Physical activity, body composition, inflammation and effects on antioxidative capacity in sedentary adults

Abstract

Background: For the past fifty years part the population has slowly become sedentary to an extent that it is nowadays considered normal behavior. Parallel with sedentary behavior there is an increase in obesity now reaching epidemic level. Metabolic derangements such as diabetes type 2 and cardiovascular diseases has become an economic burden for the modern society. Implementation of training programs for individuals that have been sedentary for years has often been demonstrated inefficient, with few and short-lasting effects.

Aim: The primary aim of this thesis was to study effects of increased physical activity at different intensities in distinct sedentary populations. The secondary aim was to investigate if there was a gender difference in adaption to short-term endurance training.

Methodology: Study I: Two hundred and twelve (age 45-69 years) sedentary overweight men and women were included. They were classified as normal or impaired glucose tolerance, or diabetes type 2. They were randomized into controls or intervention group. The intervention group was instructed to increase their physical activity by walking with poles (Nordic walking) 5 h per week. Questionnaire, blood samples, anthropometric data and results from an exercise test were collected at baseline and after 4 months.

Study II: Fourteen healthy (22-30 year-old) sedentary normal weight women and men participated in a 3 weeks endurance training program including 2 supervised sessions per day. The training period was followed by 4 weeks of detraining. Blood samples including total antioxidative capacity (TAOC) and oxidative stress (OS), body composition (BC), anthropometric data and evaluation of work capacity were obtained at baseline, after training and after detraining.

Result: Study I: Nordic walking improved waist circumference, body weight and body mass index in the intervention group with normal glucose tolerance. Participants that reported > 80 % adherence to training improved work capacity in terms of work load, VO2 peak, or both, in all groups. Biochemical markers were unaffected.

Study II: TAOC levels decreased significantly in women after training, while no change was noted in men. After training both gender showed increased work load, VO2 peak even adjusted for fat-free mass, and ventilation. After detraining, work load and VO2 peak decreased in women. Adjusted VO2 peak decreased also in men but remained higher compared to baseline. Fat-free mass (kg) was higher after detraining compared to baseline in women. Conclusion: Study I: Nordic walking had positive anthropometric effects among those with normal glucose tolerance. It could be applied in clinical practice, but surveillance of training might be necessary to reach optimal results among sedentary individuals.

Study II: Female participants were more sedentary and their exercise capacity improved to a greater degree. Their decrease in TAOC might reflect an increased consumption of antioxidants to prevent negative effects of OS. A higher level of daily regular physical activity in men could explain their maintenance of improved VO2peak after detraining.