A Comparison of a Smartphone App with Other GPS Tracking Type Devices Employed in Football

OBJECTIVES The purpose of this study was to evaluate the use of a smartphone application in comparison against current GPS tracking type devices that are used to track players during football training and match play. Football involves repeated multi directional movements of the whole body at varying speeds and varying distances from walking to high speed running. Therefore, to evaluate validity and reliability of smartphones and elite tracker devices both were assessed and compared against each other for common metrics employed in football player activity tracking. METHODS These being, walking ≤6km/hr, jogging 6.1-12km/hr, running 12.1-18km/hr, high speed running ≥18km/hr, total distance (m), max speed (km/hr) and positional heat map. Post analysis values obtained showed that there were no significant differences between smartphones employed in the study p<0.001 95%. Furthermore, values with both the smartphone app and the GPS tracking device showed a high degree of correlation (r = 0.94-0.99, p<0.001). RESULTS The results of this study show that a smartphone application can be used for capturing data in football environments. However, caution should be taken over what data to collect and use. CONCLUSIONS That said, having the ability to easily capture such data with a smartphone can provide a practical and inexpensive tool to measure and easily visualise physical activity in football participation

The Effect of Two Speed Endurance Training Regimes on Performance of Soccer Players.

In order to better understand the specificity of training adaptations, we compared the effects of two different anaerobic training regimes on various types of soccer-related exercise performances. During the last 3 weeks of the competitive season, thirteen young male professional soccer players (age 18.5±1 yr, height 179.5±6.5 cm, body mass 74.3±6.5 kg) reduced the training volume by ~20% and replaced their habitual fitness conditioning work with either speed endurance production (SEP; n = 6) or speed endurance maintenance (SEM; n = 7) training, three times per wk. SEP training consisted of 6-8 reps of 20-s all-out running bouts followed by 2 min of passive recovery, whereas SEM training was characterized by 6-8 x 20-s all-out efforts interspersed with 40 s of passive recovery. SEP training reduced (p&lt;0.01) the total time in a repeated sprint ability test (RSAt) by 2.5%. SEM training improved the 200-m sprint performance (from 26.59±0.70 to 26.02±0.62 s, p&lt;0.01) and had a likely beneficial impact on the percentage decrement score of the RSA test (from 4.07±1.28 to 3.55±1.01%) but induced a very likely impairment in RSAt (from 83.81±2.37 to 84.65±2.27 s). The distance covered in the Yo-Yo Intermittent Recovery test level 2 was 10.1% (p&lt;0.001) and 3.8% (p&lt;0.05) higher after SEP and SEM training, respectively, with possibly greater improvements following SEP compared to SEM. No differences were observed in the 20- and 40-m sprint performances. In conclusion, these two training strategies target different determinants of soccer-related physical performance. SEP improved repeated sprint and high-intensity intermittent exercise performance, whereas SEM increased muscles' ability to maximize fatigue tolerance and maintain speed development during both repeated all-out and continuous short-duration maximal exercises. These results provide new insight into the precise nature of a stimulus necessary to improve specific types of athletic performance in trained young soccer players

Unchanged content of oxidative enzymes in fast-twitch muscle fibers and V˙O2 kinetics after intensified training in trained cyclists.

PublishedJournal ArticleThe present study examined if high intensity training (HIT) could increase the expression of oxidative enzymes in fast-twitch muscle fibers causing a faster oxygen uptake (V˙O2) response during intense (INT), but not moderate (MOD), exercise and reduce the V˙O2 slow component and muscle metabolic perturbation during INT. Pulmonary V˙O2 kinetics was determined in eight trained male cyclists (V˙O2-max: 59 ± 4 (means ± SD) mL min(-1) kg(-1)) during MOD (205 ± 12 W ~65% V˙O2-max) and INT (286 ± 17 W ~85% V˙O2-max) exercise before and after a 7-week HIT period (30-sec sprints and 4-min intervals) with a 50% reduction in volume. Both before and after HIT the content in fast-twitch fibers of CS (P < 0.05) and COX-4 (P < 0.01) was lower, whereas PFK was higher (P < 0.001) than in slow-twitch fibers. Content of CS, COX-4, and PFK in homogenate and fast-twitch fibers was unchanged with HIT. Maximal activity (μmol g DW(-1) min(-1)) of CS (56 ± 8 post-HIT vs. 59 ± 10 pre-HIT), HAD (27 ± 6 vs. 29 ± 3) and PFK (340 ± 69 vs. 318 ± 105) and the capillary to fiber ratio (2.30 ± 0.16 vs. 2.38 ± 0.20) was unaltered following HIT. V˙O2 kinetics was unchanged with HIT and the speed of the primary response did not differ between MOD and INT. Muscle creatine phosphate was lower (42 ± 15 vs. 66 ± 17 mmol kg DW(-1)) and muscle lactate was higher (40 ± 18 vs. 14 ± 5 mmol kg DW(-1)) at 6 min of INT (P < 0.05) after compared to before HIT. A period of intensified training with a volume reduction did not increase the content of oxidative enzymes in fast-twitch fibers, and did not change V˙O2 kinetics.The study was supported by Team Danmark (Danish Elite Sport Organization)

