Knee Extension Peak Torque Research Articles

Does resistance training promote enough muscular strength increases to move weak older women to better strength categories?

We compared the magnitude of muscular strength changes among older women occupants of different strength tertiles in response to progressive resistance-training (RT). Additionally, we examined the possibility of older women initially characterized as weak (occupants of the lower tertile of strength status) can achieve a higher muscular strength level to be inserted into a better category (middle or upper tertiles). The present investigation was attended by 113 physically independent older women (>60years old). Muscular strength was assessed by one-repetition maximum (1RM) tests on chest press, preacher curl, leg extension exercises, and by the isokinetic (ISOK) peak torque of knee extension and flexion at 60 and 180°/s angular velocities. The RT lasted 12weeks (3 x/week) and consisted of eight exercises for the whole body. The participants were divided into tertiles (LOWER, MIDDLE, and UPPER) according to the performance at baseline for each strength measure. After RT, the LOWER tertile showed more significant magnitude gains than the UPPER tertile to the 1RM in leg extension and preacher curl and isokinetic measurements (6.9-36.3%). A considerable number of older women increased muscular strength enough to move from LOWER to MIDDLE or UPPER tertiles. From our results, it can be inferred that older women occupants of the lower strength tertile show more significant muscular strength gains when compared to their stronger counterparts. Moreover, 12weeks of RT seem to be sufficient to transfer older women previously characterized as "weak" to a better category.

Six-minute step test for overweight and obese subjects: concurrent validity, intrarater reliability and prediction equation

The objective of this study was to evaluate the construct validation and intra-rater reproducibility of the 6-minute step test (6MST) and develop a prediction equation for the step test performance in overweight and obese individuals. A total of 35 individuals were analyzed and divided into two groups: obese/overweight and control group. The 6MST and the 6-minute walk test (6MWT) were performed on different days. An isokinetic dynamometer was used to assess the lower limb muscle strength. A moderate positive correlation between the 6MST and 6MWT performances was found in the obese/overweight group (r = 0.501; p = 0.01). Reproducibility in the obese/overweight group was excellent for both performance and cardiovascular variables (intraclass correlation coefficient (ICC)>0.8; p<0.000), with the exception of the diastolic blood pressure (DBP) immediately after, which showed very good reproducibility (ICC) = 0.79; p<0.000). The following prediction equation was developed in the obese/overweight group: number of steps climbed = 85.847 + 0.482 x (peak knee extension torque). The 6MST is a valid, reproducible and viable alternative to assess functional exercise capacity in obese and overweight young people. The results showed that the lower limb muscle strength is able to predict performance on the 6MST.Keywords: validation study, reproducibility of results, obesity, exercise test, muscle strength.

Integration of High Velocity Elastic Band for Hamstring Training in Pre-Season Routine of Football Players

Background. A need for other methods of hamstring strengthening are thus warranted with the main aim of reducing the risk of injury during the subsequent intense athletic activities. The study aimed to examine changes in hamstring strength in response to high velocity elastic band training when incorporated into regular training routine of football players.
 Methods. Research participants were professional top level football players (age 23.1 ± 5.7 years; weight 77.2 ± 7.7 kg, training experience 14.1 ± 5.8 years). In the pre-season, in addition to their routine training, the experimental group performed hamstring curls at maximal intensity while lying prone three times per week for five weeks, while control group continued their routine training. Concentric knee torque at 60°/s and 180°/s angular velocities, countermovement jump height, 30m sprint running performance from standing and flying start, and knee flexion-extension movement frequency were measured before and after the 5 weeks of training.
 Results. Hamstring curl frequency during lying prone increase by 10.5 % (p < .05) in the experimental group and did not change in the control group. Peak torque for knee flexion and knee extension, jump height and sprint running performance did not change significantly in any group (p > .05).
 Conclusion. High velocity elastic band training incorporated into regular pre-season routine is beneficial for football players to increase their knee extension-flexion maximal movement frequency with no evident effects on strength, jump and sprint running performance. Results might be related with concurrent training during preparatory training phase of the pre-season when several physical capacities are being developed simultaneously.
 Keywords: high speed movements; peak torque; sprint performance; prevention of hamstring injuries; knee flexion strength.

