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PubMed2006

Risk factors and musculoskeletal complaints in non-specialized nurses, IC nurses, operation room nurses, and X-ray technologists.

OBJECTIVES: To gain more insight into the prevalence rates of musculoskeletal complaints of neck-shoulder and low back and to determine the relation between physical and psychosocial work-related risk factors and the complaints mentioned in non-specialized nurses, operation room nurses, Intensive Care (IC) nurses and X-ray technologists. METHODS: The study population consists of 3,169 employees affiliated to eight university hospitals in the Netherlands. The study was conducted using a cross-sectional survey design. The parameters under study were having or having had (severe) low back or neck-shoulder complaints during the past year. In logistic regression analyses odds ratio's and CI 95% were estimated for all relevant risk factors for each of the four professional groups. RESULTS: In all groups prevalence rates of musculoskeletal complaints were high: low back 76%, neck-shoulder 60%. Operation room nurses perceived more neck-shoulder complaints (12 months prevalence) than non-specialized nurses and IC nurses perceived less severe low back complaints than non-specialized nurses. Four physical risk factors and one psychosocial factor were associated with low back complaints in all groups. CONCLUSIONS: The results of the present study indicate that both low back complaints and neck-shoulder complaints are major health problems in the four professional groups under study. The prevalence rate of neck-shoulder complaints in operation room nurses is higher than in non-specialized nurses and IC nurses, the latter groups having high prevalence rates already. The exposure to risk factors is perceived differently by each of the professional groups. The professional groups under study all are target for preventive interventions; these interventions need to be specified for each of the professional groups.

Adult↗
PubMed2000

Can a battery of functional and sensory tests corrobrate the sensorineural complaints of subjects working with vibrating tools?

OBJECTIVES: The objective of the present paper is to study the relationship between the early sensorineural symptoms, classified according to the Stockholm scale, and the results of the main functional and sensory tests described in the literature, in subjects working with vibrating tools. METHODS: Three groups of male workers were selected from industry: one group (69 subjects) exposed to hand-arm vibration in several workplaces, one group (62) performing heavy and repetitive hand and arm work but without exposure to vibration, and one control group (46) performing light and non-repetitive tasks without vibration. All the workers were interviewed by questionnaire, about their personal characteristics, their health status, their actual and past working conditions and the episodes of tingling at the level of the fingers. From these reported symptoms, the sensorineural stage of the hand-arm vibration was determined using the Stockholm scale. Based on the review of the literature, we selected six functional and sensory tests: maximum voluntary grip force, maximum angles of the wrist, pressure perception threshold test, vibration perception threshold test, distal sensory latency and the Purdue Pegboard test. Each test was performed by the workers in the three groups. RESULTS: No main differences were observed between the personal characteristics of the three groups. According to the Stockholm scale, the sensorineural symptoms were mainly at stage SN1, with 9% at stage SN2 and none at stage SN3. These symptoms are associated with exposure to vibration, and had a prevalence of 40% in group 1, versus 20% in the two other groups. Furthermore, 25% of the workers exposed to vibration complained of symptoms at least once a week, compared with only 2% in the other groups. The multivariate logistic regression analysis showed an association between the existence of symptoms and a decrease in the maximum flexion angle of the wrist and an increase in the pressure perception threshold. This association, however, was too low to determine limit values with a sensitivity and specificity sufficiently high to make a reliable diagnosis. CONCLUSIONS: The sensorineural symptoms at stage N1 on the Stockholm scale, experienced occasionally by some 40% of the users of vibrating tools, could not be corroborated by the functional and sensory tests.

Adult↗
PubMed1997

Hand-arm symptoms related to impact and nonimpact hand-held power tools.

