The effects of isometric exercise training on resting blood pressure with specific reference to selected cardiovascular, neuromuscular, and metabolic variables

There were two purposes to the work of this thesis (a) to identify the role of isometric training intensity in the training-induced reductions in resting blood pressure, and (b) to identify whether the mechanism for the reduced resting blood pressure is best reflected in what can be broadly termed cardiovascular, neuromuscular or metabolic markers of that training. Firstly, in a cross-sectional study, the only strong correlation was found between heart rate variability (a cardiovascular marker) and resting blood pressure. Secondly, this cardiovascular marker was also significantly affected by a single session of isometric exercise, an effect that persisted for at least 4 hours after exercise. However, thirdly, this marker and other cardiovascular markers (such as cardiac output and stroke volume) did not correlate with reductions in blood pressure seen after 4 weeks of isometric training. Instead, the training-induced reductions in blood pressure correlated strongly with neuromuscular and metabolic markers of isometric training. The extent to which local muscle fatigue was induced during isometric training correlated with the reductions in resting blood pressure. Therefore (a) isometric training intensity appears to be of utmost importance in the reductions in resting blood pressure (when bilateral-leg exercise is performed in 2 minute bouts), and (b) the mechanism whereby the adaptations in resting blood pressure occur is best reflected in neuromuscular and metabolic markers of local muscle fatigue during that training. These findings are discussed with a particular focus on the possible role of muscle metaboreceptor stimulation, during isometric training in the mechanism of training-induced reduction in resting blood pressure

The Extent and Consequences of Downward Nominal Wage Rigidity

Using the Panel Study of Income Dynamics, we find that true wage changes have many fewer nominal cuts and more nominal freezes than reported nominal wage changes. The data overwhelmingly rejects a model of flexible wage changes and provides some evidence against a model of perfect downward rigidity in favor of a more general model. The more general model incorporates downward rigidity but specifies that nominal wage cuts may occur when large cuts would occur in the absence of wage rigidity. However, the results of the general model imply that nominal wage cuts are rare. We also analyze the personnel files of a large corporation and find cuts in base pay are rare and almost always associated with changes in full time status or a switch between compensation schemes involving incentives. Our evidence on the consequences of nominal wage rigidity is mixed. We find modest support for the hypothesis that workers who are overpaid because of nominal wage rigidity are less likely to quit.

The More the Merrier? The Effect of Family Composition on Children's Education

Among the perceived inputs in the production' of child quality is family size; there is an extensive theoretical literature that postulates a tradeoff between child quantity and quality within a family. However, there is little causal evidence that speaks to this theory. Our analysis is able to overcome many limitations of the previous literature by using a rich dataset that contains information on the entire population of Norway over an extended period of time and allows us to match adult children to their parents and siblings. In addition, we use exogenous variation in family size induced by the birth of twins to isolate causation. Like most previous studies, we find a negative correlation between family size and children's educational attainment. However, when we include indicators for birth order, the effect of family size becomes negligible. This finding is robust to the use of twin births as an instrument for family size. In addition, we find that birth order has a significant and large effect on children's education; children born later in the family obtain less education. These findings suggest the need to revisit economic models of fertility and child production', focusing not only on differences across families but differences within families as well.

From the Cradle to the Labor Market? The Effect of Birth Weight on Adult Outcomes

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Under Pressure? The Effect of Peers on Outcomes of Young Adults

A variety of public campaigns, including the "Just Say No" campaign of the 1980s and 1990s that encouraged teenagers to "Just Say No to Drugs", are based on the premise that teenagers are very susceptible to peer influences. Despite this, very little is known about the effect of school peers on the long-run outcomes of teenagers. This is primarily due to two factors: the absence of information on peers merged with long-run outcomes of individuals and, equally important, the difficulty of separately identifying the role of peers. This paper uses data on the population of Norway and idiosyncratic variation in cohort composition within schools to examine the role of peer composition in 9th grade on longer-run outcomes such as IQ scores at age 18, teenage childbearing, post-compulsory schooling educational track, adult labor market status, and earnings. We find that outcomes are influenced by the proportion of females in the grade, and these effects differ for men and women. Other peer variables (average age, average mother's education) have little impact on the outcomes of teenagers.education, peer effects

