Asymmetry of Musculature and Hand Grip Strength in Bodybuilders and Martial Artists

The Association Between Grip Strength, Upper Body Power, and Limb Dominance in a Military Population

INTRODUCTION

Military service members rely on upper body strength and power to accomplish tasks such as carrying heavy weapons and gear, rappelling, combat grappling, and marksmanship. Early identification of the factors that lead to reduced upper body strength and power would enable leadership to predict and mitigate aspects that decrease military operational readiness and increase injury risk. The purpose of this study was to investigate the relationship between grip strength and upper body power in U.S. Infantry Marines. We hypothesized that dominant arm grip strength would show a strong positive correlation with upper body power and that the dominant arm would be more powerful than the non-dominant arm.

MATERIALS AND METHODS

A total of 120 U.S. Marines completed 3 maximum effort isometric grip strength trials with their dominant hand and 3 maximum effort ballistic pushups on a ForceDecks force plate system. Force plate data were used to estimate pushup height and peak power. Maximum grip strength, pushup height, and peak power across the 3 trials were used for analysis. Pearson's correlation was used to test for associations between peak power, pushup height, and grip strength. Paired t-tests were used to test for differences in peak power between the dominant and non-dominant arms.

RESULTS

A very weak correlation was found between grip strength and upper body power, but there was no relationship between grip strength and pushup height. Additionally, there were no significant differences in upper body power between the dominant and non-dominant arms.

CONCLUSIONS

The results of this study suggest that grip strength is not predictive of upper body power and cannot be used as a stand-alone measure of physical readiness in a military unit. These findings do not, however, degrade the potential of both measures to predict and inform health status and physical readiness. Future prospective research should be conducted to determine if either of these measures can be used as indicators of performance and/or injury susceptibility and if limb dominance plays a role in injury incidence within the upper extremity.

The Influence of the Dominant Leg in Body Asymmetries in Children and Adolescent Male Soccer Players

The current study aimed to examine (a) whether the dominant leg (DL) was associated with the contralateral side of functional scoliosis and (b) if any of the postural asymmetries' evaluation variables may be a reliable predictor of the functional scoliosis development in young male soccer players. Six hundred-nine (n = 609) male soccer players (age: 10.8 ± 2.7 years; height: 147 ± 17 cm; weight: 43.4 ± 14.6 kg; DL: Right 81.6%, Left 14%, Both 4.4%) participated in this study. The spinal asymmetries evaluation included thoracic kyphosis, lumbar lordosis, truncal rotation, shoulders alignment from posterior view, anterior and posterior pelvic tilt, anterior superior iliac spine (ASIS), hamstring tightness, and lower extremities discrepancy. A significant association was observed between the DL and the truncal rotation side: χ2(4) = 30.84, p = 0.001, V = 0.16. Participants with longer left legs were likelier to present a spinal asymmetry (OR = 1.18). The participants with higher left shoulders were 2.13 times more likely to have spinal asymmetry than the participants with normal shoulders level. Participants with left ASIS higher were 3.08 times more likely to present asymmetry than those with normally aligned ASIS levels. There was also a significant association between the DL and the side of truncal rotation: χ2(2) = 13.30, p = 0.001, V = 0.449. Logistic regression analysis for the functional scoliotic group and truncal rotation side demonstrated that the taller participants and participants with shorter right legs were more likely to have asymmetry on the left side (OR = 1.29, OR = 0.32). Participants with greater right hamstring stiffness were likelier to have a truncal rotation on the right side (OR = 0.93). Participants with higher left shoulders were 0.20 times less likely to have a truncal rotation on the left side than the participants with normal shoulders level. In conclusion, leg dominance in children and in youth soccer players may be a factor causing truncal rotation on the contralateral side. Additional causes, such as leg length discrepancy and pelvic tilt, may progressively lead to functional scoliosis.

Multimodal sensorimotor assessment of hand and forearm asymmetries: a reliability and correlational study

Background

Effective rehabilitation of upper limb musculoskeletal disorders requires multimodal assessment to guide clinicians' decision-making. Furthermore, a comprehensive assessment must include reliable tests. Nevertheless, the interrelationship among various upper limb tests remains unclear. This study aimed to evaluate the reliability of easily applicable upper extremity assessments, including absolute values and asymmetries of muscle mechanical properties, pressure pain threshold, active range of motion, maximal isometric strength, and manual dexterity. A secondary aim was to explore correlations between different assessment procedures to determine their interrelationship.

