Exercise,physical activity,and exertion over the business cycle

Shifts in time and income constraints over economic expansions and contractions would be expected to affect individuals' behaviors. We explore the impact of the business cycle on individuals' exercise, time use, and total physical exertion, utilizing information on 112,000 individual records from the 2003–2010 American Time Use Surveys. In doing so, we test a key causal link that has been hypothesized in the relation between unemployment and health, but not heretofore assessed. Using more precise measures of exercise (and other activities) than previous studies, we find that as work-time decreases during a recession, recreational exercise, TV-watching, sleeping, childcare, and housework increase. This, however, does not compensate for the decrease in work-related exertion due to job-loss, and total physical exertion declines. These effects are strongest among low-educated men, which is validating given that employment in the Great Recession has declined most within manufacturing, mining, and construction. We also find evidence of intra-household spillover effects, wherein individuals respond to shifts in spousal employment conditional on their own labor supply. The decrease in total physical activity during recessions is especially problematic for vulnerable populations concentrated in boom-and-bust industries, and may have longer-term effects on obesity and related health outcomes.     

Wrongful Life Cases and The Courts

No abstract available for this article.     

Benefits of Swimming in Asthma: Effect of a Session of Swimming Lessons on Symptoms and PFTs with Review of the Literature

A study involving eight children with moderate persistent asthma was undertaken to determine whether standard swimming lessons improved symptoms and pulmonary function tests (PFTs) in asthmatic children. Five children ages 7–12 years old with moderate persistent asthma were randomized to a swimming lesson group (5- to 6-week session) and three to a control group. Both groups completed pre- and poststudy period PFTs and symptom questionnaires. Swimming lessons did not produce a significant change in asthma symptoms or PFTs. Review of previous literature found that swimming has been shown to have definite benefits in improving cardiorespiratory fitness in asthmatic children. Swimming has been shown to be less asthmogenic than other forms of exercise. Some studies have also shown improvement in asthma symptoms in children participating in exercise programs.     

Evaluation of plasma retinol-binding protein as a surrogate measure for plasma retinol concentrations

Fasting growth hormone (GH) levels and GH responses to exercise were studied in normally menstruating women and in women taking oral contraceptives in order to find out whether the GH levels were related to the menstrual cycle or changed by oral contraceptives. The GH response to exercise was found to be higher when exercise was done in the midcycle period than when it was done at other points of time during the normal menstrual cycle. Fasting GH levels were unchanged throughout the menstrual cycle. Fasting GH levels and GH responses to exercise performed outside the midcycle period were identical in normally menstruating women and in women taking oral contraceptives. In conclusion, the GH response to exercise, but not fasting GH levels, were related to the menstrual cycle. The estrogen and progestin components of the contraceptives used in this study were balanced in such a way that the growth hormone levels and growth hormone responses to exercise were not changed by long-term therapy with these drugs.     

Exhaustive exercise increases plasma/serum total oxidation resistance in moderately trained men and women,whereas their VLDL+ LDL lipoprotein fraction is more susceptible to oxidation

The purpose of this study was to evaluate the effects of exhaustive exercise (marathon run) on different lipid peroxidation measurements, including copper-induced serum lipids and VLDL+ LDL oxidation susceptibility, and on plasma total antioxidative capacity (TRAP), muscular damage and plasma antioxidants in healthy moderately trained male (n= 21) and female (n= 25) volunteers. Blood samples were taken before and just after the 42-km run. In women, baseline levels of several antioxidative compounds (serum albumin and uric acid, plasma free thiols and blood glutathione) were lower, resulting in 21.5% lower plasma total antioxidative capacity and 70.3% higher serum oxidation susceptibility, compared to men. To compare effects in men and women, the exercise-induced variable changes were adjusted for their baseline levels. After this adjustment, there were no statistically significant differences between the genders in the extent of muscular damage (serum creatine kinase, (CK)), or in the change in serum lipids or VLDL+ LDL oxidation susceptibility, or that of plasma antioxidative capacity. A possible beneficial effect of exercise was that serum HDL cholesterol levels increased significantly in both genders, but especially in women. In the group of pooled genders (n= 46), the increases in serum CK and in plasma lactate were 190% (95% CI, 133% to 246%) and 109% (95% CI, 65% to 175%), respectively. On the basis of our lipid peroxidation and TRAP measurements, uric acid was observed to be the most important plasma antioxidant. The effect of exercise was to decrease the oxidation susceptibility of serum lipids by 24.8% (95% CI 13.4% to 36.2%) and to elevate plasma TRAP by 14.6% (95% CI, 11.4% to 17.7%). Nonetheless, the oxidation susceptibility of the VLDL+ LDL fraction increased by 11.0% (95% CI, 1.9% to 20.2%). Our results suggest that there are no gender-based differences in exhaustive exercise-induced lipid peroxidation or muscular damage. Secondly, even though exhaustive exercise can increase plasma/serum total resistance towards oxidation, the oxidation resistance of the atherogenic lipoprotein fraction might be diminished. On the basis of these results, several in vitro measurements of lipid peroxidation assessing both water and lipid soluble plasma fractions are needed if a true perspective of the plasma redox status is to be obtained.     

