Validation of Air Storage System for Hypoxia Exposure During Exercise

Norberto, Matheus S., João Victor G. Torini, Matheus S. Firmino, and Marcelo Papoti. Validation of air storage system for hypoxia exposure during exercise. High Alt Med Biol. 00:000-000, 2024.-Considering the importance of optimizing normobaric hypoxia exposure (i.e., higher delivery capacity), the current study aims to validate a hypoxic air storage system. The study has a cross-over, one-blind randomized design. The air storage is composed of a piping system that directs hypoxic air from a hypoxia generator into nylon bags. Sixteen men (age, 25.4 ± 4.8 years; height, 174.9 ± 9.4 cm; weight, 77.1 ± 17.2 kg) performed three incremental treadmill tests until exhaustion on different days. For test-retest, the subjects repeated two tests in similar hypoxia conditions (H1 and H2; fraction of inspired O2 [FIO2] = ∼0.13; reliability analysis), and one time in normoxia (FIO2 = ∼0.20; condition comparison). Subjects' performance, blood lactate concentration ([La-]), arterial oxygen saturation (SpO2), oxygen consumption (VO2), heart rate (HR), and several respiratory-derived variables were evaluated. A comparison was made between the rest, moderate intensity, and exhaustion stages. All variables were compared using the Friedman test with Durbin-Conover post hoc (p < 0.05). The hypoxia test-retest showed no statistical differences for any variable. Time analysis showed similar behavior for SpO2, HR, and cardiorespiratory variables (p < 0.01) for both conditions. The mean FIO2 at rest and during the incremental treadmill test was higher for normoxia (20.6 ± 0.2%) than for H1 (13.8 ± 0.8%) and H2 (13.7 ± 0.3%) (p < 0.001). The VO2 response was higher in normoxia than during hypoxia exposure at moderate intensity (Normoxia = 43.1 ± 8.1; H1 = 38.7 ± 5.7; H2 = 35.8 ± 8.8 ml.kg-1.min-1) and at the exhaustion stage (Normoxia = 52.7 ± 12.5; H1 = 41.9 ± 8.8; H2 = 40.5 ± 8.9 ml.kg-1.min-1) (p < 0.01). SpO2 and HR showed excellent intraclass correlation coefficient (ICC) during all moments, whereas VO2, SpO2, ratio between ventilation and CO2 production (VE/VCO2), ratio between oxygen consumption and ventilation (VE/VO2), and HR showed moderate or good ICC and coefficient of variation <9% during hypoxia test-retest exercises. Thus, the air storage system showed validity for its application and reliability in the measurements associated.

Artificial Turf Increases the Physical Demand of Soccer by Heightening Match Running Performance Compared with Natural Grass

ABSTRACT

Modric, T, Esco, M, Perkovic, S, Basic, Z, Versic, S, Morgans, R, and Sekulic, D. Artificial turf increases the physical demand of soccer by heightening match running performance compared with natural grass. J Strength Cond Res 37(11): 2222-2228, 2023-This study aimed to determine differences in match running performance (MRP) of elite soccer players (n = 31) during matches played on artificial turf (AT) and natural grass (NG). The players' MRP (AT; 131 observations, NG; 135 observations) were collected during official matches (n = 32) using global positioning system and classified according to their playing positions as central defenders, central midfielders, fullbacks, forwards, and wingers. The MRP variables included total distance covered (TD), low-intensity running (LIR), moderate-intensity running (MIR), high-intensity running (HIR), total (Tacc) and high-intensity accelerations (Hacc), and total (Tdec) and high-intensity decelerations (Hdec). The influence of match outcome, location, and opponent quality was controlled for as contextual factors. Playing matches on AT resulted in (a) increased TD (Cohen's d (d) = 0.55, 0.61, and 0.28, respectively), MIR (d = 0.91, 0.79, and 0.49, respectively), and HIR (d = 0.67, 0.44, and 0.38, respectively) for central defenders, central midfielders, fullbacks; (b) increased Tacc (d = 0.38, 0.37, and 0.4, respectively) and Tdec (d = 0.31, 0.34, and 0.31, respectively) for central defenders, central midfielders, and wingers; and (c) decreased Hdec (d = -1.5) for forwards. These results show that playing on AT is more physically demanding for defensive and midfield players than playing on NG. Soccer coaches should consider implementing preparatory strategies that mitigate the increased demands of playing on AT for these players, especially before a competitive period when transitions between pitch surfaces routinely occur.

Inter-muscular coordination during running on grass, concrete and treadmill

Running is an exercise that can be performed in different environments that imposes distinct foot-floor interactions. For instance, running on grass may help reducing instantaneous vertical impact loading, while compromising natural speed. Inter-muscular coordination during running is an important factor to understand motor performance, but little is known regarding the impact of running surface hardness on inter-muscular coordination. Therefore, we investigated whether inter-muscular coordination during running is influenced by running surface. Surface electromyography (EMG) from 12 lower limb muscles were recorded from young male individuals (n = 9) while running on grass, concrete, and on a treadmill. Motor modules consisting of weighting coefficients and activation signals were extracted from the multi-muscle EMG datasets representing 50 consecutive running cycles using non-negative matrix factorization. We found that four motor modules were sufficient to represent the EMG from all running surfaces. The inter-subject similarity across muscle weightings was the lowest for running on grass (r = 0.76 ± 0.11) compared to concrete (r = 0.81 ± 0.07) and treadmill (r = 0.78 ± 0.05), but no differences in weighting coefficients were found when analyzing the number of significantly active muscles and residual muscle weightings (p > 0.05). Statistical parametric mapping showed no temporal differences between activation signals across running surfaces (p > 0.05). However, the activation duration (% time above 15% peak activation) was significantly shorter for treadmill running compared to grass and concrete (p < 0.05). These results suggest predominantly similar neuromuscular strategies to control multiple muscles across different running surfaces. However, individual adjustments in inter-muscular coordination are required when coping with softer surfaces or the treadmill's moving belt.

