Kynurenine aminotransferase isoforms display fiber-type specific expression in young and old human skeletal muscle.

Conversion of kynurenine (KYN) to kynurenic acid (KYNA) is the main pathway for free tryptophan degradation in skeletal muscle and has emerged as an important mechanism of how exercise is linked to promotion of mental health. Metabolism of KYN to KYNA mainly depends on the expression of kynurenine aminotransferases (KATs) that is under control of the mitochondria biogenesis regulator PGC-1α. We therefore hypothesized that expression of KATs would vary between muscle fibers that differ in mitochondrial content, i.e. oxidative type I vs more glycolytic type II muscle fibers. Moreover, we tested the hypothesis that KAT expression differs with age. Single muscle fibers were isolated from biopsies taken from the vastus lateralis muscle in young and old healthy subjects. In young and old subjects the abundance of KAT I, KAT III and KAT IV was greater in Type I than Type II fibers without age-dependent difference in the KAT isoform expressions. The link to mitochondrial content was further seen as the expression of KAT IV correlated to mitochondrial cytochrome c oxidase IV (COX IV) abundance in both fiber types. In conclusion, we describe for the first time the expression pattern of KAT isoforms with respect to specific fiber types and age in human skeletal muscle.

Circulating levels of dickkopf-1, osteoprotegerin and sclerostin are higher in old compared with young men and women and positively associated with whole-body bone mineral density in older adults.

Bone mineral density declines with increasing older age. We examined the levels of circulating factors known to regulate bone metabolism in healthy young and older adults. The circulating levels of dickkopf-1, osteocalcin, osteoprotegerin and sclerostin were positively associated with whole-body bone mineral density (WBMD) in older adults, despite the average WBMD being lower and circulating dickkopf-1, osteoprotegerin and sclerostin being higher in old than young. INTRODUCTION: This study aims to investigate the relationship between whole-body bone mineral density (WBMD) and levels of circulating factors with known roles in bone remodelling during 'healthy' ageing. METHODS: WBMD and fasting plasma concentrations of dickkopf-1, fibroblast growth factor-23, osteocalcin, osteoprotegerin, osteopontin and sclerostin were measured in 272 older subjects (69 to 81 years; 52% female) and 171 younger subjects (18-30 years; 53% female). RESULTS: WBMD was lower in old than young. Circulating osteocalcin was lower in old compared with young, while dickkopf-1, osteoprotegerin and sclerostin were higher in old compared with young. These circulating factors were each positively associated with WBMD in the older adults and the relationships remained after adjustment for covariates (r values ranging from 0.174 to 0.254, all p < 0.01). In multivariate regression, the body mass index, circulating sclerostin and whole-body lean mass together accounted for 13.8% of the variation with WBMD in the older adults. In young adults, dickkopf-1 and body mass index together accounted for 7.7% of variation in WBMD. CONCLUSION: Circulating levels of dickkopf-1, osteocalcin, osteoprotegerin and sclerostin are positively associated with WBMD in community-dwelling older adults, despite the average WBMD being lower and circulating dickkopf-1, osteoprotegerin and sclerostin being higher in old than young.

The prevalence of malnutrition according to the new ESPEN definition in four diverse populations.

BACKGROUND & AIMS: Consensus on the definition of malnutrition has not yet been reached. Recently, The European Society for Clinical Nutrition and Metabolism (ESPEN) proposed a consensus definition of malnutrition. The aim of the present study was to describe the prevalence of malnutrition according to the ESPEN definition in four diverse populations. METHODS: In total, 349 acutely ill middle-aged patients, 135 geriatric outpatients, 306 healthy old individuals and 179 healthy young individuals were included in the study. Subjects were screened for risk of malnutrition using the SNAQ. The ESPEN definition of malnutrition, i.e. low BMI (< 18.5 kg/m(2)) or a combination of unintentional weight loss and low FFMI or low BMI was applied to all subjects. RESULTS: Screening identified 0, 0.5, 10 and 30% of the healthy young, the healthy old, the geriatric outpatients and the acutely ill middle-aged patients as being at risk of malnutrition. The prevalence of malnutrition ranged from 0% in the healthy young, 0.5% in healthy old individuals, 6% in the geriatric outpatients to 14% in the acutely ill middle-aged patients. Prevalence of low FFMI was observed in all four populations (14-33%), but concurred less frequently with weight loss (0-13%). CONCLUSIONS: Using the ESPEN definition, 0%-14% malnutrition was found in the diverse populations. Further work is needed to fully address the validity of a two-step approach, including risk assessment as an initial step in screening and defining malnutrition. Furthermore, assessing the predictive validity of the ESPEN definition is needed.

