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PubMed1990

Muscle strength as a predictor of bone mineral density in young women.

It is widely accepted that physical activity is beneficial to bone. However, the specific relationships of muscle strength to bone mineral density (BMD) are poorly understood. We examined strength and BMD in 59 women aged 18-31 years who ranged in exercise patterns from sedentary to active. Mineral density of the right proximal femur (hip) and spine (L2-4) was evaluated by dual-energy x-ray absorptiometry. BMD at the midradius was measured by single-photon absorptiometry. Dynamic strength (one repetition maximum) was measured for the following muscle groups: back, elbow flexors (biceps), leg extensors (quadriceps), and the hip flexors, extensors, adductors, and abductors. Isometric grip strength was assessed by dynamometry. Mineral density at the hip correlated independently with muscle strength and body weight, but not with age. Specifically, femoral neck BMD was significantly correlated with back strength and weight, whereas trochanter and overall hip mineral density were significantly related to biceps, back, and hip adductor strength. Hip mineral density was not related to strength of the quadriceps groups or to that of the hip flexors, extensors, or abductors. In addition, muscle strength was an independent predictor of lumbar spine and midradius mineral density. In stepwise multiple regression analysis, biceps strength proved the most robust predictor of hip BMD and grip strength best predicted bone density at the lumbar spine and radius. We conclude that muscle strength is an independent predictor of bone mineral density, accounting for 15-20% of the total variance in bone density of young women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1984

Muscle strength and cross-sectional area in man: a comparison of strength-trained and untrained subjects.

This study has examined muscle strength and cross-sectional area in a group of 35 healthy untrained male subjects and 8 subjects who had been engaged in a strenuous weight-training programme. The maximum voluntary knee extension force which could be produced by the untrained subjects was 742 +/- 100 N (mean +/- SD). The trained subjects could produce a significantly (p less than 0.001) greater force (992 +/- 162 N). Cross-sectional area of the knee-extensor muscle group was 81.6 +/- 11.8 cm2 in the untrained subjects and 104.1 +/- 12.3 cm2 in the trained subjects (p less than 0.001). In the untrained subjects, a significant correlation existed between strength and muscle cross-sectional area (r = 0.56, p less than 0.001). In the same group of subjects, there was a significant inverse relationship between muscle cross-sectional area and the ratio of strength to cross-sectional area (r = 0.55, p less than 0.001). The mean ratio of strength to cross-sectional area was 9.20 +/- 1.29 for the untrained group whereas for the trained group this ratio was 9.53 +/- 1.01. It is suggested that the inverse relationship between strength per unit cross-sectional area and cross-sectional area results in part from an increased angle of pennation in the larger muscles.

Adult↗

PubMed2000

Bone mineral density and muscle strength in female ice hockey players.

The purpose of this study was to investigate bone mineral density (BMD) at different sites in female ice hockey players as well as to study the relationship between BMD, muscle strength, and body composition parameters. The study group consisted of 14 female ice hockey players (age 22.2 +/- 4.3 years) which was compared with 14 inactive females (age 21.5 +/- 3.8 years). The two groups were matched for age and weight. Areal bone mineral density was measured in total body, head, lumbar spine, femoral neck, Ward's triangle and the trochanter, using dual energy X-ray absorptiometry. Body composition parameters were derived from the total body scan. Isokinetic concentric peak torque of the left quadriceps and hamstrings muscles was measured using an isokinetic dynamometer. Compared to the inactive group, the ice hockey players had significantly higher BMD of all of the bone sites measured, except for the head, (total body 6.9%, head -2.6%, lumbar spine 8.9%, femoral neck 17.6%, Ward's triangle 20.4%, and trochanter 21.7%). The hockey players also had significantly higher peak torque in the quadriceps and hamstrings muscles. In the ice hockey group, a significant positive correlation was found between BMD of the femoral neck and hamstrings peak torque at 225 degreesisecond (r = 0.67, P < 0.01). In the inactive group, significant positive correlations were found between BMD and peak torque in the hamstrings muscles (90 degrees/second: r = 0.6-0.8, P<0.05 (total body, trochanter) and P<0.01 (spine, neck), 225 degrees/second: r = 0.5-0.8, P<0.05 (total body, Ward's triangle, trochanter) and P< 0,01 (spine, neck)). In the inactive group significant positive correlations was also found between lean body mass and BMD of the trochanter (r = 0.58, P < 0.05). In young females it appears that training and playing ice hockey might influence BMD and muscle strength in a positive direction. The correlation between BMD and muscle strength seems to weaken with increased exercise level.

