Sprint Variables Are Associated with the Odds Ratios of Non-Contact Injuries in Professional Soccer Players

Are Metabolic Power Distribution and Accelerometer-Based Global Positioning System Variables Associated With Odds Ratios of Noncontact Injuries in Professional Soccer Players?

ABSTRACT

Nobari, H, Alves, AR, Abbasi, H, Khezri, D, Zamorano, AD, and Bowman, TG. Are metabolic power distribution and accelerometer-based GPS variables associated with odds ratios of noncontact injuries in professional soccer players? J Strength Cond Res 37(9): 1809-1814, 2023-The present study was intended to i) investigate the relationship between metabolic power average (MPA), acceleration (AcZ) and deceleration (DcZ) zones, and their differences (Δ) on 3 load levels with noncontact injuries in professional players throughout a full soccer season and ii) to analyze the injury risk associated between high-load versus low-load levels for each of the aforementioned parameters with odds ratios (OR) and relative risk (RR), respectively. Twenty-one professional soccer players (age = 28.3 ± 3.9 years) were monitored during a full season (48 weeks) through global positioning system (GPS). A relationship between MPA and accelerometer-based GPS, mainly in explosive actions (i.e., AcZs and DcZs), was found. A higher incidence of injuries in the high-load weeks compared with the low-load weeks were reported (mainly in MPA, AcZ1, AcZ2, and DcZ3 variables). Moreover, significant means of OR (mean = 4.3) and RR (mean = 2.6) of noncontact injuries were established in intense periods with higher metabolic load (i.e., power accelerations, AcZ1, x2 = 0.022). Our results may be useful for coaches, sports scientists, and researchers regarding the optimization of the athletes' performance, as well as providing insights about the impact of intense exercise.

Athlete External Loads Across a Collegiate Men's Lacrosse Season

ABSTRACT

Fields, JB, Jones, MT, Feit, MK, and Jagim, AR. Athlete external loads across a collegiate men's lacrosse season. J Strength Cond Res XX(X): 000-000, 2022-Tracking and quantifying athlete workload may provide insight into best practice periodization strategies and workload management. Limited information exists detailing the external demands associated with collegiate men's lacrosse. Therefore, the purpose of this study was to investigate and compare practice, game, and positional differences across a lacrosse season. Male collegiate lacrosse athletes (n = 17; body mass: 79.9 kg ± 9.7 kg; body fat %: 14.7 ± 3.8%) wore a global positional system device during practices (n = 66) and games (n = 19). External load metrics were total distance (TD), sprint distance (SD), accelerations (>3 m·s-2), sprint efforts, player load (PL), PL/min, and top speed. Multiple analysis of variances assessed differences in external loads across session (practice versus game) and sport position (attackers, midfielders, and defenders). A 3 × 4 analysis of variance was used to determine a position-by-time (first quarter [Q1], second quarter [Q2], third quarter [Q3], and fourth quarter [Q4]) interaction (p < 0.05). Total distance (p < 0.001, η2: 0.047), SD (p < 0.001, η2: 0.093), sprint efforts (p < 0.001, η2: 0.077), PL (p < 0.001, η2: 0.022), and top speeds (p < 0.001, η2: 0.086) were all higher in games compared with practices. Attackers and defenders covered more TD (p < 0.001, η2 = 0.0257), accelerations (p < 0.001, η2 = 0.126), PL (p < 0.001, η2 = 0.233), and PL/min (p < 0.001, η2 = 0.193) than midfielders. Attackers and midfielders covered more SD (p = 0.002 η2 = 0.043), sprint efforts (p < 0.001, η2 = 0.053), and achieved higher top speed (p < 0.001, η2 = 0.0063) than defenders. Volume and intensity metrics declined by Q4 in attackers and defenders (p < 0.05), whereas external load measures did not differ across quarters for midfielders. Monitoring in-game external loads can assist coaches with individualizing training programs and preparing athletes for game demands.