Methods

Thirty healthy subjects participated in two experimental sessions with 1 week between sessions. Measurements involved using a digital myotonometer, algometer, inclinometer, dynamometer, and the Nine-Hole Peg test. Intraclass correlation coefficients, standard error of the mean, and minimum detectable change were calculated as reliability indicators. Pearson's correlation was used to assess the interrelationship between tests.

Results

For the absolute values of the dominant and nondominant sides, reliability was 'good' to 'excellent' for muscle mechanical properties, pressure pain thresholds, active range of motion, maximal isometric strength, and manual dexterity. Similarly, the reliability for asymmetries ranged from 'moderate' to 'excellent' across the same parameters. Faster performance in the second session was consistently found for the Nine-Hole Peg test. No systematic inter-session errors were identified for the values of the asymmetries. No significant correlations were found between tests, indicating test independence.

Conclusion

These findings indicate that the sensorimotor battery of tests is reliable, while monitoring asymmetry changes may offer a more conservative approach to effectively tracking recovery of upper extremity injuries.

An Indian classical dance form, Kathak in maintaining handgrip strength symmetry and reducing the risk of hypertension

BACKGROUND

The present paper aimed to study handgrip strength (HGS) asymmetry and its association with hypertension in a sample of Kathak dancers and non-dancers of North India.

METHODS

Data on HGS and blood pressure were collected from 206 Kathak dancers and 235 age-matched controls, using standardized protocols. Pearson correlation coefficients assessed the association between HGS and hypertension, and binary logistic regression identified the risk of developing hypertension.

RESULTS

HGS asymmetry was higher among non-dancers. In Kathak dancers, systolic blood pressure (SBP) was positively correlated with HGS and negatively correlated with HGS asymmetry whereas diastolic blood pressure (DBP) was negatively correlated with both HGS and HGS asymmetry. Dancers with high HGS, have significantly reduced risk of developing hypertension. Non-dancers with HGS asymmetry were 1.8 times more likely to report hypertension, relative to dancers.

CONCLUSION

Kathak may be used as an alternative method for maintaining HGS symmetry and reducing the risk of developing hypertension.

The Impact of Physical Activity on Adolescent Idiopathic Scoliosis

The prevalence of adolescent idiopathic scoliosis (AIS) is increasing, partly due to a lack of physical activity. In a cross-sectional study with 18,216 pupils (5th, 6th, and 8th grades) from four Croatian counties using the forward bend test (FBT; presumed AIS), the prevalence of AIS and its correlation with physical activity were evaluated. Pupils with presumed AIS were less physically active than their peers without scoliosis (p < 0.001). Abnormal FBT was more prevalent among girls than boys (8.3% vs. 3.2%). Boys were more physically active than girls (p < 0.001). Pupils with presumed AIS were less physically active than their peers without scoliosis (p < 0.001). A higher prevalence of presumed AIS was found among inactive or just recreationally active schoolchildren than among those engaged in organized sports (p = 0.001), girls especially. Pupils with presumed AIS were less active and had fewer weekly sports sessions than their peers without scoliosis (p < 0.001). Notably low prevalence of AIS was detected among pupils engaged in soccer (2.8%, p < 0.001), handball (3.4%, p = 0.002), and martial arts (3.9%, p = 0.006), while it was higher than expected in swimming (8.6%, p = 0.012), dancing (7.7%, p = 0.024), and volleyball (8.2%, p = 0.001) participants. No difference was detected for other sports. A positive correlation was found between time spent using handheld electronic devices and the prevalence of scoliosis (r_s = 0.06, p < 0.01). This study confirms the increasing prevalence of AIS, particularly among less athletic girls. Further, prospective studies in this field are required to explain whether the higher prevalence of AIS in these sports is due to referral or other aspects.

More than just a side effect: Dynamic knee valgus and deadbug bridging performance in youth soccer players and alpine skiers have similar absolute values and asymmetry magnitudes but differ in terms of the direction of laterality

From a preventative perspective, leg axis and core stabilization capacities are important for soccer players and alpine skiers; however, due to different sport-specific demands, the role of laterality clearly differs and may result in functional long-term adaptations. The aims of this study are 1) to determine whether there are differences in leg axis and core stability between youth soccer players and alpine skiers and 2) between dominant and non-dominant sides, and 3) to explore the outcomes of applying common sport-specific asymmetry thresholds to these two distinct cohorts. Twenty-one highly trained/national-level soccer players (16.1 years, 95% CI: 15.6, 16.5) and 61 alpine skiers (15.7 years, 95% CI: 15.6, 15.8) participated in this study. Using a marker-based 3D motion capture system, dynamic knee valgus was quantified as the medial knee displacement (MKD) during drop jump landings, and core stability was quantified as the vertical displacement during deadbug bridging exercise (DBBdisplacement). For the analysis of sports and side differences, a repeated-measures multivariate analysis of variance was used. For the interpretation of laterality, coefficients of variation (CV) and common asymmetry thresholds were applied. There were no differences in MKD or DBBdisplacement between soccer players and skiers or between the dominant and non-dominant sides, but there was an interaction effect side*sports for both variables (MKD: p = 0.040, η2p = 0.052; DBBdisplacement: p = 0.025, η2p = 0.061). On average, MKD was larger on the non-dominant side and DBBdisplacement laterality on the dominant side in soccer players, whereas this pattern was reversed in alpine skiers. Despite similar absolute values and asymmetry magnitudes of dynamic knee valgus and deadbug bridging performance in youth soccer players and alpine skiers, the effect on the direction of laterality was opposite even though much less pronounced. This may imply that sport-specific demands and potential laterality advantages should be considered when dealing with asymmetries in athletes.

Grip Strength and Sports Performance in Competitive Master Weightlifters

Grip strength (GS) is correlated with major muscle group strength; weakness and asymmetry in older adults are predictive of future disease and functional limitation risk. GS at different ages and hand symmetry for Olympic-style weightlifters and their association with performance have not been established. GS was measured in 164 athletes participating in the 2022 World Master Weightlifting Championships. The objectives wereto study the magnitude of the age-associated decline in GS in weightlifters and the association of GS with weightlifting performance. Hand symmetry was considered as a potential factor in successful lifts. Ages ranged from 35 to 90 (mean 53 years). Participants reported weekly training averages of 8.3 h of weightlifting and 4.1 additional hours of physical activities. The age-associated decline in GS was less steep than the decline in weightlifting performance. GS was lower in weightlifters compared to athletes in other sports that require grasping or force application (t = -2.53, p=0.053 for females; t = -2.62, p= 0.029 for males). The rate of decline was similar across different populations (weightlifters, other athletes, community-dwelling adults). Height and age were associated with GS, but performance level and training hours were not. GS was associated with snatch performance (t = 3.56, p < 0.001) but not with clean and jerk (t = 0.48, p = 0.633).

Seven-month wintertime supplementation of 1200 IU vitamin D has no effect on hand grip strength in young, physically active males: A randomized, controlled study

Background

Study Design

Methods

Results

Conclusion

Analysis of the Contact Area for Three Types of Upper Limb Strikes

Performance in strike combat sports is mostly evaluated through the values of the net force, acceleration, or speed to improve efficient training procedures and/or to assess the injury. There are limited data on the upper limb striking area, which can be a useful variable for contact pressure assessment. Therefore, the aim of this study was to determine the contact area of the upper limb in three different strike technique positions. A total of 38 men and 38 women (n = 76, 27.3 ± 8.5 years of age, 73.9 ± 13.8 kg of body weight, 173.3 ± 8.4 cm of body height) performed a static simulation of punch with a fist, palm strike, and elbow strike, where three segments of the right upper limb were scanned. The analysis of 684 images showed a correlation (r = 0.634) between weight and punch technique position in men and significant differences in elbow strike (p < 0.001) and palm strike (p < 0.0001) between women and men. In both groups, the palm demonstrated the largest area and the elbow the smallest one. These data may be used to evaluate strike contact pressure in future studies in forensic biomechanics and assessment of injury in combat sports and self-defense.

Analysis of the fight-ending chokes in the history of the Ultimate Fighting Championship™ mixed martial arts promotion

OBJECTIVE

Knowledge of sportive chokes is vital to the practice of Sports Medicine when providing care at mixed martial arts and submission grappling events. This is a descriptive analysis of fight-ending chokes to help provide data on the topic not previously presented.

METHODS

An analysis was done on every fight-ending choke in the history of the UFC™ mixed martial arts promotion. Investigators focused on the frequency of chokes, types of chokes, handedness of the chokes, and whether chokes resulted in loss of consciousness. This analysis was done using existing fight outcome reports and video analysis of every choke that ended a fight in UFC™ history.

RESULTS

During the study period there were 904 such chokes, comprising 15.5% of fight outcomes and 76.2% of grappling submissions. The makeup of right (50.1%) and left (49.9%) handedness of the chokes has been essentially identical (χ2 [1] = 0.0011, p =.947, phi =.00). Most of the fight-ending chokes culminated in voluntary submission; however, 11% resulted in loss of consciousness. The rear naked choke (RNC) was significantly more frequent than other chokes, comprising 49.1% of the total choke finishes; 19 other choke types accounted for the remaining 50.9%.