Comparison of physiological responses of running on a nonmotorized and conventional motor-propelled treadmill at similar intensities

This study aimed to test the agreement of the incremental test's physiological responses between tethered running on a nonmotorized treadmill (NMT) to matched relative intensities while running on a conventional motorized treadmill (MT). Using a within-subject crossover design, nine male recreational runners (age = 22 ± 5 years; height = 175 ± 6 cm; weight = 68.0 ± 16.6 kg) underwent two test sessions: one was an incremental intensity protocol on an MT; the other was on an instrumented NMT. Intensity thresholds at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text V}}$$\end{document}V˙O_2max, respiratory compensation point (iRCP), and lactate threshold (iLT) were registered for analysis, together with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text V}}$$\end{document}V˙˙O₂, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text V}}$$\end{document}V˙˙E, ƒ_R, and blood lactate concentration ([Lac]). Comparisons were based on hypothesis testing (Student's T-test), effect sizes (Cohen's d), ICC, and Bland Altman analysis. Statistical significance was accepted at p < 0.05. Attained \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text V}}$$\end{document}V˙O_2max (MT = 52.2 ± 7.3 mL·kg^-1·min^-1 vs NMT = 50.1 ± 8.1 mL·kg^-1·min^-1) and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text V}}$$\end{document}V˙˙O₂ at iRCP (MT = 46.3 ± 7.2 mL·kg^-1·min^-1 vs NMT = 42.8 ± 9.3 mL·kg^-1·min^-1) were not different between ergometers (p = 0.15 and 0.13, respectively), with significant ICCs (0.84 and 0.70, respectively) and Pearson’s correlations (r = 0.87 and 0.76, respectively). The [Lac] at iLT presented poor agreement between conditions. Significant correlations were found (r between 0.72 and 0.83) for relative power values of i\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text V}}$$\end{document}V˙O_2max (6.56 ± 1.28 W·kg⁻¹), iRCP (4.38 ± 1.50 W·kg⁻¹), and iLT (4.15 ± 1.29 W·kg⁻¹) related to their counterpart obtained on MT. Results show that running on an NMT offers a higher glycolytic demand under the same relative internal load as running on an MT but with a similar aerobic response and correlated intensity determination.

Influence of the artificial turf certification on physical performance and muscle damage in football players (QUALTURF PROJECT)

This study aimed to analyse the influence of the FIFA Quality PRO certification of artificial turf pitches on the physical, physiological performance and muscle damage in soccer players. Fifteen healthy male players (21.2 ± 1.4 years; 178.2 ± 4.3 cm; 79.1 ± 8.3 kg) from a university football team were selected to participate in the research. Mechanical properties related to surface-player interaction were assessed on the two surfaces selected for this study. A randomized design was used and the players performed the Ball-sport Endurance and Sprint Test (BEAST90) on the different artificial turf fields. Average time of the 20 m sprints was longer on the FIFA Quality Pro surface than on the non-certified pitch (+ 0.13 s; p < 0.05; CI 95% - 0.01 to 0.27; ES: 0.305). The players' perceived effort was higher in the first (+ 2.64; p < 0.05; CI 95% 0.92 to 4.35; ES: 1.421) and the second half (+ 1.35; p < 0.05; CI 95% - 0.02 to 2.72; ES: 0.637) of the test on the FIFA Quality Pro field. Comparative analysis between surfaces showed no significant differences in the time spent in each of the heart rate zones and higher concentrations of CK (+ 196.58; p > 0.05; CI 95% 66.54 to 326.61; ES: 1.645) were evidenced in the non-certified pitch surface. In response to a simulated match protocol, markers of post-exercise muscle damage may be reduced on accredited artificial turf fields. These insights can provide the opportunity to maximize the efficiency of training sessions and reduce the risk of injury during the season.

Effect of Natural Turf, Artificial Turf, and Sand Surfaces on Sprint Performance. A Systematic Review and Meta-Analysis

The aim of this study was to analyze the influence of natural turf, artificial turf, and sand on sprint performance in different sports and to determine how the sport surface affects sprint performance. A systematic search was conducted in Pubmed, Web of Sciences, and SPORTDiscus databases. Out of 5644 studies, 11 studies were included in the meta-analysis. The studies were very heterogeneous, as they examined different structural characteristics or quality parameters. The studies on natural turf and sand showed significant improvements on sprint speed during training. On the other hand, the analysis of fatigue did not reveal significant differences in the deterioration of sprint speed on both natural and artificial turf. Significance was set at p < 0.05. In conclusion, although lower performance in sprint was reported on sand, further studies are needed to explain the differences in sprint on natural and artificial turf.

The Influence of Playing Surface on the Loading Response to Soccer-Specific Activity

CONTEXT

The influence of playing surface on injury risk in soccer is contentious, and contemporary technologies permit an in vivo assessment of mechanical loading on the player.

OBJECTIVE

To quantify the influence of playing surface on the PlayerLoad elicited during soccer-specific activity.

DESIGN

Repeated measures, field-based design.

SETTING

Regulation soccer pitches.

PARTICIPANTS

Fifteen amateur soccer players (22.1 [2.4] y), injury free with ≥6 years competitive experience.

INTERVENTIONS

Each player completed randomized order trials of a soccer-specific field test on natural turf, astroturf, and third-generation artificial turf. GPS units were located at C7 and the mid-tibia of each leg to measure triaxial acceleration (100 Hz).

MAIN OUTCOME MEASURES

Total accumulated PlayerLoad in each movement plane was calculated for each trial. Ratings of perceived exertion and visual analog scales assessing lower-limb muscle soreness were measured as markers of fatigue.

RESULTS

Analysis of variance revealed no significant main effect for playing surface on total PlayerLoad (P = .55), distance covered (P = .75), or postexercise measures of ratings of perceived exertion (P = .98) and visual analog scales (P = .61). There was a significant main effect for GPS location (P < .001), with lower total loading elicited at C7 than mid-tibia (P < .001), but with no difference between limbs (P = .70). There was no unit placement × surface interaction (P = .98). There was also a significant main effect for GPS location on the relative planar contributions to loading (P < .001). Relative planar contributions to loading in the anterioposterior:mediolateral:vertical planes was 25:27:48 at C7 and 34:32:34 at mid-tibia.

CONCLUSIONS

PlayerLoad metrics suggest that playing surface does not influence mechanical loading during soccer-specific activity (not including tackling). Clinical reasoning should consider that PlayerLoad magnitude and axial contributions were sensitive to unit placement, highlighting opportunities in the objective monitoring of load during rehabilitation.

