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PubMed1995

Peak torque of quadriceps and hamstring muscles in basketball and soccer players of different divisions.

Basketball and soccer are two games with different training and playing procedures. The purpose of this study was to examine the maximal voluntary peak torques of the quadriceps and hamstring muscles, and the torque ratio between these muscle groups in basketball players (n = 61) and soccer players (n = 51) participating in teams of different divisions. Isokinetic peak torques were measured using the Cybex II isokinetic dynamometer at 60 and 180 degrees.s-1. Basketball players of the national team produced higher peak torque values of quadriceps muscles than the other basketball players of different divisions (p < 0.05 to p < 0.001). Hamstring peak torques of the national basketball team were significantly higher the only velocities measured compared with the players from division II and IV (p < 0.05). Peak torque values of quadriceps muscles relative to body weight were significantly higher in the national basketball team compared with basketball players from division I. No significant differences were found in peak torque values of quadriceps and hamstring muscles within the different basketball and soccer divisions. Peak torque expressed in absolute terms was significantly higher in basketball players than in soccer players (p < 0.05 to p < 0.001). However, these differences were not significant when the strength of quadriceps and hamstring muscles was expressed relative to body weight. The H/Q ratio did not differ either ditto among the different divisions of basketball and soccer players. Based on the data obtained in this study, we concluded that the subjects' body weight have a decisive effect on the production of peak torque values of quadriceps and hamstring muscles in basketball and soccer players. Furthermore that the playing in different divisions, as well as participating in different sports, i.e. basketball or soccer, have surprisingly small effects on the peak isokinetic torque production of the quadriceps and hamstring muscles.

Adult↗
PubMed2000

Ankle spasticity and strength in children with spastic diplegic cerebral palsy.

Ankle spasticity and strength in 27 children with spastic diplegic cerebral palsy (CP) (mean age 9 years, range 3 to 18 years) and a group of 12 children without CP (comparison group) (mean age 9 years, range 5 to 18 years) were observed. To measure spasticity, a KinCom dynamometer dorsiflexed the passive ankle at five different speeds and recorded the resistive plantarflexion torques. Work values for the torque-angle data were calculated at each speed. Using this data, linear regression was used to measure spasticity. To measure strength, the dynamometer rotated the ankle from maximum dorsiflexion to maximum plantarflexion at a speed of 10 degrees/s while the child performed a maximum plantarflexion concentric contraction. The movement was reversed to record maximum dorsiflexion. Maximum torques and work by the plantarflexors and dorsiflexors were calculated. The group with CP had significantly more spasticity in the plantarflexors and significantly less strength in the plantarflexors and dorsiflexors than the group without CP. Results provide objective information quantifying ankle spasticity and strength in children with CP.

Adolescent↗
PubMed2001

Submaximal exercise capacity and maximal power output in polio subjects.

OBJECTIVES: To compare the submaximal exercise capacity of polio subjects with postpoliomyelitis syndrome (PPS) and without (non-PPS) with that of healthy control subjects, to investigate the relationship of this capacity with maximal short-term power and quadriceps strength, and to evaluate movement economy. DESIGN: Cross-sectional survey. SETTING: University hospital. PARTICIPANTS: Forty-three polio subjects (25 PPS, 18 non-PPS) and 12 control subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Power output, oxygen uptake, and heart rate were measured in an incremental submaximal cycle ergometry test. Maximal short-term power was measured in 5-second all-out efforts. Knee extensor strength was measured on a chair dynamometer. RESULTS: The mean submaximal power +/- standard deviation at 80% of heart rate reserve of 83.8 +/- 29.9 watts in the polio subjects was significantly less than the mean submaximal power of 142.1 +/- 30.4 watts in the control group. However, expressed as a percentage of the maximal short-term power, submaximal power did not differ between the groups. Strength and maximal short-term power correlated significantly (p < .005) with submaximal power (r = .64 and .76, respectively). The oxygen uptake was higher than theoretically expected for the given submaximal power output in polio subjects, and appeared to increase with increasing asymmetry in strength and power between legs. No differences were found between PPS and non-PPS subjects. CONCLUSION: The submaximal work capacity of polio subjects was severely reduced, mainly in association with the reduced muscle capacity. And, because of a reduced movement economy, their energy cost was elevated. Although muscle loads in activities such as walking and climbing stairs differ from cycling, they also may require elevated relative levels of effort, predisposing subjects to premature fatigue in sustained activity.

