Determining How Age and Physiology Influences the Effect of Exercise Intensity on the Heart Rate During Treadmill Exercise

Determining how age and physiology influences the effect of exercise intensity on the heart rate during treadmill exercise

Introduction

Many factors influence the variability of the heart rate, age being one. There is a negative correlation between maximal oxygen uptake and age. It found that oxygen uptake declines at a rate of 10% each decade, starting in the third decade (Hale, 2004). 50 % of maximal aerobic power is reached at a significantly lower heart rate for an older individual. Evaluating an individuals capacity to perform work, involves measuring resting heart rate then calculating an assumed maximal heart rate (Astrand, Rodahl, Dahl & Stromme, 2003).

Cardiac output at rest is similar between trained and untrained individuals. During low intensity exercise, cardiac output of untrained individuals is usually higher than a trained subject (Foss, Keteyian, 1998). Foss et al. state that females usually have a higher cardiac output whilst exercising at the same VO2. Cardiac output is the product of heart rate and stroke volume (Hale, 2004). Resting cardiac output in adults averages 102ml/min per kg of body weight, though surface area is a more generally used term (Milnor, 1992). Blood pressure during rest and in submaximal exercise is directly related to body size. A larger individual will have a larger stroke volume due to having a larger heart (Wilmore, Costill & Kenney, 2008). Ogowa et al. (1992) found that the effects of age and training on cardiac output, and stroke volume cannot be fully explained by body composition.

Wilmore et al. (2008) state that at the start of exercise heart rate increases in direct proportion to exercise intensity, until near maximal effort takes place whereby the heart rate begins to plateau. They also state that resting heart rate should only be measured during total relaxation, so that an accurate HRmax can be achieved. The purpose of this investigation was to study the effect of exercise intensity on a moderately...