Extensor Peak Torque Research Articles

Balance Exercises Circuit improves muscle strength, balance, and functional performance in older women.

This study introduces the Balance Exercises Circuit (BEC) and examines its effects on muscle strength and power, balance, and functional performance in older women. Thirty-five women aged 60+ (mean age=69.31, SD=7.35) were assigned to either a balance exercises group (BG, n=14) that underwent 50-min sessions twice weekly, of a 12-week BEC program, or a wait-list control group (CG, n=21). Outcome measures were knee extensor peak torque (PT), rate of force development (RFD), balance, Timed Up & Go (TUG), 30-s chair stand, and 6-min walk tests, assessed at baseline and 12weeks. Twenty-three participants completed follow-up assessments. Mixed analysis of variance models examined differences in outcomes. The BG displayed improvements in all measures at follow-up and significantly improved compared with CG on, isokinetic PT60, PT180 (p=0.02), RFD (p<0.05), balance with eyes closed (p values range .02 to <.01) and TUG (p=0.03), all with medium effect sizes. No changes in outcome measures were observed in the CG. BEC improved strength, power, balance, and functionality in older women. The BEC warrants further investigation as a fall prevention intervention.

Measurement of maximal isometric torque and muscle quality of the knee extensors and flexors in healthy 50- to 70-year-old women.

Muscle quality is defined as strength per unit muscle mass. The aim of this study was to measure the maximal voluntary isometric torque of the knee extensor and flexor muscle groups in healthy older women and to develop an index of muscle quality based on the combined knee extensor and flexor torque per unit lean tissue mass (LTM) of the upper leg. One hundred and thirty-six healthy 50- to 70-year-old women completed an initial measurement of isometric peak torque of the knee extensors and flexors (Con-Trex MJ; CMV AG, Dubendorf, Switzerland) that was repeated 7days later. Subsequently, 131 women returned for whole- and regional-body composition analysis (iDXA™ ; GE Healthcare, Chalfont St Giles, Buckinghamshire, UK). Isometric peak torque demonstrated excellent within-assessment reliability for both the knee extensors and flexors (ICC range: 0·991-1·000). Test-retest reliability was lower (ICC range: 0·777-0·828) with an observed mean increase of 5% in peak torque [6·2 (17·2)Nm] on the second day of assessment (P<0·001). The relative mean decrease in combined isometric peak torque (-12·2%; P=0·001) was double that of the relative, non-significant, median difference in upper leg LTM (-5·3%; P=0·102) between those in the 5th and 6th decade. The majority of difference in peak isometric torque came from the knee extensors (15·1Nm, P<0·001 versus 2·4Nm, P=0·234). Isometric peak torque normalized for upper leg LTM (muscle quality) was 8% lower between decades (P=0·029). These findings suggest strength per unit tissue may provide a better indication of age-related differences in muscle quality prior to change in LTM.

Effects of sustained release growth hormone treatment during the rehabilitation of adult severe burn survivors

ObjectivesThe catabolic phase following burn injuries increases caloric imbalance and results in substantial weight loss because of hypermetabolism; energy expenditures as high as twice the normal limit have been documented during the first 3weeks. Furthermore, the wound size and healing duration seem to be related to the length of stay in the intensive care unit, which results in the loss of muscle mass, the so-called sarcopenia; weakness; and physical frailty. Possible therapeutic strategies include exercises, use of anabolic steroids, or replacement with human growth hormone (hGH). To determine the clinical effects of hGH on sarcopenia after burn injuries, we compared patients who received subcutaneous hGH injections during rehabilitation with control patients who received placebo treatment. MethodsA total of 33 patients with third degree burn injuries covering a total body surface area of >20% were randomly divided into a test group (n=18), which received 2-mg injections of sustained release hGH (SR-hGH) weekly for 3months during rehabilitation, and a control group (n=15), which followed the same rehabilitation protocol with placebo injections. Muscular strength, cardiopulmonary function, body composition, and body weight were measured at baseline and 1 and 3months after SR-hGH or placebo administration. ResultsThe mean age of patients was 37.67±7.64years in the SR-hGH group and 37.22±8.19years in the control group, while the interval between injury and SR-hGH or placebo injection was 123.7±53.6 and 126.6±43.5days, respectively. The oxygen consumption at the lactate threshold, maximum oxygen consumption, lean body mass, knee extensor peak torque, and insulin-like growth factor 1 (IGF-1) and adiponectin levels were significantly higher in the SR-hGH group than in the control group at 3months. There were no differences in the body weight, systolic and diastolic blood pressure (BP), bone mineral content, percentage body fat, and burn scar characteristics between groups. ConclusionOur results suggest that SR-hGH treatment during the rehabilitation of adult burn survivors positively affects physical fitness levels, muscle power, and metabolic processes, although further confirmation through research of metabolic pathways in burn survivors is required.