Single-leg hop can result in higher limb symmetry index than isokinetic strength and single-leg vertical jump following anterior cruciate ligament reconstruction

BackgroundA single-leg vertical jump height (SLVJ) may reflect knee extension strength more than a single-leg hop for distance (SLH). This study aimed to examine the relationships between the isokinetic knee extension torque, SLH, and SLVJ after anterior cruciate ligament reconstruction (ACLR). MethodsForty-four patients post-ACLR (median 12.0 months) participated in the study. The isokinetic knee extension peak torque at 60°/s and 180°/s (Ext 60, 180), SLH, and SLVJ were measured. The limb symmetry index (LSI) was calculated as the ratio of the operated side to the unoperated side. ResultsThere were moderate-to-strong positive correlations between isokinetic knee extension torque and both SLH (r = 0.72–0.77, P < 0.001) and SLVJ (r = 0.73–0.79, P < 0.001). Significant side-to-side differences in isokinetic knee extension torque and SLVJ between the operated and unoperated sides were found (P < 0.05), but not for SLH (P = 0.065). The results of the analysis of variance (ANOVA) and post hoc analyses showed that the LSI of SLH (98.2%) was higher than that of the LSI of Ext 180 and SLVJ (P < 0.05). Fisher's exact test showed a significant relationship between the LSI of Ext 180 and that of SLVJ (cut-off 85%; P = 0.041). No patients had LSI < 85% in SLH. ConclusionsEven though SLH asymmetry improved approximately 12 months after ACLR, the asymmetry of isokinetic knee extension torque and SLVJ remained. The LSI of SLVJ could be an indicator of the recovery of isokinetic knee extension torque.

Effect of High-frequency Diathermy on Hamstring Tightness

Background: The hamstring is a muscle that crosses two joints, that is the hip and knee, and its flexibility is an important indicator of physical health in its role in many activities of daily living such as sitting, walking, and running. Limited range of motion (ROM) due to hamstring tightness is strongly related to back pain and malfunction of the hip joint. High-frequency diathermy (HFD) therapy is known to be effective in relaxing the muscle and increasing ROM. Objects: To investigate the effects of HFD on active knee extension ROM and hamstring tone and stiffness in participants with hamstring tightness. Methods: Twenty-four participants with hamstring tightness were recruited, and the operational definition of hamstring tightness in this study was active knee extension ROM of below 160° at 90° hip flexion in the supine position. HFD was applied to the hamstring for 15 minutes using the WINBACK device. All participants were examined before and after the intervention, and the results were analyzed using a paired t-test. The outcome measures included knee extension ROM, the viscoelastic property of the hamstring, and peak torque for passive knee extension. Results: The active knee extension ROM significantly increased from 138.8° ± 9.9° (mean ± standard deviation) to 143.9° ± 10.4° after the intervention (p < 0.05), while viscoelastic property of the hamstring significantly decreased (p < 0.05). Also, the peak torque for knee extension significantly decreased (p < 0.05). Conclusion: Application of HFD for 15 minutes to tight hamstrings immediately improves the active ROM and reduces the tone, stiffness, and elasticity of the muscle. However, further experiments are required to examine the long-term effects of HFD on hamstring tightness including pain reduction, postural improvement around the pelvis and lower extremities, and enhanced functional movement.

A Randomized Double-Blind Placebo-Controlled Pilot Trial on the Effects of Testosterone Undecanoate Plus Dutasteride or Placebo on Muscle Strength, Body Composition, and Metabolic Profile in Transmen

