Muscle injury rates in professional football increase with fixture congestion: an 11-year follow-up of the UEFA Champions League injury study

Quality of functional movement patterns and injury examination in elite-level male professional football players

The purpose of this study is to examine the quality of functional movement patterns among one of Hungary's first league soccer clubs, where the elite male football players (N = 20) utilize the well-established Functional Movement Screen™ (FMS) system; a comprehensive functional program designed to determine and identify the quality of movement and the greatest risk factors for non-contact injuries. Furthermore, an additional purpose of this program is to examine injuries over the course of 6 competitive months. Focusing on the mechanisms of injuries and their causes in the lower extremities during this period is one of the key objectives. Over the course of 6 months we found significant differences between ankle injuries and the FMS Hurdle Step exercise (p < 0.05), and the FMS Deep Squat exercise and knee and hip injuries (p < 0.05). The FMS pre-screening system found lower limb asymmetry present in 40% of the participants. The authors believe that the importance of preventative measures and structural sport specific pre-screening cannot be overemphasized, and that there is a growing need for further transparent research in this field in order to be more effective with regard to programs dedicated to injury prevention and the enhancement players' physical performance.

The impact of in-season national team soccer play on injury and player availability in a professional club

This study investigated the impact of in-season national team duty on injury rates and player availability in a professional soccer club. Time-loss injuries and exposure time during club and national team duties were recorded prospectively over 5 seasons (2009-2014). A time-loss injury was sustained by 37.7% of squad members participating in national duty, all injuries occurring in match-play. The incidence (per 1000 h exposure) for national team player match-play injuries did not differ (P = 0.608) to that for all players in club competitions: 48.0 (95% CI 20.9-75.5) vs. 41.9 (95% CI 36.5-47.4), incidence rate ratio = 1.2 (CI: 0.8-2.4). The majority (58%) of national team injuries resulted in a layoff ≤1 week. Of all working days lost to injury generally, 5.2% were lost through injury on national duty. Injury incidence in the week following national duty was comparable (P = 0.818) in players participating or not: 7.8 (95% CI 3.6-12.0) vs. 7.1 (95% CI: 4.6-9.6), incidence rate ratio = 1.1 (CI: 0.7-2.7). While approximately 40% of participating players incurred a time-loss injury on national duty, no training injuries were sustained and injuries made up a negligible part of overall club working days lost to injury. Following duty, players had a similar injury risk to peers without national obligations.

Reliability of externally fixed dynamometry hamstring strength testing in elite youth football players

OBJECTIVES

To investigate inter and intra-tester reliability of an externally fixed dynamometry unilateral hamstring strength test, in the elite sports setting.

DESIGN

Reliability study.

METHODS

Sixteen, injury-free, elite male youth football players (age=16.81±0.54 years, height=180.22±5.29cm, weight 73.88±6.54kg, BMI=22.57±1.42) gave written informed consent. Unilateral maximum isometric peak hamstring force was evaluated by externally fixed dynamometry for inter-tester, intra-day and intra-tester, inter-week reliability. The test position was standardised to correlate with the terminal swing phase of the gait running cycle.

RESULTS

Inter and intra-tester values demonstrated good to high levels of reliability. The intra-class coefficient (ICC) for inter-tester, intra-day reliability was 0.87 (95% CI=0.75-0.93) with standard error of measure percentage (SEM%) 4.7 and minimal detectable change percentage (MDC%) 12.9. Intra-tester, inter-week reliability results were ICC 0.86 (95% CI, 0.74-0.93), SEM% 5.0 and MDC% 14.0.

CONCLUSIONS

This study demonstrates good to high inter and intra-tester reliability of isometric externally fixed dynamometry unilateral hamstring strength testing in the regular elite sport setting involving elite male youth football players. The intra-class coefficient in association with the low standard error of measure and minimal detectable change percentages suggest that this procedure is appropriate for clinical and academic use as well as monitoring hamstring strength in the elite sport setting.

Injury risk factors, screening tests and preventative strategies: a systematic review of the evidence that underpins the perceptions and practices of 44 football (soccer) teams from various premier leagues

Purpose

To systematically review the scientific level of evidence for the ‘Top 3’ risk factors, screening tests and preventative exercises identified by a previously published survey of 44 premier league football (soccer) teams. Also, to provide an overall scientific level of evidence and graded recommendation based on the current research literature.

Methods

A systematic literature search (Pubmed [MEDLINE], SportDiscus, PEDRO and Cochrane databases). The quality of the articles was assessed and a level of evidence (1++ to 4) was assigned. Level 1++ corresponded to the highest level of evidence available and 4, the lowest. A graded recommendation (A: strong, B: moderate, C: weak, D: insufficient evidence to assign a specific recommendation) for use in the practical setting was given.

Results

Fourteen studies were analysed. The overall level of evidence for the risk factors previous injury, fatigue and muscle imbalance were 2++, 4 and ‘inconclusive’, respectively. The graded recommendation for functional movement screen, psychological questionnaire and isokinetic muscle testing were all ‘D’. Hamstring eccentric had a weak graded ‘C’ recommendation, and eccentric exercise for other body parts was ‘D’. Balance/proprioception exercise to reduce ankle and knee sprain injury was assigned a graded recommendation ‘D’.

Conclusions

The majority of perceptions and practices of premier league teams have a low level of evidence and low graded recommendation. This does not imply that these perceptions and practices are not important or not valid, as it may simply be that they are yet to be sufficiently validated or refuted by research.

Fast bowling match workloads over 5-26 days and risk of injury in the following month

OBJECTIVES

This study examined whether high match fast bowling workloads in the short to medium term were associated with increased bowling injury rates.

DESIGN

Prospective cohort study.

METHODS

Over a 15 year period, workload patterns for 235 individual fast bowlers during time periods from 5 to 26 days were examined to consider whether there was an increased injury rate during the month (28 days) subsequent to the workload.

RESULTS

Fast bowlers who bowled more than 50 match overs in a 5 day period had a significant increase in injury over the next month compared to bowlers who bowled 50 overs or less RR 1.54 (95% CI 1.04-2.29). For periods ranging from 12 to 26 days, there was no statistically-significant increase in injury over the next month from exceeding thresholds of certain amounts of overs, although bowlers who bowled more than 100 overs in 17 days had a non-significant increase in injury over the next month RR 1.78 (95% CI 0.90-3.50).

CONCLUSION

There were no statistically-significant increases in subsequent injury risk for high workloads for periods of 12-26 days, although exceeding 100 overs in 17 days (or less) was associated with higher injury rates. Compression of cricket fixtures is likely to have only a minimal contribution to increased fast bowling injury rates being seen in the T20 era (along with sudden workload increases due to transferring between forms of the game, which has been previously established as a major contributor).

The effect of short-term interval training during the competitive season on physical fitness and signs of fatigue: a crossover trial in high-level youth football players

PURPOSE

To analyze performance and fatigue effects of small-sided games (SSG) vs high-intensity interval training (HIIT) performed during a 4-wk in-season period in high-level youth football.

METHODS

Nineteen players from 4 youth teams (16.5 [SD 0.8] y, 1.79 [0.06] m, 70.7 [5.6] kg) of the 2 highest German divisions completed the study. Teams were randomly assigned to 1 of 2 training sequences (2 endurance sessions per wk): One training group started with SSG, whereas the other group conducted HIIT during the first half of the competitive season. After the winter break, training programs were changed between groups. Before and after the training periods the following tests were completed: the Recovery-Stress Questionnaire for Athletes, creatine kinase and urea concentrations, vertical-jump height (countermovement jump [CMJ], drop jump), straight sprint, agility, and an incremental field test to determine individual anaerobic threshold (IAT).

RESULTS

Significant time effects were observed for IAT (+1.3%, η(p)(2) = .31), peak heart rate (-1.8%, η(p)(2) = .45), and CMJ (-2.3%, η(p)(2) = .27), with no significant interaction between groups (P > .30). Players with low baseline IAT values (+4.3%) showed greater improvements than those with high initial values (± 0.0%). A significant decrease was found for total recovery (-5.0%, η(p)(2) = .29), and an increase was found for urea concentration (+9.2%, η(p)(2) = .44).

CONCLUSION

Four weeks of in-season endurance training can lead to relevant improvements in endurance capacity. The decreases in CMJ height and total-recovery score together with the increase in urea concentration might be interpreted as early signs of fatigue. Thus, the danger of overtaxing players should be considered.