Kin-Com Isokinetic Dynamometer Research Articles

Contribution of Eccentric Strength to Cutting Performance in Female Soccer Players.

Jones, PA, Dos'Santos, T, McMahon, JJ, and Graham-Smith, P. Contribution of eccentric strength to cutting performance in female soccer players. J Strength Cond Res 36(2): 525-533, 2022-The aim of this study was to examine the contribution of eccentric strength to performance of a 70-90° cutting task (CUT) (time to complete: 5 m approach, 70-90° cut, 3 m exit). Nineteen female soccer players (mean ± SD age, height, and mass; 21.7 ± 4.3 years, 1.67 ± 0.07 m, and 60.5 ± 6.1 kg) from the top 2 tiers of English women's soccer participated in the study. Each player performed 6 trials of the CUT task whereby three-dimensional motion data from 10 Qualisys proreflex cameras (240 Hz) and ground reaction forces from 2 Advanced Mechanical Technology, Inc. force platforms (1,200 Hz) were collected. Relative eccentric knee extensor (ECC-KE) and flexor peak moments (ECC-KF) were collected from both limbs at 60°·s-1 using a Kin-Com isokinetic dynamometer. Hierarchical multiple regression revealed that minimum center of mass (CM) and approach velocities (CM velocity at touchdown of penultimate foot contact) could explain 82% (79% adjusted) of the variation in CUT completion time (F(1,16) = 36.086, p < 0.0001). ECC-KE was significantly (p < 0.05) moderately associated (R ≥ 0.610) with velocities at key instances during the CUT. High (upper 50th percentile) ECC-KE individuals (n = 9) had significantly (p ≤ 0.01; d ≥ 1.34) greater velocities at key instances during the CUT. The findings suggest that individuals with higher ECC-KE produce faster CUT performance, by approaching with greater velocity and maintaining a higher velocity during penultimate and final contact, as they are better able to tolerate the larger loads associated with a faster approach.

Dorsiflexion But Not Plantarflexion Force Declines At Lower Foot Skin Temperatures

Background/Aims Muscle maximum voluntary force declines at skin temperature &lt;20°C, attributed to cold muscle, however large muscle deep fibres remain at &gt;20°C. Large muscle maximum voluntary force decline is comparable to that in small superficial muscle where muscle temperature remains close to skin temperature. Therefore, factors in addition to temperature may contribute to large muscle maximum voluntary force decline. This study compares the effects of foot and/or shank skin temperature on dorsiflexion and plantarflexion maximum voluntary force with the hypotheses that: dorsiflexion maximum voluntary force&gt;plantarflexion maximum voluntary force decline at lower skin temperature; and, plantarflexion and dorsiflexion maximum voluntary force will decline at lower shank skin temperature independent of foot skin temperature. Methods A total of 24 adults (15 females, 9 males, 29 ± 11.8 years, 170.1 ± 8.0 cm, 66.9 ± 9.3 kg [mean ± standard deviation]) gave informed consent to participate on three visits – cooling/warming of: foot only; foot and shank; and shank only. Foot and/or shank temperature was adjusted using Cryocuff™ sleeves filled with ~45°C or ~4°C water. Temperature, taken before each maximum voluntary force set, was monitored through thermocouples placed on the limb. Plantarflexion and dorsiflexion maximum voluntary force were measured with a KinCom isokinetic dynamometer, with subjects seated on a plinth with knee fully extended and neutral ankle. A general mixed model was used to evaluate the effects of skin temperature on maximum voluntary force. Fixed effects were skin temperature and condition, with subject as a random effect. The skin temperature*condition interaction was also modelled. P-values were obtained by likelihood ratio tests. Results Foot skin temperature &lt;18.5°C resulted in a 10% (χ2(1)=5.479, P=0.019) dorsiflexion maximum voluntary force decline, with a skin temperature*condition interaction (χ2(2)=11.031, P=0.004), this decline was 12% (χ2(1)=13.18, P=0.0003) in foot only and 8% (χ2(1)=4.675, P=0.031) in foot and shank. Leg skin temperature did not affect (χ2(1)=2.849, P=0.091) dorsiflexion maximum voluntary force. Plantarflexion maximum voluntary force did not change with foot skin temperature (χ2(1)=0.04, P=0.841) or leg skin temperature (χ2(1)=0.082, P=0.929). Conclusions Dorsiflexion maximum voluntary force declines at lower foot skin temperature independently of shank skin temperature, whereas plantarflexion maximum voluntary force is unaffected by skin temperature, possibly because in this protocol the shank was insufficiently cooled. Therefore factors other than direct muscle cooling must contribute to dorsiflexion maximum voluntary force decline. One theory is a rightward shift in the force-length relationship, due to stiffer tendon, could result in dorsiflexions operating in the descending limb of the force-length relationship. This warrants further investigation.

