Contribution of trunk muscularity on sprint run

Effects of Eight-Week Circuit Training with Core Exercises on Performance in Adult Male Soccer Players

Core exercises have been widely promoted in the last 25 years. However, the scientific debate about its efficacy for improving individual and team sports performance is still open. Thus, the present study aims to investigate the effects of circuit training with a core exercise program on physical performance in competitive amateur soccer players. The training was conducted during the off-season period, two times per week for 8 weeks. Pre- and post-evaluations were conducted using the following tests: Y-Balance Test (YB), standing long jump (SLJ), medicine ball chest press (MBC), curl-up (CU), and Illinois Agility Test (IAT). A total of 19 adults were divided into an experimental group (EG, n = 11, age 22 years, weight 71.2 ± 4.8 kg, height 174 ± 5.8 cm) and a control group (CG, n = 8, age 22 years, weight 73.2 ± 4.1 Kg, height 176 ± 6.3 cm). The EG showed significant improvements in lower and upper body strength, core endurance and balance, whereas the CG did not report significant changes in the pre- and post-test comparison. Despite study limitations, our positive results show that circuit training with core exercises appears to be a good strategy for performance improvement in adult soccer players.

Variation in human 3D trunk shape and its functional implications in hominin evolution

This study investigates the contribution of external trunk morphology and posture to running performance in an evolutionary framework. It has been proposed that the evolution from primitive to derived features of torso shape involved changes from a mediolaterally wider into a narrower, and antero-posteriorly deeper into a shallower, more lightly built external trunk configuration, possibly in relation to habitat-related changes in locomotor and running behaviour. In this context we produced experimental data to address the hypothesis that medio-laterally narrow and antero-posteriorly shallow torso morphologies favour endurance running capacities. We used 3D geometric morphometrics to relate external 3D trunk shape of trained, young male volunteers (N = 27) to variation in running velocities during different workloads determined at 45–50%, 70% and 85% of heart rate reserve (HRR) and maximum velocity. Below 85% HRR no relationship existed between torso shape and running velocity. However, at 85% HRR and, more clearly, at maximum velocity, we found highly statistically significant relations between external torso shape and running performance. Among all trained subjects those with a relatively narrow, flat torso, a small thoracic kyphosis and a more pronounced lumbar lordosis achieved significantly higher running velocities. These results support the hypothesis that external trunk morphology relates to running performance. Low thoracic kyphosis with a flatter ribcage may affect positively respiratory biomechanics, while increased lordosis affects trunk posture and may be beneficial for lower limb biomechanics related to leg return. Assuming that running workload at 45–50% HRR occurs within aerobic metabolism, our results may imply that external torso shape is unrelated to the evolution of endurance running performance.

Relationship between thigh muscle cross-sectional areas and single leg stand-up test in Japanese older women

In older adults, the quantitative decline of the quadriceps femoris is associated with the augmentation of difficulty in the execution of a stand-up task. However, it is unclear whether the cross-sectional areas (CSAs) of individual thigh muscles differ between older adults who can stand up from a 40-cm-height chair on a single leg and those who cannot. To investigate this, the present study determined the CSAs of individual mid-thigh muscles in 67 Japanese women aged 60–77 years by using a magnetic resonance imaging method. Participants were asked to stand up from a 40-cm-height chair on a single leg, and those who could and could not stand up without leaning back and maintain a standing posture for 3 seconds on a single leg were allocated into the successful group (SG, n = 40) and unsuccessful group (USG, n = 27), respectively. Only the CSA of the adductors (sum of the adductor longus and adductor magnus) was significantly smaller in USG compared to SG. When CSA was expressed relative to the two-third power of body mass, the values for the four heads of the quadriceps femoris and biceps femoris long head, as well as the adductors, were significantly lower in USG than in SG. The current results indicate that in terms of the value relative to body mass, the reduced CSAs of the adductors and biceps femoris long head, as well as the four heads of the quadriceps femoris, are associated with the failure of attempts to stand up from a 40-cm-height chair on a single leg in older women. This may be due to the anatomical function of the two muscle groups, which contributes to hip extension movement involved in transitioning from a sitting position to a standing position during the stand-up task.