Serum albumin and muscle measures in a cohort of healthy young and old participants.

Consensus on clinically valid diagnostic criteria for sarcopenia requires a systematical assessment of the association of its candidate measures of muscle mass, muscle strength, and physical performance on one side and muscle-related clinical parameters on the other side. In this study, we systematically assessed associations between serum albumin as a muscle-related parameter and muscle measures in 172 healthy young (aged 18-30 years) and 271 old participants (aged 69-81 year) from the European MYOAGE study. Muscle measures included relative muscle mass, i.e., total- and appendicular lean mass (ALM) percentage, absolute muscle mass, i.e., ALM/height(2) and total lean mass in kilograms, handgrip strength, and walking speed. Muscle measures were standardized and analyzed in multivariate linear regression models, stratified by age. Adjustment models included age, body composition, C-reactive protein and lifestyle factors. In young participants, serum albumin was positively associated with lean mass percentage (p = 0.007) and with ALM percentage (p = 0.001). In old participants, serum albumin was not associated with any of the muscle measures. In conclusion, the association between serum albumin and muscle measures was only found in healthy young participants and the strongest for measures of relative muscle mass.

Associations between muscle strength, spirometric pulmonary function and mobility in healthy older adults.

Pathological obstruction in lungs leads to severe decreases in muscle strength and mobility in patients suffering from chronic obstructive pulmonary disease. The purpose of this study was to investigate the interdependency between muscle strength, spirometric pulmonary functions and mobility outcomes in healthy older men and women, where skeletal muscle and pulmonary function decline without interference of overt disease. A total of 135 69- to 81-year-old participants were recruited into the cross-sectional study, which was performed as a part of European study MyoAge. Full, partial and no mediation models were constructed to assess the interdependency between muscle strength (handgrip strength, knee extension torque, lower extremity muscle power), spirometric pulmonary function (FVC, FEV1 and FEF50) and mobility (6-min walk and Timed Up and Go tests). The models were adjusted for age, sex, total fat mass, body height and site of enrolment. Partial mediation models, indicating both direct and pulmonary function mediated associations between muscle strength and mobility, fitted best to the data. Greater handgrip strength was significantly associated with higher FVC, FEV1 and FEF50 (p < 0.05). Greater muscle power was significantly associated with better performance in mobility tests. Results suggest that decline in mobility with aging may be caused by decreases in both muscle strength and power but also mediated through decreases in spirometric pulmonary function. Future longitudinal studies are warranted to better understand how loss of function and mass of the respiratory muscles will affect pulmonary function among older people and how these changes are linked to mobility decline.

Diagnostic criteria for sarcopenia and physical performance.

Relative and absolute muscle mass and muscle strength are used as diagnostic criteria for sarcopenia. We aimed to assess which diagnostic criteria are most associated with physical performance in 180 young (18-30 years) and 281 healthy old participants (69-81 years) of the European study MYOAGE. Diagnostic criteria included relative muscle mass (total or appendicular lean mass (ALM) as percentage of body mass), absolute muscle mass (ALM/height squared and total lean mass), knee extension torque, and handgrip strength. Physical performance comprised walking speed, Timed Up and Go test (TUG), and in a subgroup physical fitness. Diagnostic criteria for sarcopenia and physical performance were standardized, and the associations were analyzed using linear regression models stratified by age category, with adjustments for age, gender, and country. In old participants, relative muscle mass was associated with faster walking speed, faster TUG, and higher physical fitness (all p < 0.001). Absolute muscle mass was not associated with physical performance. Knee extension torque and handgrip strength were associated with faster walking speed (both p ≤ 0.003). Knee extension torque was associated with TUG (p = 0.001). Knee extension torque and handgrip strength were not associated with physical fitness. In young participants, there were no significant associations between diagnostic criteria for sarcopenia and physical performance, except for a positive association between relative muscle mass and physical fitness (p < 0.001). Relative muscle mass, defined as lean mass or ALM percentage, was most associated with physical performance. Absolute muscle mass including ALM/height squared was not associated with physical performance. This should be accounted for when defining sarcopenia.