Mechanical Properties of Treadmill Surfaces Compared to Other Overground Sport Surfaces

The mechanical properties of the surfaces used for exercising can affect sports performance and injury risk. However, the mechanical properties of treadmill surfaces remain largely unknown. The aim of this study was, therefore, to assess the shock absorption (SA), vertical deformation (VD) and energy restitution (ER) of different treadmill models and to compare them with those of other sport surfaces. A total of 77 treadmills, 30 artificial turf pitches and 30 athletics tracks were assessed using an advanced artificial athlete device. Differences in the mechanical properties between the surfaces and treadmill models were evaluated using a repeated-measures ANOVA. The treadmills were found to exhibit the highest SA of all the surfaces (64.2 ± 2; p < 0.01; effect size (ES) = 0.96), while their VD (7.6 ± 1.3; p < 0.01; ES = 0.87) and ER (45 ± 11; p < 0.01; ES = 0.51) were between the VDs of the artificial turf and track. The SA (p < 0.01; ES = 0.69), VD (p < 0.01; ES = 0.90) and ER (p < 0.01; ES = 0.89) were also shown to differ between treadmill models. The differences between the treadmills commonly used in fitness centers were much lower than differences between the treadmills and track surfaces, but they were sometimes larger than the differences with artificial turf. The treadmills used in clinical practice and research were shown to exhibit widely varying mechanical properties. The results of this study demonstrate that the mechanical properties (SA, VD and ER) of treadmill surfaces differ significantly from those of overground sport surfaces such as artificial turf and athletics track surfaces but also asphalt or concrete. These different mechanical properties of treadmills may affect treadmill running performance, injury risk and the generalizability of research performed on treadmills to overground locomotion.

A Comparison of Incremental Running Field and Treadmill Tests in Young Soccer Players

The purpose of this study was to compare the incremental running tests performed by young soccer players on a treadmill (Tr) and in the field (FT_cod: 100 m change of direction and FT_cir: 100 m circle). Nineteen players (average age 17.4 ± 1.1 years; body height 172.0 ± 5.7 cm; body mass 68.9 ± 6.7 kg) volunteered to perform incremental Tr , FT_cod and FT_cir running tests. In all three tests, players ran for 3 min at 8, 10, 12 and 14 km∙h^-1 and were given a 1 min rest interval between subsequent stages. Blood lactate concentrations (La^-) were measured at 1 min rest intervals and the heart rate (HR) responses of players were recorded during the tests. After a 5 min recovery period, the second part of the test started; players ran at 15 km∙h^-1 with velocity increments of 1 km∙h^-1 every 1 min until exhaustion. This part was performed to determine maximum HR, maximum La^- and the players’ final velocities. The results showed that players had significantly lower La^- (F = 6.93, p = 0.07, η² = 0.46, 95%CI_(TR-FTcir) = -1.91/-0.34, 95%CI_(TR-FTcod) = -1.59/-0.05) and HR (F = 9.08, p = 0.02, η² = 0.53, 95%CI_(TR-FTcir) = -6.98/-1.68, 95%CI_(TR-FTcod) = -7.19/1.08) responses in the Tr test than in the FT_cir and FT_cod tests at 14 km∙h^-1. It was also found that players completed the Tr test (F = 58.22, p = 0.00, η² = 0.87) at higher final running velocities than the FT_cir (95%CI_(TR-FTcir) = 1.67/2.78) and FT_cod (95%CI_(TR-FTcod) = 1.69/2.85) tests. In conclusion, when coaches or sports scientists plan to train at higher running velocities or according to the final velocity in the test, it is advisable to carry out testing in the circumstances under which training will be carried out (in the field or on a treadmill).

A Proposed Method to Assess the Mechanical Properties of Treadmill Surfaces

The aim of this study was to define a reliable and sensitive test method for assessing Shock Absorption (SA), Vertical Deformation (VD), and Energy Restitution (ER) in treadmill surfaces. A total of 42 treadmills belonging to four different models were included in the study: (a) Technogym Jog700 Excite (n = 10), (b) Technogym Artis Run (n = 12), (c) LifeFitness Integrity Series 97T (n = 11), and (d) LifeFitness Integrity Series DX (n = 9). An advanced artificial athlete (AAA) device was used to assess SA, VD, and ER at three different locations along the longitudinal axis of each treadmill and in the support area of the athletes’ feet. For each location, our results show that the error assumed when performing one impact with the AAA instead of three (SA ≤ |0.1|%, VD ≤ |0.0| mm, and ER ≤ |0.2|%) is lower than the smallest changes that can be detected by the measuring device (SA = 0.4%, VD = 0.2 mm, and ER = 0.9%). Also, our results show the ability of the test method to detect meaningful differences between locations once the one-impact criterium is adopted, since absolute minimum differences between zones (SA: |0.6|%, VD: |0.3| mm, and ER: |1.2|%) were above the uncertainty of the measuring device. Therefore, performing a single impact with the AAA in each of the three locations described in this study can be considered a representative and reliable method for assessing SA, VD, and ER in treadmill surfaces.

Mechanical Properties of Treadmill Surfaces and Their Effects on Endurance Running

PURPOSE

To characterize, for the first time, the mechanical properties of treadmill surfaces along with a practical interpretation of their influence on physiological and perceived demands during endurance running compared with other widely used surfaces such as asphalt and tartan tracks.

METHODS

Ten experienced male endurance runners performed a 40-minute running bout at a preferred constant speed on 3 different surfaces (after a randomized, counterbalanced order with a 7-d interval between trials): asphalt, tartan, or treadmill. Shock absorption, vertical deformation, and energy restitution were measured for the 3 surfaces. Intensity (based on heart rate data) and rating of perceived exertion were monitored.

RESULTS

The values of shock absorption averaged 0.0% (asphalt), 37.4% (tartan), and 71.3% (treadmill), while those of vertical deformation and energy restitution averaged 0.3, 2.2, and 6.5 mm and 90.8%, 62.6%, and 37.0%, respectively. Running intensity (as determined by heart rate data) was higher overall on the treadmill than tartan but not asphalt running. Except for the first 10 minutes, all mean rating of perceived exertion values were significantly higher in asphalt and treadmill than in tartan. No significant differences were identified between treadmill and asphalt.

