High-Intensity Conditioning Activity Causes Localized Postactivation Performance Enhancement and Nonlocalized Performance Reduction

ABSTRACT

Kolinger D, Stastny P, Pisz A, Krzysztofik M, Wilk M, Tsoukos A, and Bogdanis GC. High-intensity conditioning activity causes localized postactivation performance enhancement and nonlocalized performance reduction. J Strength Cond Res 38(1): e1-e7, 2024-This study aimed to examine whether a conditioning activity (CA) performed by the legs (barbell back squat) may cause postactivation performance enhancement (PAPE) on muscle groups other than leg extensors in isokinetic (eccentric [ECC] and concentric [CON]) and dynamic movement. Twelve male basketball players (age: 21.3 ± 3.2, body mass: 89.6 ± 14.1 kg, height: 187.4 ± 4.6 cm, and 1 repetition maximum (1RM) barbell back squat: 113 ± 21 kg) with previous resistance-training experience of at least 2 years, performed 3 sets of 3-4 repetitions of back-squats with submaximal load (60, 90, and 90% 1RM) as CA. Before and after the CA, they performed pretest and post-test in the form of countermovement jumps (CMJs) (localized) or explosive push-ups (EPUs) (nonlocalized) along with isokinetic flexion and extension at the knee (localized) or at the elbow (nonlocalized). The localized and nonlocalized protocols were divided into 2 days in a randomized order. The back squat as CA significantly increased peak torque (PT) (p < 0.05) in all CON and ECC muscle actions and average power per repetition (APPR) (p < 0.05) (all muscle actions except ECC flexion) of the localized isokinetic tests with large (>0.8) and medium (0.4-0.79) effect sizes and significantly decreased (p < 0.01) the PT and APPR (p < 0.01) of the nonlocalized isokinetic test in the ECC flexion. The CMJ and EPU tests showed no significant differences (p > 0.05) between premeasures and postmeasures of take-off height. The effect of PAPE seems to be specific to the muscles most involved in the CA, and the CA inhibits PT of subsequent muscle ECC contractions in muscles not involved in the CA.

Role of gluteus maximus and medius activation in the lower limb biomechanical control during functional single-leg Tasks: A systematic review

OBJECTIVES

Single-leg (SL) tasks are included as assessment and intervention strategies in several dysfunctions due to the inherent motor control requirement. The recruitment of gluteus maximus (GMAX) and medius (GMED) muscles is essential for proper biomechanical control of the knee and hip joints. The study aims to identify the role of gluteal activation in the biomechanical control of the lower limb during SL tasks.

METHODS

This is a systematic review with searches performed in Pubmed, CINAHL, MEDLINE, Web of Science, and Sportdiscus databases. Cross-sectional studies carried out with asymptomatic individuals were selected, containing hip and knee kinematic and kinetic outcomes assessed through 3D or 2D movement analysis and EMG activity of GMED and GMAX muscles. Two independent reviewers performed the procedures to select the studies, determine the methodological quality and extract the data.

RESULTS

The initial search resulted in 391 studies, and after the assessment procedures, 11 studies were included. Lower GMAX activation was associated with greater hip internal rotation (HIR) excursion and greater HIR moment, and lower GMED activation was associated with greater hip adduction (HAD)/knee abduction (KAB) excursions and greater KAB moment during single-leg squat (SLS).

CONCLUSIONS

The SL tasks showed a relevant association between the gluteal EMG and other biomechanical outcomes, mainly the SLS task. Interpretation must be cautious, as most studies present high and moderate methodological quality, especially on kinetic data.

What are gender differences in lower limb muscle activity during jump-landing tasks? A systematic review and meta-analysis

Background

Gender differences in muscle activity during landing have been proposed as a possible contributing factor to the greater incidence of anterior cruciate ligament injuries in women. Conflicting results among a few studies in this regard makes it impossible to reach correct conclusions.

Objectives

The aim of this study was systematic review and the meta-analysis of previous studies which have compared the electromyographic activity of lower limb muscles in gluteus muscles (maximus and medius), quadriceps (rectus femoris, vastus medialis and lateralis), hamstrings (biceps femoris and semimembranosus), and gastrocnemius in men and women in jump–landing task.

Methods

A systematic search of the PubMed, SCOPUS, Science Direct databases was performed for eligible articles in October 2020. Cross-sectional studies that compared the muscle activity of male and female athletes without a history of previous injury in the jump–landing task were included. Unisex and non-athlete's studies were extracted from the included studies. The data were synthesized using a fixed and random effects model.