Absorptiometry, Photon↗

PubMed1998

The effect of six months treatment with a 100 mg daily dose of dehydroepiandrosterone (DHEA) on circulating sex steroids, body composition and muscle strength in age-advanced men and women.

OBJECTIVE: The biological role of the adrenal sex steroid precursors--DHEA and DHEA sulphate (DS) and their decline with ageing remains undefined. We observed previously that administration of a 50 daily dose of DHEA for 3 months to age-advanced men and women resulted in an elevation (10%) of serum levels of insulin-like growth factor-I (IGF-I) accompanied by improvement of self-reported physical and psychological well-being. These findings led us to assess the effect of a larger dose (100 mg) of DHEA for a longer duration (6 months) on circulating sex steroids, body composition (DEXA) and muscle strength (MedX). SUBJECTS AND DESIGN: Healthy non-obese age-advanced (50-65 yrs of age) men (n = 9) and women (n = 10) were randomized into a double-blind placebo-controlled cross-over trial. Sixteen subjects completed the one-year study of six months of placebo and six months of 100 mg oral DHEA daily. MEASUREMENTS: Fasting early morning blood samples were obtained. Serum DHEA, DS, sex steroids, IGF-I, IGFBP-1, IGFBP-3, growth hormone binding protein (GHBP) levels and lipid profiles as well as body composition (by DEXA) and muscle strength (by MedX testing) were measured at baseline and after each treatment. RESULTS: Basal serum levels of DHEA, DS, androsternedione (A), testosterone (T) and dihydrotestosterone (DHT) were at or below the lower range of young adult levels. In both sexes, a 100 mg daily dose of DHEA restored serum DHEA levels to those of young adults and serum DS to levels at or slightly above the young adult range. Serum cortisol levels were unaltered, consequently the DS/cortisol ratio was increased to pubertal (10:1) levels. In women, but not in men, serum A, T and DHT were increased to levels above gender-specific young adult ranges. Basal SHBG levels were in the normal range for men and elevated in women, of whom 7 of 8 were on oestrogen replacement therapy. While on DHEA, serum SHBG levels declined with a greater (P < 0.02) response in women (-40 +/- 8%; P = 0.002) than in men (-5 +/- 4%; P = 0.02). Relative to baseline, DHEA administration resulted in an elevation of serum IGF-I levels in men (16 +/- 6%, P = 0.04) and in women (31 +/- 12%, P = 0.02). Serum levels of IGFBP-1 and IGFBP-3 were unaltered but GHBP levels declined in women (28 +/- 6%; P = 0.02) not in men. In men, but not in women, fat body mass decreased 1.0 +/- 0.4 kg (6.1 +/- 2.6%, P = 0.02) and knee muscle strength 15.0 +/- 3.3% (P = 0.02) as well as lumbar back strength 13.9 +/- 5.4% (P = 0.01) increased. In women, but not in men, an increase in total body mass of 1.4 +/- 0.4 kg (2.1 +/- 0.7%; P = 0.02) was noted. Neither gender had changes in basal metabolic rate, bone mineral density, urinary pyridinoline cross-links, fasting insulin, glucose, cortisol levels or lipid profiles. No significant adverse effects were observed. CONCLUSIONS: A daily oral 100 mg dose of DHEA for 6 months resulted in elevation of circulating DHEA and DS concentrations and the DS/cortisol ratio. Biotransformation to potent androgens near and slightly above the range of their younger counterparts occurred in women with no detectable change in men. Given this hormonal milieu, an increase in serum IGF-I levels was observed in both genders but dimorphic responses were evident in fat body mass and muscle strength in favour of men. These differences in response to DHEA administration may reflect a gender specific response to DHEA and/or the presence of confounding factor(s) in women such as oestrogen replacement therapy.

Aged↗

PubMed2000

A retrospective comparison of abdominal muscle strength following breast reconstruction with a free TRAM or DIEP flap.