BackgroundWhile the effects of androgens on muscle are well described in hypogonadal men, literature is still scarce on muscular strength or size variations in transmen; in this population there are no data regarding the relative effect of testosterone (T) and its metabolite dihydrotestosterone on muscle. AimOur primary objective was to compare the effects on muscle strength of 54-week administration of testosterone undecanoate (TU) combined with the 5α-reductase inhibitor dutasteride (DT) or placebo (PL). Secondary outcomes included evaluation of body composition, bone, cutaneous androgenic effects, and metabolic variations. MethodsIn this randomized, double-blind PL-controlled pilot trial, 16 ovariectomized transmen were randomized to receive TU 1,000 mg IM at week 0, 6, 18, 30, 42 plus a PL pill orally daily (TU + PL, n = 7) or plus DT 5 mg/d (TU + DT, n = 7). OutcomesAt week 0 and 54 the following parameters were evaluated: isokinetic knee extension and flexion peak torque and handgrip strength, body composition, and bone mineral density, biochemical, hematological, and hormonal parameters. ResultsHandgrip and lower limb strength increased significantly in both groups with no differences between the 2 groups. Fat mass decreased and lean mass increased significantly similarly in both groups. Metabolic parameters remained stable in the 2 groups except for high-density lipoprotein cholesterol that was reduced in both groups. Hepatic and renal function remained normal in both groups and no major adverse effects were registered in either group. Clinical ImplicationsThese results may be particularly relevant for transmen experiencing cutaneous androgenic adverse events such as acne and androgenetic alopecia and in light of the development of non-5α-reduced androgens. Strengths & LimitationsThe strength of this study was the randomized, double-blind PL-controlled design, while the small number of subjects was definitely the biggest limitation. ConclusionFor the first time we demonstrated that the addition of DT does not impair the anabolic effects of T on muscles in transmen previously exposed to T, supporting the hypothesis that the conversion in dihydrotestosterone is not essential for this role.Gava G, Armillotta F, Pillastrini P, et al. A Randomized Double-Blind Placebo-Controlled Pilot Trial on the Effects of Testosterone Undecanoate Plus Dutasteride or Placebo on Muscle Strength, Body Composition, and Metabolic Profile in Transmen. J Sex Med 2021;XX:XXX–XXX.

Obese Youth Demonstrate Altered Landing Knee Mechanics Unrelated to Lower-Extremity Peak Torque When Compared With Healthy Weight Youth

Obese (OB) youth demonstrate altered knee mechanics and worse lower-extremity performance compared with healthy weight (HW) youth. Our objectives were to compare sagittal plane knee landing mechanics between OB and HW youth and to examine the associations of knee and hip extension peak torque with landing mechanics in OB youth. Twenty-four OB and 24 age- and sex-matched HW youth participated. Peak torque was measured and normalized to leg lean mass. Peak knee flexion angle and peak internal knee extension moment were measured during a single-leg hop landing. Paired t tests, Pearson correlation coefficients, and Bonferroni corrections were used. OB youth demonstrated worse performance and lower knee extension (OB: 12.76 [1.38], HW: 14.03 [2.08], P = .03) and hip extension (OB: 8.59 [3.13], HW: 11.10 [2.89], P = .005) peak torque. Furthermore, OB youth demonstrated lower peak knee flexion angles (OB: 48.89 [45.41 to 52.37], HW: 56.07 [52.59 to 59.55], P = .02) and knee extension moments (OB: -1.73 [-1.89 to -1.57], HW: -2.21 [-2.37 to -2.05], P = .0001) during landing compared with HW youth. Peak torque measures were not correlated with peak knee flexion angle nor internal knee extension moment during landing in either group (P > .01). OB youth demonstrated altered landing mechanics compared with HW youth. However, no associations among peak torque measurements and knee landing mechanics were present.

Exercise associated or not to the intake of Eurycoma longifolia improves strength and cardiorespiratory fitness in men with androgen deficiency

This study aims to analyze the effects of a concurrent training (CT) associated with Eurycoma longifolia (EL) supplementation on the muscle strength, cardiorespiratory fitness, and symptomatology score of men with the androgen deficiency of aging male (ADAM). Forty-five subjects (47.6 ± 5.2 years) were included in the study. The randomized, double-blinded, placebo controlled clinical trial lasted for 6 months. Participants were randomized into four groups, control (C; n = 12); EL (n = 11); CT (n = 11); and CT + EL (n = 11). Along this period, the isokinetic peak torque of the knee extensors increased in the CT (14%) and CT + EL (17%) groups (p = 0.040; p = 0.006, respectively), while the isokinetic peak torque of knee flexion increased in the CT + EL group only (p < 0.05). For all participants, testosterone levels were correlated with isokinetic peak torque of knee extension (r = 0.517, p = 0.001) and flexion (r = 0.362, p = 0.028). Subjects of the CT (27.3%) and CT + EL (36.1%) groups decreased the symptomatology of ADAM (p = 0.005). This study demonstrated the benefits of CT and EL consumption as a non-pharmacological treatment for ADAM.

Unique Characteristics of Quadriceps Muscle Morphology and Function in Older Tennis Players.