Oxidative stress and skeletal muscle dysfunction are present in healthy smokers

Chronic exposure to cigarette smoke seems to be related to an increase of pro-inflammatory cytokines, oxidative stress and changes in muscular and physical performances of healthy smokers. However, these parameters have not yet been evaluated simultaneously in previous studies. The participants of this study were healthy males divided into two groups: smokers (n=20) and non-smokers (n=20). Inflammation was evaluated by measuring plasma levels of the cytokines IL-10, IL-6 e TNF-α, and of the soluble receptors sTNFR1 and sTNFR2. Oxidative stress was evaluated by determination of thiobarbituric acid reactive substances (TBARS) plasma levels, total antioxidant capacity of plasma and erythrocytes activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase. Muscular performance was evaluated by measuring the peak torque of knee flexors and extensors, and by determining the total work of the knee extensors. Physical performance was assessed by measuring the peak oxygen uptake (VO2 peak), the maximum heart rate (HRmax) and the walking distance in the shuttle walking test. Smokers showed an increase in the levels of the sTNFR1 and TBARS and a decrease in the total antioxidant capacity of plasma, in the catalase activity and in the total work (P<0.05). IL-6, IL-10, sTNFR2, SOD, peak torque, VO2 peak, HRmax and walking distance were similar between groups. Smokers presented increased oxidative stress and skeletal muscle dysfunction, demonstrating that the changes in molecular and muscular parameters occur simultaneously in healthy smokers.

Comparative study on isokinetic capacity of knee and ankle joints by functional injury.

[Purpose] To collect basic data for exercise programs designed to enhance functional knee and ankle joint stability based on isokinetic measurement and muscle strength evaluations in normal and impaired functional states. [Subjects and Methods] Twenty-four subjects were randomly assigned to the athlete group and the control group (n = 12 each). Data were collected of isokinetic knee extensor and flexor strength at 60°/sec, 180°/sec, and 240°/sec and ankle plantar and dorsiflexor strength at 30°/sec and 120°/sec. [Results] Significant intergroup differences were observed in peak torque of the right extensors at 60°/sec, 180°/sec, and 240°/sec and the right flexors at 240°/sec. Significant differences were observed in peak torque/body weight in the right extensors at 60°/sec, 180°/sec, and 240°/sec and in the right flexors at 180°/sec and 240°/sec. Significant peak torque differences were noted in the left ankle joint dorsiflexor at 30°/sec and 120°/sec, right plantar flexor at 120°/sec, left plantar flexor at 30°/sec, left dorsiflexor at 30°/sec and 120°/sec, and right dorsiflexor at 120°/sec. [Conclusion] Isokinetic evaluation stimulates muscle contraction at motion-dependent speeds and may contribute to the development of intervention programs to improve knee and ankle joint function and correct lower-extremity instability.

Isokinetic profile of subjects with the ruptured anterior cruciated ligament.

All changes in the knee that appear after anterior cruciate ligament (ACL) lesion lead to difficulties in walking, running, jumping especially during sudden changes of the line of movement. This significantly impairs quality of life of these subjects and leads to decrease in physical activity. Knee injuries make 5% of all most severe acute sport injuries. The aim of the study was to determine strength of the thigh muscles in persons with unilateral rupture of the ACL and to evaluate potential bilateral differences between healthy and injured leg. This study involved 114 male athletes of different sport specialities with the clinical diagnosis of ACL rupture. Each subject had unilateral ACL rupture and the other leg was actually the control for this research. An isokinetic device was used to evaluate the muscle strength of thigh muscles. Testing was performed for two testing speeds, 60º/s and 180º/s. Data analysis showed a statistically significant difference (p < 0.01) between the ACL and the healthy leg in the following parameters: peak torque for thigh extensors (Ptrq_E), angle to peak torque during extension (Ang_E), power of extension (Pow_E) and work during extension (Work_E). Analysing hamstrings to quadriceps (H/Q) ratio we found the unilateral disbalance of thigh muscle strength in ACL leg. A high level of validity makes isokinetic dynamometry the method for evaluation of thigh muscles strength and leaves this field of research open for new studies in order to improve both diagnostic and rehabilitation of patients with the insufficient ACL.

