The main purpose of this study was to compare the acute effects of static and dynamic stretching in the warm-up, on hamstring flexibility using a reliable set-up for measurement. Static and dynamic flexibility was measured using five modifications of the Straight Leg Raise (SLR) test to measure hip flexion range of motion (ROM). In the first part of the study (n = 33) hamstring flexibility was measured using a Static-passive, Static-active, Dynamic-supine and Dynamic-standing tests. The results of this study were used to calculate reliability statistics and to compare the various static and dynamic flexibility tests. There was a significant difference between Static-passive (SPH) and the Dynamic-supine (DSUH) tests (p less than .05). This was followed by an intervention study (n = 12) where participants were randomly assigned to three intervention treatments of 225 seconds on separate days: No stretching (Treatment I), Static stretching (Treatment 2) and Dynamic stretching (Treatment 3) in a cross-over study design. Static stretching had no impact on dynamic hamstring flexibility; however, dynamic stretching improved dynamic flexibility while simultaneously increasing static flexibility. This has implications for the specificity of stretching in sport.

<p>Flexible queuing systems arise III a variety of applications, such as service operations, computer/communication systems and manufacturing. In such a system, customer types vary in the flexibility of choosing servers; servers vary in the flexibility of which types of customers to serve. This thesis studies several resource allocation policies which address the concerns of limited customer choice and server flexibility. First, to accommodate different levels of flexibility, we propose the MinDrift affinity routing (MARa) policy and three variants: MARO-2/k, MARO-flex and MARa-tree. These policies are designed to maximize the system capacity by using the first moments of the interarrival times and the service times, at the same time they require only a small amount of state information in minimizing the delay in the system. Using diffusion limits for systems with Poisson arrival processes, we prove that MARa, MARO-flex and MARO-tree have the same heavy traffic optimality properties and the optimality is achieved independent of the flexibility levels. By providing their applications in distributed computing systems, we show that the MARa related policies (which require significantly less state information) outperform the MinDrift(Q) policy (which requires global state information), in heterogeneous server systems with either high or medium loads. Second, when no state information is available, we propose both the random routing policy which asymptotically minimizes the delay in the system by using the second moments of the service times, and the pooling strategy which further reduces the delay by combining appropriate parallel single-server queues into a number of multi-server queues. Overall, this thesis intends to provide insights on designing effective policies for allocating servers' times to serve multiple types of customers.</p> / Doctor of Philosophy (PhD)