CONCLUSIONS

The considerably higher shock absorption of the treadmill than the tartan surface leads to a reduction in the amount of energy returned to the athlete, which in turn increases physiological stress and rating of perceived exertion during endurance running.

The Influence of Soccer Playing Surface on the Loading Response to Ankle (P)Rehabilitation Exercises

CONTEXT

Contemporary synthetic playing surfaces have been associated with an increased risk of ankle injury in the various types of football. Triaxial accelerometers facilitate in vivo assessment of planar mechanical loading on the player.

OBJECTIVE

To quantify the influence of playing surface on the PlayerLoad elicited during footwork and plyometric drills focused on the mechanism of ankle injury.

DESIGN

Repeated-measures, field-based design.

SETTING

Regulation soccer pitches.

PARTICIPANTS

A total of 15 amateur soccer players (22.1 [2.4] y), injury free with ≥6 years competitive experience.

INTERVENTIONS

Each player completed a test battery comprising 3 footwork drills (anterior, lateral, and diagonal) and 4 plyometric drills (anterior hop, inversion hop, eversion hop, and diagonal hop) on natural turf (NT), third-generation artificial turf (3G), and AstroTurf. Global positioning system sensors were located at C7 and the mid-tibia of each leg to measure triaxial acceleration (100 Hz).

MAIN OUTCOME MEASURES

PlayerLoad in each axial plane was calculated for each drill on each surface and at each global positioning system location.

RESULTS

Analysis of variance revealed a significant main effect for sensor location in all drills, with PlayerLoad higher at mid-tibia than at C7 in all movement planes. AstroTurf elicited significantly higher PlayerLoad in the mediolateral and anteroposterior planes, with typically no difference between NT and 3G. In isolated inversion and eversion hopping trials, the 3G surface also elicited lower PlayerLoad than NT.

CONCLUSIONS

PlayerLoad magnitude was sensitive to unit placement, advocating measurement with greater anatomical relevance when using microelectromechanical systems technology to monitor training or rehabilitation load. AstroTurf elicited higher PlayerLoad across all planes and drills and should be avoided for rehabilitative purposes, whereas 3G elicited a similar mechanical response to NT.

Differences in motivation during the bench press movement with progressive loads using EEG analysis

Considering our preliminary research with EEG analysis of the bench press in experienced powerlifters, we hypothesized that there would be significant differences in motivation between novice and elite powerlifters. Therefore the main objective of this study was to identify patterns of frontal alpha asymmetry (FAA) of the prime movers by alpha frequency band analysis (named as alpha motivation values) for each 35–100% one-repetition maximum (1RM) during the flat bench press. Ten novice powerlifters with no more than 2.5 years of resistance training experience and ten elite powerlifters with at least 7.5 years of training experience participated in the study. All participants were required to squat, bench press, and deadlift 100, 125, and 150% of their body mass, respectively. The athletes constituted a homogeneous group with respect to age (mean 22.3 ± 0.5 years). The EEG recordings were conducted using automatic headcups with 19 electrodes that were placed according to the International 10-20 Electrode Placement System. Signals from 8–12 Hz considering points F3 and F4 were analyzed. Furthermore, electromyographic (EMG) signals from the trapezius muscle were recorded. Before testing, moods and emotions of subjects were assessed to eliminate subjects with intense emotions. The results showed brain activity before, during and after cognitive and motor performance using electroencephalography (EEG). However, considering the still existing problems of movement artefacts during EEG measurements, eligible sports and exercises are limited to those that are relatively motionless during execution. Further studies are needed to confirm these preliminary results.

Effects of Playing Surface on Physical, Physiological, and Perceptual Responses to a Repeated-Sprint Ability Test: Natural Grass Versus Artificial Turf

PURPOSE

The effect of playing surface on physical performance during a repeated-sprint ability (RSA) test and the mechanisms for any potential playing-surface-dependent effects on RSA performance are equivocal. The purpose of this study was to investigate the effect of natural grass (NG) and artificial turf (AT) on physical performance, ratings of perceived exertion, feeling scale, and blood biomarkers related to anaerobic contribution (blood lactate [Lac]), muscle damage (creatine kinase and lactate dehydrogenase), inflammation (C-reactive protein), and immune function (neutrophils [NEU], lymphocytes [LYM], and monocytes) in response to an RSA test.

METHODS

A total of 9 male professional football players from the same regional team completed 2 sessions of RSA testing (6 × 30 s interspersed with a 35-s recovery) on NG and AT in a randomized order. During the RSA test, total (sum of distances) and peak (highest distance covered in a single repetition) distance covered were determined using a measuring tape, and the decrement in sprinting performance from the first to the last repetition was calculated. Before and after the RSA test, ratings of perceived exertion, feeling scale, and Lac, creatine kinase, lactate dehydrogenase, C-reactive protein, NEU, LYM, and monocytes were recorded in both NG and AT conditions.

RESULTS

Although physical performance declined during the RSA blocks on both surfaces (P = .001), the distance covered declined more on NG (15%) than on AT (11%; P = .04; effect size [ES] = -0.34; 95% confidence interval [CI], -1.21 to 0.56) with a higher total distance covered (+6% [2%]) on AT (P = .018; ES = 1.15; 95% CI, 0.16 to 2.04). In addition, lower ratings of perceived exertion (P = .04; ES = -0.49; 95% CI, -1.36 to 0.42), Lac, NEU, and LYM (P = .03; ES = -0.80; 95% CI, -1.67 to 0.14; ES = -0.16; 95% CI, -1.03 to 0.72; and ES = -0.94; 95% CI, -1.82 to 0.02, respectively) and more positive feelings (P = .02; ES = 0.81; 95% CI, -0.13 to 1.69) were observed after the RSA test performed on AT than on NG. No differences were observed in the remaining physical and blood markers.

CONCLUSION

These findings suggest that RSA performance is enhanced on AT compared with NG. This effect was accompanied by lower fatigue perception and Lac, NEU, and LYM and a more pleasurable feeling. These observations might have implications for physical performance in intermittent team-sport athletes who train and compete on different playing surfaces.

The Influence of Sport-Field Properties on Muscle-Recruitment Patterns and Metabolic Response

PURPOSE

To investigate different sport-field properties' influence on muscle-recruitment patterns and metabolic response during a series of running and agility drills.

