Absolute Peak Torque Research Articles

Plyometric training with additional load improves jumping performance and isokinetic strength parameters of knee extensors and flexors in young male soccer players

ABSTRACT This study investigated the effect of plyometric training with and without additional load on young male soccer players’ jumping ability and isokinetic strength. Methods: In this randomized controlled trial, 39 U-17 male trained soccer players were randomly divided into plyometric training with additional load (PT+AL), plyometric training with just bodyweight (PTBW) and control (CON) groups. PT+AL and PTBW were performed for six weeks (2 days/week). Absolute peak torque (APT), relative peak torque (RPT), average peak torque (AvPT), time-to-peak torque (TPT), average rate of force development (AvRFD), vertical jump height (VJH), standing long jump (SLJ) and 15-second repeated jump tests (RJ15s) were assessed before and after the interventions. The findings showed that the performance of knee extensors in TPT-60°/s and AvRFD-60°/s, and knee flexors in APT-60°/s, RPT-60°/s, AvPT-60°/s, AvPT-120°/s, AvRFD-60°/s and AvRFD-120°/s significantly increased after PT+AL, compared to the CON (p < 0.05). Also, a significant improvement in jumping ability was observed in PT+AL compared to CON (p < 0.05). Additionally, PTBW also improved the performance of knee flexors in TPT-120°/s and AvRFD-120°/s, as well as RJ15s performance compared to the CON (p < 0.05). Furthermore, knee flexors AvRFD-60°/s increased significantly after PT+AL, compared to PTBW (p < 0.05). SO, plyometric training, with or without additional load, improved young male soccer players’ strength and jumping ability. However, strength parameters – especially the rate of force development – showed a greater increase following PT + AL compared to PTBW.

Running Plus Strength Training Positively Affects Muscle Strength and Quality in Both Younger (Below 50 Years Old) and Older (Above 50 Years Old) Women.

Sarcopenia is a muscular disease characterized by loss of muscular strength and function, affecting mainly women, and associated with increased mortality risk. The aim of this study was to compare active women with inactive women of different age groups regarding muscle mass, strength, and muscle quality. This study included 147 women (85 runners and 62 inactive), divided into <50 and ≥50 years old. Participants were evaluated for knee flexor and extensor peak torque (PT), body composition, and training habits. For knee extensor muscles, there was an age group effect (F(2.146) = 40.5; p < 0.001) on absolute PT (Nm); an age group effect (F(2.146) = 44.1; p < 0.001) and a physical activity group effect (F(2.146) = 113.0; p < 0.001) on PT adjusted by body mass (Nm/kg); and an age group effect (F(2.146) = 36.9; p < 0.001) and a physical activity group effect (F(2.146) = 6.1; p = 0.014) on PT adjusted by lean mass (Nm/kgLM). There was no interaction effect. In both age groups, active women had greater strength and higher muscle quality than inactive women, but the difference in strength, muscle mass, and muscle quality between younger and older women were the same among runners and inactive women.

Age-related effects on absolute and relative isokinetic knee extensor strength in community-dwelling older men and women at a French geriatric day hospital.

Isokinetic knee extensor strength is poorly evaluated in geriatric day hospitals (GDHs), despite its potential functional significance compared to grip strength. This study aimed to investigate age-related effects on absolute and relative isokinetic knee extensor peak torque (KEPT) data in community-dwelling older GDH patients. A total of 472 French GDH patients (179 men and 293 women, aged 75-94 years) participated in this study. Absolute and relative KEPT were measured at six distinct angular velocities between 0.52 and 3.14 rad/s. In addition, comfortable gait speed and grip strength were assessed. Participants were stratified by sex and age using 5-year intervals. One-way ANOVAs were used to examine age-related effects on KEPT values. Multiple linear regression models were employed to investigate the associations between gait speed and both mean KEPT values and grip strength, with separate models conducted on absolute and relative values. The recruited GDH patients presented lower absolute and relative KEPT values in comparison with established reference values for healthy community-dwelling older individuals, with men being consistently stronger than women. Notably, there was a significant decline in both absolute and relative KEPT values beyond the age of 85 for both sexes. Importantly, the multiple linear regression analyses conducted revealed a significant positive relationship between gait speed and mean KEPT values, surpassing the association with grip strength. These findings underscore the clinical importance of assessing isokinetic knee extensor strength in community-dwelling older GDH patients, particularly for tailoring personalized physical activity interventions.