Abdominal weakness is a known potential complication of breast reconstruction with a pedicled or free TRAM flap. It has been presumed that the DIEP flap, which involves no muscle resection, does not compromise abdominal muscle strength but little objective research exists to substantiate this. The aims of this retrospective study were to compare abdominal muscle strength following free TRAM flap and DIEP flap, to compare both groups with a control group and to establish the effect of both procedures on functional activities. Fifty women (23 with a DIEP flap, 27 with a free TRAM flap) plus 32 non-operated controls underwent assessment of their abdominal and back extensor muscle strength on a KIN COM isokinetic dynamometer. Two questionnaires were used to establish the impact on function. The TRAM flap group had significant weakness of the abdominal and back extensor muscles compared with the DIEP flap group and the control group. The trend was for the DIEP flap group to have weaker abdominal muscles than the control group. There was a higher level of abdominal pain and a greater number of reported functional difficulties in the TRAM flap group than in the DIEP flap group. This study demonstrates that whilst the DIEP flap can reduce the strength deficit caused by the free TRAM flap, abdominal weakness can still result from the DIEP flap. A randomised controlled trial is currently underway to investigate the effect of preoperative abdominal exercises in preventing/minimising postoperative abdominal muscle weakness in this group.

Abdominal Muscles↗

PubMed2001

Race and sex effects on the association between muscle strength, soft tissue, and bone mineral density in healthy elders: the Health, Aging, and Body Composition Study.

Two factors generally reported to influence bone density are body composition and muscle strength. However, it is unclear if these relationships are consistent across race and sex, especially in older persons. If differences do exist by race and/or sex, then strategies to maintain bone mass or minimize bone loss in older adults may need to be modified accordingly. Therefore, we examined the independent effects of bone mineral-free lean mass (LM), fat mass (FM), and muscle strength on regional and whole body bone mineral density (BMD) in a cohort of 2,619 well-functioning older adults participating in the Health, Aging, and Body Composition (Health ABC) Study with complete measures. Participants included 738 white women, 599 black women, 827 white men, and 455 black men aged 70-79 years. BMD (g/cm2) of the femoral neck, whole body, upper and lower limb, and whole body and upper limb bone mineral-free LM and FM was assessed by dual-energy X-ray absorptiometry (DXA). Handgrip strength and knee extensor torque were determined by dynamometry. In analyses stratified by race and sex and adjusted for a number of confounders, LM was a significant (p < 0.001) determinant of BMD, except in white women for the lower limb and whole body. In women, FM also was an independent contributor to BMD at the femoral neck, and both FM and muscle strength contributed to limb BMD. The following were the respective beta-weights (regression coefficients for standardized data, Std beta) and percent difference in BMD per unit (7.5 kg) LM: femoral neck, 0.202-0.386 and 4.7-5.9%; lower limb, 0.209-0.357 and 2.9-3.5%; whole body, 0.239-0.484 and 3.0-4.7%; and upper limb (unit = 0.5 kg), 0.231-0.407 and 3.1-3.4%. Adjusting for bone size (bone mineral apparent density [BMAD]) or body size BMD/height) diminished the importance of LM, and the contributory effect of FM became more pronounced. These results indicate that LM and FM were associated with bone mineral depending on the bone site and bone index used. Where differences did occur, they were primarily by sex not race. To preserve BMD, maintaining or increasing LM in the elderly would appear to be an appropriate strategy, regardless of race or sex.

Absorptiometry, Photon↗

PubMed1988

Improvement of muscle strength in familial hypokalaemic periodic paralysis with acetazolamide.

A double blind cross-over study of eight patients with familial hypokalaemic periodic paralysis was made to assess the influence of acetazolamide on muscle strength. All patients had a reduced interictal muscle fibre conduction velocity. Five patients had no attacks at the time of the study. One patient withdrew from the study because of an adverse reaction. The muscle strength of 11 muscle groups was measured with a hand-held dynamometer. The sum of force improved significantly in the seven patients (mean increase: 17%, p less than 0.05; 95% confidence interval: 7.2-26.8%). Endurance tests showed an improvement in the performance of 30 full kneebends. Surface EMG measurement showed no change in the muscle fibre conduction velocity or power spectra during treatment. The integrated EMG showed a (non significant) mean increase of 21%.

Acetazolamide↗

PubMedDate not supplied

Muscle strength as a predictor of loss of functional status in hospitalized patients.