Acute Effects of Kinesio Taping on Knee Extensor Peak Torque and Stretch Reflex in Healthy Adults.

Kinesio Tex tape (KT) is used to prevent and treat sports-related injuries and to enhance muscle performance. It has been proposed that the direction of taping may either facilitate or inhibit the muscle by having different effects on cutaneous receptors that modulate excitability of the motor neurons. This study had 2 goals. First, we wished to determine if KT application affects muscle performance and if the method of application facilitates or inhibits muscle performance. This was assessed by measuring isokinetic knee extension peak torque in the knee extensor. Second, we assessed neurological effects of taping on the excitability of the motor neurons by measuring the reflex latency and action potential by electromyography (EMG) in the patellar reflex. The study was a single-blind, placebo-controlled crossover trial with 28 healthy volunteers with no history of knee injuries. Participants received facilitative KT treatment, inhibitory KT treatment, or Hypafix taping of the knee extensor. There were significant differences in the peak torque between 3 treatments (F(2,54) = 4.873, P < 0.01). Post hoc analysis revealed that facilitative KT treatment resulted in higher knee extensor peak torque performance than inhibitory KT treatment (P = 0.036, effect size 0.26). There were, however, no significant differences in the reflex latency (F(2,54) = 2.84, P = 0.067) nor in the EMG values (F(2,54) = 0.18, P = 0.837) in the patellar reflex between the 3 taping applications. The findings suggest that the direction of KT application over the muscle has specific effects on muscle performance. Given the magnitude of effect is small, interpretation of clinical significance should be considered with caution. The underlying mechanism warrants further investigation.

Effects of ankle joint mobilization with movement and weight-bearing exercise on knee strength, ankle range of motion, and gait velocity in patients with stroke: a pilot study.

[Purpose] The purpose of this study was to investigate the effects of ankle joint mobilization with movement on knee strength, ankle range of motion, and gait velocity, compared with weight-bearing exercise in stroke patients. [Subjects and Methods] Thirty subjects with chronic stroke were divided into three groups: MWM (n = 12), WBE (n = 8), and control (n = 10). All groups attended physical therapy sessions 3 times a week for 5 weeks. Subjects in the MWM group performed mobilization with movement exercises, whilst participants in the WBE group performed weight-bearing exercises. Knee peak torque, ankle range of motion, and spatiotemporal gait parameters were evaluated before and after the interventions. [Results] Knee extensor peak torque increased significantly in both MWM and WBE groups. However, only the MWM group showed significant improvement in passive and active ankle range of motion and gait velocity, among the three groups. [Conclusion] Ankle joint mobilization with movement intervention is more effective than simple weight-bearing intervention in improving gait speed in stroke patients with limited ankle motion.

Oryantiring Sporcularının Performans Ölçümleri: Geç Ergenler, Genç Erişkinler ve Yetişkinler

Objective: To analyze performance measures of the orienteers including, static and dynamic balance, agility, speed, flexibility, knee muscle strength, aerobic and anaerobic performance and to set the differences between adolescents, young adults and adults. Material and Methods: 31 male orienteering players included in the study. First group consisted of adolescents aged between 15-19 years (n=9), second group consisted of young adults aged between 20-24 years (n=11), third group consisted of adults aged between 25-30 years (n=11). Isokinetic knee muscle strength testing, sit and reach test, star excursion balance test, 20 meter sprint test , flamingo balance test, vertical jump and reach test, T-drill test and 20 meters shuttle run test were performed in two sessions. Results: MaxVO2 levels and flexor and extensor peak torques of nondominant legs at 120°/sec were different among groups, respectively (p=0.006, p=0.01, p=0.003). The differences in MaxVO2 levels were between adolescents and young adults (p=0.007) and between adolescents and adults (p=0.002). The differences flexor and extensor peak torques of nondominant legs at 120 °/sec were between adolescents and young adults respectively (p=0.02, p=0.02). Extensor peak torque of nondominant legs at 120°/sec was different between young adults and adults (p=0.001). Other performance measures were not different among groups (p>0.05). CCoonncclluussiioonn:: It was seen that late adolescents have similar performance capacity when compared with young adults and adults except aerobic power and knee muscle strength of nondominant legs at 120°/sec. Aerobic capacity and knee muscle strength of nondominant legs should be increased by training.