Hand and arm symptoms among workers using impact and non-impact hand-held power tools were investigated in a cross-sectional study and a 5-year follow-up study. The study population consisted of concrete workers (n = 103), truck assemblers (n = 234), electricians (n = 101), platers (n = 140) and lumberjacks (n = 102). Of the original 680 subjects, we followed up 312 after 5 years. A questionnaire concerning ongoing hand and arm symptoms, daily exposure to hand-held power tools, type of tool used, and individual factors was administered. More workers using low-frequency impact tools than workers using non-impact tools reported symptoms in the elbows and shoulders. Elbow symptoms were accentuated in the cross-sectional study, while shoulder symptoms were accentuated in the follow-up study. Wrist symptoms were reported by more of those working with high-frequency impact tools than of those using only non-impact tools when the analyses were controlled for age, years in the occupation and smoking habits. A possible explanation of the results found in this study is that low-frequency impact vibration is transmitted to the upper arm, and thus the elbow and shoulder are at risk, while high-frequency impact vibration is attenuated in the hand and wrist and may predominantly cause symptoms there.

Arm Injuries↗
PubMed1997

Proposal for hand-arm vibration exposure limits adopted for Japanese workers operating hand-held vibration tools.

On the basis of data presented in our previous, reports, the current study was undertaken to estimate frequency-weighted hand-arm vibration exposure limits for various daily exposure times. The procedures for the present study were as follows. (1) The prevalence of vibration-induced white finger (VWF) as well as the vibration exposure were investigated in various groups of workers operating hand-held vibrating tools. The vibration magnitude of various tools was measured and the results were presented as the energy-equivalent frequency-weighted root-mean-square (m/s2 rms) acceleration. There was a statistically significant positive correlation between the prevalence of VWF and the measured vibration magnitude (R2 = 0.5, P < 0.05). Hence, it was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be considered. (2) By a careful selection of available publications which contain useful information on duration of vibration exposure of < or = 2 h/day and the occurrence of VWF, a significant correlation between the prevalence of VWF and the vibration magnitude could be observed. The regression equation was estimated as: y = -18.5 + 4.6 (x), R2 = 0.8. On the basis of this equation, it was speculated that the prevalence of VWF in workers using vibrating tools might be restricted to the prevalence of Raynaud's phenomenon in the Japanese general population if the 2-h daily vibration exposure is about 4.5 m/s2 rms. (3) Regarding this speculation, the equation provided in the documentation of ISO 5349 was used and modified as: [alpha h,w)eq,t = (alpha h,w)eq,2(2/t)1/2 (m/s2 rms)] and then the vibration limit values for daily exposure of 1 min to 8 h were calculated. (4) In order to achieve compatibility with standards of other countries, and to formulate an easy method for using the recommended values presented here, the daily exposure time of 8, 4, 2, 1 and 0.5 h were selected. The correspondence vibration magnitudes were in the range 22-9.0 m/s2 rms, and the lower limit (2.2 m/s2 rms) was assumed as the permissible vibration exposure limit for an 8-h working period. The proposed daily vibration limits were then compared with those recommended by other institutions.

Adult↗
PubMed1998

Vibration sense in the upper limb in patients with repetitive strain injury and a group of at-risk office workers.

OBJECTIVES: To investigate in patients with repetitive strain injury (RSI) and in office workers using computer keyboard equipment (a) whether the vibration threshold in the hand was altered, (b) the immediate effects of keyboard use on vibration thresholds and (c) whether the tolerance of suprathreshold vibration was normal. METHOD: A vibrametre (Somedic Ab, Stockholm Sweden) was used to obtain threshold vibration measurements, by the method of limits, for all peripheral-nerve cutaneous distributions in the hand. Tolerance of suprathreshold stimulation was obtained by stimulation of the soft tissues of the forearm by increasing the amplitude of vibration. RESULTS: Thresholds for vibration were significantly raised for the median nerve in both the patient and office-worker groups. The patient group additionally had raised thresholds for the ulnar nerve. Following use of the keyboard, thresholds for the median nerve were further elevated in the patient group, but not in the other groups, demonstrating a work-related exacerbation. At suprathreshold stimulation. 14 members (82%) of the patient group experienced an allodynic response to vibration, indicating, possible changes in the central processing of non-noxious sensory information. This changed sensory response was not seen in either the office-worker or control groups. CONCLUSION: Patients may have a minor polyneuropathy, whereas the office workers demonstrate early signs of the condition. Quantitative measurement of vibration perception may prove useful in patient assessment and for detection of the early onset of RSI in the work environment.