OBJECTIVE: The incidence of protein-calorie malnutrition in hospitalized adult patients can reach 30% to 50% and adversely affect clinical outcome. We evaluated the efficacy of muscle strength to predict functional derangement and detect early changes in nutrition status in hospitalized patients. METHODS: Patients hospitalized at medical and surgical wards from two different hospitals in Santiago, Chile, were studied during their hospital stay. Subjective Global Assessment of nutrition status and laboratory parameters were measured on admission. Anthropometric measures, handgrip dynamometry, and maximal inspiratory and expiratory pressures were measured on admission and discharge. The Karnofsky index was used to assess functional status. Twice weekly, caloric balance was calculated with indirect calorimetry and assessment of dietary intake. RESULTS: From the initial selection of patients (n = 70), 50 patients (26 men and 24 women) completed the study. Median hospital stay was 10 d. Subjective Global Assessment was associated with anthropometric data, handgrip dynamometry, and serum levels of total proteins. Patients in whom functional status declined during hospital stay, on admission had lower left handgrip strength, a worse Subjective Global Assessment classification, were older, and had lower fat mass. No association between caloric balance during hospital stay and changes in muscle strength was observed. CONCLUSIONS: Subjective Global Assessment, handgrip strength, and fat mass were good predictors for the decline in functional status during hospital stay. No association between caloric balance and changes in muscle strength was observed.

Adult↗

PubMed1984

Inspiratory muscle strength and body composition in patients receiving total parenteral nutrition therapy.

We examined the relationship between inspiratory muscle strength and body composition in 59 patients receiving total parenteral nutrition (TPN). Inspiratory muscle strength was assessed by measuring maximal inspiratory pressure (Pm) after a tidal expiration, with the patient supine and the nose occluded. Body composition was determined by multiple isotope dilution. Body cell mass (BCM) and extracellular mass were estimated by measuring total exchangeable potassium (Ke) and total exchangeable sodium (Nae), respectively; Nae/Ke, an index of the nutritional state, was calculated from these values. The effect of changes in muscle mass was evaluated in 29 of the patients by simultaneous determination of Pm and body composition, prior to and at 2-wk intervals during TPN therapy. The Pm was lower (mean +/- 1 SE:33.5 +/- 2.8 cm H2O) in malnourished patients than in those who were in the normal Nae/Ke range (45.3 +/- 4.8 cm H2O, p less than 0.05). Loss of strength was related to reduction in muscle mass because BCM was also reduced in malnourished patients (15.6 +/- 0.8 kg) when compared to those with normal Nae/Ke (19.3 +/- 0.9 kg), (p less than 0.05), and Pm was positively correlated with BCM (r = 0.27, p less than 0.01). Changes in BCM were accompanied by appropriate changes in Pm during the study period (r = 0.44, p less than 0.01); the majority (21 patients) showed improvement in both BCM and Pm.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Composition↗

PubMed1999

Effect of testosterone treatment on body composition and muscle strength in men over 65 years of age.

As men age, serum testosterone concentrations decrease, the percentage of body mass that is fat increases, the percentage of lean body mass decreases, and muscle strength decreases. Because these changes are similar to those that occur in hypogonadal men, we hypothesized that increasing the serum testosterone concentration of men over 65 yr of age to that in young men would decrease their fat mass, increase their lean mass, and increase their muscle strength. We randomized 108 men over 65 yr of age to wear either a testosterone patch or a placebo patch in a double blind study for 36 months. We measured body composition by dual energy x-ray absorptiometry and muscle strength by dynamometer before and during treatment. Ninety-six men completed the entire 36-month protocol. Fat mass decreased (-3.0+/-0.5 kg) in the testosterone-treated men during the 36 months of treatment, which was significantly different (P = 0.001) from the decrease (-0.7+/-0.5 kg) in the placebo-treated men. Lean mass increased (1.9+/-0.3 kg) in the testosterone-treated men, which was significantly different (P < 0.001) from that (0.2+/-0.2 kg) in the placebo-treated men. The decrease in fat mass in the testosterone-treated men was principally in the arms (-0.7+/-0.1 kg; P < 0.001 compared to the placebo group) and legs (-1.1+/-0.2 kg; P < 0.001), and the increase in lean mass was principally in the trunk (1.9+/-0.3 kg; P < 0.001). The change in strength of knee extension and flexion at 60 degrees and 180 degrees angular velocity during treatment, however, was not significantly different between the two groups. We conclude that increasing the serum testosterone concentrations of normal men over 65 yr of age to the midnormal range for young men decreased fat mass, principally in the arms and legs, and increased lean mass, principally in the trunk, but did not increase the strength of knee extension and flexion, as measured by dynamometer.