METHODS

Eleven male athletes were fitted with a standard multipurpose training shoe. The test protocol consisting of 4 high-intensity trials with 60-s rests between trials performed on 2 fields with different properties. Time-dependent field properties were measured using the American Standards for Testing and Materials protocol (F-1936). A 30-m pretest and posttest sprint determined fatigue and player performance. Electromyography (EMG) recorded muscle activity for vastus medialis, biceps femoris, gastrocnemius medial head, and tibialis anterior, and metabolic activity analyzed maximal oxygen consumption, heart rate, respiratory exchange ratio, metabolic equivalent, and energy expenditure.

RESULTS

A difference was calculated for muscle activity across trials (P = .01) for both surfaces. Muscle activity was <13% on the field with less energy return (P = .01). Metabolic components (maximal oxygen consumption, heart rate, respiratory exchange ratio, metabolic equivalent, and energy expenditure) were significantly different across trials (P = .01) but not significantly different between fields. The participants completed the agility course (5.2%) faster on the field with greater energy return, while caloric expenditure was similar between fields.

CONCLUSIONS

The findings indicate that field mechanical properties influence muscle-activation patterns. The field demonstrating the greatest magnitude of energy return produces the lowest sprint and agility course times; however, performing on a field exhibiting unfamiliar mechanical properties could cause the athlete to produce atypical movement patterns that might contribute to overuse of the neuromuscular system.

Contextual factors on physical demands in professional women's soccer: Female Athletes in Motion study

The aim of this study was to examine the impact of contextual factors on relative locomotor and metabolic power distances during professional female soccer matches. Twenty-eight players (forwards, n = 4; midfielders, n = 12; defenders, n = 12) that competed in a 90-min home and away match (regular season only). The generalised estimating equations (GEE) was used to evaluate relative locomotor and metabolic power distances for three contextual factors: location (home vs. away), type of turf (natural vs. artificial), and match outcome (win, loss and draw). No differences were observed for home vs. away matches. Moderate-intensity running (20.0 ± 1.0 m min^-1 and 16.4 ± 0.9 m min^-1), high-intensity running (8.6 ± 0.4 m min^-1 and 7.3 ± 0.4 m min^-1) and high-metabolic power (16.3 ± 0.5 m min^-1 and 14.4 ± 0.5 m min^-1) distances were elevated on artificial turf compared to natural grass, respectively. Relative sprint distance was greater during losses compared with draws (4.3 ± 0.4 m min^-1 and 3.4 ± 0.3 m min^-1). Overall physical demands of professional women's soccer were not impacted by match location. However, the elevation of moderate and high-intensity demands while playing on artificial turf may have implications on match preparations as well as recovery strategies.

Physiological and Physical Responses According to the Game Surface in a Soccer Simulation Protocol

PURPOSE

Recent studies have shown that soccer players' responses are similar on natural grass (NG) and artificial turf (AT), but they did not control the mechanical properties of these surfaces. This work aimed to analyze the influence of the game surface on amateur soccer players' physical and physiological responses using a soccer simulation protocol.

METHODS

A total of 16 amateur players performed 3 bouts of the soccer simulation protocol on AT, and, on another day, 3 bouts on NG. The mechanical properties of both surfaces were recorded. The order of surfaces was randomly established for each participant. Physiological responses of players were assessed before and after the 6-repeated-sprints test existing at the midpoint of each bout. Fatigue (% best; % diff) and general variables (total time; best time, mean time; maximum speed) for both the repeated sprint test (RST) and the agility tests (nonlinear actions at maximum speed) incorporated into the soccer simulation protocol were also analyzed.

RESULTS

The 2 surfaces displayed different mechanical properties. Physical responses were found similar for both surfaces (P > .05) before and after the RST. There were no surface differences in sprint times or fatigue variables for the RST (P > .05). The agility test was faster on AT than on NG in bout 1 (average speed [+1.17 km/h;P = .037]; agility test cut time [-0.31 s; P = .027] and best time [-0.52 s; P = .042]).

CONCLUSIONS

The differences in the mechanical properties of the 2 surfaces are not sufficient to cause differences in the physiological and physical responses of soccer players, although they may affect turns and cuts.

Switching between pitch surfaces: practical applications and future perspectives for soccer training

INTRODUCTION

Soccer training and completion is conventionally practiced on natural grass (NG) or artificial turf (AT). Recently, AT pitches for training/competition, and of unstable surfaces for injury prevention training has increased. Therefore, soccer players are frequently exposed to variations in pitch surface during either training or competition. These ground changes may impact physical and physiological responses, adaptations as well as the injury. The aim of this review was to summarize the acute physical and physiological responses, chronic adaptations, and injury risk associated with exercising on different pitch surfaces in soccer.

EVIDENCE ACQUISITION

Eligible studies were published in English, had pitch surface as an independent variable, and had physical, physiological or epidemiological information as outcome variables. Specific data extracted from the articles included the training response, training adaptations or injury outcomes according to different pitch surfaces. A total of 224 studies were retrieved from a literature search.

EVIDENCE SYNTHESIS

Twenty articles met the inclusion criteria: 9 for acute physical and physiological responses, 2 for training adaptations and 9 for injury assessment. The literature lacks consistent evidence regarding the effects of pitch surface on performance and health outcomes in soccer players. However, it seems that occasionally switching training surfaces seems a valuable strategy for focusing on specific musculoskeletal queries and enhancing players' fitness. For instance, sand training may be occasionally proposed as complementary training strategy, given the recruitment of additional musculature probably not involved on firmer surfaces, but the possible training-induced adaptations of non-conventional soccer surfaces (e.g., sand) might potentially result into a negative transfer on AT or NG.

CONCLUSIONS

Since the specific physical demands of soccer can differ between surfaces, coaches should resort to the use of non-traditional surfaces with parsimony, emphasizing the specific surface-related motor tasks, normally observed on natural grass or artificial turf. Further studies are required to better understand the physiological effects induced by systematic surface-specific training, or switching between pitch surfaces.