We investigated the quadriceps muscle size and quantitative characteristics in older tennis players. Thirty-eight senior tennis players (70.8 ± 5.3years) and 38 controls (71.6 ± 5.1years) were included. To measure the muscle size and quality, we measured muscle thickness in the rectus femoris (RF), vastus lateralis, and vastus intermedius, and muscle echo intensity in the RF and vastus lateralis using B-mode transverse ultrasound, respectively. We measured knee extension peak torque for muscle function. Muscle thickness in the RF, vastus lateralis, and vastus intermedius were significantly larger in tennis players than in controls. Tennis players had a lower echo intensity in RF and a higher knee extension peak torque compared to controls. Stepwise multiple linear regression analysis implied that echo intensity and muscle thickness were predictors of knee extension peak torque. Higher muscle quality contributes to a higher knee extension peak torque in tennis players. Playing tennis may prevent age-related muscle atrophy and maintain muscle quality in older individuals.

Impaired muscle capacity of the hip and knee in individuals with isolated patellofemoral osteoarthritis: a cross-sectional study.

Aims:The aims of this study were to compare the capacity of the knee and hip muscles between individuals with and without isolated patellofemoral osteoarthritis (PFOA) and to evaluate the impact of PFOA on pain, stiffness, and physical function.Methods:This cross-sectional study evaluated muscle capacity of the hip and knee using an isokinetic dynamometer. The isokinetic variables used in the statistical analysis were peak torque, total work, and average power. Pain, stiffness, and physical function were assessed using questionnaires.Results:A total of 26 individuals participated in the study (13 with PFOA and 13 controls). The PFOA group exhibited lower peak torque, total work, and average power for knee extension and flexion in the concentric mode (p ⩽ 0.01) as well as lower peak torque and total work for knee extension (p ⩽ 0.005) and lower total work for knee flexion (p = 0.05) in the eccentric mode. The PFOA group exhibited lower peak torque of the extensor, abductor, adductor, and internal rotator muscles of the hip (p ⩽ 0.05), less total work of the abductor and adductor muscles (p ⩽ 0.04), and lower average power of eccentric adduction of the hip (p = 0.01) compared with the healthy controls. Compared with the control group, the PFOA group had a higher level of pain, stiffness, and compromised physical functioning self-reported (p ⩽ 0.005).Conclusion:Participants with PFOA exhibited impairments regarding muscle capacity of the hip and knee, higher level of pain and stiffness as well as compromised physical functioning in comparison with healthy controls.

Effects of branched-chain amino acid supplement on knee peak torque and indicators of muscle damage following isokinetic exercise-induced delayed onset muscle soreness

[Purpose] This study aimed to investigate the effects of branched-chain amino acid (BCAA) supplement on delayed onset muscle soreness (DOMS) by analyzing the maximum muscle strength and indicators of muscle damage.[Methods] Twelve men with majors in physical education were assigned to the BCAA group and placebo group in a double-blinded design, and repeated measurements were conducted. DOMS was induced with an isokinetic exercise. Following BCAA administration, the changes in the knee extension peak torque, flexion peak torque, aspartate aminotransferase (AST), creatine kinase (CK), and lactate dehydrogenase (LDH) concentrations were analyzed. The maximum knee muscle strength was measured at the baseline (pre-D0) following BCAA administration for 5 days before exercise (-D5, -4D, -3D, -2D, -1D). In contrast, the post-treatment measurements (D3) were recorded after BCAA administration for 3 days (post-D0, D1, D2). Blood samples were obtained before (pre-D0), immediately after (post-D0), 24 h (D1), 48 h (D2), and 72 h (D3) after the exercise to analyze the indicators of muscle strength. BCAA was administered twice daily for 8 days (5 days and 3 days before inducing DOMS and during the experimental period, respectively).[Results] There was no difference in the flexion peak torque between the groups. However, the BCAA group showed a significantly higher extension peak torque at D3 (second isokinetic exercise), compared to the placebo group (p<.05). There was no difference in AST changes between the groups. Nonetheless, the CK and LDH were significantly reduced in the BCAA group, compared to the placebo group. There was no correlation between the extension peak torque and flexion peak torque. However, the CK and LDH increased proportionately in DOMS. Moreover, their concentrations significantly increased with a decreasing peak torque (p<.01).[Conclusion] An exercise-induced DOMS results in a decrease in the peak torque and a proportional increase in the CK and LDH concentrations. Moreover, the administration of BCAA inhibits the reduction of the extension peak torque and elevation of CK and LDH concentrations. Therefore, BCAA might be administered as a supplement to maintain the muscle strength and prevent muscle damage during vigorous exercises that may induce DOMS in sports settings.