Acute Leg and Trunk Muscle Fatigue Differentially Affect Strength, Sprint, Agility, and Balance in Young Adults

ABSTRACT

Roth, R, Donath, L, Zahner, L, and Faude, O. Acute leg and trunk muscle fatigue differentially affect strength, sprint, agility, and balance in young adults. J Strength Cond Res 35(8): 2158-2164, 2021-How important leg or trunk muscles are for balance and sprint performance is still unexplored. Therefore, we separately fatigued the leg and trunk musculature and examined their contribution to strength, balance, sprint, and agility performance. Twenty-four healthy adults (12 women; age 22.9 [SD: 2.6] years; body mass 59 [10] kg; height 1.65 [0.09] m; and 12 men; age 22.7 [3.0] years; body mass 78 [9] kg; height 1.81 [0.06] m; at least 3 training sessions/week for at least 90 minutes) underwent a leg and a trunk fatigue procedure, each of 20-minute duration and a control condition at rest in a randomized order. Each condition was conducted individually on 3 separate days. Isokinetic leg and trunk strength, as well as static and dynamic balance, sprint, agility, and prone plank endurance, were assessed before and after each fatiguing protocol. Before assessment, a familiarization was conducted. Pairwise magnitude-based inference analyses showed likely relevant deterioration in leg (probability >87%; 0.36 < standardized mean differences [SMDs] < 0.92) and trunk (>88%, 0.28 < SMD < 0.74) fatigue procedures for all motor test parameters compared with the control condition, except for the 20-m sprint after the trunk fatigue procedure. Isokinetic strength testing revealed a large loss of strength in leg fatigue (particularly knee extension, 78%, SMD = 0.24) and trunk fatigue (trunk flexion, 100%, SMD = 1.36). Acute fatigue of leg and trunk muscles decreases performance in relevant measures of strength, balance, sprint, and agility. The impact of leg fatigue compared with trunk fatigue was larger in almost all measurements.

Hamstring Muscle Volume as an Indicator of Sprint Performance

ABSTRACT

Nuell, S, Illera-Domínguez, V, Carmona, G, Macadam, P, Lloret, M, Padullés, JM, Alomar, X, and Cadefau, JA. Hamstring muscle volume as an indicator of sprint performance. J Strength Cond Res 35(4): 902-909, 2021-This study aimed to compare mechanical properties and performance during sprinting, as well as thigh muscle volumes (MVs), between national-level sprinters and physically active males. In addition, the relationships between thigh MVs and sprint mechanical properties and performance were investigated. Seven male sprinters and 9 actives performed maximal-effort 40-m sprints. Instantaneous velocity was measured by radar to obtain theoretical maximum force (F0), the theoretical maximum velocity (V0), and the maximum power (Pmax). For MV assessment, series of cross-sectional images of each subject's thigh were obtained by magnetic resonance imaging for each of the quadriceps and hamstring muscles and the adductor muscle group. Sprinters were faster over 10 m (7%, effect size [ES] = 2.12, p < 0.01) and 40 m (11%, ES = 3.68, p < 0.01), with significantly higher V0 (20%, ES = 4.53, p < 0.01) and Pmax (28%, ES = 3.04, p < 0.01). Sprinters had larger quadriceps (14%, ES = 1.12, p < 0.05), adductors (23%, ES = 1.33, p < 0.05), and hamstrings (32%, ES = 2.11, p < 0.01) MVs than actives. Hamstrings MV correlated strongly with 40-m sprint time (r = -0.670, p < 0.01) and V0 (r = 0.757, p < 0.01), and moderately with Pmax (r = 0.559, p < 0.05). Sprinters were significantly faster and had greater V0 and Pmax than active males. Larger MVs were found in sprinters' thighs, especially in the hamstring musculature, and strong correlations were found between hamstring MV and sprint mechanical properties and sprint performance.

The Relationship between Core Strength Performance with Sprint Acceleration

The objectives of this study were to determine the relationship between average core strength and sprint acceleration performance. Besides that, this study also intended to determine the relationship between body height and body weight with average core strength and sprint acceleration performance. Sixty-three male sport science students (height 1.67 ± 0.07 m; body mass 63.25 ± 13.90 kg) from variety of sport background participated in this study. To test the relationship, core strength (7-stage abdominal strength test and prone-bridge test) and sprint acceleration (35-m sprint test) performance was measured and a Pearson’s correlation coefficient was used to analyse the results. Sprint was found to be significantly correlated with prone bridge performance, r (63) = -0.43, p = 0.00). The relationship between body height with sprint performance stated significant relationship (r (63) = -0.48, p = 0.00) and body weight with 7-stage abdominal strength values reveal a significant relationship (r (63) = - 0.28, p = 0.03). In conclusion, this finding has suggested an optimum core strength may influences sprint acceleration performance which would give greater advantages in order to improve physical performance or optimize sport performance.

The determination of the cross-sectional area of the lumbar erector spinae muscles of Olympic style weightlifting athletes by using MRI

OBJECTIVE

The study aims to measure the cross-sectional area of the lumbar erector spinae muscles from L3-L4 intervertebral disc levels by using magnetic resonance images of Olympic style weightlifting athletes (male n= 15, female n= 15) and sedentary individuals (male n= 15, female n= 15).

METHODS

A 1.5 Tesla device was used for the magnetic resonance imaging process of all participants. The images were then executed in ImageJ software and the cross-sectional area was measured after the required synchronization steps were conducted.

RESULTS

On the images taken from L3-L4 intervertebral disc levels, we observed that right-left cross-sectional area measurements of erector spinae muscles of sedentary males and females in the control groups were smaller than those of male and female athletes in Olympic style weightlifting. We also found a symmetry between right-left cross-sectional area measurements of groups of athletes.

CONCLUSIONS

From the study findings, we might conclude that trainings of Olympic style weightlifting possess a hypertrophic effect on the cross-sectional area of erector spinae muscles of Olympic style weightlifting athletes.

Effects of pelvic and core strength training on biomechanical risk factors for anterior cruciate ligament injuries

BACKGROUND

Little is known about the changes in biomechanical risk factors for an anterior cruciate ligament (ACL) injury after participation in a pelvic and core strength training (PCST) program in female team players.

METHODS

This is a randomized controlled trial for which a total of 29 female soccer players were recruited from a soccer club and split into two groups, namely, experimental group (EG, N.=18; mean [SD] age, 17.8 [2.0 years], weight 64.0 [6.6] kg and height 1.7 [0.0] m) and control group (control, N.=11; mean [SD] age, 16.2 [1.2] years, weight 61.6 [7.3] kg and height 1.7 [0.0] m). The EG participated in an in-season 8-week PCST program (twice/week). Participants in the CG performed their normal training without additional pelvic and core strengthening. Pre- and postintervention knee frontal plane projection angle (FPPA), hip, knee and ankle peak flexion angles and jump height were collected during bilateral and unilateral drop jumps.

RESULTS

PCST significantly reduced FPPA at dynamic landing, in both dominant (-7.1º) and non-dominant lower extremities (-8º). Further, this training significantly increased the peak hip (24.4º) and knee flexion angles (14.94º), but not the peak ankle dorsiflexion angle (P>0.05) which, significantly decreased in the CG (-3.5º). Following the intervention, EG significantly increased measures obtained for both bilateral (2.84 cm) and unilateral jumps (1.33 cm for the dominant leg and 1.22 cm for the non-dominant leg) (P<0.05), not so for CG (P<0.05).

CONCLUSIONS

PCST resulted in improvements on ACL injury risk factors and vertical drop jump performance, suggesting that strengthening this body part warrants not only injury prevention, but increases jumping performance.

