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At least 253 records · Page 14Linked to original sources
PubMed2003

Angle-specific impairment of elbow flexors strength after isometric exercise at long muscle length.

In this study, we examined the long-term reductions in maximal isometric force (MIF) caused by a protocol of repeated maximal isometric contractions at long muscle length. Furthermore, we wished to ascertain whether the reductions in MIF are dependent on muscle length--that is, are the reductions in MIF more pronounced when the muscle contracts at a short length. The MIF of the elbow flexors of seven young male volunteers was measured at five different elbow angles between 50 degrees and 160 degrees. On a separate day, the participants performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position; that is, with the shoulder hyperextended at 45 degrees and the elbow joint fixed at 140 degrees. Following this exercise, the MIF at the five elbow angles, range of motion, muscle soreness and plasma creatine kinase activity were measured at 24 h intervals for 4 days. On day 1, the decline in MIF was higher at the more acute elbow angles of 50 degrees (42 +/- 8%) and 70 degrees (39 +/- 8%; both P<0.01) than at 90 degrees (26 +/- 4%) and 140 degrees (16 +/- 3%; both P<0.01). No significant reduction in MIF was evident at an elbow angle of 160 degrees. Maximal isometric force at an elbow angle of 140 degrees was fully restored on day 3, whereas at an angle of 50 degrees it remained depressed for the 4 day observation period. Restoration of MIF was a function of the elbow angle, with force recovery being less at the smaller angles. The range of motion was decreased by 14 +/- 2 degrees on day 1 (P<0.01) and did not return to baseline values by day 4. Muscle soreness ratings remained significantly elevated for the 4 day period. Serum creatine kinase peaked on day 1 (522 +/- 129 IU, P<0.01) and decreased thereafter. We conclude that the disproportionate decrease in MIF at the small elbow angles and the length-specific recovery in MIF after repeated maximal isometric contractions at long muscle length may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle, therefore causing a rightward shift of the force-length relationship.

Adult↗
PubMed1994

Exercise, aging, and nutrition.

Age-associated declines in resting energy expenditure and the thermogenesis of activity result in lower energy requirements in older adults. Regular aerobic exercise programs and strength or resistive training may increase the daily energy expenditure and/or may preserve or increase the lean body mass, which decreases with increasing age. Regular strength training exercise programs may improve bone mineral density and ambulation in older adults. Nutritional assessments suggest that older adults' protein intake should be at least 1 g per kilogram of body weight, and that calcium intake should be between 1,200 and 1,500 mg/day. Regular strenuous physical activity may require subtle changes in vitamin and mineral intake to compensate for loss of minerals in sweat and for exercise-induced increases in metabolism. Older adults may have a decreased thirst response to fluid deprivation. Fluid intake must be closely monitored with exercise activity to prevent dehydration.

Adolescent↗
PubMed2001

Effects of tower climbing exercise on bone mass, strength, and turnover in growing rats.

To determine the effects of tower climbing exercise on mass, strength, and local turnover of bone, 50 Sprague-Dawley rats, 10 weeks of age, were assigned to five groups: a baseline control and two groups of sedentary and exercise rats. Rats voluntarily climbed the 200-cm tower to drink water from the bottle set at the top of it. In 4 weeks, the trabecular bone formation rate (BFR/bone surface [BS]), bone volume (BV/TV), and trabecular thickness (Tb.Th) of both the lumbar vertebra and tibia and the bone mineral density (BMD) of the tibia increased, while the osteoclast surface (Oc.S) decreased. The parameter values in the midfemur, such as the total cross-sectional area, the moment of inertia, the periosteal mineralizing surface (MS/BS), mineral apposition rate (MAR), BFR/BS, and bending load increased, while the endosteal MAR decreased. In 8 weeks, the increases in the bone mineral content (BMC), BMD of the femur and tibia, and the bending load values of the femur were significant, but the climbing exercise did not increase BMC, BMD, or the compression load of the lumbar vertebra. Although the periosteal MS/BS, MAR, and BFR/BS increased, the endosteal MS/BS, MAR, and BFR/BS decreased. These results show that climbing exercise has a beneficial effect on the femoral cortex and tibia trabecular, rather than the vertebral trabecular. In the midfemur, effects on bone formation are site specific, supporting accelerated cortical drift by mechanical stimulation.

