Effects of football simulated fatigue on neuromuscular function and whole-body response to disturbances in balance

Quantifying the Performance of Professional Athletes Following Traumatic Tibial Fractures

INTRODUCTION

A tibial fracture is an uncommon, yet severe injury that occurs in professional athletes within all major sports leagues. These injuries are often debilitating for professional athletes and can require extensive rehabilitation prior to returning to play. The purpose of this study is to investigate the impact of a tibial fracture on athletic performance in all four major United States sports leagues.

METHODS

A publicly available professional sports database, Pro Sports Transactions, was queried for tibial injuries from January 01, 2015, to May 31, 2023. The search included all four major U.S. sports leagues. To quantify and compare athletic ability before and after injury, performance-based statistics were collected from standardized player ratings in periods surrounding the date of injury. The percent change in player performance was measured and stratified. The Pearson correlation test was used to analyze player demographics.

RESULTS

There were a total of 24 professional athletes who suffered 28 confirmed tibial fractures across all leagues. Upon return, there was a 14.7% decrease in overall player performance across all leagues. National Basketball Association, National Football League, and National Hockey League athletes had a decrease of 34.5%, 29.1%, and 14.2%, respectively, following their return to play. Major League Baseball players demonstrated an 8.1% increase in player performance following their recovery from tibial fracture.

CONCLUSION

Players who suffer tibial fractures often undergo immediate surgery and, in unfortunate cases, may require multiple subsequent procedures. Additionally, athletes spend several months recovering prior to their return. Upon return, athletes' performance may be decreased; however, further study is required to strengthen the association between player performance and tibial fracture recovery.

Effects of repeated sprinting on hamstring shear modulus pattern and knee flexor neuromuscular parameters

The purpose of the present study was to examine the acute effects of a maximum repeated sprint protocol on (1) hamstring shear modulus and (2) knee flexor neuromuscular parameters such as peak torque (PT) and rate of torque development (RTD). Muscle shear modulus was assessed in 18 healthy males using shear wave elastography at rest and during 30° isometric knee flexion at 20% of maximal voluntary isometric contraction, before and after a 10 × 30 m repeated sprint protocol. There was a 9% decrease in average speed between the fastest and slowest sprint (p < 0.001; d = 2.27). A pre-post decrease was observed in PT (p = 0.004; η2p = 0.399) and in the 0-50 ms (p = 0.042; η2p = 0.222), and 50-100 ms (p = 0.028; η2p = 0.254) RTD periods. For the active shear modulus, the only significant change after the sprint task was in the biceps femoris long head (BFlh) with an increase of 10% (Pre: 26.29 ± 8.89 kPa; Post: 28.93 ± 8.31 kPa; p = 0.015; d = 0.31). The present study provides evidence that repeated sprinting leads to significant decreases in average speed, PT, early RTD (0-50 ms; 50-100 ms), and to an increase in BFlh active shear modulus without changing the shear modulus of the other hamstrings muscles.

Validation of Instrumented Football Shoes to Measure On-Field Ground Reaction Forces

Ground reaction forces (GRF) have been widely studied in football to prevent injury. However, ambulatory tools are missing, posing methodological limitations. The purpose of this study was to assess the validity of an innovative football shoe measuring normal GRF (nGRF) directly on the field through instrumented studs. A laboratory-based experiment was first conducted to compare nGRF obtained with the instrumented shoe (IS) to vertical GRF (vGRF) obtained with force platform (FP) data, the gold standard to measure vGRF. To this aim, three subjects performed 50 steps and 18 counter-movement jumps (CMJs). Secondly, eleven subjects completed running sprints at different velocities on a football field, as well as CMJs, while wearing the IS. Good to excellent agreement was found between the vGRF parameters measured with the FP and the nGRF measured by the IS (ICC > 0.75 for 9 out of 11 parameters). Moreover, on-field nGRF patterns demonstrated a progressive and significant increase in relation with the running velocity (p < 0.001). This study demonstrated that the IS is a highly valid tool to assess vGRF patterns on a football field. This innovative way to measure vGRF in situ could give new insights to quantify training load and detect neuromuscular fatigue.

