Research

Work Ability, Physical Activity, and Cardiorespiratory Fitness: 2-year Results From Project Active

An adequate level of physical activity may maintain or promote work ability in aging workers. Project Active is a randomized trial comparing a Lifestyle physical activity program with a Structured exercise program in sedentary but healthy adults aged 35 to 60 years. Subjects in both groups received 6 months of intensive intervention followed by 18 months of active follow-up. The total number of subjects was 235, from which 80 subjects participated in the work ability assessment. Primary outcome measures were energy expenditure (kcal · kg⁻¹ · day⁻¹), cardiorespiratory fitness (peak oxygen uptake in ml · min⁻¹ · kg⁻¹), and the Work Ability Index. At 6 months, daily energy expenditure had increased significantly over baseline (mean ± SD, from 33.0 ± 0.9 to 34.4 ± 1.8 kcal · kg⁻¹ · day⁻¹) and was maintained over baseline at 24 months (34.0 ± 2.5 kcal · kg⁻¹ · day⁻¹). The significant increase in energy expenditure was observed particularly in moderate levels of activity. The average percentage of body fat was significantly higher at baseline compared with 6 months and 24 months. Peak oxygen uptake increased from baseline significantly during the first 6 months (from 29.6 ± 5.7 to 30.6 ± 6.3 ml · min⁻¹ · kg⁻¹) and decreased to the baseline level (29.1 ± 5.5 ml · min⁻¹ · kg⁻¹) at 24 months. At baseline, the average Work Ability Index was 44.2 ± 4.0, and it remained unchanged at 6 months (44.4 ± 3.9) and at 24 months (44.2 ± 3.1). In conclusion, a 2-year physical activity intervention increased daily energy expenditure, reduced body fat, and maintained peak oxygen uptake in healthy, middle-aged, sedentary subjects. The average Work Ability Index score at baseline was excellent and did not change during the 2-year physical activity interventions.

- http://journals.lww.com/joem/Abstract/2000/09000/Work_Ability,_Physical_Activity,_and.12.aspx

This page describes and explains the way that changing the concentration of a solution affects the rate of a reaction. Be aware that this is an introductory page only.

Introduction

For many reactions involving liquids or gases, increasing the concentration of the reactants increases the rate of reaction. In a few cases, increasing the concentration of one of the reactants may have little noticeable effect of the rate. These cases are discussed and explained further down this page. Don't assume that if you double the concentration of one of the reactants that you will double the rate of the reaction. It may happen like that, but the relationship may well be more complicated.

 

 

http://chemwiki.ucdavis.edu/Physical_Chemistry/Kinetics/Rate_Laws/Reaction_Mechanisms/Reaction_Mechanisms/The_Effect_of_Concentration_on_Rate_of_Reaction#Contributors