Shoulder muscle function in frozen shoulder syndrome patients following manipulation under anesthesia: a 6-month follow-up study.

INTRODUCTION: The present study evaluates changes in shoulder muscle function in patients with frozen shoulder syndrome (FSS) following manipulation under general anesthesia (MUA). PATIENTS AND METHODS: Fifteen FSS patients with mean (±SD) age of 53.6±9.7 years were included in this study. Isometric endurance of the shoulder muscles was characterized by time and net impulse (NI), which were assessed with the patient holding a weight in the hand until exhaustion. Fatigability of the deltoid and trapezius muscles during isometric endurance test was assessed by electromyogram power spectrum median frequency (MF) slope per minute. Patients were also screened for daytime pain. Data were collected before MUA, and at 1 and 6 months postoperatively. RESULTS: Six months postoperatively, the MF slope for the trapezius and deltoid muscles of the involved and uninvolved shoulders did not differ (P>0.05), whereas NI remained lower and endurance time was longer (P<0.05). Shoulder pain was reduced as compared to preoperative levels (on visual analog scale) 1 and 6 months postoperatively (P<0.05). DISCUSSION: In patients with FSS, the fastest improvements in shoulder muscle NI, fatigability and pain take place in the first month after MUA; 6 months after MUA, however, NI and endurance time remained impaired for the involved shoulder. Physiotherapy should pay more attention to muscle function recovery. LEVEL OF EVIDENCE: Level III, prospective follow-up study.

Diagnostic measures for sarcopenia and bone mineral density.

SUMMARY: Currently used diagnostic measures for sarcopenia utilize different measures of muscle mass, muscle strength, and physical performance. These diagnostic measures associate differently to bone mineral density (BMD), as an example of muscle-related clinical outcome. These differences should be taken into account when studying sarcopenia. INTRODUCTION: Diagnostic measures for sarcopenia utilize different measures of muscle mass, muscle strength, and physical performance. To understand differences between these measures, we determined the association with respect to whole body BMD, as an example of muscle-related clinical outcome. METHODS: In the European cross-sectional study MYOAGE, 178 young (18-30 years) and 274 healthy old participants (69-81 years) were recruited. Body composition and BMD were evaluated using dual-energy X-ray densitometry. Diagnostic measures for sarcopenia were composed of lean mass as percentage of body mass, appendicular lean mass (ALM) as percentage of body mass, ALM divided by height squared (ALM/height(2)), knee extension torque, grip strength, walking speed, and Timed Up and Go test (TUG). Linear regression models were stratified for sex and age and adjusted for age and country, and body composition in separate models. RESULTS: Lean mass and ALM/height(2) were positively associated with BMD (P < 0.001). Significance remained in all sex and age subgroups after further adjustment for fat mass, except in old women. Lean mass percentage and ALM percentage were inversely associated with BMD in old women (P < 0.001). These inverse associations disappeared after adjustment for body mass. Knee extension torque and handgrip strength were positively associated with BMD in all subgroups (P < 0.01), except in old women. Walking speed and TUG were not related to BMD. CONCLUSIONS: The associations between diagnostic measures of sarcopenia and BMD as an example of muscle-related outcome vary widely. Differences between diagnostic measures should be taken into account when studying sarcopenia.

Low back muscle fatigue during Sørensen endurance test in patients with chronic low back pain: relationship between electromyographic spectral compression and anthropometric characteristics.