Effects of Bout Duration on Players’ Internal and External Loads During Small-Sided Games in Young Soccer Players

Purpose: To investigate the effects of different bout durations on internal and external loads of young soccer players during different small-sided games (SSGs). Methods: Fifteen young male soccer players (average age 17 ± 1 y) participated in 2 vs 2, 3 vs 3, and 4 vs 4 SSGs. All games lasted 12 min playing time in total, but each SSG format further consisted of 4 bout durations: continuous (CON: 1 bout × 12 min) or interval with short (SBD: 6 bouts  × 2 min), medium (MBD: 3 bouts × 4 min), or long (LBD: 2 bouts × 6 min) bout durations. During the SSGs, heart-rate (HR) responses and distance covered in different speed zones (walking and low-intensity, moderate-intensity, and high-intensity running) were measured. Rating of perceived exertion (RPE) and blood lactate (La−) were determined at the end of each SSG. Results: The SBD format elicited significantly lower %HRmax responses compared to LBD and CON in all formats (P < .05). The SBD format also showed significantly shorter distances covered in walking and greater distances covered in moderate-intensity running, as well as significantly greater total distance covered compared to LBD and CON in all formats (P < .05). In addition, LBD produced significantly lower La− and RPE responses than SBD and CON in all formats (P < .05). Conclusions: These results suggest that coaches and sport scientists who want to achieve higher internal loads could use SBD and CON timing protocols, while those who want to achieve higher external loads might prefer to use SBD and MBD when planning all SSG formats.

Neuromuscular responses and physiological patterns during a soccer simulation protocol. Artificial turf versus natural grass

BACKGROUND

Latest studies suggest similar performance of soccer players either on artificial turf (AT) or natural grass (NG). However, it is not clear if their muscular and physiological responses are also similar on both surfaces. This research aims to assess the influence of game surface on physiological patterns and neuromuscular responses of soccer players during a soccer simulation protocol (SSP) that incorporates repeated sprints and nonlinear actions at maximum speed.

METHODS

Sixteen amateur soccer players completed three bouts of the SSP on both AT and NG. The mechanical behaviour of both surfaces was recorded and the order was randomly established for each player. The physiological responses were measured during the SSP. A contra-movement jump and a tensiomyography analysis of the rectus femoris (RF) and biceps femoris (BF) were assessed right before and right after the SSP.

RESULTS

Both surfaces presented different mechanical properties. No differences among either surfaces or bouts were found for heart rate (HR) peak and HR mean (P>0.05). While the half-relaxation time of the RF on NG decreased after the SSP (right-leg: -44.430 ms; P=0.049; left-leg: -52.131 ms; P=0.008), the sustain time of the BF decreased after the SSP on AT (right-leg: +64.868 ms; P=0.007; left-leg: +87.564 ms; P<0.001). No differences between surfaces were found for the contra-movement jump.

CONCLUSIONS

The mechanical behaviour of both surfaces does not differ enough to cause different physiological and neuromuscular responses. Playing on AT should cause similar neuromuscular responses to NG.

Effects of structural components of artificial turf on the transmission of impacts in football players

The third generation of artificial turf systems (ATS) has matched the mechanical behaviour of natural grass, but today a high heterogeneity at structural level and mechanical behaviour in the new ATS also exists. The objective was to analyse the effect of the structural components of ATS football pitches and running speed on the capacity of impact attenuation. A total of 12 athletes were evaluated at three speed conditions (3.33 m/s, 4 m/s and maximum speed) on four different ATS, classifying them by their components (length of fibre, type of in-fill and sub-base). Impact attenuation was significantly higher in ATS3, characterised by longer fibre compared to other ATS with less fibre length. The ATS4 with a higher length fibre and built on compacted granular material proportioned significantly lower values in the maximum peaks of tibia acceleration. Finally, as speed increases, the peak tibia impacts were significantly higher. Longer fibre length and the capacity to accommodate a higher quantity of infill facilitate higher impact attenuation. Equally, a compacted granular sub-base is related to lower magnitude of maximum tibia peaks. Finally, the magnitude of the tibia acceleration peaks is dependent of running speed for all ATS analysed, being higher as speed increases.

Physical and Physiological Responses of Amateur Football Players on Third-Generation Artificial Turf Systems During Simulated Game Situations

Sánchez-Sánchez, J, García-Unanue, J, Felipe, JL, Jiménez-Reyes, P, Viejo-Romero, D, Gómez-López, M, Hernando, E, Burillo, P, and Gallardo, L. Physical and physiological responses of amateur football players on third generation artificial turf systems during simulated game situations. J Strength Cond Res 30(11): 3165-3177, 2016-The aim of this study is to evaluate the physical and physiological load imposed on amateur football players in a simulated game situation on different artificial turf systems. For that purpose, 20 football players (21.65 ± 3.10 year old) were monitored with Global Positioning Systems and heart rate bands during 45-minutes games on 4 selected artificial turf systems. The results show more covered distance in high-intensity ranges on the system with lower levels of damping and higher rates of rotational traction (p ≤ 0.05). Likewise, this system of artificial turf demonstrated a high number of sprints (12.65 ± 5.67) and more elevated maximum speed peaks during the last part of the game (28.16 ± 2.90 km·h) in contrast to the systems with better damping capacity (p ≤ 0.05). On the other hand, the physiological load was similar across the 4 artificial turf systems (p > 0.05). Finally, the regression analysis demonstrated a significant influence of the mechanical properties of the surface on global distance (15.4%), number (12.6%), and maximum speed (16.6%) of the sprints. To conclude, the mechanical variability of the artificial turf systems resulted in differences in the activity profiles and the players' perceptions during simulated football games.

The Hoff circuit test is more specific than an incremental treadmill test to assess endurance with the ball in youth soccer players

The assessment of aerobic endurance is important for training prescription in soccer, and is usually measured by straight running without the ball on a track or treadmill. Due to the ball control and technical demands during a specific soccer test, the running speeds are likely to be lower compared to a continuous incremental test. The aim of the present study was to compare the heart rate (HR), rating of perceived exertion (RPE) and speeds corresponding to 2.0 mmol∙L^-1, 3.5 mmol∙L^-1, lactate threshold (Dmax method) and peak lactate determined in the laboratory and in the Hoff circuit soccer-specific test. Sixteen soccer players (16±1 years) underwent two incremental tests (laboratory and Hoff circuit tests). The speeds were significantly higher in the treadmill test than on the Hoff circuit (2.0 mmol∙L^-1: 9.5±1.2 and 8.1±1.0 km∙h^-1; 3.5 mmol∙L^-1: 12.0±1.2 and 10.2±1.1 km∙h^-1; Dmax: 11.4±1.4 and 9.3±0.4 km∙h^-1; peak lactate: 14.9±1.6 and 10.9±0.8 km∙h^-1). The HR corresponding to 3.5 mmol∙L-1 was significantly higher on the Hoff circuit compared to the laboratory test (187.5±18.0 and 178.2±17.6 bpm, respectively; P <0.001), while the RPE at the last incremental stage was lower on the Hoff circuit (P < 0.01). The speeds during the Hoff specific soccer test and the HR corresponding to 2.0 mmol∙L^-1, 3.5 mmol∙L^-1 and Dmax/threshold were different compared with the laboratory test. The present study shows that it is possible to assess submaximal endurance related variables specifically in soccer players.

Influence of the mechanical properties of third-generation artificial turf systems on soccer players' physiological and physical performance and their perceptions

The aim of this research was to evaluate the influence of the mechanical properties of artificial turf systems on soccer players' performance. A battery of perceptive physiological and physical tests were developed on four different structural systems of artificial turf (System 1: Compacted gravel sub-base without elastic layer; System 2: Compacted gravel sub-base with elastic layer; System 3: Asphalt sub-base without elastic layer; System 4: Asphalt sub-base with elastic layer). The sample was composed of 18 soccer players (22.44±1.72 years) who typically train and compete on artificial turf. The artificial turf system with less rotational traction (S3) showed higher total time in the Repeated Sprint Ability test in comparison to the systems with intermediate values (49.46±1.75 s vs 47.55±1.82 s (S1) and 47.85±1.59 s (S2); p<0.001). The performance in jumping tests (countermovement jump and squat jump) and ball kicking to goal decreased after the RSA test in all surfaces assessed (p<0.05), since the artificial turf system did not affect performance deterioration (p>0.05). The physiological load was similar in all four artificial turf systems. However, players felt more comfortable on the harder and more rigid system (S4; visual analogue scale = 70.83±14.28) than on the softer artificial turf system (S2; visual analogue scale = 54.24±19.63). The lineal regression analysis revealed a significant influence of the mechanical properties of the surface of 16.5%, 15.8% and 7.1% on the mean time of the sprint, the best sprint time and the maximum mean speed in the RSA test respectively. Results suggest a mechanical heterogeneity between the systems of artificial turf which generate differences in the physical performance and in the soccer players' perceptions.

The perceptions of professional soccer players on the risk of injury from competition and training on natural grass and 3rd generation artificial turf

BACKGROUND

The purpose of this study was to describe professional soccer players' perceptions towards injuries, physical recovery and the effect of surface related factors on injury resulting from soccer participation on 3rd generation artificial turf (FT) compared to natural grass (NG).

METHODS

Information was collected through a questionnaire that was completed by 99 professional soccer players from 6 teams competing in Major League Soccer (MLS) during the 2011 season.

RESULTS

The majority (93% and 95%) of the players reported that playing surface type and quality influenced the risk of sustaining an injury. Players believed that playing and training on FT increased the risk of sustaining a non-contact injury as opposed to a contact injury. The players identified three surface related risk factors on FT, which they related to injuries and greater recovery times: 1) Greater surface stiffness 2) Greater surface friction 3) Larger metabolic cost to playing on artificial grounds. Overall, 94% of the players chose FT as the surface most likely to increase the risk of sustaining an injury.

CONCLUSIONS

Players believe that the risk of injury differs according to surface type, and that FT is associated with an increased risk of non-contact injury. Future studies should be designed prospectively to systematically track the perceptions of groups of professional players training and competing on FT and NG.

A Meta-Analysis of Soccer Injuries on Artificial Turf and Natural Grass

The goal of this investigation was to determine if playing or training on third-generation artificial turf (AT) surfaces increases the incidence rate of injuries compared to natural grass (NG) surfaces. This was accomplished by a meta-analysis performed on previously published research. Eight studies met the criteria of competitive soccer players, participation on both surfaces, and presentation of both exposure time and injury occurrence. Exposure time and injury incidence values were used to generate injury rate ratios (IRRs, AT/NG) for all injuries as well as specific injuries. Subgroup analyses were also performed by condition (match or training), gender, and age (youth or adult). The overall IRR was 0.86 (P < 0.05) suggesting a lower injury risk on AT than NG. However, there was considerable heterogeneity between studies. Analyses of individual injuries and subgroups found that in many cases IRR values were significantly less than 1.0. In no case was the IRR significantly greater than 1.0. Based on this, it appears that the risk of sustaining an injury on AT under some conditions might be lowered compared to NG. However, until more is known about how issues such as altered playing styles affect injury incidence, it is difficult to make firm conclusions regarding the influence of AT on player safety.

Changes in the anaerobic threshold in an annual cycle of sport training of young soccer players

The aim of the study was to assess changes in the anaerobic threshold of young soccer players in an annual training cycle. A group of highly trained 15-18 year old players of KKS Lech Poznań were tested. The tests included an annual training macrocycle, and its individual stages resulted from the time structure of the sports training. In order to assess the level of exercise capacities of the players, a field exercise test of increasing intensity was carried out on a soccer pitch. The test made it possible to determine the 4 millimolar lactate threshold (T LA 4 mmol · l^-1) on the basis of the lactate concentration in blood [LA], to establish the threshold running speed and the threshold heart rate [HR]. The threshold running speed at the level of the 4 millimolar lactate threshold was established using the two-point form of the equation of a straight line. The obtained indicators of the threshold running speed allowed for precise establishment of effort intensity used in individual training in developing aerobic endurance. In order to test the significance of differences in mean values between four dates of tests, a non-parametric Friedman ANOVA test was used. The significance of differences between consecutive dates of tests was determined using a post-hoc Friedman ANOVA test. The tests showed significant differences in values of selected indicators determined at the anaerobic threshold in various stages of an annual training cycle of young soccer players. The most beneficial changes in terms of the threshold running speed were noted on the fourth date of tests, when the participants had the highest values of 4.01 m · s^-1 for older juniors, and 3.80 m · s^-1 for younger juniors. This may be indicative of effective application of an individualized programme of training loads and of good preparation of teams for competition in terms of players’ aerobic endurance.