Too Young to Leave the Nest? The Effects of School Starting Age

Does it matter when a child starts school? While the popular press seems to suggest it does, there is limited evidence of a long-run effect of school starting age on student outcomes. This paper uses data on the population of Norway to examine the role of school starting age on longer-run outcomes such as IQ scores at age 18, educational attainment, teenage pregnancy, and earnings. Unlike much of the recent literature, we are able to separate school starting age from test age effects using scores from IQ tests taken outside of school, at the time of military enrolment, and measured when students are around age 18. Importantly, there is variation in the mapping between year and month of birth and the year the test is taken, allowing us to distinguish the effects of school starting age from pure age effects. We find evidence for a small positive effect of starting school younger on IQ scores measured at age 18. In contrast, we find evidence of much larger positive effects of age at test, and these results are very robust. We also find that starting school younger has a significant positive effect on the probability of teenage pregnancy, but has little effect on educational attainment of boys or girls. There appears to be a short-run positive effect on earnings of beginning school at a younger age; however, this effect has essentially disappeared by age 30. This pattern is consistent with the idea that starting school later reduces potential labor market experience at a given age for a given level of education; however, this becomes less important as individuals age.education, earnings, IQ, teenage childbearing

Like Father, Like Son? A Note on the Intergenerational Transmission of IQ Scores

More able parents tend to have more able children. While few would question the validity of this statement, there is little large-scale evidence on the intergenerational transmission of IQ scores. Using a larger and more comprehensive dataset than previous work, we are able to estimate the intergenerational correlation in IQ scores, examining not just average correlations but also how this relationship varies for different subpopulations. We find that there is substantial intergenerational transmission of IQ scores; an increase in father’s IQ at age 18 of 10% is associated with a 3.2% increase in son’s IQ at the same age. This relationship holds true no matter how we break the data. This effect is much larger than our estimated elasticity of intergenerational transmission of income of approximately .2.ability, intergenerational mobility

Older and Wiser? Birth Order and IQ of Young Men

While recent research finds strong evidence that birth order affects children's outcomes such as education and earnings, the evidence on the effects of birth order on IQ is decidedly mixed. This paper uses a large dataset on the population of Norway that allows us to precisely measure birth order effects on IQ using both cross-sectional and within-family methods. Importantly, irrespective of method, we find a strong and significant effect of birth order on IQ, and our results suggest that earlier born children have higher IQs. Our preferred estimates suggest differences between first-borns and second-borns of about one fifth of a standard deviation or approximately 3 IQ points. Despite these large average effects, birth order only explains about 3% of the within-family variance of IQ. When we control for birth endowments, the estimated birth order effects increase. Thus, our analysis suggests that birth order effects are not biologically determined. Also, there is no evidence that birth order effects occur because later-born children are more affected by family breakdown.

Under Pressure? The Effect of Peers on Outcomes of Young Adults

A variety of public campaigns, including the “Just Say No” campaign of the 1980s and 1990s that encouraged teenagers to “Just Say No to Drugs”, are based on the premise that teenagers are very susceptible to peer influences. Despite this, very little is known about the effect of school peers on the long-run outcomes of teenagers. This is primarily due to two factors: the absence of information on peers merged with long-run outcomes of individuals and, equally important, the difficulty of separately identifying the role of peers. This paper uses data on the population of Norway and idiosyncratic variation in cohort composition within schools to examine the role of peer composition in 9th grade on longer-run outcomes such as IQ scores at age 18, teenage childbearing, postcompulsory schooling educational track, adult labor market status, and earnings. We find that outcomes are influenced by the proportion of females in the grade, and these effects differ for men and women. Other peer variables (average age, average mother’s education) have little impact on the outcomes of teenagers.