Acute simulated soccer-specific training increases PGC-1α mRNA expression in human skeletal muscle

The aim of the current study was to quantify oxygen uptake, heart rate and molecular responses of human skeletal muscle associated with mitochondrial biogenesis following an acute bout of simulated soccer training. Muscle biopsies (vastus lateralis) were obtained from nine active men immediately pre-completion, post-completion and 3 h post-completion of a laboratory-based soccer-specific training simulation on a motorised treadmill. The soccer-specific simulation was a similar intensity (55 ± 6% (Formula presented.)) and duration (60 min) as that observed in professional soccer training (e.g. standing 41%, walking 37%, jogging 11%, high-speed running 9% and sprinting 2%). Post-exercise, muscle glycogen decreased (Pre; 397 ± 86 mmol∙kg−1 dw, Post; 344 ± 64 mmol∙kg−1 dw; P = 0.03), plasma lactate increased (P −1, non-esterified fatty acids and glycerol increased (P −1 and 145 ± 54 μmol∙L−1, respectively. PGC-1α mRNA increased (P = 0.009) fivefold 3 h post-exercise. We provide novel data by demonstrating that soccer-specific training is associated with increases in PGC-1α mRNA. These data may have implications for practitioners in better understanding the metabolic and muscle responses to soccer-specific training protocols in the field

Effects of treadmill versus overground soccer match simulations on biomechanical markers of anterior cruciate ligament injury risk in side cutting.

Abstract This study aimed to investigate whether treadmill versus overground soccer match simulations have similar effects on knee joint mechanics during side cutting. Nineteen male recreational soccer players completed a 45-min treadmill and overground match simulation. Heart rate (HR) and rating of perceived exertion (RPE) were recorded every 5 min. Prior to exercise (time 0 min), at "half-time" (time 45 min) and 15 min post-exercise (time 60 min), participants performed five trials of 45° side-cutting manoeuvres. Knee abduction moments and knee extension angles were analysed using two-way repeated measures analysis of variance (α = 0.05). Physiological responses were significantly greater during the overground (HR 160 ± 7 beats ∙ min(-1); RPE 15 ± 2) than the treadmill simulation (HR 142 ± 5 beats ∙ min(-1); RPE 12 ± 2). Knee extension angles significantly increased over time and were more extended at time 60 min compared with time 0 min and time 45 min. No significant differences in knee abduction moments were observed. Although knee abduction moments were not altered over time during both simulations, passive rest during half-time induced changes in knee angles that may have implications for anterior cruciate ligament injury risk

Influence of opposition team formation on physical and skill-related performance in a professional soccer team

This study examined the influence of opposition team formation on physical and skill-related performance in a professional soccer team. Performance in forty-five French League 1 matches played over three competitive seasons (2007-08, 2008-09, and 2009-10) was analysed using multi-camera computerised tracking. Players (n=21) in the reference team (using a 4-3-3/4-5-1 formation) were analysed in matches against three opposition team formations: 4-4-2 (11 games), 4-3-3/4-5-1 (16 games) and 4-2-3-1 (18 games). Performance was compared for defending and midfield units as a whole and individually across four positions: fullbacks, central-defenders and central- and wide-midfielders. Collectively, players covered a greater total distance (p<0.05) and distance in low/moderate-intensity running (0-14.3km/h) (p<0.05) in matches against a 4-2-3-1 compared to a 4-4-2 formation. Distance covered in high-intensity (14.4-19.7km/h) and very high-intensity running (≥19.8km/h) was not affected by opposition formation. In contrast, players covered more distance in total high-intensity performance (≥14.4km/h) when the reference team was in possession against a 4-4-2 compared to a 4-2-3-1 formation (p<0.05) while more distance was run at these speeds when the reference team was out of possession against a 4-2-3-1 (p<0.01) and a 4-3-3 (p<0.05) compared to a 4-4-2 formation. Players ran less distance at low/moderate intensities in the second- versus first-half of matches against all three formations (p<0.01 to p<0.05) whereas total distance and high-intensity performance was unaffected. None of the measures of physical performance across the individual playing positions were affected by opposition team formation. Skill-related performance varied according to opposition formation: players as a whole performed more passes versus a 4-4-2 than a 4-2-3-1 (p<0.01), ground and aerial duels versus a 4-2-3-1 compared to a 4-4-2 (both p<0.01); 1-touch passes versus a 4-2-3-1 compared to a 4-4-2 (p<0.01) and a 4-3-3/4-5-1 (p<0.05). The mean number of touches per possession was highest versus a 4-4-2 compared to a 4-3-3/4-5-1 (p<0.01) and a 4-2-3-1 (p<0.01). While skill-related performance across the four individual playing positions was generally unaffected by opposition team formation, mean pass length was greater in central-midfielders against a 4-4-2 compared to 4-3-3/4-5-1 (p<0.05) and 4-2-3-1 (p<0.01) formations. In general, these findings suggest that physical performance in the reference team was not greatly affected by opposition team formation. In contrast, skill-related demands varied substantially according to opponent formation and may have consequences for tactical and technical preparation and team selection policies

