Health-related physical fitness: Status of body composition, musculoskeletal- and neuromotor fitness, and the e ect of a tailored, telephone and email based exercise intervention on body composition and physical fitness

Abstract

Background: The increasing obesity prevalence rates in addition to the increasing physical inactivity rates present serious public health challenges worldwide. The effect of these trends on aspects of health-related physical fitness is unclear as these trends are most commonly assessed by selfreport or simpler objective measures. Up-to-date research on obesity prevalence rates and musculoskeletal- and neuromotor fitness by various well established and objectively measures is lacking. Additionally, the need interventions aiming at reducing both the prevalence of physical inactivity in addition to the prevalence of obesity has been highlighted. Tailored physical activity interventions delivered in alternative technological modes have proven effective in enhancing physical activity levels in adults, however the effect of such interventions on objetively measured aspects of health-related physical fitness among physically inactive adults is lacking.

Purpose: The overall purpose of this thesis was to investigate the status of various aspects of healthrelated physical fitness and to assess the effect of a six-month tailored telephone- and email based exercise intervention on various aspects of health-related physical fitness.

Methods: The results presented in this thesis are based on two separate studies; a national cross-sectional study of Norwegian adults (20-65 years) (PAPERS I and II) and elderly (65-85 years) (PAPER I) in addition to a randomized controlled trial of a six-month tailored exercise intervention in physically inactive adults (40-55 years) (Papers III and IV).

Main results: The main results from PAPER I revealed that obesity prevalence rates ranging from 12.7% based on BMI measures to 30.9% based on waist circumference. The sensitivity and specificity of the different measuring methods for estimating overweight and obesity, varied from 77.0% to 86.9% and from 60.6% to 82.3%, respectively. The main results from PAPER II were the normative data on musculoskeletal- and neuromotor fitness, displaying clear gender (p<0.001) and age related (p≤0.044) differences. Females displayed significantly higher scores on muscular endurance of the back extensors and on the flexibility tests (p < 0.001), while males displayed significantly higher scores on muscular strength, muscular dynamic endurance and ability to stabilize the upper body, as well as explosive power (p < 0.001). Additionally, younger participants displayed higher test scores on all musculoskeletal- and neuromotor fitness tests, compared to older participants (Females; Beta:−0.06–(−0.92), p ≤ 0.044, Males; Beta:−0.15–(0.91), p ≤ 0.006). Furthermore, waist circumference was inversely related to many aspects of musculoskeletal- and neuromotor fitness (p < 0.001).The main findings from PAPER III and PAPER IV revealed significant improvements in test scores on maximal oxygen consumption (VO2max, ml/kg/min) (ES:0.12, p=0.002), muscular endurance of the back extensors (ES:0.21, p<0.001), flexibility of the hamstrings muscles (ES:0.12, p=0.006) and explosive power (ES:0.09, p=0.022)from baseline to posttest in the intervention group, compared to the control group, when adjusting for baseline test scores. Furthermore, the intervention induced a larger reduction on all body compositional measures in the intervention group compared to the control group (p≤0.043) when controlling for baseline test scores, except for BMI. Additionally, a significantly higher percentage of the participants in the intervention group (64.1%) accomplished a clinically significant reduction in fat percentage by skinfolds compared to participants in the control group (36.2%, p=0.018).

Conclusion: The agreement between various objective measures of obesity was fair to good, however, the variation in obesity prevalence rates between the different assessments methods was striking. Additionally, the status of musculoskeletal- and neuromotor fitness reveal clear gender differences and an inverse relationship between musculoskeletal- and neuromotor fitness and age and waist circumference. The six-month tailored telephone- and email based exercise intervention aiming at increasing cardiorespiratory fitness and musculoskeletal- and neuromotor fitness, in addition to reducing various body compositional measures, revealed promising results. Thus, this type of intervention should be further investigated as to elaborate on whether or not any of the components of the intervention are more effective than others, whether or not further elements should be implemented to enhance the effect size of- and adherence to similar interventions, and to assess the long term follow-up of interventions promoting aspects of health-related physical fitness in physically inactive adults.

Paper I: Kjaer IG, Kolle E, Hansen BH, Anderssen SA, Torstveit MK: Obesity prevalence in Norwegian adults assessed by body mass index, waist circumference and fat mass percentage. Clinical obesity 2015, 5(4):211-218.

Paper II: Kjær IGH, Torstveit MK, Kolle E, Hansen BH, Anderssen SA: Normative values for musculoskeletal- and neuromotor fitness in apparently healthy Norwegian adults and the association with obesity: a cross-sectional study. BMC Sports Science, Medicine and Rehabilitation 2016.

Paper III: Kjaer IG, Anderssen SA, Torstveit MK: A tailored telephone and email based exercise intervention increased physical fitness in physically inactive adults: A RCT. Submitted BMC Public Health, 30.10.17

Paper IV: Kjaer IG, Anderssen SA, Torstveit MK: The effect of a tailored telephone and email based exercise intervention on various measures of body composition in physically inactive adults: a randomized controlled trial. Submitted Preventive Medicine Reports, 04.12.17, manuscript number: PMEDR-17-227