Adult↗
PubMed1999

Thermal thresholds, vibrotactile thresholds and finger systolic blood pressures in dockyard workers exposed to hand-transmitted vibration.

OBJECTIVES: To quantify neurological dysfunction in workers exposed to hand-transmitted vibration using alternative neurological tests. To relate the neurological findings to the results of vascular tests and the symptoms reported by subjects with vibration-induced white finger. METHODS: Thermal thresholds (for perception of heat and cold), vibrotactile thresholds (for perception of vibration at 31.5 and 125 Hz) and finger systolic blood pressures were measured in 107 dockyard workers, including 31 controls and 76 workers exposed to hand-transmitted vibration (50 reporting finger blanching consistent with vibration-induced white finger). A history of vibration exposure and symptoms associated with hand-transmitted vibration were obtained for each subject. RESULTS: Increased duration of exposure to vibration resulted in a deterioration of both thermal thresholds and vibrotactile thresholds. Finger systolic blood pressures were lower in subjects reporting finger blanching and were related to the extent of blanching on the measured finger. Reported sensations of tingling were not correlated with any of the threshold measures; thermal thresholds and vibrotactile thresholds showed evidence of deterioration with reports of increasing numbness. Both numbness and tingling were correlated with reports of finger blanching. Finger systolic blood pressures were not correlated with either thermal or vibrotactile thresholds. CONCLUSIONS: Vascular and neurological signs produced by hand-transmitted vibration can occur independently, but the principal vascular symptom (i.e. attacks of blanching) and some commonly reported neurological symptoms (i.e. sensations of numbness and tingling) may be related.

Adult↗
PubMed1999

Assessment of autonomic nervous activity in hand-arm vibration syndrome patients using time- and frequency-domain analyses of heart rate variation.

OBJECTIVES: The aim of the present study was to non-invasively assess autonomic nervous activity, using time- and frequency-domain analyses of heart rate variation (HRV), and to investigate the relationship between indices of HRV and duration of exposure to vibration (DEV), time since retirement from work involving vibration (TR) and time undergoing treatment (TT) in a group of patients with hand-arm vibration syndrome (HAVS). SUBJECTS AND METHODS: Twenty one HAVS patients who were no longer exposed to vibration and were undergoing standard treatment for HAVS, and 10 healthy control subjects, similar to the patients in age, height, weight and number of current smokers and drinkers, volunteered for this study. Indices of HRV [time-domain indices (the mean of R-R intervals, standard deviation and coefficient of variation) and normalized units of frequency-domain indices [low frequency (LF) and high frequency (HF) components], indicating parasympathetic nervous activity, were calculated from 2 min electrocardiographic data recorded during spontaneous breathing by subjects in supine rest. RESULTS: The LF and HF components of the patients were significantly lower than those of the healthy controls (P < 0.05). When Pearson correlation analysis was applied for the patient group, using indices of HRV with age, weight, height, DEV, TR and TT, the LF components positively related to TR and TT (P < 0.01). The patients were thus divided into three groups as follows, according to TR: group A (</=1 year), group B (>1 to <5 years) and group C (>/=5 to </=10 years), or according to TT: group X (</=1 year), group Y (>1 to <5 years) and group Z (>/=5 to </=10 years). The LF components of the groups A and X were significantly lower than that of the healthy controls (P < 0.01). The HF components of the groups A and X were also significantly lower than that of the healthy controls (P < 0.05). CONCLUSIONS: The findings of the present study indicate decreased cardiac parasympathetic activity in the HAVS patients in comparison to the healthy controls. The TT and TR significantly influenced the HRV results in these patients; however, the DEV did not. The findings also indicate that treatment and cessation of exposure to vibration might have a beneficial effect on the cardiac parasympathetic activity in HAVS patients.

Aged↗
PubMed1999

Medial plantar nerve conduction velocities among patients with vibration syndrome due to chain-saw work.

