摘要:

MAFFULLI, N., S. W. WATERSTON, and S. W. B. EWEN. Ruptured Achilles tendons show increased lectin stainability.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1057–1064, 2002.PurposeTo ascertain whether lectins could be a useful tool for investigation of the extracellular matrix of degenerated and normal tendons.MethodsHematoxylin-eosin–stained slides were assessed blindly using a semiquantitative grading scale for fiber structure, fiber arrangement, rounding of the nuclei, regional variations in cellularity, increased vascularity, decreased collagen stainability, hyalinization, and glycosaminoglycan, with a pathology score giving up to three marks per each of the above variables, with 0 being normal and 3 being maximally abnormal. For lectin staining withAleuria aurantia,Canavalia ensiformis,Galanthus nivalis,Phaseolus vulgaris,Arachis hypogea,Sambucus nigra, andTriticum vulgaris, assessment of staining on a scale from 0 (no staining) to 5 (strong staining) was performed blindly.ResultsThe mean pathology sum score of ruptured tendons (N= 14; average age 46.5 yr, range 29–61) was significantly greater than the mean pathology score of the control tendons of Achilles tendons from individuals with no known tendon pathology (N= 16; average age 62.5 yr, range 49–73) (pathology score: 18.5 ± 3.2 vs 6.1 ± 2.3). Four of the seven lectins used exhibited significantly positive results.ConclusionsRuptured tendons were histologically significantly more degenerated than control tendons. Ruptured tendons showed different lectin staining properties than nonruptured ones. This difference may have resulted from posttranslational changes in the extracellular matrix producing alterations in the biochemistry of the tendon, which might interfere with the interaction with the lateral sugar residues of the collagen molecules or cause steric blockade.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

MEYER, H. E., A. J. SØGAARD, A. TVERDAL, and R. M. SELMER. Body mass index and mortality: the influence of physical activity and smoking.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1065–1070, 2002.PurposeTo study the association between body mass index (BMI) and mortality, and to evaluate the effect of physical activity during leisure time and smoking on this association in a general male population.MethodsDuring 1974–1978, all men aged 35–49 yr living in three Norwegian counties were invited to a cardiovascular screening, and 87.1% attended and had their weight and height measured. Men with recognized cardiovascular diseases, diabetes mellitus, or cancer at screening were excluded. The cohort (N= 22,304) was followed for an average of 16.3 yr with respect to total and cause-specific mortality.ResultsDuring follow-up, 1909 men died. We found a J-shaped association between BMI and total mortality, and the form of association was similar for death from cardiovascular diseases. Although not statistically significant, a J-shaped association was also suggested in never-smokers. Irrespective of BMI level, ex- and never-smokers had lower mortality than current smokers. Obese smoking men had a relative risk of dying of 2.01 (95% CI: 1.29–3.11) compared with obese never-smokers, and a relative risk of 4.55 (95% CI: 3.34–6.20) compared with normal weight never-smokers (BMI 22–24.9 kg·m−2). Within each category of physical activity during leisure time, obese men had a similar increased relative risk of death compared with normal-weight individuals. However, the U- to J-shaped association between BMI and mortality seemed to disappear by increasing level of physical activity, but this finding was not significant.ConclusionThis study suggests a J-shaped association between BMI and total mortality, also when stratified on smoking habits and physical activity. The suggested linear trend in the most physical active men needs to be reassessed.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

SWAIN, D. P., and B. A. FRANKLIN. Is there a threshold intensity for aerobic training in cardiac patients?Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1071–1075, 2002.PurposeRecent guidelines have recommended the use of a percentage of oxygen uptake reserve (&OV0312;O2R) for prescribing aerobic exercise intensity for cardiac patients. Moreover, these guidelines suggest that a threshold intensity may exist, below which no improvement in peak oxygen uptake (&OV0312;O2peak) occurs. The purpose, therefore, was to translate the intensity of aerobic exercise in previous training studies using cardiac patients into %&OV0312;O2R units, and determine whether a threshold intensity exists.MethodsTwenty-three studies, using 28 groups of aerobically trained cardiac patients, were identified in which &OV0312;O2peakwas measured before and after training by gas exchange. Intensity of exercise was variously described as a percentage of &OV0312;O2peak, percentage of peak heart rate (HRpeak), percentage of heart rate reserve (HRR), or percentage of peak workload. These intensities were translated into equivalent units of %&OV0312;O2R.ResultsOf the 28 groups of patients, three failed to show significant improvements in &OV0312;O2peak. These groups exercised at intensities corresponding to 47–55% of &OV0312;O2R. However, six other groups exercised at comparable intensities (i.e., 42% to 55% of &OV0312;O2R) and experienced significant increases in &OV0312;O2peak. Other confounding variables in these studies were similar, including the initial &OV0312;O2peakof the subjects, suggesting that the failure of three groups to significantly improve aerobic capacity was due to their small sample size.ConclusionNo threshold intensity for aerobic training was identified in cardiac patients, with the lowest intensity studied being approximately 45% of &OV0312;O2R. It is possible that intensities below this value may be an effective training stimulus, especially in extremely deconditioned subjects, but further research is needed to test that possibility and to determine whether a threshold exists.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