Strength and Functional Outcomes Following Achilles Tendon Reconstruction With Hamstring Tendon Autograft Augmentation.

The proposed advantages of hamstring autograft reconstruction when compared to alternative procedures, such as flexor hallucis longus (FHL) transfer, V-Y lengthening, and allograft reconstruction, are improved healing and reproduction of normal tendon biomechanics and reduced morbidity within the foot and ankle. In this study, we examined the effect of Achilles tendon reconstruction using hamstring autografts on strength and functional outcomes. Patients who underwent Achilles repair with a hamstring autograft for insertional or midsubstance tendinopathy, delayed diagnosis of rupture, or infection after primary repair were evaluated for inclusion. Forty-six patients were identified; 12 further augmented with an FHL transfer are included in the analysis. Isokinetic testing was completed with a Biodex dynamometer under supervision of a physical therapist masked to surgical side. Pre- and postoperative Foot and Ankle Outcome Scores (FAOS, before March 2016) or Patient-Reported Outcomes Measurement Information System (PROMIS, after March 2016) surveys were collected. For knee flexion, peak torque was not significantly different when comparing operative and nonoperative sides at 180 degrees/second (45.38 Nm vs 45.96 Nm; P = .69) nor at 300 degrees/second (44.2 Nm vs 47.02 Nm; P = .069). Knee extension absolute peak torque was only found to be significantly weaker on the operative side at the faster testing (75.5 Nm vs 79.56 Nm; P < .05). Peak ankle plantarflexion torque was significantly weaker on the operative side at both the slower speed (60 degrees/second: 39.9 Nm vs 48.76 Nm; P < .005) and the faster speed (120 degrees/second: 31.3 Nm vs 40.7 Nm; P < .001). Average power for ankle plantarflexion did not differ significantly from the operative side to the nonoperative side in the slower test (26.46 W vs 27.48 W; P = .60) but did significantly differ on the faster test (32.13 W vs 37.63 W; P = .041). At an average of 19.9 months postoperation, all physical function and pain-related patient-reported outcome scores showed clinically and statistically significant improvement. Achilles reconstruction with a hamstring autograft ± FHL transfer allowed patients with severe Achilles pathology to return to good subjective function, with modest deficits in calf strength compared with the uninjured side. Overall knee flexion strength did not appear impaired. These results suggest that hamstring autograft reconstruction is a viable method to treat these complex cases involving a lack of healthy tissue, allowing patients to return to symptom-free physical function and athletic activity. Level IV, case series.

Higher Eccentric Hamstring Muscle Fatigue After Participation in a Soccer Match in Young Female Athletes.

Hamstring (HS) strength deficits and imbalances have been identified as risk factors for sustaining anterior cruciate ligament (ACL) injuries and muscular strains, with HS injuries being the most prevalent muscle injuries in soccer athletes. The aim of this study was to investigate HS eccentric strength before and after a soccer match in both male and female soccer athletes. Soccer athletes have changes in eccentric HS strength after a soccer game. Cohort observational study. Level 3. HS eccentric strength (mean and absolute peak torque and total work) was measured in 64 healthy male and female competitive football athletes (14-25 years) with an automatic device during the execution of the Nordic hamstring exercise (NHE) test before and after a 90-minute soccer match. The anterior-knee laxity (AKL) was quantified with an arthrometer. Mean and absolute eccentric HS peak torque decreased by 24.5 N.m (-12.34%; P < 0.01) and 21.9 N.m (-10.08%; P < 0.01) in female athletes, whereas their male peers improved by 19.9 N.m (+9.01%; P = 0.01) and by 20.9 N.m (+8.51%; P = 0.02), respectively. HS total work in female athletes decreased by 831.1 J (P < 0.01) compared with the male athlete reduction of 235.3 J. Both the pre- versus postmatch intersex mean and absolute eccentric HS peak torque changes were significant (P < 0.01), as were the changes in HS total work (P < 0.01). The pre- versus postmatch AKL difference and the dominant versus nondominant limb comparison of the strength parameters were not significantly different. Younger female athletes (14-19 years old) presented a greater decrease in mean and absolute peak HS eccentric strength compared with those in older female athletes and men. HS eccentric strength and work differ based on athlete sex, as measured by the NHE test. Mean peak, absolute peak, and total work showed greater reductions in female athletes than those in their male peers. The subgroup of 14- to 19-year-old female athletes experienced the highest reduction in strength parameters.

