Leg Curl Machine Research Articles

Conventional Ratio of Knee Flexors and Extensors Obtained Using an Isokinetic Dynamometer and Isoinertial Devices

This study aimed to analyze the conventional ratio values of knee flexors and extensors obtained using an isokinetic dynamometer (IsoRatio), an adjusted torque test of 5RM (Ratio5RM), and absolute values of 5RM (Ratio5RML). Fifteen male volunteers (28.47 ± 5.78 years; 78.30 ± 6.59kg; 1.79 ± 0.65m) performed a 5RM test on leg extension and leg curl machines. The volunteers executed knee flexion and extension movements at 60°/s angle speed without significant differences between protocols. Regression analysis showed that the Ratio5RML correlates with the isokinetic reference ratio (r=0.649; p=0.009). The result of the paired t-test showed no significant difference between the means of the isokinetic ratio and the ratio predicted by the equation. The results of the present study suggest that the 5RM test performed with isoinertial machines can be used to estimate conventional ratio and identify imbalance between the knee flexors and extensors muscles.

Influence of Alpha-Actinin-3 R577X Polymorphism on Muscle Damage and the Inflammatory Response after an Acute Strength Training Session.

The objective of this study was to verify the influence of the ACTN3 R577X polymorphism on muscle damage and the inflammatory response after an acute strength training (ST) session. Twenty-seven healthy male individuals (age: 25 ± 4.3 years) participated in the study, including 18 RR/RX and 9 XX individuals. The participants were divided into two groups (RR/RX and XX groups) and subjected to an acute ST session, which consisted of a series of leg press, leg extension machine, and seated leg curl machine. The volunteers were instructed to perform the greatest volume of work until concentric muscle failure. Each volunteer's performance was analyzed as the load and total volume of training, and the blood concentrations of C-C motif chemokine ligand 2 (CCL2), interleukin-8 (IL-8), creatine kinase (CK), lactate dehydrogenase (LDH), myoglobin, testosterone, and cortisol were measured before the ST session and 30 min and 24 h postsession. The ACTN3 R577X polymorphism effect was observed, with increased concentrations of CCL2 (p < 0.01), IL-8 (p < 0.01), and LDH (p < 0.001) in XX individuals. There was an increase in the concentration of CK in the RR/RX group compared to XX at 24 h after training (p > 0.01). The testosterone/cortisol ratio increased more markedly in the XX group (p < 0.001). Regarding performance, the RR/RX group presented higher load and total volume values in the training exercises when compared to the XX group (p < 0.05). However, the XX group presented higher values of delayed onset muscle soreness (DOMS) than the RR/RX group (p < 0.05). The influence of ACTN3 R577X polymorphism on muscle damage and the inflammatory response was observed after an acute ST session, indicating that the RR/RX genotype shows more muscle damage and a catabolic profile due to a better performance in this activity, while the XX genotype shows more DOMS.

Exercise and Creatine Supplementation to Augment the Adaptation of Exercise Training Among Breast Cancer Survivors Completing Chemotherapy: Protocol for an Open-label Randomized Controlled Trial (the THRIVE Study).

BackgroundIn breast cancer survivors, chemotherapy-induced muscle loss has been shown to be attenuated with structured resistance exercise. Creatine supplementation can increase bioenergetics in skeletal muscle, which helps to improve overall strength and endurance and reduce muscular fatigue. Therefore, we hypothesize that adding creatinine supplementation to exercise training will accelerate improvements in strength, endurance, and bioenergetics in breast cancer survivors.ObjectiveThe primary objective is to determine the effects of combining creatine supplementation with exercise on modulating strength and physical function in breast cancer survivors by comparing these effects to those of exercise alone. The secondary objectives are to determine if creatine supplementation and exercise can increase the intramuscular storage of creatine and improve body composition by comparing this intervention to exercise alone.MethodsWe aim to test our hypothesis by conducting an open-label randomized controlled trial of 30 breast cancer survivors who have completed chemotherapy within 6 months of enrollment. Eligible participants will be equally randomized (1:1) to either a creatine and exercise group or an exercise-only group for this 12-week intervention. Individuals who are randomized to receive creatine will be initially dosed at 20 g per day for 7 days to boost the availability of creatine systemically. Thereafter, the dose will be reduced to 5 g per day for maintenance throughout the duration of the 12-week protocol. All participants will engage in 3 center-based exercise sessions, which will involve completing 3 sets of 8 to 12 repetitions on chest press, leg press, seated row, shoulder press, leg extension, and leg curl machines. The primary outcomes will include changes in strength, body composition, and physical function in breast cancer survivors. The secondary outcomes will be intramuscular concentrations of creatine and adenosine triphosphate in the vastus lateralis, midthigh cross-sectional area, and quality of life.ResultsAs of October 2021, a total of 9 patients have been enrolled into the study. No unexpected adverse events have been reported.ConclusionsCreatine is being studied as a potential agent for improving strength, endurance, and bioenergetics in breast cancer survivors following chemotherapy. The findings from our trial may have future implications for supporting breast cancer survivors in reversing the muscle loss experienced during chemotherapy and improving their physical function and quality of life.Trial RegistrationClinicalTrials.gov NCT04207359; https://clinicaltrials.gov/ct2/show/NCT04207359International Registered Report Identifier (IRRID)PRR1-10.2196/26827