GREEN, J. P., S. G. GRENIER, and S. M. MCGILL. Low-back stiffness is altered with warm-up and bench rest: implications for athletes.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1076–1081, 2002.IntroductionGeneral practice in many team sports is to have the athletes who do not start in a game sit on a bench while waiting to play. The purpose of this study was to examine the effect of a warm-up followed by bench rest on the stiffness of the lumbar spine in athletes.MethodsNine varsity-level volleyball players volunteered to have their lumbar-spine stiffness measured. The protocol consisted of an initial stiffness measurement followed by a 30-min warm-up, then another stiffness measurement, then 30 min of bench rest, and finally a third stiffness measurement.ResultsIn general, lumbar spine stiffness increased as a result of bench rest after a warm-up. This effect was seen in both the spine extension and lateral bend axes but not in the flexion or axial twist axes. However, there was no decrease in stiffness associated with the active warm-up portion of the task.ConclusionsIt was concluded that a warm-up followed by bench rest does lead to an increase in stiffness of the lumbar spine, suggesting this practice is not in the best interest of reducing the risk of back injury or optimal performance.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

NG, J. K.-F., V. KIPPERS, M. PARNIANPOUR, and C. A. RICHARDSON. EMG activity normalization for trunk muscles in subjects with and without back pain.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1082–1086, 2002.PurposeThe aims of the present study were to examine electromyographic (EMG) activity of six bilateral trunk muscles during maximal contraction in three cardinal planes and to determine the direction of contraction that gives maximal activation for each muscle, both for healthy subjects and back-pain patients.MethodsTwenty-eight healthy subjects and 15 back-pain patients performed maximum voluntary contractions in three cardinal planes. Surface EMG signals were recorded from rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum, and multifidus bilaterally. Root mean square values of the EMG data were calculated to quantify the amplitude of EMG signals.ResultsFor both healthy subjects and back-pain patients, one single direction of contraction was found to give the maximum EMG signals for most muscles. Rectus abdominis demonstrated maximal activity in trunk flexion, external oblique in lateral flexion, internal oblique in axial rotation, and multifidus in extension. For the latissimus dorsi and iliocostalis lumborum, maximal activity was demonstrated in more than one cardinal plane.ConclusionThis study has implications for future research involving normalization of muscle activity to maximal levels required in many trunk EMG studies. As the latissimus dorsi and iliocostalis lumborum demonstrate individual differences in the plane that gives maximal activity, these muscles may require testing in more than one plane.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

BROWN, D. R. and C. J. BLANTON. Physical activity, sports participation, and suicidal behavior among college students.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1087–1096, 2002.PurposeTo evaluate the relationship between physical activity, sports participation, and suicidal behavior among college students (N= 4,728).MethodsData from the 1995 National College Health Risk Behavior Survey were analyzed. Students were classified as engaging in frequent vigorous activity 6–7 d·wk−1, vigorous activity 3–5 d·wk−1, moderate activity, low activity, or no activity. Sports participation was dichotomized into “yes” or “no” participation. Suicidal behavior was defined as thoughts about, plans for, or attempts at suicide during the 12 months before completing the survey. Data were stratified by sex and multivariable logistic regression modeling, calculated odds ratios (ORs) (adjusted for age, race/ethnicity, Body Mass Index/weight perception, cigarette smoking, episodic heavy alcohol use, drug use, and either activity level or sport participation) for suicidal behavior as associated with physical activity and sports participation.ResultsAdjusted ORs show that men in the “low activity” group were at almost half the odds (adjusted OR = 0.54;P< 0.015) of reporting suicidal behavior than men in the “not active” group. Women who engaged in moderate or frequent vigorous activity were at greater odds of reporting suicidal behavior compared with inactive women; OR = 1.76 (P< 0.035) and 1.99 (P< 0.034) respectively. Sports participation was protective against suicidal behavior. Adjusted ORs show that men who did not participate in sports were 2.5 times (P< 0.0003) more likely to report suicidal behavior than men who were sports participants. Women not participating in sports had 1.67 times the odds of reporting suicidal behavior than women sports participants (P< 0.05).ConclusionsAssociations were found between sports participation/selected patterns of physical activity and suicidal behavior. Causal factors mediating the relationships need to be identified.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