CONCLUSION

Fight-ending chokes have been common in MMA. Many types of chokes have successfully ended UFC™ fights, with the RNC accounting for almost half of fight-ending chokes. Loss of consciousness occurred in 11% of fight-ending chokes. Right and left handed chokes were utilized equally.

Body Composition and Bioelectrical-Impedance-Analysis-Derived Raw Variables in Pole Dancers

Few data are available on the body composition of pole dancers. Bioelectrical impedance analysis (BIA) is a method that is used to estimate fat-free mass (FFM) and fat mass (FM), while raw BIA variables, such as the impedance ratio (IR) and phase angle (PhA), are markers of body cell mass and the ratio between extracellular and total body water. The aim of this study was to evaluate the body composition of pole dancers compared to controls, in particular, those raw BIA variables that are considered as markers of muscle composition. Forty female pole dancers and 59 controls participated in the study. BIA was performed on the whole body and upper and lower limbs, separately, at 5, 50, 100 and 250 kHz. The FFM, FFM index, FM and body fat percentage (BF%) were predicted. The bioelectrical impedance indexes IR and PhA were also considered. Pole dancers exhibited higher FFMI and BI indexes and lower BF%. PhA was greater and IRs were smaller in pole dancers than in controls for the whole body and upper limbs. Considering the training level, FFM, whole-body IR and PhA were higher in the professionals than non-professionals. Raw BIA variables significantly differed between the pole dancers and controls, suggesting a higher BCM; furthermore, practicing pole dancing was associated with a greater FFM and lower FM.

Get a Grip: Variation in Human Hand Grip Strength and Implications for Human Evolution

Although hand grip strength is critical to the daily lives of humans and our arboreal great ape relatives, the human hand has changed in form and function throughout our evolution due to terrestrial bipedalism, tool use, and directional asymmetry (DA) such as handedness. Here we investigate how hand form and function interact in modern humans to gain an insight into our evolutionary past. We measured grip strength in a heterogeneous, cross-sectional sample of human participants (n = 662, 17 to 83 years old) to test the potential effects of age, sex, asymmetry (hand dominance and handedness), hand shape, occupation, and practice of sports and musical instruments that involve the hand(s). We found a significant effect of sex and hand dominance on grip strength, but not of handedness, while hand shape and age had a greater influence on female grip strength. Females were significantly weaker with age, but grip strength in females with large hands was less affected than those with long hands. Frequent engagement in hand sports significantly increased grip strength in the non-dominant hand in both sexes, while only males showed a significant effect of occupation, indicating different patterns of hand dominance asymmetries and hand function. These results improve our understanding of the link between form and function in both hands and offer an insight into the evolution of human laterality and dexterity.

Long-term effects of asymmetrical posture in boxing assessed by baropodometry

BACKGROUND

Asymmetrical posture maintained over long training periods may affect phenotypic plasticity, resulting functional to sporting goal but negative to the locomotor system. Aim of this study was to quantitatively evaluate these long-term effects in competitive boxers.

METHODS

Baropodometric analysis was used to assess 20 competitive boxers and 20 non-sportsmen in upright bipedal posture for 5 s and for 51.2 s with open (OE) and closed (CE) eyes.

RESULTS

The boxers' group (BOX) showed a larger total foot load (TFL) (p=0.022) on the right foot and a larger rearfoot load (RfL) (p=0.011) on the left foot compared to non-sport controls (CTR). Moreover, a larger forefoot load (FfL) (p=0.001) on the right foot respect to left one was found in the BOX group, with the inversion of the RfL to FfL ratio (p=0.001) between two feet, while no significant differences were found in the CTR group. These findings, associated to a significantly larger center of foot angle (COF) in the BOX group, may indicate an anticlockwise rotation of the anatomical structures above the ankle joint of the right hemisoma respect to the left one, that appears to be consistent with the orthodox stance. Eventually, the BOX group showed a larger centre-of-pressure sway area (COPsa) in the OE condition than what measured in the CE and a significant difference in Romberg Index (BOX< CTR).

CONCLUSIONS

The results of this study seem to confirm the theory of neuromuscular plasticity imprinted by the repetitive movements and long-lasting postures. Moreover, competitive boxers show an increase of proprioceptive function and a decrease of visual dependence on the postural control.