Adipose Tissue↗
PubMed2002

Randomised controlled trial of transcutaneous electrical muscle stimulation of the lower extremities in patients with chronic obstructive pulmonary disease.

BACKGROUND: Although exercise training improves exercise tolerance in most patients with chronic obstructive pulmonary disease (COPD), some patients with severe disease may not be able to tolerate exercise training due to incapacitating breathlessness. Transcutaneous electrical muscle stimulation (TCEMS) has been shown to improve muscle strength, muscle mass, and performance in paraplegics, patients with knee ligament injury, and patients with peripheral vascular disease. We hypothesised that TCEMS of the lower extremities can improve muscle strength and exercise tolerance in patients with moderate to severe COPD. METHODS: A randomised controlled trial of TCEMS of the lower extremities was performed in 18 medically stable patients of mean (SD) age 60.0 (1.5) years with a mean forced expiratory volume in 1 second (FEV(1)) of 1.03 (0.10) l (38% predicted) and residual volume/total lung capacity (RV/TLC) of 59 (2)%. Stimulation of the lower extremities was performed three times a week, 20 minutes each session, for six continuous weeks. Quadriceps and hamstring muscle strength, exercise capacity, and peak oxygen uptake were measured at baseline and after 6 weeks of stimulation. RESULTS: TCEMS improved both the quadriceps strength (by 39.0 (20.4)% v 9.0 (8.1)%, p=0.046) and hamstring muscle strength (by 33.9 (13.0)% v 2.9 (4.7)%, p=0.038) in the treated (n=9) and sham treated (n=9) groups, respectively. The improvement in muscle strength carried over to better performance in the shuttle walk test in the treated group (36.1% v 1.6% in the treated and sham groups respectively, p=0.007, Mann-Whitney U test). There was no significant change in lung function, peak workload, or peak oxygen consumption in either group. Muscle stimulation was well tolerated by the patients with no dropouts and better than 95% compliance with the protocol. CONCLUSIONS: TCEMS of peripheral muscles can be a useful adjunct to the comprehensive pulmonary rehabilitation of patients with COPD.

Double-Blind Method↗
PubMed2001

Quadriceps concentric and eccentric exercise 2: differences in muscle strength, fatigue and EMG activity in eccentrically-exercised sore and non-sore muscles.

The purpose of this study was to determine whether the previously reported muscle weakness and increases in EMG and EMG/force ratio after eccentric exercise were related to ensuing soreness or simply to the exercise mode. Delayed-onset muscle soreness, maximal voluntary force and the surface electromyogram (EMG) of the quadriceps were studied in 10 healthy male subjects following 20 min of bench-stepping with a constant leading leg. Prior to stepping and at 0, 0.25, 0.50, 0.75, 1, 3, 24 and 48 h afterwards the subjects performed a 30 s isometric maximal voluntary contraction (MVC) of the extensors of each leg during which the isometric force and the root mean square voltage of the surface EMG (rms EMG) were recorded. Muscle soreness was recorded prior to and at 0, 0.75, 3, 24 and 48 h after the stepping task by means of a force probe. No soreness was experienced in the concentrically exercised muscles, but in the eccentrically exercised muscles 5 subjects were not sore and 5 experienced soreness after 24 h, increasing to 48 h. There were no significant differences between sore and non-sore muscles in muscle weakness, fatigue during 30 s, the EMG amplitudes or the EMG/force ratios during peak force and the 30 s MVC (p >0.05). Muscle weakness following eccentric exercise was related to the exercise mode and was independent of subsequent soreness. Both weakness and soreness may be related to muscle damage, but involve different mechanisms.

