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Original Research

The Influence of Exercise-to-Rest Ratios on Physical and Physiological Performance During Hurling-Specific Small-Sided Games

Malone, Shane; Hughes, Brian; Collins, Kieran

Author Information
Journal of Strength and Conditioning Research: January 2019 - Volume 33 - Issue 1 - p 180-187
doi: 10.1519/JSC.0000000000001887
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Abstract

Introduction

Hurling is one of the national sports of Ireland and has been described as one of the world’s most dynamic and skilled field games (7,28). It is a high-speed dynamic team sport where 2 teams consisting of 1 goalkeeper and 14 outfield players compete on an average pitch dimension of 140 × 88 m with a relative player area of 410 m2 (20,21,28). The sport requires players to engage in total distances of 7,604 ± 510 m, interspersed with 1,623 ± 149 m of high-speed distance (m; ≥17 km·h−1), and 300 ± 47 m of sprint distance (m; ≥22 km·h−1) (22,24). In essence, this is a sport that requires players to have a high level of aerobic endurance in order to generate and maintain repeated high-speed efforts with short work-to-rest ratios during match play (22,24). Therefore, within hurling, physical conditioning strategies that reflect the demands of match play and allow for an increase in aerobic capacity are of the upmost importance for coaches (18,19). Previously, improvements in aerobic capacity have been associated with improvements in match-play performances within team-sport cohorts (15). Furthermore, increased aerobic capacity seems warranted as it allows players to recover more efficiently between high-speed efforts (4).

The use of small-sided games (SSG) is now commonplace within team sports (5,6,8,13,20). Indeed, SSGs represent a major component of the hurling training process (18,20,21). Currently, SSGs are a very popular training methodology within hurling (18,20,21) as they offer the opportunity to develop technical and tactical elements concurrently with specific fitness capacities such as endurance (aerobic and anaerobic), strength, and agility (25). These games have been shown to replicate the relative match-play demands of competitive hurling match play (21). Previously, it has been demonstrated that prescriptive variables can influence the physical and physiological demands experienced by players during SSGs. Typically, coaches will attempt to change the training stimulus during SSGs through altering the pitch area (21), player number (20), the game type (20), coach encouragement, the competitive nature of the SSG (18), and rule changes (20). However, little is known as to the impact that different work-to-rest ratios has on the exercise intensity and physical running demands within hurling-based SSGs with all of the aforementioned investigations employing a 1:1 exercise-to-rest ratio (18,20,21).

The ability to maintain high exercise intensity and high-speed movements across multiple SSG bouts is dependent on the recovery from the previous SSG (25,26). This is influenced by both the exercise intensity during the SSG bout, and the duration of the rest after the SSG bout (26,30). The best is represented by a SSG exercise-to-rest ratio, which places the time of the SSG relative to the rest period postcompletion of the SSG (4,16). During recovery from SSGs, oxygen consumption remains elevated to replenish the intramuscular high-energy phosphates required to perform high-intensity exercise, to pre-exercise levels (4,16,26). Previously, within soccer, different recovery durations have been observed between bouts of SSGs. Rampinini et al. (27) used a 3-minute recovery between both 3- and 6-a-side SSG formats with Koklu et al. (16) applying a 2-minute recovery period between bouts in 1-a-side up to 4-a-side games with these recovery periods shown to impact both the physical and physiological demands of SSG. With regard to hurling, Malone et al. (20) have applied 1:1 exercise-to-rest ratios during SSGs with these games shown to replicate the relative demands of hurling match play. Recently, within soccer, Koklu et al. (16) reported that SSGs with smaller work-to-rest ratios resulted in players attaining higher percentages of heart rate max (91.4 ± 2.3%) and heart rate reserve (87.7 ± 3.1%) when contrasted against larger work-to-rest ratios (88.6 ± 3.7 %HRmax and 83.6 ± 5.5 %HRres). Additionally, within this study, players were observed to cover greater low-speed distances with reduced distances at higher speeds (≥18.0 km·h−1) when contrasted against larger exercise-to-rest ratios. The above results are in agreement with McLean et al. (25) who observed that shortened exercise-to-rest ratios resulted in higher HR responses during SSGs. These results are in contrast with previous research which reported no differences in HR or GPS variables when short or long exercise-to-rest ratios were used during SSGs (5). These results show that a trade-off between SSGs’ intensity exists when considering exercise-to-rest ratios, suggesting that physiological intensity can come at the cost of high-speed actions during SSGs. However, many of these investigations have taken place in sports that are far removed from hurling with regard to player movement patterns and ball movement patterns. Indeed, within hurling, the ball can travel at 100 m·s−1 (18,20), thus impacting the physical and physiological dynamic within the confined spaces that are often prescribed for SSGs.

Therefore, given the specific game dynamics of hurling, and the conflicting results exist on the potential impact of exercise-to-rest ratios on the physical and physiological demands during SSGs. Given these conflicting findings and with no previous literature on exercise-to-rest ratios completed on hurling-specific SSGs. There is a need for coaches to understand the potential impact of different exercise-to-rest ratios on SSGs’ demands. Therefore, the aim of the current study was to provide an insight to the potential impact that different exercise-to-rest ratios have on hurling-specific SSGs with respect of physical and physiological demands.

Methods

Experimental Approach to Problem

Thirty-four hurling players competing at the top level of club hurling, and who had recently won a championship (age: 25.5 ± 3.2 years; height: 178.9 ± 3.2 cm; body mass: 78.5 ± 4.5 kg), volunteered for the study during a 16-week competitive period of the 2015 season (March–June). During the observational period, a total of 2,080 individual SSG drill observations were undertaken on outfield players with a median of 85 observations per player range (40–85). Four different exercise-to-rest ratios were observed during the study period. Specifically, 2:1 (player observations, n = 520), 1:1 (layer observations, n = 520), 1:2 (player observations, n = 520), and 1:3 (layer observations, n = 520), exercise-to-rest ratios were observed. During the observation period, players completed six 4-minute bouts of hurling-specific SSGs (60 × 20 m) within training. During SSGs, the player number (4 v 4), relative player area (150 m2), and game rules were standardized for each specific work-to-rest ratio. The objective of the SSG was to keep possession of the ball and score in a designated end-zone area at the end of the SSG pitch. Teams were selected based on players playing position to best replicate the man-marking nature of competitive hurling match play (6,18,20,21). Each SSG was performed in a randomized continuous manner during the observational period to remove the effect of SSG ordering on physiological and running performance (18). During the SSGs, full competition rules were applied. Each SSG was completed 6 times (6 bouts) to allow for an effect to be identified between different exercise-to-rest ratios on subsequent bouts. Additionally, multiple replacement balls were made available by prompt replacement when the ball was hit out of play (18). During the rest periods, players engaged in passive technical drills consisting of striking to hand or hurl for the designated rest period at 65% of HRmax. Before the observation period, the specific SSG was frequently performed by players in a number of sessions (n = 15) to ensure players were familiar with the aims and structure of play during the SSG. All training sessions were performed on the same pitch. All SSGs were completed after a standardized warm-up of 20 minutes containing both technical and dynamic movements. Specifically, at the start of the warm-up, players engaged in elements of dynamic stretching and low-intensity running. Players were then split into groups of 6 and completed 6 repeated shuttles over 45 m to expose players to maximal speed. After this, players began technical elements of the warm-up; specifically, this included conditional elements with regard to the number of ball touches authorized per individual in possession which was fixed for a period of time (from 1 touch to 6 touches). Finally, players engaged in a small element of free play within a condensed pitch of 20 × 20 m for 3 minutes. During the SSG, all players wore GPS (4-Hz; VX Sport, Issue: 330a, Firmware: 3.26.7.0) and HR belts (Polar Team Sport System; Polar Electro Oy) to best assess players’ physical and physiological performance during the specific SSG. All training took place between 18:00 and 20:00 hours to avoid any circadian variation in physical and physiological performance (9). Players were requested to abstain from strenuous physical activity in the 24–48 hours before training. All players were advised to maintain their normal diet, with special emphasis being placed on the intake of fluids and carbohydrates. During rest periods, the players were allowed to drink fluids at libitum.