OBJECTIVE: The present study examined the effect of the vibration syndrome (VS) on the peripheral nervous system in the lower extremities. METHODS: Thirty-eight patients with VS due to previous exposure to vibration from chain-saw work and 55 age-matched controls were examined for sensory nerve conduction velocities in the medial plantar nerve (SCV-P). The patient group was divided into two subgroups, one with (n=19) and the other without vibration-induced white finger (VWF; n=19). RESULTS: Analysis of variance of SCV-P for the three groups showed significant difference (F(2,89)=10.65, P < 0.0001). A significant difference was found between the controls and the VWF(+) group (P < 0.0001) but not between the controls and the VWF(-) group (P=0.0508) by multiple comparison using Scheffe's method. CONCLUSION: These findings suggest that VS affects the peripheral nervous system function in the lower extremities via mediation of circulatory disturbance manifested as VWF.

Action Potentials↗
PubMed2003

Dynamic force responses of skeletal muscle during stretch-shortening cycles.

Muscle damage due to stretch-shortening cycles (i.e., cyclic eccentric/concentric muscle actions) is one of the major concerns in sports and occupational related activities. Mechanical responses of whole muscle have been associated with damage in neural motor units, in connective tissues, and the force generation mechanism. The objective of this study was to introduce a new method to quantify the real-time changes in skeletal muscle forces of rats during injurious stretch-shortening cycles. Male Sprague Dawley rats ( n=24) were selected for use in this study. The dorsi flexor muscle group was exposed to either 150 stretch-shortening cycles ( n=12) or 15 isometric contractions ( n=12) in vivo using a dynamometer and electrical stimulation. Muscle damage after exposure to stretch-shortening cycles was verified by the non-recoverable force deficit at 48 h and the presence of myofiber necrosis. Variations of the dynamic forces during stretch-shortening cycles were analyzed by decomposing the dynamic force signature into peak force ( F(peak)), minimum force ( F(min)), average force ( F(mean)), and cyclic force ( F(a)). After the 15th set of stretch-shortening cycles, the decrease in the stretch-shortening parameters, F(peak), F(min), F(mean), and F(a), was 50% ( P<0.0001), 26% ( P=0.0055), 68% ( P<0.0001), and 50% ( P<0.0001), respectively. Our results showed that both isometric contractions and stretch-shortening cycles induce a reduction in the isometric force. However, the force reduction induced by isometric contractions fully recovered after a break of 48 h while that induced by stretch-shortening cycles did not. Histopathologic assessment of the tibialis anterior exposed to stretch-shortening cycles showed significant myofiber degeneration and necrosis with associated inflammation, while muscles exposed to isometric contractions showed no myofiber degeneration and necrosis, and limited inflammation. Our results suggest that muscle damage can be identified by the non-recoverable isometric force decrement and also by the variations in the dynamic force signature during stretch-shortening cycles.

Animals↗
PubMed2003

New aspects of the hormone and cytokine response to training.

Exercise training is associated with peripheral-cellular and central-cerebral processes, hormonal-neuronal regulation and transmission mechanisms. During the acute training response, peripheral cellular mechanisms are mainly metabolostatic to achieve energy supply and involve associated cytokine and hormonal reactions. Glycogen deficiency is associated with increased expression of local cytokines (interleukin-6, IL-6), decreased expression of glucose transporters, increased cortisol and decreased insulin secretion and beta-adrenergic stimulation. A nutrient-sensing signal of adipose tissue may be represented by leptin which, as for insulin, IL-6 and insulin-like growth-factor I (IGF-I), has profound effects on the hypothalamus and is involved in the metabolic hormonal regulation of exercise and training. Muscle damage and repair processes may involve the expression of inflammatory cytokines (e.g. tumour necrosis factor-alpha, TNF-alpha) and of stress proteins (e.g. heat shock protein 72). During overreaching and overtraining, a myopathy-like state is observed in skeletal muscle with depressed turnover of contractile proteins (e.g. in fast-type glycolytic fibres with a concomitant increase in slow type myosins). These alterations are influenced by exercise-induced hypercortisolism, and by decreased somatotropic hormones (e.g. IGF-I). The hypothalamus integrates various error signals (metabolic, hormonal, sensory afferents and central stimuli) and therefore pituitary releasing hormones represent the functional status of an athlete and long-term hypothalamic hormonal and sympathoadrenal downregulation are some of the prominent hormonal signs of prolonged overtraining and performance incompetence syndrome.