A Systematic Review of the Relationship between Workload and Injury Risk of Professional Male Soccer Players

The number of studies on the relationship between training and competition load and injury has increased exponentially in recent years, and it is also widely studied by researchers in the field of professional soccer. In order to provide practical guidance for workload management and injury prevention in professional athletes, this study provides a review of the literature on the effect of load on injury risk, injury prediction, and interpretation mechanisms. The results of the research show that: (1) It appears that short-term fixture congestion may increase the match injury incidence, while long-term fixture congestion may have no effect on both the overall injury incidence and the match injury incidence. (2) It is impossible to determine conclusively whether any global positioning system (GPS)-derived metrics (total distance, high-speed running distance, and acceleration) are associated with an increased risk of injury. (3) The acute:chronic workload ratio (ACWR) of the session rating of perceived exertion (s-RPE) may be significantly associated with the risk of non-contact injuries, but an ACWR threshold with a minimum risk of injury could not be obtained. (4) Based on the workload and fatigue recovery factors, artificial intelligence technology may possess good predictive power regarding injury risk.

Workload is associated with the occurrence of non-contact injuries in professional male soccer players: A pilot study

Injuries in professional soccer are a significant concern for teams, and they are caused amongst others by high training load. This cohort study describes the relationship between workload parameters and the occurrence of non-contact injuries, during weeks with high and low workload in professional soccer players throughout the season. Twenty-one professional soccer players aged 28.3 ± 3.9 yrs. who competed in the Iranian Persian Gulf Pro League participated in this 48-week study. The external load was monitored using global positioning system (GPS, GPSPORTS Systems Pty Ltd) and the type of injury was documented daily by the team's medical staff. Odds ratio (OR) and relative risk (RR) were calculated for non-contact injuries for high- and low-load weeks according to acute (AW), chronic (CW), acute to chronic workload ratio (ACWR), and AW variation (Δ-Acute) values. By using Poisson distribution, the interval between previous and new injuries were estimated. Overall, 12 non-contact injuries occurred during high load and 9 during low load weeks. Based on the variables ACWR and Δ-AW, there was a significantly increased risk of sustaining non-contact injuries (p &lt; 0.05) during high-load weeks for ACWR (OR: 4.67), and Δ-AW (OR: 4.07). Finally, the expected time between injuries was significantly shorter in high load weeks for ACWR [1.25 vs. 3.33, rate ratio time (RRT)] and Δ-AW (1.33 vs. 3.45, RRT) respectively, compared to low load weeks. The risk of sustaining injuries was significantly larger during high workload weeks for ACWR, and Δ-AW compared with low workload weeks. The observed high OR in high load weeks indicate that there is a significant relationship between workload and occurrence of non-contact injuries. The predicted time to new injuries is shorter in high load weeks compared to low load weeks. Therefore, the frequency of injuries is higher during high load weeks for ACWR and Δ-AW. ACWR and Δ-AW appear to be good indicators for estimating the injury risk, and the time interval between injuries.

Effects of small-sided games and running-based high-intensity interval training on body composition and physical fitness in under-19 female soccer players

Background

The aim of this study was to compare the effects of small-sided games (SSGs) and running-based high-intensity interval training (HIIT) on the body composition and physical fitness of youth female soccer players.

Methods

This study followed a randomized parallel study design. Twenty-four female soccer players (age: 18.63 ± 2.36 years) were randomly allocated to two training groups (SSG, n = 12; and HIIT, n = 12). The training intervention had a duration of eight weeks, consisting of three training sessions per week. Players were assessed twice (pre- and post-intervention) for anthropometrics, vertical (countermovement jumps, CMJ; and drop jumps, DJ) and horizontal jumping (single, triple and crossover hop), sprinting (10- and 30-m), change-of-direction (COD), COD deficit and final velocity at 30–15 Intermittent Fitness Test (V_IFT). A covariance analysis (ANCOVA) was used to determine differences between the groups in the effect on post-intervention by controlling for covariates (pre-intervention). The within-group analysis (time) was performed using a paired t-test, while the between-group analysis per assessment moment was performed using an independent t-test.