Adult↗
PubMed2005

The effect of resistance training combined with timed ingestion of protein on muscle fiber size and muscle strength.

Acute muscle protein metabolism is modulated not only by resistance exercise but also by amino acids. However, less is known about the long-term hypertrophic effect of protein supplementation in combination with resistance training. The present study was designed to compare the effect of 14 weeks of resistance training combined with timed ingestion of isoenergetic protein vs carbohydrate supplementation on muscle fiber hypertrophy and mechanical muscle performance. Supplementation was administered before and immediately after each training bout and, in addition, in the morning on nontraining days. Muscle biopsy specimens were obtained from the vastus lateralis muscle and analyzed for muscle fiber cross-sectional area. Squat jump and countermovement jump were performed on a force platform to determine vertical jump height. Peak torque during slow (30 degrees s-1) and fast (240 degrees s-1) concentric and eccentric contractions of the knee extensor muscle was measured in an isokinetic dynamometer. After 14 weeks of resistance training, the protein group showed hypertrophy of type I (18% +/- 5%; P < .01) and type II (26% +/- 5%; P < .01) muscle fibers, whereas no change above baseline occurred in the carbohydrate group. Squat jump height increased only in the protein group, whereas countermovement jump height and peak torque during slow isokinetic muscle contraction increased similarly in both groups. In conclusion, a minor advantage of protein supplementation over carbohydrate supplementation during resistance training on mechanical muscle function was found. However, the present results may have relevance for individuals who are particularly interested in gaining muscle size.

Adult↗
PubMed2004

Isometric strength and dynamic back extensor endurance are unrelated in children ages 6-10 years: a pilot study.

This study assessed the correlation between back extensor isometric force and dynamic endurance in 69 children 6-10 years of age. Subjects were positioned prone with legs and hips supported and restrained on two folded 6-in. mats. 42 subjects (20 girls; 22 boys) performed three 5-sec. isometric back extension efforts against a calibrated dynamometer and peak force values were averaged. An additional 27 subjects (9 girls; 18 boys) also performed a dynamic (0 degrees --> 45 degrees flexion-->0 degrees) back extension test at a frequency of 20 per minute, and the number of repetitions was recorded. Both tests were repeated at a 1-wk. interval. Pearson correlations for the endurance, the isometric force test, and test-retest, and between the functional concentric endurance vs isometric force were .55, .79 (both p<.01), and .03, respectively. These tests have moderate to high reliability but they examine different aspects of back muscle fitness. They should not be used interchangeably to assess back extensor muscle fitness. Further investigation must determine whether different dynamic test frequencies and mat heights yield different results.

Back↗
PubMed2002

The relationships among peak torque, mean power output, mechanomyography, and electromyography in men and women during maximal, eccentric isokinetic muscle actions.

The purpose of the present investigation was to examine the velocity-related patterns of peak torque (PT), mean power output (MP), mechanomyographic (MMG) amplitude, and electromyographic (EMG) amplitude of the vastus lateralis (VL) muscle in men and women during maximal, eccentric isokinetic muscle actions of the leg extensors. Eight women [mean (SD)] [aged 23 (3) years] and seven men [aged 23 (2) years] volunteered for this investigation. Their PT was measured on a calibrated dynamometer at randomly ordered velocities of 30, 90, and 150 degrees x s(-1). A piezoelectric MMG recording sensor was placed between bipolar surface EMG electrodes (Ag-AgCl) over the VL muscle. Their MP was determined using the dynamometer software. The results indicated no sex-related differences (P > 0.05) for the patterns of PT, MP, MMG amplitude, or EMG amplitude across velocity. The normalized values for MP and MMG amplitude increased (P<0.05) from 30 to 150 degrees x s(-1) (30 degrees x s(-1) <90 degrees x s(-1) < 150 degrees x s(-1)), while PT and EMG amplitudes remained unchanged across velocity. The results indicated close associations between the velocity-related patterns of MP and MMG amplitudes as well as PT and EMG amplitudes. Thus, MMG amplitude reflected the velocity-related changes in muscle power output, but not torque production, while EMG amplitude reflected torque production, but not muscle power output. During maximal, eccentric isokinetic muscle actions, EMG and MMG signals provided unique information regarding the electrical and mechanical aspects of muscle strength and power.