This study assessed low back muscle fatigue during Sørensen back endurance test in chronic low back pain (CLBP) patients and healthy controls, and investigated relationship between the erector spinae muscle fatigability and subject's anthropometric characteristics. Four groups (n = 10 per group) of middle-aged (47-52-year-old) subjects participated: 1) female CLBP patients, 2) healthy female subjects, 3) male CLBP patients and 4) healthy male subjects. Subjects performed Sørensen back endurance test until exhaustion, while electromyographic (EMG) power spectrum median frequency compression over time (MF slope) as indicator of the erector spinae muscle fatigability, and endurance time were recorded. The endurance time was shorter (p < 0.05) in male CLBP patients compared to the healthy male and female subjects. No significant gender differences in endurance time were found in CLBP patients and in healthy subjects. EMG power spectrum MF slope did not differ significantly in CLBP patients and in healthy subjects. However, MF slope was higher (p < 0.05) in healthy male than in female subjects. Body mass and BMI correlated moderately positively with MF slope (r = 0.40-0.67) in all measured groups. We conclude that male CLBP patients had lower back extensor muscle isometric endurance compared to the healthy subjects of both genders, whereas no gender differences in isometric endurance were found in CLBP patients and in healthy subjects. Healthy male subjects had greater lumbar erector spinae muscle fatigability compared to the healthy female subjects. Subjects with higher body mass and body mass index fatigued faster during Sørensen back endurance test.

Changes in soleus motoneuron pool reflex excitability and surface EMG parameters during fatiguing low- vs. high-intensity isometric contractions.

The fatigue-related changes in soleus motoneuron pool reflex excitability and surface electromyography (EMG) parameters, and maximal voluntary contraction (MVC) force of the plantarflexor (PF) muscles during repeatedly sustained low- (30% MVC) vs. high-intensity (70% MVC) isometric contractions were evaluated Twelve young men with mean (+/- SE) age of 22.4 +/- 0.3 years participated in two fatigue tasks on separate days with at least 1-week interval. The fatigue task consisted of three sustained isometric contractions of PF muscles at a target force level until exhaustion separated with 2-min pause between contractions. M-wave (muscle compound action potential) amplitude (M(max)), Hoffmann reflex maximal amplitude (H(max)) to M-wave amplitude ratio (H(max)/M(max)), and root mean square amplitude (RMS) and median frequency (MF) of EMG power spectrum were recorded from the soleus muscle. The M(max) remained constant immediately post-fatigue and during recovery for low- and high-intensity fatigue tasks, whereas H(max)/M(max) was significantly (p < 0.05) reduced only after high-intensity fatigue task. The increase in RMS and decrease in MF during isometric contractions, and reduction in MVC force immediately after the exercise was greater (p < 0.05) for low-intensity fatigue task. We conclude that low-intensity isometric contractions, repeatedly sustained to fatigue, resulted in a marked increase in the EMG amplitude and spectral compression without a significant post-fatigue reflex inhibition of soleus motoneuron pool. High-intensity contractions, however, resulted in post-fatigue reflex inhibition of soleus motoneuron pool and less pronounced EMG spectral compression during fatiguing contractions. A failure of neuromuscular transmission-propagation was not evident after repetitive fatiguing isometric contractions.

Rod-through-plate fixation of canine diaphyseal fractures.

UNLABELLED: Efficacy of the rod-through-plate fixation for fracture repair was evaluated in six clinical cases of canine long bone fractures. This fixation incorporates principles of intramedullary and extramedullary osteosynthesis for transverse and short oblique fractures of long tubular bones. The plate-through-rod device is comprised of one pair of curved rods, a connecting plate and two bone screws. The connecting plate has both a hole and a channel on each end. Curved rods have a long curved part and a straight part with a hole in it for screw fixation. All components are made up of medical stainless steel. Clinical and radiographical examinations were performed from week seven to18 months after the operation. Functional abnormalities were not observed at this period in five patients and all fractures were healed. In one patient screw stripping in the proximal fragment of the femur was detected radiologically and minimal implant dislocation was noted at seven weeks after the initial repair. The rod-through-plate fixation method gives strong fixation of bone fragments with minimal traumatization of soft tissue during the operation. The design of the rod-through-plate is intended to reduce pressure of the plate on the cortex in the area of the fracture, whereas the dynamic fixation provided by the intramedullary rods may allow micromotion, thus stimulating callus formation and avoiding implant-induced osteoporosis. CLINICAL RELEVANCE: The rod-through-plate fixator has a simple construction and its use expands the treatment possibilities for diaphyseal fractures of long bones.