Results

Eight studies involving 145 participants were included. All participants were people who participated in regular exercises. The meta-analysis of timing and muscle activity was performed in the feedforward (pre contact) and feedback (post contact) stages. There were no significant differences in the muscle activity of biceps femoris (MD = −12.01; 95% CI − 51.49 to 27.47; p = 0.55; I² = 87%), vastus medialis (MD = −53.46; 95% CI − 129.73 to 22.81; p = 0.17; I² = 91%), semimembranosus (MD = 1.81; 95% CI − 6.44 to 10.07; p = 0.67; I² = 0%), gluteus medius (MD = −3.14; 95% CI − 14.24 to 7.96; p = 0.58; I² = 48%), and rectus femoris (MD = −5.83; 95% CI − 14.57 to 2.92; p = 0.19; I² = 87%) in the pre contact phase between two sexes. There was a significant difference between men and women in the activity of vastus lateralis muscle in the post contact phase (MD = −34.90; 95% CI − 48.23 to − 21.57). No significant difference was observed between the men and women in the timing of semimembranosus (MD = 23.53; 95% CI − 14.49 to 61.54; p = 0.23; I² = 56%) and biceps femoris muscle activity (MD = −46.84; 95% CI − 97.50 to 3.83; p = 0.07; I² = 82%).

Conclusion

The results showed that in all lower limb muscles except vastus lateralis there were no significant differences between muscle activity and muscle contraction timing in both sexes before and after foot contact. Therefore, it can be concluded that the reason for the greater susceptibility of ACL injuries in women than men is maybe related to other factors such as biomechanical and hormonal. Additional good quality research in this regard is required to strengthen these conclusions.

Sex differences in muscle activation patterns associated with anterior cruciate ligament injury during landing and cutting tasks: A systematic review

Neuromuscular control is critical for maintaining dynamic joint stability and mitigating the risk of anterior cruciate ligament (ACL) injury. Given the increased risk of ACL injury in females, sex-based differential muscle activation strategies are often associated with this risk. For example, the quadriceps-dominant muscle activation strategy sometimes observed in females has been discussed as a cause of their increased risk of ACL injury. However, there has been no synthesised knowledge on sex differences in muscle activation patterns associated with ACL injuries. Therefore, the purpose of this review was to synthesise sex differences in muscle activation patterns in movements associated with ACL injuries in both adult and adolescent populations. A systematic electronic database search was conducted. Thirty studies were included in the review. Females demonstrated higher pre- and post-landing activation of the quadriceps and lower activation of the hamstrings in 15 studies. Females also had higher quadriceps-to-hamstring co-contraction ratios during pre- and post-landing phases compared to their male counterparts in 4 of 9 studies that considered co-contraction. While some studies supported the quadriceps-dominant activation strategies in females, no consensus can be drawn due to methodological inconsistencies and limitations. Also, despite the importance of ACL injury prevention in children and adolescents, the evidence on sex difference in muscle activation patterns in this population is insufficient to draw meaningful conclusions.

What is normal? Female lower limb kinematic profiles during athletic tasks used to examine anterior cruciate ligament injury risk: a systematic review

BACKGROUND

It has been proposed that the performance of athletic tasks where normal motion is exceeded has the potential to damage the anterior cruciate ligament (ACL). Determining the expected or 'normal' kinematic profile of athletic tasks commonly used to assess ACL injury risk can provide an evidence base for the identification of abnormal or anomalous task performances in a laboratory setting.

OBJECTIVE

The objective was to conduct a systematic review of studies examining lower limb kinematics of females during drop landing, drop vertical jump, and side-step cutting tasks, to determine 'normal' ranges for hip and knee joint kinematic variables.

DATA SOURCES

An electronic database search was conducted on the SPORTDiscus(TM), MEDLINE, AMED and CINAHL (January 1980-August 2013) databases using a combination of relevant keywords.

STUDY SELECTION

Studies identified as potentially relevant were independently examined by two reviewers for inclusion. Where consensus could not be reached, a third reviewer was consulted. Original research articles that examined three-dimensional hip and knee kinematics of female subjects during the athletic tasks of interest were included for review. Articles were excluded if subjects had a history of lower back or lower limb joint injury or isolated data from the female cohort could not be extracted.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two reviewers independently assessed the quality of included studies. Data on subject characteristics, the athletic task performed, and kinematic data were extracted from included studies. Studies were categorised according to the athletic task being examined and each study allocated a weight within categories based on the number of subjects assessed. Extracted data were used to calculate the weighted means and standard deviations for hip and knee kinematics (initial contact and peak values). 'Normal' motion was classified as the weighted mean plus/minus one standard deviation.

