Low Horizontal Force Production Capacity during Sprinting as a Potential Risk Factor of Hamstring Injury in Football

Effect of Advanced Footwear Technology Spikes on Sprint Acceleration: A Multiple N-of-1 Trial

BACKGROUND

In contrast with Advanced Footwear Technology-AFT running shoes for long-distance, little is known about AFT sprint spikes on performance and acceleration parameters. However, their use has become widespread since the Tokyo 2020 Olympics, and knowledge of their effects would seem to be an essential starting point before any clinical or socio-economic considerations.

OBJECTIVES

Our objectives were to determine intra- and inter-subject sprinting performance modifications with Nike® AFT spikes (NAS) compared to standard spiked-shoes (SS).

METHODS

Healthy regional to national sprint athletes (n = 21, ≥ 750 pts World Athletics) performed 16 repetitions of 30-m sprints with either the NAS or SS condition during a single session, based on the multiple N-of-1 method, with pairwise randomisation and double-blind procedure. Time on 30-m sprints (Stalker radar), force-velocity profile (F0, V0, Vmax, Pmax, RF, DRF and FVP slope), and confounding factors (wind and shoe mass) were measured. Statistical analyses included a mixed linear regression model for group analyses, and randomisation test inversion and non-overlap-of-all-pair (NAP) methods for intra-individual analysis.

RESULTS

NAS improved 30-m time by a mean of - 0.02 s (SMD = 0.4, p = 0.014), with no interaction with any confounding factors. Significant changes were seen in velocity (Vmax : SMD = 0.9, p < 0.001; V0: SMD = 0.7, p < 0.001) and the horizontal ratio of force (RFmax: SMD = 0.5, p = 0.043), with no changes observed in force production. Whatever the footwear, one unit of positive wind (+ 1 m.s- 1 ) improved performance by - 0.03 s (p < 0.001). At an individual level, four athletes improved (NAP ≥ 0.69), and one had a statistical decrease in performance. Changes in F-V profiles were largely individual.

CONCLUSIONS

A positive effect on sprint acceleration characteristics was observed when using Nike® AFT spikes, due to an increase in velocity and the horizontal ratio of force. A major variability in inter-individual response justifies single-case experimental designs for research on the topic.

TRIAL REGISTRATION NUMBER

NCT05881148.

Hamstring Injuries, From the Clinic to the Field: A Narrative Review Discussing Exercise Transfer

PURPOSE

The optimal approach to hamstring training is heavily debated. Eccentric exercises reduce injury risk; however, it is argued that these exercises transfer poorly to improved hamstring function during sprinting. Some argue that other exercises, such as isometric exercises, result in better transfer to running gait and should be used when training to improve performance and reduce injury risk. Given the performance requirements of the hamstrings during the terminal swing phase, where they are exposed to high strain, exercises should aim to improve the torque production during this phase. This should improve the hamstrings' ability to resist overlengthening consequently, improving performance and limiting strain injury. Most hamstring training studies fail to assess running kinematics postintervention. Of the limited evidence available, only eccentric exercises demonstrate changes in swing-phase kinematics following training. Studies of other exercise modalities investigate effects on markers of performance and injury risk but do not investigate changes in running kinematics.

CONCLUSIONS

Despite being inconsistent with principles of transfer, current evidence suggests that eccentric exercises result in transfer to swing-phase kinematics. Other exercise modalities may be effective, but the effect of these exercises on running kinematics is unknown.

Hamstrings on focus: Are 72 hours sufficient for recovery after a football (soccer) match? A multidisciplinary approach based on hamstring injury risk factors and histology

This study aimed to assess acute and residual changes in sprint-related hamstring injury (HSI) risk factors after a football (soccer) match, focusing on recovery within the commonly observed 72-h timeframe between elite football matches. We used a multifactorial approach within a football context, incorporating optical and ultrastructural microscopic analysis of BFlh (biceps femoris long head) muscle fibres, along with an examination of BFlh fibre composition. Changes in sprint performance-related factors and HSI modifiable risk factors were examined until 3 days after the match (MD +3) in 20 football players. BFlh biopsy specimens were obtained before and at MD +3 in 10 players. The findings indicated that at MD +3, sprint-related performance and HSI risk factors had not fully recovered, with notable increases in localized BFlh fibre disruptions. Interestingly, match load (both external and internal) did not correlate with changes in sprint performance or HSI risk factors nor with BFlh fibre disruption. Furthermore, our study revealed a balanced distribution of ATPase-based fibre types in BFlh, with type-II fibres associated with sprint performance. Overall, the results suggest that a 72-h recovery period may not be adequate for hamstring muscles in terms of both HSI risk factors and BFlh fibre structure following a football match.

Implementing Velocity-Based Training to Optimize Return to Sprint After Anterior Cruciate Ligament Reconstruction in Soccer Players: A Clinical Commentary

After anterior cruciate ligament reconstruction (ACLR), return to sprint is poorly documented in the literature. In soccer, return to sprint is an essential component of return to play and performance after ACLR. The characteristics of running in soccer are specific (velocity differences, nonlinear, intensity). It is important to address these particularities, such as curvilinear running, acceleration, deceleration, changes of direction, and variations in velocity, in the patient's rehabilitation program. Force, velocity, and acceleration capacities are key elements to sprint performance. Velocity-based training (VBT) has gained much interest in recent years and may have a role to play in optimizing return to play and return to sprint after ACLR. Force, velocity, and acceleration can be assessed using force-velocity-power and acceleration-speed profiles, which should inform rehabilitation. The purpose of this commentary is to describe a velocity-based return to sprint program which can be used during ACLR rehabilitation.

Traumatic muscle injury

Traumatic muscle injury represents a collection of skeletal muscle pathologies caused by trauma to the muscle tissue and is defined as damage to the muscle tissue that can result in a functional deficit. Traumatic muscle injury can affect people across the lifespan and can result from high stresses and strains to skeletal muscle tissue, often due to muscle activation while the muscle is lengthening, resulting in indirect and non-contact muscle injuries (strains or ruptures), or from external impact, resulting in direct muscle injuries (contusion or laceration). At a microscopic level, muscle fibres can repair focal damage but must be completely regenerated after full myofibre necrosis. The diagnosis of muscle injury is based on patient history and physical examination. Imaging may be indicated to eliminate differential diagnoses. The management of muscle injury has changed within the past 5 years from initial rest, immobilization and (over)protection to early activation and progressive loading using an active approach. One challenge of muscle injury management is that numerous medical treatment options, such as medications and injections, are often used or proposed to try to accelerate muscle recovery despite very limited efficacy evidence. Another challenge is the prevention of muscle injury owing to the multifactorial and complex nature of this injury.

Exercise-Induced Fatigue in Hamstring versus Quadriceps Muscles and Consequences on the Torque-Duration Relationship in Men

PURPOSE

The present study investigated the mechanisms of neuromuscular fatigue in quadriceps and hamstring muscles and its consequences on the torque-duration relationship.

METHODS

Twelve healthy men performed a 5-min all-out exercise (3-s contraction, 2-s relaxation) with either quadriceps or hamstring muscles on separate days. Central fatigue and peripheral fatigue were quantified via changes in pre- to postexercise voluntary activation (VA) and potentiated twitch (P Tw ) torque evoked by supramaximal electrical stimulation, respectively. Critical torque was determined as the mean torque of the last six contractions, whereas W ' was calculated as the torque impulse done above critical torque.

RESULTS

After exercise, maximal voluntary contraction (MVC) decreased to a greater magnitude ( P < 0.001) in quadriceps (-67% ± 9%) compared with hamstring (-51% ± 10%). ∆P Tw was also greater in quadriceps compared with hamstring (-69% ± 15% vs 55% ± 10%, P < 0.01), whereas central fatigue only developed in quadriceps (∆VA, -25% ± 28%). Hamstring demonstrated reduced critical torque compared with quadriceps (60 ± 12 vs 97 ± 26 N·m, P < 0.001) as well as drastically lower W ' (1001 ± 696 vs 8111 ± 2073 N·m·s, P < 0.001). No correlation was found between quadriceps and hamstring for any index of neuromuscular fatigue (∆MVC, ∆P Tw , or ∆VA).

CONCLUSIONS

These findings revealed that hamstring presented different etiology and magnitude of neuromuscular fatigue compared with quadriceps. The absence of correlation observed between quadriceps and hamstring fatigue parameters (∆MVC, ∆P Tw , or ∆VA) suggests no interrelation in fatigue etiology between these two muscle groups within individuals and, therefore, highlights the need to investigate specifically hamstring muscle fatigue.

A novel multifactorial hamstring screening protocol: association with hamstring muscle injuries in professional football (soccer) - a prospective cohort study

The aim of this pilot study was to analyze the potential association of a novel multifactorial hamstring screening protocol with the occurrence of hamstring muscle injuries (HMI) in professional football. 161 professional male football players participated in this study (age: 24.6 ± 5.36 years; body-height: 180 ± 7.07 cm; body-mass: 77.2 ± 7.70 kg). During the pre- and mid-season, players performed a screening protocol consisting of 11 tests aimed to evaluate their performance in regards to four main musculoskeletal categories: posterior chain strength, sprint mechanical output, lumbopelvic control and range of motion. Univariable cox regression analysis showed no significant association between the isolated test results and new HMI occurrence during the season (n = 17) (p > 0.05). When including injuries that took place between the pre- and mid-season screenings (~90 days), maximal theoretical horizontal force (F0) was significantly associated with higher HMI risk between pre- and mid-season evaluations (n = 14, hazard ratio; 4.02 (CI95% 1.08 to 15.0, p = 0.04). This study identified that 1) no single screening test was sufficient to identify players at risk of HMI within the entire season, while 2) low F0 was associated with increased risk of HMI when occurring closer to the moment of screening. The present results support the potential relevance of additionally including frequent F0 testing for HMI risk reduction management. Replication studies are needed in larger cohorts for more accurate interpretations on "univariable and multivariable levels levels. Finally, future studies should explore whether improving F0 is relevant within a multifactorial HMI risk reduction approach.