42 Eccentric isokinetic ankle strength assessment in those with ankle sprain histories and those with ankle instability

Background Strength training interventions have long been a cornerstone of ankle injury rehabilitation, with greater emphasis on the eccentric (ECC) muscle actions necessary for coordinated ankle movements. Deficits in strength between involved and uninvolved ankles typically exist following an acute ankle sprain; while these same deficits have also been implicated as a contributing factor to the development and persistence of chronic ankle instability (CAI). Objective To compare ECC isokinetic ankle strength measures between athletes with and without CAI after a history of unilateral ankle sprain. Design Cross-sectional. Setting Athletic training research laboratory. Participants A total of 135 male and female student-athletes participating in the high risk sports of football, basketball, lacrosse, soccer, field hockey, and volleyball with histories of unilateral ankle sprain. Interventions The independent variables were group classification (CAI, stable) and limb (involved, uninvolved). Subjects completed the Cumberland Ankle Instability Tool (CAIT) to define group classification with subjects scoring 25 being classified as stable. Main outcome measurements ECC isokinetic peak torque (PT) values were collected using a KinCom isokinetic dynamometer during plantar flexion (PF), dorsiflexion (DF), inversion (INV), and eversion (EV) and movements at both 30˚/s and 120˚/s. 2 × 2 ANOVAs were used to compare group (CAI, stable) and limb (involved, uninvolved) for each dependent variable. Results A significant main effect was present for ECC INV at 30˚/s (p = 0.033). The uninvolved side (26.9 ± 10.9 Nm) was stronger than the involved side (25.3 ± 9.6 Nm). A trend towards significance existed for the ECC PF, with the uninvolved side appearing to be stronger at 30˚/s (229.9 ± 74.5 Nm, p = 0.095) and 120˚/s (218.4 ± 7 9.8 Nm, p = 0.106) than the involved limb (30˚/s = 223.8 ± 82.4 Nm; 120˚/s = 207.3 ± 82.0 Nm). A similar trend was observed when examining ECC INV values at 120˚/s (p = 0.100) and ECC DF at 120 ˚ /s (p = 0.098). Interestingly, there were no significant differences between any of the group comparisons. Conclusions ECC ankle strength does not differentiate whether an athlete has CAI, but the musculature on the involved ankle appears to be weak compared to the opposite uninvolved limb. Our results add to the growing evidence suggesting that neuromuscular deficits other than strength are likely producing the chronic signs and symptoms associated with CAI.

Adaptation of local muscle blood flow and surface electromyography to repeated bouts of eccentric exercise.

The aim of this randomized controlled crossover study was to investigate the effect of a bout of unaccustomed eccentric exercise (ECC) followed by a consecutive bout of the same intensity on local muscle blood flow, amplitude, and frequency of the electromyographic (EMG) signal from the exercised tibialis anterior muscle. Sixteen healthy male participants (age, 25.7 (0.6) years; body mass index 24.8 (1) kg·m(-2) participated in this study. Two identical bouts of high-intensity ECC were performed on the tibialis anterior muscle 7 days apart. Control sessions involving no exercise were performed 4 weeks either before or after the exercise sessions. Changes in local total blood flow [ΔtHb], EMG root mean square, and median power frequency were recorded during isometric maximum voluntary contraction of ankle dorsiflexion. Measurements were performed before, immediately after, and the day after both ECCs (ECC1 and ECC2). The participants rested quietly in a chair in the control session. Eccentric exercise 1 led to a significant decrease in [ΔtHb] on the day after (p ≤ 0.05), whereas ECC2 did not. Median power frequency decreased significantly in ECC2 compared with ECC1 (p < 0.01). Root mean square was unchanged in all the instants. The present study showed that adaptation is depicted in the local muscle blood flow and the frequency contents of the EMG after an unaccustomed ECC inducing muscle soreness. These alterations provide a potential mechanism for a rapid adaptation, which decreases susceptibility of the muscle to develop further soreness in the subsequent ECC bout.