Epidemiology of Tibial Fractures in Professional American Football Athletes From 2013 to 2019

Background:

Lower extremity injuries occur with high frequency in National Football League (NFL) athletes and cause high burden to players and teams. Tibial fractures are among the most severe lower extremity injuries sustained in athletes and are associated with prolonged time loss from sport.

Purpose:

To determine the number of tibial fractures in NFL athletes from the 2013 to 2019 NFL seasons and describe athlete demographics, fracture characteristics, and details of injury onset.

Study Design:

Case series; Level of evidence, 4.

Methods:

A retrospective review of the NFL injury database was performed to identify all NFL athletes sustaining tibial fractures over the 2013 to 2019 NFL seasons. Athlete characteristics, injury characteristics, days missed, and treatment (operative vs nonoperative) were examined. Descriptive statistics were used to calculate means, standard deviations, ranges, and percentages.

Results:

A total of 64 tibial fractures were identified in 60 athletes, resulting in a median loss of 74 days. Defensive secondary athletes had the highest number of injuries (n = 10; 16%), followed by running backs (n = 9; 14%), while 61% of these injuries occurred during NFL regular-season games, primarily between weeks 13 and 17. The most commonly reported activity during injury was athletes being tackled, with a direct impact to the tibia being the most common mechanism of injury. Lateral tibial plateau fractures were the most frequently reported, while distal tibial fractures resulted in the greatest number of days lost. The median time lost for injuries requiring surgery was 232 days compared with 56 days for injuries treated using conservative management.

Conclusion:

The highest proportion of tibial fractures were injuries to defensive secondary athletes and athletes being tackled while sustaining a direct impact to the leg, primarily to the lateral tibial plateau. Tibial fracture injuries were commonly sustained during NFL regular-season games, primarily during the final 4 weeks of the NFL regular season. Further investigations examining performance and career longevity in athletes sustaining tibial fractures are warranted to help improve the health and safety of NFL athletes.

Rating of perceived exertion (RPE) in studies of fatigue-induced postural control alterations in healthy adults: Scoping review of quantitative evidence

BACKGROUND

Amongst the literature researching the effects of exercise-induced fatigue on postural control in healthy adults, many studies have used the Borg scales to document the rating of perceived exertion (RPE) and have shown a broad range of RPE values. Our main aim was to map fatigue-induced RPE values in included publications. Secondary aims were to summarize the preference and purpose for the use of Borg scales within the included publications and to explore the potential associations between fatigue-induced RPE values and postural control changes.

METHODS

Five databases (Ovid Medline, PubMed, CINAHL, Scopus, and SPORTDiscus) were systematically searched for synthesizing data among the publications that reported RPE values on the Borg RPE- and Category-Ratio (CR) 10 scales and also found fatigue effects on postural control in healthy adults. Spearman's rank correlations were conducted to assess potential associations between fatigue-induced RPE values and maximal postural control changes across the included publications (group data).

RESULTS

45 of 51 studies included in this review reported maximal RPE values following exercise and ranged from 10.4-20 (6-20 Borg RPE) or 0.9-10 (CR10) indicating "very light" or "very weak" to "maximal" exertions. The 6-20 Borg and CR10 scales were mainly used to assess cardiovascular and muscular exertion, respectively. The scales were used mostly to estimate fatigue levels (n = 45), and to a lesser extent to produce a specific exercise intensity (n = 5) and as the criterion for exercise termination (n = 1). In general, there was no significant association between RPE and postural control changes across studies.

CONCLUSION

The broad range of RPE values and weak correlations may suggest that various fatigue levels can lead to postural control changes. However, one should be careful in comparing the extent of fatigue from RPE values and its potential effect on postural control in the light of many confounding factors.

The Effect of Combining Plyometrics Exercises and Balance Exercises in Improving Dynamic Balance among Female College Athletes: A Randomized Controlled Trial

INTRODUCTION

Plyometrics and balance exercises have been shown to reduce lower limb injury incidence. The effects of combining these exercises on dynamic balance have not been investigated.

OBJECTIVE

This study aimed to evaluate the effect of plyometrics and balance exercises and a combination of both exercises on postural stability among female athletes compared to those who did not perform any specific exercise (control).