RESULTS

Of 2,920 citations, a total of 159 articles were identified as potentially relevant, with 29 meeting all inclusion/exclusion criteria. Due to the limited number of studies available examining double-leg drop landings and single-leg drop vertical jumps, insufficient data was available to include these tasks in the review. Therefore, a total of 25 articles were included. From the included studies, 'normal' ranges were calculated for the kinematic variables of interest across the athletic tasks examined.

LIMITATIONS

Joint forces and other additional elements play a role in ACL injuries, therefore, focusing solely on lower limb kinematics in classifying injury risk may not encapsulate all relevant factors. Insufficient data resulted in no normal ranges being calculated for double-leg drop land and single-leg drop vertical jump tasks. No included study examined hip internal/external rotation during single-leg drop landings, therefore ranges for this kinematic variable could not be determined. Variation in data between studies resulted in wide normal ranges being observed across certain kinematic variables.

CONCLUSIONS

The ranges calculated in this review provide evidence-based values that can be used to identify abnormal or anomalous athletic task performances on a multi-planar scale. This may be useful in identifying neuromuscular factors or specific muscular recruitment strategies that contribute to ACL injury risk.

Prevenção de lesões do ligamento cruzado anterior em futebolistas

A lesão do joelho é a mais comum entre as lesões graves apresentadas por futebolistas, destacando-se o ligamento cruzado anterior como um dos ligamentos do joelho mais frequentemente lesados. Assim, a prevenção de lesões do ligamento cruzado anterior em futebolistas deve ser encarada como uma preocupação constante para todos os agentes ligados à modalidade, independentemente do nível competitivo, idade e sexo dos praticantes. OBJETIVOS: O objetivo deste trabalho é a análise da importância do trabalho de prevenção de lesões do LCA em futebolistas que possa ser incorporado no treino de futebol. METODOLOGIA: A metodologia utilizada neste trabalho foi uma revisão da literatura. CONCLUSÕES: Propõe-se um programa de prevenção de lesões do ligamento cruzado anterior em futebolistas, com três sessões de treino semanais, englobando treino neuromuscular e treino proprioceptivo.

Evaluation of plyometric intensity using electromyography

The purpose of this study was to investigate the motor unit activation of the quadriceps (Q), hamstring (H), and gastrocnemius (G) muscle groups during a variety of plyometric exercises to further understand the nature of these exercises. Twenty-three athletes volunteered to perform randomly ordered plyometric exercises, thought to cover a continuum of intensity levels, including two-foot ankle hops; 15-cm cone hops; tuck, pike, and box jumps; one- and two-leg vertical jump and reach; squat jumps with approximately 30% of their 1RM squat load; and 30- and 61-cm depth jumps. Integrated electromyographic data were analyzed for each exercise using a one-way repeated-measures ANOVA. Results revealed significant main effects for the Q when all subjects are analyzed, as well as for separate analysis of men, women, subjects with vertical jumps greater than 50 cm, and those with vertical jumps less than or equal to 50 cm (p < or = 0.05). Significant main effects were also found for the G muscle group in the analysis of all subjects, as well as for men and subjects with vertical jumps greater than 50 cm (p < or = 0.05). No significant main effects were found for the H muscle group. Pairwise comparisons revealed a variety of differences among plyometric exercises. In some cases, plyometrics previously reported to be of high intensity, such as the depth jump, yielded relatively little motor unit recruitment compared with exercises typically thought to be of low intensity. Results can assist the practitioner in creating plyometric programs based on the nature of the motor unit recruitment.

Gender differences in gluteus medius muscle activity exist in soccer players performing a forward jump

The purpose of this study was to evaluate gender differences in muscle activity while landing from a forward jump. Eight male and 8 female division-one varsity soccer athletes participated in this study. Subjects performed five trials of a 100 cm forward jump single leg landing. Surface electromyography (EMG) was collected at the gluteus medius, vastus lateralis, lateral hamstring, and medial gastrocnemius. Data were interpreted by VICON workstation and analyzed with Acknowledge software. Average root mean square of 200 ms following initial heel contact from landing were normalized to static one-leg stance and used in data analysis. A fixed-effect multivariate analysis of variance showed average gluteus medius activity was significantly higher in males (7.16 +/- 3.16) than in females (2.62 +/- 0.95). There were no differences between genders for any of the other muscles collected. Gender-specific neuromuscular strategies used to attenuate the forces of landing may involve more gluteus medius muscle activity in males than in females.