Adaptation, Physiological↗
PubMed2004

The effect of a repeat bout of exercise on muscle injury in persons with spinal cord injury.

Following an initial bout of damaging exercise, a successive bout of similar exercise typically results in less injury, known as the "protective effect". Unloading due to spinal cord injury (SCI) increases the susceptibility to contraction-induced muscle injury. We tested the hypothesis that two bouts of isometric actions would evoke the same damage in the quadriceps femoris (QF) of patients with SCI. Six male subjects [32 (5) years old, 182 (9) cm, 81 (21) kg, injury level C6-T7, 6 (2) years post-injury, mean (SD)] were tested at two time points (Time1, Time2), separated by 8 weeks. Magnetic resonance images were taken of the QF prior to, immediately after, and 3 days after electromyostimulation (EMS) that evoked isometric knee extension. EMS (50 Hz) consisted of five sets of ten contractions (2 s on/6 s off, 1 min b/t sets) followed by three sets of ten contractions (1 s on/1 s off, 30 s b/t sets). Relative cross-sectional area of stimulated and injured skeletal muscle was obtained by quantifying pixels with an elevated T2. Relative area of stimulated QF was the same for both time points [92 (6)% and 89 (7)%] as was torque loss (approximately 55%). Three days post-EMS, the relative area of stimulated QF injured was not different between time points [30 (14)% vs 29 (17)%, P>0.05]. These results indicate an absence of a protective effective for repeat exercise bouts separated by 8 weeks in SCI patients using EMS.

Adult↗
PubMed2004

MRI evaluation of topical heat and static stretching as therapeutic modalities for the treatment of eccentric exercise-induced muscle damage.

The aim of this study was to monitor the effects of topical heat and/or static stretch treatments on the recovery of muscle damage by eccentric exercise. For this purpose, 32 untrained male subjects performed intense eccentric knee extension exercise, followed by 2 weeks of treatment (heat, stretch, heat plus stretch) or no treatment (control, n=8/group). Isometric strength testing, pain ratings, and multi-echo magnetic resonance imaging of the thigh were performed before and at 2, 3, 4, 8, and 15 days following the exercise. Increased T2 relaxation time, muscle swelling, pain ratings, and strength loss confirmed significant muscle damage during the post-exercise period. Pain ratings and muscle volume recovered to baseline by 15 days, although muscle strength remained lower [77 (4) vs. 95 (3) kg pre-exercise, mean (SE)] and T2 values higher [32.2 (0.8) vs. 28.6 (0.2) ms pre-exercise]. Our results indicate that heat and/or static stretching does not consistently reduce soreness, swelling or muscle damage. The practical implication of our findings is that clinicians should be aware that prescribing heat and/or static stretching following intense eccentric or unaccustomed exercise will not enhance the recovery of damaged muscles.

Adult↗
PubMed2005

Pure eccentric exercise does not activate blood coagulation.

Eccentric exercise can cause skeletal muscle damage with ultrastructural disruption, inflammation and increased proteolytic enzyme activity. It may be possible that these changes are able to trigger blood coagulation in vivo. The aim of the study was to investigate changes in blood coagulation via the measurement of aPTT, the thrombin potential (total [TTP] and endogenous [ETP], both intrinsic [in] and extrinsic [ex]) and the thrombin generation (prothrombinfragment 1 + 2 [F1 + 2] and thrombin-antithrombin complex [TAT]) after pure eccentric exercise. Seventeen healthy non-smokers (28 +/- 6 years, VO2-peak 59 +/- 7 ml/min/kg) underwent pure eccentric down jumps (9 x 28 isolated down jumps in 90 min, drop from a height of 55 cm), a cycle exercise (90% of the individual anaerobic threshold for 60-90 min) and a control experiment on different days. Blood samples were drawn after a 30-min rest, immediately, and 2 h after exercise. After the cycle exercise, a clear shortening by 12% (P<0.001) in aPTT and an increase in TTPin (13%; P<0.05) and TAT (33%; P<0.05) in comparison to the control experiment were seen, while after eccentric exercise only minimal changes in aPTT and thrombin potential (TTPin, ETPin) and no thrombin generation (F1 + 2 and TAT) were found. In contrast to concentric dynamic exercise, e.g. cycle ergometry, only insignificant changes in thrombin potential and no thrombin generation could be observed after skeletal muscle damage induced by pure eccentric exercise. It can be concluded that the mechanical impact associated with eccentric exercise does not activate blood coagulation.