Prehabilitation versus usual care before total knee arthroplasty: A case report comparing outcomes within the same individual

This case report compared pre- and postoperative functional ability, knee strength, and pain of a female who underwent two separate total knee arthroplasty (TKA) procedures. The female patient was part of a larger research study. The first surgery on the right knee was preceded with usual care and the second surgery on the left knee was preceded by prehabilitation. Functional ability was assessed by a 6-minute walk, chair raises, and the time required to ascend and descend stairs. Knee extension and flexion isokinetic strength was assessed using the KinCom Isokinetic Dynamometer. Pain was assessed using the Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC). Functional abilities, knee strength, and pain were assessed at baseline measurements 4 weeks before surgery, 1 week before surgery, and at 1 and 3 months post surgery during each TKA procedure. Results indicate that the prehabilitation intervention had a favorable impact on improving functional ability up to 30%, increasing knee strength by 50% and decreasing pain prior to the left knee TKA. For this patient, prehabilitation increased functional ability and strength prior to surgery. Gains in strength were maintained in the nonsurgical knee after surgery. These findings indicate that prehabilitation may be effective at facilitating the rehabilitation following a TKA.

The Effects Of High Volume Aquatic Plyometric Training On Vertical Jump, Muscle Power, And Torque

Plyometric and aquatic plyometric exercises have been shown to improve athletic performance. One benefit of aquatic plyometric activities is the ability to decrease stresses on the body due to the buoyant properties of water. Buoyancy acts as a counterforce to gravity by supporting the body as it moves downward and should allow an athlete to complete higher volumes of aquatic plyometrics with the potential for increased physical outcomes. The purpose of this study was to examine the effects of high volume aquatic-based plyometrics versus traditional land or aquatic plyometric training on vertical jump (VJ), muscular peak power and torque in the dominant knee. A random sample of forty-seven healthy subjects started the training, but only thirty-nine (n = 39) completed the protocol due to non-compliancy issues and injuries that occurred outside of the training protocol (16 males: age 21.8 ± 2.3, height 181.9 ± 6.9cm, weight 80.7 ± 9.2kg; 23 females: age 22.4 ± 3.5, height 166.5 ± 5.8cm, weight 65.7 ± 10.0kg). The subjects were randomly assigned to one of four groups prior to the data collection process: aquatic group 1 (APT1, 10 subjects), aquatic group 2 (APT2, 11 subjects), land group (LPT1, 8 subjects), and control group (CON, 10 subjects). A six-week plyometric training program for the three exercise groups was conducted twice a week for approximately 30 minutes. APT1 performed a plyometric program in the aquatic setting, while LPT performed the same protocol on land. APT2 performed double the volume of the plyometric program in the aquatic setting. The control group did not participate in any plyometric training and were instructed not to alter their current exercise habits. The exercise groups participated in a plyometric training program that focused on hops and jumps of differing intensities both forward, backward, and laterally. Barriers of different heights were also included in the training program. All subjects were pre and post tested in the performance variables of vertical jump using a VerTec and concentric peak torque and power of the hamstrings and quadriceps using the dominant knee on a KinCom isokinetic dynamometer. A 2 (time) × 4 (group) ANOVA with repeated measures was used to determine if differences existed between the performance variables. At the conclusion of the six-week training program, we found no significant differences in any groups for all tested variables. However, APT2 showed the greatest increased average VJ (+ 1.3cm), overall peak power values (hamstrings, + 14.8W, quadriceps, + 1.2W), and peak torque (quadriceps, + 3.2 ft.lbs) of all training groups. Although we found no significant differences in the performance variables, APT2 improved the most in four out of five tested performance variables showing there are still benefits to aquatic plyometric training. More research is needed to determine aquatic training parameters for optical performance. Despite the fact that our training groups did not differ in their performance, there has been previous research that supports plyometric training in the aquatic environment. Health care professionals can utilize the buoyant properties of water to decrease the potential for injury and provide an excellent training environment for athletes and clients alike to increase their performance.

The effect of 4 weeks β-alanine supplementation and isokinetic training on carnosine concentrations in type I and II human skeletal muscle fibres

Seven male students were supplemented with beta-alanine (beta-ALG) for 4 weeks (6.4 g day(-1)) and seven with a matching placebo (PLG). Subjects undertook 4 weeks of isokinetic training with the right leg (T) whilst the left leg was untrained (UT), serving as a control. Each training session consisted of 10 x 10 maximal 90 degrees extension and flexion contractions at 180 degrees /s using a Kin-Com isokinetic dynamometer, with 1 min rest between bouts. Muscle biopsies were taken from the vastus lateralis immediately before and at the end of the supplementation period. Following freeze drying muscle fibres were dissected and characterised by their MHC profile, as type I, IIa, IIx, or as hybrids of these. Carnosine was measured by HPLC. There was a significant increase in carnosine in both T and UT legs of the beta-ALG (9.63 +/- 3.92 mmol kg(-1) dry muscle and 6.55 +/- 2.36 mmol kg(-1) dry muscle respectively). There was a significant increase in the carnosine content of all fibre phentotypes, with no significant difference between types. There were no significant differences in the changes in muscle or in fibres between the T and UT legs. In contrast there was no significant change in the carnosine content in either the T or UT legs with placebo. The results indicate that 4 weeks training has no effect on the muscle carnosine content. Whilst an increase was seen with beta-alanine supplementation, this was not further influenced by training. These findings suggest that beta-alanine availability is the main factor regulating muscle carnosine synthesis.