Hamstring Muscle Injuries and Hamstring Specific Training in Elite Athletics (Track and Field) Athletes

OBJECTIVE

We aimed to describe hamstring muscle injury (HMI) history and hamstring specific training (HST) in elite athletes. A secondary aim was to analyse the potential factors associated with in-championships HMI.

METHODS

We conducted a prospective cohort study to collect data before and during the 2018 European Athletics Championships. Injury and illness complaints during the month before the championship, HMI history during the entire career and the 2017-18 season, HST (strengthening, stretching, core stability, sprinting), and in-championship HMI were recorded. We calculated proportions of athletes with HMI history, we compared HST according to sex and disciplines with Chi2 tests or ANOVA, and analysed factors associated with in-championship HMI using simple model logistic regression.

RESULTS

Among the 357 included athletes, 48% reported at least one HMI during their career and 24% during the 2017-18 season. Of this latter group, 30.6% reported reduced or no participation in athletics' training or competition at the start of the championship due to the hamstring injury. For HST, higher volumes of hamstring stretching and sprinting were reported for disciplines requiring higher running velocities (i.e., sprints, hurdles, jumps, combined events and middle distances). Five in-championship HMIs were recorded. The simple model analysis showed a lower risk of sustaining an in-championships HMI for athletes who performed more core (lumbo-pelvic) stability training (OR = 0.49 (95% CI: 0.25 to 0.89), p = 0.021).

CONCLUSIONS

Our present study reports that HMI is a characteristic of the athletics athletes' career, especially in disciplines involving sprinting. In these disciplines, athletes were performing higher volumes of hamstring stretching and sprinting than in other disciplines. Further studies should be conducted to better understand if and how HST are protective approaches for HMI in order to improve HMI risk reduction strategies.

The Association Between Force-Velocity Relationship in Countermovement Jump and Sprint With Approach Jump, Linear Acceleration and Change of Direction Ability in Volleyball Players

The force-velocity (FV) relationship allows the identification of the mechanical capabilities of musculoskeletal system to produce force, power and velocity. The aim of this study was to assess the associations of the mechanical variables derived from the FV relationship with approach jump, linear sprint and change of direction (CoD) ability in young male volleyball players. Thirty-seven participants performed countermovement jumps with incremental loads from bodyweight to 50–100 kg (depending on the individual capabilities), 25-m sprint with split times being recorded for the purpose of FV relationship calculation, two CoD tests (505 test and modified T-test) and approach jump. Results in this study show that approach jump performance seems to be influenced by maximal power output (r = 0.53) and horizontal force production (r = 0.51) in sprinting, as well as force capacity in jumping (r = 0.45). Only the FV variables obtained from sprinting alone contributed to explaining linear sprinting and CoD ability (r = 0.35–0.93). An interesting finding is that sprinting FV variables have similar and some even stronger correlation with approach jump performance than jumping FV variables, which needs to be considered for volleyball training optimization. Based on the results of this study it seems that parameters that refer to horizontal movement capacity are important for volleyball athletic performance. Further interventional studies are needed to check how to implement specific FV-profile-based training programs to improve specific mechanical capabilities that determine volleyball athletic performance and influence the specific physical performance of volleyball players.

Sprinting Biomechanics and Hamstring Injuries: Is There a Link? A Literature Review

Hamstring strain injury (HSI) is a common and costly injury in many sports such as the various professional football codes. Most HSIs have been reported to occur during high intensity sprinting actions. This observation has led to the suggestion that a link between sprinting biomechanics and HSIs may exist. The aim of this literature review was to evaluate the available scientific evidence underpinning the potential link between sprinting biomechanics and HSIs. A structured search of the literature was completed followed by a risk of bias assessment. A total of eighteen studies were retrieved. Sixteen studies involved retrospective and/or prospective analyses, of which only three were judged to have a low risk of bias. Two other case studies captured data before and after an acute HSI. A range of biomechanical variables have been measured, including ground reaction forces, trunk and lower-limb joint angles, hip and knee joint moments and powers, hamstring muscle–tendon unit stretch, and surface electromyographic activity from various trunk and thigh muscles. Overall, current evidence was unable to provide a clear and nonconflicting perspective on the potential link between sprinting biomechanics and HSIs. Nevertheless, some interesting findings were revealed, which hopefully will stimulate future research on this topic.