Aged↗

PubMed1994

Assessment of respiratory muscle strength in the intensive care unit.

The measurement of respiratory muscle strength in the intensive care unit (ICU) is potentially useful for the prediction of weaning outcome. An easy and accurate measure would also allow investigation of respiratory muscle weakness in critically ill patients. At present, there is no satisfactory method of strength measurement in the intensive care unit. Vital capacity is a nonspecific, volitional and relatively insensitive measure of strength. True maximum respiratory pressures are difficult to achieve and, in stable patients, results vary greatly both over time and between observers. For these reasons, there are few good data of respiratory muscle strength in the intensive care unit. Of the new techniques being developed, magnetic stimulation of the phrenic nerves, combined with the measurement of transdiaphragmatic, oesophageal, or endotracheal tube pressure, offers the greatest promise.

Humans↗

PubMed2004

Effects of an alleged myostatin-binding supplement and heavy resistance training on serum myostatin, muscle strength and mass, and body composition.

This study examined 12 wk of resistance training and cystoseira canariensis supplementation on serum levels of myostatin and follistatin-like related gene (FLRG) and muscle strength and body composition. Twenty-two untrained males were randomly assigned to a placebo (PLC) or myostatin binder (MYO) group in a double-blind fashion. Blood was obtained before and after 6 and 12 wk of training. PLC and MYO trained thrice weekly using 3 sets of 6 to 8 repetitions at 85 % to 90 % 1 repetition maximum. MYO ingested 1200 mg/d of cystoseira canariensis. Data were analyzed with 2-way ANOVA. After training, total body mass, fat-free mass, muscle strength, thigh volume/mass, and serum myostatin and FLRG increased for both groups (P < 0.05); however, there were no differences between groups (P > 0.05). Twelve wk of heavy resistance training and 1200 mg/d of cystoseira canariensis supplementation appears ineffective at inhibiting serum myostatin and increasing muscle strength and mass or decreasing fat mass.

Adult↗

PubMed2006

Evaluation of respiratory muscle strength by randomized controlled trial comparing thoracoscopy, transaxillary thoracotomy, and posterolateral thoracotomy for lung biopsy.

OBJECTIVE: The aim of this study was to demonstrate that the postoperative recovery of respiratory muscle strength is better in patients who undergo video-thoracoscopy than in patients who undergo transaxillary thoracotomy or posterolateral thoracotomy. DESIGN: Randomized controlled trial with three parallel groups. STUDY POPULATION: Eligible patients had undergone wedge resection for lung biopsy in interstitial lung disease or in pulmonary nodule. Twenty-four patients were randomly assigned to one of the three thoracic procedures: eight in the video-thoracoscopy (VT) group, eight in the transaxillary thoracotomy (TT) group, and eight in the posterolateral thoracotomy (PLT) group. MEASUREMENTS: The postoperative respiratory muscle strength was assessed by maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) measured by mouth pressure. Measurements were made the day before the operation and 2, 4, and 30 days after the operation. Changes in postoperative MIP and MEP were expressed as a percentage of preoperative values. RESULTS: The three groups were comparable with respect to age, gender, comorbidity, preoperative spirometry, preoperative MIP, MEP and peak flow, and volume of lung tissue. At 2, 4, and 30 days after the operation, mean MIP were, respectively, 111+/-22%, 119+/-22%, and 124+/-22% in the VT group, 76+/-22%, 109+/-22%, and 127+/-22% in the TT group, and 51+/-22%, 50+/-22%, and 77+/-22% in the PLT group (p<0.0001). At 2, 4, and 30 days after the operation, mean MEP were, respectively, 94+/-15%, 103+/-15%, and 105+/-15% in the VT group, 61+/-15%, 98+/-15%, and 126+/-15% in the TT group, and 62+/-15%, 75+/-15%, and 87+/-15% in the PLT group (p<0.05). CONCLUSIONS: Video-thoracoscopy allows better recovery of respiratory muscle function after surgery than posterolateral thoracotomy. However, at 4 and 30 days after surgery, video-thoracoscopy and transaxillary thoracotomy gave similar results of impairment of respiratory muscle strength.