Effects of a Shoulder Injury Prevention Strength Training Program on Eccentric External Rotator Muscle Strength and Glenohumeral Joint Imbalance in Female Overhead Activity Athletes

Imbalance of the eccentrically-activated external rotator cuff muscles versus the concentrically-activated internal rotator cuff muscles is a primary risk factor for glenohumeral joint injuries in overhead activity athletes. Nonisokinetic dynamometer based strength training studies, however, have focused exclusively on resulting concentric instead of applicable eccentric strength gains of the external rotator cuff muscles. Furthermore, previous strength training studies did not result in a reduction in glenoumeral joint muscle imbalance, thereby suggesting that currently used shoulder strength training programs do not effectively reduce the risk of shoulder injury to the overhead activity athlete. Two collegiate women tennis teams, consisting of 12 women, participated in this study throughout their preseason training. One team (n = 6) participated in a 5-week, 4 times a week, external shoulder rotator muscle strength training program next to their preseason tennis training. The other team (n = 6) participated in a comparable preseason tennis training program, but did not conduct any upper body strength training. Effects of this strength training program were evaluated by comparing pre- and posttraining data of 5 maximal eccentric external immediately followed by concentric internal contractions on a Kin-Com isokinetic dynamometer (Chattecx Corp., Hixson, Tennessee). Overall, the shoulder strength training program significantly increased eccentric external total work without significant effects on concentric internal total work, concentric internal mean peak force, or eccentric external mean peak force. In conclusion, by increasing the eccentric external total exercise capacity without a subsequent increase in the concentric internal total exercise capacity, this strength training program potentially decreases shoulder rotator muscle imbalances and the risk for shoulder injuries to overhead activity athletes.

Test–retest reliability of glenohumeral internal and external rotation strength in chronic rotator cuff pathology

Objective To determine the test–retest reliability of concentric measures for internal rotation (IR) and external rotation (ER) strength in individuals with chronic rotator cuff pathology (CRCP). Design/setting Test–retest reliability study. Set at the human movement laboratory at the Centre for Health, Exercise and Sports Medicine at the University of Melbourne, Australia. Participants Ten individuals with CRCP (6 males and 4 females) were selected from a convenience sample. Concentric strength was assessed using a Kincom isokinetic dynamometer in a seated position with the glenohumeral joint placed in 45° of scapular plane abduction. Main outcome measures Peak torque and pain intensity for concentric IR and ER of the glenohumeral joint were collected. Participants performed three repetitions of glenohumeral IR and ER for both the affected and non-affected shoulder over two testing occasions, 2 days apart. Pain intensity during testing was recorded using a visual analogue scale. Results The intraclass correlation coefficient (ICC) was calculated to assess test–retest reliability. ICC's ranged from 0.90–0.96 for the affected limb and 0.75–0.86 for the non-affected limb. Conclusions Good to excellent test–retest reliability of the test protocol. Greater variation in torque production was observed in the non-affected limb. Peak torque scores were consistently reduced on the second testing occasion.

Muscular Fatigue of the Shoulder Rotator Muscles Prior To and After an Endurance Based Strength Training Program

Shoulder rotator muscle imbalance is considered a shoulder injury risk factor to the overhead athlete. Such an imbalance occurs frequently as an adaptation to overhead sports and can be counteracted by shoulder strength training of the external rotator muscles. Fatigue-induced shoulder rotator muscle imbalance, as revealed in greater fatigue of the concentrically activated external rotator muscles than of the internal rotator muscles, however, might be an additional shoulder injury risk factor to the overhead athlete. PURPOSE: To assess eccentric external and concentric internal shoulder muscular fatigue prior to and immediately after a 5 week shoulder strength training program. METHODS: Subjects were six collegiate women tennis players who participated in a 5 week, 4 times a week, preseason strength training program consisting of five exercises: External Rotation 90°, Seated Row, Scaption, Chest Press, and External Shoulder Rotation (Rubber tubing). Three sets of 15 repetitions were performed for each exercise. A Kin-Com isokinetic dynamometer was used to assess total work performed throughout 20 maximal contractions. Peak total work was denned as total work conducted during the first 5 repetitions and muscular fatigue was assessed by dividing total work conducted in the last 5 repetitions by the peak total work. RESULTS: Fatigue of the external rotator muscles was equal to fatigue of the internal rotator muscles, both prior to (External: 78.2%; Internal: 84.9%; NS) and after the shoulder strength training program (External: 62.7%; Internal: 60.5%; NS). Furthermore, relative peak concentric internal (Pre: 128 J; Post: 150 J; NS) as well as significant eccentric external total work increases (Pre: 96 J; Post: 171 J; p = 0.007) were accompanied by significantly increased levels of fatigue of the external (p = 0.037) and internal rotator muscles (p = 0.045). CONCLUSIONS: Fatigue-induced shoulder muscle strength imbalance did not occur and hence is not considered an additional shoulder injury risk factor to the overhead athlete. Finally, this study showed that in order to achieve strength increases in subsequent repetitions a greater volume and duration of the strength training program appears warranted.