Adult↗
PubMed1994

Sources of variation in back and leg dynamometry.

Three investigations were carried out to examine the concurrent validity and the reliability of a portable dynamometer (Takei Kiki Kogyo) for the measurement of back and leg strength. First, leg extension strength of 19 subjects was measured using the Takei dynamometer and compared to the isometric knee extension strength of the dominant (right) leg measured using a computer-controlled dynamometer (Lido Active, Davis, CA). The back extension strength of 18 subjects was also compared between the two dynamometers. Second, back and leg strengths of 36 subjects, aged 19-30 years, were measured twice using the Takei dynamometer. Six days separated the test and retest. Third, back and leg strengths of four subjects, aged 21-30 years, were measured at six different times of the solar day. Significant relations (p < 0.001) were obtained between the Takei and Lido dynamometers for leg strength (r = 0.90) and back strength (r = 0.79). Significant test-retest correlations (p < 0.001) were found for leg strength (r = 0.80) and back strength (r = 0.91). Group mean (+/- SD) leg strength values of test (1450.4 +/- 428.6 N) and retest (1432.8 +/- 449.1 N) did not differ ((p > 0.05). A small (4.5%) but significant difference was found between the test (1057.2 +/- 309.9 N) and retest (1106.2 +/- 334.4 N) mean values for back strength (p < 0.05). A time of day effect was evident for back and leg strength (p < 0.05); on average the peak times occurred at 16:53 h and 18:20 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2006

[Strength, postural and gait changes following rehabilitation in multiple sclerosis: a preliminary study].

OBJECTIVE: To evaluate the impact of rehabilitation on balance, gait and strength in inpatients with multiple sclerosis (MS). METHODS: Twenty-one in patients with MS benefited from a program of rehabilitation with evaluation before and after rehabilitation. Balance was assessed by stabilometry, walking speed with use of a locometer device and maximal peak torque of knee extensor and flexor with use of an isokinetic dynamometer at 60 degrees /s speed. The functional independence measure (FIM) was also applied before and after rehabilitation. RESULTS: After rehabilitation, patients showed significant improvement in balance with opened and closed eyes, velocity gait, strength of the lower quadriceps and the higher hamstrings and FIM values. Absolute values of gait speed and strength parameters were related as were improvement in velocity speed and the higher hamstrings. CONCLUSION: The results are encouraging and confirm the interest and tolerance of a program of rehabilitation among patients with MS.

Adult↗
PubMed2002

Efficacy of two forms of electrical stimulation in increasing quadriceps strength: a randomized controlled trial.

OBJECTIVE: To investigate whether electrical stimulation is effective in improving quadriceps strength in healthy subjects and to compare interferential and low-frequency current in terms of the effects on quadriceps strength and perceived discomfort. DESIGN: Randomized, controlled study. SETTING: Physical Medicine and Rehabilitation Department in a university hospital. SUBJECTS: Thirty medical faculty students, divided into three groups, participated in the study. INTERVENTIONS: Group A received electrical stimulation with bipolar interferential current while group B received electrical stimulation with low-frequency current (symmetrical biphasic). Group C served as the control group. Electrical stimulation was given for 15 minutes, five days a week for three weeks, at a maximally tolerated intensity with the knee fully extended in the sitting position. MAIN OUTCOME MEASURES: Before and after the study, quadriceps strength was measured with a Cybex dynamometer isokinetically at the angular velocities of 60 degrees/s and 120 degrees/s. The perceived discomfort experienced with each type of electrical stimulation was quantified by the use of a visual analogue scale (VAS). RESULTS: Statistically significant increase in isokinetic strength was observed after training in group A and group B. Increase in strength did not differ between the stimulation groups. No significant change in strength occurred in group C. Perceived discomfort by the stimulation groups was not significantly different. CONCLUSION: Both interferential and low-frequency currents can be used in strength training with the parameters used in this study.