Adult↗
PubMed2005

The effects of exercise-induced muscle damage on maximal intensity intermittent exercise performance.

Exercise-induced muscle damage (EIMD) is a common occurrence following activities with a high eccentric component. Alterations to the torque-velocity relationship following EIMD would appear to have serious implications for athletic performance, particularly as they relate to impairment of maximal intensity exercise. However, this has been studied infrequently. The purpose of this study was to assess the effects of EIMD on maximal intermittent sprint performance. Ten male participants (age 22.4 +/- 3.2 years, height 178.6 +/- 5.2 cm, mass 80.6 +/- 10.7 kg) performed 10 x 6 s cycle ergometer sprints, interspersed with 24 s recovery against a load corresponding to 0.10 kp/kg and 10 x 10 m sprints from a standing start, each with 12 s active (walking) recovery. All variables were measured immediately before and at 30 min, 24, 48 and 72 h following a plyometric exercise protocol comprising of 10 x 10 maximal counter movement jumps. Repeated measures ANOVA showed significant changes over time (all P<0.05) for perceived soreness, plasma creatine kinase activity (CK), peak power output (PPO), sprint time and rate of fatigue. Soreness was significantly higher (P<0.01) than baseline values at all time intervals (3.1, 4.9, 5.5 and 3.2 at 30 min, 24, 48 and 72 h, respectively). CK was significantly elevated (P<0.05) at 24 h (239 IU/l) and 48 h (245 IU/l) compared to baseline (151 IU/l). PPO was significantly lower (P<0.05) than baseline (1,054 W) at all time intervals (888, 946, 852 and 895 W, at 30 min, 24, 48 and 72 h, respectively). The rate of fatigue over the ten cycling sprints was reduced compared to baseline, with the greatest reduction of 48% occurring at 48 h (P<0.01). This was largely attributed to the lower PPO in the initial repetitions, resulting in a lower starting point for the rate of fatigue. Values returned to normal at 72 h. Sprint times over 10 m were higher (P<0.05) at 30 min, 24 h and 48 h compared to baseline (1.96 s) with values corresponding to 2.01, 2.02 and 2.01 at 30 min, 24 h and 48 h, respectively. Values returned to baseline by 72 h. The results provide further evidence that, following a plyometric, muscle-damaging exercise protocol, the ability of the muscle to generate power is reduced for at least 3 days. This is also manifested by a small, but statistically significant reduction in very short-term (approximately 2 s) intermittent sprint running performance. These findings have implications for appropriate training strategies in multiple sprint sports.

Adaptation, Physiological↗
PubMed2005

Reliability of maximal muscle force and voluntary activation as markers of exercise-induced muscle damage.

The loss of the ability of skeletal muscle to generate force is one of the most appropriate and valid means to quantify muscle damage. Routine measurements of maximal muscle force, however, include many potential sources of error, the most important of which may be a possible lack of central drive to the muscles. The aim of the present study was to determine the reliability of maximal isometric quadriceps muscle force and voluntary activation over a time scale that is typically employed to examine the aetiology of exercise-induced muscle damage. We also attempted to characterise the reliability of several twitch interpolation variables including the size of the interpolated twitch and the state (i.e. un-potentiated vs potentiated) and size of the resting twitch. Over a 7-day period, eight healthy active males performed repeated maximal voluntary isometric contractions (MVC) of the quadriceps (baseline and 2 h, 6 h, 24 h, 48 h, 72 h and 7 days post). Systematic variations in maximal muscle force, voluntary activation, interpolated twitch, un-potentiated twitch and potentiated twitch were not statistically significant (P>0.05) and 95% repeatability coefficients of +/-76.03 N, +/-4.42%, +/- 8.44 N, +/-25.92 N and +/-43.58 N were observed, respectively. These data indicate that young healthy well-familiarized male subjects can reproduce their perceived maximal efforts both within and between days where activation levels of >90% are routinely achieved. Providing activation remains within these limits in the 7 days following an acute bout of exercise, the researcher would be 95% certain that exercise-induced muscle damage is present in individual subjects (taken from similar subject populations) if MVC force falls outside these limits.