Determining the number of repetitions to establish isokinetic knee evaluation protocols specific to angular velocities of 60°/second and 180°/second

IntroductionThis study aims to develop a standard number of repetition at angular velocities of 60°/sec and 180°/sec and define the difference of number of repetitions between genders. MethodOne hundred ninety-six athletes (judo, volleyball, Greco-Roman wrestling, runners, and gymnastics) were involved. Concentric-concentric isokinetic muscle strength of the knee flexor-extensor muscles of the athletes were performed with an ISOMED 2000 isokinetic dynamometer. The evaluation test protocol consisted of 10 repetition of knee flexion-extension at 60°/sec and 30 repetitions at 180°/sec. ResultsAthletes performed with maximal knee flexion strength at their second and third trial at 60°/sec and third-forth trial at 180°/sec. It was found that 2 repetitions and 2–3 repetitions were needed for knee extension peak torque at 60°/sec and 180°/sec respectively. The difference between the genders was significant at 60°/sec for knee flexion and extension on the dominant side; at 180°/sec for knee extension on the dominant and non-dominant side. It was determined that 3 repetitions for 60°/sec, 4 repetitions for 180°/sec were enough to determine peak torque values. DiscussionOptimal number of repetitions is crucial so that athletes could have the opportunity to reach maximal strength without unnecessary workload or waste of time. ConclusionsProtocols involving 3 repetitions for 60°/sec, 4 repetitions for 180°/sec were enough to determine peak torque values. Gender of athletes should be considered when establishing isokinetic knee evaluation protocols.

Abstract 14927: Effects of Low Intensity Resistance Exercise Under Kaatsu Condition on Skeletal Muscle Size and Its Safety inCardiovascular Surgery Patients

Introduction: Surgery for cardiovascular disease is often accompanied by sarcopenia and physical frailty, and improvement of muscle mass, muscle strength, and ADL, is often difficult only with cardiac rehabilitation using aerobic exercise. The resistance training under moderately restricted muscle blood flow, named as KAATSU, induces muscle hypertrophy and strengthens muscle through low intensity exercise. However, it remains uninvestigated whether KAATSU resistance training using low intensity load (KAATSU-RE) increases muscle strength, and induces hypertrophy in patients early after cardiovascular surgery. Hypothesis: To investigate the effects of KAATSU-RE on skeletal muscle strength, hypertrophy and its safety in patients early after cardiovascular surgery. Methods: Nine patients early after cardiac surgery were included in this study (seven males, age 54 ± 18 years, BMI 23.0 ± 3.7 kg/m 2 , AVR 5 cases, MVP 3, Bentall operation 1). The patients performed leg extension exercise (20~30% 1RM) under KAATSU condition two times/week for three months. Training started after 200 m walking early after the operation. Skeletal muscle mass index (SMI) was evaluated using bioelectrical impedance analysis (BIA). The anterior mid-thigh thickness (MTH) was measured using B mode transverse ultrasound images. Physical functions (isometric knee extension peak torque, handgrip strength, and walking speed) were also measured at three points, i.e. baseline (before operation), ~7 days early after operation, and ~3 months after the training. Results: SMI and MTH decreased significantly from 7 ± 1.1, and 2.5 ± 0.4 cm preoperatively to 6.7 ± 1.0, and 2.2 ± 0.3 cm approximately 1 week after surgery. Approximately 3 months after the training, they increased significantly to 7.6 ± 0.8 and 3 ± 0.4 cm. During the rehabilitation period, hemodynamic deterioration and side effects including subcutaneous hemorrhage were not observed, and all the patients completely finished the study. Conclusions: These results suggest that KAATSU training safely increased muscle mass in patients in the early perioperative period of cardiovascular surgery. KAATSU training appears to be a promising and effective method for cardiac rehabilitation in patients with cardiovascular surgery.

Reproducibility of isokinetic knee testing using the novel isokinetic SMM iMoment dynamometer.

