Upper-body exercise elicits a different cardiovascular response than lower-body exercise. This is most in part due to more muscle activation involved in the larger muscle groups of the legs compared to the smaller arm muscles. More oxygen can be utilized by the legs due to their larger muscularity, which is why VO2 values are higher in lower body exercise. Peak O2 uptake in upper-body exercise can be 20-30% lower than values produced in lower-body exercise. (more…)
Hemoglobin plays a crucial role in the transportation of oxygen. The pressure of oxygen in blood determines how much O2 is bound to hemoglobin. The oxyhemoglobin dissociation curve represents the percentage of O2 saturation of hemoglobin at varying oxygen pressures. At sea level, resting O2 saturation is 98% and is represented by the upper/right-most point on the curve (Fig. 1). As exercise intensity increases and more O2 is being used by muscle tissue, PO2 decreases as a result. (more…)
Adaptations to heat stress from exercising in hot environments can occur. The thermoregulatory system can adapt to allow for more efficient and effective heat removal. This adaptation is referred to as heat acclimatization. With heat acclimatization, sweating starts earlier and the amount of sweat produced during exercise in heat is increased to allow for more cooling due to evaporation.5 As a result, skin temperature will be cooler and less blood flow will be directed to the skin and a higher volume will be available for the exercising muscle.5 (more…)
In a hot, but windy environment convection will play a larger role in facilitating heat removal from the body compared to an non-windy inland environment. The circulating air will be constantly replacing the warm air around the body referred to as the zone of insulation.1 This prevents heat gain due to convection. In hot, dry conditions evaporation can take place relatively uninterrupted due to the low percentage of moisture in the air. (more…)
The human body has a thermoregulatory system that tries to maintain a core body temperature of 37 degrees Celsius under varying conditions.1 However, heat loss due to cold environments, for example, or heat gain as a result of exercise and hot environments will put considerable strain on this regulatory system. During exercise, the heat formed from energy metabolism in working muscle is transported to the skin so it can leave the body to be dissipated into the environment. (more…)