Coativação e pico de torque dos músculos extensores e flexores do joelho em indivíduos hemiparéticos crônicos nas posições sentada e supina

Disorders in co-activation and decreased muscle strength are often described in hemiparetic subjects. Changes in muscle length resulting from postural change may result in different responses of co-activation and strength of these individuals. The objective of this study was to evaluate the influence of sitting and supine positions in Co-activation Index (CI) and peak torque (PT) of chronic hemiparetic subjects after stroke. The participants were twenty individuals with mean age of 54±12.14 years; mean body mass index of 26.93±3.34 kg/m²; average stroke time of 55.85±49.4 months; Mini-Mental State Examination score between 27-30; and Fugl-Meyer of lower limb between 15-30. The electromyographic record was obtained while the volunteers performed five isokinetic contractions (60o/s) of knee extension and flexion in the sitting and supine positions. The semitendinosus muscle of paretic limb exhibited lower CI in the supine position compared to sitting: 0.36±0.33; 0.44±0.33 (p=0.048). There was no difference in CI of the rectus femoris between positions: 0.28±0.25 sitting and 0.23±0.21 supine. The PT of extensor and flexor muscles of the paretic limb did not vary between positions (PT extensor: sitting = 56.48±37.62 Nm, supine = 52.29±32.37 Nm; PT flexor: sitting = 12±11.1 Nm, supine = 10.95±6.4 Nm). The supine position showed lower CI in the semitendinosus muscle of paretic limb. The change of position did not influence the CI of rectus femoris muscle neither the PT of both muscle groups of the paretic limb. Thus, the supine position appears to be indicated during movement and strength training of these muscles in chronic hemiparetic patients after stroke.

Knee Muscles Isokinetic Evaluation after a Six-Month Regular Combined Swim and Dry-Land Strength Training Period in Adolescent Competitive Swimmers.

Previous studies demonstrated significant increases in the shoulder internal rotators’ peak torque values and unilateral muscular imbalances of the shoulder rotators after a competitive swim period. However, there are no similar data concerning the knee muscles. The purpose of the current study was to examine the effects of a six-month training period on knee flexor and extensor peak torque values, examine a possible bilateral strength deficit and evaluate the unilateral strength balance in competitive swimmers. Eleven male adolescent swimmers (age: 14.82 ± 0.45 years) were tested for concentric knee extension and flexion peak torque (60°/s) with an isokinetic dynamometer, before and after a regular combined swim and dry-land strength training period. A trend towards greater improvements in the knee extensor compared to flexor muscles peak torque was observed. Furthermore, the bilateral strength deficit remained almost unchanged, whereas unilateral strength imbalance was increased for both limbs. However, all results were non-significant (p > 0.05). According to the data presented, a six-month regular combined swim and dry-land strength training period caused non-significant alterations for all the parameters evaluated during isokinetic testing. This study highlights the fact that competitive adolescent swimmers demonstrated unilateral knee strength imbalances throughout a long period of their yearly training macrocycle.

Isokinetic Assessment and Musculoskeletal Complaints in Paralympic Athletes: A Longitudinal Study.

The aim of this study was to assess and monitor the peak torque of the knee extensor and flexor muscles in flexion and extension and the reports of musculoskeletal complaints in members of the main Brazilian Paralympic athletics team through 1 yr. Fourteen healthy athletes from both sexes were assessed three times in 1 yr. The volunteers were assessed for the presence of musculoskeletal complaints and muscle strength at three time points: (1) at the onset of the preparatory phase on December 2009, (2) at a follow-up assessment on June 2010, and (3) before actual competition on December 2010. The athletes' self-reported musculoskeletal complaints were assessed in structured interviews, and the muscle strength was assessed by means of isokinetic dynamometry. The knee flexor and extensor muscle strength exhibited significant increase in both the right and left lower limbs at the second and third assessments compared with the first one (P < 0.05). Muscle imbalance was associated with knee and thigh complaints at all three assessments (P < 0.05). The knee flexor and extensor muscle strength exhibited a gradual increase in both lower limbs during the course of the three assessments. In parallel, muscle imbalance was associated with the occurrence of knee and thigh complaints.