Results

The between-group analysis with ANCOVA revealed that there are no significant differences between the SSG and HIIT groups in the post-intervention for any outcome (p > 0.05). The within-group analysis revealed significant improvements in both the SSG and HIIT groups in CMJ (p < 0.05), single, triple and crossover hops (p < 0.05), RSI DJ 30-cm and RSI DJ 40-cm (p < 0.05), VIFT (p < 0.05) and COD (p < 0.05).

Conclusions

SSG and HIIT are both effective for improving vertical and horizontal jumping ability, change-of-direction, and aerobic capacity status measured at a progressive and intermittent multistage test in youth soccer players.

Comparison of Measurements of External Load between Professional Soccer Players

Background: The excessive and rapid increases in training load (TL) may be responsible for most non-contact injuries in soccer. This study’s aims were to describe, week(w)-by-week, the acute (AW), chronic (CW), acute:chronic workload ratio (wACWR), total distance (wTD), duration training (wDT), sprint total distance (wSTD), repeat sprint (wRS), and maximum speed (wMS) between starter and non-starter professional soccer players based on different periods (i.e., pre-, early-, mid-, and end-season) of a full-season (Persian Gulf Pro League, 2019−2020). Methods: Nineteen players were divided according to their starting status: starters (n = 10) or non-starters (n = 9). External workload was monitored for 43 weeks: pre- from w1−w4; early- from w5−w17; mid- from w18−w30, and end-season from w31−w43. Results: In starters, AW, CW, and wACWR were greater than non-starters (p < 0.05) throughout the periods of early- (CW, p ≤ 0.0001), mid- (AW, p = 0.008; CW, p ≤ 0.0001; wACWR, p = 0.043), or end-season (AW, p = 0.035; CW, p = 0.017; wACWR, p = 0.010). Starters had a greater wTD (p ≤ 0.0001), wSTD (p ≤ 0.0001 to 0.003), wDT (p ≤ 0.0001 to 0.023), wRS (p ≤ 0.0001 to 0.018), and wMS (p ≤ 0.0001) than non-starters during early-, mid-, and end-season. Conclusion: Starters experienced more CW and AW during the season than non-starters, which underlines the need to design tailored training programs accounting for the differences between playing status.

Acute and Chronic Workload Ratios of Perceived Exertion, Global Positioning System, and Running-Based Variables Between Starters and Non-starters: A Male Professional Team Study

The study aim was 2-fold (i) to describe and compare the in-season variations of acute: chronic workload ratio (ACWR) coupled, ACWR uncoupled, and exponentially weighted moving average (EWMA) through session-rated perceived exertion (s-RPE), total distance (TD), high-speed running distance (HSRD), and sprint distance across different periods of a professional soccer season (early, mid, and end-season) between starters and non-starters; (ii) to analyze the relationship the aforementioned measures across different periods of the season for starters and non-starters. Twenty elite soccer players (mean ± SD age, 29.4 ± 4.4 y; height, 1.8 ± 0.1 m; and body mass, 74.8 ± 2.3 kg). They were divided into starter and non-starter groups and were evaluated for 20 weeks. ACWR had general changes throughout the season. At the beginning and end of the mid-season, the highest ACWR was observed in three parameters: s-RPE, TD, and HSRD. ACWR and EWMA through sprint distance were higher at the beginning of the early-season than at any other time of the season.