JACKSON, E. M., and R. K. DISHMAN. Hemodynamic responses to stress among black women: fitness and parental hypertension.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1097–1104, 2002.PurposeWe compared hemodynamic aspects of the relationship between cardiorespiratory fitness and blood pressure changes during and after laboratory stress in young black women with or without parental history of hypertension.MethodsParticipants were 30 normotensive, black American women having low to moderate fitness levels (i.e., &OV0312;O2peak) assessed by cycle ergometry who performed standard active and passive coping laboratory stressors. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance (TPR), calf blood flow (CBF), and calf vascular resistance (CVR) were assessed during exposure to forehead and hand cold pressors, and mental arithmetic, as well as during recovery after the tasks.ResultsFitness was positively related to increases in either TPR or CVR during each stressor. In contrast, fitness was positively related to blunted blood pressure during or after passive stress (i.e., hand or forehead cold) and enhanced recovery of blood pressure and TPR after the active stressor (i.e., mental arithmetic); effects of fitness on the vascular responses during and after mental arithmetic were stronger among women having a negative history of parental hypertension.ConclusionThe findings confirm our previous report that fitness blunts systolic blood pressure response during the hand cold pressor in young women. They also suggest that future studies of fitness and blood pressure reactivity during stress should focus on the regulation of vascular responses and their recovery after stress. Weaker effects of &OV0312;O2peakafter mental arithmetic in the positive history group indicate that the level of fitness required to modify recovery from mental stress among black American women may differ according to parental history of hypertension.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

FIEBIG, R. G., J. M. HOLLANDER, D. NEY, R. BOILEAU, E. JEFFERY, and L. L. JI. Training down-regulates fatty acid synthase and body fat in obese Zucker rats.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1106–1114, 2002.IntroductionThe purpose of this study was to investigate whether chronic exercise training attenuates fatty acid synthase, the rate-limiting enzyme for hepatic lipogenesis, and the accumulation of body fat by using obese Zucker rats (OZR) as a model.MethodsFemale obese Zucker (fa/fa) rats (O,N= 16) and their lean litter mates (L,N= 16) were randomly divided into a trained (T) and untrained (U) group. T was performed on a treadmill for 2 h·d−1, 5 d·wk−1, 10 wk with running speed and grade adjusted to elicit similar workloads. All rats were meal-fed a high-cornstarch diet for 4 h·d−1and killed 8 h after the initiation of the last meal and 27 h after the last T session, in the resting state.ResultsO rats exhibited twofold higher FAS activity and sixfold higher FAS mRNA abundance in the liver than L rats (P< 0.05), accompanied by a severe hyperinsulinemia (P< 0.05) but normal glucagon and glucose levels. FAS activity, but not mRNA level, was decreased by 18% with T in O rats (P< 0.05). T decreased percent body fat in both O and L rats (P< 0.05), and increased lean body mass in O rats (P< 0.05). Hepatic fatty acid profile showed higher 16:0, 16:1, and 18:1 concentrations in O rats, whereas 18:0, 18:2, and 20:4 were lower (P< 0.05). Training increased 20:4 in both O and L rats (P< 0.08). Nuclear protein binding to the insulin response sequence (IRS/A) and carbohydrate response element (ChoRE) on FAS gene promoter was decreased, whereas inverted CAATT box element (ICE) binding was increased in O versus L rats (P< 0.05). Training did not affect the binding of these gene sequences.ConclusionDe novolipogenesis was greatly enhanced in OZR. Endurance training decreased body fat, which is partly explained by a decreased FAS activity. However, FAS down-regulation was not due to altered nuclear protein binding to FAS gene.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

LINDERMAN, J. K., and E. R. BLOUGH. Aging does not attenuate plantaris muscle hypertrophy in male Fischer 344 rats.Med. Sci. Sports Exerc., Vol. 34, No. 7, pp. 1115–1119, 2002.PurposeThe present study examined the effect of extreme old age on the plasticity of the rat plantaris muscle in response to an increase in mechanical load.MethodsMale Fischer 344 rats, aged 7 months (adult) and 25 months (old) underwent bilateral surgical ablation of the gastrocnemius muscle to functionally overload (OV) the fast-twitch plantaris muscle for 8 wkResultsAt 27 months of age, plantaris wet weight and cross-sectional area (CSA) were unaffected by age, but aging decreased peak isometric tension (Po) 27% (P< 0.05). Plantaris muscle myosin heavy chain composition indicated a loss of faster myosin heavy chains (MHC) isoforms with concomitant increases in slower MHC in old rats (P< 0.05). In adult rats, OV increased muscle CSA and Po 72% and 83%, respectively (P< 0.05). Similarly, OV increased CSA and Po 69% and 73%, respectively, in old rats (P< 0.05). Average fiber CSA increased 57% and 68% in adult-OV and old-OV rats, respectively (P< 0.05).ConclusionCollectively, our data indicate that plantaris muscle mass and plasticity in response to increased mechanical load are well conserved in very aged male Fischer 344 rats.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID