.8s, 50 m TT 7.27 ± 0.44s and 7.25 ± 0.45s, respectively, P > 0.05), though some athletes performed better in LOW (n = 5). While fat oxidation in LOW was significantly greater than HIGH (Δ0.32 ± 0.14 g.min−1; P < 0.001 at 14 km.h−1 and Δ0.34 ± 0.12 g.min−1 at 16 km.h−1; P < 0.01), running economy did not differ between trials (P > 0.05). Acute manipulation of carbohydrate availability showed immediate effects on substrate metabolism evidenced by greater fat oxidation without changes in RE. Acute low carbohydrate availability did not affect high intensity running performance across a range of distances. Highlights Acute manipulation of muscle glycogen availability using an exercise and dietary manipulation protocol did not affect subsequent high intensity running performance across a range of running distances. Reduced muscle glycogen resulted in a marked increase in fat oxidation in low glycogen condition but no changes in running economy or critical speed. Individual factors should be considered when prescribing high intensity sessions with restricted carbohydrate availability.

Ketone Monoester Ingestion Alters Metabolism and Simulated Rugby Performance in Professional Players

Ketone ingestion can alter metabolism but effects on exercise performance are unclear, particularly with regard to the impact on intermittent-intensity exercise and team-sport performance. Nine professional male rugby union players each completed two trials in a double-blind, randomized, crossover design. Participants ingested either 90 ± 9g carbohydrate (CHO; 9% solution) or an energy matched solution containing 20 ± 2g CHO (3% solution) and 590mg/kg body mass β-hydroxybutyrate monoester (CHO + BHB-ME) before and during a simulated rugby union-specific match-play protocol, including repeated high-intensity, sprint and power-based performance tests. Mean time to complete the sustained high-intensity performance tests was reduced by 0.33 ± 0.41s (2.1%) with CHO + BHB-ME (15.53 ± 0.52s) compared with CHO (15.86 ± 0.80s) placebo (p = .04). Mean time to complete the sprint and power-based performance tests were not different between trials. CHO + BHB-ME resulted in blood BHB concentrations that remained >2mmol/L during exercise (p < .001). Serum lactate and glycerol concentrations were lower after CHO + BHB-ME than CHO (p < .05). Coingestion of a BHB-ME with CHO can alter fuel metabolism (attenuate circulating lactate and glycerol concentrations) and may improve high-intensity running performance during a simulated rugby match-play protocol, without improving shorter duration sprint and power-based efforts.

Impact of probiotic supplementation on exercise endurance among non-elite athletes: study protocol for a randomized, placebo-controlled, double-blind, clinical trial

BackgroundSome probiotics appear to improve athletic performance, endurance, and recovery after intense exercise. Other formulations may provide performance-related benefits via immune and gastrointestinal functions in athletic individuals. However, few formulations have been studied for both types of effects among non-elite athletes. The primary objective of this study is to assess the ergogenic effects of a probiotic on high-intensity endurance running performance in non-elite runners. Secondary objectives include assessment of perceived exertion, blood chemistry, immune and stress biomarkers, cold and flu symptoms, and gastrointestinal health after the probiotic intervention.MethodsThis 9-week randomized, placebo-controlled, double-blind, parallel trial will assess the ergogenic effects of a probiotic (5 billion colony-forming units/day, for 6 weeks) in healthy, non-elite runners (N=32; 18–45 years). Participants will be monitored via daily and weekly questionnaires during the 2-week pre-baseline, 6-week intervention, and 1-week washout. Questionnaires will inquire about activity, muscle soreness, gastrointestinal symptoms, cold and flu symptoms, stool form and frequency, and adverse events. During the pre-baseline visit, maximal oxygen uptake (V̇O2 max) is assessed to set appropriate individualized workload settings for the treadmill time-to-exhaustion endurance tests. These time-to-exhaustion endurance running tests will be completed at an intensity of 85% VO2max at baseline and final visits. During these tests, self-perceived exercise effort will be rated via the Borg Rating of Perceived Exertion scale and finger sticks assessing capillary blood glucose and lactate concentrations will be collected every 3 min. Additional questionnaires will assess diet and motivation to exercise. Body composition will be assessed using air displacement plethysmography at the baseline and final visits. Hypotheses will be tested using two-sided tests, and a linear model and with a type I error rate of α=0.05. Primary and secondary outcomes will be tested by comparing results between the intervention groups, adjusting for baseline values.DiscussionThese results will build evidence documenting the role of probiotics on running endurance performance and physiological responses to exercise in non-elite athletes. Understanding the potential mechanisms of probiotic effects and how they mitigate the intestinal or immune discomforts caused by running could provide additional strategy means to help runners improve their performance.Trial registration numberClinicalTrials.govNCT04588142. Posted on October 19, 2020.Protocol version: July 2, 2021, version 1.2