The ACWR coupled of s-RPE shows a significant higher value for non-starters than starters (p = 0.015; g = −1.01 [−1.98, −0.09]) and the ACWR coupled of TD shows a significant higher value for starters than non-starters in early-season (p < 0.01; g = 3.01 [1.78, 4.46]) and shows a significant higher value for non-starters than starters in mid-season (p < 0.01; g = −2.52 [−3.83, −1.39]), and end-season (p < 0.01; g = −2.57 [−3.89, −1.43]). While the EWMA of TD shows a significant higher value for starters than non-starters in early-season (p < 0.01; g = 2.25 [1.17, 3.49]) and mid-season (p < 0.01; g = 2.42 [1.31, 3.71]), and shows a significant higher value for non-starters than starters in end-season (p < 0.01; g = −2.23 [−3.47, −1.16]). Additionally, we found some correlations between external and internal load measures during three periods of the in-season. The study’s main finding was that the indexes of ACWR and EWMA were useful to detect differences between period and between playing status with the exception for the sprint variable. In addition, the necessary work for non-starter players’ improvement is not done during training, and these players lose their readiness as the season progresses. Consequently, these players perform poorly during the match. Therefore, coaches and their staff should consider devising new activities to keep non-starter players physically fit. This deficit must be accounted for in training because they compete in fewer matches and have less burden than starters.

Effect of Combined Balance Exercises and Kinesio Taping on Balance, Postural Stability, and Severity of Ankle Instability in Female Athletes with Functional Ankle Instability

Ankle sprain is a common musculoskeletal injury, and recurrent ankle sprains often lead to ankle instability. This study aimed to examine whether a 6-week balance training on a wobble board (WB) combined with kinesio taping (KT) is effective in improving balance, postural stability, and ankle stability among female athletes with functional ankle instability (FAI). Twenty-four female athletes with FAI were randomly assigned to study (SG) or control groups (CG). SG attended a 6-week training protocol of combined balance training on the wobble board with KT applied to ankles during exercise. CG only went through a 6-week balance training procedure that was the same as the SG. Before and after the training program, balance and postural stability and the severity of ankle instability were assessed by single-leg Biodex Balance system and Cumberland Ankle Instability Tool (CAIT), respectively. The analysis revealed that the scores of balance and postural stability decreased after the 6-week training for CG (p = 0.002) and SG (p = 0.001), which indicates an improvement for these variables, and the score of CAIT increased, which means the severity of instability reduced (p = 0.001 for both groups). Significant between-group differences were found for balance and postural stability (t = 2.79, p = 0.011, g = −1.99) and the severity of instability (t = 2.082, p = 0.049, g = 1.36), favoring SG compared with CG. This study showed that the addition of KT to balance training is more effective than balance training alone in improving balance, postural stability, and severity of ankle instability in female athletes with FAI. Our findings could provide a preliminary reference for designing combined balance and KT programs for delivering health benefits to females with FAI.

Wearable Inertial Measurement Unit to Measure External Load: A Full-Season Study in Professional Soccer Players

The aim of this study was to describe weekly acute workload (wAW), chronic workload (wCW), acute: chronic workload ratio (wACWR), training monotony (wTM), and training strain (wTS) variations over a full season across playing positions. Twenty-one professional soccer players were daily monitored during 48 consecutive weeks. Total distance, sprint total distance (STD), high-speed running distance (HSRd), maximum speed, number of the repeated sprints, and body load (BL) were obtained during training and matches using a Wearable Inertial Measurement Unit. The wAW was determined for each external load measure. The wCW, wACWR, and wTM were calculated based on BL metric. Higher values of weekly STD were observed in lateral defenders/wingers (LDW) compared to central defenders/forwards (CDF) (p = 0.009; ES = Large) and midfielders (MDF) (p = 0.034; ES = Large). Additionally, weekly HSRd was higher in LDW vs. CDF (p = 0.016; ES = Large) and MDF (p = 0.011; ES = Large). The CDF presented a lower weekly number of repeated sprints than LDW (p = 0.021; ES = Large). In conclusion, weekly external load metrics were position-dependent over the season. Moreover, LDW a presented greater weekly STD, HSRd, and number of repeated sprints compared to other positions.