Shoulder muscle strength and fatigability in patients with frozen shoulder syndrome: the effect of 4-week individualized rehabilitation.

The effect of 4-week individualized rehabilitation on shoulder muscle strength and fatigability was evaluated in 10 patients with frozen shoulder syndrome (FSS) in comparison of 10 age- and gender-matched healthy control subjects. Isometric maximal voluntary contraction (MVC) force of the shoulder flexors was measured by hand-held dynamometer. Isometric endurance of the shoulder muscles was characterized by endurance time and net impulse (NI) assessed during weight (30% MVC) holding in hand until exhaustion. Fatigability of deltoideus, infraspinatus and trapezius muscles during isometric endurance test was assessed by electromyogram (EMG) power spectrum median frequency (MF) slope per minute. Rehabilitation in patients with FSS consisted of exercise therapy in swimming pool and gymnasium, electrical therapy and massage. Before rehabilitation, patients with FSS had less (p < 0.05) isometric MVC force and NI during endurance test compared to the control. MF slope in patients with FSS for involved extremity was higher (p <0.05) for the deltoideus muscle and less for the infraspinatus muscle before rehabilitation compared to the controls. Shoulder pain was decreased (p < 0.05) and isometric MVC force and NI in endurance test in patients for involved extremity were increased after rehabilitation. No significant changes in endurance time and MF slope for infraspinatus and trapezius muscles in patients for involved extremity were observed after rehabilitation, whereas MF slope for deltoideus muscle was increased. It was concluded that in patients with FSS, 4-week rehabilitation decreased shoulder pain and improved MVC force of the shoulder flexors and isometric working capacity of these muscles during endurance test.

Integrative re-organization mechanism for reducing tremor in Parkinson's disease patients.

A special movement therapy, called coordination dynamics therapy, has been reported to have the potential to improve central nervous system (CNS) functioning in Parkinson's disease patients. Electromyography using surface electrodes (sEMG) showed that the rhythmic muscle activity leading to Parkinsonian tremor was generated in the patients by the impairment of two kinds of inhibition. First, some premotor spinal oscillators organized themselves in the CNS neuronal networks without strong adequate input and second, the oscillators synchronized their firing to give rise to rhythmic muscle activity and tremor. In this paper it will be shown that highly coordinated arm and leg movements, generated when exercising on a special coordination dynamics therapy device, can reduce Parkinsonian tremor in amplitude and frequency and improve CNS functioning in the short-term memory. sEMG measurements showed upon exercising on the special coordination dynamics therapy device that the motor program improved in the short-term memory and tremor muscle activity became coordinated with the volitional motor program and reduced in size and frequency. Higher load exercising seemed to better reduce tremor muscle activity, probably because the physiologic CNS organization was more integrative then and could 'bind' stronger simultaneous pathologic tremor activity. Moreover, the rhythmic synchronized motor unit firing in different arm and leg muscles was synchronized or coordinated and changed in frequency and amplitude. It is concluded that the integrative re-organization mechanism to reduce Parkinsonian tremor is the phase and frequency coordination between neuron firing of the physiologic neuronal network state, generated by the highly coordinated arm and leg movements, and the simultaneous pathologic tremor network state, generated by the uninhibited neurons, firing synchronized oscillatory.

Improvement in Parkinson's disease patients achieved by coordination dynamics therapy.

Eight patients in whom Parkinson's disease had set on 5 to 10 years earlier underwent low intensity coordination dynamics therapy with on average 4 hours per week for 2.5 months. The ongoing pharmaco-therapy and the conventional fitness training for 1 to 2 hours per week were not changed. With the coordination dynamics therapy the functioning of the central nervous system (CNS) of the Parkinson's disease patients improved by 35%, as quantified by coordination dynamics measurements. Following 3 months of no coordination dynamics therapy, but further ongoing pharmaco-therapy and fitness training the CNS functioning worsened again by 21%. It is concluded that pharmaco-therapy and conventional fitness training alone cannot prevent the worsening of the CNS functioning in progressing Parkinson's disease, but additional coordination dynamics therapy can.