Adult↗
PubMed2004

Effect of exercise on the bone strength, bone mineral density, and metal content in rat femurs.

We have investigated the effect of exercise on the bone strength, bone mineral density (BMD), and metal content in rat femurs. Five Wister rats acting as an exercised group (E group) were exercised at intervals on a treadmill every day for four weeks. Another five rats were fed in a cage, acting as a control group (C group), without any exercise. After four weeks, the bend strength, Young's modulus, BMD value, and metal content of the femurs were measured using a three-point bend test, Dual-Energy X-ray Absorptiometry (DEXA), and chemical analysis. The bend strength of the E group was 101+/-5 MPa, and that of the C group was 86+/-7 MPa. The Young's modulus was 1.16+/-0.03 GPa for the E group, and 0.98+/-0.06 GPa for the C group. The BMD values were 0.179+/-0.002 g/cm(2) for the E group, and 0.166+/-0.002 g/cm(2) for the C group. The Ca concentration was 230600 +/- 1500 microg/g for the E group, and 223000 +/- 2700 microg/g for the C group. The Zn concentration was 160 +/- 7 microg/g for the E group, and 188 +/- 8 microg/g for the C group.

Adaptation, Physiological↗
PubMed2002

Bone mineral density in adolescent female athletes: relationship to exercise type and muscle strength.

PURPOSE: This study investigated the influence of different exercise types and differences in anatomical distribution of mechanical loading patterns on bone mineral density (BMD) in elite female cyclists, runners, swimmers, triathletes, and controls (N = 15 per group). Associations between leg strength and BMD were also examined. METHODS: Areal BMD (g x cm(-2)) was assessed by duel-energy x-ray absorptiometry (DXA) (total body (TB), lumbar spine (LS), femoral neck (FN), legs, and arms). Right knee flexion and extension strength was measured using a Cybex Norm isokinetic dynamometer at 60 degrees x s(-1). RESULTS: Runners had significantly higher unadjusted TB, LS, FN, and leg BMD than controls (P < 0.05); higher TB, FN, and leg BMD than swimmers (P < 0.05); and greater leg BMD than cyclists (P < 0.05). Absolute knee extension strength was significantly (P < 0.01) correlated (0.33 < or = r < or = 0.44) with TB, FN, LS, and leg BMD for all groups combined. Weaker but still significant correlations (0.28 < or = r < or = 0.33) existed for normalized (per leg lean tissue mass) knee extension strength and all BMD sites, except FN BMD. There were no significant correlations between absolute or normalized knee flexion strength and any of the BMD variables. Absolute knee extension strength was entered as the second independent predictor for LS and leg BMD in stepwise multiple linear regression analysis (MLRA), accounting for increments of 4% and 12%, respectively, in total explained variation. CONCLUSION: We conclude that running, a weight bearing exercise, is associated with larger site-specific BMD than swimming or cycling, that the generalized anatomical distribution of loads in triathlon appears not to significantly enhance total body BMD status, and that knee extension strength is only a weak correlate and independent predictor of BMD in adolescent females.

Adolescent↗
PubMed2000

Strength and physiological response to exercise in patients with chronic fatigue syndrome.

OBJECTIVE: To measure strength, aerobic exercise capacity and efficiency, and functional incapacity in patients with chronic fatigue syndrome (CFS) who do not have a current psychiatric disorder. METHODS: Sixty six patients with CFS without a current psychiatric disorder, 30 healthy but sedentary controls, and 15 patients with a current major depressive disorder were recruited into the study. Exercise capacity and efficiency were assessed by monitoring peak and submaximal oxygen uptake, heart rate, blood lactate, duration of exercise, and perceived exertion during a treadmill walking test. Strength was measured using twitch interpolated voluntary isometric quadriceps contractions. Symptomatic measures included physical and mental fatigue, mood, sleep, somatic amplification, and functional incapacity. RESULTS: Compared with sedentary controls, patients with CFS were physically weaker, had a significantly reduced exercise capacity, and perceived greater effort during exercise, but were equally unfit. Compared with depressed controls, patients with CFS had significantly higher submaximal oxygen uptakes during exercise, were weaker, and perceived greater physical fatigue and incapacity. Multiple regression models suggested that exercise incapacity in CFS was related to quadriceps muscle weakness, increased cardiovascular response to exercise, and body mass index. The best model of the increased exercise capacity found after graded exercise therapy consisted of a reduction in submaximal heart rate response to exercise. CONCLUSIONS: Patients with CFS were weaker than sedentary and depressed controls and as unfit as sedentary controls. Low exercise capacity in patients with CFS was related to quadriceps muscle weakness, low physical fitness, and a high body mass ratio. Improved physical fitness after treatment was associated with increased exercise capacity. These data imply that physical deconditioning helps to maintain physical disability in CFS and that a treatment designed to reverse deconditioning helps to improve physical function.