Isokinetic profiles of hamstring and quadriceps muscles in the police special force operators

Knee injuries are of concern to police. The aims of this study were to determine initial reference values for isokinetic knee extension and flexion in police special force operators to explore the conventional hamstring contraction (Hcon) quadriceps contraction (Qcon) ratio, and to determine the limb symmetry index of the quadriceps and hamstring muscles. Absolute and relative isokinetic torque of quadriceps and hamstrings were assessed in 10 police special force operators using an isokinetic dynamometer Con-Trex. Subjects performed maximal knee extension and flexion at a contraction velocity of 60°/s at 90° of knee flexion. Means, standard deviations, 95% confidence interval values, and effect sizes were calculated. A paired samples t-test was used to test the between-leg differences in absolute and relative torques of quadriceps and hamstring muscles and to test the between-leg difference in Hcon/Qcon ratios as well as strength asymmetries of quadriceps and hamstrings. Descriptive statistics revealed torque values similar to athletes, and paired sample t-tests showed no significant between-leg differences in torque values at a group level. Small effect sizes were observed between legs in both the absolute and relative peak torque of the hamstring muscles. While, on a group level, no Hcon/Qcon ratio disparity between legs or asymmetries were observed, individual results indicated a trend towards greater dispersion for the dominant leg and some individual results indicated an increased asymmetry in isometric strength of hamstrings. The study provides normative data for this unique police population and highlights the need for relative strength work in this population.

Examining the Link between Isokinetic Strength Metrics and Ball Speed in Women’s Soccer

The shot performance of female soccer players is one of the most critical factors in winning a soccer match. It is essential to thoroughly clarify the kinetic factors that can improve shot performance. This study explores the connections between ball velocity post-shooting and isokinetic knee extension (EXT) and flexion (FLX) strength performances among female soccer players. Thirteen voluntary players from professional leagues took part in the research study. The study analyzed the average and peak concentric (Con) and eccentric (Ecc) torques, isometric (Iso) strength performances at angular velocities of 60°/s, 180°/s and 300°/s, the time required to reach peak torque, and ball velocities during shooting. The relationships among these variables were investigated separately for the dominant (D) and non-dominant (ND) legs. The analysis unveiled significant correlations between ball velocities and D-EXT (Absolute) peak torque at an angular velocity of 60°/s (r = 0.597; p &lt; 0.05), D-%IPS (r = −0.580; p &lt; 0.05), and ND-FLX (Absolute) average torque (r = 0.559; p &lt; 0.05). Moreover, notable associations were observed between ball velocities and ND-EXT (Absolute) (r = 0.581; p &lt; 0.05), as well as ND-FLX (Absolute) (r = 0.602; p &lt; 0.05) average torques at an angular velocity of 180°/s. Additionally, significant relationships were found between ball velocities and peak (r = 0.664; p = 0.013) and average (r = 0.660; p = 0.014) torques generated during ND-EXT (Absolute) at an angular velocity of 300°/s. However, the connections between the time to reach peak torque, eccentric and isometric forces, and ball velocities were not statistically significant (p &gt; 0.05). The results of the study indicate that enhancing concentric isokinetic strength development at 60°/s, 180°/s, and 300°/s angular velocities, along with balanced strengthening of the ND extremity, holds paramount importance in elevating shot performance among female soccer players, particularly in the context of rapid shot strategies.