Adult↗
PubMed2006

Using myoelectric signal parameters to distinguish between computer workers with and without trapezius myalgia.

Complaints of chronic trapezius muscle pain among computer workers have increased in prevalence during the last decade. Currently there is no clear understanding of the pathophysiological mechanisms involved in affected muscles. The major objective of this work was to determine if measurable electrophysiological differences exist between the trapezius muscles in individuals suffering from trapezius myalgia (TM) and occupation-matched pain-free control subjects. Myoelectric signal (MES) data were recorded from the upper trapezius muscle while subjects with and without myalgia performed a standardized series of postural and arm-holding tasks. MES variables reflecting muscle fatigue, muscle tension and motor control strategies were analyzed to determine their potential ability to distinguish between the two groups. One variable, RestTime, was found to be significantly different between the groups but it was not specific enough to predict group association. A multivariate logistic regression analysis yielded a model that separated the two groups with better than 70% sensitivity and 70% specificity. The variables included in the model reflect differences in trapezius muscle activity between the groups, particularly related to motor control and/or active muscle tension, but not fatigue. The model was tested using a small sample of new data, which again produced a good sensitivity (85.7%) but not specificity (42.9%). To the authors' knowledge, this is the first objective MES-based model that has successfully classified subjects with or without TM based on a simple clinical test. Further work with this model might result in understanding the pathophysiology of TM, assisting with clinical diagnosis, and testing the effect of various treatment interventions.

Adult↗
PubMed2007

Monitoring for overreaching in rugby league players.

The aim of this study was to identify indicators of non-functional overreaching (NFOR) in team sport athletes undertaking intensive training loads. Eighteen semi-professional rugby league players were randomly assigned into two pair matched groups. One group completed 6 weeks of normal training (NT) whilst the other group was deliberately overreached through intensified training (IT). Both groups then completed the same 7-day stepwise training load reduction taper. Multistage fitness test (MSFT) performance, VO2 (max), peak aerobic running velocity (V (max)), maximal heart rate, vertical jump, 10-s cycle sprint performance and body mass were measured pre- and post-training period and following the taper. Hormonal, haematological and immunological parameters were also measured pre-training and following weeks 2, 4 and 6 of training and post-taper. MANOVA for repeated measures with contrast analysis indicated that MSFT performance and VO2 (max) were significantly reduced in the IT group over time and condition, indicating that a state of overreaching was attained. However, the only biochemical measure that was significantly different between the IT and NT group was the glutamine to glutamate (Gln/Glu) ratio even though testosterone, testosterone to cortisol (T/C) ratio, plasma glutamate, and CK activity were significantly changed after training in both groups. Positive endurance and power performance changes were observed post-taper in the IT group confirming NFOR. These changes were associated with increases in the T/C ratio and the Gln/Glu ratio and decreases in plasma glutamate and CK activity. These results indicate that although there was no single reliable biochemical marker of NFOR in these athletes, the Gln/Glu ratio and MSFT test may be useful measures for monitoring responses to IT in team sport athletes.

Adult↗
PubMed2000

Trapezius muscle activity, neck and shoulder pain, and subjective experiences during monotonous work in women.

The electromyographic (EMG) activity patterns of 18 female supermarket employees reporting neck and shoulder pain were compared with those of 6 of their female colleagues reporting no pain when doing cash-register work. It was found that the EMG activity of the trapezius muscle tended to show a lack of low and high levels among pain subjects, and that the time the trapezius muscle was at rest was longer in the group reporting no pain. In the non-dominant side, the muscle rest time was significantly longer (P < 0.05) in the group reporting no pain, and this group also showed a larger EMG activity difference between the dominant and non-dominant sides, indicating a less static bilateral muscle activation. Self-reports of negative experiences (stressed, exhausted and tense) were somewhat higher in the group reporting pain, while positive experiences during work (concentrated, stimulated and happy) appeared to be similar in the two groups of supermarket employees.

Adult↗