Core Endurance Relationships With Athletic and Functional Performance in Inactive People

Research regarding the relationship between core muscle endurance and performance is limited. The purpose of this study was to analyze the association between core/trunk endurance and athletic performance. Seventy-four healthy participants between 18 and 45 years old participated in this study (Age: 26.0 ± 6.5 years; Mass: 74.6 ± 12.8 kg; Height: 1.74 ± 0.08 m; BMI: 19.0 ± 6.8 kg/m²). The core endurance was measured using the McGill protocol, consisting of the following tests: trunk flexion, back extension, and side-bridge. Functional performance was evaluated with push-ups, sit to stand, T-run test, countermovement jump (CMJ), Yo-Yo test, maximum dynamic strength-one repetition maximum (1RM) and muscle power on the bench press, pull row, and leg press. The regression results between the McGill protocol (proxy for core/trunk endurance) and the dependent variables were: 1RM pull row: r² = 0.109 with p = 0.046; RM bench press: r² = 0.149 with p = 0.012; RM leg press: r² = 0.144 with p = 0.013 and power pull row: r² = 0.151 with p = 0.016; power bench press: r² = 0.136 with p = 0.026; power leg press: r² = 0.122 with p = 0.013), push-ups: r² = 0.157 with p < 0.001, sit to stand: r² = 0.198 with p < 0,001), functional movement score: r² = 0.209 with p < 0.001). Nevertheless, core endurance scores were not able to predict jump ability (r² = 0.014, p = 0.807) or agility (T-test: 0.036 with p = 0.497). In conclusion, core endurance exerted no significant influence the agility and jump performance but influenced the ability to run intermittently, exert maximum power and strength in different actions (push, pull, and lift exercises) related to the better quality of movement (FMS).

A 100-m Sprint Time Is Associated With Deep Trunk Muscle Thickness in Collegiate Male Sprinters

Introduction: One reason athletes train their trunk muscles is that the body's trunk stability has been shown to prevent injury. However, the relationship between body trunk muscle thickness, particularly that of deep muscles, and athletic performance remains to be clarified.

Purpose: We aimed to explore the relationship between 100-m sprint performance and the sizes of the trunk stabilizing muscles, the psoas major muscle (PM), transversus abdominis (TA), and multifidus muscle (MM), in collegiate sprinters.

Methods: Fourteen male sprinters belonging to a university athletics club participated in this study. The thicknesses of the TA and MM were measured using an ultrasonic diagnostic apparatus (ProSound C3; Aloka, Tokyo, Japan). The cross-sectional area of the PM was assessed by a magnetic resonance imaging apparatus (Vantage Elan; Toshiba Medical Systems, Tokyo, Japan). The relationship between these anthropometric parameters and the 100-m sprint time was analyzed by Spearman's correlation coefficient, multi- regression analysis, and the change-point regression model.

Results: The sizes (mean ± SD) of the muscles were: PM, 43.074 ± 7.35 cm²; TA, 4.36 ± 0.72 mm; and MM, 3.99 ± 0.48 cm. The mean 100-m sprint time was 11.00 ± 0.48 s. Spearman's correlation analysis revealed that the 100-m sprint time had a significant moderate negative correlation with TA (ρ = −0.691, p < 0.01) and a low negative but not significant correlation with MM (ρ = −0.327, p = 0.28), whereas PM did not show a significant or in-negligible correlation. The change-point regression model found the change-points in the 100-m sprint time and the thickness of the TA and MM at 4.70 mm (95% CI: 4.00–5.43 mm) and 3.84 cm (95% CI: 3.28–4.31 cm), respectively. The sprint time decreased with an increase in the thickness of the muscles up to the change-points, whereas it did not change even if the muscles became thicker than the change-points. The change-points were consistently observed when the thickness of the muscles was normalized by body mass.

Conclusion: Sprint performance for 100-m was found to be associated with TA and MM thickness in a biphasic manner. As muscle thickness increased, the sprint time decreased, followed by a plateau phase.

The effects of a 4-week mesocycle of barbell back squat or barbell hip thrust strength training upon isolated lumbar extension strength

Objectives

Common exercises such as the barbell back squat (BBS) and barbell hip thrust (BHT) are perceived to provide a training stimulus to the lumbar extensors. However, to date there have been no empirical studies considering changes in lumbar extension strength as a result of BBS or BHT resistance training (RT) interventions.

Purpose

To consider the effects of BBS and BHT RT programmes upon isolated lumbar extension (ILEX) strength.