Adult↗
PubMed1997

Isokinetic torque, average power, and flexion/extension ratios in nondisabled adults and adults with mental retardation.

For successful placement of individuals with mental retardation into community environments, a minimal amount of functional strength is required to promote self-independence. Since muscular strength and power are commonly deficient in these groups, the purpose of this study was to compare isokinetic elbow flexion and extension peak torque (Nm), average power (W), and corresponding flexion/extension ratios of adults males with Down syndrome, with mental retardation without Down syndrome, and sedentary adult males without mental retardation. Subjects with Down syndrome (N = 9), mental retardation without Down syndrome (N = 13), and without mental retardation (N = 13) were tested for elbow flexion and extension peak torque and average power at 60 and 90 degrees/sec on a Cybex 340 isokinetic dynamometer. Results indicated: 1) subjects without mental retardation displayed significantly greater ( p < 0.01) peak torque and average power elbow flexion and extension than subjects with Down syndrome and subjects with mental retardation without Down syndrome at speeds of 60 and 90 degrees/sec, and 2) there were no significant differences between groups in peak torque and average power elbow flexion/extension ratios at both angular velocities. The results of the data analysis support the premise that adults with mental retardation are in need of exercise programs to improve muscular strength.

Adult↗
PubMed2002

Grip strength after carpal tunnel release: role of the transverse caxpal ligament.

Weakness after carpal tunnel release is common. Potential factors are transverse carpal ligament (TCL) division, incision or pillar pain, swelling, and flexor tenosynovitis. In the study reported here, we examined the effect of TCL division on reactive grip-strength changes. A minimally invasive technique was used with local anesthesia and sedation for TCL release in 41 hands. Total grip strength and individual-digit grip strength were measured using a computerized dynamometer. These measurements were taken preoperatively; immediately after TCL division; and 1, 3, and 5 weeks postoperatively. There was no significant difference between total grip strength measured preoperatively and strength measured immediately after TCL division, but the difference between these values and strength measured 1 week postoperatively was significant. Preoperatively, index fingers contributed 25.3% of total grip strength; long fingers, 31.3%; ring fingers, 27.0%; and small fingers, 16.4%. These contributions were approximately the same after TCL division.

Adult↗
PubMed1999

Eccentric/concentric ratios at selected velocities for the invertor and evertor muscles of the chronically unstable ankle.

OBJECTIVE: The use of muscle balancing by the clinician to determine return to activity or discharge of a patient is not a well understood measure. Because of the lack of information on the poorly understood concept of eccentric/concentric (E/C) ratios at the ankle, the purpose was to determine the E/C ratios for the invertor and evertor muscles at various velocities in healthy and chronically unstable ankles. METHODS: Ten subjects with healthy ankles and 14 with chronically unstable ankles performed five maximal effort reciprocal eccentric/contraction contractions on an isokinetic dynamometer at four velocities (60, 120, 180, and 240 degrees/s) and for each physiological movement of inversion and eversion. Data were analysed using a two way mixed model analysis of variance with repeated measures, with Tukey's test used for post hoc analysis. RESULTS: Although the chronically unstable ankle was significantly weaker (p < 0.05) eccentrically and concentrically for inversion and eversion, the main effect of the E/C ratios for the ankle was not significant for either joint motion. The main effect of velocity was significant (p < 0.05) for each joint motion, but no significant interaction effects were observed. As velocity increased, the E/C ratio increased, except at 180 and 240 degrees/s for either ankle group. CONCLUSIONS: Chronic ankle instability and muscle weakness co-exist. Adequate E/C ratios in the chronically unstable ankle may exist in the absence of normal strength values.

Adult↗
PubMed1996

Sport-seasonal changes in body composition, growth, power and strength of adolescent wrestlers.