Sport-Related Effect on Knee Strength Profile during Puberty: Basketball vs. Soccer.

The present study examined and compared the isokinetic peak torque and the reciprocal ratios of the knee joint between young basketball and soccer players. An amount of 100 soccer and 100 basketball players took part in this study and were separated into five equal groups (n = 20), according to their chronological age (12, 13, 14, 15, and 16 years old). The absolute concentric (CON) and eccentric (ECC) peak torque of the knee flexor and extensor muscles (at 60°/s, 180°/s) were assessed using a Cybex Norm dynamometer, and the relative peak torque (per unit of body mass), as well as the conventional (CON/CON; ECC/ECC) and functional (CON/ECC; ECC/CON) ratios, were calculated. Data analysis indicated that the basketball players had higher absolute peak torque values than the soccer players throughout their developmental ages (p < 0.05). When the isokinetic peak torque values were normalized relative to body mass, no differences were observed between basketball and soccer players in any age group (p > 0.05). Additionally, no differences were observed in conventional and functional ratios between soccer and basketball players (p > 0.05). In conclusion, it appears that, during developmental ages (12-16 years old), the isokinetic strength profile (independent of body mass affecting absolute values) of knee extensor and flexor muscles develops similarly in basketball and soccer players.

Mode-specific Differences In Exercise-induced Fatigability And The Bilateral Deficit During Isokinetic Leg Extensions In Women.

Exercise-induced fatigability (EF) is defined as a fatigue-induced decline in force production and has been reported to exhibit mode-specific differences where unilateral (UL) tasks exhibit greater EF than bilateral (BL) tasks. While women have been reported to display a greater resistance to fatigue than men, few studies have examined whether women exhibit mode-specific differences in EF. Furthermore, few studies have examined the influence of EF on the bilateral deficit (BD). PURPOSE The purpose of the present study was to examine the patterns of responses for normalized isokinetic peak torque and the BD during fatiguing, maximal, isokinetic UL and BL leg extensions in women. METHODS Ten women (Mean ± SD; age = 20.9 ± 2.08 years; height = 170.4 ± 6.5 cm; body mass = 63.0 ± 7.1 kg) performed 50 UL and BL maximal, concentric, isokinetic leg extensions at 180°·s-1 on three separate visits. Each visit was characterized by a fatiguing task of 50 repetitions with either the dominant limb (DL), non-dominant limb (NL), or both limbs (BL) in random order. Isokinetic peak torque values were averaged across 5 consecutive repetitions and normalized to the value at repetition 5 for the respective fatiguing task. A bilateral deficit index (BDI) was quantified as: BDI = [100 × BL/ (NL + DL)] - 100 with the absolute isokinetic peak torque values throughout the 50 repetitions. The mean differences for the normalized isokinetic peak torque values were examined with a 3 (Condition [BL, DL, NL]) × 10 (Repetition [5-50]) repeated measures (RM) ANOVA. The mean changes across repetitions for the BDI were examined with a 1 × 10 (Repetition [5-50]) RM ANOVA. RESULTS The 3 × 10 RM ANOVA demonstrated a significant (p < 0.01, η2p = 0.21) interaction with post-hoc analyses indicating an earlier decline in normalized peak torque for the DL (repetition 30) and NL (repetition 25) conditions than the BL (repetition 50) condition. The 1 × 10 RM ANOVA demonstrated no significant mean changes for the BDI (p = 0.05, η2p = 0.29). CONCLUSION These results indicated that the women exhibited a greater EF during UL compared to BL fatiguing, maximal, isokinetic leg extensions. While all participants exhibited a BD, there were no significant changes in the BD across the fatiguing task. Future studies are warranted to compare the mechanisms of task-specific EF between women and men.

The influence of growth and development on shoulder rotators strength in young male and female elite tennis players.