Methods

Trained male subjects (n = 14; 22.07 ± 0.62 years; 179.31 ± 6.96 cm; 79.77 ± 13.81 kg) were randomised in to either BBS (n = 7) or BHT (n = 7) groups and performed two training sessions per week during a 4-week mesocycle using 80% of their 1RM. All subjects were tested pre- and post-intervention for BBS and BHT 1RM as well as isometric ILEX strength.

Results

Analyses revealed that both BBS and BHT groups significantly improved both their BBS and BHT 1RM, suggesting a degree of transferability. However, the BBS group improved their BBS 1RM to a greater degree than the BHT group (p = 0.050; ∼11.8 kg/10.2% vs. ∼8.6 kg/7.7%, respectively). And the BHT group improved their BHT 1RM to a greater degree than the BBS group (p = 0.034; ∼27.5 kg/24.8% vs. ∼20.3 kg/13.3%, respectively). Neither BBS nor BHT groups significantly improved their isometric ILEX strength.

Conclusions

The present study supports the concept of specificity, particularly in relation to the movement mechanics between trunk extension (including pelvic rotation) and ILEX. Our data suggest that strength coaches, personal trainers, and trainees can self-select multi-joint lower-body trunk extension exercises based on preference or variety. However, evidence suggests that neither the BBS nor BHT exercises can meaningfully increase ILEX strength. Since strengthening these muscles might enhance physical and sporting performance we encourage strength coaches and personal trainers to prescribe ILEX exercise.

Associations Between Individual Lower-Limb Muscle Volumes and 100-m Sprint Time in Male Sprinters

PURPOSE

To elucidate the relationship between the muscularity of individual lower-limb muscles and 100-m-race time (t₁₀₀) in young-adult male sprinters.

METHODS

Thirty-one young-adult male sprinters took part in this study (age 19.9 ± 1.4 y, height 173.5 ± 4.6 cm, body mass 67.0 ± 4.9 kg, t₁₀₀ 10.23-11.71 s). Cross-sectional images from the origin to insertion of 12 lower-limb muscles were obtained with via magnetic resonance imaging (MRI). The absolute volume of each muscle, the ratio of total volume of measured muscles to body mass, the ratio of individual muscle volume to body mass, and the ratio between 2 individual muscle volumes were calculated as indices of muscularity using the images. A stepwise multiple-regression analysis was performed to examine the association between the indices and t₁₀₀.

RESULTS

A stepwise multiple-regression analysis produced an equation (adjusted R² = .234) with the gluteus maximus-to-quadriceps femoris muscle-volume ratio (β = -0.509, P = .003) as the explanatory variable.

CONCLUSIONS

Individual differences in 100-m-race performance cannot be explained by the muscularity of specific muscles, and 23% of the variability in the performance can be explained by the relative difference between the muscularity of gluteus maximus and quadriceps femoris; faster runners have a greater gluteus maximus relative to quadriceps femoris.

Hip Flexor and Knee Extensor Muscularity Are Associated With Sprint Performance in Sprint-Trained Preadolescent Boys

PURPOSE

We attempted to determine the relationships between the cross-sectional area (CSA) of the trunk and lower limb muscles and sprint performance in male preadolescent sprinters.

METHODS

Fifteen sprint-trained preadolescent boys (age 11.6 ± 0.4 y) participated in this study. The CSAs of the participants' trunk and lower limb muscles were measured using magnetic resonance imaging, and these muscles were normalized with free-fat mass. To assess participants' sprint performance, sprint time and variables during the 50-m sprint test were measured. The sprint variables were expressed as their indices by normalizing with body height.

RESULTS

The relative CSAs of psoas major, adductors, and quadriceps femoris were significantly correlated with sprint time (r = -.802, -.643, and -.639). Moreover, the relative CSAs of these muscles were significantly correlated with indices of sprint velocity (r = .694, .612, and .630) and step frequency (r = .687, .740, and .590) but not with that of step length.