Reliability of Rate of Velocity Development and Phase Measures on an Isokinetic Device

Isokinetic dynamometers have been measured for torque and force reliability in the past, but little research has been performed on rate of velocity development (RVD) measures. The purpose of this study was to determine the reliability of RVD measures on an isokinetic device at slow and fast speeds. Twenty volunteers performed 5 repetitions of concentric knee extension at 1.04 and 4.18 rad.s(-1) on a Kin-Com isokinetic dynamometer. Each subject was identically posttested 7 days later. Data were separated into 3 velocity range-of-motion (ROM) phases of RVD, load range (LR), and deceleration (DCCROM). Analyses of variance (ANOVAs) were performed to analyze the mean data between day 1 and day 2, while intraclass correlation coefficients (ICCs) were performed for reliability. Results at 1.04 rad.s(-1) demonstrated a low but significant (p < 0.05) ICC value (0.58) only for LR, while at 4.18 rad.s(-1) RVD (0.87), LR (0.83), and DCC (0.55) all exhibited significant ICC values. Percent error for high-speed testing ranged from 1.4-3.19%. No variable exhibited a significant mean difference between testing days. These results collectively point to moderate to high phase reliability for RVD measures at fast speeds of testing, while the slow speed showed very low reliability. Therefore, care should be exercised at slow speeds when comparing RVD measures from test to test.

Distinct brain activation patterns for human maximal voluntary eccentric and concentric muscle actions

Eccentric muscle contractions generate greater force at a lower level of activation and subject muscles to more severe damage than do concentric actions. A recent investigation has revealed that electroencephalogram (EEG)-derived movement-related cortical potential (MRCP) is greater and occurs earlier for controlling human eccentric than concentric submaximal muscle contractions. However, whether the central nervous system (CNS) control signals for high-intensity or maximal-effort eccentric movements differ from those for concentric actions is unknown. The purpose of this study was to determine whether the MRCP signals differ between the two types of maximal-effort contractions. Eight volunteers performed 40 maximal voluntary eccentric and 40 maximal voluntary concentric elbow flexor contractions on a Kin-Com isokinetic dynamometer. Scalp EEG signals (62 channels) were measured along with force, joint angle, and electromyographic (EMG) signals of the performing muscles. MRCP-based two-dimensional brain maps were created to illustrate spatial and temporal distributions of the MRCP signals. Although the level of elbow flexor muscle activity was lower during eccentric than concentric movements, MRCP-indicated cortical activation was greater both in amplitude and area dimension for the eccentric task. Detailed comparisons of individual electrode signals suggested that eccentric movements needed a significantly longer time for early preparation and a significantly greater magnitude of cortical activity for later movement execution. The extra preparation time and higher amplitude of activation may reflect CNS activities that account for the higher risk of injury, higher degree of movement difficulty, and unique motor unit activation pattern associated with maximal-level eccentric muscle actions.

Effects of exercise and diet on knee strength in older overweight and obese adults with knee osteoarthritis.