Efeitos da caminhada em declive na aptidão aeróbia e neuromuscular em adultos jovens

Eccentric exercise training using low intensity-high volume approach has been performed to improve maximal muscle strength and power. The aim of this study was to compare the effects of short-term downhill walking and level walking training on lower limb strength and maximal oxygen uptake of active individuals. Eighteen young adults were divided into level walking group (n = 9) or downhill walking training group (n = 9). Both groups performed a four-week training program. The level walking group performed seven level walking sessions per week, while the downhill walking group walked downhill (-16%) in the same weekly frequency. One week before and one week after the training protocol, maximal oxygen uptake, muscle-bone cross-sectional area and isometric peak torque of knee extensors and plantar flexors were assessed for both groups. A significant group vs. time interaction was found only for cross sectional area of plantar flexors (PF), showing increases for the downhill walking group (112.6 ± 28.9 cm2 vs. 115.9 ± 29 cm2) but not for the level walking group (94.9 ± 23.3 cm2vs. 94.6 ± 228 cm2). Maximal oxygen uptake remained unaltered after training for both groups and IPT was increased after training for both groups. It was concluded that short-term downhill walking training does not seem to be efficient in promoting improvements in cardiorrespiratory fitness of young adults. However, it seems to promote gains in some variables related to neuromuscular fitness.

Isokinetic adaptations of knee extensors and flexors after aerobic walk training in old sedentary women

We examined the effects of active walk training 3 days per week, for 24 weeks on isokinetic peak torque (PT) and mean power (MP) of the knee extensors and flexors of osteopenic sedentary old women. The population was composed by 121 women (65.5 ± 4.2 years) with 5.3 (± 1.7) to the Physical Activity Scale for the Elderly (PASE) and 86% of the theoretical distance of the 6-minute walk test (6MWT). The women were eligible to participate if they had no medical contraindication and were not diagnosed with major motor and neurocognitive dysfunctions. The isokinetic performance of the knee extensors and flexors in both limbs was measured on Biodex System 3 ® in concentric/concentric condition on 80° range of motion. The experimental protocol consisted in 5 maximal effort performed at 60°/sec, 60 second of rest interval and 5 maximal effort at 180°/sec. After 5 minutes of rest, identical paradigm was performed on contro-lateral side. Experimental group performed aerobic walk training: (1) between 60 and 80% of maximal heart rate; (2) with a distance between 1500 to 4500 meters at the end of the training; (3) with a total time effort between 25 to 45 minutes at the end of the training. Our results showed significant increase of PT of hamstring in dominant side at 180°/sec ( p < 0.01). We observed significant differences in the experimental group for the hamstring at 60°/sec for the dominant side ( p < 0.02) and the no-dominant side ( p < 0.01). For MP, no interaction was observed between groups and time. For the hamstring, we observed significant increase in the experimental group at 60°/sec on the no-dominant side ( p < 0.05). Our results indicate a moderate effects of the aerobic walk training performed during 6 months on the peak torque and the mean power of isokinetic knee extensors and flexors in old sedentary women.

Unilateral eccentric resistance training: A direct comparison between isokinetic and dynamic constant external resistance modalities

