High-intensity interval training to counteract the age-related loss of muscle mass in middle-aged adults.

INTERVENTION: The intervention includes a 40‐week randomized controlled trial of high intensity aerobic and resistance interval training (HIART). The 40‐week intervention involves 20 weeks of training followed by a 20‐week follow‐up. Each training session will start with a warming up, then the HIART training and ends with a cool‐down. The HIART training involves three phases, set up as a circuit. The three phases are; 1) a “powerâ€? phase, consisting of three whole‐body resistance exercises (e.g. jumping jacks, lunges, push‐ups, squats) 2) 10 minutes of high‐intensity cardiorespiratory cycling 3) 3 sets of 3 free weight exercises, with appropriate rest between each phase (e.g. biceps curl, weighted lunges, weighted squats). Training load will be self‐selected from designated options but participants will be encouraged to choose a wattage that will ensure that their heart rate reaches 85% of their maximum heart rate during the high‐intensity peaks and does not drop below 60% of their maximum heart rate during the low‐intensity periods. All training sessions are group‐based, with a maximum of 10 people in each group. All training sessions will be provided by a trained and experienced physiotherapist. In order to maximize adherence, participants will receive an appointment card every first session of the week and they will receive a text message 24 hours before the exercise session. Adherence will be monitored using attendance checklists by the physiotherapist. CONDITION: Musculoskeletal ‐ Other muscular and skeletal disorders Physical Medicine / Rehabilitation ‐ Other physical medicine / rehabilitation Pro‐dromal sarcopenia;Pro‐dromal sarcopenic‐obesity; ; Pro‐dromal sarcopenia ; Pro‐dromal sarcopenic‐obesity PRIMARY OUTCOME: Muscle mass will be assessed with Dual‐energy X‐ray absorptiometry (DXA) and analysed using DXA software (Lunar Prodigy, GE Medical Systems, Madison, WI). [Baseline (1 week before start intervention) ; Post‐intervention (20 weeks post‐intervention commencement); Long‐term follow‐up (40 weeks post‐intervention commencement)] SECONDARY OUTCOME: A 3RM‐test will be performed to measure strength of the upper extremities with a biceps curl. ; [Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] A 3RM‐test will be performed to measure the strength of the lower extremities, with a leg press. ; [Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] Aerobic endurance will be measured using a VO2max cycle test.[Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] Gait speed will be measured with the four‐meter gait speed test.[Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] Grip strength will be measured using the JAMAR Handheld Dynamometer.[Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] Isokinetic strength of the knee‐extensor (m. quadriceps) will be measured using Biodex (Biodex Corporation, Shirley, NY, USA). [Baseline (1 week before start intervention) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] Isometric strength of the knee‐extensor (m. quadriceps) will be measured using Biodex (Biodex Corporation, Shirley, NY, USA). [Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] Lower extremity strength and endurance will be measured with the 30 Seconds Sit to Stand Test.[Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] Physical activity (steps/day) will be measured by using an accelerometer attached to a waist strap (Actigraph GT3X+, Pensacola, FL, USA). [Baseline (1 week before start intervention) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] To measure health status, Short Form 12 Health Survey (SF‐12) will be completed. [Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] To measure the perceived enjoyment of physical activity, the 18‐item Physical Activity Enjoyment Scale (PACES) will be completed.[Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] To measure the self‐efficacy of physical activity, the 18‐item Exercise Self‐Efficacy scale (ESES) will be completed.[Baseline (1 week before start intervention) ; Interim‐intervention (10 weeks after intervention commencement) ; Post‐intervention (20 weeks post‐intervention commencement) ; Long‐term follow‐up (40 weeks post‐intervention commencement)] INCLUSION CRITERIA: Inclusion criteria will include otherwise healthy men and women aged between 40 and 50 years of age, who are not meeting the physical activity guidelines (2.5 hours a week of moderate activity) and are at risk of developing low muscle mass. Being at risk of developing low muscle mass will be assessed using a newly developed screening tool.