0638 INTRODUCTION: Previous studies have shown a strong association between obesity and knee osteoarthritis (OA). Felson and colleagues (2000) identified biomechanical factors associated with OA in weight-bearing joints, including obesity, muscular weakness, and joint laxity. Studies indicate that both obese adults (Kitagawa, 1978) and adults with knee OA (Messier et. al., 1992) are weaker than age-matched healthy controls. Short term resistance training has been shown to improve strength in older adults (Morganti, 1995), and long term resistance training in older adults with knee OA has shown significant, but modest improvements in function and strength compared to walking or a control group (Ettinger et.al.,1997). PURPOSE: Therefore, the purpose of our study was to determine the effects of exercise and dietary weight loss on muscular strength in older overweight (BMI = 28–30) and obese (BMI > 30) adults with knee OA. METHODS: A cohort of 316 older overweight and obese adults (BMI > 28) with radiographic evidence of knee OA were randomized to one of four groups: diet (D), exercise (E), diet and exercise (D&E), or healthy lifestyle control (HL) (The Arthritis Diet and Activity Promotion Trial (ADAPT)). Exercise sessions consisted of two 15-minute bouts of walking separated by 20 minutes of moderate intensity resistance training. The E and D&E groups underwent 6 months of facility-based exercise. Subsequently, participants had the option to continue in the facility-based program for an additional 12 months, transition to a home based exercise program, or combine the facility and home based programs. Dietary intervention focused on reducing fat and total calories. Weight loss goal was 5% of body weight. Bi-lateral knee strength data (concentric/eccentric flexion, concentric/eccentric extension) were collected on a randomized subset of this cohort (n = 156 at baseline) using a Kin-Com isokinetic dynamometer set at a speed of 30 deg/s. Data were collected at baseline (BAS), 6 months (FU6), and upon completion of the intervention (FU18). DATA ANALYSIS: Data were averaged over a range of 80–40 deg knee flexion (0 = extension). Knee flexion/extension strength were analyzed using the average values over this range of motion. The effects of diet and/or exercise programs on muscular strength measured at 6 and 18 months post-randomization were determined by twoway repeated measures analysis of covariance. Estimates of intervention effects were obtained at each follow-up observation. When group-by-time interactions were nonsignificant, average intervention effects over the follow-up period were estimated and tested for significance.

Effects of exercise and diet on knee strength in older overweight and obese adults with knee osteoarthritis.

0638 INTRODUCTION: Previous studies have shown a strong association between obesity and knee osteoarthritis (OA). Felson and colleagues (2000) identified biomechanical factors associated with OA in weight-bearing joints, including obesity, muscular weakness, and joint laxity. Studies indicate that both obese adults (Kitagawa, 1978) and adults with knee OA (Messier et. al., 1992) are weaker than age-matched healthy controls. Short term resistance training has been shown to improve strength in older adults (Morganti, 1995), and long term resistance training in older adults with knee OA has shown significant, but modest improvements in function and strength compared to walking or a control group (Ettinger et.al.,1997). PURPOSE: Therefore, the purpose of our study was to determine the effects of exercise and dietary weight loss on muscular strength in older overweight (BMI = 28–30) and obese (BMI > 30) adults with knee OA. METHODS: A cohort of 316 older overweight and obese adults (BMI > 28) with radiographic evidence of knee OA were randomized to one of four groups: diet (D), exercise (E), diet and exercise (D&E), or healthy lifestyle control (HL) (The Arthritis Diet and Activity Promotion Trial (ADAPT)). Exercise sessions consisted of two 15-minute bouts of walking separated by 20 minutes of moderate intensity resistance training. The E and D&E groups underwent 6 months of facility-based exercise. Subsequently, participants had the option to continue in the facility-based program for an additional 12 months, transition to a home based exercise program, or combine the facility and home based programs. Dietary intervention focused on reducing fat and total calories. Weight loss goal was 5% of body weight. Bi-lateral knee strength data (concentric/eccentric flexion, concentric/eccentric extension) were collected on a randomized subset of this cohort (n = 156 at baseline) using a Kin-Com isokinetic dynamometer set at a speed of 30 deg/s. Data were collected at baseline (BAS), 6 months (FU6), and upon completion of the intervention (FU18). DATA ANALYSIS: Data were averaged over a range of 80–40 deg knee flexion (0 = extension). Knee flexion/extension strength were analyzed using the average values over this range of motion. The effects of diet and/or exercise programs on muscular strength measured at 6 and 18 months post-randomization were determined by twoway repeated measures analysis of covariance. Estimates of intervention effects were obtained at each follow-up observation. When group-by-time interactions were nonsignificant, average intervention effects over the follow-up period were estimated and tested for significance.

Isokinetic Profile of Shoulder Internal and External Rotators of High School Aged Baseball Pitchers

The purpose of this descriptive study was to determine whether bilateral differences exist in concentric and eccentric shoulder internal and external rotation strength in high school aged baseball pitchers. Thirty-nine high school aged baseball pitchers were bilaterally tested for concentric and eccentric internal and external rotation muscle performance on a Kin-Com 500-H isokinetic dynamometer at 90 degrees .s(-1) and 180 degrees .s(-1). Paired t-tests were used to test for differences among extremities, speed, and ratio of external rotation to internal rotation (ER/IR ratios). Concentric peak torque internal rotation at 90 degrees .s(-1) was significantly greater (p < 0.05) in the dominant arm compared with the nondominant arm. Statistically significant differences (p < 0.001) were found between the nondominant and dominant in concentric 90 degrees .s(-1). The nondominant arm demonstrated significantly greater eccentric strength (p < 0.05) compared with the dominant arm in ER/IR ratios at 90 degrees .s(-1) and 180 degrees .s(-1). The nondominant arm demonstrated significantly greater eccentric strength (p < 0.05) than the dominant arm in ER/IR ratio at 180 degrees .s(-1). Data demonstrated that muscular adaptations are consistent with previous research in this area. Also, muscular adaptations occur in the shoulder in the high school aged population. These data can serve as a guideline to be used by clinicians who rehabilitate shoulders in patients in this population.