Tennis practice requires a lot of technical, physical and mental qualities that have to be trained from the youngest age. The important number of hours spent on the court can lead, medium-to-long term to strength or flexibility adaptations, even in the youngest players. The current study aimed to explore the developmental consequences of repetitively playing tennis on shoulder range of motion and shoulder rotators' strength in elite male and female tennis players. Eigthy four painfree elite tennis players were assessed during preseason between 2009 and 2019. Clinical assessment included internal and external rotation range of motion and forward shoulder posture while maximal internal and external rotators strength were assessed with an isokinetic dynamometer in concentric and in eccentric modes (at 60°/s and 240°/s). In male players, growth and maturation induced an increase in forward shoulder posture. Absolute peak torque and bodyweight peak torque of internal and external rotators in concentric and eccentric mode were also significantly increased during with age while ER/IR concentric ratios were significantly decreased. In the female players, only absolute peak torque of internal and external rotators in concentric mode and eccentric strength of external rotators were significantly influenced by the development. Specific adaptations were found in male and female players with age and practice. The important variability in the results within the different age categories and the gender strengthens the importance of regular screening (and isokinetic evaluations) in young tennis players in order to highlight potential atypical profiles, which could have a negative influence on performance or increase the risk of injuries during the development of the player.

ISOKINETIC PROFILES AND REFERENCE VALUES OF PROFESSIONAL SOCCER PLAYERS

ABSTRACT Introduction: Isokinetics is a tool commonly used in professional soccer. There is ongoing debate among researchers as to the isokinetic reference values a player should have. Objectives: To determine the absolute peak torque (PT) and average work of professional soccer players in relation to their positions on the field, and to establish the reference values for these variables. Methods: Purposeful sampling was used to select 289 professional soccer players. The sample included 32 goalkeepers, 100 defenders, 98 midfielders, and 59 strikers. The participants were measured preseason. The players were asked to perform a 10-minute warm-up on an exercise bike, and then to perform 5 repetitions at low speed, 10 at medium speed, and 25 at high speed, with 30 to 40-s of rest between each set of repetitions. The contraction method was concentric-concentric in a dynamometer Isomed 2000. Results: The average age, weight, and height of the players was 21.9 years, 74.3 kilograms, and 1.8 meters, respectively. The goalkeepers presented higher PT at the 3 measured speeds, and the higher average work at 180°/s and 240°/s in relation to defenders and midfielders. The strikers presented higher average work at 240°/s in relation to midfielders, and higher PT in relation to the defenders and midfielders. Absolute values were shown and reference values were established. Conclusions: The goalkeepers and strikers were the players that showed the greatest differences in their favor in relation to the other positions. The peak torque values and average work were described in relation to the player's position on the field. This study resulted in the creation of a tool for health professionals working with professional soccer players, providing reference values for these players in relation to their position on the field that can be used as benchmarks, by health professionals, to optimize soccer players’ performance. Level of evidence II, Prospective comparative study.

Leg Extension Strength, Explosive Strength, Muscle Activation, and Growth as Predictors of Vertical Jump Performance in Youth Athletes

The purpose of this study was to examine the relationships among leg extension strength, explosive strength, muscle activation, and measurements of growth to predictions of vertical jump performance in youth athletes. Height, body mass, skinfolds, and quadriceps femoris muscle cross-sectional area were measured in 39 sports active children (20 females, 19 males, age = 12.52 ± 0.62 years old). Peak torque (PT), rate of torque development (RTD), rate of velocity development (RVD), and rate of electromyographic amplitude rise (RER) were measured during isometric and isokinetic leg extensions. PT, RTD, and RVD were expressed in absolute terms and normalized to body mass. Estimated jump height (JH) and peak power (PP) were assessed during static (SJ), counter-movement (CMJ), and drop (DJ) jumps. JH exhibited greater correlations with PT normalized to body mass (r = 0.387–0.758) than absolute PT (r = 0.338–0.417), whereas PP exhibited greater correlations with absolute PT (r = 0.368–0.837). Only negligible to moderate relationships existed between JH and PP across all jumps (r = 0.053–0.605). Over 50% of the variability in PP was predicted in 24 of 30 regression models with absolute muscle strength, muscle activation, and measurements of growth, while only 6 of 30 models predicted more than 50% of the variability in JH. Overall, absolute static and dynamic muscle strength, muscle activation, and growth better explained PP measured during vertical jumps than estimated JH.