Adult↗
PubMed1984

Strength recovery patterns following exercise with an imposed myotatic stretch.

An investigation was conducted to determine the effects of isometric exercise with an imposed myotatic stretch on the resultant pattern of strength recovery in trained and untrained subjects. Thirty 5-second maximal isometric contractions were administered to 12 trained and 12 untrained men with an intertrial interval of 10 seconds. On one day a 1-second stretch was delivered during each 5-second trial, while on another day, only isometric exercise was performed. Results showed that the pattern of strength recovery over the 10-minute recovery period was similar for both groups and both exercise conditions. However, during the first minute of the recovery period, the imposed stretch exercise resulted in a much faster rate of strength recovery than isometric exercise. It is concluded that the recovery of maximal isometric strength can be altered with the type of muscle contraction involved in the exercise task.

Adult↗
PubMed1987

Reproducibility of pressor response to handgrip: influence of time intervals, strength and duration of exercise.

1. The reproducibility of pressor response to handgrip performed at different time intervals and with different combinations of the product duration x strength of the exercise was evaluated in 14 normotensive subjects recording blood pressure with a noninvasive automatic device. 2. Subjects underwent five consecutive tests (30% of maximal voluntary contraction x 90 s) at 30 min, and 24 h intervals and repeated the test after 12 months. Furthermore, they underwent at 24 h intervals a randomized sequence of handgrip tests whose product strength x duration was combined in order to achieve either a constant or an increasing level of exercise. 3. Blood pressure response to exercise performed at 30 min intervals was much less reproducible than that induced by handgrip performed at time intervals greater than or equal to 24 h. 4. Increasing gradually the product strength x duration of the handgrip test there was a proportional blood pressure increase, whereas when the product was maintained constant diastolic blood pressure increase was also constant and reproducible within each subject. 5. This study shows that it is possible to obtain reproducible diastolic blood pressure responses to handgrip test measuring blood pressure with a non-invasive automatic device when the tests are performed at a time interval of at least 24 h. The choice of the strength and of the duration of the exercise is very important for the reproducibility of the test.

Adult↗
PubMed1979

Increase of muscle strength from isometric quadriceps exercises at different knee angles.

Isometric quadriceps exercises were performed at two different knee angles, 15 and 60 degrees respectively. The maximal torque was measured in both positions before and after training in 10 healthy females. Both legs were exercised, one at each position. The purpose was to develop practical recommendations for choice of training position. The strength increase was mainly specific according to the angle at which the knee was exercised. It was suggested that isometric exercise would preferably be performed at different knee angles to secure an optimal total strength increase. Isometric exercises improved dynamic strength at a low velocity but not at a high velocity.

Adult↗
PubMed1995

Muscle strength, symptom intensity, and exercise capacity in patients with cardiorespiratory disorders.