The Effects of 10 Weeks Military Training on Heel Ultrasound and Bone Turnover

To measure the physiological changes in bone in response to strenuous exercise we performed a prospective study of male army recruits over 10 weeks of basic training. Measurements performed at the start and completion of training consisted of ultrasound (US) measurements of the heel: velocity of sound (VOS in m/seconds) and broadband ultrasound attenuation (BUA in dB/MHz) and bone turnover markers; osteocalcin (OC), bone-specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase (TRAP). Forty subjects were recruited for the study and 26 completed training. Over the 10-week study period there was a significant 1.7% fall in mean VOS [mean paired difference (mpd) 27.2 m/second, SEM 9.5 (95% CI 7.5–46.8) P= 0.009] and a nonsignificant 3.4% increase in BUA (P= 0.159). There were significant falls in markers of bone formation OC [11.6%, mpd 0.11 μg/liter (95% CI 0.07–0.14) P < 0.001] and BALP [13.3%, mpd 3.49 U/liter (CI 0.80–6.18) P= 0.013] and a nonsignificant 9.5% fall in TRAP a marker of bone resorption. The 10 recruits subsequently injured had a significantly lower VOS on entry [mean difference 24.2 m/seconds (95% CI 4.6–43.7) P= 0.017] and nonsignificantly raised BUA and baseline levels of all bone markers. The ultrasound changes may be accounted for by increase in trabecular separation and a fall in trabecular connectivity due to microfracture. The decrease in bone markers implies a fall in bone turnover. Received: 26 June 1997 / Accepted: 26 August 1998     

海拔3700m富氧室对青年劳动前后血流动力学影响

目的：探讨在高原建立富氧室对青年运动前后血流动力学的影响，为提高高原劳动能力探索有效途径；方法：10名受试者在进入富氧室前后及运动前后分别坐于踏车功量机上，以60rpm连续蹬车，0W为静息时对照值，从25W开始，每3分钟递增25W，蹬车至力竭时停止，然后用XG－Ⅲ血液循环自动测试仪检测血流动力学指标；结果：富氧后运动前P、BK、PAWP、CCP、η、ALT为静息状态均降低，差别有显著性（P＜0．05或P＜0．01），SV、MAP、BV均明显增高，差别有非常显著性（P＜0．001）；富氧后运动后P、BK、TPR较静息状态均升高，差别有显著性（P＜0．05或P＜0．01），PAWP升高明显，差别有非常显著性（P＜0．001），CCP、η、ALT降低明显，差别有非常显著性（P＜0．001），其余指标无统计学意义（P＞0．05）；富氧后运动后SV、CCP、η、mAP、BV、ALT较运动前均降低，差别有显著性（P＜0．05或P＜0．01），P、BK、TPR、PAWP均升高明显，差别有非常显著性（P＜0．001）；结论：高原富氧室可改善劳动者缺氧，增强心功能，提高劳动效率，是一种较理想的高原供氧途径。     

活动平板试验QTc离散度变化对冠心病的诊断意义

目的　研究活动平板运动试验后QTc离散度变化对冠心病诊断的意义。方法　经冠状动脉造影证实为冠心病的患者 32例 ,冠状动脉正常者 2 8例。分析比较两组活动平板运动前和运动后即刻、2min及 4min12导联心电图QTc离散度变化及ST段变化。结果　运动前和运动后即刻、2min及 4min冠心病组QTc离散度分别为 :(4 2± 11)ms;(6 5± 12 )ms ;(6 0± 15 )ms;(4 8± 11)ms。运动后各时间点QTc离散度比运动前明显升高(P <0 0 1) ;冠状动脉正常组运动前、运动后即刻、2min及 4minQTc离散度分别为 (36± 13)ms ;(39± 11)ms;(4 0± 12 )ms ;(38± 14)ms。运动后各时相QTc离散度与运动前比较无明显差异 (P >0 0 5 ) ;运动后冠心病组QTc离散度比正常对照组均明显升高 (P <0 0 1)。以运动后即刻QTc离散度≥ 5 0ms为标准 ,诊断冠心病的敏感性为 84 6 %,特异性为 80 2 %,预测准确性为 87 5 %。高于运动后ST段阳性标准的改变 (P <0 0 5 )。结论运动高峰时QTc离散度增加有助于观察心肌缺血程度 ,可作为诊断冠心病的参考指标。     

An 8-week aerobic cycling intervention elicits improved gait velocity and biomechanics in persons with Parkinson’s disease

BackgroundIt is unknown if improvements in gait velocity following an aerobic cycling intervention are accompanied by improved gait biomechanics in individuals with Parkinson’s disease (PD) or if gait abnormalities are exaggerated in response to increased velocity.Research questionCan an 8-week aerobic cycling intervention elicit improvements in locomotor function in individuals with mild to moderate PD?MethodsA secondary analysis of data from a randomized clinical trial was conducted in individuals with mild to moderate idiopathic PD (N = 28). Participants were randomized to an aerobic cycling intervention (PD_ex, N = 14) consisting of 24 sessions at a targeted aerobic intensity of 60–80% of heart rate reserve or to a no intervention control group (PD_control, N = 14). Change in comfortable walking speed in addition to gait kinematics, kinetics, and spatiotemporal variables using motion capture were obtained at baseline and end of treatment (EOT).ResultsThe PD_ex group made significantly greater improvements in the primary outcome, change in comfortable gait velocity, from 0.86 ± 0.24 m/s at baseline to 1.00 ± 0.23 m/s at EOT compared to the PD_control group who declined from 0.91 ± 0.23 m/s at baseline to 0.80 ± 0.29 at EOT (P = 0.002). Improvements in gait velocity for the PD_ex group were accompanied by improvements in gait kinematics, kinetics, and spatiotemporal parameters, while the PD_control group demonstrated slight worsening in all gait parameters over the 8-week period.SignificanceThe 8-week moderate- to high-intensity cycling intervention elicited significantly greater improvements in gait velocity compared to the PD_control group. Increased gait velocity was accompanied by normalization of gait biomechanics, rather than an exaggeration of existing gait deviations. Aerobic cycling may be a viable treatment approach to improve gait velocity and gait biomechanics in individuals with mild to moderate PD and may mitigate declines in mobility.