Comparação da potência anaeróbia mensurada pelo teste de RAST em diferentes condições de calçado e superfícies

INTRODUÇÃO: O Running Anaerobic Sprint Test (RAST) tem sido considerado um teste válido para avaliação anaeróbia. Entretanto, como a superfície e o calçado podem afetar alguns parâmetros mensurados durante o exercício, isso pode modificar os parâmetros do RAST. OBJETIVO: Comparar as variáveis do RAST mensuradas utilizando chuteiras na grama (RAST CG) e tênis na pista (RAST TP). MÉTODOS: Oito jogadores de futebol (da categoria sub-17) participaram do estudo. Os participantes realizaram dois RAST (intervalo > 24 h). O RAST consistiu em seis corridas máximas de 35m com 10s de intervalo passivo entre cada corrida. O tempo de cada esforço foi registrado para determinação da potência pico (PP), potência média (PM) e índice de fadiga (IF). Após o sexto esforço, amostras sanguíneas foram coletadas para determinação da lactacidemia ([Lac]). RESULTADOS: Durante o RAST TP, a PP (763,1 ± 87,2 W) e PM (621,6 ± 68,1 W) foram significativamente superiores às PP e PM mensuradas em RAST CG (PP = 667,3 ± 67,0 W e PM = 555,9 ± 74,7 W), enquanto que as [Lac] observadas em RAST TP (7,3 ± 1,8 mmol.L-1) foram significativamente inferiores às mensuradas em RAST CG (9,9 ± 3,2 mmol.L-1). No entanto, o IF não foi significativamente diferente (RAST TP = 32,5 ± 8,3%; RAST CG = 34,1 ± 6,6%). Significativas correlações foram observadas entre as PM (r = 0,90) e as [Lac] (r = 0,72). CONCLUSÃO: Podemos concluir que as variáveis do RAST são influenciadas pela superfície e calçado utilizados, com valores superiores observados em RAST TP.

The development of aerobic and skill assessment in soccer

Methods of assessing soccer players' performance have developed significantly in recent times. The fitness profiles and skill levels of a prospective elite soccer player is a valuable resource for coaches in the process of identifying talent. Traditional means to measure aerobic fitness have centred on the 'aerobic capacity' or '&OV0312;O(2max)' test (also known as the maximal oxygen consumption test) but, over time, this has been shown not to be a sensitive measure for specific aspects of soccer in a match situation. Therefore, numerous soccer-specific simulations have been designed to re-create exercise patterns similar to those experienced during a match. Some of these studies have yet to be validated, while others have been shown to result in a similar physiological load to that encountered during regular match play. Further developments have led to specifically designed intermittent sprint tests, which are used as a sensitive tool to accurately measure the fluctuations in players' ability both between and within soccer seasons. Testing procedures have also been developed that incorporate elements of both skill and physical ability. Soccer-specific field tests have been designed, incorporating skill and dynamic movements, and this opens up the possibility of teams testing the aerobic capacity of their elite players using soccer-specific movements. Valid studies assessing soccer-specific skills in an ecologically sound environment have been quite rare until recently. Some test protocols have been deemed largely irrelevant to soccer match play, while others have had limited impact on scientific literature. More recently, skill tests have been developed and shown to be valid and reliable methods of assessing soccer skill performance. Many new skill tests continue to be developed, and some have been shown to be highly reliable, but further study of these relatively novel concepts is required before a more solid recommendation can be made. Overall, while significant work has been completed to date, there is still a need for further focused investigations, which can more closely assess the physiological demands of an elite soccer player, with a particular emphasis on sport-specific exercises during the execution of soccer skills. In this regard, more reliable and specific performance tests can be designed to more efficiently assess soccer players in the future.

Heart rate responses and technical-tactical aspects of official 5-a-side youth soccer matches played on clay and artificial turf

Using a randomized crossover design, this study aimed to compare the heart rate (HR) responses and match analysis parameters (i.e., type of action; the number of players involved in an action; the number of passes performed in a collective action; precision of the shots; lost balls; ball interceptions; dribblings; and tackles) of official 5-a-side youth male soccer matches played over 2 pitch surface (i.e., clay vs. artificial turf) conditions. Twenty-two young male soccer players (age 8.3 ± 0.4 years) engaged in 2 consecutive 15-minute periods in each experimental condition. During the match, 53% of HR responses exceeded 85% of the individual HR(peak). No difference emerged between both pitch surfaces and match periods for HR and match analysis indicators. The two 15-minute periods resulted in being appropriate for 8-year-old players, in resembling the intensity of play and the intermittent nature of adult soccer. The similar HR responses and technical-tactical patterns observed on the 2 surfaces indicate that youth match play is not affected by differences in pitch surface. To support the development of individual and team skills of young soccer players, coaches are advised to prioritize game knowledge based on divergent thinking and experience, rather than traditional teaching based on instructions.

The cost of running on natural grass and artificial turf surfaces

The purpose of this study was to evaluate the metabolic cost of running (Cr) on natural grass (NG) and artificial turf (AT), compared with a hard surface (HS), that is, asphalted track. Eight amateur soccer players (mean ± SD: age 22.9 ± 2.3 years, body mass 69.0 ± 4.7 kg, and height 178 ± 5 cm) completed 9 runs (3 surfaces × 3 speeds, i.e., 2.22, 2.78, 3.33 m·s) of 6 minutes, in a random order on the different surfaces. Characteristics of the running surfaces were assessed at 3 points of each running track by measuring shock absorption and standard vertical deformation, via an 'artificial athlete' device according to FIFA protocol. No significant interactions (2-way ANOVA analysis; p = 0.38) were found between running surfaces and running speeds. A significant main effect for surface was found. The average Cr values were 4.02 ± 0.25 J·kg·L·m on HS, 4.22 ± 0.35 J·kg·L·m on NG, and 4.21 ± 0.31 J·kg·L·m on AT. The Cr was also higher at 3.33 m·s compared with the Cr measured at the other 2 running speeds. In conclusion, we found a Cr of ∼ 4.20 J·kg·L·m on both natural and artificial grass football pitches, in accordance with similar percentage shock absorption characteristics of these 2 tested surfaces. Our finding allows a better computation of the Cr on NG and AT, and supports the exclusion of the Cr as a potential factor for the higher physical effort in matches played on artificial turf, as reported by soccer players.