Subjects

Thirty-four (n = 34) hurling players competing at the top level of club hurling (mean ± SD: age: 25.5 ± 3.2 years; height: 178.9 ± 3.2 cm; body mass: 78.5 ± 4.5 kg) took part in the study during the 2015 in-season competition period. Players were part of the same team, a Division 1 team that had recently won the county championship and had a minimum playing experience of 4 years (range = 4–10 years playing experience). The players trained three times a week throughout the investigation period. After ethical approval, participants attended an information evening where they were briefed about the purpose, benefits, and procedures of the study. Written informed consent and medical declaration were obtained from participants in line with the procedures set by the Institute of Technology Tallaght research ethics committee.

Procedures

Running Performance Analysis

During all SSGs, participants wore an individual GPS unit (VX Sport, Issue: 330a, Firmware: 3.26.7.0) sampling at 4 Hz and containing a triaxial accelerometer and magnetometer in all training sessions. The GPS unit (mass: 76 g; 48 × 20 × 87 mm) was encased within a protective harness between the player's shoulder blades in the upper thoracic-spine region. Fifteen minutes before the commencement of training, the GPS device was fixed to the athlete, to establish a satellite lock training (17). The validity and accuracy of this specific unit has previously been reported (3,23). Specifically, the VX Sport GPS unit has more recently been examined by Malone et al. (23) for accuracy and reliability during intermittent activity. Test-retest (7 days apart) reliability for total distance covered, maximum speed, and average speed were quantified. Systematic differences were examined using a paired t-test on the test-retest data, and revealed no significant differences for the total distance covered (300.5 ± 3.3; 303.6 ± 5.6 m), maximum speed (23.9 ± 1.9; 24.1 ± 1.3 km·h−1), and average speed (10.2 ± 1.0; 10.2 ± 0.9 km·h−1). The typical error (TE ± 95% confidence interval [CI]) was 0.84 ± 0.3 for total distance covered, 0.75 ± 0.26 for maximum speed, and 0.55 ± 0.19 for average speed, respectively. The coefficient of variation (CV% ± 95% CI) was 1.0 ± 0.4 for the total distance covered, 4.2 ± 1.5 for maximum speed, and 4.4 ± 1.5 for average speed, respectively. Proprietary software provided instantaneous raw velocity data at 0.25 second intervals, which was then exported and placed into a customized Microsoft Excel spreadsheet (Microsoft, Redmond, WA, USA) retrospectively, post-training. The spreadsheet allowed analysis of distance covered (m) and speed calculated (km·h−1) in the following categories: total distance; high speed running distance (m; ≥17 km·h−1); very high-speed running distance (m; ≥ 22 km·h−1); total acceleration (n), acceleration distance (m) and peak velocity (km·h−1).

Physiological Performance Analysis

Physiological performance during SSG was assessed on the basis of heart rate (HR) analysis (11) which was recorded every 5 seconds using a telemetric device (Polar Team Sport System; Polar Electro Oy). The HR maximum (HRmax) of each player was determined by means of the Yo-Yo intermittent recovery test level 2 (Yo-YoIR2) as completed in previous Hurling research on SSGs (2,18). The mean HRs (HRmean) for each SSG were recorded and expressed as a percentage (%) of individual maximum to provide an indication of the overall intensity of the SSG in relation to the mean and maximum HR obtained in the Yo-YoIR2 (HRmean and %HRmax). The CV of HR responses (%HRmax) during SSGs has been reported as 1.3–4.8% (27).

Statistical Analyses

Shapiro-Wilk test was performed for the evaluation of normality distribution. A repeated-measures ANOVA was conducted on the physical (GPS) and physiological demands (HR) of the SSG (dependant variables) according to exercise-to-rest ratio (2:1, 1:1, 1:2, 1:3) and number of bouts (1–6) (independent variables). A Bonferoni posthoc test was conducted in order to determine significance between conditions. Statistical analyses were performed using SPSS version 22 for Windows 7 (SPSS, Chicago, IL, USA). Data is expressed as mean (90% confidence limits [CL]) unless stated otherwise. Statistical significance was set at p ≤ 0.05. To make inferences about true values of the difference in the physical and physiological performance qualities of each pitch dimension Cohen effect size (d) was reported. The uncertainty was expressed as d ± 90% CL. Effect sizes of <0.2, 0.2–0.6, 0.6–1.2, and 1.2–2.0 were considered trivial, small, moderate, and large, respectively (14).