High-load coordination dynamics in athletes, physiotherapists, gymnasts, musicians and patients with CNS injury.

High-load coordination dynamics were measured in athletes, physiotherapists, gymnasts, musicians, patients with spinal cord injury and a patient with multiple sclerosis during exercise on a special coordination dynamic therapy device to quantify improvement in the central nervous system (CNS) organization due to therapy in patients and to quantify differences in the CNS organization between healthy subjects and patients with CNS injury. The values of high-load coordination dynamics for the group of athletes were two times better than those of physiotherapists, gymnasts and musicians, but still two times poorer than the best value achieved so far in a patient with a spinal cord injury after 10 months of continuous intensive coordination dynamics therapy. Especially the physiotherapists, gymnasts and musicians had poor coordination between arms and legs for the difficult intermediate coordinations between pace and trot gait for high load. Exhaustion of the CNS and improvement of CNS functioning in the short-term memory could be made visible using hysteresis-like curves for load increase and decrease. When not receiving therapy, patients with CNS injury could not turn at high loads, and showed poor coordination at lower loads only. After exercising 7,000 coordinated arm and leg movements per month, the CNS organization for high load improved in 3 healthy subjects by 36%. In patients with CNS injury, such improvements of high-load coordination dynamics took several months of intensive coordination dynamics therapy including 350,000 coordinated movements per months. The rate of learning may differ in healthy subjects and patients very approximately by a factor of 50 depending on the severity of the injury. On the other hand however, the high-load coordination between arms and legs, necessary for walking could be improved during therapy even in patients with multiple sclerosis, with the consequence that they could manage better in every day life.

Low-load coordination dynamics in athletes, physiotherapists, gymnasts, musicians and patients with spinal cord injury, after stroke, traumatic brain lesion and with cerebral palsy.

Low-load coordination dynamics were measured in athletes, physiotherapists, gymnasts, musicians and patients after stroke, traumatic brain injury and spinal cord lesion during exercise on a special coordination dynamic therapy device to quantify differences in central nervous system (CNS) organization between healthy subjects and patients with CNS injury. In healthy humans coordination dynamics (arrhythmicity of turning) varied between 5.2 and 6.0 for forward and between 6.9 and 10.7 1/s for backward turning. The frequency of turning varied between 1.24 (athletes) and 1.49 Hz (musicians) for forward and between 1.11 and 1.25 Hz for backward turning. Apart from the poor rhythmicity of backward turning among physiotherapists, gymnasts and musicians, inter-group differences were small in comparison to intra-group variation. In patients with spinal cord lesion the coordination dynamics value was 8.3 for forward and 11.0 for backward turning. The frequencies for forward and backward turning were 1.20 and 1.20 Hz respectively. The values for coordination dynamics and frequency of turning thus did only slightly differ from those measured for healthy subjects. The patients after stroke, traumatic brain injury and cerebral palsy had much higher coordination dynamic values (20.4, 22.9 and 30 1/s respectively) and lower forward (0.85, 0.93, and 0.52 Hz) and backward turning frequencies (0.98, 1.06, 0.42 Hz), suggesting strongly pathologic CNS organization. Low-load coordination dynamics (20N) are thus useful to measure progress in CNS organization due to therapy in patients with CNS injury.

Coordination dynamics in Parkinson's disease patients and healthy subjects quantified by the coordination dynamics recording method and sEMG.

Coordination dynamics were measured in Parkinson's disease patients to quantify central nervous system (CNS) dysfunction. The low-load coordination dynamics in the patients were impaired by 56% for forward and 44% for backward moving in comparison to a control group of similar age. Exercising at higher load was only partly possible. When the disease preferentially affected one side of the body, the coordination dynamics were worse for the affected side. A dexterity test showed that coordination of hand and arm movements could be improved in the short-term memory when exercising on the special coordination dynamics recording and therapy device. Simultaneously taken surface EMG (sEMG) showed that the motor pattern was impaired in the Parkinson's disease patients. sEMG recordings showed further that the fast fatigable muscle fibre activation was impaired. FF-type muscle fibres were already activated for low load in one and not at all in another muscle. In conclusion, coordination between motoneuron firings and between arm and leg movements were found to be impaired in Parkinson's disease patients.