Changes in body composition, somatic growth, power and strength of high school wrestlers (W, n = 8, 15.9 +/- 0.3 yrs) and controls (C, n = 6, 16.1 +/- 0.2 yrs) were studied early, mid-, late-, and 3.5-months post-season. Elbow flexion peak power (FPP), peak torque (FPT), extension peak power (EPP), and peak torque (EPT) were measured on an isokinetic dynamometer. C demonstrated normal rates of somatic growth and gains in strength and power. However, for W, significant (p < 0.05) decreases were found in: weight (WT, 61.6 +/- 2.8 to 59.2 +/- 2.8 kg), relative fat (%BF) (7.8 +/- 0.7 to 6.1 +/- 0.7 %), FPT (33.3 +/- 2.3 to 29.9 +/- 2.7 Nm), FPP (125.8 +/- 0.3 to 107.8 +/- 8.4 W), EPT (37.5 +/- 2.5 to 36.2 +/- 3.8 Nm), and EPP (132.7 +/- 8.4 to 126.7 +/- 12.3 W), between early-season and late-season and significant increases in WT (5.4 +/- 0.4 kg), fat-free mass (FFM, 4.4 +/- 0.7 kg), FPT (9.4 +/- 1.7 Nm), FPP (38.8 +/- 8.8 W), EPT (6.5 +/- 1.0 Nm), and EPP (24.4 +/- 4.7 W), between late-season and post-season. Compared to C, W had significantly (p < 0.05) smaller increases in mid-arm girth and flexed mid-arm cross-sectional muscle area (X-SECT) during the wrestling season and larger increases in shoulder girth, abdominal girth, and mid-arm girth, X-SECT, and biacromial, biilium, and anterior-posterior chest breadths during the post-season. Power and strength measures were significantly correlated with FFM, lean upper limb volume (ULV), and X-SECT (r = 0.74 to 0.93, p <0.0001). When covaried for FFM, ULV or X-SECT seasonal declines in strength and power were no longer significant while post-seasonal increases remained. In conclusion, pre- to late- season W demonstrated a lack of lean tissue accretion and reductions in strength. At post-season these variables returned to, or were above, pre-season levels. Results of analysis of covariance indicated that lean tissue changes were associated with the changes in strength and power.

Adolescent↗
PubMed1997

Abdominal-wall recovery following TRAM flap: a functional outcome study.

Abdominal-wall function was evaluated preoperatively and at intervals postoperatively in 25 consecutive patients undergoing breast reconstruction with transverse rectus abdominis myocutaneous (TRAM) flaps (single-pedicled TRAM flap, 14 patients; free TRAM flap, 9 patients; and bilateral free TRAM flaps, 2 patients). Objective measures of abdominal-wall function were performed with the B200 Isostation, a triaxial dynamometer. In addition, the patients were assessed by a physical therapist and filled out an activity questionnaire at each postoperative examination. Tests of abdominal-wall function demonstrated the greatest decrease in performance at the 6-week postoperative tests of flexion. The maximum isometric flexion torque of the pedicled TRAM flap group decreased to 58 +/- 10 percent, while the unilateral free TRAM flap group average was 87 +/- 11 percent of baseline. For the pedicled TRAM flap group this difference was significant (p = 0.004). By the 6-month evaluation, the maximum isometric flexion torque increased for both the pedicled and the free TRAM flap groups to 89 +/- 13 percent and 93 +/- 8 percent of baseline, respectively. The physical therapist evaluation of abdominal-wall strength and the activity questionnaire data showed no statistically significant differences between groups or over time. Rectus abdominis muscle harvest for pedicled TRAM flaps causes a greater insult to the abdominal wall than does free TRAM flap harvest. The ultimate clinical effect of the sacrifice of even an entire rectus abdominis muscle appears to be well tolerated by most patients. This is the first prospective outcome study of abdominal-wall function in TRAM flap patients. The clinical implications of this information will be discussed.

Abdominal Muscles↗
PubMed1994

Paradoxical variation of strength determinants with different rotation axes in trunk flexion and extension strength tests.