Isokinetic dynamometry is the gold standard for testing maximal strength in elite sport and rehabilitation settings. To be clinically useful, such tests should be valid and reliable. Despite some evidence regarding the relative test vs retest reliability of knee dynamometry, there is still a paucity of research regarding the absolute reliability parameters. The purpose of this study was to assess the absolute and relative intra-device reproducibility of isokinetic knee flexion and extension using the novel SMM iMoment dynamometer. A total of 19 participants (13 males and 6 females, aged 24 (2) years, height 178 (9) cm and weight 76 (11) kg) performed two identical knee isokinetic tests with at least a week of rest between measurements. Peak torque of knee extension and flexion were determined at 60°/s. Moderate (0.892) to excellent (0.988) relative reliability using the intraclass correlation coefficient (ICC) was obtained for peak knee torque. Absolute reliability assessed with a standard error of measurement (SEM %) was low, ranging from 2.54% to 6.93%, whereas the smallest real difference (SRD %) was moderate, ranging from 7.04% to 19.22%. Furthermore, there were no significant correlations between means and differences of two measurements, and Bland-Altman plots also showed no signs of heteroscedasticity. Our measurement protocol established the moderate to excellent reliability of the novel SMM iMoment isokinetic dynamometer. Therefore, this dynamometer can be applied in sport rehabilitation settings to measure maximal knee strength.

Long-term Effects of Calcium β-Hydroxy-β-Methylbutyrate and Vitamin D3 Supplementation on Muscular Function in Older Adults With and Without Resistance Training: A Randomized, Double-blind, Controlled Study.

The primary aim of this study was to determine whether supplementation with calcium β-hydroxy-β-methylbutyrate (HMB) and vitamin D3 (D) would enhance muscle function and strength in older adults. Older adults over 60 years of age with insufficient circulating 25-hydroxy-vitamin D (25OH-D) levels were enrolled in a double-blinded controlled 12-month study. Study participants were randomly assigned to treatments consisting of: (a) Control + no exercise, (b) HMB+D + no exercise, (c) Control + exercise, and (d) HMB+D + exercise. The study evaluated 117 participants via multiple measurements over the 12 months that included body composition, strength, functionality, and questionnaires. HMB+D had a significant benefit on lean body mass within the nonexercise group at 6 months (0.44 ± 0.27 kg, HMB+D vs −0.33 ± 0.28 kg, control, p < .05). In nonexercisers, improvement in knee extension peak torque (60°/s) was significantly greater in HMB+D-supplemented participants than in the nonsupplemented group (p = .04) at 3 months, 10.9 ± 5.7 Nm and −5.2 ± 5.9 Nm, respectively. A composite functional index, integrating changes in handgrip, Get Up, and Get Up and Go measurements, was developed. HMB+D + no exercise resulted in significant increases in the functional index compared with those observed in the control + no exercise group at 3 (p = .03), 6 (p = .04), and 12 months (p = .04). Supplementation with HMB+D did not further improve the functional index within the exercising group. This study demonstrated the potential of HMB and vitamin D3 supplementation to enhance muscle strength and physical functionality in older adults, even in individuals not engaged in an exercise training program.

Relation of Musculoskeletal Strength and Function to Postural Stability in Ambulatory Adults With Cerebral Palsy

ObjectiveTo understand the relation of musculoskeletal strength and function to postural stability in ambulatory adults with cerebral palsy (CP) who have already developed muscle atrophy and osteoporosis. DesignTwo independent group comparison of adults with CP and those without it. SettingLaboratory study. ParticipantsThirteen adults with CP with sex (9 women: 4 men), age (21-62y), and Gross Motor Function Classification System I-III, and 13 sex-, age-, and body-weight-matched control participants completed our study (N=26). InterventionNot applicable. Main Outcome MeasureBone mineral density (BMD), structural or geometrical deformities (at the proximal region of the femur at the hip joint), and maximal muscular strength (forearm and thigh) were measured. The primary outcome measure was postural stability (balance measured using an automated balance system and a Berg Balance Test). ResultsFemoral BMD was significantly lower in the CP group compared to the control group, whereas BMD at lumbar and forearm regions was similar between groups. Geometrical angles, lengths, and diameters at the proximal femur were significantly lower in the CP group. There was a direct relation between BMD in the femoral neck and knee extension peak torque in the control group with no relation in the CP group. Although the control group did not show a relation between muscular strength and balance test, the CP group showed a significant linear relation among improving postural stability with greater levels of muscular strength. ConclusionThere were structural differences at the proximal femur and muscular weakness in adults with CP. In adults with CP, balance appears to be more influenced by structural alterations at the femur than muscular strength compared to the control group.