The contribution of muscle strength to symptom intensity and work capacity was examined in normal individuals and patients with cardiorespiratory disorders. Respiratory muscle strengths (maximal inspiratory and expiratory pressures) and peripheral muscle strengths (leg extension, leg flexion, seated bench press, and seated row) were measured in 4,617 subjects referred for clinical exercise testing. Subjects then rated the intensity of leg effort, discomfort with breathing (dyspnea), and chest pain (Borg scale) during an incremental exercise task (100 kpm/min each minute) to capacity on a cycle ergometer. Subjects were classified into groups on the basis of pulmonary function, drug therapy for cardiac disorders, and the presence of chest pain during exercise with electrocardiographic changes indicative of myocardial ischemia. Respiratory and peripheral muscle strengths, normalized for differences in age, sex, and height, were significantly reduced in patients with cardiorespiratory disorders compared with normal individuals. Muscle strength was a significant contributor to symptom intensity and work capacity in both health and disease; a two-fold increase in muscle strength was associated with a 25 to 30% decrease in the intensity of both leg effort and dyspnea and a 1.4- to 1.6-fold increase in work capacity. These results emphasize the need for an integrative approach in the assessment and therapeutic management of exercise intolerance, which considers the contribution of muscle weakness to excessive symptoms and reduced work capacity, in addition to the contribution of ventilatory, gas exchange, and circulatory impairments.

Angina Pectoris↗
PubMed2006

Long stick exercise to improve muscular strength and flexibility in sedentary individuals.

The objective of this study was to investigate the effects of long stick exercise training on the strength and flexibility of sedentary individuals. An observational prospective study was conducted at the Prince of Songkla University. Eighty-five subjects who did not engage in any regular physical activity for at least three months before the study. A long stick exercise program was taught by a master for 45 minutes, at least three times weekly, for three months. Handgrip strength, back-leg strength, and flexibility were measured at the beginning of the program as a baseline, and at one, two, and three months of training. The subjects had increased back-leg strength and flexibility. Median back-leg strength increased from the baseline by 0.07 kg/weight, 0.19 kg/weight, and 0.21 kg/weight, at one, two, and three months, respectively (p< 0.05). Median flexibility (sit-and-reach test) improved from the baseline by 4.34 cm, 4.71 cm, and 5.56 cm, at one, two, and three months, respectively (p = 0.001). There were no statistically significant changes in handgrip strength.

Adult↗
PubMed2004

The effect of 15 weeks of exercise on balance, leg strength, and reduction in falls in 40 women aged 65 to 89 years.

OBJECTIVE: Risk of falling increases as people age, and decreased leg strength and poor balance have been implicated as contributors. Our aims were to:1) assess the efficacy of a fall-prevention exercise program on balance and leg strength in women aged 65 to 89 years and 2) conduct a 1-year follow-up to determine the effect of exercise on fall rates. METHODS: Forty women were classified by falling history and fear of falling and assigned to exercise and control groups using stratified randomization. We used the Berg Balance Scale, Get-up and Go, Functional Reach, and Wall-Sit Tests to evaluate changes in balance and leg strength before and after a supervised 15-week exercise program (31-hr sessions/week). We conducted 1-year follow-up telephone interviews and compared the number of falls reported by exercise and control groups.The study used a 2 x 2 (exercise/control by pretest/post-test) factorial design with the testing times being a repeated factor, so we used analysis of variance (ANOVA) to evaluate differences between the 2 groups across testing times. Power analysis computed a priori with STPLAN software (Version 4.2) showed that a sample size of 40 was necessary to determine statistical differences in balance and leg strength. RESULTS: Exercise subjects showed significant improvement on 5 of 14 items (5.2%, p < or = 05 to 34.4%, p < or = .01) in the Berg Balance Scale and on the total score (6.8%, p < or = .05). Leg strength increased significantly (p < or = .05) on post-test as measured by the Wall-Sit Test. Control subjects reported 6 falls and exercise subjects no falls during the follow-up year, but this difference was not significant using Fischer's exact test (p=.106). CONCLUSION: The exercise program resulted in increased balance and leg strength, but did not result in a significant difference in falls during the follow-up period. Further research with a larger and possibly older sample is needed to more adequately investigate this question. Health care providers who work with older women should provide exercise programs in which balance and leg strength are emphasized.

Accidental Falls↗