The Effects of a Neuromuscular Electrical Stimulation Home Program on Impairments and Functional Skills of a Child with Spastic Diplegic Cerebral Palsy: A Case Report

To examine the effects of neuromuscular electrical stimulation (NMES) on impairments and functional skills of a 13-year-old child with spastic diplegic cerebral palsy (CP). NMES was administered to the right quadriceps muscles every other day for six weeks. Pre- and posttesting included assessment of strength using a hand-held dynamometer, spasticity using a KinCom isokinetic dynamometer, gait spatiotemporal parameters using GAITRite, and functional motor performance with the use of the Pediatric Evaluation of Disability Inventory (PEDI). After intervention, right quadriceps strength increased from 16.3 +/- 3.06 to 41.7 +/- 4.2 Newtons. Right hamstring spasticity decreased at three tested velocities. In the untreated left lower extremity, strength remained unchanged but spasticity increased. The PEDI showed development of new skills, including the ability to climb stairs with less assistance. These findings indicate that NMES was an effective therapeutic technique to improve strength and motor function of a child with spastic diplegic CP.

EMG-angle relationship of the hamstring muscles during maximum knee flexion

The aim of the present study was to investigate the EMG–joint angle relationship during voluntary contraction with maximum effort and the differences in activity among three hamstring muscles during knee flexion. Ten healthy subjects performed maximum voluntary isometric and isokinetic knee flexion. The isometric tests were performed for 5 s at knee angles of 60 and 90°. The isokinetic test, which consisted of knee flexion from 0 to 120° in the prone position, was performed at an angular velocity of 30°/s (0.523 rad/s). The knee flexion torque was measured using a KIN-COM isokinetic dynamometer. The individual EMG activity of the hamstrings, i.e. the semitendinosus, semimembranosus, long head of the biceps femoris and short head of the biceps femoris muscles, was detected using a bipolar fine wire electrode. With isometric testing, the knee flexion torque at 60° knee flexion was greater than that at 90°. The mean peak isokinetic torque occurred from 15 to 30° knee flexion angle and then the torque decreased as the knee angle increased ( p<0.01). The EMG activity of the hamstring muscles varied with the change in knee flexion angle except for the short head of the biceps femoris muscle under isometric condition. With isometric contraction, the integrated EMGs of the semitendinosus and semimembranosus muscles at a knee flexion angle of 60° were significantly lower than that at 90°. During maximum isokinetic contraction, the integrated EMGs of the semitendinosus, semimembranosus and short head of the biceps femoris muscles increased significantly as the knee angle increased from 0 to 105° of knee flexion ( p<0.05). On the other hand, the integrated EMG of the long head of the biceps femoris muscle at a knee angle of 60° was significantly greater than that at 90° knee flexion with isometric testing ( p<0.01). During maximum isokinetic contraction, the integrated EMG was the greatest at a knee angle between 15 and 30°, and then significantly decreased as the knee angle increased from 30 to 120° ( p<0.01). These results demonstrate that the EMG activity of hamstring muscles during maximum isometric and isokinetic knee flexion varies with change in muscle length or joint angle, and that the activity of the long head of the biceps femoris muscle differs considerably from the other three heads of hamstrings.

Relationship between passive properties of the calf muscles and plantarflexion concentric isokinetic torque characteristics