Running Patterns in LaLiga Before and After Suspension of the Competition Due to COVID-19.

In the first wave of the COVID-19 outbreak (spring 2020), the first division of professional soccer in Spain (LaLiga) was suspended for 12 weeks as part of the lockdown imposed by the Spanish health authorities. Professional soccer players were confined to home for 8 weeks and then a retraining period of 4 weeks was set before the first competitive match. When competition was resumed, professional soccer teams competed in a congested calendar (11 matchdays in 39 days) while some in-game regulations were altered (up to 5 substitutions, refreshment pauses). The current research presents an analysis of running patterns before suspension and after resumption of LaLiga to determine how the lockdown affected players’ physical performance. To aid in this purpose, a pairwise comparison was performed of running patterns of the 2019–2020 vs. 2018–2019 season (i.e., control season). Using a two-way ANOVA (season x matchday), it was found that there was no main effect of the season on total running distance per match (P = 0.288) nor in the distances covered < 14.0 km/h (P = 0.294), at 21.0–23.9 km/h (P = 0.266), and at ≥ 24.0 km/h (P = 0.112). Only the distance at 14.0–20.9 km/h was affected by the season (P = 0.019) with a lower running distance on matchday 34 in the 2019–2020 vs. 2018–2019 season. The number of substitutions (from 2.9 to 4.5 substitutions per game; P < 0.001) and match duration (96 vs. 100 min; P < 0.001) significantly increased after resumption respect to the previous season. These data suggest that high-intensity running performance of professional soccer teams was maintained after the resumption of the competition while the alterations likely aided in the in-game regulations facilitated the maintenance of soccer physical performance.

A Mixed-Method Approach of Pre-Cooling Enhances High-Intensity Running Performance in the Heat.

We investigated whether single or combined methods of pre-cooling could affect high-intensity exercise performance in a hot environment. Seven male athletes were subjected to four experimental conditions for 30 min in a randomised order. The four experimental conditions were: 1) wearing a vest cooled to a temperature of 4 ℃ (Vest), 2) consuming a beverage cooled to a temperature of 4 ℃ (Beverage), 3) simultaneous usage of vest and consumption of beverage (Mix), and 4) the control trial without pre-cooling (CON). Following those experimental conditions, they exercised at a speed of 80% VO2max until exhaustion in the heat (38.1 ± 0.6 ℃, 55.3 ± 0.3% RH). Heart rate (HR), rectal temperature (Tcore), skin temperature (Tskin), sweat loss (SL), urine specific gravity (USG), levels of sodium (Na+) and potassium (K+), rating of perceived exertion (RPE), thermal sensation (TS), and levels of blood lactic acid ([Bla]) were monitored. Performance was improved using the mixed pre-cooling strategy (648.43 ± 77.53 s, p = 0.016) compared to CON (509.14 ± 54.57 s). Tcore after pre-cooling was not different (Mix: 37.01 ± 0.27 ℃, Vest: 37.19 ± 0.33 ℃, Beverage: 37.03 ± 0.35 ℃) in all cooling conditions compared to those of CON (37.31 ±0.29 ℃). A similar Tcore values was achieved at exhaustion in all trials (from 38.10 ℃ to 39.00 ℃). No difference in the level of USG was observed between the conditions. Our findings suggest that pre-cooling with a combination of cold vest usage and cold fluid intake can improve performance in the heat.

Internal training load and fitness profile between adult team versus junior team soccer players

The aim of the present study was to compare the fitness profiles and internal training loads between senior team and academy team soccer players during an in-season phase. Twenty-two professional soccer players from the senior team (n=12; 28.3&lt;img width="12" alt="" height="20"&gt; 2.0 years) and under 19 (U19) team (n=10; 18.0&lt;img width="12" alt="" height="20"&gt; 0.4 years) of the same club participated in the present study. High-intensity running performance, acceleration, maximal sprint, and change of direction (COD) ability were all tested during the mid-season break of a competitive season. Session rating of perceived exertion (sRPE) reflecting the internal training load during the entire first half of the season was being documented daily. Senior players showed small to moderate superiority in COD (1.8%, 90% confidence intervals [CI, -3.2; 7.1], ES: 0.24 [-0.44; 0.92]), maximal sprint (2.3%, [0.0; 4.7], ES: 0.81 [0.00; 1.63]) and acceleration (3%, [0.2; 5.8], ES: 0.96 [0.06; 1.85]). The U19 showed small better high-intensity intermittent running fitness (2.5%, [-1.2; 6.3], ES: 0.39 [-0.20; 0.97]). When analyzing internal training loads (from M-3 to M+3), the U19 showed small to very large higher sRPE values for all days (range; 8.2%; 229.3%, [-8.1; 328.3], ES range; 0.25; 2.70, [-0.26; 3.3]), except for match days (M), on which unclear trivial difference was observed (-1.5%, [-9.6; 7.5], ES -0.09 [-0.65; 0.46]). Our results showed that senior players and youth players had different fitness profiles and internal training loads during the first half of a competitive season; this should be taken into consideration when designing specific and individualized recovery and training sessions.

Playing position specifics of associations between running performance during the training and match in male soccer players

Background: The relationship between the training load and game load considering soccer playing positions has not been sufficiently examined. Objective: The aim of this study was to examine the position-specific associations between running performance (RP) during the training and match in professional-level male soccer. Methods: The RPs of 15 players (age 23.57 ± 2.84 years, body height 181.9 ± 5.17 cm, body mass 78.36 ± 4.18 kg) were measured by the Global Positioning System over one half-season of the highest-level Croatian soccer competition and assessed according to their playing positions: central defenders (n = 22), fullbacks (n = 23), wide midfielders (n = 29), wingers (n = 6), and forwards (n = 12). Variables included the total distance covered; the distance covered by low intensity running, running, high-speed running, sprinting, and high intensity running; and the number of accelerations, high-intensity accelerations (HIA), decelerations, and high-intensity decelerations (HID). Results: Analysis of variance revealed significant differences in high-speed running, HID, and HIA (p = .01, all highest in forwards), and sprinting (p = .01, highest in the wide midfielders). The HIA and HID at training were significantly (p = .04 and .01, respectively) correlated (r = .42 and .52) with the corresponding match RP in fullbacks. The high-intensity running (high-speed running + sprinting), running, HIA and HID performance values were significantly correlated (r = .64, .52, .59, and .52, respectively; all p = .01) with the corresponding running performances from matches in central midfielders. Conclusions: Structure-specific training is highly recommended for some playing positions. The information obtained can be used to improve soccer training programs.

Effects of manipulating player numbers on technical and physical performances participating in an Australian football small-sided game

ABSTRACT In Australian Football (AF), small-sided games (SSGs) are used extensively to replicate particular technical, tactical or physiological responses. Whilst research on SSGs has been extensive in soccer, in AF it has been limited to agility demands and exploring the effect of field dimensions on technical skill (i.e., handballing) and physical responses of senior athletes. Therefore, this study investigated the effect of four different SSG player number conditions (5v5, 5v6, 6v6, 7v7) on the technical (e.g., kicking) and physical (i.e., odometer, m-min−1, max velocity and percentage of high intensity running) performance outcomes in 22 sub-elite youth AF players. Particular constraints were applied to the SSG to ensure the focus was on kicking (i.e., after each handball a kick must be performed). The results of this study demonstrate when more technical events are required under more pressured situations (i.e., physical and time) the 5v6 condition appears to be most appropriate. However, when the focus is on kicking to a contested possession (i.e., kicking to leading or covered players) balanced player numbers (e.g., 6v6) would appear optimal. Alternatively, when the SSG focus is on increasing physiological demands (i.e., m.min−1) lower player density conditions (i.e., 5v5) appear more suitable.

Physical capacities related to running performance during simulated matches in young futsal players

This study aimed to verify the relationship between physical capacities and distance covered during simulated matches in young futsal players. Sixteen under-19 male futsal players of regional level (age 18.1 ± 0.96 years, body mass 67.4 ± 9.7 kg, height 176 ± 5 cm) participated in this study. Players performed the futsal intermittent endurance test (FIET), maximal shuttle run test (MST), squat jump and countermovement jump tests. Two simulated futsal matches were performed to assess the distance covered at different intensities. Pearson correlation and multiple linear regression were used for statistical analysis. The main results showed significant correlation of peak velocity obtained in the FIET (PVFIET) (15.8 ± 0.6 km h−1) with distance covered per minute (r = 0.85, p < 0.01) and distance covered at high intensity (r = 0.60, p = 0.03). Fatigue index (5.6 ± 1.9%) correlated with the distance covered at high intensity (r = − 0.70, p = 0.01) and percentage of distance covered in sprint (r = − 0.69, p = 0.01). The PVFIET and best time in the MST (8.48 ± 0.38 s) explained 50% of the variance in the total distance covered; whereas, the PVFIET explained 73% of the distance covered per minute. The fatigue index was a negative predictor of high-intensity running and explained 40% of its variance. PVFIET is one of the most important variables capable of predicting physical futsal match-related performance. Moreover, the capacity to resist fatigue during repeated sprints and the maximal sprinting speed of players were related to high-intensity running performance during the matches.

Effect of Heat Stress on Measures of Running Performance and Heart Rate Responses During a Competitive Season in Male Soccer Players.

Coker, NA, Wells, AJ, and Gepner, Y. The effect of heat stress on measures of running performance and heart rate responses during a competitive season in male soccer players. J Strength Cond Res 34(4): 1141-1149, 2020-Measures of running performance and heart rate (HR) responses to match play during 3 different heat stress (HS) conditions were assessed in 7 National Collegiate Athletic Association (NCAA) Division I male soccer players. Total distance and distance covered within distinct velocity zones (walking [WALK], jogging [JOG], low-speed running, high-speed running, sprinting [SPRINT], low-intensity running [LIR], and high-intensity running [HIR]) were assessed using global positioning system units for more than 12 matches. Heat stress was monitored during each match, and matches were defined as low (HSlow, n = 4), moderate (HSmod, n = 4), or high (HShigh, n = 4) HS. Minutes played were significantly different across HS conditions (p = 0.03). Therefore, distance covered within each movement velocity was assessed relative to minutes played and as a percentage of total playing time. WALKrel was significantly greater during HShigh compared with HSlow (p = 0.035). LIRrel was significantly greater during HSmod (p = 0.015) compared with HSlow. A trend was observed for %WALK being higher during HShigh compared with HSlow (p = 0.066). %LIR was significantly greater during HShigh compared with HSlow (p = 0.048). High-intensity running was not significantly different across HS conditions. Percent of time spent >85% HRmax was significantly greater during HShigh (p = 0.002) and HSmod (p < 0.001) compared to HSlow. Percent of time spent between 65-84% HRmax was significantly greater during HSlow compared to HShigh (p < 0.001). Results indicate that HS resulted in increased LIR and %HR≥85, while HIR was maintained. High-intensity running performance may be conserved through decreased playing time or the adoption of pacing strategies. This may assist coaches in altering player management strategies to optimize team performance.

Movement Demands and Injury Characteristics in Under-20-Years University Rugby Union Players.