Age-related differences in knee extension rate of isometric force development and vertical jumping performance in women.

AIM: The purpose of this study was to compare knee extension rate of isometric force development and vertical jumping performance characteristics in young, middle-aged and elderly women. METHODS: Unilateral knee extension maximal rate of isometric force development (RFD) was measured by a dynamometer. Maximal squat (SJ) and counter-movement jumps (CMJ) were performed on a force platform. Twelve young (21- to 24-year-old), 12 middle-aged (50- to 58-year-old) and 13 elderly (70- to 76-year-old) women participated. RESULTS: Young women had greater (p<0.05) maximal isometric RFD as compared to older groups. No significant differences in maximal isometric RFD between middle-aged and elderly women have been found. The jumping height in SJ and CMJ was greater in young women as compared to older groups, and in middle-aged women greater as compared to elderly women. Absolute and body mass-related values of CMJ height was greater as compared to SJ height only in young women. Young women had greater jumping height relative to body mass in SJ and CMJ than the other groups. CONCLUSION: The ability to develop isometric force of the knee extensor muscles rapidly did not differ significantly in middle-aged and elderly women. Middle-aged and elderly women had a reduced ability to use the potentiating effect of stretch-shortening cycle to vertical jumping performance during CMJ.

Effects of creatine supplementation during recovery from rapid body mass reduction on metabolism and muscle performance capacity in well-trained wrestlers.

BACKGROUND: The aim of the study was to test the hypothesis that creatine supplementation with concomitant carbohydrate ingestion during recovery period after rapid body mass reduction accelerates the restoration of body mass and physical performance in well-trained wrestlers. METHODS: A double-blind, placebo-controlled cross-over study was conducted on five young healthy male wrestlers, who reduced their body mass by 4.5-5.3% in two series of investigations separated by one month. During 17 hrs recovery period they consumed controlled diet supplemented in random order with glucose (GL trial) or with glucose plus creatine (GL+CR trial). The capacity of the subjects to perform submaximal and maximal (W(max)) intensity work was measured using 5 min intermittent intensity test exercise at the Cybex II device before (Test 1) and after body mass loss (Test 2), also after the recovery (Test 3) on both trials. RESULTS: There was no effect of treatment on the extent of body mass regain during 17 hrs recovery. A significant increase (19.2%) in W(max) from Test 2 to Test 3 was observed in GL+CR trial whereas no change was evident with GL treatment. A strong correlation (r=0.92) was established between the whole body creatine retention and the extent of change in W(max) from Test 2 to Test 3. CONCLUSIONS: The results suggest that creatine supplementation with concomitant glucose ingestion during 17 hrs recovery from rapid body mass loss does not accelerate the restoration of body mass but still stimulates the regain of physical performance in maximal intensity efforts in well-trained wrestlers.

Back extensor muscle fatigability in chronic low back pain patients and controls: Relationship between electromyogram power spectrum changes and body mass index.

Back extensor muscle fatigability and its relationship to body mass index (BMI) was measured in 12 chronic nonspecific low back pain (CNLBP) patients (7 women and 5 men) and 12 healthy age-and gender-matched controls. Subjects performed Sørensen back isometric endurance test until exhaustion while EMG spectral mean power frequency (MPF) over the lumbar erector spinae muscle and endurance time were recorded. The CNLBP patients had significantly shorter endurance time than healthy controls. Spectral MPF significantly declined as time of isometric contraction progressed. Relative decrease of the MPF per minute (MPF slope) for left and right side, and pooled MPF slope was significantly higher in CNLBP patients compared with controls. In CNLBP patients the isometric endurance time correlated significantly negatively with BMI (r=-0.71). In controls BMI correlated significantly positively with MPF slopes of left (r=0.68) and right (r=0.57) side, and pooled MPF slope (r=0.62).