Phoenix dactylifera pollen does not affect eccentric resistance exercise-induced delayed-onset muscle soreness (DOMS) in female athletes

This study is intended to investigate the effects of Phoneix Dactylifera pollen on markers of delayed-onset muscle soreness (DOMS) induced by eccentric resistance exercise in female athletes. Thirty-six female athletes were randomly selected and equally divided into 3 groups of 12 subjects, including: (1) 100 mg of P. dactylifera, (2) 200 mg of P. dactylifera, and (3) 100 mg of starch (placebo). Having received 10-day supplementation based on their groups label, all participants performed a bout of eccentric leg curl exercise by lying leg curl machine (five sets, three repetitions, each set with 110–130% one-repetition maximum, 1-min rest between sets). The blood samples were collected before and 1, 2, 3 and 4 days after the exercise. Data were analyzed using repeated measures analysis of variance (ANOVA) at a significance level of P < 0.05). Neither 100 mg nor 200 mg doses of P. dactylifera had considerably significant effects on blood levels of creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lymphocytes and neutrophils, thigh circumference, the angle of leg extension and the Sargent jump (the markers of DOMS) compared to the placebo. Eccentric resistance exercise increased markers of DOMS; however, consuming either 100 or 200 mg P. dactylifera for 10 days before the exercise had no favorable effects on the DOMS markers in female athletes.

OR-029 Effects of BCAA Plus Glucose Supplement Timing on Inflammatory Response Indicators after a Resistant Exercise

OR-029 Effects of BCAA Plus Glucose Supplement Timing on Inflammatory Response Indicators after a Resistant Exercise

Comparison of the influence of aerobic and resistance exercise of the upper and lower limb on intraocular pressure

To compare the influence of aerobic and resistance exercise on intraocular pressure (IOP). Twenty-one healthy subjects participated. Aerobic exercise was performed using a cycle ergometer, and resistance exercise was performed with a leg curl and a butterfly machine. Intraocular pressure was measured at baseline, during exercise and 10 min after. During resistance exercise, a Valsalva manoeuvre was prevented. Before aerobic exercise, the mean IOP was 18.8±2.7 mmHg. It was 16.5±2.8 after 10, 17.1±2.6 after 20 and 16.7±3.3 mmHg after 30 min of exercise. After 10 min, the IOP returned to baseline (18.8 ±2.7 mmHg). The mean IOP before resistance exercise with the leg curl machine was 17.0 (15.6-18.4; 65%Wmax ) and 16.8 (15.3-18.3) mmHg; 75%Wmax ) and did not change significantly during the experiment. The mean IOP before resistance exercise with the butterfly machine (65%Wmax ) was 16.4 (15.2-17.6) and increased to 17.2 (16.0-18.4) mmHg (p<0.05). After 10 min of recreation, it recovered to 16.3 (15.0-17.5) mmHg. At 75%Wmax , the mean baseline IOP was 16.3 (15.2-17.4) mmHg, and there were no significant changes. Aerobic exercise leads to a significant decrease of IOP. There was no influence of resistance exercise on IOP as long as a Valsalva manoeuvre was prevented.