The isokinetic strength profile of semi-professional soccer players according to low back pain.

Soccer as a sport has a very high injury rate and low back pain (LBP) is considered to be the most common overuse injury typically occurring in the back and spine in elite soccer players. This study aimed to investigate differences in knee muscle strength and muscle imbalances in soccer players according to lower back pain. One hundred and thirty-six male professional soccer players (20.49 ± 3.73years, 76.57 ± 8.24kg, 182.63 ± 6.73cm) volunteered for the study. The isokinetic dynamometer PrimaDOC (EASYTECH, Italy) was used to assess the hamstring and quadriceps strength at the selected speeds of 60∘/s, whereas the Roland-Morris Disability Questionnaire (RDQ) was used as a health status measure to assess physical disability caused by low back pain. A univariate analysis of variance has shown that there is a statistically significant difference among the groups divided into Absolute peak torque right knee flexors, Absolute peak torque left knee flexors, Ratio between hamstrings and quadriceps strength right leg, and Ratio between hamstrings and quadriceps strength left leg based on the RDQ scores. On the other hand, no other significant differences among the groups were found in other parametersCONCLUSION: The current study indicates that knee muscle strength variables, resulting from an isokinetic testing, have the potential to discriminate between soccer players with and without a history of low back pain. However, low back pain is a multidimensional phenomenon and knee muscle strength or imbalance alone cannot be expected to explain low back pain.

Muscle Strength Cutoff Points for Functional Independence and Wheelchair Ability in Men With Spinal Cord Injury

ObjectiveDetermine trunk and shoulder muscle strength cutoff points for functional independence and wheelchair skills, and verify the predictive capacity of relative and absolute peak torque in men with spinal cord injury (SCI). DesignCross-sectional study. SettingRehabilitation hospital setting. ParticipantsMen (N=54) with SCI were recruited and stratified into high and low paraplegia groups. InterventionsAll participants performed maximum strength tests for shoulder abduction or adduction (isokinetic) and trunk flexion or extension (isometric) to determine relative and absolute peak torque cutoff points for the Spinal Cord Independence Measure version III (SCIM-III) and Adapted Manual Wheelchair Circuit (AMWC). Main outcome measuresThe primary outcome measures were SCIM-III, AMWC-Brazil test, and strength variables (peak torques). Demographic characteristics obtained from participants’ electronic medical records were the secondary outcomes used as predictor variables of functional independence. ResultsThe best predictive model for SCIM-III (R=0.78, P≤.05) used the sum of trunk flexion and extension relative peak torque values to determine the cutoff points (1.42 N·m/kg for a score of 70). Relative shoulder abduction peak torque was used in the predictive models for AMWC outcomes: performance score (R=0.77, P≤.05, cutoff points of 0.97 N·m/kg for 300.0m) and 3-minute overground wheeling (R=0.72, P≤.05, cutoff points of 0.96 N·m/kg for 18.5s). ConclusionsRelative peak torque showed better predictive capacity compared to absolute peak torque. Cutoff points were established for relative muscle strength and could help health professionals set appropriate goals for individuals with SCI to achieve high functional independence and wheelchair ability.

Muscle torque production and kinematic properties in post-stroke patients: a pilot cross-sectional study

Stroke-related hemiplegia is an important factor influencing parameters of gait. So far, limited papers have assessed temporo- spatial capabilities and their correlations with gait parameters in the early post-stroke stage. This pilot study evaluated the temporospatial parameters of gait and assessed the maximal isometric and isokinetic torque production of the plantar flexor and dorsiflexor muscles. 15 patients with lower limb spasticity and 15 healthy controls were included. Stroke severity was assessed using the Modified Ashworth Scale and the Barthel Index. Gait cadence, gait speed, and gait cycle were assessed using inertial sensors during a Timed Up and Go test. Maximal isometric and isokinetic torque production of the ankle plantar flexor and dorsiflexor muscles were assessed using an isokinetic dynamometer device. Post-stroke patients had statistically significantly lower gait cadence than healthy participants (17%, p < 0.05). Statistically significantly lower values of vertical acceleration were also noted during a sit-to-stand movement task (42%, p < 0.05). Plantar flexion torque of the affected limb was significantly different during isometric (63%, p ≤ 0.01) and isokinetic work for 30o/s (49%, p = 0.04), 60o/s (58%, p = 0.01) and 20 °/s (53%, p = 0.01). Dorsiflexor muscles' torque production was significantly different in isometric activity (38%, p = 0.04). A statistically significant positive correlation occurred between the absolute peak torque of the dorsiflexor muscles in both static and speed phases of gait (Rs = 0.65, p = 0.04). Despite the low intensity of spasticity and early phase after stroke, differences in the muscle torque production and temporo-spatial parameters, as well as the correlations between them, were noticeable.

Obesity, but not metabolic control, is associated with muscle strength and endurance in diabetic older adults

The objective of this study is to investigate the association between muscle function, body composition, and metabolic control in adults with type 2 diabetes mellitus (DM2). Forty-eight individuals with DM2 were divided into four groups according to the severity of obesity (body mass index [BMI]: lean [LN, n = 10], overweight [OW, n = 16], obese class I [OBI, n = 15], and obese class II [OBII, n = 7]). Absolute peak torque (TQ), relative peak torque (TQ/body weight [BW]), total work (TW), and fatigue index (FI) were assessed by means of an isokinetic dynamometer during concentric knee extensor contraction. Spearman's correlation coefficients were used to estimate the association between measurements. Although OBII had higher insulin levels than both LN and OW groups, no significant differences were found between groups for TQ, TQ/BW, TW, and FI, as well as between metabolic variables and muscle measurements. There was a positive correlation between BMI and TQ (rs = .45) and resistance tests, between BMI and TQ (rs = .43), and TW (rs = .37). Metabolic variables do not correlate with muscle strength and endurance in DM2. However, severity of obesity measured by the BMI is positively associated with muscle force-generating capacity and endurance.

The relation between force production at different hip angles and functional capacity in older women

Although hip muscles are related to activities of daily living (ADLs) in older adults, there is a lack of evidence concerning the extensor–flexor hip torque–angle. A shift of the torque–angle relationship is caused by the aging process (increasing or reducing the range of motion) affecting the force production in a given muscular length during ADLs. Thus, the relationship between hip extensor–flexor muscles' force production and their association with functional capacity tests in elderly women were evaluated. Seventeen elderly women performed timed up and go, timed up and down stairs, and 30-s chair stand tests. Hip extensor–flexor isometric peak torques at 15°, 60°, 90°, and 100° (0° = full extension) were also assessed. Hip flexors produced the highest absolute and relative peak torque at a 15° angle and hip extensor muscles at 100°. A large and significant correlation (r = 0.62, p = 0.008) was observed only between absolute hip extensor peak torque at 90° and the 30-s chair stand test. When peak torque was normalized by body mass, the hip extensor–flexor muscles' peak torque obtained at all measured angles presented significant correlation with the 30-s chair stand test. The results indicate that for older women there is an optimum torque–angle for the hip flexor and extensor muscles. Furthermore, although the hip torque–angle relationship was measured under isometric contractions, there was a correlation with the 30-s chair stand test, which could indicate the presence of the isometric component during this movement.

Gender- and Muscle-Specific Responses During Fatiguing Exercise.