The aim of this study was to illustrate the influence of different levels of the fulcrum (the axis of sagittal rotation) on measured trunk flexion and extension strength and compare force and torque as a unit of measure. The isometric trunk strength was measured in 16 healthy female subjects. The dynamometer was kept at the shoulder level and the moment arm was lengthened step by step by moving the fulcrum caudally from the level of the posterior superior iliac spine to the level of the gluteal fold. The moment of force (torque) increased from 117.0 to 208.5 N.m in flexion and from 182.2 to 292.5 N.m in extension, P < 0.0001. An attempt to quantify this change was made. Paradoxically, the measured force remained at a constant level (in flexion) or slightly decreased (in extension). We concluded that torque as a measure of trunk flexion and extension strength is highly dependent on the level of the rotation axis and force appears to be less sensitive for variations with the height of the fulcrum. We would suggest that the observed increase in torque is physiological and reflects to what extent hip flexor or extensor muscles are recruited. The force, on the other hand, may better characterize a person's capability to perform functional tasks. Force and torque should strictly be distinguished from one another.

Abdomen↗
PubMed1980

The relationship of physique and body composition to strength in a group of physical education students.

Fifty-three specialist women physical education students were measured anthropometrically and from these measurements somatotype and body composition were estimated. Leg, back and grip strength dynamometers were used to measure strength indices. Arm strength was calculated from each subject's pull-ups and push-ups and lung capacity was measured using a spirometer. The somatotype ratings and percent fat measurements indicate that the P.E. students are generally more muscular and less fat for their age than non-P.E. students. There was a strong relationship between percent fat and the endomorphy rating and a moderate relationship between lean body weight and mesomorphy. The moderate relationship of the strength variables with the muscular rating, whether expressed as mesomorphy or lean body weight, suggests that the higher a subject's muscular component the greater their dynamic strength.

Adipose Tissue↗
PubMed2003

Surface electromyography assessment of back muscle intrinsic properties.

The purpose of this study was to assess (1) the reliability and (2) the sensitivity to low back pain status and gender of different EMG indices developed for the assessment of back muscle weakness, muscle fiber composition and fatigability. Healthy subjects (men and women) and chronic low back pain patients (men only) performed, in a static dynamometer, maximal and submaximal static trunk extension tasks (short and long duration) to assess weakness, fiber composition and fatigue. Surface EMG signals were recorded from four (bilateral) pairs of back muscles and three pairs of abdominal muscles. To assess reliability of the different EMG parameters, 40 male volunteers (20 controls and 20 chronic low back pain patients) were assessed on three occasions. Reliable EMG indices were achieved for both healthy and chronic low back pain subjects when specific measurement strategies were applied. The EMG parameters used to quantify weakness and fiber composition were insensitive to low back status and gender. The EMG fatigue parameters did not detect differences between genders but unexpectedly, healthy men showed higher fatigability than back pain patients. This result was attributed to the smaller absolute load that was attributed to the patients, a load that was defined relative to their maximal strength, a problematic measure with this population. An attempt was made to predict maximal back strength from anthropometric measurements but this prediction was prone to errors. The main difficulties and some potential solutions related to the assessment of back muscle intrinsic properties were discussed.

Abdominal Wall↗
PubMed2000

Circadian rhythms in human muscular efficiency: continuous physical exercise versus continuous rest. A crossover study.

This study deals with the influence of time of day on neuromuscular efficiency in competitive cyclists during continuous exercise versus continuous rest. Knee extension torque was measured in ultradistance cyclists over a 24h period (13:00 to 13:00 the next day) in the laboratory. The subjects were requested to maintain a constant speed (set at 70% of their maximal aerobic speed obtained during a preliminary test) on their own bicycles, which were equipped with cyclosimulators. Every 4h, torque developed and myoelectric activity were estimated during maximal isometric voluntary contractions of knee extensors using an isokinetic dynamometer. Mesenteric temperature was monitored by telemetry. The same measures were also recorded while the subjects were resting awake until 13:00 the next day. During activity, torque changed within the 24h period (p < .005), with an acrophase at 19:10 and an amplitude of 7.8% around the mean of 70.7%. At rest, a circadian rhythm was observed in knee extensor torque (p < .05), with an acrophase at 19:30 and an amplitude of 6% around the mean of 92.3%. Despite the standardized conditions, the results showed that isometric maximal strength varied with time of day during both a submaximal exercise and at rest without prior exercise. The sine waves representing these two rhythms were correlated significantly. Although at rest the diurnal rhythm followed muscular activity (i.e., neurophysiological factors), during exercise, this rhythm was thought to stem more from fluctuations in the contractile state of muscle.

Adult↗