PHYSIOLOGICAL RESPONSE TO EXERCISE WITH WEIGHT GAIN AND WEIGHT LOSS. A report.

Introduction

This report examines the extent to which the weight gain and weight loss alter the physiological response to exercise. The body requires an adequate amount of energy for muscle contractions and relaxations, metabolic reactions, and to run other physiological systems of the body according to the demand of the type and nature of the exercise. For the energy production in the body by any physiological pathways aerobically, adequate consumption of oxygen is mandatory.

Energy expenditure during walking or running mainly depends on force require to support body weight, work done to redirect and accelerate the vertical displacement of body’s center of mass, swinging of the limbs and muscle work to maintain stability. Farley & Mcmahon, 1992 and Kram & Taylor, 1950 studies’ suggest that the energy expended to support the body weight is the prime factor of the running economy (RE). RE is the measure of a person’s oxygen consumption while running at a given velocity and is expressed as the rate of oxygen consumption per distance covered (Saunders, 2004). Montoye, Kemper, Saris & Washburn (1996, p. 4) states that “if exercise is to be expressed as energy expenditure in joules or calories, body size must be taken into account”.

Abstract

This report aims to: a) measure changes in energy expenditure with weight gain or weight loss during walking and running; b) observe if these changes are more apparent when walking/ running uphill; c) measure heart rate response to exercise with weight gain and weight loss.

“The energy expended during weight bearing exercise increases directly with the body mass transported”, Mc. Ardle et. al., (2000, p. 162). We hypothesized that body consumes more energy or uses more amount of oxygen when exercising with weighting. Thus, a fat person with greater body mass uses more oxygen while doing weight-bearing exercises like walking and running in comparison to a thin person or with de-weighting. Running involves a repetitive number of single leg stance and due to a reduced base of support, lesser limb mechanical advantage, the lower limb muscles especially knee extensors undergoing strong eccentric contractions and also concentric contractions of hamstrings, resulting in the demand for more energy.

We investigated the metabolic cost of running and walking with weighted and de-weighted in a normal and 10% gradient treadmill test on the basis of measurement of whole body oxygen consumption (VO₂) and respiratory exchange ratio (RER).

Results

Overall, we found that oxygen consumption reflecting the energy expense increased in slightly less than direct proportion to the added weight and decreased in more than the reduced body weight (Table 1). We also found that energy cost is markedly higher for both walking and running in all normal, weighted and de-weighted conditions in an uphill than in a flat horizontal condition (Table 1).

Conclusion

We found that body weight causes the difference in the energy cost level in weight-bearing exercises like walking and running. A person with greater body weight uses a greater amount of oxygen than a thin person to do the same intensity level exercises. It takes more energy to propel body weight forward in the inclined path than to propel on a horizontal plane pathway. We found that running requires more energy consumption than walking in any weight conditions. However, calculating the energy requirements only on the basis of oxygen consumption is not an accurate way. A lot of other factors also play a marked role in energy expenditures during exercises.