Gender Differences in Neuromuscular, Haematological and Urinary Responses during Padel Matches

Research on the acute physiological response to a padel match is limited. The present study aimed to: (a) evaluate neuromuscular, urinary, and hematological responses after simulated padel competition (SC) and (b) analyze possible gender differences. In this study, 28 high-level padel players participated (men = 13, age = 26.83 ± 6.57 years; women = 15, age = 30.07 ± 4.36 years). The following parameters were analyzed before and after SC: neuromuscular (hand grip strength, squat jump (SJ), countermovement jump (CMJ), and Abalakov jump (ABK)), hematological (red blood cells, hemoglobin, and hematocrit), and urinary (pH, specific gravity, microalbuminuria, and red blood cells). Significant gender differences were found in neuromuscular and hematological responses, with men obtaining higher values (p < 0.05). For the SC influence, changes were noted in ABK and microalbuminuria (p < 0.05). The percentages of change in hand grip strength, SJ (height and watts), CMJ (height), and ABK (height) were higher for men than women (p < 0.05). SC negatively influenced the neuromuscular parameters to a greater extent in women. Our results could be related to gender differences in game actions, the temporal structure, and anthropometric and physiological characteristics. Game dynamics and a different organic response between male and female padel playing were confirmed.

Strength Asymmetries in Young Elite Sailors: Windsurfing, Optimist, Laser and 420 Classes

Strength asymmetries in the upper and lower limbs may affect the body movements of the joints or limbs. Although asymmetries in the upper limbs have been studied in sailors, those in lower limbs have not been evaluated in this sport population. The aims of this study were: (i) to analyze lower limb asymmetries in young elite sailors in order to quantify the magnitude of asymmetry between limbs for variables that were established as reliable in a healthy population, and (ii) to evaluate the presence of differences between classes and sexes in inter-limb asymmetries in elite youth sailors. Sixty-eight young Spanish elite sailors (9–19 years of age) participated voluntarily in our study. Single-leg vertical countermovement jump (VCJ), single-leg horizontal countermovement jump and hand dynamometry tests were used to evaluate the strength of the upper and lower limbs. More than 50% of the sailors presented asymmetries in the lower limbs. The boys’ group and Optimist class presented a greater percentage of strength asymmetry.

Bilateral asymmetry in arm anthropometric measurements according to laterality and nutritional status in children and adolescents from 6 to 12 years old

OBJECTIVE

To compare and correlate anthropometric measurements of the left arm versus the right arm and to establish their relation to laterality, sex, and nutritional status in children and adolescents from 6 to 12 years of age.

METHODS

A cross-sectional study included 605 children and adolescents (285 males; 320 females), with a middle socioeconomic status, that attended an urban elementary school. Anthropometric measurements were taken in both arms, along with height and weight, to assess nutritional status. Self-reported hand preference was recorded.

RESULTS

A total of 49.3% were females and 93% of the subjects were right-handed (n = 563). The mean comparison of right arm and left arm measurements and areas, according to laterality, showed differences in arm fat measurements, with higher values in the right arm. However, the mean difference in triceps skinfold and upper arm measurements between the right arm and left arm was smaller than the technical error of measurement. Significant differences were observed between arm measurements and areas. Upper arm and total upper arm areas of both arms had the highest regression coefficients, with an adjusted R² of .98, whereas the arm fat index had the lowest (adjusted R² of .88). Adjusting the previous differences between the right arm and left arm by age, sex, BMI, and laterality produced similar results.

CONCLUSIONS

Statistical but not clinically significant differences were found between some measurements and areas of both arms, discretely modified in models adjusted for age and BMI, so the measurements can be made on either arm.

Asymmetry of Muscle Mass Distribution and Grip Strength in Professional Handball Players

Handball is among the disciplines that impose a significant degree of asymmetry on the body movement. The aim of the study is to assess the influence of physical effort on the occurrence of asymmetry in body musculature and in isometric strength of handball players. The study examined 36 professional handball players. Players' height and body mass were measured as to calculate their body mass indexes (BMIs). Segmental bioelectrical impedance analysis (SBIA) was used to assess: the percentage of fat mass, total muscle mass (MM), musculature of the right and left side of the body, and body segments (trunk, upper and lower limbs). Moreover, grip strength was also measured. The assessment confirmed the existence of discrepancies in the right and left sides of players' bodies for the majority of the parameters. Cross-asymmetry and significant bilateral discrepancies in trunk musculature were also observed. Morphological asymmetry may impact performance in sports since it can cause unfavorable functional changes, which in turn increase the risk of injury and conditions caused by overexertion. Therefore, we believe it is important to emphasize the importance of individualized symmetrization during sports practice and consistent monitoring of the asymmetries occurring in different body parts; this should both improve one's sports results and minimize the risk of injury.