Aim of the study was to compare the effects of unilateral eccentric-only training using constant velocity vs. constant external load. Forty-seven participants were randomized in isokinetic (IK), dynamic constant external resistance (DCER) unilateral eccentric training or control groups. Knee extension 1RM and isometric, eccentric and concentric knee extensors peak torque, as well as changes in vastus lateralis fascicle pennation angle, fascicle length, muscle thickness, and quadriceps fat-free mass were measured. Both IK and DCER training consisted in 5 × 8 eccentric-only repetitions, 2d/w, for 6 weeks. IK and DCER training sessions were matched for total volume. After training, both IK and DCER similarly increased 1RM (respectively, +4.4 kg, CI95% 1.8–7.0 and +5.5 kg, CI95% 3.3–7.9), isometric (respectively, +34.5 N/m, CI95% 23.0–45.9 and +15.8, CI95% 5.4–26.2) and concentric peak torque (respectively, +17.0 N/m, CI95% 6.6 to +27.4 and 12.2 CI95% 2.8–21.7). IK increased eccentric peak torque significantly more than DCER (respectively, +84.2 N/m, CI95% 66.3–102.1 and +38.2 N/m, CI95% 21.9–54.4). Both IK and DCER similarly increased fascicle length (respectively, +14.7 mm, CI95% 5.4–24.0 and +14.4 mm, CI95% 5.4–23.3) and muscle thickness (respectively, +3.3 mm, CI95% 1.5–5.1, and +4.1 mm, CI95% 2.5–5.7). Matching the training volume resulted in similar adaptations comparing eccentric-only IK or DCER resistance training. Both in rehabilitation and in training practice, the use of easily available gym devices can be a good substitute for expensive and often unavailable IK devices.

The Effects of Resistance Training on Lower and Upper Body Strength Gains in Young Women

It has been reported that hypertrophy gains is greater in upper body compared to lower body, however, there is no consensus that muscular strength gains are greater in upper body than in lower body. Therefore, the aim of the present study was to compare the strength gains between knee extensors and elbow flexors in response to similar resistance training regimens. Fifty five untrained young women (age: 21.6 ± 2.9 years, weight: 58.3 ± 9.0 kg and height: 163.6 ± 7.5 cm (Mean±SD)) participated in the study as volunteers. Resistance training was performed twice a week for 10 weeks. All subjects performed three sets of 8-12 maximum repetitions for leg press, knee flexion, lat pull down and bench press exercises. Unilateral knee extensors and elbow flexors peak torque (PT) were measured before and after the training period by performing two sets of four repetitions at 60°s -1 , on an isokinetic dynamometer. There were significant increases in PT for both elbow flexors (11.74% [8.0, 17.7], p 0.05). However, there was no correlation between gains in knee extensors and elbow flexors PT. The analysis of knee extensors PT lead to the formation of two clusters groups: 1) High responders (n=10): 28.29 ± 8.74% and 2) Low-responders (n=37): 7.94 ± 5.95%. Both groups had significant increases in knee extensors PT, however, increases in the high responders were higher than in low responders (p< 0.05).These results suggest that upper- and lower body muscles present similar strength gains after similar resistance training regimens in untrained young women, although individual muscle response may vary in upper and lower body muscles. Keywords: Knee extensors, Elbow flexors, Peak torque

Single-Leg Squat Performance is Impaired 1 to 2 Years After Hip Arthroscopy

ObjectiveTo evaluate single-leg squat performance 1-2 years after arthroscopy for intra-articular hip pathology compared with control subjects and the nonsurgical limb, and to investigate whether single-leg squat performance on the operated limb was associated with hip muscle strength. DesignCross-sectional study. SettingPrivate physiotherapy clinic and university laboratory. ParticipantsThirty-four participants (17 women, 36.7 ± 12.6 years) 1-2 years after hip arthroscopy and 34 gender-matched control subjects (17 women, 33.1 ± 11.9 years). MethodsParticipants performed single-leg squats using a standardized testing procedure. Squat performance was captured using video. Video footage was uploaded and reformatted for analyses. Hip muscle strength was measured with handheld dynamometry using reliable methods. Outcome MeasuresFrontal plane pelvic obliquity, hip adduction, and knee valgus were measured. Repeated measures analysis of variance evaluated between-group differences, with limb as a within-subjects factor (surgical versus nonsurgical) and gender as a between-subjects factor (P < .05). ResultsThe hip arthroscopy group demonstrated significantly greater apparent hip adduction (mean difference 2.7°, 95% confidence interval [CI] 0.7°-4.8°) and apparent knee valgus (4.0°, 95% CI 1.0°-7.1°) at peak squat depth compared with control subjects. The operated limb also demonstrated significantly greater pelvic obliquity during single-leg stance compared with the nonsurgical limb (1.2°, 95% CI 0.1°-2.3°). Women had significantly greater apparent hip adduction (standing 1.6°, 95% CI 0.5°-2.6°; peak squat depth 2.4°, 95% CI 0.3°-4.4°) and apparent knee valgus (standing 3.3°, 95% CI 1.8°-4.7°; peak squat depth 3.1°, 95% CI 0°-6.1°). Significant positive correlations were found between frontal plane angles and hip flexor and extensor peak torque (P > .05). ConclusionOne to 2 years after hip arthroscopy, deficits in single-leg squat performance exist that have the potential to increase hip joint impingement and perpetuate postoperative symptoms. Rehabilitation after hip arthroscopy should target retraining in functional single-leg positions.