Adult↗

PubMed2003

Five years of growth hormone replacement therapy in adults: age- and gender-related changes in isometric and isokinetic muscle strength.

GH replacement therapy in adults with adult-onset GH deficiency (GHD) has been shown to increase isometric and isokinetic muscle strength in a few trials with limited numbers of patients. In this single center, prospective, open-label study, the effects of 5-yr GH replacement therapy on muscle function were determined in 109 consecutive adults (61 men and 48 women) with adult-onset GHD. The mean initial GH dose was 0.88 mg/d. The dose was gradually lowered, and after 5 yr the mean dose was 0.46 mg/d. The mean IGF-I SD score increased from -1.54 at baseline to 1.53 at study end. A sustained increase in lean body mass and decrease in body fat was observed. The GH treatment induced persistent increases in isometric knee flexor strength, concentric knee flexor strength at an angular velocity of 60 degrees/sec, and right-hand peak grip strength. After correction for age and gender using observed/predicted value ratios, a sustained increase was also observed in isometric (60 degrees) and concentric (180 degrees/sec) knee extensor strength, average right-hand grip strength for 10 sec, and left-hand grip strength. At study end, knee flexor and extensor strength was 96-104% of predicted and hand grip strength was 84-90% of predicted values. The local muscle endurance was transiently decreased after correction for age and gender. No gender difference was found in the treatment responses in muscle strength. However, muscle strength (also after correction for age and gender) was lower in women than men throughout the study period. In conclusion, GH replacement therapy in adults with adult-onset GHD normalized isometric and isokinetic knee flexor and extensor strength. Hand grip strength increased but was not fully normalized.

Adipose Tissue↗

PubMed2002

Muscle strength as a predictor of onset of ADL dependence in people aged 75 years.

The aim of this prospective study over 5 years was to examine maximal isometric strength of multiple muscle groups as a predictor of losing independence in activities of daily living (ADL). The participants were from the Nordic Research on Aging (NORA75). These analyses are restricted to 567 people who at baseline were independent in ADL and participated in strength tests, and who five years later participated in follow-up ADL assessments. Tests on maximal isometric strength of hand grip, elbow flexion, knee extension and trunk flexion and extension were done using adjustable dynamometers. For each muscle group tested, three equal groups were formed for men and women separately based on distributions of results. Those who reported being unable or needing help for eating, dressing, bathing, toileting, walking indoors or transferring from a bed or a chair were rated as ADL dependent. Of the 227 initially ADL independent men, 21 (9.3%) became dependent in ADL. In women, the figures were 30 (8.8%) of 340. Multiple logistic regression models were used to predict the risk of ADL dependence in groups based on strength tertiles. After confirming that the association of muscle strength and incident ADL-dependence was similar in men and women, both genders were included in the same analyses adjusted for body weight and height, gender and research locality. Gender specific cut-offs were used for strength tertiles. All the strength tests predicted ADL dependence, with those being in the lowest tertile having two to three times greater risks than those in the highest tertile of strength. Further adjustments for chronic diseases did not materially change the results. Strength tests could be used to identify people who are still independent in ADL but who are at increased risk of becoming dependent because of poor muscle strength, and who could reduce their risk by strengthening exercises.

Activities of Daily Living↗

PubMed2003

Changes in muscle strength and pain in response to surgical repair of posterior abdominal wall disruption followed by rehabilitation.