The efficacy of frequency specific microcurrent therapy on delayed onset hamstring muscle soreness

IntroductionThe effects of frequency specific microcurrent (FSM) therapy versus sham therapy in delayed onset muscle soreness (DOMS) was studied to determine whether specific frequencies on two channels would produce better...

The efficacy of frequency specific microcurrent therapy on delayed onset muscle soreness

This study compared the effects of frequency specific microcurrent (FSM) therapy versus sham therapy in delayed onset muscle soreness (DOMS) in order to determine whether specific frequencies on two channels would produce better results than single channel single frequency microcurrent therapy which has been shown to be ineffective as compared to sham treatment in DOMS. 18 male and 17 female healthy participants (mean age 32+/-4.2 years) were recruited. Following a 15-min treadmill warm-up and 5 sub-maximal eccentric muscle contractions, participants performed 5 sets of 15 maximal voluntary eccentric muscle contractions, with a 1-min rest between sets, on a seated leg curl machine. Post-exercise, participants had one of their legs assigned to a treatment (T) regime (20 min of frequency specific microcurrent stimulation), while the participant's other leg acted as control (NT). Soreness was rated for each leg at baseline and at 24, 48 and 72 h post-exercise on a visual analogue scale (VAS), which ranged from 0 (no pain) to 10 (worst pain ever). No significant difference was noted at baseline p=1.00. Post-exercise there was a significant difference at 24h (T=1.3+/-1.0, NT=5.2+/-1.3, p=0.0005), at 48 h (T=1.2+/-1.1, NT=7.0+/-1.1, p=0.0005) and at 72 h (T=0.7+/-0.6, NT=4.0+/-1.6, p=0.0005). FSM therapy provided significant protection from DOMS at all time points tested.

The Flywheel Leg-Curl Machine: Offering Eccentric Overload for Hamstring Development

For the sole purpose of developing knee-fl exor strength, power, and size, almost any weight room or training facility is equipped with a prone, face-down leg-curl weight-stack machine. Such commercially available machines all aim at targeting and isolating the knee-fl exor muscle group. Depending on mechanical design, they differ somewhat with regard to external torque offered and hence muscle use in the desired range of motion. Given the high rate of injury reported for the fl exormuscle group in athletes relying on high horizontal speed and power 1 and the fact that leg-curl machines are frequently used both in prevention and rehabilitation of hamstring injuries, the scant information describing the basic kinematics of this exercise is rather surprising. 2,3 A novel leg-curl device (YoYo™ Technology AB, Stockholm, Sweden) uses the inertia offered by rotating fl ywheels to provide resistance. Contrary to traditional weight-stack machines, this loading feature allows for exercise with eccentric overload, as shown elsewhere for confi gurations aimed at other muscle groups. 4-6 With use of the fl ywheel leg curl, an 8-week training program improved maximal running speed and, perhaps even more important, reduced the incidence of hamstring strains in elite soccer players. 7 Unfortunately, force–velocity profi les and electromyographic (EMG) activity during concentric–eccentric actions on this device were never examined. Here, we report kinematic data in athletes performing all-out knee fl exions at different inertial settings using this particular fl ywheel confi guration.

Progressive resistance training temporarily alters hamstring torque–angle relationship

To examine the effects of eccentric and concentric progressive resistance training on muscle torque-angle relationship, 30 young adults were randomly allocated into three groups of 10, control (CTL), eccentric training (ECC) and concentric training (CON). The ECC and CON groups performed seven sessions over 3 weeks of progressive resistance training of the right hamstrings muscle, using a standard barbell and a leg curl machine. Torque-angle relationship was measured before and 4, 11 and 18 days after the end of training. Voluntary isometric torque was recorded at seven test angles, with the subject prone (20-80 degrees; 0 degrees is full extension). In the CON group, the angle of peak isometric torque increased from 46.0 +/- 5.2 degrees pre-training to 53.0 +/- 14.9 degrees on day 4 following training (P<0.05). In the ECC group, peak torque was increased over baseline on days 4 and 11 post-training, particularly at extended knee angles (P<0.05). The angle at which peak torque occurred was decreased on day 4 (50.0 +/- 8.2 degrees pre-training, 29.0 +/- 7.4 degrees on day 4) and on day 11 (both P<0.01), but was similar to baseline 18 days after training. ECC therefore induced a temporary change in torque-angle relationship.