CONCLUSIONS

These findings suggest that greater hip flexor and knee extensor muscularity in male preadolescent sprinters may help achieve superior sprint performance by potentially enhancing their moments, which may be induced by increased step frequency rather than step length during sprinting.

Applicability of ultrasonography for evaluating trunk muscles size in athletes: a study focused on baseball batters

[Purpose] Recently, we demonstrated that the thicknesses of trunk muscles measured using ultrasonography were correlated strongly with the cross-sectional areas measured using magnetic resonance imaging in untrained subjects. To further explore the applicability of ultrasonography in the clinical setting, the present study examined the correlation between ultrasonography-measured thicknesses and magnetic resonance imaging-measured cross-sectional areas of trunk muscles in athletes with trained trunk muscles. [Subjects and Methods] The thicknesses and cross-sectional areas at total 10 sites of the bilateral sides of the upper, central, and lower parts of the rectus abdominis, abdominal wall, and multifidus lumborum in 30 male baseball batters were measured. [Results] Overall thicknesses and cross-sectional areas of the trunk muscles in baseball batters were higher than those in untrained subjects who participated in our previous study. The ultrasonography-measured thicknesses at all 10 sites of the trunk muscles correlated highly with the magnetic resonance imaging-measured cross-sectional areas in baseball batters. [Conclusion] These results suggest that the thicknesses of the trunk muscles measured using ultrasonography can be used as a surrogate marker for the cross-sectional area measured using magnetic resonance imaging, in athletes who have larger trunk muscles than that of untrained subjects.

Applicability of ultrasonography for evaluating trunk muscle size: a pilot study

[Purpose] Ultrasonography (US) is widely applied to measure the muscle size in the limbs, as it has relatively high portability and is associated with low costs compared with large clinical devices such as magnetic resonance imaging (MRI). However, the applicability of US for evaluating trunk muscle size is poorly understood. This study aimed to examine whether US-measured muscle thickness (MT) in the trunk abdominal and back muscles correlated with MT and muscle cross-sectional area (MCSA) measured by MRI. [Subjects and Methods] Twenty-four healthy young males participated in this study. The MT and MCSA in the subjects were measured by US and MRI in a total of 10 sites, including the bilateral sides of the rectus abdominis (upper, central, and lower parts), abdominal wall, and multifidus lumborum. [Results] The interclass correlation coefficients of US-measured MT on the total 10 sites showed excellent values (n=12, 0.919 to 0.970). The US-measured MT significantly correlated with the MRI-measured MT (r=0.753 to 0.963) and MCSA (r=0.634 to 0.821). [Conclusion] US-measured MT could represent a surrogate for muscle size measured by MRI. The application of US for evaluating trunk muscle size may be a useful tool in the clinical setting.

Effects of stabilization training on trunk muscularity and physical performances in youth soccer players

The purpose of the present study was to examine the effects of stabilization training on trunk muscularity and physical performances in youth male soccer players aged 12-13 yrs (n = 28). The subjects allocated to training (TG, n = 16) performed a stabilization exercise program consisting of 5 exercises (elbow-toe, elbow-heel, side bridge, modified 1-legged squat, and bent-knee push-up) 4 times per week and a training program specific to soccer 6 times per week, whereas the others (control, n = 12) conducted the soccer training only for 6 months. Before and after the intervention, the cross-sectional areas (CSAs) of 5 muscles (rectus abdominus, oblique, psoas major, quadratus lumborum, and erector spinae) were determined using magnetic resonance imaging. Furthermore, peak torques during hip extension and flexion at 1.05 rad/second, heights of squat and countermovement jumps, and time taken to sprint 15 m were also measured. After 6 months, both groups significantly increased the CSAs of the 5 muscle groups (TG: 4.4-13.4%, control: 5.5-10.9%) and improved sprint time (TG: -1.4%, control: -1.6%), without significant effect of group, but only TG significantly increased the heights of squat (5.0%) and countermovement (6.8%) jumps. In addition, a greater increase in hip extension torque was found in TG (40.8%) than in control (17.4%). The current results indicate that, at least in early adolescent soccer players, adding stabilization exercise to soccer training cannot increase the trunk muscularity, but it will improve hip extensor strength and vertical jump performance.

Systematic review of core muscle activity during physical fitness exercises

A consensus has not been reached among strength and conditioning specialists regarding what physical fitness exercises are most effective to stimulate activity of the core muscles. Thus, the purpose of this article was to systematically review the literature on the electromyographic (EMG) activity of 3 core muscles (lumbar multifidus, transverse abdominis, quadratus lumborum) during physical fitness exercises in healthy adults. CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, PubMed, SPORTdiscus, and Web of Science databases were searched for relevant articles using a search strategy designed by the investigators. Seventeen studies enrolling 252 participants met the review's inclusion/exclusion criteria. Physical fitness exercises were partitioned into 5 major types: traditional core, core stability, ball/device, free weight, and noncore free weight. Strength of evidence was assessed and summarized for comparisons among exercise types. The major findings of this review with moderate levels of evidence indicate that lumbar multifidus EMG activity is greater during free weight exercises compared with ball/device exercises and is similar during core stability and ball/device exercises. Transverse abdominis EMG activity is similar during core stability and ball/device exercises. No studies were uncovered for quadratus lumborum EMG activity during physical fitness exercises. The available evidence suggests that strength and conditioning specialists should focus on implementing multijoint free weight exercises, rather than core-specific exercises, to adequately train the core muscles in their athletes and clients.

The hypertrophy of the lateral abdominal wall and quadratus lumborum is sport-specific: an MRI segmental study in professional tennis and soccer players

The aim was to determine the volume and degree of asymmetry of quadratus lumborum (QL), obliques, and transversus abdominis; the last two considered conjointly (OT), in tennis and soccer players. The volume of QL and OT was determined using magnetic resonance imaging in professional tennis and soccer players, and in non-active controls (n = 8, 14, and 6, respectively). In tennis players the hypertrophy of OT was limited to proximal segments (cephalic segments), while in soccer players it was similar along longitudinal axis. In tennis players the hypertrophy was asymmetric (18% greater volume in the non-dominant than in the dominant OT, p = 0.001), while in soccer players and controls both sides had similar volumes (p > 0.05). In controls, the non-dominant QL was 15% greater than that of the dominant (p = 0.049). Tennis and soccer players had similar volumes in both sides of QL. Tennis alters the dominant-to-non-dominant balance in the muscle volume of the lateral abdominal wall. In tennis the hypertrophy is limited to proximal segments and is greater in the non-dominant side. Soccer, however, is associated to a symmetric hypertrophy of the lateral abdominal wall. Tennis and soccer elicit an asymmetric hypertrophy of QL.

Soccer attenuates the asymmetry of rectus abdominis muscle observed in non-athletes

Purpose

To determine the volume and degree of asymmetry of the rectus abdominis muscle (RA) in professional soccer players.

Methods

The volume of the RA was determined using magnetic resonance imaging (MRI) in 15 professional male soccer players and 6 non-active male control subjects.

Results

Soccer players had 26% greater RA volume than controls (P<0.05), due to hypertrophy of both the dominant (28% greater volume, P<0.05) and non-dominant (25% greater volume, P<0.01) sides, after adjusting for age, length of the RA muscle and body mass index (BMI) as covariates. Total volume of the dominant side was similar to the contralateral in soccer players (P = 0.42) and in controls (P = 0.75) (Dominant/non-dominant = 0.99, in both groups). Segmental analysis showed a progressive increase in the degree of side-to-side asymmetry from the first lumbar disc to the pubic symphysis in soccer players (r = 0.80, P<0.05) and in controls (r = 0.75, P<0.05). The slope of the relationship was lower in soccer players, although this trend was not statistically significant (P = 0.14).

Conclusions

Professional soccer is associated with marked hypertrophy of the rectus abdominis muscle, which achieves a volume that is 26% greater than in non-active controls. Soccer induces the hypertrophy of the non-dominant side in proximal regions and the dominant side in regions closer to pubic symphysis, which attenuates the pattern of asymmetry of rectus abdominis observed in non-active population. It remains to be determined whether the hypertrophy of rectus abdominis in soccer players modifies the risk of injury.