Rugby union is a field-based collision sport with high injury rates. Associations between injury characteristics and global positioning system-derived movement demands in rugby union athletes are yet to be investigated. To investigate associations between match injuries and movement demands, anthropometrics, and physical performance in under-20-years university-level rugby union players. Descriptive epidemiology study. Competition season. Rugby union players (n = 34, age = 19.3 ± 0.6 years) from a university club were recruited. Acute medical attention non-time-loss (NTL), medical-attention time-loss (TL), and total medical-attention (MA) injuries sustained were recorded. Principal component (PC) analysis was performed on player-movement demand variables to identify independent-movement demand components. Pearson correlation and bivariate linear regression were used to test associations between match injuries and PCs. Anthropometric and physical performance measures were tested as predictors of match injuries using a forward stepwise multiple regression analysis. Backs had lower anthropometric and performance measures than forwards (P < .05), whereas forwards performed fewer weekly movement demands than backs (P < .05). Increases in body mass and skinfold thickness were associated with more injuries (P < .05). Principal component analysis revealed 3 PCs representing overall performance, high-intensity running (HIR) performance, and impacts. Increases in HIR were associated with decreases in NTL upper limb and trunk (r = -0.32, P = .03), NTL musculoskeletal (r = -0.36, P = .05), NTL total (r = -0.46, P < .01), TL musculoskeletal (r = -0.30, P = .05), MA musculoskeletal (r = -0.41, P < .01), and MA total (r = -0.48, P < .01) injuries. Increases in impacts were associated with increased TL (r = 0.32, P = .03) and MA (r = 0.33, P = .03) head or neck injuries. Backs experienced greater weekly movement demands than forwards. Increases in HIR demands were associated with decreased acute injuries in university rugby players. Increases in impacts were associated with more acute head or neck injuries. Positional differences in movement demands, anthropometrics, and physical performance highlight the need for position-specific training.

Associations Between Selected Training-Stress Measures and Fitness Changes in Male Soccer Players.

To investigate the relationship between accumulated global positioning system-accelerometer-based and heart rate-based training metrics and changes in high-intensity intermittent-running capacity during an in-season phase in professional soccer players. Eleven male professional players (mean [SD] age 27.2 [4.5]y) performed the 30-15 Intermittent Fitness Test (30-15IFT) before and after a 5-wk in-season training phase, and the final velocity (VIFT) was considered their high-intensity intermittent-running capacity. During all sessions, Edwards training impulse (Edwards TRIMP), Banister TRIMP, Z5 TRIMP, training duration, total distance covered, new body load (NBL), high-intensity running performance (distance covered above 14.4km·h-1), and very-high-intensity running performance (distance covered above 19.8km·h-1) were recorded. The players' VIFT showed a most likely moderate improvement (+4.3%, 90% confidence limits 3.1-5.5%, effect size 0.70, [0.51-0.89]). Accumulated NBL, Banister TRIMP, and Edwards TRIMP showed large associations (r = .51-.54) with changes in VIFT. A very large relationship was also observed between accumulated Z5 TRIMP (r = .72) with changes in VIFT. Large to nearly perfect within-individual relationships were observed between NBL and some of the other training metrics (ie,Edwards TRIMP, Banister TRIMP, training duration, and total distance) in 10 out of 11 players. Heart rate-based training metrics can be used to monitor high-intensity intermittent-running-capacity changes in professional soccer players. The dose-response relationship is also largely detected using accelerometer-based metrics (ie,NBL) to track changes in high-intensity intermittent-running capacity of professional soccer players.

Lower-Body Power Relationships to Linear Speed, Change-of-Direction Speed, and High-Intensity Running Performance in DI Collegiate Women's Basketball Players.

Basketball players need to sprint and change direction, and lower-body power (often measured by jump tests) should contribute. How different jumps relate to linear and change-of-direction (COD) speed, and high-intensity running has not been analyzed in Division I (DI) collegiate women’s basketballers. Twelve players completed the vertical jump (VJ), two-step approach jump (AppJ), and standing broad jump (SBJ). Average (AvgP) and peak power (PeakP), and PeakP: body mass (P:BM) were derived from VJ height; relative SBJ was derived from SBJ distance. Players also completed: 10 m and ¾ court sprints (linear speed), the pro-agility shuttle (COD speed), and the Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1; high-intensity running). Pearson’s correlations (p < 0.05) calculated relationships between the jump and running tests. The AppJ correlated to the ¾ court sprint and pro-agility shuttle (r = -.663 to -.805). AvgP and PeakP correlated to the 10 m sprint, ¾ court sprint, and pro-agility shuttle (r = .589-.766). P:BM and relative SBJ correlated with all running tests (linear and COD speed r = -.620 to -.805; YYIRT1 r = .622.803). The AppJ stresses the stretch-shortening capacities of the legs, and this quality is important for faster linear and COD speed. AvgP and PeakP are influenced by body mass; while larger athletes produce greater power, they also may display slower 10 m sprint and pro-agility shuttle times, and lesser YYIRT1 performance. Strength coaches should ensure players can generate high relative power (i.e. P:BM, relative SBJ) for faster linear and COD speed, and high-intensity running.

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 (VO2max) 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 VO2max. 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.

Relationship of Training Load with High-intensity Running in Professional Soccer Players.

This study determined the training load (TL) and its relationship with high-intensity running performance across the season in professional soccer players. The TL, YoYo Intermittent Recovery Test Level 2 (YYIR 2) and repeated sprint ability (RSA) were monitored in 29 players (age 26.2±3.8 years, height 173.6±5.6 cm, body mass 68.5±8.6 kg). In the mid in-season (MS), Lucia TRIMP (TRIMPL) was inversely correlated with YYIR 2 (r=-0.6, p<0.05), with total distance (TD), work-rate (WR), low-intensity distance (LID) and player load (PL) showing correlation with YYIR 2 (r=0.81, 0.77, 0.88, 0.67; p<0.05) in the late in-season (LS). In pre-season (PS), TD, WR and moderate-intensity distance (MID) were correlated with YYIR 2 (r=0.65, 0.80, 0.83, p<0.05), whereas in early in-season (ES), TD, WR, LID were correlated with YYIR 2 performance (r=0.58, 0.67, 0.55, p<0.05). There was no significant relationship (p>0.05) between TL and RSA. The findings showed the volume, intensity and types of TL accrued influences the relationship with physical performance that suggest the significance of phase-specific monitoring of TL for maximizing performance in soccer players.

Running Demands and Activity Profile of the New Four-Quarter Match Format in Men's Field Hockey.

Ihsan, M, Yeo, V, Tan, F, Joseph, R, Lee, M, and Aziz, AR. Running demands and activity profile of the new four-quarter match format in men's field hockey. J Strength Cond Res 35(2): 512-518, 2021-This study determined the running demands of men's field hockey with regards to the revised four-quarter match format. Twenty-eight male field hockey players were equipped with global positioning system units while competing in 14 competitive international games over a 1-year period. All matches allowed for unlimited substitutions, and consisted of four 15-minute quarters (i.e., Q1-Q4). A progressive decline in total distance (TD) was observed in Q2 (2,072 ± 141 m) to Q4 (2,055 ± 212 m) compared with Q1 (2,171 ± 195 m, p < 0.05). However, the decline in TD was due to decreases in low-intensity activity (<15 km·h-1, p < 0.05), as high-intensity running (HIR; >15 km·h-1) distances were similar throughout Q1-Q4 (p = 0.263). Positional data demonstrated a similar profile, where significant decreases in TD, but not in HIR, was observed across all playing positions at some point over the 4 quarters (p < 0.05). DEF accumulated the lowest amount of TD (7,631 ± 753 m), HIR (2,257 ± 498 m), and high-intensity decelerations (60 ± 9, >-2m·s-2) compared with MID and FWD (p < 0.05). By contrast, FWD performed the highest amount of HIR (3,090 ± 565 m) and high-intensity accelerations (110 ± 9, >2 m·s-2) compared with MID and DEF (p < 0.05). In conclusion, our results showed that although there was a progressive decline in TD over the 4 quarters of match play, high-intensity running performance (i.e., HIR and high-intensity acceleration) was maintained throughout the match regardless of playing position.

Speed-based high-intensity interval approach as an alternative to heart rate training

The aims of this study were to: 1) compare the effects of speed-based versus heart-rate-based high-intensity interval training (HIT) on changes in high-intensity intermittent running performance, and 2) examine between-group differences in heart rate (HR) and rating of perceived exertion (RPE) responses during the training sessions. Sixteen female students were divided into the HR-based (n=8, M±SD, age 17.3±0.2 years, body mass, 59.2±5.7 kg, and body height, 167.8±2.2 cm) and speed-based (n=8, age 17.2±0.3 years, body&amp;nbsp;mass, 57.7±6.4 kg, and body height, 171.0±5.1 cm) groups before commencing the HIT intervention. After completing five weeks of HIT, both the HR-based and speed-based groups showed most likely moderate enhancement in high-intensity intermittent running performance (+9%, 90% confidence limits [CL] [6.4; 11.7]; standardized change [ES] +1.04 [0.75; 1.33]) and (+9.2%, [6.0; 12.5]; +1.09 [0.73; 1.46]), respectively. However, the difference between the experimental groups with regards to changes in high-intensity running performance was trivial. Between-group differences of weekly average HR and RPE responses showed trivial to moderate (ES range; -0.95; 0.15) and moderate to very large (ES: -0.63; -2.88) values, respectively. Although it seems that both the speed-based and HR-based HIT approaches have some limitations when implementing for HIT individualization, using the speed reached at the end of the 30-15 Intermittent Fitness test (VIFT) seems to elicit the same performance enhancement, but with lower psychophysiological responses during short-term interventions.

The Effect of Natural or Simulated Altitude Training on High-Intensity Intermittent Running Performance in Team-Sport Athletes: A Meta-Analysis.

While adaptation to hypoxia at natural or simulated altitude has long been used with endurance athletes, it has only recently gained popularity for team-sport athletes. To analyse the effect of hypoxic interventions on high-intensity intermittent running performance in team-sport athletes. A systematic literature search of five journal databases was performed. Percent change in performance (distance covered) in the Yo-Yo intermittent recovery test (level 1 and level 2 were used without differentiation) in hypoxic (natural or simulated altitude) and control (sea level or normoxic placebo) groups was meta-analyzed with a mixed model. The modifying effects of study characteristics (type and dose of hypoxic exposure, training duration, post-altitude duration) were estimated with fixed effects, random effects allowed for repeated measurement within studies and residual real differences between studies, and the standard-error weighting factors were derived or imputed via standard deviations of change scores. Effects and their uncertainty were assessed with magnitude-based inference, with a smallest important improvement of 4% estimated via between-athlete standard deviations of performance at baseline. Ten studies qualified for inclusion, but two were excluded owing to small sample size and risk of publication bias. Hypoxic interventions occurred over a period of 7-28days, and the range of total hypoxic exposure (in effective altitude-hours) was 4.5-33kmh in the intermittent-hypoxia studies and 180-710kmh in the live-high studies. There were 11 control and 15 experimental study-estimates in the final meta-analysis. Training effects were moderate and very likely beneficial in the control groups at 1week (20±14%, percent estimate,±90% confidence limits) and 4-week post-intervention (25±23%). The intermittent and live-high hypoxic groups experienced additional likely beneficial gains at 1week (13±16%; 13±15%) and 4-week post-intervention (19±20%; 18±19%). The difference in performance between intermittent and live-high interventions was unclear, as were the dose of hypoxia and inclusion of training in hypoxia. Hypoxic intervention appears to be a worthwhile training strategy for improvement in high-intensity running performance in team-sport athletes, with enhanced performance over control groups persisting for at least 4weeks post-intervention. Pending further research on the type of hypoxia, dose of hypoxia and training in hypoxia, coaches have considerable scope for customising hypoxic training methods to best suit their team's training schedule.

The Influence of Rotations on Match Running Performance in Female Australian Football Midfielders.

With female Australian football (AF) gaining popularity, understanding match demands is becoming increasingly important. The aim of this study was to compare running performances of rotated and whole-quarter state-level female AF players during match quarters. Twenty-two state-level female AF midfielders wore Global Positioning System units during 14 games to evaluate activity profiles. The Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) was used as a measure of high-intensity running ability. Data were categorized into whole quarter, rotation bout 1, and rotation bout 2 before being further divided into quartiles. Players were separated into high- or low-Yo-Yo IR1 groups using a median split based on their Yo-Yo IR1 performance. Short (4-6 min), moderate (6-12 min), and long (12-18 min) on-field bout activity profiles were compared with whole-quarter players. High Yo-Yo IR1 performance allowed players to cover greater relative distances (ES = 0.57-0.88) and high-speed distances (ES = 0.57-0.86) during rotations. No differences were reported between Yo-Yo IR1 groups when players were required to play whole quarters (ES ≤ 0.26, likelihood ≤64%). Players who were on field for short to moderate durations exhibited greater activity profiles than whole-quarter players. Superior high-speed running ability results in a greater activity profile than for players who possess lower high-speed running ability. The findings also highlight the importance of short to moderate (4-12 min) rotation periods and may be used to increase high-intensity running performance within quarters in female AF players.