Acute effects of two different stretching techniques on isokinetic strength and power

ObjectivesTo examine and compare the acute effects of short duration static and dynamic lower-limb stretching routines on the knee flexor and extensor peak torque and mean power during maximal concentric and eccentric muscle actions. MethodForty-nine active adults completed the following intervention protocols on separate days: non-stretching, static stretching and dynamic stretching. After the stretching or control intervention, concentric and eccentric isokinetic peak torque and mean power of the leg extensors and flexors were measured in prone position. Measures were compared via a fully-within-groups factorial ANOVA. ResultsNeither static nor dynamic stretching has influence on isokinetic peak torque and mean power when they were compared with the control condition. Paired comparison also showed that the isokinetic strength and power results reported by dynamic stretching session were slightly higher than those found during the static stretching session. ConclusionsShort pre-exercise static and dynamic lower-limb stretching routines did not elicit stretching-induce reductions or improvements in knee flexor and knee extensor isokinetic concentric and eccentric strength. In addition, the findings of the current study support the claim that dynamic stretching may be preferable to static stretching as part of a warm-up designed to prepare for physical activity.

Core stability training on lower limb balance strength

This study aimed to assess the effects of core stability training on lower limbs’ muscular asymmetries and imbalances in team sport. Twenty footballers were divided into two groups, either core stability or control group. Before each daily practice, core stability group (n = 10) performed a core stability training programme, while control group (n = 10) did a standard warm-up. The effects of the core stability training programme were assessed by performing isokinetic tests and single-leg countermovement jumps. Significant improvement was found for knee extensors peak torque at 3.14 rad · s−1 (14%; P < 0.05), knee flexors peak torque at 1.05 and 3.14 rad · s−1 (19% and 22% with P < 0.01 and P < 0.01, respectively) and peak torque flexors/extensors ratios at 1.05 and 3.14 rad · s−1 (7.7% and 8.5% with P < 0.05 and P < 0.05, respectively) only in the core stability group. The jump tests showed a significant reduction in the strength asymmetries in core stability group (−71.4%; P = 0.02) while a concurrent increase was seen in the control group (33.3%; P < 0.05). This study provides practical evidence in combining core exercises for optimal lower limbs strength balance development in young soccer players.

Sedentary time is not independently related to postural stability or leg strength in women 50-67 years old.

Most research on sedentary behaviour has focused on cardiometabolic outcomes and markers of metabolic dysfunction, while neuromuscular outcomes have received less attention. The objective of the present study was to determine whether sedentary time is negatively associated with laboratory-based measures of lower body muscular strength and postural stability in middle-aged women. Forty-nine women (56.6 ± 4.1 years) participated in the study. Participants wore an ActiGraph GT3X accelerometer for 7 days to quantify sedentary time and physical activity. Following a familiarization session, assessments of lower body muscular strength and postural stability were performed. Peak torque of knee extensors and flexors was assessed using an isokinetic dynamometer. Postural stability was assessed using computerized dynamic posturography and a composite equilibrium score (CES) was calculated. Participants spent 9.4 ± 1.3 h per day (65% of wear time) sedentary and 28.2 ± 17.3 min per day (3.3% of wear time) in moderate to vigorous physical activity (MVPA). Postural stability and relative peak torque of the knee flexors were significantly associated with time spent sedentary (r = -0.35, p = 0.01 and r = -0.31, p = 0.03, respectively). Multiple linear regression analyses showed that after adjusting for MVPA, sedentary time was not significantly related to either CES or peak torque of the knee extensors or flexors. In contrast to our hypothesis, postural stability and leg strength were not independently related to sedentary time. While sedentary behaviour may be an important risk factor for cardiometabolic disease, the present results suggest MVPA may be more important to neuromuscular outcomes.