Hill, EC, Housh, TJ, Smith, CM, Schmidt, RJ, and Johnson, GO. Gender- and muscle-specific responses during fatiguing exercise. J Strength Cond Res 32(5): 1471-1478, 2018-The purpose of the present investigation was to examine potential gender-related differences in electromyographic (EMG) and mechanomyographic (MMG) responses during submaximal, concentric, isokinetic, forearm flexion muscle contractions. Twelve men and 12 women performed concentric peak torque trials before (pretest) and after (posttest) a fatiguing exercise bout that consisted of 50 submaximal (65% of concentric peak torque), concentric, isokinetic (60°·s), forearm flexion muscle contractions. Surface EMG and MMG signals were simultaneously recorded from the biceps brachii and brachioradialis muscles. There was a gender-related difference in the decline in absolute concentric peak torque for the men (23.8%) vs. women (18.5%) that was eliminated when covaried for differences in pretest concentric peak torque values. During the fatiguing exercise bout, EMG amplitude(AMP) increased and EMG mean power frequency (MPF) decreased for both genders and muscles. There were, however, muscle- and gender-specific increases, decreases, and no changes for MMG AMP and MMG MPF. The gender-related difference for the posttest decline in concentric peak torque was associated with differences in muscle strength which may have resulted in greater blood flow occlusion in the men than the women. The muscles with the most pronounced fatigue-induced neuromuscular responses were the biceps brachii in men and the brachioradialis in women. These findings may be related to gender differences in the usage patterns of synergistic muscles during a fatiguing task.

Comparisons of the isokinetic extension and flexion strength between light and heavy weight class Ssireum athletes

This study was conducted to compare the difference between left and right extension and flexion isokinetic muscular strength of the knee, shoulder, and trunk to compare absolute and relative strength in lightand heavy weight Ssireum athletes. Fourteen professional Ssireum athletes were divided into the light (Taebaek and Geumgang) and heavy (Halla and Baekdu) groups according to the body weight. Anthropometric measurements and isokinetic strength (knee: 60o/sec, shoulder: 30o/sec, and trunk: 30o/sec) were assessed for the absolute and relative peak torque values. Left (227.6±48.7 vs 247.0± 23.1 Nm, p=0.05) and right knee (233.7±32.0 vs 266.1±20.5, p=0.05) extension strength in absolute values were significantly different between the groups. Trunk’s extension (318.7±37.9 vs 351.2±57.4 Nm, p=0.03) and flexion (249.8±33.0 vs 302.1±42.4 Nm, p=0.03) strength also showed significant difference between the groups. Significant differences were observed for all relative values except for the left knee and trunk flexion. As for the flexion and extension strength ratios, the shoulder extension to flexion ratios of the light group was 1.32 (p=0.02) times and the heavy group was 1.01-0.98 (p=0.34). The trunk extension strength was 3.6 times that of the body weight in the light group and 2.8 times that of the body weight in the heavy group. Heavy Ssireum athletes’ absolute flexor peak torques were higher in the knee and trunk than in the light athletes. Also, the weight per weight of light athletes had relatively higher strength than the heavy athletes. In addition, the muscle strength ratio was higher in the light athletes. This study suggests that isokinetic strength is different in heavy and light weight class Ssireum athletes.

A lower extremity strength-based profile of NCAA Division I women’s basketball and gymnastics athletes: implications for knee joint injury risk assessment

ABSTRACTThis study aimed to provide a comprehensive strength-based physiological profile of women’s NCAA Division I basketball and gymnastic athletes; and to make sport-specific comparisons for various strength characteristics of the knee flexor and extensor muscles. A focus on antagonist muscle balance (hamstrings-to-quadriceps ratios, H:Q) was used to elucidate vulnerabilities in these at-risk female athletes. Fourteen NCAA Division I women’s basketball and 13 gymnastics athletes performed strength testing of the knee extensors and flexors. Outcome measures included absolute and relative (body mass normalised) peak torque (PT), rate of torque development at 50, 100, 200 ms (RTD50 etc.) and H:Q ratios of all variables. The basketball athletes had greater absolute strength for all variables except for isokinetic PT at 240°s−1 and isometric RTD50 for the knee extensors. Gymnasts showed ~20% weaker body mass relative concentric PT for the knee flexors at 60 and 120°·s−1, and decreased conventional H:Q ratios at 60 and 240°·s−1 (~15%). These findings suggest that collegiate level gymnastics athletes may be prone to increased ACL injury risk due to deficient knee flexor strength and H:Q strength imbalance. Coaches may use these findings when implementing injury prevention screening and/or for individualised strength training programming centered around an athletes strength-related deficits.