Quadriceps Strength And Rate Of Torque Development Are Associated With Countermovement Jump Knee Kinetics Post-aclr

Quadriceps neuromuscular dysfunction is ubiquitous after anterior cruciate ligament reconstruction (ACLR) and can impair knee function during athletic activities. While peak quadriceps strength is often measured, time-dependent metrics such as rate of torque development may be important to sports performance. PURPOSE: To determine the relationships between quadriceps strength, rate of torque development, time since surgery, and knee joint kinetics during jumping in collegiate athletes up to 2 years post-ACLR. METHODS: 31 Division I athletes (age 20.3±1.3, BMI 26.1±3.9 kg/m2, 17 female) performed countermovement jumps (CMJ) on force plates while whole body kinematics were recorded and completed maximal and rapid voluntary isometric knee extension (KE) contractions. Sagittal plane KE impulses were computed for concentric (CON) and landing (LAND) CMJ phases; KE peak torque (PT) and rate of torque development from 20-80% of peak torque (RTD) were extracted from isometric KE efforts. Limb symmetry indices (LSI) were computed and clinically relevant cutoffs of 90% LSI were investigated. A mixed effects model accounted for repeated measurements and assessed the relationships of PT, RTD, and time from surgery with CON and LAND. All possible pairwise interactions were tested. RESULTS: Among 31 athletes, 81 tests were completed 4-24 months post-surgery. PT and RTD were significantly correlated with CON (PT: p=.001, RTD: p=.044) and LAND (PT: p=.009, RTD: p=.008). No significant pairwise interactions between PT, RTD, and time from surgery were detected. Among 24 instances of PT LSI ≥ 90%, mean CON and LAND LSI were 87.3% and 94.2%, respectively. In comparison, among 15 occurrences of RTD LSI ≥ 90%, mean CON and LAND LSI were 93.0% and 102.2%. Among the 22 assessments completed ≥ 1 year post-surgery, mean CON and LAND LSI were 82.4%, and 83.3%, respectively. However, when CON and LAND LSI were ≥ 90%, mean PT was 94.5-94.7% and mean RTD was 85.1-85.3%. CONCLUSIONS: Both peak and rapid knee extensor torque development are strongly associated with symmetrical sagittal plane CMJ knee mechanics. CMJ knee kinetic asymmetries did not resolve over time, independent from quadriceps function. Restoring maximal and rapid quadriceps torque capacity appears to be an important step in recovering symmetrical CMJ mechanics post-ACLR.

The Use of Recombinant Human Growth Hormone to Protect Against Muscle Weakness in Patients Undergoing Anterior Cruciate Ligament Reconstruction: A Pilot, Randomized Placebo-Controlled Trial

Background: Anterior cruciate ligament (ACL) tears are common knee injuries. Despite undergoing extensive rehabilitation after ACL reconstruction (ACLR), many patients have persistent quadriceps muscle weakness that limits their successful return to play and are also at an increased risk of developing knee osteoarthritis (OA). Human growth hormone (HGH) has been shown to prevent muscle atrophy and weakness in various models of disuse and disease but has not been evaluated in patients undergoing ACLR. Hypothesis: Compared with placebo treatment, a 6-week perioperative treatment course of HGH would protect against muscle atrophy and weakness in patients undergoing ACLR. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: A total of 19 male patients (aged 18-35 years) scheduled to undergo ACLR were randomly assigned to the placebo (n = 9) or HGH (n = 10) group. Patients began placebo or HGH treatment twice daily 1 week before surgery and continued through 5 weeks after surgery. Knee muscle strength and volume, patient-reported outcome scores, and circulating biomarkers were measured at several time points through 6 months after surgery. Mixed-effects models were used to evaluate differences between treatment groups and time points, and as this was a pilot study, significance was set at P < .10. The Cohen d was calculated to determine the effect size. Results: HGH was well-tolerated, and no differences in adverse events between the groups were observed. The HGH group had a 2.1-fold increase in circulating insulin-like growth factor 1 over the course of the treatment period (P < .05; d = 2.93). The primary outcome measure was knee extension strength, and HGH treatment increased normalized peak isokinetic knee extension torque by 29% compared with the placebo group (P = .05; d = 0.80). Matrix metalloproteinase–3 (MMP3), which was used as an indirect biomarker of cartilage degradation, was 36% lower in the HGH group (P = .05; d = –1.34). HGH did not appear to be associated with changes in muscle volume or patient-reported outcome scores. Conclusion: HGH improved quadriceps strength and reduced MMP3 levels in patients undergoing ACLR. On the basis of this pilot study, further trials to more comprehensively evaluate the ability of HGH to improve muscle function and potentially protect against OA in patients undergoing ACLR are warranted. Registration: NCT02420353 (ClinicalTrials.gov identifier)

Associations between the serum levels of selected bone turnover markers and biological traits in nursing home women aged 80+ without inflammation. A pilot study

Bone turnover markers (BTM) reflect the status of bone remodeling processes responsible for bone mineral density. The existing body of evidence that osseous tissue can interact with many other body tissues and organs suggests that the cross-talks can lead to different relationships. The biological traits associated with BTMs have not been thoroughly studied in the elderly despite bone turnover being known to increase with age. To determine whether the C-terminal crosslinking telopeptides of type I collagen (CTXI) and the serum levels of total (TAP) and bone-specific (BAP) alkaline phosphatase are associated with the biological traits in nursing home women aged 80-92years without inflammation and, if so, to indicate the best predictors of these BTM's blood concentrations. A group of 64 female volunteers aged 80years and older, the residents of nursing homes, were screened for the study. Fifty two women were ineligible as they met the exclusion criteria. As a result, the study group consisted of 12 participants (85.1±3.9years; 58.1±8.7kg; 1.52±0.06m), all having blood C-reactive protein (CRP) levels below 3mg/l. Also assessed were the participants' morphology, glucose and insulin levels, lipid profiles, CTXI, TAP, and BAP. Other measured parameters included body composition, resting heart rate and arterial blood pressure, isometric knee extension peak torque (IKEPT), and walking capacity (6-min walk test). The statistical analysis was performed using Pearson's correlation coefficients, the Benjamini-Hochberg procedure, and a stepwise multiple regression analysis with backward elimination. Inverse correlations were found between CTX-I and hemoglobin concentration (HGB) (r=-0.680; p=.015), red blood cells count (RBC) (r=-0.664; p=.019), fat-free mass (r=-0.633; p=.027), body weight (r=-0.589; p=.044), and total cholesterol (r=-0.581; p=.048). The multiple regression analysis of CTX-I showed that body weight was the only independent variable that was statistically significant (r2=0.346; p<.05; SEE=0.347ng/ml). BAP was positively correlated with double product (DP) (r=0.742; p=.006), RBC (r=0.650; p=.022), HGB (r=0.637; p=.026), mean arterial pressure (MAP) (r=0.622; p=.031), diastolic blood pressure (DBP) (r=0.612; p=.034), body height (r=0.603; p=.038), IKEPT (r=0.565; p=.056), and systolic blood pressure (SBP) (r=0.538; p=.071). BAP, a dependent variable, was the most closely correlated with DP (r2=0.550; p<.01; SEE=9.161U/l). TAP was also significantly associated with DP (r=0.775; p=.003), with the association being stronger than between BAP and DP (r2=0.600; p<.01; SEE=1000.5 beats/min*mmHg). In relatively healthy the oldest-old nursing home women without inflammation, total body weight was the best predictor of bone resorption shown by the CTX-I concentration, whereas the rate pressure product (DP) turned out to best predict osteoblastic activity determinable from serum alkaline phosphatase activity. The results of the study suggest that the activity of serum TAP and BAP can be enhanced by different mechanisms.

Adaptations to strength training differ between endurance-trained and untrained women

PurposeThe purpose of this study was to investigate if endurance athletes, sustaining their normal endurance training, experience attenuated adaptations to strength training compared to untrained individuals.MethodsEleven non-strength-trained female endurance athletes (E + S) added 11 weeks of strength training to their normal endurance training (5.1 ± 1.1 h per week), and 10 untrained women (S) performed the same strength training without any endurance training. The strength training consisted of four leg exercises [3 × 4 − 10 repetition maximum (RM)], performed twice a week for 11 weeks.ResultsE + S and S displayed similar increases in 1RM one-legged leg press (E + S 39 ± 19%, S 42 ± 17%, p < 0.05), maximal isometric torque in knee extension (E + S 12 ± 11%, S 8 ± 10%, p < 0.05) and lean mass in the legs (E + S 3 ± 4%, S 3 ± 3%, p < 0.05). However, S displayed superior increases in peak torque in knee extension at an angular velocity of 240° sec−1 (E + S 8 ± 5%, S 15 ± 7%, p < 0.05) and maximal squat jump height (E + S 8 ± 6%, S 14 ± 7%, p < 0.05).ConclusionsIn this study, concurrent training did not impair the adaptations in the ability to develop force at low contraction velocities or muscle hypertrophy. However, concurrent training attenuated strength training-associated changes in the ability to develop force at higher muscular contraction velocities.