DESIGN

Randomized controlled trial.

SETTING

Sports Medicine Laboratory.

PARTICIPANTS

Two hundred female athletes aged 21.9±2.4 years were randomly assigned to a plyometrics exercises group (n = 50), a balance exercises group (n = 50), a combination of both exercises group (n = 50), or a control group (n = 50). One hundred seventy-nine female college athletes completed the study.

INTERVENTIONS

Plyometrics exercises, balance exercises and a combination of both exercises.

OUTCOME MEASURES

Limits of stability, which was assessed using the Biodex Stability System to assess the performance of the dynamic balance. It was measured pre and post-intervention after six weeks.

RESULTS

There were no differences in baseline data between groups (p = .557). All groups showed significant improvements in limits of stability (p < .001). The most marked improvement in the limits of stability was shown in the combination group compared to the control group (MD = 4.1 %, 95% CI [2.8, 5.3], p < .001).

CONCLUSIONS

Combining plyometrics and balance exercises significantly increases the dynamic balance performance post-intervention among female athletes compared to the control group. This article is protected by copyright. All rights reserved.

Acute Hamstring Injury Prevention Programs in Eleven-a-Side Football Players Based on Physical Exercises: Systematic Review

(1) Objective: To analyze the exercise programs used to prevent of acute hamstring injuries in eleven-a-side football players, and their effectiveness. (2) Methods: A systematic review (PRISMA) was conducted (2008-2020), including RCTs, that exclusively used physical exercises as a prevention method. (3) Results: Ten studies were selected considering 14 interventions, including nine different programs: FIFA11+ (11+), Harmoknee, eccentric Nordic Hamstring Exercise (NHE) exclusively, with eccentric exercises, with stretching or with proprioceptive, New Warm-up Program (NWP), Bounding Exercise Program (BEP), the only one with no positive results, and proprioceptive exercises. Incidence of injuries and strength were the most considered variables, both with favorable evidences. Programs including NHE, which assessed injury incidence, were always effective. The 11+ program was effective in injury incidence and strength; NWP was effective in balance, stability, and strength. (4) Conclusions: The exercise programs discussed were effective to prevent acute hamstring injuries in football players except BEP and partially Harmoknee. Exercises mostly used to reduce the risk of hamstring injuries are those of eccentric force due to its functionality, especially NHE. Only concentric contractions and isometric contractions obtained significant favorable results. The most complete and promising programs were 11+ (in injury incidence and strength) and NWP (strength, balance, and stability). NWP was the best in strength.

Delayed ankle muscle reaction time in female amateur footballers after the first 15 min of a simulated prolonged football protocol

PURPOSE

Ankle sprain injury rate is reported to be higher towards the end of a football match. Muscle fatigue may contribute to the delayed muscle reaction and subsequent injury. This study investigated the ankle muscle reaction time during a simulated, prolonged football protocol.

METHODS

Seven amateur female football players participated in a 105-min simulated, prolonged football protocol. An ankle muscle reaction test was conducted with a pair of ankle sprain simulators at a scheduled interval every 15-min. The reaction times of peroneus longus, tibialis anterior, and lateral gastrocnemius were collected using an electromyography system sampling at 1000 Hz. Repeated measures one-way multivariate analysis of variance with post-hoc paired t-tests were conducted to evaluate if the reaction time at each time point significantly differed from baseline. Statistical significance was set at p < 0.05 level.

RESULTS

Reaction times started from 40.5-47.7 ms at baseline and increased to 48.6-55.7 ms at the end. Reaction times significantly increased in all muscles after the first 15 min except for the dominant lateral gastrocnemius. Increased reaction times were seen in the non-dominant limb after 60 min for tibialis anterior, after 75 min for peroneus longus, and after 90 min for the lateral gastrocnemius.

CONCLUSIONS

Delayed reaction time of the ankle muscles were found after the first 15 min and in the final 45 min of a simulated prolonged football protocol. Strategies for injury prevention should also focus on tackling the delayed ankle muscle reaction time in the acute phase (the first 15 min), in addition to the latter minutes in the second half.

LEVEL OF EVIDENCE

Controlled laboratory study, Level V.