The purpose of this study was to use a model of aging to examine the relationships between passive properties of the calf muscles and plantarflexion concentric isokinetic torque characteristics. Eighty-one active women 20-84 years of age were tested using a Kin-Com isokinetic dynamometer interfaced with electromyography (EMG). The passive properties were tested by stretching the muscles from relaxed plantarflexion to a maximal dorsiflexion (DF) angle at a rate of 5 degrees.s(-1) (0.087 rad.s(-1)) with minimal raw EMG activity (<0.05 mV). The maximal concentric torque was tested from maximal passive DF into plantarflexion at four randomly ordered velocities of 30, 60, 120, and 180 degrees.s(-1). Pearson correlation coefficients (Bonferroni adjusted) indicated a hierarchical order of high to moderate positive correlations between four passive properties and the peak and mean concentric torque for all test velocities. Correlation coefficients for the four passive properties ranged from 0.50 to 0.78 ( P<0.001), and the coefficients of determination ( r(2)) from higher to lower were: (1) maximal DF passive resistive torque ( r(2): 0.50-0.62), (2) length extensibility ( r(2): 0.40-0.49), (3) maximal muscle length ( r(2): 0.28-0.41), and (4) passive elastic stiffness in the last half of the full-stretch range of motion ( r(2): 0.25-0.31). The maximal DF passive resistive torque and the length extensibility accounted for 50-62% and 40-49% of the variability in the concentric torque, respectively. The results indicate that the concentrically stronger calf muscles of active women were positively correlated with passively stronger, longer, and stiffer calf muscles, which are characteristics of the calf muscles of younger women. Further studies are needed to examine whether therapeutic interventions, such as stretching and strengthening, can promote adaptations in the calf muscles of older women to attain these more youthful characteristics.

Effects of isokinetic strength training on walking in persons with stroke: A double-blind controlled pilot study

Objectives: The goal most often stated by persons with stroke is improved walking function. The purpose of this study was to determine the effects of isokinetic strength training on walking performance, muscle strength, and health-related quality of life in survivors of chronic stroke. Methods: Twenty participants (age, 61.2 ± 8.4 years) with chronic stroke were randomized into 2 groups. The experimental group undertook maximal concentric isokinetic strength training, whereas the control group received passive range of motion of the paretic lower extremity 3 times a week for 6 weeks. The Kin-Com Isokinetic Dynamometer (Chattanooga Group Inc., TN) was used for both the strengthening and passive range of motion exercises. The Mann-Whitney U test was used to compare the changes in scores (postintervention minus baseline) between the control and experimental groups for a composite lower extremity strength score, walking speed (level-walking and stair-walking) and health-related quality of life measure (36-Item Short Form Health Survey [SF-36]). Results: Both the experimental and control groups increased their strength and walking speed postintervention; however, there were no differences in the changes in walking speed between the groups. There was a trend (P =.06) toward greater strength improvement in the experimental group compared with the control group. No changes in SF-36 scores were found in either group. Conclusions: Intervention aimed at increasing strength did not result in improvements in walking. The results of this study stress the importance of controlled clinical trials in determining the effect of specific treatment approaches. Strength training in conjunction with other task-related training may be indicated. Copyright © 2001 by National Stroke Association

TEST-RETEST OF SEX HORMONE RESPONSES TO ACTIVE AND PASSIVE ISOKINETIC PROTOCOLS IN MAN

The purpose was to examine sex hormone responses to isokinetic exercise in man. Using Kin-Com isokinetic dynamometer, male students (n = 8; age = 21.5 ± 1.5 yrs; height = 175.6 ± 20.2 cm; weight = 78.6 ± 9.8 kg) performed test and retest using active and passive protocols. Active protocol consisted of maximal isokinetic concentric knee extensions and flexions tests at 120°/s with 24 hrs apart. Peak torque (PT), total work (TW), and average power (AP) while the active protocol were recorded. Passive movement was drive by dynamometer at speed of 120°/s. Hematocrit (Hct), blood glucose (G), lactate (L), seruum luteinzing hormones (LH), follicle stimulating hormone (FSH), testosterone (T) levels before and after 0, 5, 15, 30, and 60 min of the protocol were collected. Steroid honnones were determined by enzyme immunoassay (E.I.A.). Performance variables were 108.46 ± 15.67 Nm, 1858.69 ± 204.54 joules, and 119.62 ± 11.92 watts for PT, TW, and AP, respectively. Hct was found no change throughout the test. Following passive movement, no significant changes in all blood chemistries were found throughout the test and retest. Following active protocol, blood G levels were significantly elevated in 0 and 5, following the isokinetic protocol in test and 5 min after retest. Blood L were significantly elevated in 0, 5, and 15 min following the isokinetic protocol in test and retest Serum FSH levels were significantly increased in 15 and 30 min after test and 30 min after retest. Following 30 min of isokinetic test, serum LH level was significantly increased and no change after retest. Correlation of blood L, G, and serum T values between test and retest during active protocol were r = 0.67 to 0.89. In summary, 30 maximal isokinetic knee extensions and flexions stimulate blood L, G, and serum T to increase. An increased in serum T following exercise protocol is not influence by passive movement, blood volume and serum gonodatropin levels. Exercise-associated raise in blood G, L, serum FSH, LH, and T levels are repetable while perform isokinetic tests in this study Supported by NSC 89-2413-H-028-001