The Effect of Structured Exercise Intervention on Intensity and Volume of Total Physical Activity

This study aimed to investigate the effects of a 12-week structured exercise intervention on total physical activity and its subcategories. Twenty-three overweight or obese middle aged men with impaired glucose regulation were randomized into a 12-week Nordic walking group, a power-type resistance training group, and a non-exercise control group. Physical activity was measured with questionnaires before the intervention (1–4 weeks) and during the intervention (1–12 weeks) and was expressed in metabolic equivalents of task. No significant change in the volume of total physical activity between or within the groups was observed (p > 0.050). The volume of total leisure-time physical activity (structured exercises + non-structured leisure-time physical activity) increased significantly in the Nordic walking group (p 0.050) compared to the control group. In both exercise groups increase in the weekly volume of total leisure-time physical activity was inversely associated with the volume of non-leisure-time physical activities. In conclusion, structured exercise intervention did not increase the volume of total physical activity. Albeit, endurance training can increase the volume of high intensity physical activities, however it is associated with compensatory decrease in lower intensity physical activities. To achieve effective personalized exercise program, individuality in compensatory behavior should be recognised. Key Points Structured NW or RT training does not increase the volume of total physical activity. NW intervention can increase the volume of higher intensity activities. The increased in volume of LTPA induced by the structured NW and RT interventions was associated with the decreased volume of NLTPA. Key words: Nordic walking, resistance training, energy expenditure, thermogenesis, glucose intolerance Introduction Physical inactivity is the fourth largest risk factor for mortality and a major risk factor for non-communicable diseases (World Health Organization, 2009). The worldwide prevalence of non-communicable diseases, including diabetes, cardiovascular disease, and cancer, is increasing and they are estimated to account for 63% of global deaths (World Health Organization, 2011). Combined evidence from 76 countries suggests that approximately 25% (range 2.6% – 62.3%) of people are currently sedentary (Dumith et al., 2011). Thus, one of the leading targets in the prevention of non-communicable diseases is to enhance the overall intensity and volume of physical activity. The prevention of physical inactivity and related diseases pertains all professionals working in health care, especially exercise physiologists and physiotherapists who have expertise in exercise prescription. Physical exercises are often prescribed as a first line of defence against inactivity. Such interventions, however may result in compensatory decrease in non-exercise physical activity (King et al., 2007). Non-exercise physical activity has been shown to decrease with cycling (Goran and Poehlman, 1992, Morio et al., 1998, Manthou et al., 2010), walking (Colley et al., 2010), or combined resistance and aerobic training (Meijer et al., 1999) exercise interventions. However, the current evidence regarding the compensatory response is inconsistent (Hollowell et al., 2009, Turner et al., 2010). In previous studies physical activity measurements have accounted only for a small portion of the intervention and focusing mainly on the change in total energy expenditure. Thus, the effect of exercise on non-exercise physical activity during the whole intervention remains to be determined, especially in the sense of intensity and volume. Better understanding of compensatory behavior, could enable more personalized and effective dosage of exercise for different impairments and medical conditions. The purpose of this study was to measure total physical activity during an exercise intervention and to investigate the effects of a 12-week structured aerobic training (Nordic walking) and power-type resistance training on the intensity and volume of total physical activity and its subcategories. An additional aim was to define the correlates for changes in physical activity.