BACKGROUND: Posterior abdominal wall deficiency (PAWD) is a tear in the external oblique aponeurosis or the conjoint tendon causing a posterior wall defect at the medial end of the inguinal canal. It is often known as sportsman's hernia and is believed to be caused by repetitive stress. OBJECTIVE: To assess lower limb and abdominal muscle strength of patients with PAWD before intervention compared with matched controls; to evaluate any changes following surgical repair and rehabilitation. METHODS: Sixteen subjects were assessed using a questionnaire, isokinetic testing of the lower limb strength, and pressure biofeedback testing of the abdominals. After surgery and a six week rehabilitation programme, the subjects were re-evaluated. A control group were assessed using the same procedure. RESULTS: Quadriceps and hamstrings strength was not affected by this condition. A deficit hip muscle strength was found on the affected limb before surgery, which was significant for the hip flexors (p = 0.05). Before surgery, 87% of the patients compared with 20% of the controls failed the abdominal obliques test. Both the injured and non-injured sides had improved significantly in strength after surgery and rehabilitation. The strength of the abdominal obliques showed the most significant improvement over the course of the rehabilitation programme. CONCLUSIONS: Lower limb muscle strength may have been reduced as the result of disuse atrophy or pain inhibition. Abdominal oblique strength was deficient in the injured patients and this compromises rotational control of the pelvis. More sensitive investigations (such as electromyography) are needed to assess the link between abdominal oblique function and groin injury.

Abdominal Muscles↗

PubMed1996

Do genetic factors explain associations between muscle strength, lean mass, and bone density? A twin study.

Are the associations between muscle strength, lean mass, and bone mineral density (BMD) genetically determined? Based on within-pair differences in 56 monozygotic (MZ) and 56 dizygotic (DZ) female twin pairs, mean age 45 yr (range 24-67), BMD was associated with lean mass, independent of fat mass and height (P < 0.05). A 10% increment in femoral neck (FN) BMD was associated with a 15% increment in lean mass (approximately 6 kg). BMD was associated with muscle strength (measured in 35 pairs) before, but not after, adjusting for lean mass. Based on age-adjusted cross-sectional analyses, same-trait correlations (+/- SE) in MZ pairs were double those in DZ pairs: FN BMD (0.62 +/- 0.08, 0.33 +/- 0.12) and lean mass (0.87 +/- 0.03, 0.30 +/- 0.11; all P < 0.001), consistent with a genetic hypothesis. The cross-trait correlation (r) between lean mass and FN BMD in the same individual was 0.43 +/- 0.06. The cross-trait cross-twin correlation between lean mass in one twin and FN BMD in the other was 0.31 +/- 0.07 in MZ pairs, approximately 75% of the cross-trait correlation (r) and 0.19 +/- 0.09 in DZ paris (P < 0.001). After adjusting for height and fat mass, the MZ and DZ cross-trait cross-twin correlations were no different (0.16 +/- 0.08 and 0.13 +/- 0.09, respectively). Therefore, genetic factors account for 60-80% of the individual variances of both FN BMD and lean mass, and > 50% of their covariance. The association between greater muscle mass and greater BMD is likely to be determined by genes regulating size.

Adult↗

PubMed2002

The effectiveness of aerobic and muscle strength training in patients receiving hemodialysis and EPO: a randomized controlled trial.

BACKGROUND: Individuals with end-stage renal disease on hemodialysis therapy have reduced aerobic exercise capacity and reduced muscle strength. METHODS: This was a single-blind, randomized, placebo-controlled trial of an exercise intervention in hemodialysis patients administered erythropoietin. The intervention consisted of progressive resisted isotonic quadriceps and hamstrings exercise and training on a cycle ergometer three times weekly for 12 weeks. Individuals in the control group underwent a nonprogressive program of range-of-motion exercises. Both groups were observed for an additional 5 months without intervention. Outcomes were assessed without knowledge of treatment assignment at baseline, 12 weeks, and 5 months. A healthy age- and sex-matched sample provided comparative data. RESULTS: Our sample was relatively high functioning, with a mean score on the Physical Function subscale of the Short Form 36 (SF-36) of 76 of 100. At 12 weeks, there were large and statistically significant differences in favor of the experimental group on the submaximal exercise test (14 W; 95% confidence interval, 2 to 26) and muscle strength (45 lb; 95% confidence interval, 9 to 81), but not in the 6-minute walk, symptoms questionnaire, or SF-36. Differences between the intervention and control groups at 12 weeks were not evident on retesting 5 months after the end of the intervention. Compared with the healthy sample, patients were significantly lower functioning on the submaximal exercise test, muscle strength, and 6-minute walk test at baseline. CONCLUSION: In this high-functioning sample, the exercise program improved physical impairment measures, but had no effect on symptoms or health-related quality of life. The impact on patients with a greater degree of physical dysfunction needs to be rigorously studied.

Anemia↗