Resistive Dynamic

Velocity of muscle movement approaches zero, more force can be generated during concentric or muscle shortening contractions. The opposite relation exists in eccentric or muscle lengthening contractions where more force is generated when velocity of contractions increase (Fig. 3.3). Fig. 3.3. Force-velocity relationships for isometric and two types of isotonic muscle contractions eccentric (lengthening) and concentric (shortening). Fig. 3.3. Force-velocity relationships for isometric and two...

Introduction

The interaction between genetics and environment is a major determinant of health, aging, and exercise performance (Simopoulos, 1997 Skinner et al., 2003). While genes provide a blueprint for a variety of phenotypes, environmental and lifestyle factors can modify specific structural, functional, or behavioral characteristics of an organism (Fig. 9.1). Access to physical activity, in particular, is an important factor that directly influences genes that regulate health and longevity. On the...

Exercise and Antioxidant Signaling

Finkel and Holbrook (2000) elegantly stated that the best strategy to enhance endogenous antioxidant levels may actually be oxidative stress itself, based on the classical physiological concept of hormesis. Hormesis is a Greek word meaning a sublethal dose of toxin can increase the tolerance of the organism to withstand higher doses of toxins. Exercise at high intensity is a form of oxidative stress due to the generation of ROS that exceeds the defense capacity in skeletal muscle (McArdle et...

Sprint Exercise and Oxidative Stress

Sprinting is an example of a predominantly anaerobic exercise where the majority of energy transfer is derived from the phosphagen system with little dependence on oxygen flux. Sprinting shares some characteristics of isometric exercise although there is clearly muscle movement involved in sprinting. Some characteristics shared by both isometric and sprinting exercises include high power output and generation of force, low dependence on oxygen for ATP, persistent action potential across the...

Exercise and Collateral Coronary Circulation

The development of collateral coronary circulation may occur in some animal species in response to prolonged (i.e. months to years) endurance exercise training. However, the cardioprotective benefits of short-term exercise are not attributed to alterations in collateral circulation (Yamashita et al., 1999). Thus, by a process of elimination, it seems likely that the cardioprotection observed in response to short-term exercise is due to myocardial expression of cardioprotective molecules....

Cross Training Sports and Oxidative Stress

Basketball and soccer are examples of sports that depend on muscle contractions across the exercise continuum. In basketball, the power involved in vertical jumps for rebounds and endurance necessary for intermittent running over 45 min can cause oxidative stress via a variety of pathways. Soccer players can run up to 10 miles in a 90 min soccer match. Sprinting, kicking, and lunging require short bursts of power and strength. A study by Szczesniak et al. (1998) compared biomarkers of oxidative...