Results

Selected running performance variables are reported in Table 1. There were nonsignificant differences between exercise-to-rest ratios for total distance (mean difference = 10 ± 5 m; p = 0.541; d = 0.1 ± 0.2; trivial), and peak velocity (mean difference = 1.5 ± 0.2 km·h−1; p = 0.641; d = 0.3 ± 0.2; small) during all bouts of SSG. Exercise-to-rest ratios of 2:1 (mean difference = −65 ± 25 m; p = 0.001; d = 0.65 ± 0.12; moderate), and 1:1 (mean difference = −45 ± 15 m; p = 0.035; d = 0.43 ± 0.12; small), resulted in significant reductions in high-speed distance (Figure 1), very high-speed distance, and acceleration distance (Table 1). Exercise-to-rest ratios of 1:2 (mean difference = 40 ± 27 m; p = 0.041; d = 0.63 ± 0.21; moderate) and 1 to 3 (Mean difference = 94 ± 55 m; p = 0.011; d = 1.23 ± 0.22; large) resulted in increased high-speed distance and very high-speed distance but only after the third bout. When accelerations (mean difference = 4 ± 2; p = 0.841; d = 0.11 ± 0.02; trivial) and acceleration distance (mean difference = 10 ± 8 m; p = 0.754; d = 0.05 ± 0.04; trivial) were considered, there was a nonsignificant difference between these variables for all exercise-to-rest ratios during the first 3 bouts of SSG. After the third bout, exercise-to-rest ratios of 1:2 (mean difference = 10 ± 8 m; p = 0.754; d = 0.05 ± 0.04; trivial), and 1:3 (mean difference = 10 ± 8 m; p = 0.754; d = 0.05 ± 0.04; trivial), resulted in increased number of accelerations. Significant reductions in these variables were observed for 2:1 (mean difference = 8 ± 6; p = 0.034; d = 0.30 ± 0.24; moderate), and 1:1 (mean difference = 6 ± 5; p = 0.004; d = 0.35 ± 0.04; moderate) exercise-to-rest ratios. The effect of different work-to-rest ratios on SSG exercise intensity (%HRmax) is reported in Figure 2. There was a significant bout-to-bout increase in %HRmax independent of exercise-to-rest ratio (mean difference: 8 ± 3%; p = 0.005; d = 0.25 ± 0.04; small). Exercise-to-rest ratios of 2:1 (mean difference: 10 ± 4%; p = 0.035; d = 0.65 ± 0.14; moderate), and 1:1 (mean difference: 9 ± 3%; p = 0.045; d = 0.65 ± 0.24; moderate), resulted in significantly higher %HRmax during all SSG bouts, however, exercise-to-rest ratios of 1:2 (mean difference: 6 ± 2%; p = 0.455; d = 0.25 ± 0.04; small), and 1:3 (mean difference: 4 ± 2%; p = 0.485; d = 0.15 ± 0.04; trivial) resulted in lower %HRmax during SSGs.

T1
Table 1.:
The distance and speed parameters calculated during different exercise to rest ratios during SSG.*†
F1
Figure 1.:
The high-speed distance (m; ≥17 km·h−1) covered during different bouts and exercise-to-rest ratios of hurling-specific SSG. Data is representative of a 4-minute SSG. Data reported as mean ± SD.
F2
Figure 2.:
The exercise intensity (%HRmax) during different bouts and exercise-to-rest ratios of hurling-specific SSG. Data is representative of a 4-minute SSG. Data reported as mean ± SD.

Discussion

The aim of the current investigation was to determine the effects of different exercise-to-rest ratios on the physical and physiological demands of hurling-specific SSGs. The main finding of the current investigation was that when smaller exercise-to-rest ratios were used as highlighted by exercise-to-rest ratios of 1:1 and 2:1, respectively, a higher physiological demand (%HRmax) in subsequent bouts of SSGs was observed, despite a significant reduction in high-speed (m; ≥17 km·h−1) and very high-speed distance (m; ≥22 km·h−1). Interestingly, total distance within all SSGs, irrespective of exercise-to-rest ratio, stayed stable between SSG bouts. Furthermore, we observed that the first bout of SSG had the lowest physiological demand (%HRmax) when compared with all other SSG bouts. Additionally, there was an observed interbout effect for work-to-rest ratios. Specifically, we observed that after 3 bouts of SSG there was a significant impact for shorter exercise-to-rest ratios (1:1, and 2:1) on high and very high-speed running performance within SSGs, with no differences observed for other exercise-to-rest ratios across all running performance variables within the first 3 bouts of SSG.

An understanding of how SSG can be adjusted is a key factor when planning training to elicit the correct training response (19). The current investigation observed that the manipulation of exercise-to-rest ratios can have an impact on the physical demands of SSG but only after the third bout of SSG. Interestingly, we observed that total distance covered during the SSG was not impacted irrespective of the exercise-to-rest ratio used. These findings may be related to a global pacing strategy employed by players during SSGs. Pacing refers to the management of onset of fatigue through the conscious and unconscious variation in exercise intensity (10), and could explain why in the present investigation a nonsignificant difference was reported for total distances covered across SSGs. Previously, Gabbett et al. (12) investigated the use of pacing strategies with semiprofessional rugby players, whereby the players altered their pacing strategy based upon the players own anticipated end point of the SSG. When players anticipated a shorter period they started quicker, and when they anticipated a longer period they started slower. As in the present investigation, the players may have employed a time-dependant anticipatory pacing strategy (29). Although the players were not informed of the specific exercise-to-rest ratio employed, it could be suggested that players anticipated a longer recovery period and, consequently, altered their physical performance accordingly. Interestingly, players had significantly reduced high-speed, very high-speed, and accelerated running performance when exercise-to-rest ratios of 2:1 and 1:1 were employed. When contrasted against 1:2 and 1:3 exercise-to-rest ratios where increases in the same physical performance variables were observed. Interestingly, any reductions in physical performance only occurred after the third bout of SSG, and only with regard to shorter exercise-to-rest ratios. The reductions in high-speed running performances can be related to reduced phosphocreatine resynthesis and removal of metabolic waste products such as lactic acid and muscle pH during the smaller work-to-rest ratios that incorporate reduced recovery periods (26,30). Indeed, pH is an important factor for the maintenance of force production during high-speed movements. Additionally, phosphocreatine availability has previously been suggested to be an important requirement for the initial phase of acceleration and high-speed actions (26,30), therefore, reductions in these physiological elements would result in reduced high-speed and accelerated movements. Coaches should be aware that short exercise-to-rest ratios (1:1 and 2:1) will reduce the physical demands of the SSG after the third bout, however, longer exercise-to-rest ratios (1:2 and 1:3) can increase the high-speed, very high-speed, and acceleration demands of SSGs.

When the percentage of HRmax was considered to differentiate across different exercise-to-rest ratios, the current study found that exercise-to-rest ratios of 2:1 (85–98% HRmax) and 1:1 (85–97% HRmax) during SSGs induced higher percentages of HRmax. Conversely, exercise-to-rest ratios of 1:2 (83–91% HRmax) and 1:3 (80–85% HRmax) resulted in lower percentages of HRmax. The above findings are in agreement with previous investigations in youth soccer that observed that reduced recovery of 1 minute between SSG bouts resulted in higher HRmax (91% HRmax) and HR reserve (88% HRres) responses in subsequent SSG bouts (16) when contrasted against longer 4-minute recovery periods (88% HRmax and 84% HRres). Data collected from 2:1, 1:1 and 1:2 exercise-to-rest ratios are in agreement with previous studies of SSGs that observed an intensity of above 90% HRmax among hurling players during SSG training (18). Exercise-to-rest ratios of 2:1 and 1:1 resulted in HRmax responses that are close to those required to improve oxygen consumption () (90–95% HRmax) (15,16). Similar to the findings of Collins et al. (6) for Gaelic football, it seems that exercise-to-rest ratios of 1:1 or 2:1 within specific SSGs are useful for improving the aerobic endurance capacity of hurling players. As a result of these data, it may be suggested that, although SSGs have been considered as valid concurrent method of training, they need to be manipulated based on the physical and physiological demands of these games. Interestingly, the first bout of SSG was observed to have the lowest physiological demand (%HRmax) of any other bout. Coaches who employ live HR monitoring should be aware that the first bout of SSG may have a lower intensity than expected because of a potential reduction in the sensitivity of HR responses to the workload completed within the specific SSG bout (1).

The current study should be considered with a number of limitations, firstly, with no technical skill data collected during these training games it is hard to gain a full appraisal as to the benefits of these games from a technical perspective. Previous investigations have shown reductions in technical performance depending on the work-to-rest ratio applied within soccer-specific SSGs (5,16,25). As a result, future studies should aim to gain an understanding as to the relationship between increased technical proficiency and exercise-to-rest ratios for hurling-specific SSGs. The application of a subject assessment of pacing within SSGs may be warranted given the observed nonsignificant reduction in total distances by players irrespective of bout number or exercise-to-rest ratio employed. The application of subjective measures could potentially be employed as a post-SSG measure to allow coaches to manipulate within-session demands to best counteract player-pacing strategies. Within hurling, SSGs are used widely by practitioners as a training methodology, therefore, the need to conduct comparative analysis on these games versus match play is needed to better understand the relative demands of these games versus match play and the required exercise-to-rest ratio needed to best replicate match play physical and physiological demands. Finally, the use of 4 Hz GPS may be considered a limitation with a degree of error associated with these units for the assessment of movement demands (3). To conclude, the current study has, for the first time, observed the effect that various exercise-to-rest ratios have on both physical and physiological demands during hurling-specific SSGs. Our study has shown that 2:1 and 1:1 exercise-to-rest ratios result in increased physiological demands within SSG. Interestingly 2:1 and 1:1 exercise-to-rest ratios also resulted in a reduction in high-speed, very high-speed, and acceleration distances within these SSGs when contrasted against 1:2 and 1:3 exercise-to-rest ratios, where these physical demand variables were increased. Coaches now have novel guidelines on how specific exercise-to-rest ratios impact the physical and physiological performance during hurling-specific SSG. Coaches now have the means to use these data to plan SSG training with regard to the specific physical and physiological requirements they wish to overload.

Practical Applications

The current investigation observed the effect that different exercise-to-rest ratios have on the physical and physiological demands during hurling-specific SSG. The aim of coaches is to overload specific areas of physical and physiological performance in isolation rather than stimulating to lesser degrees every component within the same SSG. As a consequence during field based conditioning, it is paramount that exercise-to-rest ratios within specific SSGs are fully understood, to best ensure appropriate physiological and performance adaptations. Our study observed that when smaller exercise-to-rest ratios were used as highlighted by 1:1 and 2:1exercise-to-rest ratios, respectively, a higher physiological demand (%HRmax) in subsequent bouts of SSGs was observed, despite a significant reduction in high-speed (m; ≥17 km·h−1) and very high-speed distance (m; ≥22 km·h−1). Interestingly, total distance within all SSGs irrespective of exercise-to-rest ratio stayed stable between SSG bouts. Furthermore, we observed that the first bout of SSG had the lowest physiological demand (%HRmax) when compared with all other SSG bouts. Additionally, there was an observed interbout effect for exercise-to-rest ratios. Specifically, we observed that after 3 bouts of SSG there was a significant impact for shorter exercise–to-rest ratios (1:1 and 2:1) on high-speed, very high-speed, and acceleration demands within the SSG, with no differences observed for other exercise-to-rest ratios across all physical performance variables across the first 3 bouts of SSG. Therefore, these data show that coaches can apply varying exercise-to-rest ratios during the first 3 bouts of hurling based SSG in the knowledge that there will be minimal difference in physical demands of SSGs. Within the current study, the first bout of SSG resulted in lower exercise intensity when compared with other bouts of SSGs. Coaches should be aware that when monitoring sessions with live HR telemetry that the first bout of SSG may be at a reduced intensity than observed in other bouts because of a potential reduction in the sensitivity of HR responses to the workload completed within the specific bout. Finally, the periodization of these games for hurling coaches is of paramount interest. It appears from the current data that smaller exercise-to-rest ratios (2:1; 1:1) can be used to increase the physical and physiological requirements placed on players allowing players to cover similar total distance with higher physiological demands. Longer exercise-to-rest ratios (1:2; 1:3) although resulting in reduced physiological demands can be used as games for preparation and recovery, in order to ensure players are not overexposed to high-speed distance, acceleration distance, and physiological demands before and after competitive matches. Practitioners can now use the data presented here to more accurately prescribe appropriate hurling-specific training stimuli for players during the competitive season.

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Keywords:

GPS; team sports; heart rate; training analysis; exercise ratios

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