The role of motion analysis in elite soccer

The optimal physical preparation of elite soccer (association football) players has become an indispensable part of the professional game especially due to the increased physical demands of match-play. The monitoring of players’ work-rate profiles during competition is now feasible through computer-aided motion analysis. Traditional methods of motion analysis were extremely labour intensive and were largely restricted to university- based research projects. Recent technological developments have meant that sophisticated systems, capable of quickly recording and processing the data of all players’ physical contributions throughout an entire match, are now being used in elite club environments. In recognition of the important role motion analysis now plays as a tool for measuring the physical performance of soccer players, this review critically appraises various motion analysis methods currently employed in elite soccer and explores research conducted using these methods. This review therefore aims to increase the awareness of both practitioners and researchers of the various motion analysis systems available, identify practical implications of the established body of knowledge, while highlighting areas that require further exploration

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 6 contemporary technologies permit an in-vivo assessment of mechanical loading on the 7 player. Objective: To quantify the influence of playing surface on the PlayerLoad elicited 8 during soccer-specific activity. Design: Repeated measures, field-based. Setting: 9 Regulation soccer pitches. Participants: 15 amateur soccer players (22.1 ± 2.4 yrs), injury 10 free with ≥ 6 yrs competitive experience. Interventions: Each player completed 11 randomised order trials of a soccer-specific field test on natural turf, astroturf and third 12 generation artificial turf. GPS units were located at C7 and the mid-tibia of each leg to 13 measure triaxial acceleration (100Hz). Main Outcome Measures: Total accumulated 14 PlayerLoad in each movement plane was calculated for each trial. Ratings of perceived 15 exertion (RPE) and visual analogue scales (VAS) assessing lower-limb muscle soreness 16 were measured as markers of fatigue. Results: ANOVA revealed no significant main 17 effect for playing surface on total PlayerLoad (P = 0.55), distance covered (P = 0.75), or 18 post-exercise measures of RPE (P = 0.98) and VAS (P = 0.61). There was a significant 19 main effect for GPS location (P &lt; 0.001), with lower total loading elicited at C7 than mid20 tibia (P &lt; 0.001), but with no difference between limbs (P = 0.70). There was no unit 21 placement x surface interaction (P = 0.98). There was also a significant main effect for 22 GPS location on the relative planar contributions to loading (P &lt; 0.001). Relative planar 23 contributions to loading in the AP:ML:V planes was 25:27:48 at C7 and 34:32:34 at mid24 tibia. Conclusions: PlayerLoad metrics suggest that playing surface does not influence 25 mechanical loading during soccer-specific activity (not including tackling). Clinical 2 26 reasoning should consider that PlayerLoad magnitude and axial contributions were 27 sensitive to unit placement, highlighting opportunities in the objective monitoring of load 28 during rehabilitation

Are Current Physical Match Performance Metrics in Elite Soccer Fit for Purpose or is the Adoption of an Integrated Approach Needed?

Time-motion analysis is a valuable data-collection technique used to quantify the physical match performance of elite soccer players. For over 40 years researchers have adopted a 'traditional' approach when evaluating match demands by simply reporting the distance covered or time spent along a motion continuum of walking through to sprinting. This methodology quantifies physical metrics in isolation without integrating other factors and this ultimately leads to a one-dimensional insight into match performance. Thus, this commentary proposes a novel 'integrated' approach that focuses on a sensitive physical metric such as high-intensity running but contextualizes this in relation to key tactical activities for each position and collectively for the team. In the example presented, the 'integrated' model clearly unveils the unique high-intensity profile that exists due to distinct tactical roles, rather than one-dimensional 'blind' distances produced by 'traditional' models. Intuitively this innovative concept may aid the coaches understanding of the physical performance in relation to the tactical roles and instructions given to the players. Additionally, it will enable practitioners to more effectively translate match metrics into training and testing protocols. This innovative model may well aid advances in other team sports that incorporate similar intermittent movements with tactical purpose. Evidence of the merits and application of this new concept are needed before the scientific community accepts this model as it may well add complexity to an area that conceivably needs simplicity